btrfs-progs: check: introduce function to check dir_item
[platform/upstream/btrfs-progs.git] / btrfs-convert.c
index e79f670..4b4cea4 100644 (file)
 #include "utils.h"
 #include "task-utils.h"
 
+#if BTRFSCONVERT_EXT2
 #include <ext2fs/ext2_fs.h>
 #include <ext2fs/ext2fs.h>
 #include <ext2fs/ext2_ext_attr.h>
 
 #define INO_OFFSET (BTRFS_FIRST_FREE_OBJECTID - EXT2_ROOT_INO)
-#define CONV_IMAGE_SUBVOL_OBJECTID BTRFS_FIRST_FREE_OBJECTID
 
 /*
  * Compatibility code for e2fsprogs 1.41 which doesn't support RO compat flag
 #define EXT2FS_B2C(fs, blk)            (blk)
 #endif
 
+#endif
+
+#define CONV_IMAGE_SUBVOL_OBJECTID BTRFS_FIRST_FREE_OBJECTID
+
 struct task_ctx {
        uint32_t max_copy_inodes;
        uint32_t cur_copy_inodes;
@@ -99,6 +103,7 @@ struct btrfs_convert_operations {
                         struct btrfs_root *root, int datacsum,
                         int packing, int noxattr, struct task_ctx *p);
        void (*close_fs)(struct btrfs_convert_context *cctx);
+       int (*check_state)(struct btrfs_convert_context *cctx);
 };
 
 static void init_convert_context(struct btrfs_convert_context *cctx)
@@ -128,6 +133,11 @@ static inline void convert_close_fs(struct btrfs_convert_context *cctx)
        cctx->convert_ops->close_fs(cctx);
 }
 
+static inline int convert_check_state(struct btrfs_convert_context *cctx)
+{
+       return cctx->convert_ops->check_state(cctx);
+}
+
 static int intersect_with_sb(u64 bytenr, u64 num_bytes)
 {
        int i;
@@ -273,7 +283,7 @@ static int record_file_blocks(struct blk_iterate_data *data,
        int ret = 0;
        struct btrfs_root *root = data->root;
        struct btrfs_root *convert_root = data->convert_root;
-       struct btrfs_path *path;
+       struct btrfs_path path;
        u64 file_pos = file_block * root->sectorsize;
        u64 old_disk_bytenr = disk_block * root->sectorsize;
        u64 num_bytes = num_blocks * root->sectorsize;
@@ -285,9 +295,7 @@ static int record_file_blocks(struct blk_iterate_data *data,
                                data->objectid, data->inode, file_pos, 0,
                                num_bytes);
 
-       path = btrfs_alloc_path();
-       if (!path)
-               return -ENOMEM;
+       btrfs_init_path(&path);
 
        /*
         * Search real disk bytenr from convert root
@@ -306,11 +314,11 @@ static int record_file_blocks(struct blk_iterate_data *data,
                key.type = BTRFS_EXTENT_DATA_KEY;
                key.offset = cur_off;
 
-               ret = btrfs_search_slot(NULL, convert_root, &key, path, 0, 0);
+               ret = btrfs_search_slot(NULL, convert_root, &key, &path, 0, 0);
                if (ret < 0)
                        break;
                if (ret > 0) {
-                       ret = btrfs_previous_item(convert_root, path,
+                       ret = btrfs_previous_item(convert_root, &path,
                                                  data->convert_ino,
                                                  BTRFS_EXTENT_DATA_KEY);
                        if (ret < 0)
@@ -320,8 +328,8 @@ static int record_file_blocks(struct blk_iterate_data *data,
                                break;
                        }
                }
-               node = path->nodes[0];
-               slot = path->slots[0];
+               node = path.nodes[0];
+               slot = path.slots[0];
                btrfs_item_key_to_cpu(node, &key, slot);
                BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY ||
                       key.objectid != data->convert_ino ||
@@ -330,7 +338,7 @@ static int record_file_blocks(struct blk_iterate_data *data,
                extent_disk_bytenr = btrfs_file_extent_disk_bytenr(node, fi);
                extent_num_bytes = btrfs_file_extent_disk_num_bytes(node, fi);
                BUG_ON(cur_off - key.offset >= extent_num_bytes);
-               btrfs_release_path(path);
+               btrfs_release_path(&path);
 
                if (extent_disk_bytenr)
                        real_disk_bytenr = cur_off - key.offset +
@@ -353,7 +361,7 @@ static int record_file_blocks(struct blk_iterate_data *data,
                 * need to waste CPU cycles now.
                 */
        }
-       btrfs_free_path(path);
+       btrfs_release_path(&path);
        return ret;
 }
 
@@ -420,8 +428,16 @@ static int create_image_file_range(struct btrfs_trans_handle *trans,
        int i;
        int ret;
 
-       BUG_ON(bytenr != round_down(bytenr, root->sectorsize));
-       BUG_ON(len != round_down(len, root->sectorsize));
+       if (bytenr != round_down(bytenr, root->sectorsize)) {
+               error("bytenr not sectorsize aligned: %llu",
+                               (unsigned long long)bytenr);
+               return -EINVAL;
+       }
+       if (len != round_down(len, root->sectorsize)) {
+               error("length not sectorsize aligned: %llu",
+                               (unsigned long long)len);
+               return -EINVAL;
+       }
        len = min_t(u64, len, BTRFS_MAX_EXTENT_SIZE);
 
        /*
@@ -510,7 +526,11 @@ static int create_image_file_range(struct btrfs_trans_handle *trans,
                            bg_cache->key.offset - bytenr);
        }
 
-       BUG_ON(len != round_down(len, root->sectorsize));
+       if (len != round_down(len, root->sectorsize)) {
+               error("remaining length not sectorsize aligned: %llu",
+                               (unsigned long long)len);
+               return -EINVAL;
+       }
        ret = btrfs_record_file_extent(trans, root, ino, inode, bytenr,
                                       disk_bytenr, len);
        if (ret < 0)
@@ -523,1765 +543,1835 @@ static int create_image_file_range(struct btrfs_trans_handle *trans,
 }
 
 /*
- * Open Ext2fs in readonly mode, read block allocation bitmap and
- * inode bitmap into memory.
+ * Relocate old fs data in one reserved ranges
+ *
+ * Since all old fs data in reserved range is not covered by any chunk nor
+ * data extent, we don't need to handle any reference but add new
+ * extent/reference, which makes codes more clear
  */
-static int ext2_open_fs(struct btrfs_convert_context *cctx, const char *name)
+static int migrate_one_reserved_range(struct btrfs_trans_handle *trans,
+                                     struct btrfs_root *root,
+                                     struct cache_tree *used,
+                                     struct btrfs_inode_item *inode, int fd,
+                                     u64 ino, u64 start, u64 len, int datacsum)
 {
-       errcode_t ret;
-       ext2_filsys ext2_fs;
-       ext2_ino_t ino;
-       u32 ro_feature;
+       u64 cur_off = start;
+       u64 cur_len = len;
+       u64 hole_start = start;
+       u64 hole_len;
+       struct cache_extent *cache;
+       struct btrfs_key key;
+       struct extent_buffer *eb;
+       int ret = 0;
 
-       ret = ext2fs_open(name, 0, 0, 0, unix_io_manager, &ext2_fs);
-       if (ret) {
-               fprintf(stderr, "ext2fs_open: %s\n", error_message(ret));
-               return -1;
-       }
-       /*
-        * We need to know exactly the used space, some RO compat flags like
-        * BIGALLOC will affect how used space is present.
-        * So we need manuall check any unsupported RO compat flags
-        */
-       ro_feature = ext2_fs->super->s_feature_ro_compat;
-       if (ro_feature & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP) {
-               error(
-"unsupported RO features detected: %x, abort convert to avoid possible corruption",
-                     ro_feature & ~EXT2_LIB_FEATURE_COMPAT_SUPP);
-               goto fail;
-       }
-       ret = ext2fs_read_inode_bitmap(ext2_fs);
-       if (ret) {
-               fprintf(stderr, "ext2fs_read_inode_bitmap: %s\n",
-                       error_message(ret));
-               goto fail;
-       }
-       ret = ext2fs_read_block_bitmap(ext2_fs);
-       if (ret) {
-               fprintf(stderr, "ext2fs_read_block_bitmap: %s\n",
-                       error_message(ret));
-               goto fail;
-       }
-       /*
-        * search each block group for a free inode. this set up
-        * uninit block/inode bitmaps appropriately.
-        */
-       ino = 1;
-       while (ino <= ext2_fs->super->s_inodes_count) {
-               ext2_ino_t foo;
-               ext2fs_new_inode(ext2_fs, ino, 0, NULL, &foo);
-               ino += EXT2_INODES_PER_GROUP(ext2_fs->super);
-       }
+       while (cur_off < start + len) {
+               cache = lookup_cache_extent(used, cur_off, cur_len);
+               if (!cache)
+                       break;
+               cur_off = max(cache->start, cur_off);
+               cur_len = min(cache->start + cache->size, start + len) -
+                         cur_off;
+               BUG_ON(cur_len < root->sectorsize);
 
-       if (!(ext2_fs->super->s_feature_incompat &
-             EXT2_FEATURE_INCOMPAT_FILETYPE)) {
-               fprintf(stderr, "filetype feature is missing\n");
-               goto fail;
-       }
+               /* reserve extent for the data */
+               ret = btrfs_reserve_extent(trans, root, cur_len, 0, 0, (u64)-1,
+                                          &key, 1);
+               if (ret < 0)
+                       break;
 
-       cctx->fs_data = ext2_fs;
-       cctx->blocksize = ext2_fs->blocksize;
-       cctx->block_count = ext2_fs->super->s_blocks_count;
-       cctx->total_bytes = ext2_fs->blocksize * ext2_fs->super->s_blocks_count;
-       cctx->volume_name = strndup(ext2_fs->super->s_volume_name, 16);
-       cctx->first_data_block = ext2_fs->super->s_first_data_block;
-       cctx->inodes_count = ext2_fs->super->s_inodes_count;
-       cctx->free_inodes_count = ext2_fs->super->s_free_inodes_count;
-       return 0;
-fail:
-       ext2fs_close(ext2_fs);
-       return -1;
-}
+               eb = malloc(sizeof(*eb) + cur_len);
+               if (!eb) {
+                       ret = -ENOMEM;
+                       break;
+               }
 
-static int __ext2_add_one_block(ext2_filsys fs, char *bitmap,
-                               unsigned long group_nr, struct cache_tree *used)
-{
-       unsigned long offset;
-       unsigned i;
-       int ret = 0;
+               ret = pread(fd, eb->data, cur_len, cur_off);
+               if (ret < cur_len) {
+                       ret = (ret < 0 ? ret : -EIO);
+                       free(eb);
+                       break;
+               }
+               eb->start = key.objectid;
+               eb->len = key.offset;
 
-       offset = fs->super->s_first_data_block;
-       offset /= EXT2FS_CLUSTER_RATIO(fs);
-       offset += group_nr * EXT2_CLUSTERS_PER_GROUP(fs->super);
-       for (i = 0; i < EXT2_CLUSTERS_PER_GROUP(fs->super); i++) {
-               if (ext2fs_test_bit(i, bitmap)) {
-                       u64 start;
+               /* Write the data */
+               ret = write_and_map_eb(trans, root, eb);
+               free(eb);
+               if (ret < 0)
+                       break;
 
-                       start = (i + offset) * EXT2FS_CLUSTER_RATIO(fs);
-                       start *= fs->blocksize;
-                       ret = add_merge_cache_extent(used, start,
-                                                    fs->blocksize);
+               /* Now handle extent item and file extent things */
+               ret = btrfs_record_file_extent(trans, root, ino, inode, cur_off,
+                                              key.objectid, key.offset);
+               if (ret < 0)
+                       break;
+               /* Finally, insert csum items */
+               if (datacsum)
+                       ret = csum_disk_extent(trans, root, key.objectid,
+                                              key.offset);
+
+               /* Don't forget to insert hole */
+               hole_len = cur_off - hole_start;
+               if (hole_len) {
+                       ret = btrfs_record_file_extent(trans, root, ino, inode,
+                                       hole_start, 0, hole_len);
                        if (ret < 0)
                                break;
                }
+
+               cur_off += key.offset;
+               hole_start = cur_off;
+               cur_len = start + len - cur_off;
        }
+       /* Last hole */
+       if (start + len - hole_start > 0)
+               ret = btrfs_record_file_extent(trans, root, ino, inode,
+                               hole_start, 0, start + len - hole_start);
        return ret;
 }
 
 /*
- * Read all used ext2 space into cctx->used cache tree
+ * Relocate the used ext2 data in reserved ranges
+ * [0,1M)
+ * [btrfs_sb_offset(1), +BTRFS_STRIPE_LEN)
+ * [btrfs_sb_offset(2), +BTRFS_STRIPE_LEN)
  */
-static int ext2_read_used_space(struct btrfs_convert_context *cctx)
+static int migrate_reserved_ranges(struct btrfs_trans_handle *trans,
+                                  struct btrfs_root *root,
+                                  struct cache_tree *used,
+                                  struct btrfs_inode_item *inode, int fd,
+                                  u64 ino, u64 total_bytes, int datacsum)
 {
-       ext2_filsys fs = (ext2_filsys)cctx->fs_data;
-       blk64_t blk_itr = EXT2FS_B2C(fs, fs->super->s_first_data_block);
-       struct cache_tree *used_tree = &cctx->used;
-       char *block_bitmap = NULL;
-       unsigned long i;
-       int block_nbytes;
+       u64 cur_off;
+       u64 cur_len;
        int ret = 0;
 
-       block_nbytes = EXT2_CLUSTERS_PER_GROUP(fs->super) / 8;
-       /* Shouldn't happen */
-       BUG_ON(!fs->block_map);
-
-       block_bitmap = malloc(block_nbytes);
-       if (!block_bitmap)
-               return -ENOMEM;
+       /* 0 ~ 1M */
+       cur_off = 0;
+       cur_len = 1024 * 1024;
+       ret = migrate_one_reserved_range(trans, root, used, inode, fd, ino,
+                                        cur_off, cur_len, datacsum);
+       if (ret < 0)
+               return ret;
 
-       for (i = 0; i < fs->group_desc_count; i++) {
-               ret = ext2fs_get_block_bitmap_range(fs->block_map, blk_itr,
-                                               block_nbytes * 8, block_bitmap);
-               if (ret) {
-                       error("fail to get bitmap from ext2, %s",
-                             strerror(-ret));
-                       break;
-               }
-               ret = __ext2_add_one_block(fs, block_bitmap, i, used_tree);
-               if (ret < 0) {
-                       error("fail to build used space tree, %s",
-                             strerror(-ret));
-                       break;
-               }
-               blk_itr += EXT2_CLUSTERS_PER_GROUP(fs->super);
-       }
+       /* second sb(fisrt sb is included in 0~1M) */
+       cur_off = btrfs_sb_offset(1);
+       cur_len = min(total_bytes, cur_off + BTRFS_STRIPE_LEN) - cur_off;
+       if (cur_off > total_bytes)
+               return ret;
+       ret = migrate_one_reserved_range(trans, root, used, inode, fd, ino,
+                                        cur_off, cur_len, datacsum);
+       if (ret < 0)
+               return ret;
 
-       free(block_bitmap);
+       /* Last sb */
+       cur_off = btrfs_sb_offset(2);
+       cur_len = min(total_bytes, cur_off + BTRFS_STRIPE_LEN) - cur_off;
+       if (cur_off > total_bytes)
+               return ret;
+       ret = migrate_one_reserved_range(trans, root, used, inode, fd, ino,
+                                        cur_off, cur_len, datacsum);
        return ret;
 }
 
-static void ext2_close_fs(struct btrfs_convert_context *cctx)
+/*
+ * Helper for expand and merge extent_cache for wipe_one_reserved_range() to
+ * handle wiping a range that exists in cache.
+ */
+static int _expand_extent_cache(struct cache_tree *tree,
+                               struct cache_extent *entry,
+                               u64 min_stripe_size, int backward)
 {
-       if (cctx->volume_name) {
-               free(cctx->volume_name);
-               cctx->volume_name = NULL;
-       }
-       ext2fs_close(cctx->fs_data);
-}
+       struct cache_extent *ce;
+       int diff;
 
-struct dir_iterate_data {
-       struct btrfs_trans_handle *trans;
-       struct btrfs_root *root;
-       struct btrfs_inode_item *inode;
-       u64 objectid;
-       u64 index_cnt;
-       u64 parent;
-       int errcode;
-};
-
-static u8 ext2_filetype_conversion_table[EXT2_FT_MAX] = {
-       [EXT2_FT_UNKNOWN]       = BTRFS_FT_UNKNOWN,
-       [EXT2_FT_REG_FILE]      = BTRFS_FT_REG_FILE,
-       [EXT2_FT_DIR]           = BTRFS_FT_DIR,
-       [EXT2_FT_CHRDEV]        = BTRFS_FT_CHRDEV,
-       [EXT2_FT_BLKDEV]        = BTRFS_FT_BLKDEV,
-       [EXT2_FT_FIFO]          = BTRFS_FT_FIFO,
-       [EXT2_FT_SOCK]          = BTRFS_FT_SOCK,
-       [EXT2_FT_SYMLINK]       = BTRFS_FT_SYMLINK,
-};
-
-static int ext2_dir_iterate_proc(ext2_ino_t dir, int entry,
-                           struct ext2_dir_entry *dirent,
-                           int offset, int blocksize,
-                           char *buf,void *priv_data)
-{
-       int ret;
-       int file_type;
-       u64 objectid;
-       char dotdot[] = "..";
-       struct dir_iterate_data *idata = (struct dir_iterate_data *)priv_data;
-       int name_len;
-
-       name_len = dirent->name_len & 0xFF;
+       if (entry->size >= min_stripe_size)
+               return 0;
+       diff = min_stripe_size - entry->size;
 
-       objectid = dirent->inode + INO_OFFSET;
-       if (!strncmp(dirent->name, dotdot, name_len)) {
-               if (name_len == 2) {
-                       BUG_ON(idata->parent != 0);
-                       idata->parent = objectid;
+       if (backward) {
+               ce = prev_cache_extent(entry);
+               if (!ce)
+                       goto expand_back;
+               if (ce->start + ce->size >= entry->start - diff) {
+                       /* Directly merge with previous extent */
+                       ce->size = entry->start + entry->size - ce->start;
+                       remove_cache_extent(tree, entry);
+                       free(entry);
+                       return 0;
+               }
+expand_back:
+               /* No overlap, normal extent */
+               if (entry->start < diff) {
+                       error("cannot find space for data chunk layout");
+                       return -ENOSPC;
                }
+               entry->start -= diff;
+               entry->size += diff;
                return 0;
        }
-       if (dirent->inode < EXT2_GOOD_OLD_FIRST_INO)
+       ce = next_cache_extent(entry);
+       if (!ce)
+               goto expand_after;
+       if (entry->start + entry->size + diff >= ce->start) {
+               /* Directly merge with next extent */
+               entry->size = ce->start + ce->size - entry->start;
+               remove_cache_extent(tree, ce);
+               free(ce);
                return 0;
-
-       file_type = dirent->name_len >> 8;
-       BUG_ON(file_type > EXT2_FT_SYMLINK);
-
-       ret = convert_insert_dirent(idata->trans, idata->root, dirent->name,
-                                   name_len, idata->objectid, objectid,
-                                   ext2_filetype_conversion_table[file_type],
-                                   idata->index_cnt, idata->inode);
-       if (ret < 0) {
-               idata->errcode = ret;
-               return BLOCK_ABORT;
        }
-
-       idata->index_cnt++;
+expand_after:
+       entry->size += diff;
        return 0;
 }
 
-static int ext2_create_dir_entries(struct btrfs_trans_handle *trans,
-                             struct btrfs_root *root, u64 objectid,
-                             struct btrfs_inode_item *btrfs_inode,
-                             ext2_filsys ext2_fs, ext2_ino_t ext2_ino)
+/*
+ * Remove one reserve range from given cache tree
+ * if min_stripe_size is non-zero, it will ensure for split case,
+ * all its split cache extent is no smaller than @min_strip_size / 2.
+ */
+static int wipe_one_reserved_range(struct cache_tree *tree,
+                                  u64 start, u64 len, u64 min_stripe_size,
+                                  int ensure_size)
 {
+       struct cache_extent *cache;
        int ret;
-       errcode_t err;
-       struct dir_iterate_data data = {
-               .trans          = trans,
-               .root           = root,
-               .inode          = btrfs_inode,
-               .objectid       = objectid,
-               .index_cnt      = 2,
-               .parent         = 0,
-               .errcode        = 0,
-       };
 
-       err = ext2fs_dir_iterate2(ext2_fs, ext2_ino, 0, NULL,
-                                 ext2_dir_iterate_proc, &data);
-       if (err)
-               goto error;
-       ret = data.errcode;
-       if (ret == 0 && data.parent == objectid) {
-               ret = btrfs_insert_inode_ref(trans, root, "..", 2,
-                                            objectid, objectid, 0);
-       }
-       return ret;
-error:
-       fprintf(stderr, "ext2fs_dir_iterate2: %s\n", error_message(err));
-       return -1;
-}
+       BUG_ON(ensure_size && min_stripe_size == 0);
+       /*
+        * The logical here is simplified to handle special cases only
+        * So we don't need to consider merge case for ensure_size
+        */
+       BUG_ON(min_stripe_size && (min_stripe_size < len * 2 ||
+              min_stripe_size / 2 < BTRFS_STRIPE_LEN));
 
-static int ext2_block_iterate_proc(ext2_filsys fs, blk_t *blocknr,
-                               e2_blkcnt_t blockcnt, blk_t ref_block,
-                               int ref_offset, void *priv_data)
-{
-       int ret;
-       struct blk_iterate_data *idata;
-       idata = (struct blk_iterate_data *)priv_data;
-       ret = block_iterate_proc(*blocknr, blockcnt, idata);
-       if (ret) {
-               idata->errcode = ret;
-               return BLOCK_ABORT;
+       /* Also, wipe range should already be aligned */
+       BUG_ON(start != round_down(start, BTRFS_STRIPE_LEN) ||
+              start + len != round_up(start + len, BTRFS_STRIPE_LEN));
+
+       min_stripe_size /= 2;
+
+       cache = lookup_cache_extent(tree, start, len);
+       if (!cache)
+               return 0;
+
+       if (start <= cache->start) {
+               /*
+                *      |--------cache---------|
+                * |-wipe-|
+                */
+               BUG_ON(start + len <= cache->start);
+
+               /*
+                * The wipe size is smaller than min_stripe_size / 2,
+                * so the result length should still meet min_stripe_size
+                * And no need to do alignment
+                */
+               cache->size -= (start + len - cache->start);
+               if (cache->size == 0) {
+                       remove_cache_extent(tree, cache);
+                       free(cache);
+                       return 0;
+               }
+
+               BUG_ON(ensure_size && cache->size < min_stripe_size);
+
+               cache->start = start + len;
+               return 0;
+       } else if (start > cache->start && start + len < cache->start +
+                  cache->size) {
+               /*
+                * |-------cache-----|
+                *      |-wipe-|
+                */
+               u64 old_start = cache->start;
+               u64 old_len = cache->size;
+               u64 insert_start = start + len;
+               u64 insert_len;
+
+               cache->size = start - cache->start;
+               /* Expand the leading half part if needed */
+               if (ensure_size && cache->size < min_stripe_size) {
+                       ret = _expand_extent_cache(tree, cache,
+                                       min_stripe_size, 1);
+                       if (ret < 0)
+                               return ret;
+               }
+
+               /* And insert the new one */
+               insert_len = old_start + old_len - start - len;
+               ret = add_merge_cache_extent(tree, insert_start, insert_len);
+               if (ret < 0)
+                       return ret;
+
+               /* Expand the last half part if needed */
+               if (ensure_size && insert_len < min_stripe_size) {
+                       cache = lookup_cache_extent(tree, insert_start,
+                                                   insert_len);
+                       if (!cache || cache->start != insert_start ||
+                           cache->size != insert_len)
+                               return -ENOENT;
+                       ret = _expand_extent_cache(tree, cache,
+                                       min_stripe_size, 0);
+               }
+
+               return ret;
        }
+       /*
+        * |----cache-----|
+        *              |--wipe-|
+        * Wipe len should be small enough and no need to expand the
+        * remaining extent
+        */
+       cache->size = start - cache->start;
+       BUG_ON(ensure_size && cache->size < min_stripe_size);
        return 0;
 }
 
 /*
- * traverse file's data blocks, record these data blocks as file extents.
+ * Remove reserved ranges from given cache_tree
+ *
+ * It will remove the following ranges
+ * 1) 0~1M
+ * 2) 2nd superblock, +64K (make sure chunks are 64K aligned)
+ * 3) 3rd superblock, +64K
+ *
+ * @min_stripe must be given for safety check
+ * and if @ensure_size is given, it will ensure affected cache_extent will be
+ * larger than min_stripe_size
  */
-static int ext2_create_file_extents(struct btrfs_trans_handle *trans,
-                              struct btrfs_root *root, u64 objectid,
-                              struct btrfs_inode_item *btrfs_inode,
-                              ext2_filsys ext2_fs, ext2_ino_t ext2_ino,
-                              int datacsum, int packing)
+static int wipe_reserved_ranges(struct cache_tree *tree, u64 min_stripe_size,
+                               int ensure_size)
 {
        int ret;
-       char *buffer = NULL;
-       errcode_t err;
-       u32 last_block;
-       u32 sectorsize = root->sectorsize;
-       u64 inode_size = btrfs_stack_inode_size(btrfs_inode);
-       struct blk_iterate_data data;
 
-       init_blk_iterate_data(&data, trans, root, btrfs_inode, objectid,
-                             datacsum);
+       ret = wipe_one_reserved_range(tree, 0, 1024 * 1024, min_stripe_size,
+                                     ensure_size);
+       if (ret < 0)
+               return ret;
+       ret = wipe_one_reserved_range(tree, btrfs_sb_offset(1),
+                       BTRFS_STRIPE_LEN, min_stripe_size, ensure_size);
+       if (ret < 0)
+               return ret;
+       ret = wipe_one_reserved_range(tree, btrfs_sb_offset(2),
+                       BTRFS_STRIPE_LEN, min_stripe_size, ensure_size);
+       return ret;
+}
 
-       err = ext2fs_block_iterate2(ext2_fs, ext2_ino, BLOCK_FLAG_DATA_ONLY,
-                                   NULL, ext2_block_iterate_proc, &data);
-       if (err)
-               goto error;
-       ret = data.errcode;
-       if (ret)
-               goto fail;
-       if (packing && data.first_block == 0 && data.num_blocks > 0 &&
-           inode_size <= BTRFS_MAX_INLINE_DATA_SIZE(root)) {
-               u64 num_bytes = data.num_blocks * sectorsize;
-               u64 disk_bytenr = data.disk_block * sectorsize;
-               u64 nbytes;
+static int calculate_available_space(struct btrfs_convert_context *cctx)
+{
+       struct cache_tree *used = &cctx->used;
+       struct cache_tree *data_chunks = &cctx->data_chunks;
+       struct cache_tree *free = &cctx->free;
+       struct cache_extent *cache;
+       u64 cur_off = 0;
+       /*
+        * Twice the minimal chunk size, to allow later wipe_reserved_ranges()
+        * works without need to consider overlap
+        */
+       u64 min_stripe_size = 2 * 16 * 1024 * 1024;
+       int ret;
 
-               buffer = malloc(num_bytes);
-               if (!buffer)
-                       return -ENOMEM;
-               ret = read_disk_extent(root, disk_bytenr, num_bytes, buffer);
-               if (ret)
-                       goto fail;
-               if (num_bytes > inode_size)
-                       num_bytes = inode_size;
-               ret = btrfs_insert_inline_extent(trans, root, objectid,
-                                                0, buffer, num_bytes);
-               if (ret)
-                       goto fail;
-               nbytes = btrfs_stack_inode_nbytes(btrfs_inode) + num_bytes;
-               btrfs_set_stack_inode_nbytes(btrfs_inode, nbytes);
-       } else if (data.num_blocks > 0) {
-               ret = record_file_blocks(&data, data.first_block,
-                                        data.disk_block, data.num_blocks);
-               if (ret)
-                       goto fail;
+       /* Calculate data_chunks */
+       for (cache = first_cache_extent(used); cache;
+            cache = next_cache_extent(cache)) {
+               u64 cur_len;
+
+               if (cache->start + cache->size < cur_off)
+                       continue;
+               if (cache->start > cur_off + min_stripe_size)
+                       cur_off = cache->start;
+               cur_len = max(cache->start + cache->size - cur_off,
+                             min_stripe_size);
+               ret = add_merge_cache_extent(data_chunks, cur_off, cur_len);
+               if (ret < 0)
+                       goto out;
+               cur_off += cur_len;
        }
-       data.first_block += data.num_blocks;
-       last_block = (inode_size + sectorsize - 1) / sectorsize;
-       if (last_block > data.first_block) {
-               ret = record_file_blocks(&data, data.first_block, 0,
-                                        last_block - data.first_block);
+       /*
+        * remove reserved ranges, so we won't ever bother relocating an old
+        * filesystem extent to other place.
+        */
+       ret = wipe_reserved_ranges(data_chunks, min_stripe_size, 1);
+       if (ret < 0)
+               goto out;
+
+       cur_off = 0;
+       /*
+        * Calculate free space
+        * Always round up the start bytenr, to avoid metadata extent corss
+        * stripe boundary, as later mkfs_convert() won't have all the extent
+        * allocation check
+        */
+       for (cache = first_cache_extent(data_chunks); cache;
+            cache = next_cache_extent(cache)) {
+               if (cache->start < cur_off)
+                       continue;
+               if (cache->start > cur_off) {
+                       u64 insert_start;
+                       u64 len;
+
+                       len = cache->start - round_up(cur_off,
+                                                     BTRFS_STRIPE_LEN);
+                       insert_start = round_up(cur_off, BTRFS_STRIPE_LEN);
+
+                       ret = add_merge_cache_extent(free, insert_start, len);
+                       if (ret < 0)
+                               goto out;
+               }
+               cur_off = cache->start + cache->size;
        }
-fail:
-       free(buffer);
+       /* Don't forget the last range */
+       if (cctx->total_bytes > cur_off) {
+               u64 len = cctx->total_bytes - cur_off;
+               u64 insert_start;
+
+               insert_start = round_up(cur_off, BTRFS_STRIPE_LEN);
+
+               ret = add_merge_cache_extent(free, insert_start, len);
+               if (ret < 0)
+                       goto out;
+       }
+
+       /* Remove reserved bytes */
+       ret = wipe_reserved_ranges(free, min_stripe_size, 0);
+out:
        return ret;
-error:
-       fprintf(stderr, "ext2fs_block_iterate2: %s\n", error_message(err));
-       return -1;
 }
 
-static int ext2_create_symbol_link(struct btrfs_trans_handle *trans,
                            struct btrfs_root *root, u64 objectid,
-                             struct btrfs_inode_item *btrfs_inode,
-                             ext2_filsys ext2_fs, ext2_ino_t ext2_ino,
-                             struct ext2_inode *ext2_inode)
+/*
* Read used space, and since we have the used space,
+ * calcuate data_chunks and free for later mkfs
+ */
+static int convert_read_used_space(struct btrfs_convert_context *cctx)
 {
        int ret;
-       char *pathname;
-       u64 inode_size = btrfs_stack_inode_size(btrfs_inode);
-       if (ext2fs_inode_data_blocks(ext2_fs, ext2_inode)) {
-               btrfs_set_stack_inode_size(btrfs_inode, inode_size + 1);
-               ret = ext2_create_file_extents(trans, root, objectid,
-                               btrfs_inode, ext2_fs, ext2_ino, 1, 1);
-               btrfs_set_stack_inode_size(btrfs_inode, inode_size);
+
+       ret = cctx->convert_ops->read_used_space(cctx);
+       if (ret)
                return ret;
-       }
 
-       pathname = (char *)&(ext2_inode->i_block[0]);
-       BUG_ON(pathname[inode_size] != 0);
-       ret = btrfs_insert_inline_extent(trans, root, objectid, 0,
-                                        pathname, inode_size + 1);
-       btrfs_set_stack_inode_nbytes(btrfs_inode, inode_size + 1);
+       ret = calculate_available_space(cctx);
        return ret;
 }
 
 /*
- * Following xattr/acl related codes are based on codes in
- * fs/ext3/xattr.c and fs/ext3/acl.c
+ * Create the fs image file of old filesystem.
+ *
+ * This is completely fs independent as we have cctx->used, only
+ * need to create file extents pointing to all the positions.
  */
-#define EXT2_XATTR_BHDR(ptr) ((struct ext2_ext_attr_header *)(ptr))
-#define EXT2_XATTR_BFIRST(ptr) \
-       ((struct ext2_ext_attr_entry *)(EXT2_XATTR_BHDR(ptr) + 1))
-#define EXT2_XATTR_IHDR(inode) \
-       ((struct ext2_ext_attr_header *) ((void *)(inode) + \
-               EXT2_GOOD_OLD_INODE_SIZE + (inode)->i_extra_isize))
-#define EXT2_XATTR_IFIRST(inode) \
-       ((struct ext2_ext_attr_entry *) ((void *)EXT2_XATTR_IHDR(inode) + \
-               sizeof(EXT2_XATTR_IHDR(inode)->h_magic)))
-
-static int ext2_xattr_check_names(struct ext2_ext_attr_entry *entry,
-                                 const void *end)
+static int create_image(struct btrfs_root *root,
+                          struct btrfs_mkfs_config *cfg,
+                          struct btrfs_convert_context *cctx, int fd,
+                          u64 size, char *name, int datacsum)
 {
-       struct ext2_ext_attr_entry *next;
+       struct btrfs_inode_item buf;
+       struct btrfs_trans_handle *trans;
+       struct btrfs_path path;
+       struct btrfs_key key;
+       struct cache_extent *cache;
+       struct cache_tree used_tmp;
+       u64 cur;
+       u64 ino;
+       u64 flags = BTRFS_INODE_READONLY;
+       int ret;
 
-       while (!EXT2_EXT_IS_LAST_ENTRY(entry)) {
-               next = EXT2_EXT_ATTR_NEXT(entry);
-               if ((void *)next >= end)
-                       return -EIO;
-               entry = next;
-       }
-       return 0;
-}
+       if (!datacsum)
+               flags |= BTRFS_INODE_NODATASUM;
 
-static int ext2_xattr_check_block(const char *buf, size_t size)
-{
-       int error;
-       struct ext2_ext_attr_header *header = EXT2_XATTR_BHDR(buf);
+       trans = btrfs_start_transaction(root, 1);
+       if (!trans)
+               return -ENOMEM;
 
-       if (header->h_magic != EXT2_EXT_ATTR_MAGIC ||
-           header->h_blocks != 1)
-               return -EIO;
-       error = ext2_xattr_check_names(EXT2_XATTR_BFIRST(buf), buf + size);
-       return error;
-}
+       cache_tree_init(&used_tmp);
+       btrfs_init_path(&path);
 
-static int ext2_xattr_check_entry(struct ext2_ext_attr_entry *entry,
-                                 size_t size)
-{
-       size_t value_size = entry->e_value_size;
+       ret = btrfs_find_free_objectid(trans, root, BTRFS_FIRST_FREE_OBJECTID,
+                                      &ino);
+       if (ret < 0)
+               goto out;
+       ret = btrfs_new_inode(trans, root, ino, 0400 | S_IFREG);
+       if (ret < 0)
+               goto out;
+       ret = btrfs_change_inode_flags(trans, root, ino, flags);
+       if (ret < 0)
+               goto out;
+       ret = btrfs_add_link(trans, root, ino, BTRFS_FIRST_FREE_OBJECTID, name,
+                            strlen(name), BTRFS_FT_REG_FILE, NULL, 1);
+       if (ret < 0)
+               goto out;
 
-       if (entry->e_value_block != 0 || value_size > size ||
-           entry->e_value_offs + value_size > size)
-               return -EIO;
-       return 0;
-}
+       key.objectid = ino;
+       key.type = BTRFS_INODE_ITEM_KEY;
+       key.offset = 0;
 
-#define EXT2_ACL_VERSION       0x0001
+       ret = btrfs_search_slot(trans, root, &key, &path, 0, 1);
+       if (ret) {
+               ret = (ret > 0 ? -ENOENT : ret);
+               goto out;
+       }
+       read_extent_buffer(path.nodes[0], &buf,
+                       btrfs_item_ptr_offset(path.nodes[0], path.slots[0]),
+                       sizeof(buf));
+       btrfs_release_path(&path);
 
-/* 23.2.5 acl_tag_t values */
+       /*
+        * Create a new used space cache, which doesn't contain the reserved
+        * range
+        */
+       for (cache = first_cache_extent(&cctx->used); cache;
+            cache = next_cache_extent(cache)) {
+               ret = add_cache_extent(&used_tmp, cache->start, cache->size);
+               if (ret < 0)
+                       goto out;
+       }
+       ret = wipe_reserved_ranges(&used_tmp, 0, 0);
+       if (ret < 0)
+               goto out;
 
-#define ACL_UNDEFINED_TAG       (0x00)
-#define ACL_USER_OBJ            (0x01)
-#define ACL_USER                (0x02)
-#define ACL_GROUP_OBJ           (0x04)
-#define ACL_GROUP               (0x08)
-#define ACL_MASK                (0x10)
-#define ACL_OTHER               (0x20)
+       /*
+        * Start from 1M, as 0~1M is reserved, and create_image_file_range()
+        * can't handle bytenr 0(will consider it as a hole)
+        */
+       cur = 1024 * 1024;
+       while (cur < size) {
+               u64 len = size - cur;
 
-/* 23.2.7 ACL qualifier constants */
-
-#define ACL_UNDEFINED_ID        ((id_t)-1)
-
-typedef struct {
-       __le16          e_tag;
-       __le16          e_perm;
-       __le32          e_id;
-} ext2_acl_entry;
-
-typedef struct {
-       __le16          e_tag;
-       __le16          e_perm;
-} ext2_acl_entry_short;
+               ret = create_image_file_range(trans, root, &used_tmp,
+                                               &buf, ino, cur, &len, datacsum);
+               if (ret < 0)
+                       goto out;
+               cur += len;
+       }
+       /* Handle the reserved ranges */
+       ret = migrate_reserved_ranges(trans, root, &cctx->used, &buf, fd, ino,
+                                     cfg->num_bytes, datacsum);
 
-typedef struct {
-       __le32          a_version;
-} ext2_acl_header;
 
-static inline int ext2_acl_count(size_t size)
-{
-       ssize_t s;
-       size -= sizeof(ext2_acl_header);
-       s = size - 4 * sizeof(ext2_acl_entry_short);
-       if (s < 0) {
-               if (size % sizeof(ext2_acl_entry_short))
-                       return -1;
-               return size / sizeof(ext2_acl_entry_short);
-       } else {
-               if (s % sizeof(ext2_acl_entry))
-                       return -1;
-               return s / sizeof(ext2_acl_entry) + 4;
+       key.objectid = ino;
+       key.type = BTRFS_INODE_ITEM_KEY;
+       key.offset = 0;
+       ret = btrfs_search_slot(trans, root, &key, &path, 0, 1);
+       if (ret) {
+               ret = (ret > 0 ? -ENOENT : ret);
+               goto out;
        }
+       btrfs_set_stack_inode_size(&buf, cfg->num_bytes);
+       write_extent_buffer(path.nodes[0], &buf,
+                       btrfs_item_ptr_offset(path.nodes[0], path.slots[0]),
+                       sizeof(buf));
+out:
+       free_extent_cache_tree(&used_tmp);
+       btrfs_release_path(&path);
+       btrfs_commit_transaction(trans, root);
+       return ret;
 }
 
-#define ACL_EA_VERSION         0x0002
+static struct btrfs_root* link_subvol(struct btrfs_root *root,
+               const char *base, u64 root_objectid)
+{
+       struct btrfs_trans_handle *trans;
+       struct btrfs_fs_info *fs_info = root->fs_info;
+       struct btrfs_root *tree_root = fs_info->tree_root;
+       struct btrfs_root *new_root = NULL;
+       struct btrfs_path path;
+       struct btrfs_inode_item *inode_item;
+       struct extent_buffer *leaf;
+       struct btrfs_key key;
+       u64 dirid = btrfs_root_dirid(&root->root_item);
+       u64 index = 2;
+       char buf[BTRFS_NAME_LEN + 1]; /* for snprintf null */
+       int len;
+       int i;
+       int ret;
 
-typedef struct {
-       __le16          e_tag;
-       __le16          e_perm;
-       __le32          e_id;
-} acl_ea_entry;
+       len = strlen(base);
+       if (len == 0 || len > BTRFS_NAME_LEN)
+               return NULL;
 
-typedef struct {
-       __le32          a_version;
-       acl_ea_entry    a_entries[0];
-} acl_ea_header;
+       btrfs_init_path(&path);
+       key.objectid = dirid;
+       key.type = BTRFS_DIR_INDEX_KEY;
+       key.offset = (u64)-1;
 
-static inline size_t acl_ea_size(int count)
-{
-       return sizeof(acl_ea_header) + count * sizeof(acl_ea_entry);
-}
+       ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+       if (ret <= 0) {
+               error("search for DIR_INDEX dirid %llu failed: %d",
+                               (unsigned long long)dirid, ret);
+               goto fail;
+       }
 
-static int ext2_acl_to_xattr(void *dst, const void *src,
-                            size_t dst_size, size_t src_size)
-{
-       int i, count;
-       const void *end = src + src_size;
-       acl_ea_header *ext_acl = (acl_ea_header *)dst;
-       acl_ea_entry *dst_entry = ext_acl->a_entries;
-       ext2_acl_entry *src_entry;
+       if (path.slots[0] > 0) {
+               path.slots[0]--;
+               btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
+               if (key.objectid == dirid && key.type == BTRFS_DIR_INDEX_KEY)
+                       index = key.offset + 1;
+       }
+       btrfs_release_path(&path);
 
-       if (src_size < sizeof(ext2_acl_header))
-               goto fail;
-       if (((ext2_acl_header *)src)->a_version !=
-           cpu_to_le32(EXT2_ACL_VERSION))
+       trans = btrfs_start_transaction(root, 1);
+       if (!trans) {
+               error("unable to start transaction");
                goto fail;
-       src += sizeof(ext2_acl_header);
-       count = ext2_acl_count(src_size);
-       if (count <= 0)
+       }
+
+       key.objectid = dirid;
+       key.offset = 0;
+       key.type =  BTRFS_INODE_ITEM_KEY;
+
+       ret = btrfs_lookup_inode(trans, root, &path, &key, 1);
+       if (ret) {
+               error("search for INODE_ITEM %llu failed: %d",
+                               (unsigned long long)dirid, ret);
                goto fail;
+       }
+       leaf = path.nodes[0];
+       inode_item = btrfs_item_ptr(leaf, path.slots[0],
+                                   struct btrfs_inode_item);
 
-       BUG_ON(dst_size < acl_ea_size(count));
-       ext_acl->a_version = cpu_to_le32(ACL_EA_VERSION);
-       for (i = 0; i < count; i++, dst_entry++) {
-               src_entry = (ext2_acl_entry *)src;
-               if (src + sizeof(ext2_acl_entry_short) > end)
-                       goto fail;
-               dst_entry->e_tag = src_entry->e_tag;
-               dst_entry->e_perm = src_entry->e_perm;
-               switch (le16_to_cpu(src_entry->e_tag)) {
-               case ACL_USER_OBJ:
-               case ACL_GROUP_OBJ:
-               case ACL_MASK:
-               case ACL_OTHER:
-                       src += sizeof(ext2_acl_entry_short);
-                       dst_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
+       key.objectid = root_objectid;
+       key.offset = (u64)-1;
+       key.type = BTRFS_ROOT_ITEM_KEY;
+
+       memcpy(buf, base, len);
+       for (i = 0; i < 1024; i++) {
+               ret = btrfs_insert_dir_item(trans, root, buf, len,
+                                           dirid, &key, BTRFS_FT_DIR, index);
+               if (ret != -EEXIST)
                        break;
-               case ACL_USER:
-               case ACL_GROUP:
-                       src += sizeof(ext2_acl_entry);
-                       if (src > end)
-                               goto fail;
-                       dst_entry->e_id = src_entry->e_id;
+               len = snprintf(buf, ARRAY_SIZE(buf), "%s%d", base, i);
+               if (len < 1 || len > BTRFS_NAME_LEN) {
+                       ret = -EINVAL;
                        break;
-               default:
-                       goto fail;
                }
        }
-       if (src != end)
+       if (ret)
                goto fail;
-       return 0;
-fail:
-       return -EINVAL;
-}
 
-static char *xattr_prefix_table[] = {
-       [1] =   "user.",
-       [2] =   "system.posix_acl_access",
-       [3] =   "system.posix_acl_default",
-       [4] =   "trusted.",
-       [6] =   "security.",
-};
+       btrfs_set_inode_size(leaf, inode_item, len * 2 +
+                            btrfs_inode_size(leaf, inode_item));
+       btrfs_mark_buffer_dirty(leaf);
+       btrfs_release_path(&path);
 
-static int ext2_copy_single_xattr(struct btrfs_trans_handle *trans,
-                            struct btrfs_root *root, u64 objectid,
-                            struct ext2_ext_attr_entry *entry,
-                            const void *data, u32 datalen)
-{
-       int ret = 0;
-       int name_len;
-       int name_index;
-       void *databuf = NULL;
-       char namebuf[XATTR_NAME_MAX + 1];
+       /* add the backref first */
+       ret = btrfs_add_root_ref(trans, tree_root, root_objectid,
+                                BTRFS_ROOT_BACKREF_KEY,
+                                root->root_key.objectid,
+                                dirid, index, buf, len);
+       if (ret) {
+               error("unable to add root backref for %llu: %d",
+                               root->root_key.objectid, ret);
+               goto fail;
+       }
 
-       name_index = entry->e_name_index;
-       if (name_index >= ARRAY_SIZE(xattr_prefix_table) ||
-           xattr_prefix_table[name_index] == NULL)
-               return -EOPNOTSUPP;
-       name_len = strlen(xattr_prefix_table[name_index]) +
-                  entry->e_name_len;
-       if (name_len >= sizeof(namebuf))
-               return -ERANGE;
+       /* now add the forward ref */
+       ret = btrfs_add_root_ref(trans, tree_root, root->root_key.objectid,
+                                BTRFS_ROOT_REF_KEY, root_objectid,
+                                dirid, index, buf, len);
+       if (ret) {
+               error("unable to add root ref for %llu: %d",
+                               root->root_key.objectid, ret);
+               goto fail;
+       }
 
-       if (name_index == 2 || name_index == 3) {
-               size_t bufsize = acl_ea_size(ext2_acl_count(datalen));
-               databuf = malloc(bufsize);
-               if (!databuf)
-                      return -ENOMEM;
-               ret = ext2_acl_to_xattr(databuf, data, bufsize, datalen);
-               if (ret)
-                       goto out;
-               data = databuf;
-               datalen = bufsize;
+       ret = btrfs_commit_transaction(trans, root);
+       if (ret) {
+               error("transaction commit failed: %d", ret);
+               goto fail;
        }
-       strncpy(namebuf, xattr_prefix_table[name_index], XATTR_NAME_MAX);
-       strncat(namebuf, EXT2_EXT_ATTR_NAME(entry), entry->e_name_len);
-       if (name_len + datalen > BTRFS_LEAF_DATA_SIZE(root) -
-           sizeof(struct btrfs_item) - sizeof(struct btrfs_dir_item)) {
-               fprintf(stderr, "skip large xattr on inode %Lu name %.*s\n",
-                       objectid - INO_OFFSET, name_len, namebuf);
-               goto out;
+
+       new_root = btrfs_read_fs_root(fs_info, &key);
+       if (IS_ERR(new_root)) {
+               error("unable to fs read root: %lu", PTR_ERR(new_root));
+               new_root = NULL;
        }
-       ret = btrfs_insert_xattr_item(trans, root, namebuf, name_len,
-                                     data, datalen, objectid);
-out:
-       free(databuf);
-       return ret;
+fail:
+       btrfs_init_path(&path);
+       return new_root;
 }
 
-static int ext2_copy_extended_attrs(struct btrfs_trans_handle *trans,
-                              struct btrfs_root *root, u64 objectid,
-                              struct btrfs_inode_item *btrfs_inode,
-                              ext2_filsys ext2_fs, ext2_ino_t ext2_ino)
+static int create_subvol(struct btrfs_trans_handle *trans,
+                        struct btrfs_root *root, u64 root_objectid)
 {
-       int ret = 0;
-       int inline_ea = 0;
-       errcode_t err;
-       u32 datalen;
-       u32 block_size = ext2_fs->blocksize;
-       u32 inode_size = EXT2_INODE_SIZE(ext2_fs->super);
-       struct ext2_inode_large *ext2_inode;
-       struct ext2_ext_attr_entry *entry;
-       void *data;
-       char *buffer = NULL;
-       char inode_buf[EXT2_GOOD_OLD_INODE_SIZE];
-
-       if (inode_size <= EXT2_GOOD_OLD_INODE_SIZE) {
-               ext2_inode = (struct ext2_inode_large *)inode_buf;
-       } else {
-               ext2_inode = (struct ext2_inode_large *)malloc(inode_size);
-               if (!ext2_inode)
-                      return -ENOMEM;
-       }
-       err = ext2fs_read_inode_full(ext2_fs, ext2_ino, (void *)ext2_inode,
-                                    inode_size);
-       if (err) {
-               fprintf(stderr, "ext2fs_read_inode_full: %s\n",
-                       error_message(err));
-               ret = -1;
-               goto out;
-       }
+       struct extent_buffer *tmp;
+       struct btrfs_root *new_root;
+       struct btrfs_key key;
+       struct btrfs_root_item root_item;
+       int ret;
 
-       if (ext2_ino > ext2_fs->super->s_first_ino &&
-           inode_size > EXT2_GOOD_OLD_INODE_SIZE) {
-               if (EXT2_GOOD_OLD_INODE_SIZE +
-                   ext2_inode->i_extra_isize > inode_size) {
-                       ret = -EIO;
-                       goto out;
-               }
-               if (ext2_inode->i_extra_isize != 0 &&
-                   EXT2_XATTR_IHDR(ext2_inode)->h_magic ==
-                   EXT2_EXT_ATTR_MAGIC) {
-                       inline_ea = 1;
-               }
-       }
-       if (inline_ea) {
-               int total;
-               void *end = (void *)ext2_inode + inode_size;
-               entry = EXT2_XATTR_IFIRST(ext2_inode);
-               total = end - (void *)entry;
-               ret = ext2_xattr_check_names(entry, end);
-               if (ret)
-                       goto out;
-               while (!EXT2_EXT_IS_LAST_ENTRY(entry)) {
-                       ret = ext2_xattr_check_entry(entry, total);
-                       if (ret)
-                               goto out;
-                       data = (void *)EXT2_XATTR_IFIRST(ext2_inode) +
-                               entry->e_value_offs;
-                       datalen = entry->e_value_size;
-                       ret = ext2_copy_single_xattr(trans, root, objectid,
-                                               entry, data, datalen);
-                       if (ret)
-                               goto out;
-                       entry = EXT2_EXT_ATTR_NEXT(entry);
-               }
-       }
+       ret = btrfs_copy_root(trans, root, root->node, &tmp,
+                             root_objectid);
+       if (ret)
+               return ret;
 
-       if (ext2_inode->i_file_acl == 0)
-               goto out;
+       memcpy(&root_item, &root->root_item, sizeof(root_item));
+       btrfs_set_root_bytenr(&root_item, tmp->start);
+       btrfs_set_root_level(&root_item, btrfs_header_level(tmp));
+       btrfs_set_root_generation(&root_item, trans->transid);
+       free_extent_buffer(tmp);
 
-       buffer = malloc(block_size);
-       if (!buffer) {
-               ret = -ENOMEM;
-               goto out;
-       }
-       err = ext2fs_read_ext_attr(ext2_fs, ext2_inode->i_file_acl, buffer);
-       if (err) {
-               fprintf(stderr, "ext2fs_read_ext_attr: %s\n",
-                       error_message(err));
-               ret = -1;
-               goto out;
-       }
-       ret = ext2_xattr_check_block(buffer, block_size);
-       if (ret)
-               goto out;
+       key.objectid = root_objectid;
+       key.type = BTRFS_ROOT_ITEM_KEY;
+       key.offset = trans->transid;
+       ret = btrfs_insert_root(trans, root->fs_info->tree_root,
+                               &key, &root_item);
 
-       entry = EXT2_XATTR_BFIRST(buffer);
-       while (!EXT2_EXT_IS_LAST_ENTRY(entry)) {
-               ret = ext2_xattr_check_entry(entry, block_size);
-               if (ret)
-                       goto out;
-               data = buffer + entry->e_value_offs;
-               datalen = entry->e_value_size;
-               ret = ext2_copy_single_xattr(trans, root, objectid,
-                                       entry, data, datalen);
-               if (ret)
-                       goto out;
-               entry = EXT2_EXT_ATTR_NEXT(entry);
+       key.offset = (u64)-1;
+       new_root = btrfs_read_fs_root(root->fs_info, &key);
+       if (!new_root || IS_ERR(new_root)) {
+               error("unable to fs read root: %lu", PTR_ERR(new_root));
+               return PTR_ERR(new_root);
        }
-out:
-       free(buffer);
-       if ((void *)ext2_inode != inode_buf)
-               free(ext2_inode);
+
+       ret = btrfs_make_root_dir(trans, new_root, BTRFS_FIRST_FREE_OBJECTID);
+
        return ret;
 }
-#define MINORBITS      20
-#define MKDEV(ma, mi)  (((ma) << MINORBITS) | (mi))
 
-static inline dev_t old_decode_dev(u16 val)
+/*
+ * New make_btrfs() has handle system and meta chunks quite well.
+ * So only need to add remaining data chunks.
+ */
+static int make_convert_data_block_groups(struct btrfs_trans_handle *trans,
+                                         struct btrfs_fs_info *fs_info,
+                                         struct btrfs_mkfs_config *cfg,
+                                         struct btrfs_convert_context *cctx)
 {
-       return MKDEV((val >> 8) & 255, val & 255);
-}
+       struct btrfs_root *extent_root = fs_info->extent_root;
+       struct cache_tree *data_chunks = &cctx->data_chunks;
+       struct cache_extent *cache;
+       u64 max_chunk_size;
+       int ret = 0;
 
-static inline dev_t new_decode_dev(u32 dev)
-{
-       unsigned major = (dev & 0xfff00) >> 8;
-       unsigned minor = (dev & 0xff) | ((dev >> 12) & 0xfff00);
-       return MKDEV(major, minor);
-}
+       /*
+        * Don't create data chunk over 10% of the convert device
+        * And for single chunk, don't create chunk larger than 1G.
+        */
+       max_chunk_size = cfg->num_bytes / 10;
+       max_chunk_size = min((u64)(1024 * 1024 * 1024), max_chunk_size);
+       max_chunk_size = round_down(max_chunk_size, extent_root->sectorsize);
 
-static void ext2_copy_inode_item(struct btrfs_inode_item *dst,
-                          struct ext2_inode *src, u32 blocksize)
-{
-       btrfs_set_stack_inode_generation(dst, 1);
-       btrfs_set_stack_inode_sequence(dst, 0);
-       btrfs_set_stack_inode_transid(dst, 1);
-       btrfs_set_stack_inode_size(dst, src->i_size);
-       btrfs_set_stack_inode_nbytes(dst, 0);
-       btrfs_set_stack_inode_block_group(dst, 0);
-       btrfs_set_stack_inode_nlink(dst, src->i_links_count);
-       btrfs_set_stack_inode_uid(dst, src->i_uid | (src->i_uid_high << 16));
-       btrfs_set_stack_inode_gid(dst, src->i_gid | (src->i_gid_high << 16));
-       btrfs_set_stack_inode_mode(dst, src->i_mode);
-       btrfs_set_stack_inode_rdev(dst, 0);
-       btrfs_set_stack_inode_flags(dst, 0);
-       btrfs_set_stack_timespec_sec(&dst->atime, src->i_atime);
-       btrfs_set_stack_timespec_nsec(&dst->atime, 0);
-       btrfs_set_stack_timespec_sec(&dst->ctime, src->i_ctime);
-       btrfs_set_stack_timespec_nsec(&dst->ctime, 0);
-       btrfs_set_stack_timespec_sec(&dst->mtime, src->i_mtime);
-       btrfs_set_stack_timespec_nsec(&dst->mtime, 0);
-       btrfs_set_stack_timespec_sec(&dst->otime, 0);
-       btrfs_set_stack_timespec_nsec(&dst->otime, 0);
+       for (cache = first_cache_extent(data_chunks); cache;
+            cache = next_cache_extent(cache)) {
+               u64 cur = cache->start;
 
-       if (S_ISDIR(src->i_mode)) {
-               btrfs_set_stack_inode_size(dst, 0);
-               btrfs_set_stack_inode_nlink(dst, 1);
-       }
-       if (S_ISREG(src->i_mode)) {
-               btrfs_set_stack_inode_size(dst, (u64)src->i_size_high << 32 |
-                                          (u64)src->i_size);
-       }
-       if (!S_ISREG(src->i_mode) && !S_ISDIR(src->i_mode) &&
-           !S_ISLNK(src->i_mode)) {
-               if (src->i_block[0]) {
-                       btrfs_set_stack_inode_rdev(dst,
-                               old_decode_dev(src->i_block[0]));
-               } else {
-                       btrfs_set_stack_inode_rdev(dst,
-                               new_decode_dev(src->i_block[1]));
+               while (cur < cache->start + cache->size) {
+                       u64 len;
+                       u64 cur_backup = cur;
+
+                       len = min(max_chunk_size,
+                                 cache->start + cache->size - cur);
+                       ret = btrfs_alloc_data_chunk(trans, extent_root,
+                                       &cur_backup, len,
+                                       BTRFS_BLOCK_GROUP_DATA, 1);
+                       if (ret < 0)
+                               break;
+                       ret = btrfs_make_block_group(trans, extent_root, 0,
+                                       BTRFS_BLOCK_GROUP_DATA,
+                                       BTRFS_FIRST_CHUNK_TREE_OBJECTID,
+                                       cur, len);
+                       if (ret < 0)
+                               break;
+                       cur += len;
                }
        }
-       memset(&dst->reserved, 0, sizeof(dst->reserved));
+       return ret;
 }
 
 /*
- * copy a single inode. do all the required works, such as cloning
- * inode item, creating file extents and creating directory entries.
+ * Init the temp btrfs to a operational status.
+ *
+ * It will fix the extent usage accounting(XXX: Do we really need?) and
+ * insert needed data chunks, to ensure all old fs data extents are covered
+ * by DATA chunks, preventing wrong chunks are allocated.
+ *
+ * And also create convert image subvolume and relocation tree.
+ * (XXX: Not need again?)
+ * But the convert image subvolume is *NOT* linked to fs tree yet.
  */
-static int ext2_copy_single_inode(struct btrfs_trans_handle *trans,
-                            struct btrfs_root *root, u64 objectid,
-                            ext2_filsys ext2_fs, ext2_ino_t ext2_ino,
-                            struct ext2_inode *ext2_inode,
-                            int datacsum, int packing, int noxattr)
+static int init_btrfs(struct btrfs_mkfs_config *cfg, struct btrfs_root *root,
+                        struct btrfs_convert_context *cctx, int datacsum,
+                        int packing, int noxattr)
 {
+       struct btrfs_key location;
+       struct btrfs_trans_handle *trans;
+       struct btrfs_fs_info *fs_info = root->fs_info;
        int ret;
-       struct btrfs_inode_item btrfs_inode;
-
-       if (ext2_inode->i_links_count == 0)
-               return 0;
 
-       ext2_copy_inode_item(&btrfs_inode, ext2_inode, ext2_fs->blocksize);
-       if (!datacsum && S_ISREG(ext2_inode->i_mode)) {
-               u32 flags = btrfs_stack_inode_flags(&btrfs_inode) |
-                           BTRFS_INODE_NODATASUM;
-               btrfs_set_stack_inode_flags(&btrfs_inode, flags);
-       }
-
-       switch (ext2_inode->i_mode & S_IFMT) {
-       case S_IFREG:
-               ret = ext2_create_file_extents(trans, root, objectid,
-                       &btrfs_inode, ext2_fs, ext2_ino, datacsum, packing);
-               break;
-       case S_IFDIR:
-               ret = ext2_create_dir_entries(trans, root, objectid,
-                               &btrfs_inode, ext2_fs, ext2_ino);
-               break;
-       case S_IFLNK:
-               ret = ext2_create_symbol_link(trans, root, objectid,
-                               &btrfs_inode, ext2_fs, ext2_ino, ext2_inode);
-               break;
-       default:
-               ret = 0;
-               break;
+       /*
+        * Don't alloc any metadata/system chunk, as we don't want
+        * any meta/sys chunk allcated before all data chunks are inserted.
+        * Or we screw up the chunk layout just like the old implement.
+        */
+       fs_info->avoid_sys_chunk_alloc = 1;
+       fs_info->avoid_meta_chunk_alloc = 1;
+       trans = btrfs_start_transaction(root, 1);
+       if (!trans) {
+               error("unable to start transaction");
+               ret = -EINVAL;
+               goto err;
        }
+       ret = btrfs_fix_block_accounting(trans, root);
        if (ret)
-               return ret;
-
-       if (!noxattr) {
-               ret = ext2_copy_extended_attrs(trans, root, objectid,
-                               &btrfs_inode, ext2_fs, ext2_ino);
-               if (ret)
-                       return ret;
-       }
-       return btrfs_insert_inode(trans, root, objectid, &btrfs_inode);
-}
-
-/*
- * scan ext2's inode bitmap and copy all used inodes.
- */
-static int ext2_copy_inodes(struct btrfs_convert_context *cctx,
-                           struct btrfs_root *root,
-                           int datacsum, int packing, int noxattr, struct task_ctx *p)
-{
-       ext2_filsys ext2_fs = cctx->fs_data;
-       int ret;
-       errcode_t err;
-       ext2_inode_scan ext2_scan;
-       struct ext2_inode ext2_inode;
-       ext2_ino_t ext2_ino;
-       u64 objectid;
-       struct btrfs_trans_handle *trans;
+               goto err;
+       ret = make_convert_data_block_groups(trans, fs_info, cfg, cctx);
+       if (ret)
+               goto err;
+       ret = btrfs_make_root_dir(trans, fs_info->tree_root,
+                                 BTRFS_ROOT_TREE_DIR_OBJECTID);
+       if (ret)
+               goto err;
+       memcpy(&location, &root->root_key, sizeof(location));
+       location.offset = (u64)-1;
+       ret = btrfs_insert_dir_item(trans, fs_info->tree_root, "default", 7,
+                               btrfs_super_root_dir(fs_info->super_copy),
+                               &location, BTRFS_FT_DIR, 0);
+       if (ret)
+               goto err;
+       ret = btrfs_insert_inode_ref(trans, fs_info->tree_root, "default", 7,
+                               location.objectid,
+                               btrfs_super_root_dir(fs_info->super_copy), 0);
+       if (ret)
+               goto err;
+       btrfs_set_root_dirid(&fs_info->fs_root->root_item,
+                            BTRFS_FIRST_FREE_OBJECTID);
 
-       trans = btrfs_start_transaction(root, 1);
-       if (!trans)
-               return -ENOMEM;
-       err = ext2fs_open_inode_scan(ext2_fs, 0, &ext2_scan);
-       if (err) {
-               fprintf(stderr, "ext2fs_open_inode_scan: %s\n", error_message(err));
-               return -1;
-       }
-       while (!(err = ext2fs_get_next_inode(ext2_scan, &ext2_ino,
-                                            &ext2_inode))) {
-               /* no more inodes */
-               if (ext2_ino == 0)
-                       break;
-               /* skip special inode in ext2fs */
-               if (ext2_ino < EXT2_GOOD_OLD_FIRST_INO &&
-                   ext2_ino != EXT2_ROOT_INO)
-                       continue;
-               objectid = ext2_ino + INO_OFFSET;
-               ret = ext2_copy_single_inode(trans, root,
-                                       objectid, ext2_fs, ext2_ino,
-                                       &ext2_inode, datacsum, packing,
-                                       noxattr);
-               p->cur_copy_inodes++;
-               if (ret)
-                       return ret;
-               if (trans->blocks_used >= 4096) {
-                       ret = btrfs_commit_transaction(trans, root);
-                       BUG_ON(ret);
-                       trans = btrfs_start_transaction(root, 1);
-                       BUG_ON(!trans);
-               }
+       /* subvol for fs image file */
+       ret = create_subvol(trans, root, CONV_IMAGE_SUBVOL_OBJECTID);
+       if (ret < 0) {
+               error("failed to create subvolume image root: %d", ret);
+               goto err;
        }
-       if (err) {
-               fprintf(stderr, "ext2fs_get_next_inode: %s\n", error_message(err));
-               return -1;
+       /* subvol for data relocation tree */
+       ret = create_subvol(trans, root, BTRFS_DATA_RELOC_TREE_OBJECTID);
+       if (ret < 0) {
+               error("failed to create DATA_RELOC root: %d", ret);
+               goto err;
        }
-       ret = btrfs_commit_transaction(trans, root);
-       BUG_ON(ret);
-       ext2fs_close_inode_scan(ext2_scan);
 
+       ret = btrfs_commit_transaction(trans, root);
+       fs_info->avoid_sys_chunk_alloc = 0;
+       fs_info->avoid_meta_chunk_alloc = 0;
+err:
        return ret;
 }
 
 /*
- * Relocate old fs data in one reserved ranges
- *
- * Since all old fs data in reserved range is not covered by any chunk nor
- * data extent, we don't need to handle any reference but add new
- * extent/reference, which makes codes more clear
+ * Migrate super block to its default position and zero 0 ~ 16k
  */
-static int migrate_one_reserved_range(struct btrfs_trans_handle *trans,
-                                     struct btrfs_root *root,
-                                     struct cache_tree *used,
-                                     struct btrfs_inode_item *inode, int fd,
-                                     u64 ino, u64 start, u64 len, int datacsum)
+static int migrate_super_block(int fd, u64 old_bytenr, u32 sectorsize)
 {
-       u64 cur_off = start;
-       u64 cur_len = len;
-       u64 hole_start = start;
-       u64 hole_len;
-       struct cache_extent *cache;
-       struct btrfs_key key;
-       struct extent_buffer *eb;
-       int ret = 0;
+       int ret;
+       struct extent_buffer *buf;
+       struct btrfs_super_block *super;
+       u32 len;
+       u32 bytenr;
 
-       while (cur_off < start + len) {
-               cache = lookup_cache_extent(used, cur_off, cur_len);
-               if (!cache)
-                       break;
-               cur_off = max(cache->start, cur_off);
-               cur_len = min(cache->start + cache->size, start + len) -
-                         cur_off;
-               BUG_ON(cur_len < root->sectorsize);
+       buf = malloc(sizeof(*buf) + sectorsize);
+       if (!buf)
+               return -ENOMEM;
 
-               /* reserve extent for the data */
-               ret = btrfs_reserve_extent(trans, root, cur_len, 0, 0, (u64)-1,
-                                          &key, 1);
-               if (ret < 0)
-                       break;
+       buf->len = sectorsize;
+       ret = pread(fd, buf->data, sectorsize, old_bytenr);
+       if (ret != sectorsize)
+               goto fail;
 
-               eb = malloc(sizeof(*eb) + cur_len);
-               if (!eb) {
-                       ret = -ENOMEM;
-                       break;
-               }
+       super = (struct btrfs_super_block *)buf->data;
+       BUG_ON(btrfs_super_bytenr(super) != old_bytenr);
+       btrfs_set_super_bytenr(super, BTRFS_SUPER_INFO_OFFSET);
 
-               ret = pread(fd, eb->data, cur_len, cur_off);
-               if (ret < cur_len) {
-                       ret = (ret < 0 ? ret : -EIO);
-                       free(eb);
-                       break;
-               }
-               eb->start = key.objectid;
-               eb->len = key.offset;
+       csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
+       ret = pwrite(fd, buf->data, sectorsize, BTRFS_SUPER_INFO_OFFSET);
+       if (ret != sectorsize)
+               goto fail;
 
-               /* Write the data */
-               ret = write_and_map_eb(trans, root, eb);
-               free(eb);
-               if (ret < 0)
-                       break;
+       ret = fsync(fd);
+       if (ret)
+               goto fail;
 
-               /* Now handle extent item and file extent things */
-               ret = btrfs_record_file_extent(trans, root, ino, inode, cur_off,
-                                              key.objectid, key.offset);
-               if (ret < 0)
+       memset(buf->data, 0, sectorsize);
+       for (bytenr = 0; bytenr < BTRFS_SUPER_INFO_OFFSET; ) {
+               len = BTRFS_SUPER_INFO_OFFSET - bytenr;
+               if (len > sectorsize)
+                       len = sectorsize;
+               ret = pwrite(fd, buf->data, len, bytenr);
+               if (ret != len) {
+                       fprintf(stderr, "unable to zero fill device\n");
                        break;
-               /* Finally, insert csum items */
-               if (datacsum)
-                       ret = csum_disk_extent(trans, root, key.objectid,
-                                              key.offset);
-
-               /* Don't forget to insert hole */
-               hole_len = cur_off - hole_start;
-               if (hole_len) {
-                       ret = btrfs_record_file_extent(trans, root, ino, inode,
-                                       hole_start, 0, hole_len);
-                       if (ret < 0)
-                               break;
                }
-
-               cur_off += key.offset;
-               hole_start = cur_off;
-               cur_len = start + len - cur_off;
+               bytenr += len;
        }
-       /* Last hole */
-       if (start + len - hole_start > 0)
-               ret = btrfs_record_file_extent(trans, root, ino, inode,
-                               hole_start, 0, start + len - hole_start);
+       ret = 0;
+       fsync(fd);
+fail:
+       free(buf);
+       if (ret > 0)
+               ret = -1;
        return ret;
 }
 
-/*
- * Relocate the used ext2 data in reserved ranges
- * [0,1M)
- * [btrfs_sb_offset(1), +BTRFS_STRIPE_LEN)
- * [btrfs_sb_offset(2), +BTRFS_STRIPE_LEN)
- */
-static int migrate_reserved_ranges(struct btrfs_trans_handle *trans,
-                                  struct btrfs_root *root,
-                                  struct cache_tree *used,
-                                  struct btrfs_inode_item *inode, int fd,
-                                  u64 ino, u64 total_bytes, int datacsum)
+static int prepare_system_chunk_sb(struct btrfs_super_block *super)
 {
-       u64 cur_off;
-       u64 cur_len;
-       int ret = 0;
+       struct btrfs_chunk *chunk;
+       struct btrfs_disk_key *key;
+       u32 sectorsize = btrfs_super_sectorsize(super);
 
-       /* 0 ~ 1M */
-       cur_off = 0;
-       cur_len = 1024 * 1024;
-       ret = migrate_one_reserved_range(trans, root, used, inode, fd, ino,
-                                        cur_off, cur_len, datacsum);
-       if (ret < 0)
-               return ret;
+       key = (struct btrfs_disk_key *)(super->sys_chunk_array);
+       chunk = (struct btrfs_chunk *)(super->sys_chunk_array +
+                                      sizeof(struct btrfs_disk_key));
 
-       /* second sb(fisrt sb is included in 0~1M) */
-       cur_off = btrfs_sb_offset(1);
-       cur_len = min(total_bytes, cur_off + BTRFS_STRIPE_LEN) - cur_off;
-       if (cur_off > total_bytes)
-               return ret;
-       ret = migrate_one_reserved_range(trans, root, used, inode, fd, ino,
-                                        cur_off, cur_len, datacsum);
-       if (ret < 0)
-               return ret;
+       btrfs_set_disk_key_objectid(key, BTRFS_FIRST_CHUNK_TREE_OBJECTID);
+       btrfs_set_disk_key_type(key, BTRFS_CHUNK_ITEM_KEY);
+       btrfs_set_disk_key_offset(key, 0);
 
-       /* Last sb */
-       cur_off = btrfs_sb_offset(2);
-       cur_len = min(total_bytes, cur_off + BTRFS_STRIPE_LEN) - cur_off;
-       if (cur_off > total_bytes)
-               return ret;
-       ret = migrate_one_reserved_range(trans, root, used, inode, fd, ino,
-                                        cur_off, cur_len, datacsum);
-       return ret;
+       btrfs_set_stack_chunk_length(chunk, btrfs_super_total_bytes(super));
+       btrfs_set_stack_chunk_owner(chunk, BTRFS_EXTENT_TREE_OBJECTID);
+       btrfs_set_stack_chunk_stripe_len(chunk, BTRFS_STRIPE_LEN);
+       btrfs_set_stack_chunk_type(chunk, BTRFS_BLOCK_GROUP_SYSTEM);
+       btrfs_set_stack_chunk_io_align(chunk, sectorsize);
+       btrfs_set_stack_chunk_io_width(chunk, sectorsize);
+       btrfs_set_stack_chunk_sector_size(chunk, sectorsize);
+       btrfs_set_stack_chunk_num_stripes(chunk, 1);
+       btrfs_set_stack_chunk_sub_stripes(chunk, 0);
+       chunk->stripe.devid = super->dev_item.devid;
+       btrfs_set_stack_stripe_offset(&chunk->stripe, 0);
+       memcpy(chunk->stripe.dev_uuid, super->dev_item.uuid, BTRFS_UUID_SIZE);
+       btrfs_set_super_sys_array_size(super, sizeof(*key) + sizeof(*chunk));
+       return 0;
 }
 
-static int wipe_reserved_ranges(struct cache_tree *tree, u64 min_stripe_size,
-                               int ensure_size);
+#if BTRFSCONVERT_EXT2
 
 /*
- * Create the fs image file of old filesystem.
- *
- * This is completely fs independent as we have cctx->used, only
- * need to create file extents pointing to all the positions.
+ * Open Ext2fs in readonly mode, read block allocation bitmap and
+ * inode bitmap into memory.
  */
-static int create_image(struct btrfs_root *root,
-                          struct btrfs_mkfs_config *cfg,
-                          struct btrfs_convert_context *cctx, int fd,
-                          u64 size, char *name, int datacsum)
+static int ext2_open_fs(struct btrfs_convert_context *cctx, const char *name)
 {
-       struct btrfs_inode_item buf;
-       struct btrfs_trans_handle *trans;
-       struct btrfs_path *path = NULL;
-       struct btrfs_key key;
-       struct cache_extent *cache;
-       struct cache_tree used_tmp;
-       u64 cur;
-       u64 ino;
-       u64 flags = BTRFS_INODE_READONLY;
-       int ret;
-
-       if (!datacsum)
-               flags |= BTRFS_INODE_NODATASUM;
-
-       trans = btrfs_start_transaction(root, 1);
-       if (!trans)
-               return -ENOMEM;
-
-       cache_tree_init(&used_tmp);
-
-       ret = btrfs_find_free_objectid(trans, root, BTRFS_FIRST_FREE_OBJECTID,
-                                      &ino);
-       if (ret < 0)
-               goto out;
-       ret = btrfs_new_inode(trans, root, ino, 0400 | S_IFREG);
-       if (ret < 0)
-               goto out;
-       ret = btrfs_change_inode_flags(trans, root, ino, flags);
-       if (ret < 0)
-               goto out;
-       ret = btrfs_add_link(trans, root, ino, BTRFS_FIRST_FREE_OBJECTID, name,
-                            strlen(name), BTRFS_FT_REG_FILE, NULL, 1);
-       if (ret < 0)
-               goto out;
-
-       path = btrfs_alloc_path();
-       if (!path) {
-               ret = -ENOMEM;
-               goto out;
-       }
-       key.objectid = ino;
-       key.type = BTRFS_INODE_ITEM_KEY;
-       key.offset = 0;
+       errcode_t ret;
+       ext2_filsys ext2_fs;
+       ext2_ino_t ino;
+       u32 ro_feature;
 
-       ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
+       ret = ext2fs_open(name, 0, 0, 0, unix_io_manager, &ext2_fs);
        if (ret) {
-               ret = (ret > 0 ? -ENOENT : ret);
-               goto out;
+               fprintf(stderr, "ext2fs_open: %s\n", error_message(ret));
+               return -1;
        }
-       read_extent_buffer(path->nodes[0], &buf,
-                       btrfs_item_ptr_offset(path->nodes[0], path->slots[0]),
-                       sizeof(buf));
-       btrfs_release_path(path);
-
        /*
-        * Create a new used space cache, which doesn't contain the reserved
-        * range
+        * We need to know exactly the used space, some RO compat flags like
+        * BIGALLOC will affect how used space is present.
+        * So we need manuall check any unsupported RO compat flags
         */
-       for (cache = first_cache_extent(&cctx->used); cache;
-            cache = next_cache_extent(cache)) {
-               ret = add_cache_extent(&used_tmp, cache->start, cache->size);
-               if (ret < 0)
-                       goto out;
+       ro_feature = ext2_fs->super->s_feature_ro_compat;
+       if (ro_feature & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP) {
+               error(
+"unsupported RO features detected: %x, abort convert to avoid possible corruption",
+                     ro_feature & ~EXT2_LIB_FEATURE_COMPAT_SUPP);
+               goto fail;
+       }
+       ret = ext2fs_read_inode_bitmap(ext2_fs);
+       if (ret) {
+               fprintf(stderr, "ext2fs_read_inode_bitmap: %s\n",
+                       error_message(ret));
+               goto fail;
+       }
+       ret = ext2fs_read_block_bitmap(ext2_fs);
+       if (ret) {
+               fprintf(stderr, "ext2fs_read_block_bitmap: %s\n",
+                       error_message(ret));
+               goto fail;
        }
-       ret = wipe_reserved_ranges(&used_tmp, 0, 0);
-       if (ret < 0)
-               goto out;
-
        /*
-        * Start from 1M, as 0~1M is reserved, and create_image_file_range()
-        * can't handle bytenr 0(will consider it as a hole)
+        * search each block group for a free inode. this set up
+        * uninit block/inode bitmaps appropriately.
         */
-       cur = 1024 * 1024;
-       while (cur < size) {
-               u64 len = size - cur;
-
-               ret = create_image_file_range(trans, root, &used_tmp,
-                                               &buf, ino, cur, &len, datacsum);
-               if (ret < 0)
-                       goto out;
-               cur += len;
+       ino = 1;
+       while (ino <= ext2_fs->super->s_inodes_count) {
+               ext2_ino_t foo;
+               ext2fs_new_inode(ext2_fs, ino, 0, NULL, &foo);
+               ino += EXT2_INODES_PER_GROUP(ext2_fs->super);
        }
-       /* Handle the reserved ranges */
-       ret = migrate_reserved_ranges(trans, root, &cctx->used, &buf, fd, ino,
-                                     cfg->num_bytes, datacsum);
-
 
-       key.objectid = ino;
-       key.type = BTRFS_INODE_ITEM_KEY;
-       key.offset = 0;
-       ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
-       if (ret) {
-               ret = (ret > 0 ? -ENOENT : ret);
-               goto out;
+       if (!(ext2_fs->super->s_feature_incompat &
+             EXT2_FEATURE_INCOMPAT_FILETYPE)) {
+               error("filetype feature is missing");
+               goto fail;
        }
-       btrfs_set_stack_inode_size(&buf, cfg->num_bytes);
-       write_extent_buffer(path->nodes[0], &buf,
-                       btrfs_item_ptr_offset(path->nodes[0], path->slots[0]),
-                       sizeof(buf));
-out:
-       free_extent_cache_tree(&used_tmp);
-       btrfs_free_path(path);
-       btrfs_commit_transaction(trans, root);
-       return ret;
+
+       cctx->fs_data = ext2_fs;
+       cctx->blocksize = ext2_fs->blocksize;
+       cctx->block_count = ext2_fs->super->s_blocks_count;
+       cctx->total_bytes = ext2_fs->blocksize * ext2_fs->super->s_blocks_count;
+       cctx->volume_name = strndup(ext2_fs->super->s_volume_name, 16);
+       cctx->first_data_block = ext2_fs->super->s_first_data_block;
+       cctx->inodes_count = ext2_fs->super->s_inodes_count;
+       cctx->free_inodes_count = ext2_fs->super->s_free_inodes_count;
+       return 0;
+fail:
+       ext2fs_close(ext2_fs);
+       return -1;
 }
 
-static struct btrfs_root * link_subvol(struct btrfs_root *root,
-               const char *base, u64 root_objectid)
+static int __ext2_add_one_block(ext2_filsys fs, char *bitmap,
+                               unsigned long group_nr, struct cache_tree *used)
 {
-       struct btrfs_trans_handle *trans;
-       struct btrfs_fs_info *fs_info = root->fs_info;
-       struct btrfs_root *tree_root = fs_info->tree_root;
-       struct btrfs_root *new_root = NULL;
-       struct btrfs_path *path;
-       struct btrfs_inode_item *inode_item;
-       struct extent_buffer *leaf;
-       struct btrfs_key key;
-       u64 dirid = btrfs_root_dirid(&root->root_item);
-       u64 index = 2;
-       char buf[BTRFS_NAME_LEN + 1]; /* for snprintf null */
-       int len;
-       int i;
-       int ret;
-
-       len = strlen(base);
-       if (len == 0 || len > BTRFS_NAME_LEN)
-               return NULL;
-
-       path = btrfs_alloc_path();
-       BUG_ON(!path);
-
-       key.objectid = dirid;
-       key.type = BTRFS_DIR_INDEX_KEY;
-       key.offset = (u64)-1;
+       unsigned long offset;
+       unsigned i;
+       int ret = 0;
 
-       ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
-       BUG_ON(ret <= 0);
+       offset = fs->super->s_first_data_block;
+       offset /= EXT2FS_CLUSTER_RATIO(fs);
+       offset += group_nr * EXT2_CLUSTERS_PER_GROUP(fs->super);
+       for (i = 0; i < EXT2_CLUSTERS_PER_GROUP(fs->super); i++) {
+               if (ext2fs_test_bit(i, bitmap)) {
+                       u64 start;
 
-       if (path->slots[0] > 0) {
-               path->slots[0]--;
-               btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
-               if (key.objectid == dirid && key.type == BTRFS_DIR_INDEX_KEY)
-                       index = key.offset + 1;
+                       start = (i + offset) * EXT2FS_CLUSTER_RATIO(fs);
+                       start *= fs->blocksize;
+                       ret = add_merge_cache_extent(used, start,
+                                                    fs->blocksize);
+                       if (ret < 0)
+                               break;
+               }
        }
-       btrfs_release_path(path);
-
-       trans = btrfs_start_transaction(root, 1);
-       BUG_ON(!trans);
+       return ret;
+}
 
-       key.objectid = dirid;
-       key.offset = 0;
-       key.type =  BTRFS_INODE_ITEM_KEY;
+/*
+ * Read all used ext2 space into cctx->used cache tree
+ */
+static int ext2_read_used_space(struct btrfs_convert_context *cctx)
+{
+       ext2_filsys fs = (ext2_filsys)cctx->fs_data;
+       blk64_t blk_itr = EXT2FS_B2C(fs, fs->super->s_first_data_block);
+       struct cache_tree *used_tree = &cctx->used;
+       char *block_bitmap = NULL;
+       unsigned long i;
+       int block_nbytes;
+       int ret = 0;
 
-       ret = btrfs_lookup_inode(trans, root, path, &key, 1);
-       BUG_ON(ret);
-       leaf = path->nodes[0];
-       inode_item = btrfs_item_ptr(leaf, path->slots[0],
-                                   struct btrfs_inode_item);
+       block_nbytes = EXT2_CLUSTERS_PER_GROUP(fs->super) / 8;
+       /* Shouldn't happen */
+       BUG_ON(!fs->block_map);
 
-       key.objectid = root_objectid;
-       key.offset = (u64)-1;
-       key.type = BTRFS_ROOT_ITEM_KEY;
+       block_bitmap = malloc(block_nbytes);
+       if (!block_bitmap)
+               return -ENOMEM;
 
-       memcpy(buf, base, len);
-       for (i = 0; i < 1024; i++) {
-               ret = btrfs_insert_dir_item(trans, root, buf, len,
-                                           dirid, &key, BTRFS_FT_DIR, index);
-               if (ret != -EEXIST)
+       for (i = 0; i < fs->group_desc_count; i++) {
+               ret = ext2fs_get_block_bitmap_range(fs->block_map, blk_itr,
+                                               block_nbytes * 8, block_bitmap);
+               if (ret) {
+                       error("fail to get bitmap from ext2, %s",
+                             strerror(-ret));
                        break;
-               len = snprintf(buf, ARRAY_SIZE(buf), "%s%d", base, i);
-               if (len < 1 || len > BTRFS_NAME_LEN) {
-                       ret = -EINVAL;
+               }
+               ret = __ext2_add_one_block(fs, block_bitmap, i, used_tree);
+               if (ret < 0) {
+                       error("fail to build used space tree, %s",
+                             strerror(-ret));
                        break;
                }
+               blk_itr += EXT2_CLUSTERS_PER_GROUP(fs->super);
        }
-       if (ret)
-               goto fail;
-
-       btrfs_set_inode_size(leaf, inode_item, len * 2 +
-                            btrfs_inode_size(leaf, inode_item));
-       btrfs_mark_buffer_dirty(leaf);
-       btrfs_release_path(path);
 
-       /* add the backref first */
-       ret = btrfs_add_root_ref(trans, tree_root, root_objectid,
-                                BTRFS_ROOT_BACKREF_KEY,
-                                root->root_key.objectid,
-                                dirid, index, buf, len);
-       BUG_ON(ret);
+       free(block_bitmap);
+       return ret;
+}
 
-       /* now add the forward ref */
-       ret = btrfs_add_root_ref(trans, tree_root, root->root_key.objectid,
-                                BTRFS_ROOT_REF_KEY, root_objectid,
-                                dirid, index, buf, len);
+static void ext2_close_fs(struct btrfs_convert_context *cctx)
+{
+       if (cctx->volume_name) {
+               free(cctx->volume_name);
+               cctx->volume_name = NULL;
+       }
+       ext2fs_close(cctx->fs_data);
+}
 
-       ret = btrfs_commit_transaction(trans, root);
-       BUG_ON(ret);
+struct dir_iterate_data {
+       struct btrfs_trans_handle *trans;
+       struct btrfs_root *root;
+       struct btrfs_inode_item *inode;
+       u64 objectid;
+       u64 index_cnt;
+       u64 parent;
+       int errcode;
+};
 
-       new_root = btrfs_read_fs_root(fs_info, &key);
-       if (IS_ERR(new_root))
-               new_root = NULL;
-fail:
-       btrfs_free_path(path);
-       return new_root;
-}
+static u8 ext2_filetype_conversion_table[EXT2_FT_MAX] = {
+       [EXT2_FT_UNKNOWN]       = BTRFS_FT_UNKNOWN,
+       [EXT2_FT_REG_FILE]      = BTRFS_FT_REG_FILE,
+       [EXT2_FT_DIR]           = BTRFS_FT_DIR,
+       [EXT2_FT_CHRDEV]        = BTRFS_FT_CHRDEV,
+       [EXT2_FT_BLKDEV]        = BTRFS_FT_BLKDEV,
+       [EXT2_FT_FIFO]          = BTRFS_FT_FIFO,
+       [EXT2_FT_SOCK]          = BTRFS_FT_SOCK,
+       [EXT2_FT_SYMLINK]       = BTRFS_FT_SYMLINK,
+};
 
-static int create_subvol(struct btrfs_trans_handle *trans,
-                        struct btrfs_root *root, u64 root_objectid)
+static int ext2_dir_iterate_proc(ext2_ino_t dir, int entry,
+                           struct ext2_dir_entry *dirent,
+                           int offset, int blocksize,
+                           char *buf,void *priv_data)
 {
-       struct extent_buffer *tmp;
-       struct btrfs_root *new_root;
-       struct btrfs_key key;
-       struct btrfs_root_item root_item;
        int ret;
+       int file_type;
+       u64 objectid;
+       char dotdot[] = "..";
+       struct dir_iterate_data *idata = (struct dir_iterate_data *)priv_data;
+       int name_len;
 
-       ret = btrfs_copy_root(trans, root, root->node, &tmp,
-                             root_objectid);
-       BUG_ON(ret);
-
-       memcpy(&root_item, &root->root_item, sizeof(root_item));
-       btrfs_set_root_bytenr(&root_item, tmp->start);
-       btrfs_set_root_level(&root_item, btrfs_header_level(tmp));
-       btrfs_set_root_generation(&root_item, trans->transid);
-       free_extent_buffer(tmp);
+       name_len = dirent->name_len & 0xFF;
 
-       key.objectid = root_objectid;
-       key.type = BTRFS_ROOT_ITEM_KEY;
-       key.offset = trans->transid;
-       ret = btrfs_insert_root(trans, root->fs_info->tree_root,
-                               &key, &root_item);
+       objectid = dirent->inode + INO_OFFSET;
+       if (!strncmp(dirent->name, dotdot, name_len)) {
+               if (name_len == 2) {
+                       BUG_ON(idata->parent != 0);
+                       idata->parent = objectid;
+               }
+               return 0;
+       }
+       if (dirent->inode < EXT2_GOOD_OLD_FIRST_INO)
+               return 0;
 
-       key.offset = (u64)-1;
-       new_root = btrfs_read_fs_root(root->fs_info, &key);
-       BUG_ON(!new_root || IS_ERR(new_root));
+       file_type = dirent->name_len >> 8;
+       BUG_ON(file_type > EXT2_FT_SYMLINK);
 
-       ret = btrfs_make_root_dir(trans, new_root, BTRFS_FIRST_FREE_OBJECTID);
-       BUG_ON(ret);
+       ret = convert_insert_dirent(idata->trans, idata->root, dirent->name,
+                                   name_len, idata->objectid, objectid,
+                                   ext2_filetype_conversion_table[file_type],
+                                   idata->index_cnt, idata->inode);
+       if (ret < 0) {
+               idata->errcode = ret;
+               return BLOCK_ABORT;
+       }
 
+       idata->index_cnt++;
        return 0;
 }
 
-/*
- * New make_btrfs() has handle system and meta chunks quite well.
- * So only need to add remaining data chunks.
- */
-static int make_convert_data_block_groups(struct btrfs_trans_handle *trans,
-                                         struct btrfs_fs_info *fs_info,
-                                         struct btrfs_mkfs_config *cfg,
-                                         struct btrfs_convert_context *cctx)
+static int ext2_create_dir_entries(struct btrfs_trans_handle *trans,
+                             struct btrfs_root *root, u64 objectid,
+                             struct btrfs_inode_item *btrfs_inode,
+                             ext2_filsys ext2_fs, ext2_ino_t ext2_ino)
 {
-       struct btrfs_root *extent_root = fs_info->extent_root;
-       struct cache_tree *data_chunks = &cctx->data_chunks;
-       struct cache_extent *cache;
-       u64 max_chunk_size;
-       int ret = 0;
-
-       /*
-        * Don't create data chunk over 10% of the convert device
-        * And for single chunk, don't create chunk larger than 1G.
-        */
-       max_chunk_size = cfg->num_bytes / 10;
-       max_chunk_size = min((u64)(1024 * 1024 * 1024), max_chunk_size);
-       max_chunk_size = round_down(max_chunk_size, extent_root->sectorsize);
-
-       for (cache = first_cache_extent(data_chunks); cache;
-            cache = next_cache_extent(cache)) {
-               u64 cur = cache->start;
-
-               while (cur < cache->start + cache->size) {
-                       u64 len;
-                       u64 cur_backup = cur;
+       int ret;
+       errcode_t err;
+       struct dir_iterate_data data = {
+               .trans          = trans,
+               .root           = root,
+               .inode          = btrfs_inode,
+               .objectid       = objectid,
+               .index_cnt      = 2,
+               .parent         = 0,
+               .errcode        = 0,
+       };
 
-                       len = min(max_chunk_size,
-                                 cache->start + cache->size - cur);
-                       ret = btrfs_alloc_data_chunk(trans, extent_root,
-                                       &cur_backup, len,
-                                       BTRFS_BLOCK_GROUP_DATA, 1);
-                       if (ret < 0)
-                               break;
-                       ret = btrfs_make_block_group(trans, extent_root, 0,
-                                       BTRFS_BLOCK_GROUP_DATA,
-                                       BTRFS_FIRST_CHUNK_TREE_OBJECTID,
-                                       cur, len);
-                       if (ret < 0)
-                               break;
-                       cur += len;
-               }
+       err = ext2fs_dir_iterate2(ext2_fs, ext2_ino, 0, NULL,
+                                 ext2_dir_iterate_proc, &data);
+       if (err)
+               goto error;
+       ret = data.errcode;
+       if (ret == 0 && data.parent == objectid) {
+               ret = btrfs_insert_inode_ref(trans, root, "..", 2,
+                                            objectid, objectid, 0);
        }
        return ret;
+error:
+       fprintf(stderr, "ext2fs_dir_iterate2: %s\n", error_message(err));
+       return -1;
 }
 
-/*
- * Init the temp btrfs to a operational status.
- *
- * It will fix the extent usage accounting(XXX: Do we really need?) and
- * insert needed data chunks, to ensure all old fs data extents are covered
- * by DATA chunks, preventing wrong chunks are allocated.
- *
- * And also create convert image subvolume and relocation tree.
- * (XXX: Not need again?)
- * But the convert image subvolume is *NOT* linked to fs tree yet.
- */
-static int init_btrfs(struct btrfs_mkfs_config *cfg, struct btrfs_root *root,
-                        struct btrfs_convert_context *cctx, int datacsum,
-                        int packing, int noxattr)
+static int ext2_block_iterate_proc(ext2_filsys fs, blk_t *blocknr,
+                               e2_blkcnt_t blockcnt, blk_t ref_block,
+                               int ref_offset, void *priv_data)
 {
-       struct btrfs_key location;
-       struct btrfs_trans_handle *trans;
-       struct btrfs_fs_info *fs_info = root->fs_info;
        int ret;
-
-       /*
-        * Don't alloc any metadata/system chunk, as we don't want
-        * any meta/sys chunk allcated before all data chunks are inserted.
-        * Or we screw up the chunk layout just like the old implement.
-        */
-       fs_info->avoid_sys_chunk_alloc = 1;
-       fs_info->avoid_meta_chunk_alloc = 1;
-       trans = btrfs_start_transaction(root, 1);
-       BUG_ON(!trans);
-       ret = btrfs_fix_block_accounting(trans, root);
-       if (ret)
-               goto err;
-       ret = make_convert_data_block_groups(trans, fs_info, cfg, cctx);
-       if (ret)
-               goto err;
-       ret = btrfs_make_root_dir(trans, fs_info->tree_root,
-                                 BTRFS_ROOT_TREE_DIR_OBJECTID);
-       if (ret)
-               goto err;
-       memcpy(&location, &root->root_key, sizeof(location));
-       location.offset = (u64)-1;
-       ret = btrfs_insert_dir_item(trans, fs_info->tree_root, "default", 7,
-                               btrfs_super_root_dir(fs_info->super_copy),
-                               &location, BTRFS_FT_DIR, 0);
-       if (ret)
-               goto err;
-       ret = btrfs_insert_inode_ref(trans, fs_info->tree_root, "default", 7,
-                               location.objectid,
-                               btrfs_super_root_dir(fs_info->super_copy), 0);
-       if (ret)
-               goto err;
-       btrfs_set_root_dirid(&fs_info->fs_root->root_item,
-                            BTRFS_FIRST_FREE_OBJECTID);
-
-       /* subvol for fs image file */
-       ret = create_subvol(trans, root, CONV_IMAGE_SUBVOL_OBJECTID);
-       if (ret < 0)
-               goto err;
-       /* subvol for data relocation tree */
-       ret = create_subvol(trans, root, BTRFS_DATA_RELOC_TREE_OBJECTID);
-       if (ret < 0)
-               goto err;
-
-       ret = btrfs_commit_transaction(trans, root);
-       fs_info->avoid_sys_chunk_alloc = 0;
-       fs_info->avoid_meta_chunk_alloc = 0;
-err:
-       return ret;
+       struct blk_iterate_data *idata;
+       idata = (struct blk_iterate_data *)priv_data;
+       ret = block_iterate_proc(*blocknr, blockcnt, idata);
+       if (ret) {
+               idata->errcode = ret;
+               return BLOCK_ABORT;
+       }
+       return 0;
 }
 
 /*
- * Migrate super block to its default position and zero 0 ~ 16k
+ * traverse file's data blocks, record these data blocks as file extents.
  */
-static int migrate_super_block(int fd, u64 old_bytenr, u32 sectorsize)
+static int ext2_create_file_extents(struct btrfs_trans_handle *trans,
+                              struct btrfs_root *root, u64 objectid,
+                              struct btrfs_inode_item *btrfs_inode,
+                              ext2_filsys ext2_fs, ext2_ino_t ext2_ino,
+                              int datacsum, int packing)
 {
        int ret;
-       struct extent_buffer *buf;
-       struct btrfs_super_block *super;
-       u32 len;
-       u32 bytenr;
-
-       BUG_ON(sectorsize < sizeof(*super));
-       buf = malloc(sizeof(*buf) + sectorsize);
-       if (!buf)
-               return -ENOMEM;
-
-       buf->len = sectorsize;
-       ret = pread(fd, buf->data, sectorsize, old_bytenr);
-       if (ret != sectorsize)
-               goto fail;
-
-       super = (struct btrfs_super_block *)buf->data;
-       BUG_ON(btrfs_super_bytenr(super) != old_bytenr);
-       btrfs_set_super_bytenr(super, BTRFS_SUPER_INFO_OFFSET);
+       char *buffer = NULL;
+       errcode_t err;
+       u32 last_block;
+       u32 sectorsize = root->sectorsize;
+       u64 inode_size = btrfs_stack_inode_size(btrfs_inode);
+       struct blk_iterate_data data;
 
-       csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
-       ret = pwrite(fd, buf->data, sectorsize, BTRFS_SUPER_INFO_OFFSET);
-       if (ret != sectorsize)
-               goto fail;
+       init_blk_iterate_data(&data, trans, root, btrfs_inode, objectid,
+                             datacsum);
 
-       ret = fsync(fd);
+       err = ext2fs_block_iterate2(ext2_fs, ext2_ino, BLOCK_FLAG_DATA_ONLY,
+                                   NULL, ext2_block_iterate_proc, &data);
+       if (err)
+               goto error;
+       ret = data.errcode;
        if (ret)
                goto fail;
+       if (packing && data.first_block == 0 && data.num_blocks > 0 &&
+           inode_size <= BTRFS_MAX_INLINE_DATA_SIZE(root)) {
+               u64 num_bytes = data.num_blocks * sectorsize;
+               u64 disk_bytenr = data.disk_block * sectorsize;
+               u64 nbytes;
 
-       memset(buf->data, 0, sectorsize);
-       for (bytenr = 0; bytenr < BTRFS_SUPER_INFO_OFFSET; ) {
-               len = BTRFS_SUPER_INFO_OFFSET - bytenr;
-               if (len > sectorsize)
-                       len = sectorsize;
-               ret = pwrite(fd, buf->data, len, bytenr);
-               if (ret != len) {
-                       fprintf(stderr, "unable to zero fill device\n");
-                       break;
-               }
-               bytenr += len;
+               buffer = malloc(num_bytes);
+               if (!buffer)
+                       return -ENOMEM;
+               ret = read_disk_extent(root, disk_bytenr, num_bytes, buffer);
+               if (ret)
+                       goto fail;
+               if (num_bytes > inode_size)
+                       num_bytes = inode_size;
+               ret = btrfs_insert_inline_extent(trans, root, objectid,
+                                                0, buffer, num_bytes);
+               if (ret)
+                       goto fail;
+               nbytes = btrfs_stack_inode_nbytes(btrfs_inode) + num_bytes;
+               btrfs_set_stack_inode_nbytes(btrfs_inode, nbytes);
+       } else if (data.num_blocks > 0) {
+               ret = record_file_blocks(&data, data.first_block,
+                                        data.disk_block, data.num_blocks);
+               if (ret)
+                       goto fail;
+       }
+       data.first_block += data.num_blocks;
+       last_block = (inode_size + sectorsize - 1) / sectorsize;
+       if (last_block > data.first_block) {
+               ret = record_file_blocks(&data, data.first_block, 0,
+                                        last_block - data.first_block);
        }
-       ret = 0;
-       fsync(fd);
 fail:
-       free(buf);
-       if (ret > 0)
-               ret = -1;
+       free(buffer);
        return ret;
+error:
+       fprintf(stderr, "ext2fs_block_iterate2: %s\n", error_message(err));
+       return -1;
 }
 
-static int prepare_system_chunk_sb(struct btrfs_super_block *super)
+static int ext2_create_symbol_link(struct btrfs_trans_handle *trans,
+                             struct btrfs_root *root, u64 objectid,
+                             struct btrfs_inode_item *btrfs_inode,
+                             ext2_filsys ext2_fs, ext2_ino_t ext2_ino,
+                             struct ext2_inode *ext2_inode)
 {
-       struct btrfs_chunk *chunk;
-       struct btrfs_disk_key *key;
-       u32 sectorsize = btrfs_super_sectorsize(super);
+       int ret;
+       char *pathname;
+       u64 inode_size = btrfs_stack_inode_size(btrfs_inode);
+       if (ext2fs_inode_data_blocks(ext2_fs, ext2_inode)) {
+               btrfs_set_stack_inode_size(btrfs_inode, inode_size + 1);
+               ret = ext2_create_file_extents(trans, root, objectid,
+                               btrfs_inode, ext2_fs, ext2_ino, 1, 1);
+               btrfs_set_stack_inode_size(btrfs_inode, inode_size);
+               return ret;
+       }
 
-       key = (struct btrfs_disk_key *)(super->sys_chunk_array);
-       chunk = (struct btrfs_chunk *)(super->sys_chunk_array +
-                                      sizeof(struct btrfs_disk_key));
+       pathname = (char *)&(ext2_inode->i_block[0]);
+       BUG_ON(pathname[inode_size] != 0);
+       ret = btrfs_insert_inline_extent(trans, root, objectid, 0,
+                                        pathname, inode_size + 1);
+       btrfs_set_stack_inode_nbytes(btrfs_inode, inode_size + 1);
+       return ret;
+}
 
-       btrfs_set_disk_key_objectid(key, BTRFS_FIRST_CHUNK_TREE_OBJECTID);
-       btrfs_set_disk_key_type(key, BTRFS_CHUNK_ITEM_KEY);
-       btrfs_set_disk_key_offset(key, 0);
+/*
+ * Following xattr/acl related codes are based on codes in
+ * fs/ext3/xattr.c and fs/ext3/acl.c
+ */
+#define EXT2_XATTR_BHDR(ptr) ((struct ext2_ext_attr_header *)(ptr))
+#define EXT2_XATTR_BFIRST(ptr) \
+       ((struct ext2_ext_attr_entry *)(EXT2_XATTR_BHDR(ptr) + 1))
+#define EXT2_XATTR_IHDR(inode) \
+       ((struct ext2_ext_attr_header *) ((void *)(inode) + \
+               EXT2_GOOD_OLD_INODE_SIZE + (inode)->i_extra_isize))
+#define EXT2_XATTR_IFIRST(inode) \
+       ((struct ext2_ext_attr_entry *) ((void *)EXT2_XATTR_IHDR(inode) + \
+               sizeof(EXT2_XATTR_IHDR(inode)->h_magic)))
 
-       btrfs_set_stack_chunk_length(chunk, btrfs_super_total_bytes(super));
-       btrfs_set_stack_chunk_owner(chunk, BTRFS_EXTENT_TREE_OBJECTID);
-       btrfs_set_stack_chunk_stripe_len(chunk, BTRFS_STRIPE_LEN);
-       btrfs_set_stack_chunk_type(chunk, BTRFS_BLOCK_GROUP_SYSTEM);
-       btrfs_set_stack_chunk_io_align(chunk, sectorsize);
-       btrfs_set_stack_chunk_io_width(chunk, sectorsize);
-       btrfs_set_stack_chunk_sector_size(chunk, sectorsize);
-       btrfs_set_stack_chunk_num_stripes(chunk, 1);
-       btrfs_set_stack_chunk_sub_stripes(chunk, 0);
-       chunk->stripe.devid = super->dev_item.devid;
-       btrfs_set_stack_stripe_offset(&chunk->stripe, 0);
-       memcpy(chunk->stripe.dev_uuid, super->dev_item.uuid, BTRFS_UUID_SIZE);
-       btrfs_set_super_sys_array_size(super, sizeof(*key) + sizeof(*chunk));
+static int ext2_xattr_check_names(struct ext2_ext_attr_entry *entry,
+                                 const void *end)
+{
+       struct ext2_ext_attr_entry *next;
+
+       while (!EXT2_EXT_IS_LAST_ENTRY(entry)) {
+               next = EXT2_EXT_ATTR_NEXT(entry);
+               if ((void *)next >= end)
+                       return -EIO;
+               entry = next;
+       }
        return 0;
 }
 
-static const struct btrfs_convert_operations ext2_convert_ops = {
-       .name                   = "ext2",
-       .open_fs                = ext2_open_fs,
-       .read_used_space        = ext2_read_used_space,
-       .copy_inodes            = ext2_copy_inodes,
-       .close_fs               = ext2_close_fs,
-};
+static int ext2_xattr_check_block(const char *buf, size_t size)
+{
+       int error;
+       struct ext2_ext_attr_header *header = EXT2_XATTR_BHDR(buf);
 
-static const struct btrfs_convert_operations *convert_operations[] = {
-       &ext2_convert_ops,
-};
+       if (header->h_magic != EXT2_EXT_ATTR_MAGIC ||
+           header->h_blocks != 1)
+               return -EIO;
+       error = ext2_xattr_check_names(EXT2_XATTR_BFIRST(buf), buf + size);
+       return error;
+}
 
-static int convert_open_fs(const char *devname,
-                          struct btrfs_convert_context *cctx)
+static int ext2_xattr_check_entry(struct ext2_ext_attr_entry *entry,
+                                 size_t size)
 {
-       int i;
+       size_t value_size = entry->e_value_size;
 
-       memset(cctx, 0, sizeof(*cctx));
+       if (entry->e_value_block != 0 || value_size > size ||
+           entry->e_value_offs + value_size > size)
+               return -EIO;
+       return 0;
+}
 
-       for (i = 0; i < ARRAY_SIZE(convert_operations); i++) {
-               int ret = convert_operations[i]->open_fs(cctx, devname);
+#define EXT2_ACL_VERSION       0x0001
 
-               if (ret == 0) {
-                       cctx->convert_ops = convert_operations[i];
-                       return ret;
-               }
-       }
+/* 23.2.5 acl_tag_t values */
 
-       fprintf(stderr, "No file system found to convert.\n");
-       return -1;
-}
+#define ACL_UNDEFINED_TAG       (0x00)
+#define ACL_USER_OBJ            (0x01)
+#define ACL_USER                (0x02)
+#define ACL_GROUP_OBJ           (0x04)
+#define ACL_GROUP               (0x08)
+#define ACL_MASK                (0x10)
+#define ACL_OTHER               (0x20)
 
-/*
- * Helper for expand and merge extent_cache for wipe_one_reserved_range() to
- * handle wiping a range that exists in cache.
- */
-static int _expand_extent_cache(struct cache_tree *tree,
-                               struct cache_extent *entry,
-                               u64 min_stripe_size, int backward)
+/* 23.2.7 ACL qualifier constants */
+
+#define ACL_UNDEFINED_ID        ((id_t)-1)
+
+typedef struct {
+       __le16          e_tag;
+       __le16          e_perm;
+       __le32          e_id;
+} ext2_acl_entry;
+
+typedef struct {
+       __le16          e_tag;
+       __le16          e_perm;
+} ext2_acl_entry_short;
+
+typedef struct {
+       __le32          a_version;
+} ext2_acl_header;
+
+static inline int ext2_acl_count(size_t size)
 {
-       struct cache_extent *ce;
-       int diff;
+       ssize_t s;
+       size -= sizeof(ext2_acl_header);
+       s = size - 4 * sizeof(ext2_acl_entry_short);
+       if (s < 0) {
+               if (size % sizeof(ext2_acl_entry_short))
+                       return -1;
+               return size / sizeof(ext2_acl_entry_short);
+       } else {
+               if (s % sizeof(ext2_acl_entry))
+                       return -1;
+               return s / sizeof(ext2_acl_entry) + 4;
+       }
+}
 
-       if (entry->size >= min_stripe_size)
-               return 0;
-       diff = min_stripe_size - entry->size;
+#define ACL_EA_VERSION         0x0002
 
-       if (backward) {
-               ce = prev_cache_extent(entry);
-               if (!ce)
-                       goto expand_back;
-               if (ce->start + ce->size >= entry->start - diff) {
-                       /* Directly merge with previous extent */
-                       ce->size = entry->start + entry->size - ce->start;
-                       remove_cache_extent(tree, entry);
-                       free(entry);
-                       return 0;
-               }
-expand_back:
-               /* No overlap, normal extent */
-               if (entry->start < diff) {
-                       error("cannot find space for data chunk layout");
-                       return -ENOSPC;
+typedef struct {
+       __le16          e_tag;
+       __le16          e_perm;
+       __le32          e_id;
+} acl_ea_entry;
+
+typedef struct {
+       __le32          a_version;
+       acl_ea_entry    a_entries[0];
+} acl_ea_header;
+
+static inline size_t acl_ea_size(int count)
+{
+       return sizeof(acl_ea_header) + count * sizeof(acl_ea_entry);
+}
+
+static int ext2_acl_to_xattr(void *dst, const void *src,
+                            size_t dst_size, size_t src_size)
+{
+       int i, count;
+       const void *end = src + src_size;
+       acl_ea_header *ext_acl = (acl_ea_header *)dst;
+       acl_ea_entry *dst_entry = ext_acl->a_entries;
+       ext2_acl_entry *src_entry;
+
+       if (src_size < sizeof(ext2_acl_header))
+               goto fail;
+       if (((ext2_acl_header *)src)->a_version !=
+           cpu_to_le32(EXT2_ACL_VERSION))
+               goto fail;
+       src += sizeof(ext2_acl_header);
+       count = ext2_acl_count(src_size);
+       if (count <= 0)
+               goto fail;
+
+       BUG_ON(dst_size < acl_ea_size(count));
+       ext_acl->a_version = cpu_to_le32(ACL_EA_VERSION);
+       for (i = 0; i < count; i++, dst_entry++) {
+               src_entry = (ext2_acl_entry *)src;
+               if (src + sizeof(ext2_acl_entry_short) > end)
+                       goto fail;
+               dst_entry->e_tag = src_entry->e_tag;
+               dst_entry->e_perm = src_entry->e_perm;
+               switch (le16_to_cpu(src_entry->e_tag)) {
+               case ACL_USER_OBJ:
+               case ACL_GROUP_OBJ:
+               case ACL_MASK:
+               case ACL_OTHER:
+                       src += sizeof(ext2_acl_entry_short);
+                       dst_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
+                       break;
+               case ACL_USER:
+               case ACL_GROUP:
+                       src += sizeof(ext2_acl_entry);
+                       if (src > end)
+                               goto fail;
+                       dst_entry->e_id = src_entry->e_id;
+                       break;
+               default:
+                       goto fail;
                }
-               entry->start -= diff;
-               entry->size += diff;
-               return 0;
-       }
-       ce = next_cache_extent(entry);
-       if (!ce)
-               goto expand_after;
-       if (entry->start + entry->size + diff >= ce->start) {
-               /* Directly merge with next extent */
-               entry->size = ce->start + ce->size - entry->start;
-               remove_cache_extent(tree, ce);
-               free(ce);
-               return 0;
        }
-expand_after:
-       entry->size += diff;
+       if (src != end)
+               goto fail;
        return 0;
+fail:
+       return -EINVAL;
 }
 
-/*
- * Remove one reserve range from given cache tree
- * if min_stripe_size is non-zero, it will ensure for split case,
- * all its split cache extent is no smaller than @min_strip_size / 2.
- */
-static int wipe_one_reserved_range(struct cache_tree *tree,
-                                  u64 start, u64 len, u64 min_stripe_size,
-                                  int ensure_size)
-{
-       struct cache_extent *cache;
-       int ret;
+static char *xattr_prefix_table[] = {
+       [1] =   "user.",
+       [2] =   "system.posix_acl_access",
+       [3] =   "system.posix_acl_default",
+       [4] =   "trusted.",
+       [6] =   "security.",
+};
 
-       BUG_ON(ensure_size && min_stripe_size == 0);
-       /*
-        * The logical here is simplified to handle special cases only
-        * So we don't need to consider merge case for ensure_size
-        */
-       BUG_ON(min_stripe_size && (min_stripe_size < len * 2 ||
-              min_stripe_size / 2 < BTRFS_STRIPE_LEN));
+static int ext2_copy_single_xattr(struct btrfs_trans_handle *trans,
+                            struct btrfs_root *root, u64 objectid,
+                            struct ext2_ext_attr_entry *entry,
+                            const void *data, u32 datalen)
+{
+       int ret = 0;
+       int name_len;
+       int name_index;
+       void *databuf = NULL;
+       char namebuf[XATTR_NAME_MAX + 1];
 
-       /* Also, wipe range should already be aligned */
-       BUG_ON(start != round_down(start, BTRFS_STRIPE_LEN) ||
-              start + len != round_up(start + len, BTRFS_STRIPE_LEN));
+       name_index = entry->e_name_index;
+       if (name_index >= ARRAY_SIZE(xattr_prefix_table) ||
+           xattr_prefix_table[name_index] == NULL)
+               return -EOPNOTSUPP;
+       name_len = strlen(xattr_prefix_table[name_index]) +
+                  entry->e_name_len;
+       if (name_len >= sizeof(namebuf))
+               return -ERANGE;
 
-       min_stripe_size /= 2;
+       if (name_index == 2 || name_index == 3) {
+               size_t bufsize = acl_ea_size(ext2_acl_count(datalen));
+               databuf = malloc(bufsize);
+               if (!databuf)
+                      return -ENOMEM;
+               ret = ext2_acl_to_xattr(databuf, data, bufsize, datalen);
+               if (ret)
+                       goto out;
+               data = databuf;
+               datalen = bufsize;
+       }
+       strncpy(namebuf, xattr_prefix_table[name_index], XATTR_NAME_MAX);
+       strncat(namebuf, EXT2_EXT_ATTR_NAME(entry), entry->e_name_len);
+       if (name_len + datalen > BTRFS_LEAF_DATA_SIZE(root) -
+           sizeof(struct btrfs_item) - sizeof(struct btrfs_dir_item)) {
+               fprintf(stderr, "skip large xattr on inode %Lu name %.*s\n",
+                       objectid - INO_OFFSET, name_len, namebuf);
+               goto out;
+       }
+       ret = btrfs_insert_xattr_item(trans, root, namebuf, name_len,
+                                     data, datalen, objectid);
+out:
+       free(databuf);
+       return ret;
+}
 
-       cache = lookup_cache_extent(tree, start, len);
-       if (!cache)
-               return 0;
+static int ext2_copy_extended_attrs(struct btrfs_trans_handle *trans,
+                              struct btrfs_root *root, u64 objectid,
+                              struct btrfs_inode_item *btrfs_inode,
+                              ext2_filsys ext2_fs, ext2_ino_t ext2_ino)
+{
+       int ret = 0;
+       int inline_ea = 0;
+       errcode_t err;
+       u32 datalen;
+       u32 block_size = ext2_fs->blocksize;
+       u32 inode_size = EXT2_INODE_SIZE(ext2_fs->super);
+       struct ext2_inode_large *ext2_inode;
+       struct ext2_ext_attr_entry *entry;
+       void *data;
+       char *buffer = NULL;
+       char inode_buf[EXT2_GOOD_OLD_INODE_SIZE];
 
-       if (start <= cache->start) {
-               /*
-                *      |--------cache---------|
-                * |-wipe-|
-                */
-               BUG_ON(start + len <= cache->start);
+       if (inode_size <= EXT2_GOOD_OLD_INODE_SIZE) {
+               ext2_inode = (struct ext2_inode_large *)inode_buf;
+       } else {
+               ext2_inode = (struct ext2_inode_large *)malloc(inode_size);
+               if (!ext2_inode)
+                      return -ENOMEM;
+       }
+       err = ext2fs_read_inode_full(ext2_fs, ext2_ino, (void *)ext2_inode,
+                                    inode_size);
+       if (err) {
+               fprintf(stderr, "ext2fs_read_inode_full: %s\n",
+                       error_message(err));
+               ret = -1;
+               goto out;
+       }
 
-               /*
-                * The wipe size is smaller than min_stripe_size / 2,
-                * so the result length should still meet min_stripe_size
-                * And no need to do alignment
-                */
-               cache->size -= (start + len - cache->start);
-               if (cache->size == 0) {
-                       remove_cache_extent(tree, cache);
-                       free(cache);
-                       return 0;
+       if (ext2_ino > ext2_fs->super->s_first_ino &&
+           inode_size > EXT2_GOOD_OLD_INODE_SIZE) {
+               if (EXT2_GOOD_OLD_INODE_SIZE +
+                   ext2_inode->i_extra_isize > inode_size) {
+                       ret = -EIO;
+                       goto out;
+               }
+               if (ext2_inode->i_extra_isize != 0 &&
+                   EXT2_XATTR_IHDR(ext2_inode)->h_magic ==
+                   EXT2_EXT_ATTR_MAGIC) {
+                       inline_ea = 1;
+               }
+       }
+       if (inline_ea) {
+               int total;
+               void *end = (void *)ext2_inode + inode_size;
+               entry = EXT2_XATTR_IFIRST(ext2_inode);
+               total = end - (void *)entry;
+               ret = ext2_xattr_check_names(entry, end);
+               if (ret)
+                       goto out;
+               while (!EXT2_EXT_IS_LAST_ENTRY(entry)) {
+                       ret = ext2_xattr_check_entry(entry, total);
+                       if (ret)
+                               goto out;
+                       data = (void *)EXT2_XATTR_IFIRST(ext2_inode) +
+                               entry->e_value_offs;
+                       datalen = entry->e_value_size;
+                       ret = ext2_copy_single_xattr(trans, root, objectid,
+                                               entry, data, datalen);
+                       if (ret)
+                               goto out;
+                       entry = EXT2_EXT_ATTR_NEXT(entry);
                }
+       }
 
-               BUG_ON(ensure_size && cache->size < min_stripe_size);
+       if (ext2_inode->i_file_acl == 0)
+               goto out;
 
-               cache->start = start + len;
-               return 0;
-       } else if (start > cache->start && start + len < cache->start +
-                  cache->size) {
-               /*
-                * |-------cache-----|
-                *      |-wipe-|
-                */
-               u64 old_start = cache->start;
-               u64 old_len = cache->size;
-               u64 insert_start = start + len;
-               u64 insert_len;
+       buffer = malloc(block_size);
+       if (!buffer) {
+               ret = -ENOMEM;
+               goto out;
+       }
+       err = ext2fs_read_ext_attr(ext2_fs, ext2_inode->i_file_acl, buffer);
+       if (err) {
+               fprintf(stderr, "ext2fs_read_ext_attr: %s\n",
+                       error_message(err));
+               ret = -1;
+               goto out;
+       }
+       ret = ext2_xattr_check_block(buffer, block_size);
+       if (ret)
+               goto out;
 
-               cache->size = start - cache->start;
-               /* Expand the leading half part if needed */
-               if (ensure_size && cache->size < min_stripe_size) {
-                       ret = _expand_extent_cache(tree, cache,
-                                       min_stripe_size, 1);
-                       if (ret < 0)
-                               return ret;
-               }
+       entry = EXT2_XATTR_BFIRST(buffer);
+       while (!EXT2_EXT_IS_LAST_ENTRY(entry)) {
+               ret = ext2_xattr_check_entry(entry, block_size);
+               if (ret)
+                       goto out;
+               data = buffer + entry->e_value_offs;
+               datalen = entry->e_value_size;
+               ret = ext2_copy_single_xattr(trans, root, objectid,
+                                       entry, data, datalen);
+               if (ret)
+                       goto out;
+               entry = EXT2_EXT_ATTR_NEXT(entry);
+       }
+out:
+       free(buffer);
+       if ((void *)ext2_inode != inode_buf)
+               free(ext2_inode);
+       return ret;
+}
+#define MINORBITS      20
+#define MKDEV(ma, mi)  (((ma) << MINORBITS) | (mi))
 
-               /* And insert the new one */
-               insert_len = old_start + old_len - start - len;
-               ret = add_merge_cache_extent(tree, insert_start, insert_len);
-               if (ret < 0)
-                       return ret;
+static inline dev_t old_decode_dev(u16 val)
+{
+       return MKDEV((val >> 8) & 255, val & 255);
+}
 
-               /* Expand the last half part if needed */
-               if (ensure_size && insert_len < min_stripe_size) {
-                       cache = lookup_cache_extent(tree, insert_start,
-                                                   insert_len);
-                       if (!cache || cache->start != insert_start ||
-                           cache->size != insert_len)
-                               return -ENOENT;
-                       ret = _expand_extent_cache(tree, cache,
-                                       min_stripe_size, 0);
-               }
+static inline dev_t new_decode_dev(u32 dev)
+{
+       unsigned major = (dev & 0xfff00) >> 8;
+       unsigned minor = (dev & 0xff) | ((dev >> 12) & 0xfff00);
+       return MKDEV(major, minor);
+}
 
-               return ret;
+static void ext2_copy_inode_item(struct btrfs_inode_item *dst,
+                          struct ext2_inode *src, u32 blocksize)
+{
+       btrfs_set_stack_inode_generation(dst, 1);
+       btrfs_set_stack_inode_sequence(dst, 0);
+       btrfs_set_stack_inode_transid(dst, 1);
+       btrfs_set_stack_inode_size(dst, src->i_size);
+       btrfs_set_stack_inode_nbytes(dst, 0);
+       btrfs_set_stack_inode_block_group(dst, 0);
+       btrfs_set_stack_inode_nlink(dst, src->i_links_count);
+       btrfs_set_stack_inode_uid(dst, src->i_uid | (src->i_uid_high << 16));
+       btrfs_set_stack_inode_gid(dst, src->i_gid | (src->i_gid_high << 16));
+       btrfs_set_stack_inode_mode(dst, src->i_mode);
+       btrfs_set_stack_inode_rdev(dst, 0);
+       btrfs_set_stack_inode_flags(dst, 0);
+       btrfs_set_stack_timespec_sec(&dst->atime, src->i_atime);
+       btrfs_set_stack_timespec_nsec(&dst->atime, 0);
+       btrfs_set_stack_timespec_sec(&dst->ctime, src->i_ctime);
+       btrfs_set_stack_timespec_nsec(&dst->ctime, 0);
+       btrfs_set_stack_timespec_sec(&dst->mtime, src->i_mtime);
+       btrfs_set_stack_timespec_nsec(&dst->mtime, 0);
+       btrfs_set_stack_timespec_sec(&dst->otime, 0);
+       btrfs_set_stack_timespec_nsec(&dst->otime, 0);
+
+       if (S_ISDIR(src->i_mode)) {
+               btrfs_set_stack_inode_size(dst, 0);
+               btrfs_set_stack_inode_nlink(dst, 1);
        }
-       /*
-        * |----cache-----|
-        *              |--wipe-|
-        * Wipe len should be small enough and no need to expand the
-        * remaining extent
-        */
-       cache->size = start - cache->start;
-       BUG_ON(ensure_size && cache->size < min_stripe_size);
-       return 0;
+       if (S_ISREG(src->i_mode)) {
+               btrfs_set_stack_inode_size(dst, (u64)src->i_size_high << 32 |
+                                          (u64)src->i_size);
+       }
+       if (!S_ISREG(src->i_mode) && !S_ISDIR(src->i_mode) &&
+           !S_ISLNK(src->i_mode)) {
+               if (src->i_block[0]) {
+                       btrfs_set_stack_inode_rdev(dst,
+                               old_decode_dev(src->i_block[0]));
+               } else {
+                       btrfs_set_stack_inode_rdev(dst,
+                               new_decode_dev(src->i_block[1]));
+               }
+       }
+       memset(&dst->reserved, 0, sizeof(dst->reserved));
+}
+static int ext2_check_state(struct btrfs_convert_context *cctx)
+{
+       ext2_filsys fs = cctx->fs_data;
+
+        if (!(fs->super->s_state & EXT2_VALID_FS))
+               return 1;
+       else if (fs->super->s_state & EXT2_ERROR_FS)
+               return 1;
+       else
+               return 0;
 }
 
+/* EXT2_*_FL to BTRFS_INODE_FLAG_* stringification helper */
+#define COPY_ONE_EXT2_FLAG(flags, ext2_inode, name) ({                 \
+       if (ext2_inode->i_flags & EXT2_##name##_FL)                     \
+               flags |= BTRFS_INODE_##name;                            \
+})
+
 /*
- * Remove reserved ranges from given cache_tree
- *
- * It will remove the following ranges
- * 1) 0~1M
- * 2) 2nd superblock, +64K (make sure chunks are 64K aligned)
- * 3) 3rd superblock, +64K
+ * Convert EXT2_*_FL to corresponding BTRFS_INODE_* flags
  *
- * @min_stripe must be given for safety check
- * and if @ensure_size is given, it will ensure affected cache_extent will be
- * larger than min_stripe_size
+ * Only a subset of EXT_*_FL is supported in btrfs.
  */
-static int wipe_reserved_ranges(struct cache_tree *tree, u64 min_stripe_size,
-                               int ensure_size)
+static void ext2_convert_inode_flags(struct btrfs_inode_item *dst,
+                                    struct ext2_inode *src)
 {
-       int ret;
-
-       ret = wipe_one_reserved_range(tree, 0, 1024 * 1024, min_stripe_size,
-                                     ensure_size);
-       if (ret < 0)
-               return ret;
-       ret = wipe_one_reserved_range(tree, btrfs_sb_offset(1),
-                       BTRFS_STRIPE_LEN, min_stripe_size, ensure_size);
-       if (ret < 0)
-               return ret;
-       ret = wipe_one_reserved_range(tree, btrfs_sb_offset(2),
-                       BTRFS_STRIPE_LEN, min_stripe_size, ensure_size);
-       return ret;
+       u64 flags = 0;
+
+       COPY_ONE_EXT2_FLAG(flags, src, APPEND);
+       COPY_ONE_EXT2_FLAG(flags, src, SYNC);
+       COPY_ONE_EXT2_FLAG(flags, src, IMMUTABLE);
+       COPY_ONE_EXT2_FLAG(flags, src, NODUMP);
+       COPY_ONE_EXT2_FLAG(flags, src, NOATIME);
+       COPY_ONE_EXT2_FLAG(flags, src, DIRSYNC);
+       btrfs_set_stack_inode_flags(dst, flags);
 }
 
-static int calculate_available_space(struct btrfs_convert_context *cctx)
+/*
+ * copy a single inode. do all the required works, such as cloning
+ * inode item, creating file extents and creating directory entries.
+ */
+static int ext2_copy_single_inode(struct btrfs_trans_handle *trans,
+                            struct btrfs_root *root, u64 objectid,
+                            ext2_filsys ext2_fs, ext2_ino_t ext2_ino,
+                            struct ext2_inode *ext2_inode,
+                            int datacsum, int packing, int noxattr)
 {
-       struct cache_tree *used = &cctx->used;
-       struct cache_tree *data_chunks = &cctx->data_chunks;
-       struct cache_tree *free = &cctx->free;
-       struct cache_extent *cache;
-       u64 cur_off = 0;
-       /*
-        * Twice the minimal chunk size, to allow later wipe_reserved_ranges()
-        * works without need to consider overlap
-        */
-       u64 min_stripe_size = 2 * 16 * 1024 * 1024;
        int ret;
+       struct btrfs_inode_item btrfs_inode;
 
-       /* Calculate data_chunks */
-       for (cache = first_cache_extent(used); cache;
-            cache = next_cache_extent(cache)) {
-               u64 cur_len;
+       if (ext2_inode->i_links_count == 0)
+               return 0;
 
-               if (cache->start + cache->size < cur_off)
-                       continue;
-               if (cache->start > cur_off + min_stripe_size)
-                       cur_off = cache->start;
-               cur_len = max(cache->start + cache->size - cur_off,
-                             min_stripe_size);
-               ret = add_merge_cache_extent(data_chunks, cur_off, cur_len);
-               if (ret < 0)
-                       goto out;
-               cur_off += cur_len;
+       ext2_copy_inode_item(&btrfs_inode, ext2_inode, ext2_fs->blocksize);
+       if (!datacsum && S_ISREG(ext2_inode->i_mode)) {
+               u32 flags = btrfs_stack_inode_flags(&btrfs_inode) |
+                           BTRFS_INODE_NODATASUM;
+               btrfs_set_stack_inode_flags(&btrfs_inode, flags);
        }
-       /*
-        * remove reserved ranges, so we won't ever bother relocating an old
-        * filesystem extent to other place.
-        */
-       ret = wipe_reserved_ranges(data_chunks, min_stripe_size, 1);
-       if (ret < 0)
-               goto out;
-
-       cur_off = 0;
-       /*
-        * Calculate free space
-        * Always round up the start bytenr, to avoid metadata extent corss
-        * stripe boundary, as later mkfs_convert() won't have all the extent
-        * allocation check
-        */
-       for (cache = first_cache_extent(data_chunks); cache;
-            cache = next_cache_extent(cache)) {
-               if (cache->start < cur_off)
-                       continue;
-               if (cache->start > cur_off) {
-                       u64 insert_start;
-                       u64 len;
-
-                       len = cache->start - round_up(cur_off,
-                                                     BTRFS_STRIPE_LEN);
-                       insert_start = round_up(cur_off, BTRFS_STRIPE_LEN);
+       ext2_convert_inode_flags(&btrfs_inode, ext2_inode);
 
-                       ret = add_merge_cache_extent(free, insert_start, len);
-                       if (ret < 0)
-                               goto out;
-               }
-               cur_off = cache->start + cache->size;
+       switch (ext2_inode->i_mode & S_IFMT) {
+       case S_IFREG:
+               ret = ext2_create_file_extents(trans, root, objectid,
+                       &btrfs_inode, ext2_fs, ext2_ino, datacsum, packing);
+               break;
+       case S_IFDIR:
+               ret = ext2_create_dir_entries(trans, root, objectid,
+                               &btrfs_inode, ext2_fs, ext2_ino);
+               break;
+       case S_IFLNK:
+               ret = ext2_create_symbol_link(trans, root, objectid,
+                               &btrfs_inode, ext2_fs, ext2_ino, ext2_inode);
+               break;
+       default:
+               ret = 0;
+               break;
        }
-       /* Don't forget the last range */
-       if (cctx->total_bytes > cur_off) {
-               u64 len = cctx->total_bytes - cur_off;
-               u64 insert_start;
-
-               insert_start = round_up(cur_off, BTRFS_STRIPE_LEN);
+       if (ret)
+               return ret;
 
-               ret = add_merge_cache_extent(free, insert_start, len);
-               if (ret < 0)
-                       goto out;
+       if (!noxattr) {
+               ret = ext2_copy_extended_attrs(trans, root, objectid,
+                               &btrfs_inode, ext2_fs, ext2_ino);
+               if (ret)
+                       return ret;
        }
-
-       /* Remove reserved bytes */
-       ret = wipe_reserved_ranges(free, min_stripe_size, 0);
-out:
-       return ret;
+       return btrfs_insert_inode(trans, root, objectid, &btrfs_inode);
 }
+
 /*
- * Read used space, and since we have the used space,
- * calcuate data_chunks and free for later mkfs
+ * scan ext2's inode bitmap and copy all used inodes.
  */
-static int convert_read_used_space(struct btrfs_convert_context *cctx)
+static int ext2_copy_inodes(struct btrfs_convert_context *cctx,
+                           struct btrfs_root *root,
+                           int datacsum, int packing, int noxattr, struct task_ctx *p)
 {
+       ext2_filsys ext2_fs = cctx->fs_data;
        int ret;
+       errcode_t err;
+       ext2_inode_scan ext2_scan;
+       struct ext2_inode ext2_inode;
+       ext2_ino_t ext2_ino;
+       u64 objectid;
+       struct btrfs_trans_handle *trans;
 
-       ret = cctx->convert_ops->read_used_space(cctx);
-       if (ret)
-               return ret;
+       trans = btrfs_start_transaction(root, 1);
+       if (!trans)
+               return -ENOMEM;
+       err = ext2fs_open_inode_scan(ext2_fs, 0, &ext2_scan);
+       if (err) {
+               fprintf(stderr, "ext2fs_open_inode_scan: %s\n", error_message(err));
+               return -1;
+       }
+       while (!(err = ext2fs_get_next_inode(ext2_scan, &ext2_ino,
+                                            &ext2_inode))) {
+               /* no more inodes */
+               if (ext2_ino == 0)
+                       break;
+               /* skip special inode in ext2fs */
+               if (ext2_ino < EXT2_GOOD_OLD_FIRST_INO &&
+                   ext2_ino != EXT2_ROOT_INO)
+                       continue;
+               objectid = ext2_ino + INO_OFFSET;
+               ret = ext2_copy_single_inode(trans, root,
+                                       objectid, ext2_fs, ext2_ino,
+                                       &ext2_inode, datacsum, packing,
+                                       noxattr);
+               p->cur_copy_inodes++;
+               if (ret)
+                       return ret;
+               if (trans->blocks_used >= 4096) {
+                       ret = btrfs_commit_transaction(trans, root);
+                       BUG_ON(ret);
+                       trans = btrfs_start_transaction(root, 1);
+                       BUG_ON(!trans);
+               }
+       }
+       if (err) {
+               fprintf(stderr, "ext2fs_get_next_inode: %s\n", error_message(err));
+               return -1;
+       }
+       ret = btrfs_commit_transaction(trans, root);
+       BUG_ON(ret);
+       ext2fs_close_inode_scan(ext2_scan);
 
-       ret = calculate_available_space(cctx);
        return ret;
 }
 
+static const struct btrfs_convert_operations ext2_convert_ops = {
+       .name                   = "ext2",
+       .open_fs                = ext2_open_fs,
+       .read_used_space        = ext2_read_used_space,
+       .copy_inodes            = ext2_copy_inodes,
+       .close_fs               = ext2_close_fs,
+       .check_state            = ext2_check_state,
+};
+
+#endif
+
+static const struct btrfs_convert_operations *convert_operations[] = {
+#if BTRFSCONVERT_EXT2
+       &ext2_convert_ops,
+#endif
+};
+
+static int convert_open_fs(const char *devname,
+                          struct btrfs_convert_context *cctx)
+{
+       int i;
+
+       memset(cctx, 0, sizeof(*cctx));
+
+       for (i = 0; i < ARRAY_SIZE(convert_operations); i++) {
+               int ret = convert_operations[i]->open_fs(cctx, devname);
+
+               if (ret == 0) {
+                       cctx->convert_ops = convert_operations[i];
+                       return ret;
+               }
+       }
+
+       error("no file system found to convert");
+       return -1;
+}
+
 static int do_convert(const char *devname, int datacsum, int packing,
                int noxattr, u32 nodesize, int copylabel, const char *fslabel,
                int progress, u64 features)
 {
        int ret;
        int fd = -1;
-       int is_btrfs = 0;
        u32 blocksize;
        u64 total_bytes;
        struct btrfs_root *root;
@@ -2297,6 +2387,10 @@ static int do_convert(const char *devname, int datacsum, int packing,
        ret = convert_open_fs(devname, &cctx);
        if (ret)
                goto fail;
+       ret = convert_check_state(&cctx);
+       if (ret)
+               warning(
+               "source filesystem is not clean, running filesystem check is recommended");
        ret = convert_read_used_space(&cctx);
        if (ret)
                goto fail;
@@ -2304,14 +2398,14 @@ static int do_convert(const char *devname, int datacsum, int packing,
        blocksize = cctx.blocksize;
        total_bytes = (u64)blocksize * (u64)cctx.block_count;
        if (blocksize < 4096) {
-               fprintf(stderr, "block size is too small\n");
+               error("block size is too small: %u < 4096", blocksize);
                goto fail;
        }
        if (btrfs_check_nodesize(nodesize, blocksize, features))
                goto fail;
        fd = open(devname, O_RDWR);
        if (fd < 0) {
-               fprintf(stderr, "unable to open %s\n", devname);
+               error("unable to open %s: %s", devname, strerror(errno));
                goto fail;
        }
        btrfs_parse_features_to_string(features_buf, features);
@@ -2330,34 +2424,31 @@ static int do_convert(const char *devname, int datacsum, int packing,
        mkfs_cfg.stripesize = blocksize;
        mkfs_cfg.features = features;
        /* New convert need these space */
-       mkfs_cfg.fs_uuid = malloc(BTRFS_UUID_UNPARSED_SIZE);
-       mkfs_cfg.chunk_uuid = malloc(BTRFS_UUID_UNPARSED_SIZE);
-       *(mkfs_cfg.fs_uuid) = '\0';
-       *(mkfs_cfg.chunk_uuid) = '\0';
+       memset(mkfs_cfg.chunk_uuid, 0, BTRFS_UUID_UNPARSED_SIZE);
+       memset(mkfs_cfg.fs_uuid, 0, BTRFS_UUID_UNPARSED_SIZE);
 
        ret = make_btrfs(fd, &mkfs_cfg, &cctx);
        if (ret) {
-               fprintf(stderr, "unable to create initial ctree: %s\n",
-                       strerror(-ret));
+               error("unable to create initial ctree: %s", strerror(-ret));
                goto fail;
        }
 
        root = open_ctree_fd(fd, devname, mkfs_cfg.super_bytenr,
                             OPEN_CTREE_WRITES | OPEN_CTREE_FS_PARTIAL);
        if (!root) {
-               fprintf(stderr, "unable to open ctree\n");
+               error("unable to open ctree");
                goto fail;
        }
        ret = init_btrfs(&mkfs_cfg, root, &cctx, datacsum, packing, noxattr);
        if (ret) {
-               fprintf(stderr, "unable to setup the root tree\n");
+               error("unable to setup the root tree: %d", ret);
                goto fail;
        }
 
-       printf("creating %s image file.\n", cctx.convert_ops->name);
+       printf("creating %s image file\n", cctx.convert_ops->name);
        ret = asprintf(&subvol_name, "%s_saved", cctx.convert_ops->name);
        if (ret < 0) {
-               fprintf(stderr, "error allocating subvolume name: %s_saved\n",
+               error("memory allocation failure for subvolume name: %s_saved",
                        cctx.convert_ops->name);
                goto fail;
        }
@@ -2366,17 +2457,17 @@ static int do_convert(const char *devname, int datacsum, int packing,
        key.type = BTRFS_ROOT_ITEM_KEY;
        image_root = btrfs_read_fs_root(root->fs_info, &key);
        if (!image_root) {
-               fprintf(stderr, "unable to create subvol\n");
+               error("unable to create image subvolume");
                goto fail;
        }
        ret = create_image(image_root, &mkfs_cfg, &cctx, fd,
                              mkfs_cfg.num_bytes, "image", datacsum);
        if (ret) {
-               fprintf(stderr, "error during create_image %d\n", ret);
+               error("failed to create %s/image: %d", subvol_name, ret);
                goto fail;
        }
 
-       printf("creating btrfs metadata.\n");
+       printf("creating btrfs metadata");
        ctx.max_copy_inodes = (cctx.inodes_count - cctx.free_inodes_count);
        ctx.cur_copy_inodes = 0;
 
@@ -2387,7 +2478,7 @@ static int do_convert(const char *devname, int datacsum, int packing,
        }
        ret = copy_inodes(&cctx, root, datacsum, packing, noxattr, &ctx);
        if (ret) {
-               fprintf(stderr, "error during copy_inodes %d\n", ret);
+               error("error during copy_inodes %d", ret);
                goto fail;
        }
        if (progress) {
@@ -2396,6 +2487,10 @@ static int do_convert(const char *devname, int datacsum, int packing,
        }
 
        image_root = link_subvol(root, subvol_name, CONV_IMAGE_SUBVOL_OBJECTID);
+       if (!image_root) {
+               error("unable to link subvolume %s", subvol_name);
+               goto fail;
+       }
 
        free(subvol_name);
 
@@ -2403,16 +2498,15 @@ static int do_convert(const char *devname, int datacsum, int packing,
        if (copylabel == 1) {
                __strncpy_null(root->fs_info->super_copy->label,
                                cctx.volume_name, BTRFS_LABEL_SIZE - 1);
-               fprintf(stderr, "copy label '%s'\n",
-                               root->fs_info->super_copy->label);
+               printf("copy label '%s'\n", root->fs_info->super_copy->label);
        } else if (copylabel == -1) {
                strcpy(root->fs_info->super_copy->label, fslabel);
-               fprintf(stderr, "set label to '%s'\n", fslabel);
+               printf("set label to '%s'\n", fslabel);
        }
 
        ret = close_ctree(root);
        if (ret) {
-               fprintf(stderr, "error during close_ctree %d\n", ret);
+               error("close_ctree failed: %d", ret);
                goto fail;
        }
        convert_close_fs(&cctx);
@@ -2424,32 +2518,28 @@ static int do_convert(const char *devname, int datacsum, int packing,
         */
        ret = migrate_super_block(fd, mkfs_cfg.super_bytenr, blocksize);
        if (ret) {
-               fprintf(stderr, "unable to migrate super block\n");
+               error("unable to migrate super block: %d", ret);
                goto fail;
        }
-       is_btrfs = 1;
 
        root = open_ctree_fd(fd, devname, 0,
                        OPEN_CTREE_WRITES | OPEN_CTREE_FS_PARTIAL);
        if (!root) {
-               fprintf(stderr, "unable to open ctree\n");
+               error("unable to open ctree for finalization");
                goto fail;
        }
        root->fs_info->finalize_on_close = 1;
        close_ctree(root);
        close(fd);
 
-       printf("conversion complete.\n");
+       printf("conversion complete");
        return 0;
 fail:
        clean_convert_context(&cctx);
        if (fd != -1)
                close(fd);
-       if (is_btrfs)
-               fprintf(stderr,
-                       "WARNING: an error occurred during chunk mapping fixup, filesystem mountable but not finalized\n");
-       else
-               fprintf(stderr, "conversion aborted\n");
+       warning(
+"an error occurred during conversion, filesystem is partially created but not finalized and not mountable");
        return -1;
 }
 
@@ -2547,7 +2637,7 @@ static int may_rollback(struct btrfs_root *root)
 
                num_stripes = multi->num_stripes;
                physical = multi->stripes[0].physical;
-               kfree(multi);
+               free(multi);
 
                if (num_stripes != 1) {
                        error("num stripes for bytenr %llu is not 1", bytenr);
@@ -2614,24 +2704,24 @@ static int do_rollback(const char *devname)
 
        fd = open(devname, O_RDWR);
        if (fd < 0) {
-               fprintf(stderr, "unable to open %s\n", devname);
+               error("unable to open %s: %s", devname, strerror(errno));
                goto fail;
        }
        root = open_ctree_fd(fd, devname, 0, OPEN_CTREE_WRITES);
        if (!root) {
-               fprintf(stderr, "unable to open ctree\n");
+               error("unable to open ctree");
                goto fail;
        }
        ret = may_rollback(root);
        if (ret < 0) {
-               fprintf(stderr, "unable to do rollback\n");
+               error("unable to do rollback: %d", ret);
                goto fail;
        }
 
        sectorsize = root->sectorsize;
        buf = malloc(sectorsize);
        if (!buf) {
-               fprintf(stderr, "unable to allocate memory\n");
+               error("unable to allocate memory");
                goto fail;
        }
 
@@ -2644,12 +2734,10 @@ static int do_rollback(const char *devname)
                                0);
        btrfs_release_path(&path);
        if (ret > 0) {
-               fprintf(stderr,
-               "ERROR: unable to convert ext2 image subvolume, is it deleted?\n");
+               error("unable to convert ext2 image subvolume, is it deleted?");
                goto fail;
        } else if (ret < 0) {
-               fprintf(stderr,
-                       "ERROR: unable to open ext2_saved, id=%llu: %s\n",
+               error("unable to open ext2_saved, id %llu: %s",
                        (unsigned long long)key.objectid, strerror(-ret));
                goto fail;
        }
@@ -2659,8 +2747,8 @@ static int do_rollback(const char *devname)
        key.offset = (u64)-1;
        image_root = btrfs_read_fs_root(root->fs_info, &key);
        if (!image_root || IS_ERR(image_root)) {
-               fprintf(stderr, "unable to open subvol %llu\n",
-                       (unsigned long long)key.objectid);
+               error("unable to open subvolume %llu: %ld",
+                       (unsigned long long)key.objectid, PTR_ERR(image_root));
                goto fail;
        }
 
@@ -2669,7 +2757,7 @@ static int do_rollback(const char *devname)
        dir = btrfs_lookup_dir_item(NULL, image_root, &path,
                                   root_dir, name, strlen(name), 0);
        if (!dir || IS_ERR(dir)) {
-               fprintf(stderr, "unable to find file %s\n", name);
+               error("unable to find file %s: %ld", name, PTR_ERR(dir));
                goto fail;
        }
        leaf = path.nodes[0];
@@ -2680,7 +2768,7 @@ static int do_rollback(const char *devname)
 
        ret = btrfs_lookup_inode(NULL, image_root, &path, &key, 0);
        if (ret) {
-               fprintf(stderr, "unable to find inode item\n");
+               error("unable to find inode item: %d", ret);
                goto fail;
        }
        leaf = path.nodes[0];
@@ -2690,10 +2778,10 @@ static int do_rollback(const char *devname)
 
        key.objectid = objectid;
        key.offset = 0;
-       btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
+       key.type = BTRFS_EXTENT_DATA_KEY;
        ret = btrfs_search_slot(NULL, image_root, &key, &path, 0, 0);
        if (ret != 0) {
-               fprintf(stderr, "unable to find first file extent\n");
+               error("unable to find first file extent: %d", ret);
                btrfs_release_path(&path);
                goto fail;
        }
@@ -2710,7 +2798,7 @@ static int do_rollback(const char *devname)
 
                btrfs_item_key_to_cpu(leaf, &key, path.slots[0]);
                if (key.objectid != objectid || key.offset != offset ||
-                   btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
+                   key.type != BTRFS_EXTENT_DATA_KEY)
                        break;
 
                fi = btrfs_item_ptr(leaf, path.slots[0],
@@ -2756,8 +2844,10 @@ next_extent:
        btrfs_release_path(&path);
 
        if (offset < total_bytes) {
-               fprintf(stderr, "unable to build extent mapping\n");
-               fprintf(stderr, "converted filesystem after balance is unable to rollback\n");
+               error("unable to build extent mapping (offset %llu, total_bytes %llu)",
+                               (unsigned long long)offset,
+                               (unsigned long long)total_bytes);
+               error("converted filesystem after balance is unable to rollback");
                goto fail;
        }
 
@@ -2765,13 +2855,16 @@ next_extent:
        first_free &= ~((u64)sectorsize - 1);
        /* backup for extent #0 should exist */
        if(!test_range_bit(&io_tree, 0, first_free - 1, EXTENT_LOCKED, 1)) {
-               fprintf(stderr, "no backup for the first extent\n");
+               error("no backup for the first extent");
                goto fail;
        }
        /* force no allocation from system block group */
        root->fs_info->system_allocs = -1;
        trans = btrfs_start_transaction(root, 1);
-       BUG_ON(!trans);
+       if (!trans) {
+               error("unable to start transaction");
+               goto fail;
+       }
        /*
         * recow the whole chunk tree, this will remove all chunk tree blocks
         * from system block group
@@ -2806,22 +2899,28 @@ next_extent:
        }
        /* only extent #0 left in system block group? */
        if (num_bytes > first_free) {
-               fprintf(stderr, "unable to empty system block group\n");
+               error(
+       "unable to empty system block group (num_bytes %llu, first_free %llu",
+                               (unsigned long long)num_bytes,
+                               (unsigned long long)first_free);
                goto fail;
        }
        /* create a system chunk that maps the whole device */
        ret = prepare_system_chunk_sb(root->fs_info->super_copy);
        if (ret) {
-               fprintf(stderr, "unable to update system chunk\n");
+               error("unable to update system chunk: %d", ret);
                goto fail;
        }
 
        ret = btrfs_commit_transaction(trans, root);
-       BUG_ON(ret);
+       if (ret) {
+               error("transaction commit failed: %d", ret);
+               goto fail;
+       }
 
        ret = close_ctree(root);
        if (ret) {
-               fprintf(stderr, "error during close_ctree %d\n", ret);
+               error("close_ctree failed: %d", ret);
                goto fail;
        }
 
@@ -2833,9 +2932,8 @@ next_extent:
                        break;
                ret = pwrite(fd, buf, sectorsize, bytenr);
                if (ret != sectorsize) {
-                       fprintf(stderr,
-                               "error during zeroing superblock %d: %d\n",
-                               i, ret);
+                       error("zeroing superblock mirror %d failed: %d",
+                                       i, ret);
                        goto fail;
                }
        }
@@ -2861,13 +2959,15 @@ next_extent:
                        }
                        ret = pread(fd, buf, sectorsize, bytenr);
                        if (ret < 0) {
-                               fprintf(stderr, "error during pread %d\n", ret);
+                               error("reading superblock at %llu failed: %d",
+                                               (unsigned long long)bytenr, ret);
                                goto fail;
                        }
                        BUG_ON(ret != sectorsize);
                        ret = pwrite(fd, buf, sectorsize, start);
                        if (ret < 0) {
-                               fprintf(stderr, "error during pwrite %d\n", ret);
+                               error("writing superblock at %llu failed: %d",
+                                               (unsigned long long)start, ret);
                                goto fail;
                        }
                        BUG_ON(ret != sectorsize);
@@ -2878,8 +2978,8 @@ next_sector:
        }
 
        ret = fsync(fd);
-       if (ret) {
-               fprintf(stderr, "error during fsync %d\n", ret);
+       if (ret < 0) {
+               error("fsync failed: %s", strerror(errno));
                goto fail;
        }
        /*
@@ -2887,33 +2987,35 @@ next_sector:
         */
        ret = pread(fd, buf, sectorsize, sb_bytenr);
        if (ret < 0) {
-               fprintf(stderr, "error during pread %d\n", ret);
+               error("reading primary superblock failed: %s",
+                               strerror(errno));
                goto fail;
        }
        BUG_ON(ret != sectorsize);
        ret = pwrite(fd, buf, sectorsize, BTRFS_SUPER_INFO_OFFSET);
        if (ret < 0) {
-               fprintf(stderr, "error during pwrite %d\n", ret);
+               error("writing primary superblock failed: %s",
+                               strerror(errno));
                goto fail;
        }
        BUG_ON(ret != sectorsize);
        ret = fsync(fd);
-       if (ret) {
-               fprintf(stderr, "error during fsync %d\n", ret);
+       if (ret < 0) {
+               error("fsync failed: %s", strerror(errno));
                goto fail;
        }
 
        close(fd);
        free(buf);
        extent_io_tree_cleanup(&io_tree);
-       printf("rollback complete.\n");
+       printf("rollback complete\n");
        return 0;
 
 fail:
        if (fd != -1)
                close(fd);
        free(buf);
-       fprintf(stderr, "rollback aborted.\n");
+       error("rollback aborted");
        return -1;
 }
 
@@ -2931,6 +3033,9 @@ static void print_usage(void)
        printf("\t-p|--progress          show converting progress (default)\n");
        printf("\t-O|--features LIST     comma separated list of filesystem features\n");
        printf("\t--no-progress          show only overview, not the detailed progress\n");
+       printf("\n");
+       printf("Supported filesystems:\n");
+       printf("\text2/3/4: %s\n", BTRFSCONVERT_EXT2 ? "yes" : "no");
 }
 
 int main(int argc, char *argv[])
@@ -2989,8 +3094,8 @@ int main(int argc, char *argv[])
                        case 'l':
                                copylabel = -1;
                                if (strlen(optarg) >= BTRFS_LABEL_SIZE) {
-                                       fprintf(stderr,
-                               "WARNING: label too long, trimmed to %d bytes\n",
+                                       warning(
+                                       "label too long, trimmed to %d bytes",
                                                BTRFS_LABEL_SIZE - 1);
                                }
                                __strncpy_null(fslabel, optarg, BTRFS_LABEL_SIZE - 1);
@@ -3007,8 +3112,7 @@ int main(int argc, char *argv[])
 
                                tmp = btrfs_parse_fs_features(tmp, &features);
                                if (tmp) {
-                                       fprintf(stderr,
-                                               "Unrecognized filesystem feature '%s'\n",
+                                       error("unrecognized filesystem feature: %s",
                                                        tmp);
                                        free(orig);
                                        exit(1);
@@ -3024,8 +3128,7 @@ int main(int argc, char *argv[])
 
                                        btrfs_parse_features_to_string(buf,
                                                features & ~BTRFS_CONVERT_ALLOWED_FEATURES);
-                                       fprintf(stderr,
-                                               "ERROR: features not allowed for convert: %s\n",
+                                       error("features not allowed for convert: %s",
                                                buf);
                                        exit(1);
                                }
@@ -3061,11 +3164,10 @@ int main(int argc, char *argv[])
        file = argv[optind];
        ret = check_mounted(file);
        if (ret < 0) {
-               fprintf(stderr, "Could not check mount status: %s\n",
-                       strerror(-ret));
+               error("could not check mount status: %s", strerror(-ret));
                return 1;
        } else if (ret) {
-               fprintf(stderr, "%s is mounted\n", file);
+               error("%s is mounted", file);
                return 1;
        }