Btrfs: progress on file_write
authorChris Mason <chris.mason@oracle.com>
Tue, 17 Apr 2007 17:26:50 +0000 (13:26 -0400)
committerDavid Woodhouse <dwmw2@hera.kernel.org>
Tue, 17 Apr 2007 17:26:50 +0000 (13:26 -0400)
Signed-off-by: Chris Mason <chris.mason@oracle.com>
fs/btrfs/ctree.c
fs/btrfs/ctree.h
fs/btrfs/extent-tree.c
fs/btrfs/file-item.c
fs/btrfs/super.c

index 6b76fd9..43d4779 100644 (file)
@@ -1249,6 +1249,63 @@ static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
        return ret;
 }
 
+int btrfs_truncate_item(struct btrfs_trans_handle *trans,
+                       struct btrfs_root *root,
+                       struct btrfs_path *path,
+                       u32 new_size)
+{
+       int ret = 0;
+       int slot;
+       int slot_orig;
+       struct btrfs_leaf *leaf;
+       struct buffer_head *leaf_buf;
+       u32 nritems;
+       unsigned int data_end;
+       unsigned int old_data_start;
+       unsigned int old_size;
+       unsigned int size_diff;
+       int i;
+
+       slot_orig = path->slots[0];
+       leaf_buf = path->nodes[0];
+       leaf = btrfs_buffer_leaf(leaf_buf);
+
+       nritems = btrfs_header_nritems(&leaf->header);
+       data_end = leaf_data_end(root, leaf);
+
+       slot = path->slots[0];
+       old_data_start = btrfs_item_offset(leaf->items + slot);
+       old_size = btrfs_item_size(leaf->items + slot);
+       BUG_ON(old_size <= new_size);
+       size_diff = old_size - new_size;
+
+       BUG_ON(slot < 0);
+       BUG_ON(slot >= nritems);
+
+       /*
+        * item0..itemN ... dataN.offset..dataN.size .. data0.size
+        */
+       /* first correct the data pointers */
+       for (i = slot; i < nritems; i++) {
+               u32 ioff = btrfs_item_offset(leaf->items + i);
+               btrfs_set_item_offset(leaf->items + i,
+                                     ioff + size_diff);
+       }
+       /* shift the data */
+printk("truncate item, new_size %u old_size %u, diff %u, bufp %p, dst, %p, num %u, old_data_start %u, data_end %u\n", new_size, old_size, size_diff, leaf, btrfs_leaf_data(leaf) + data_end + size_diff, old_data_start-data_end, old_data_start, data_end);
+       btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
+                     data_end + size_diff, btrfs_leaf_data(leaf) +
+                     data_end, old_data_start + new_size - data_end);
+       btrfs_set_item_size(leaf->items + slot, new_size);
+       btrfs_mark_buffer_dirty(leaf_buf);
+
+       ret = 0;
+       if (btrfs_leaf_free_space(root, leaf) < 0)
+               BUG();
+       check_leaf(root, path, 0);
+       return ret;
+}
+
 int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root
                      *root, struct btrfs_path *path, u32 data_size)
 {
index 796f19d..ca3ab16 100644 (file)
@@ -999,7 +999,7 @@ static inline void btrfs_mark_buffer_dirty(struct buffer_head *bh)
        ((type *)(btrfs_leaf_data(leaf) + \
        btrfs_item_offset((leaf)->items + (slot))))
 
-/* extent-item.c */
+/* extent-tree.c */
 int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
                       struct btrfs_root *root);
 struct buffer_head *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
@@ -1013,9 +1013,16 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                      *root, u64 blocknr, u64 num_blocks, int pin);
 int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans, struct
                               btrfs_root *root);
+int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
+                               struct btrfs_root *root,
+                               u64 blocknr, u64 num_blocks);
 /* ctree.c */
 int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root
                      *root, struct btrfs_path *path, u32 data_size);
+int btrfs_truncate_item(struct btrfs_trans_handle *trans,
+                       struct btrfs_root *root,
+                       struct btrfs_path *path,
+                       u32 new_size);
 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
                      *root, struct btrfs_key *key, struct btrfs_path *p, int
                      ins_len, int cow);
@@ -1073,11 +1080,10 @@ int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
                       struct btrfs_key *location, int mod);
 
 /* file-item.c */
-int btrfs_alloc_file_extent(struct btrfs_trans_handle *trans,
+int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
                               struct btrfs_root *root,
-                              u64 objectid, u64 offset,
-                              u64 num_blocks, u64 hint_block,
-                              u64 *result);
+                              u64 objectid, u64 pos, u64 offset,
+                              u64 num_blocks);
 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
                             struct btrfs_root *root,
                             struct btrfs_path *path, u64 objectid,
@@ -1090,6 +1096,11 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
 int btrfs_csum_verify_file_block(struct btrfs_root *root,
                                 u64 objectid, u64 offset,
                                 char *data, size_t len);
+struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
+                                         struct btrfs_root *root,
+                                         struct btrfs_path *path,
+                                         u64 objectid, u64 offset,
+                                         int cow);
 /* super.c */
 extern struct subsystem btrfs_subsys;
 
index d560831..2cee9df 100644 (file)
@@ -12,8 +12,9 @@ static int finish_current_insert(struct btrfs_trans_handle *trans, struct
 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
                               btrfs_root *extent_root);
 
-static int inc_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
-                        *root, u64 blocknr, u64 num_blocks)
+int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
+                               struct btrfs_root *root,
+                               u64 blocknr, u64 num_blocks)
 {
        struct btrfs_path *path;
        int ret;
@@ -50,8 +51,9 @@ static int inc_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
        return 0;
 }
 
-static int lookup_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
-                           *root, u64 blocknr, u64 num_blocks, u32 *refs)
+static int lookup_extent_ref(struct btrfs_trans_handle *trans,
+                            struct btrfs_root *root, u64 blocknr,
+                            u64 num_blocks, u32 *refs)
 {
        struct btrfs_path *path;
        int ret;
@@ -80,7 +82,7 @@ static int lookup_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
 int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
                       struct btrfs_root *root)
 {
-       return inc_block_ref(trans, root, bh_blocknr(root->node), 1);
+       return btrfs_inc_extent_ref(trans, root, bh_blocknr(root->node), 1);
 }
 
 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
@@ -107,13 +109,13 @@ int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                                continue;
                        fi = btrfs_item_ptr(buf_leaf, i,
                                            struct btrfs_file_extent_item);
-                       ret = inc_block_ref(trans, root,
+                       ret = btrfs_inc_extent_ref(trans, root,
                                    btrfs_file_extent_disk_blocknr(fi),
                                    btrfs_file_extent_disk_num_blocks(fi));
                        BUG_ON(ret);
                } else {
                        blocknr = btrfs_node_blockptr(buf_node, i);
-                       ret = inc_block_ref(trans, root, blocknr, 1);
+                       ret = btrfs_inc_extent_ref(trans, root, blocknr, 1);
                        BUG_ON(ret);
                }
        }
@@ -563,7 +565,7 @@ static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
 
        WARN_ON(*level < 0);
        WARN_ON(*level >= BTRFS_MAX_LEVEL);
-       ret = lookup_block_ref(trans, root, bh_blocknr(path->nodes[*level]),
+       ret = lookup_extent_ref(trans, root, bh_blocknr(path->nodes[*level]),
                               1, &refs);
        BUG_ON(ret);
        if (refs > 1)
@@ -587,7 +589,7 @@ static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
                }
                blocknr = btrfs_node_blockptr(btrfs_buffer_node(cur),
                                              path->slots[*level]);
-               ret = lookup_block_ref(trans, root, blocknr, 1, &refs);
+               ret = lookup_extent_ref(trans, root, blocknr, 1, &refs);
                BUG_ON(ret);
                if (refs != 1) {
                        path->slots[*level]++;
index 93d42d6..f49968a 100644 (file)
@@ -6,13 +6,11 @@
 #define MAX_CSUM_ITEMS(r) ((((BTRFS_LEAF_DATA_SIZE(r) - \
                                 sizeof(struct btrfs_item)) / \
                                sizeof(struct btrfs_csum_item)) - 1))
-int btrfs_alloc_file_extent(struct btrfs_trans_handle *trans,
+int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
                               struct btrfs_root *root,
-                              u64 objectid, u64 offset,
-                              u64 num_blocks, u64 hint_block,
-                              u64 *result)
+                              u64 objectid, u64 pos,
+                              u64 offset, u64 num_blocks)
 {
-       struct btrfs_key ins;
        int ret = 0;
        struct btrfs_file_extent_item *item;
        struct btrfs_key file_key;
@@ -21,11 +19,13 @@ int btrfs_alloc_file_extent(struct btrfs_trans_handle *trans,
        path = btrfs_alloc_path();
        BUG_ON(!path);
        btrfs_init_path(path);
+       /*
        ret = btrfs_alloc_extent(trans, root, num_blocks, hint_block,
                                 (u64)-1, &ins);
+                                */
        BUG_ON(ret);
        file_key.objectid = objectid;
-       file_key.offset = offset;
+       file_key.offset = pos;
        file_key.flags = 0;
        btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
 
@@ -34,21 +34,22 @@ int btrfs_alloc_file_extent(struct btrfs_trans_handle *trans,
        BUG_ON(ret);
        item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
                              struct btrfs_file_extent_item);
-       btrfs_set_file_extent_disk_blocknr(item, ins.objectid);
-       btrfs_set_file_extent_disk_num_blocks(item, ins.offset);
+       btrfs_set_file_extent_disk_blocknr(item, offset);
+       btrfs_set_file_extent_disk_num_blocks(item, num_blocks);
        btrfs_set_file_extent_offset(item, 0);
-       btrfs_set_file_extent_num_blocks(item, ins.offset);
+       btrfs_set_file_extent_num_blocks(item, num_blocks);
        btrfs_set_file_extent_generation(item, trans->transid);
        btrfs_mark_buffer_dirty(path->nodes[0]);
-       *result = ins.objectid;
        btrfs_release_path(root, path);
        btrfs_free_path(path);
        return 0;
 }
 
-static struct btrfs_csum_item *__lookup_csum_item(struct btrfs_root *root,
-                                                 struct btrfs_path *path,
-                                                 u64 objectid, u64 offset)
+struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
+                                         struct btrfs_root *root,
+                                         struct btrfs_path *path,
+                                         u64 objectid, u64 offset,
+                                         int cow)
 {
        int ret;
        struct btrfs_key file_key;
@@ -61,19 +62,23 @@ static struct btrfs_csum_item *__lookup_csum_item(struct btrfs_root *root,
        file_key.offset = offset;
        file_key.flags = 0;
        btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
-       ret = btrfs_search_slot(NULL, root, &file_key, path, 0, 0);
+printk("__lookup for %Lu\n", offset);
+       ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
        if (ret < 0)
                goto fail;
        leaf = btrfs_buffer_leaf(path->nodes[0]);
        if (ret > 0) {
                ret = 1;
-               if (path->slots[0] == 0)
+               if (path->slots[0] == 0) {
+printk("fail1\n");
                        goto fail;
+               }
                path->slots[0]--;
                btrfs_disk_key_to_cpu(&found_key,
                                      &leaf->items[path->slots[0]].key);
                if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
                    found_key.objectid != objectid) {
+printk("fail2 type %u %Lu %Lu\n", btrfs_key_type(&found_key), found_key.objectid, objectid);
                        goto fail;
                }
                csum_offset = (offset - found_key.offset) >>
@@ -81,6 +86,7 @@ static struct btrfs_csum_item *__lookup_csum_item(struct btrfs_root *root,
                if (csum_offset >=
                    btrfs_item_size(leaf->items + path->slots[0]) /
                    sizeof(struct btrfs_csum_item)) {
+printk("fail3, csum offset %lu size %u\n", csum_offset, btrfs_item_size(leaf->items + path->slots[0]) / sizeof(struct btrfs_csum_item));
                        goto fail;
                }
        }
@@ -89,7 +95,7 @@ static struct btrfs_csum_item *__lookup_csum_item(struct btrfs_root *root,
        return item;
 fail:
        if (ret > 0)
-               ret = -EIO;
+               ret = -ENOENT;
        return ERR_PTR(ret);
 }
 
@@ -105,7 +111,7 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
        int cow = mod != 0;
        struct btrfs_csum_item *csum_item;
 
-       csum_item = __lookup_csum_item(root, path, objectid, offset);
+       csum_item = btrfs_lookup_csum(trans, root, path, objectid, offset, 0);
        if (IS_ERR(csum_item))
                return PTR_ERR(csum_item);
        file_key.objectid = objectid;
@@ -113,7 +119,9 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
        file_key.flags = 0;
        btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
        btrfs_release_path(root, path);
+printk("lookup file extent searches for %Lu\n", file_key.offset);
        ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
+printk("ret is %d\n", ret);
        return ret;
 }
 
@@ -134,17 +142,23 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
        path = btrfs_alloc_path();
        BUG_ON(!path);
        btrfs_init_path(path);
+
+       item = btrfs_lookup_csum(trans, root, path, objectid, offset, 0);
+       if (!IS_ERR(item))
+               goto found;
+       btrfs_release_path(root, path);
        file_key.objectid = objectid;
        file_key.offset = offset;
        file_key.flags = 0;
        btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+printk("searching for csum %Lu %Lu\n", objectid, offset);
        ret = btrfs_search_slot(trans, root, &file_key, path,
                                sizeof(struct btrfs_csum_item), 1);
+printk("ret %d\n", ret);
        if (ret < 0)
                goto fail;
        if (ret == 0) {
-               csum_offset = 0;
-               goto csum;
+               BUG();
        }
        if (path->slots[0] == 0) {
                btrfs_release_path(root, path);
@@ -153,12 +167,15 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
        path->slots[0]--;
        leaf = btrfs_buffer_leaf(path->nodes[0]);
        btrfs_disk_key_to_cpu(&found_key, &leaf->items[path->slots[0]].key);
+printk("found key %Lu %Lu %u\n", found_key.objectid, found_key.offset, found_key.flags);
        csum_offset = (offset - found_key.offset) >>
                        root->fs_info->sb->s_blocksize_bits;
+printk("csum_offset %Lu\n", csum_offset);
        if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
            found_key.objectid != objectid ||
            csum_offset >= MAX_CSUM_ITEMS(root)) {
                btrfs_release_path(root, path);
+printk("insert1\n");
                goto insert;
        }
        if (csum_offset >= btrfs_item_size(leaf->items + path->slots[0]) /
@@ -166,11 +183,13 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
                ret = btrfs_extend_item(trans, root, path,
                                        sizeof(struct btrfs_csum_item));
                BUG_ON(ret);
+printk("item extended\n");
                goto csum;
        }
 
 insert:
        csum_offset = 0;
+printk("inserting item %Lu %Lu %u\n", file_key.objectid, file_key.offset, file_key.flags);
        ret = btrfs_insert_empty_item(trans, root, path, &file_key,
                                      sizeof(struct btrfs_csum_item));
        if (ret != 0 && ret != -EEXIST)
@@ -180,12 +199,14 @@ csum:
                              struct btrfs_csum_item);
        ret = 0;
        item += csum_offset;
+found:
        ret = btrfs_csum_data(root, data, len, item->csum);
        btrfs_set_csum_extent_offset(item, extent_offset);
        btrfs_mark_buffer_dirty(path->nodes[0]);
 fail:
        btrfs_release_path(root, path);
        btrfs_free_path(path);
+printk("return ret %d\n", ret);
        return ret;
 }
 
@@ -208,7 +229,7 @@ int btrfs_csum_verify_file_block(struct btrfs_root *root,
        btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
        mutex_lock(&root->fs_info->fs_mutex);
 
-       item = __lookup_csum_item(root, path, objectid, offset);
+       item = btrfs_lookup_csum(NULL, root, path, objectid, offset, 0);
        if (IS_ERR(item)) {
                ret = PTR_ERR(item);
                goto fail;
index ec68999..6a56416 100644 (file)
@@ -1089,7 +1089,6 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
 
        extent_start = btrfs_disk_key_offset(&leaf->items[path->slots[0]].key);
        extent_start = extent_start >> inode->i_blkbits;
-       extent_start += btrfs_file_extent_offset(item);
        extent_end = extent_start + btrfs_file_extent_num_blocks(item);
        if (iblock >= extent_start && iblock < extent_end) {
                err = 0;
@@ -1103,6 +1102,7 @@ allocate:
                err = 0;
                goto out;
        }
+#if 0
        ret = btrfs_alloc_file_extent(trans, root, objectid,
                                      iblock << inode->i_blkbits,
                                      1, extent_end, &blocknr);
@@ -1115,9 +1115,11 @@ allocate:
        map_bh(result, inode->i_sb, blocknr);
 
        btrfs_map_bh_to_logical(root, result, blocknr);
+#endif
 out:
        btrfs_release_path(root, path);
        btrfs_free_path(path);
+printk("mapping iblock %lu to %lu\n", iblock, result->b_blocknr);
        if (trans)
                btrfs_end_transaction(trans, root);
        return err;
@@ -1273,8 +1275,244 @@ failed:
        return err;
 }
 
-static int prepare_pages(struct btrfs_trans_handle *trans,
-                        struct btrfs_root *root,
+static int drop_csums(struct btrfs_trans_handle *trans,
+                         struct btrfs_root *root,
+                         struct inode *inode,
+                         u64 start, u64 end)
+{
+       struct btrfs_path *path;
+       struct btrfs_leaf *leaf;
+       struct btrfs_key key;
+       int slot;
+       struct btrfs_csum_item *item;
+       char *old_block = NULL;
+       u64 cur = start;
+       u64 found_end;
+       u64 num_csums;
+       u64 item_size;
+       int ret;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+       while(cur < end) {
+               item = btrfs_lookup_csum(trans, root, path,
+                                        inode->i_ino, cur, 1);
+               if (IS_ERR(item)) {
+                       cur += root->blocksize;
+                       continue;
+               }
+               leaf = btrfs_buffer_leaf(path->nodes[0]);
+               slot = path->slots[0];
+               btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
+               item_size = btrfs_item_size(leaf->items + slot);
+               num_csums = item_size / sizeof(struct btrfs_csum_item);
+               found_end = key.offset + (num_csums << inode->i_blkbits);
+               cur = found_end;
+
+               if (found_end > end) {
+                       char *src;
+                       old_block = kmalloc(root->blocksize, GFP_NOFS);
+                       src = btrfs_item_ptr(leaf, slot, char);
+                       memcpy(old_block, src, item_size);
+               }
+               if (key.offset < start) {
+                       u64 new_size = (start - key.offset) >>
+                                       inode->i_blkbits;
+                       new_size *= sizeof(struct btrfs_csum_item);
+                       ret = btrfs_truncate_item(trans, root, path, new_size);
+                       BUG_ON(ret);
+               } else {
+                       btrfs_del_item(trans, root, path);
+               }
+               btrfs_release_path(root, path);
+               if (found_end > end) {
+                       char *dst;
+                       int i;
+                       int new_size;
+
+                       num_csums = (found_end - end) >> inode->i_blkbits;
+                       new_size = num_csums * sizeof(struct btrfs_csum_item);
+                       key.offset = end;
+                       ret = btrfs_insert_empty_item(trans, root, path,
+                                                     &key, new_size);
+                       BUG_ON(ret);
+                       dst = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
+                                            path->slots[0], char);
+                       memcpy(dst, old_block + item_size - new_size,
+                              new_size);
+                       item = (struct btrfs_csum_item *)dst;
+                       for (i = 0; i < num_csums; i++) {
+                               btrfs_set_csum_extent_offset(item, end);
+                               item++;
+                       }
+                       mark_buffer_dirty(path->nodes[0]);
+                       kfree(old_block);
+                       break;
+               }
+       }
+       btrfs_free_path(path);
+       return 0;
+}
+
+static int drop_extents(struct btrfs_trans_handle *trans,
+                         struct btrfs_root *root,
+                         struct inode *inode,
+                         u64 start, u64 end)
+{
+       int ret;
+       struct btrfs_key key;
+       struct btrfs_leaf *leaf;
+       int slot;
+       struct btrfs_file_extent_item *extent;
+       u64 extent_end;
+       int keep;
+       struct btrfs_file_extent_item old;
+       struct btrfs_path *path;
+       u64 search_start = start;
+       int bookend;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+search_again:
+printk("drop extent inode %lu start %Lu end %Lu\n", inode->i_ino, start, end);
+       ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
+                                      search_start, -1);
+       if (ret != 0) {
+printk("lookup failed\n");
+               goto out;
+       }
+       while(1) {
+               keep = 0;
+               bookend = 0;
+               leaf = btrfs_buffer_leaf(path->nodes[0]);
+               slot = path->slots[0];
+               btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
+
+printk("found key %Lu %Lu %u\n", key.objectid, key.offset, key.flags);
+
+               extent = btrfs_item_ptr(leaf, slot,
+                                       struct btrfs_file_extent_item);
+               extent_end = key.offset +
+                       (btrfs_file_extent_num_blocks(extent) <<
+                        inode->i_blkbits);
+printk("extent end is %Lu\n", extent_end);
+               if (key.offset >= end || key.objectid != inode->i_ino) {
+                       ret = 0;
+                       goto out;
+               }
+               if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
+                       goto next_leaf;
+
+               if (end < extent_end && end >= key.offset) {
+                       memcpy(&old, extent, sizeof(old));
+                       ret = btrfs_inc_extent_ref(trans, root,
+                                  btrfs_file_extent_disk_blocknr(&old),
+                                  btrfs_file_extent_disk_num_blocks(&old));
+                       BUG_ON(ret);
+                       bookend = 1;
+               }
+
+               if (start > key.offset) {
+                       u64 new_num;
+                       /* truncate existing extent */
+                       keep = 1;
+                       WARN_ON(start & (root->blocksize - 1));
+                       new_num = (start - key.offset) >> inode->i_blkbits;
+printk("truncating existing extent, was %Lu ", btrfs_file_extent_num_blocks(extent));
+                       btrfs_set_file_extent_num_blocks(extent, new_num);
+printk("now %Lu\n", btrfs_file_extent_num_blocks(extent));
+
+                       mark_buffer_dirty(path->nodes[0]);
+               }
+               if (!keep) {
+                       u64 disk_blocknr;
+                       u64 disk_num_blocks;
+printk("del old\n");
+                       disk_blocknr = btrfs_file_extent_disk_blocknr(extent);
+                       disk_num_blocks =
+                               btrfs_file_extent_disk_num_blocks(extent);
+                       search_start = key.offset +
+                               (btrfs_file_extent_num_blocks(extent) <<
+                               inode->i_blkbits);
+                       ret = btrfs_del_item(trans, root, path);
+                       BUG_ON(ret);
+                       btrfs_release_path(root, path);
+
+                       ret = btrfs_free_extent(trans, root, disk_blocknr,
+                                               disk_num_blocks, 0);
+
+                       BUG_ON(ret);
+                       if (!bookend && search_start >= end) {
+                               ret = 0;
+                               goto out;
+                       }
+                       if (!bookend)
+                               goto search_again;
+               }
+               if (bookend) {
+                       /* create bookend */
+                       struct btrfs_key ins;
+printk("bookend! extent end %Lu\n", extent_end);
+                       ins.objectid = inode->i_ino;
+                       ins.offset = end;
+                       ins.flags = 0;
+                       btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
+
+                       btrfs_release_path(root, path);
+                       ret = drop_csums(trans, root, inode, start, end);
+                       BUG_ON(ret);
+                       ret = btrfs_insert_empty_item(trans, root, path, &ins,
+                                                     sizeof(*extent));
+                       BUG_ON(ret);
+                       extent = btrfs_item_ptr(
+                                   btrfs_buffer_leaf(path->nodes[0]),
+                                   path->slots[0],
+                                   struct btrfs_file_extent_item);
+                       btrfs_set_file_extent_disk_blocknr(extent,
+                                   btrfs_file_extent_disk_blocknr(&old));
+                       btrfs_set_file_extent_disk_num_blocks(extent,
+                                   btrfs_file_extent_disk_num_blocks(&old));
+
+                       btrfs_set_file_extent_offset(extent,
+                                   btrfs_file_extent_offset(&old) +
+                                   ((end - key.offset) >> inode->i_blkbits));
+                       WARN_ON(btrfs_file_extent_num_blocks(&old) <
+                               (end - key.offset) >> inode->i_blkbits);
+                       btrfs_set_file_extent_num_blocks(extent,
+                                   btrfs_file_extent_num_blocks(&old) -
+                                   ((end - key.offset) >> inode->i_blkbits));
+
+                       btrfs_set_file_extent_generation(extent,
+                                   btrfs_file_extent_generation(&old));
+printk("new bookend at offset %Lu, file_extent_offset %Lu, file_extent_num_blocks %Lu\n", end, btrfs_file_extent_offset(extent), btrfs_file_extent_num_blocks(extent));
+                       btrfs_mark_buffer_dirty(path->nodes[0]);
+                       ret = 0;
+                       goto out_nocsum;
+               }
+next_leaf:
+               if (slot >= btrfs_header_nritems(&leaf->header) - 1) {
+                       ret = btrfs_next_leaf(root, path);
+                       if (ret) {
+                               ret = 0;
+                               goto out;
+                       }
+               } else {
+                       path->slots[0]++;
+               }
+       }
+
+out:
+       ret = drop_csums(trans, root, inode, start, end);
+       BUG_ON(ret);
+
+out_nocsum:
+       btrfs_free_path(path);
+       return ret;
+}
+
+static int prepare_pages(struct btrfs_root *root,
                         struct file *file,
                         struct page **pages,
                         size_t num_pages,
@@ -1289,7 +1527,6 @@ static int prepare_pages(struct btrfs_trans_handle *trans,
        struct inode *inode = file->f_path.dentry->d_inode;
        int offset;
        int err = 0;
-       int ret;
        int this_write;
        struct buffer_head *bh;
        struct buffer_head *head;
@@ -1305,18 +1542,21 @@ static int prepare_pages(struct btrfs_trans_handle *trans,
                }
                offset = pos & (PAGE_CACHE_SIZE -1);
                this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
-               if (!PageUptodate(pages[i]) &&
-                  (pages[i]->index == first_index ||
-                   pages[i]->index == last_index) && pos < isize) {
+#if 0
+               if ((pages[i]->index == first_index ||
+                   pages[i]->index == last_index) && pos < isize &&
+                   !PageUptodate(pages[i])) {
                        ret = mpage_readpage(pages[i], btrfs_get_block);
                        BUG_ON(ret);
                        lock_page(pages[i]);
                }
+#endif
                create_empty_buffers(pages[i], root->fs_info->sb->s_blocksize,
                                     (1 << BH_Uptodate));
                head = page_buffers(pages[i]);
                bh = head;
                do {
+printk("mapping page %lu to block %Lu\n", pages[i]->index, alloc_extent_start);
                        err = btrfs_map_bh_to_logical(root, bh,
                                                      alloc_extent_start);
                        BUG_ON(err);
@@ -1351,7 +1591,7 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
        int ret = 0;
        struct inode *inode = file->f_path.dentry->d_inode;
        struct btrfs_root *root = BTRFS_I(inode)->root;
-       struct page *pages[1];
+       struct page *pages[8];
        unsigned long first_index;
        unsigned long last_index;
        u64 start_pos;
@@ -1359,6 +1599,7 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
        u64 alloc_extent_start;
        u64 orig_extent_start;
        struct btrfs_trans_handle *trans;
+       struct btrfs_key ins;
 
        if (file->f_flags & O_DIRECT)
                return -EINVAL;
@@ -1390,16 +1631,24 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
        trans = btrfs_start_transaction(root, 1);
        if (!trans) {
                err = -ENOMEM;
+               mutex_unlock(&root->fs_info->fs_mutex);
                goto out_unlock;
        }
-       ret = btrfs_alloc_file_extent(trans, root, inode->i_ino,
-                                     start_pos, num_blocks, 1,
-                                     &alloc_extent_start);
-       BUG_ON(ret);
-
+       if (start_pos < inode->i_size) {
+               ret = drop_extents(trans, root, inode,
+                                  start_pos,
+                                  (pos + count + root->blocksize -1) &
+                                  ~(root->blocksize - 1));
+       }
        orig_extent_start = start_pos;
-       ret = btrfs_end_transaction(trans, root);
+       ret = btrfs_alloc_extent(trans, root, num_blocks, 1,
+                                (u64)-1, &ins);
+       BUG_ON(ret);
+       ret = btrfs_insert_file_extent(trans, root, inode->i_ino,
+                                      start_pos, ins.objectid, ins.offset);
        BUG_ON(ret);
+       alloc_extent_start = ins.objectid;
+       ret = btrfs_end_transaction(trans, root);
        mutex_unlock(&root->fs_info->fs_mutex);
 
        while(count > 0) {
@@ -1407,16 +1656,21 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                size_t write_bytes = min(count, PAGE_CACHE_SIZE - offset);
                size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
                                        PAGE_CACHE_SHIFT;
-               ret = prepare_pages(NULL, root, file, pages, num_pages,
+printk("num_pages is %lu\n", num_pages);
+
+               memset(pages, 0, sizeof(pages));
+               ret = prepare_pages(root, file, pages, num_pages,
                                    pos, first_index, last_index,
                                    write_bytes, alloc_extent_start);
                BUG_ON(ret);
+
                /* FIXME blocks != pagesize */
                alloc_extent_start += num_pages;
                ret = btrfs_copy_from_user(pos, num_pages,
                                           write_bytes, pages, buf);
                BUG_ON(ret);
 
+printk("2num_pages is %lu\n", num_pages);
                ret = dirty_and_release_pages(NULL, root, file, pages,
                                              num_pages, orig_extent_start,
                                              pos, write_bytes);