| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.10 025/103] btrfs: prevent __btrfs_dump_space_info() to underflow its free space | Date | Mon, 27 Sep 2021 19:01:57 +0200 |
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From: Qu Wenruo <wqu@suse.com>
commit 0619b7901473c380abc05d45cf9c70bee0707db3 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- fs/btrfs/space-info.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/fs/btrfs/space-info.c +++ b/fs/btrfs/space-info.c @@ -417,9 +417,10 @@ static void __btrfs_dump_space_info(stru { 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",
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