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Btrfs: fix trim 0 bytes after a device delete

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A user reported a bug of btrfs's trim, that is we will trim 0 bytes
after a device delete.

The reproducer:

$ mkfs.btrfs disk1
$ mkfs.btrfs disk2
$ mount disk1 /mnt
$ fstrim -v /mnt
$ btrfs device add disk2 /mnt
$ btrfs device del disk1 /mnt
$ fstrim -v /mnt

This is because after we delete the device, the block group may start from
a non-zero place, which will confuse trim to discard nothing.

Reported-by: Lutz Euler <lutz.euler@freenet.de>
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
This commit is contained in:
Liu Bo 2012-02-09 18:17:41 +08:00 committed by David Sterba
parent 6af021d8fc
commit 2cac13e41b
1 changed files with 8 additions and 1 deletions
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9
fs/btrfs/extent-tree.c
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@ -7886,9 +7886,16 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
u64 start;
u64 end;
u64 trimmed = 0;
u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
int ret = 0;
cache = btrfs_lookup_block_group(fs_info, range->start);
/*
* try to trim all FS space, our block group may start from non-zero.
*/
if (range->len == total_bytes)
cache = btrfs_lookup_first_block_group(fs_info, range->start);
else
cache = btrfs_lookup_block_group(fs_info, range->start);
while (cache) {
if (cache->key.objectid >= (range->start + range->len)) {