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Btrfs: Fix race in btrfs_mark_extent_written
When extent needs to be split, btrfs_mark_extent_written truncates the extent first, then inserts a new extent and increases the reference count. The race happens if someone else deletes the old extent before the new extent is inserted. The fix here is increase the reference count in advance. This race is similar to the race in btrfs_drop_extents that was recently fixed. Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
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parent
2b82032c34
commit
c36047d729
1 changed files with 14 additions and 4 deletions
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@ -746,6 +746,7 @@ int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
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u64 other_end;
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u64 split = start;
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u64 locked_end = end;
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u64 orig_parent;
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int extent_type;
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int split_end = 1;
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int ret;
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@ -890,6 +891,12 @@ int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
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}
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btrfs_mark_buffer_dirty(leaf);
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orig_parent = leaf->start;
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ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes,
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orig_parent, root->root_key.objectid,
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trans->transid, inode->i_ino);
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BUG_ON(ret);
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btrfs_release_path(root, path);
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key.offset = start;
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@ -910,10 +917,13 @@ int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
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btrfs_set_file_extent_encryption(leaf, fi, 0);
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btrfs_set_file_extent_other_encoding(leaf, fi, 0);
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ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes,
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leaf->start, root->root_key.objectid,
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trans->transid, inode->i_ino);
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BUG_ON(ret);
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if (orig_parent != leaf->start) {
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ret = btrfs_update_extent_ref(trans, root, bytenr,
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orig_parent, leaf->start,
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root->root_key.objectid,
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trans->transid, inode->i_ino);
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BUG_ON(ret);
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}
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done:
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btrfs_mark_buffer_dirty(leaf);
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btrfs_release_path(root, path);
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