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| author | Liu Bo <bo.li.liu@oracle.com> | 2013-07-01 22:13:26 +0800 |
|---|---|---|
| committer | Chris Mason <chris.mason@fusionio.com> | 2013-08-09 19:29:17 -0400 |
| commit | e68afa49aec5f0851e550ee1de48fcc3a9bf5ef7 (patch) | |
| tree | 7588f986736b53f7d6e3117a5c3afdff1f638e13 | |
| parent | 7cddc193924ef6ce679ef0977e01e96d0aedfd1d (diff) | |
| download | linux-e68afa49aec5f0851e550ee1de48fcc3a9bf5ef7.tar.bz2 | |
Btrfs: fix a bug of snapshot-aware defrag to make it work on partial extents
For partial extents, snapshot-aware defrag does not work as expected,
since
a) we use the wrong logical offset to search for parents, which should be
disk_bytenr + extent_offset, not just disk_bytenr,
b) 'offset' returned by the backref walking just refers to key.offset, not
the 'offset' stored in btrfs_extent_data_ref which is
(key.offset - extent_offset).
The reproducer:
$ mkfs.btrfs sda
$ mount sda /mnt
$ btrfs sub create /mnt/sub
$ for i in `seq 5 -1 1`; do dd if=/dev/zero of=/mnt/sub/foo bs=5k count=1 seek=$i conv=notrunc oflag=sync; done
$ btrfs sub snap /mnt/sub /mnt/snap1
$ btrfs sub snap /mnt/sub /mnt/snap2
$ sync; btrfs filesystem defrag /mnt/sub/foo;
$ umount /mnt
$ btrfs-debug-tree sda (Here we can check whether the defrag operation is snapshot-awared.
This addresses the above two problems.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
| -rw-r--r-- | fs/btrfs/inode.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 0fd7647c8932..c72033ee6017 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -2166,16 +2166,23 @@ static noinline int record_one_backref(u64 inum, u64 offset, u64 root_id, if (btrfs_file_extent_disk_bytenr(leaf, extent) != old->bytenr) continue; - extent_offset = btrfs_file_extent_offset(leaf, extent); - if (key.offset - extent_offset != offset) + /* + * 'offset' refers to the exact key.offset, + * NOT the 'offset' field in btrfs_extent_data_ref, ie. + * (key.offset - extent_offset). + */ + if (key.offset != offset) continue; + extent_offset = btrfs_file_extent_offset(leaf, extent); num_bytes = btrfs_file_extent_num_bytes(leaf, extent); + if (extent_offset >= old->extent_offset + old->offset + old->len || extent_offset + num_bytes <= old->extent_offset + old->offset) continue; + ret = 0; break; } @@ -2187,7 +2194,7 @@ static noinline int record_one_backref(u64 inum, u64 offset, u64 root_id, backref->root_id = root_id; backref->inum = inum; - backref->file_pos = offset + extent_offset; + backref->file_pos = offset; backref->num_bytes = num_bytes; backref->extent_offset = extent_offset; backref->generation = btrfs_file_extent_generation(leaf, extent); @@ -2210,7 +2217,8 @@ static noinline bool record_extent_backrefs(struct btrfs_path *path, new->path = path; list_for_each_entry_safe(old, tmp, &new->head, list) { - ret = iterate_inodes_from_logical(old->bytenr, fs_info, + ret = iterate_inodes_from_logical(old->bytenr + + old->extent_offset, fs_info, path, record_one_backref, old); BUG_ON(ret < 0 && ret != -ENOENT); |