This is a note to let you know that I've just added the patch titled btrfs: prevent __btrfs_dump_space_info() to underflow its free space to the 5.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: btrfs-prevent-__btrfs_dump_space_info-to-underflow-its-free-space.patch and it can be found in the queue-5.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 0619b7901473c380abc05d45cf9c70bee0707db3 Mon Sep 17 00:00:00 2001 From: Qu Wenruo <wqu@xxxxxxxx> Date: Thu, 16 Sep 2021 20:43:29 +0800 Subject: btrfs: prevent __btrfs_dump_space_info() to underflow its free space From: Qu Wenruo <wqu@xxxxxxxx> 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@xxxxxxxxx> Link: https://lore.kernel.org/linux-btrfs/CAJtFHUSy4zgyhf-4d9T+KdJp9w=UgzC2A0V=VtmaeEpcGgm1-Q@xxxxxxxxxxxxxx/ CC: stable@xxxxxxxxxxxxxxx # 5.4+ Reviewed-by: Anand Jain <anand.jain@xxxxxxxxxx> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> Reviewed-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -414,9 +414,10 @@ 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 zone_unusable=%llu", Patches currently in stable-queue which might be from wqu@xxxxxxxx are queue-5.14/btrfs-prevent-__btrfs_dump_space_info-to-underflow-its-free-space.patch