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Btrfs: fix send file hole detection leading to data corruption

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There was a case where file hole detection was incorrect and it would
cause an incremental send to override a section of a file with zeroes.

This happened in the case where between the last leaf we processed which
contained a file extent item for our current inode and the leaf we're
currently are at (and has a file extent item for our current inode) there
are only leafs containing exclusively file extent items for our current
inode, and none of them was updated since the previous send operation.
The file hole detection code would incorrectly consider the file range
covered by these leafs as a hole.

A test case for xfstests follows soon.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Filipe David Borba Manana 2014-01-28 01:38:06 +00:00 committed by Chris Mason
parent bca1a29003
commit bf54f412f0
1 changed files with 15 additions and 0 deletions
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15
fs/btrfs/send.c
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@ -4489,6 +4489,21 @@ static int maybe_send_hole(struct send_ctx *sctx, struct btrfs_path *path,
extent_end = key->offset +
btrfs_file_extent_num_bytes(path->nodes[0], fi);
}
if (path->slots[0] == 0 &&
sctx->cur_inode_last_extent < key->offset) {
/*
* We might have skipped entire leafs that contained only
* file extent items for our current inode. These leafs have
* a generation number smaller (older) than the one in the
* current leaf and the leaf our last extent came from, and
* are located between these 2 leafs.
*/
ret = get_last_extent(sctx, key->offset - 1);
if (ret)
return ret;
}
if (sctx->cur_inode_last_extent < key->offset)
ret = send_hole(sctx, key->offset);
sctx->cur_inode_last_extent = extent_end;