From 0619b7901473c380abc05d45cf9c70bee0707db3 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Thu, 16 Sep 2021 20:43:29 +0800 Subject: [PATCH] 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 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 Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/space-info.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c index 5ada02e0e629..aa5be0b24987 100644 --- a/fs/btrfs/space-info.c +++ b/fs/btrfs/space-info.c @@ -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",