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btrfs: prevent __btrfs_dump_space_info() to underflow its free space 

It's not uncommon where __btrfs_dump_space_info() gets called
under over-commit situations.

In that case free space would underflow as total allocated space is not
enough to handle all the over-committed space.

Such underflow values can sometimes cause confusion for users enabled
enospc_debug mount option, and takes some seconds for developers to
convert the underflow value to signed result.

Just output the free space as s64 to avoid such problem.

Reported-by: Eli V <eliventer@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CAJtFHUSy4zgyhf-4d9T+KdJp9w=UgzC2A0V=VtmaeEpcGgm1-Q@mail.gmail.com/
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2021-09-16 20:43:29 +08:00 committed by David Sterba
parent 6b225baaba
commit 0619b79014
1 changed files with 3 additions and 2 deletions
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5
fs/btrfs/space-info.c
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@ -414,9 +414,10 @@ static void __btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
{
lockdep_assert_held(&info->lock);
btrfs_info(fs_info, "space_info %llu has %llu free, is %sfull",
/* The free space could be negative in case of overcommit */
btrfs_info(fs_info, "space_info %llu has %lld free, is %sfull",
info->flags,
info->total_bytes - btrfs_space_info_used(info, true),
(s64)(info->total_bytes - btrfs_space_info_used(info, true)),
info->full ? "" : "not ");
btrfs_info(fs_info,
"space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu zone_unusable=%llu",