packaging: Enable LTO and set visibility to hidden
[platform/upstream/btrfs-progs.git] / file-item.c
index 4cbc2a5..7b0ff35 100644 (file)
 #include "transaction.h"
 #include "print-tree.h"
 #include "crc32c.h"
+#include "internal.h"
 
-#define MAX_CSUM_ITEMS(r) ((((BTRFS_LEAF_DATA_SIZE(r) - \
+#define MAX_CSUM_ITEMS(r, size) ((((BTRFS_LEAF_DATA_SIZE(r->fs_info) - \
                               sizeof(struct btrfs_item) * 2) / \
-                              BTRFS_CRC32_SIZE) - 1))
-int btrfs_create_file(struct btrfs_trans_handle *trans,
-                     struct btrfs_root *root, u64 dirid, u64 *objectid)
-{
-       return 0;
-}
-
+                              size) - 1))
 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
                             struct btrfs_root *root,
                             u64 objectid, u64 pos, u64 offset,
                             u64 disk_num_bytes, u64 num_bytes)
 {
        int ret = 0;
+       int is_hole = 0;
        struct btrfs_file_extent_item *item;
        struct btrfs_key file_key;
        struct btrfs_path *path;
        struct extent_buffer *leaf;
 
+       if (offset == 0)
+               is_hole = 1;
+       /* For NO_HOLES, we don't insert hole file extent */
+       if (btrfs_fs_incompat(root->fs_info, NO_HOLES) && is_hole)
+               return 0;
+
+       /* For hole, its disk_bytenr and disk_num_bytes must be 0 */
+       if (is_hole)
+               disk_num_bytes = 0;
+
        path = btrfs_alloc_path();
-       BUG_ON(!path);
+       if (!path)
+               return -ENOMEM;
+
        file_key.objectid = objectid;
        file_key.offset = pos;
-       btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
+       file_key.type = BTRFS_EXTENT_DATA_KEY;
 
        ret = btrfs_insert_empty_item(trans, root, path, &file_key,
                                      sizeof(*item));
@@ -64,8 +72,12 @@ int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
        btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
        btrfs_set_file_extent_offset(leaf, item, 0);
        btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
+       btrfs_set_file_extent_ram_bytes(leaf, item, num_bytes);
        btrfs_set_file_extent_generation(leaf, item, trans->transid);
        btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
+       btrfs_set_file_extent_compression(leaf, item, 0);
+       btrfs_set_file_extent_encryption(leaf, item, 0);
+       btrfs_set_file_extent_other_encoding(leaf, item, 0);
        btrfs_mark_buffer_dirty(leaf);
 out:
        btrfs_free_path(path);
@@ -74,7 +86,7 @@ out:
 
 int btrfs_insert_inline_extent(struct btrfs_trans_handle *trans,
                               struct btrfs_root *root, u64 objectid,
-                              u64 offset, char *buffer, size_t size)
+                              u64 offset, const char *buffer, size_t size)
 {
        struct btrfs_key key;
        struct btrfs_path *path;
@@ -91,97 +103,25 @@ int btrfs_insert_inline_extent(struct btrfs_trans_handle *trans,
 
        key.objectid = objectid;
        key.offset = offset;
-       btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
+       key.type = BTRFS_EXTENT_DATA_KEY;
 
-       ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
-       if (ret < 0) {
+       datasize = btrfs_file_extent_calc_inline_size(size);
+       ret = btrfs_insert_empty_item(trans, root, path, &key, datasize);
+       if (ret) {
                err = ret;
                goto fail;
        }
-       if (ret == 1) {
-               struct btrfs_key found_key;
-
-               if (path->slots[0] == 0)
-                       goto insert;
 
-               path->slots[0]--;
-               leaf = path->nodes[0];
-               btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
-
-               if (found_key.objectid != objectid)
-                       goto insert;
-
-               if (found_key.type != BTRFS_EXTENT_DATA_KEY)
-                       goto insert;
-               ei = btrfs_item_ptr(leaf, path->slots[0],
-                                   struct btrfs_file_extent_item);
-
-               if (btrfs_file_extent_type(leaf, ei) !=
-                   BTRFS_FILE_EXTENT_INLINE) {
-                       goto insert;
-               }
-               btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
-               ret = 0;
-       }
-       if (ret == 0) {
-               u32 found_size;
-               u64 found_end;
+       leaf = path->nodes[0];
+       ei = btrfs_item_ptr(leaf, path->slots[0],
+                           struct btrfs_file_extent_item);
+       btrfs_set_file_extent_generation(leaf, ei, trans->transid);
+       btrfs_set_file_extent_type(leaf, ei, BTRFS_FILE_EXTENT_INLINE);
+       btrfs_set_file_extent_ram_bytes(leaf, ei, size);
+       btrfs_set_file_extent_compression(leaf, ei, 0);
+       btrfs_set_file_extent_encryption(leaf, ei, 0);
+       btrfs_set_file_extent_other_encoding(leaf, ei, 0);
 
-               leaf = path->nodes[0];
-               ei = btrfs_item_ptr(leaf, path->slots[0],
-                                   struct btrfs_file_extent_item);
-
-               if (btrfs_file_extent_type(leaf, ei) !=
-                   BTRFS_FILE_EXTENT_INLINE) {
-                       err = ret;
-                       btrfs_print_leaf(root, leaf);
-                       printk("found wasn't inline offset %llu inode %llu\n",
-                              (unsigned long long)offset,
-                              (unsigned long long)objectid);
-                       goto fail;
-               }
-               found_size = btrfs_file_extent_inline_len(leaf,
-                                         btrfs_item_nr(leaf, path->slots[0]));
-               found_end = key.offset + found_size;
-
-               if (found_end < offset + size) {
-                       btrfs_release_path(root, path);
-                       ret = btrfs_search_slot(trans, root, &key, path,
-                                               offset + size - found_end, 1);
-                       BUG_ON(ret != 0);
-
-                       ret = btrfs_extend_item(trans, root, path,
-                                               offset + size - found_end);
-                       if (ret) {
-                               err = ret;
-                               goto fail;
-                       }
-                       leaf = path->nodes[0];
-                       ei = btrfs_item_ptr(leaf, path->slots[0],
-                                           struct btrfs_file_extent_item);
-               }
-               if (found_end < offset) {
-                       ptr = btrfs_file_extent_inline_start(ei) + found_size;
-                       memset_extent_buffer(leaf, 0, ptr, offset - found_end);
-               }
-       } else {
-insert:
-               btrfs_release_path(root, path);
-               datasize = offset + size - key.offset;
-               datasize = btrfs_file_extent_calc_inline_size(datasize);
-               ret = btrfs_insert_empty_item(trans, root, path, &key,
-                                             datasize);
-               if (ret) {
-                       err = ret;
-                       printk("got bad ret %d\n", ret);
-                       goto fail;
-               }
-               leaf = path->nodes[0];
-               ei = btrfs_item_ptr(leaf, path->slots[0],
-                                   struct btrfs_file_extent_item);
-               btrfs_set_file_extent_generation(leaf, ei, trans->transid);
-               btrfs_set_file_extent_type(leaf, ei, BTRFS_FILE_EXTENT_INLINE);
-       }
        ptr = btrfs_file_extent_inline_start(ei) + offset - key.offset;
        write_extent_buffer(leaf, buffer, ptr, size);
        btrfs_mark_buffer_dirty(leaf);
@@ -190,10 +130,11 @@ fail:
        return err;
 }
 
-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)
+static struct btrfs_csum_item *
+btrfs_lookup_csum(struct btrfs_trans_handle *trans,
+                 struct btrfs_root *root,
+                 struct btrfs_path *path,
+                 u64 bytenr, int cow)
 {
        int ret;
        struct btrfs_key file_key;
@@ -201,11 +142,13 @@ struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
        struct btrfs_csum_item *item;
        struct extent_buffer *leaf;
        u64 csum_offset = 0;
+       u16 csum_size =
+               btrfs_super_csum_size(root->fs_info->super_copy);
        int csums_in_item;
 
-       file_key.objectid = objectid;
-       file_key.offset = offset;
-       btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+       file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+       file_key.offset = bytenr;
+       file_key.type = BTRFS_EXTENT_CSUM_KEY;
        ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
        if (ret < 0)
                goto fail;
@@ -216,13 +159,13 @@ struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
                        goto fail;
                path->slots[0]--;
                btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
-               if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
-                   found_key.objectid != objectid) {
+               if (found_key.type != BTRFS_EXTENT_CSUM_KEY)
                        goto fail;
-               }
-               csum_offset = (offset - found_key.offset) >> root->sectorsize;
+
+               csum_offset = (bytenr - found_key.offset) /
+                               root->fs_info->sectorsize;
                csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
-               csums_in_item /= BTRFS_CRC32_SIZE;
+               csums_in_item /= csum_size;
 
                if (csum_offset >= csums_in_item) {
                        ret = -EFBIG;
@@ -231,7 +174,7 @@ struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
        }
        item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
        item = (struct btrfs_csum_item *)((unsigned char *)item +
-                                         csum_offset * BTRFS_CRC32_SIZE);
+                                         csum_offset * csum_size);
        return item;
 fail:
        if (ret > 0)
@@ -239,31 +182,11 @@ fail:
        return ERR_PTR(ret);
 }
 
-
-int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
-                            struct btrfs_root *root,
-                            struct btrfs_path *path, u64 objectid,
-                            u64 offset, int mod)
-{
-       int ret;
-       struct btrfs_key file_key;
-       int ins_len = mod < 0 ? -1 : 0;
-       int cow = mod != 0;
-
-       file_key.objectid = objectid;
-       file_key.offset = offset;
-       btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
-       ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
-       return ret;
-}
-
 int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
-                         struct btrfs_root *root,
-                         struct btrfs_inode_item *inode,
-                         u64 objectid, u64 offset,
-                         char *data, size_t len)
+                         struct btrfs_root *root, u64 alloc_end,
+                         u64 bytenr, char *data, size_t len)
 {
-       int ret;
+       int ret = 0;
        struct btrfs_key file_key;
        struct btrfs_key found_key;
        u64 next_offset = (u64)-1;
@@ -273,19 +196,24 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
        struct extent_buffer *leaf = NULL;
        u64 csum_offset;
        u32 csum_result = ~(u32)0;
+       u32 sectorsize = root->fs_info->sectorsize;
        u32 nritems;
        u32 ins_size;
+       u16 csum_size =
+               btrfs_super_csum_size(root->fs_info->super_copy);
 
        path = btrfs_alloc_path();
-       BUG_ON(!path);
+       if (!path)
+               return -ENOMEM;
 
-       file_key.objectid = objectid;
-       file_key.offset = offset;
-       btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+       file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+       file_key.offset = bytenr;
+       file_key.type = BTRFS_EXTENT_CSUM_KEY;
 
-       item = btrfs_lookup_csum(trans, root, path, objectid, offset, 1);
+       item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
        if (!IS_ERR(item)) {
                leaf = path->nodes[0];
+               ret = 0;
                goto found;
        }
        ret = PTR_ERR(item);
@@ -294,7 +222,7 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
                /* we found one, but it isn't big enough yet */
                leaf = path->nodes[0];
                item_size = btrfs_item_size_nr(leaf, path->slots[0]);
-               if ((item_size / BTRFS_CRC32_SIZE) >= MAX_CSUM_ITEMS(root)) {
+               if ((item_size / csum_size) >= MAX_CSUM_ITEMS(root, csum_size)) {
                        /* already at max size, make a new one */
                        goto insert;
                }
@@ -311,8 +239,8 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
                        slot = 0;
                }
                btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
-               if (found_key.objectid != objectid ||
-                   found_key.type != BTRFS_CSUM_ITEM_KEY) {
+               if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
+                   found_key.type != BTRFS_EXTENT_CSUM_KEY) {
                        found_next = 1;
                        goto insert;
                }
@@ -325,9 +253,9 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
         * at this point, we know the tree has an item, but it isn't big
         * enough yet to put our csum in.  Grow it
         */
-       btrfs_release_path(root, path);
+       btrfs_release_path(path);
        ret = btrfs_search_slot(trans, root, &file_key, path,
-                               BTRFS_CRC32_SIZE, 1);
+                               csum_size, 1);
        if (ret < 0)
                goto fail;
        if (ret == 0) {
@@ -339,35 +267,35 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
        path->slots[0]--;
        leaf = path->nodes[0];
        btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
-       csum_offset = (offset - found_key.offset) / root->sectorsize;
-       if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
-           found_key.objectid != objectid ||
-           csum_offset >= MAX_CSUM_ITEMS(root)) {
+       csum_offset = (file_key.offset - found_key.offset) / sectorsize;
+       if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
+           found_key.type != BTRFS_EXTENT_CSUM_KEY ||
+           csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
                goto insert;
        }
        if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
-           BTRFS_CRC32_SIZE) {
-               u32 diff = (csum_offset + 1) * BTRFS_CRC32_SIZE;
+           csum_size) {
+               u32 diff = (csum_offset + 1) * csum_size;
                diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
-               if (diff != BTRFS_CRC32_SIZE)
+               if (diff != csum_size)
                        goto insert;
-               ret = btrfs_extend_item(trans, root, path, diff);
+               ret = btrfs_extend_item(root, path, diff);
                BUG_ON(ret);
                goto csum;
        }
 
 insert:
-       btrfs_release_path(root, path);
+       btrfs_release_path(path);
        csum_offset = 0;
        if (found_next) {
-               u64 tmp = min(btrfs_stack_inode_size(inode), next_offset);
-               tmp -= offset & ~((u64)root->sectorsize -1);
-               tmp /= root->sectorsize;
+               u64 tmp = min(alloc_end, next_offset);
+               tmp -= file_key.offset;
+               tmp /= sectorsize;
                tmp = max((u64)1, tmp);
-               tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root));
-               ins_size = BTRFS_CRC32_SIZE * tmp;
+               tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
+               ins_size = csum_size * tmp;
        } else {
-               ins_size = BTRFS_CRC32_SIZE;
+               ins_size = csum_size;
        }
        ret = btrfs_insert_empty_item(trans, root, path, &file_key,
                                      ins_size);
@@ -382,46 +310,192 @@ csum:
        item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
        ret = 0;
        item = (struct btrfs_csum_item *)((unsigned char *)item +
-                                         csum_offset * BTRFS_CRC32_SIZE);
+                                         csum_offset * csum_size);
 found:
-       csum_result = btrfs_csum_data(root, data, csum_result, len);
-       btrfs_csum_final(csum_result, (char *)&csum_result);
+       csum_result = btrfs_csum_data(data, csum_result, len);
+       btrfs_csum_final(csum_result, (u8 *)&csum_result);
        if (csum_result == 0) {
-               printk("csum result is 0 for inode %llu offset %llu\n",
-                      (unsigned long long)objectid,
-                      (unsigned long long)offset);
+               printk("csum result is 0 for block %llu\n",
+                      (unsigned long long)bytenr);
        }
 
        write_extent_buffer(leaf, &csum_result, (unsigned long)item,
-                           BTRFS_CRC32_SIZE);
+                           csum_size);
        btrfs_mark_buffer_dirty(path->nodes[0]);
 fail:
-       btrfs_release_path(root, path);
        btrfs_free_path(path);
        return ret;
 }
 
-int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
-                       struct btrfs_root *root, struct btrfs_path *path,
-                       u64 isize)
+/*
+ * helper function for csum removal, this expects the
+ * key to describe the csum pointed to by the path, and it expects
+ * the csum to overlap the range [bytenr, len]
+ *
+ * The csum should not be entirely contained in the range and the
+ * range should not be entirely contained in the csum.
+ *
+ * This calls btrfs_truncate_item with the correct args based on the
+ * overlap, and fixes up the key as required.
+ */
+static noinline int truncate_one_csum(struct btrfs_root *root,
+                                     struct btrfs_path *path,
+                                     struct btrfs_key *key,
+                                     u64 bytenr, u64 len)
 {
+       struct extent_buffer *leaf;
+       u16 csum_size =
+               btrfs_super_csum_size(root->fs_info->super_copy);
+       u64 csum_end;
+       u64 end_byte = bytenr + len;
+       u32 blocksize = root->fs_info->sectorsize;
+       int ret;
+
+       leaf = path->nodes[0];
+       csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
+       csum_end *= root->fs_info->sectorsize;
+       csum_end += key->offset;
+
+       if (key->offset < bytenr && csum_end <= end_byte) {
+               /*
+                *         [ bytenr - len ]
+                *         [   ]
+                *   [csum     ]
+                *   A simple truncate off the end of the item
+                */
+               u32 new_size = (bytenr - key->offset) / blocksize;
+               new_size *= csum_size;
+               ret = btrfs_truncate_item(root, path, new_size, 1);
+               BUG_ON(ret);
+       } else if (key->offset >= bytenr && csum_end > end_byte &&
+                  end_byte > key->offset) {
+               /*
+                *         [ bytenr - len ]
+                *                 [ ]
+                *                 [csum     ]
+                * we need to truncate from the beginning of the csum
+                */
+               u32 new_size = (csum_end - end_byte) / blocksize;
+               new_size *= csum_size;
+
+               ret = btrfs_truncate_item(root, path, new_size, 0);
+               BUG_ON(ret);
+
+               key->offset = end_byte;
+               ret = btrfs_set_item_key_safe(root, path, key);
+               BUG_ON(ret);
+       } else {
+               BUG();
+       }
+       return 0;
+}
+
+/*
+ * deletes the csum items from the csum tree for a given
+ * range of bytes.
+ */
+int btrfs_del_csums(struct btrfs_trans_handle *trans,
+                   struct btrfs_root *root, u64 bytenr, u64 len)
+{
+       struct btrfs_path *path;
        struct btrfs_key key;
-       struct extent_buffer *leaf = path->nodes[0];
-       int slot = path->slots[0];
+       u64 end_byte = bytenr + len;
+       u64 csum_end;
+       struct extent_buffer *leaf;
        int ret;
-       u32 new_item_size;
-       u64 new_item_span;
-       u64 blocks;
+       u16 csum_size =
+               btrfs_super_csum_size(root->fs_info->super_copy);
+       int blocksize = root->fs_info->sectorsize;
 
-       btrfs_item_key_to_cpu(leaf, &key, slot);
-       if (isize <= key.offset)
-               return 0;
-       new_item_span = isize - key.offset;
-       blocks = (new_item_span + root->sectorsize - 1) / root->sectorsize;
-       new_item_size = blocks * BTRFS_CRC32_SIZE;
-       if (new_item_size >= btrfs_item_size_nr(leaf, slot))
-               return 0;
-       ret = btrfs_truncate_item(trans, root, path, new_item_size, 1);
-       BUG_ON(ret);
-       return ret;
+       root = root->fs_info->csum_root;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       while (1) {
+               key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+               key.offset = end_byte - 1;
+               key.type = BTRFS_EXTENT_CSUM_KEY;
+
+               ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+               if (ret > 0) {
+                       if (path->slots[0] == 0)
+                               goto out;
+                       path->slots[0]--;
+               }
+               leaf = path->nodes[0];
+               btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+
+               if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
+                   key.type != BTRFS_EXTENT_CSUM_KEY) {
+                       break;
+               }
+
+               if (key.offset >= end_byte)
+                       break;
+
+               csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
+               csum_end *= blocksize;
+               csum_end += key.offset;
+
+               /* this csum ends before we start, we're done */
+               if (csum_end <= bytenr)
+                       break;
+
+               /* delete the entire item, it is inside our range */
+               if (key.offset >= bytenr && csum_end <= end_byte) {
+                       ret = btrfs_del_item(trans, root, path);
+                       BUG_ON(ret);
+               } else if (key.offset < bytenr && csum_end > end_byte) {
+                       unsigned long offset;
+                       unsigned long shift_len;
+                       unsigned long item_offset;
+                       /*
+                        *        [ bytenr - len ]
+                        *     [csum                ]
+                        *
+                        * Our bytes are in the middle of the csum,
+                        * we need to split this item and insert a new one.
+                        *
+                        * But we can't drop the path because the
+                        * csum could change, get removed, extended etc.
+                        *
+                        * The trick here is the max size of a csum item leaves
+                        * enough room in the tree block for a single
+                        * item header.  So, we split the item in place,
+                        * adding a new header pointing to the existing
+                        * bytes.  Then we loop around again and we have
+                        * a nicely formed csum item that we can neatly
+                        * truncate.
+                        */
+                       offset = (bytenr - key.offset) / blocksize;
+                       offset *= csum_size;
+
+                       shift_len = (len / blocksize) * csum_size;
+
+                       item_offset = btrfs_item_ptr_offset(leaf,
+                                                           path->slots[0]);
+
+                       memset_extent_buffer(leaf, 0, item_offset + offset,
+                                            shift_len);
+                       key.offset = bytenr;
+
+                       /*
+                        * btrfs_split_item returns -EAGAIN when the
+                        * item changed size or key
+                        */
+                       ret = btrfs_split_item(trans, root, path, &key, offset);
+                       BUG_ON(ret && ret != -EAGAIN);
+
+                       key.offset = end_byte - 1;
+               } else {
+                       ret = truncate_one_csum(root, path, &key, bytenr, len);
+                       BUG_ON(ret);
+               }
+               btrfs_release_path(path);
+       }
+out:
+       btrfs_free_path(path);
+       return 0;
 }