From 58bfe2ccec5f9f137b41dd38f335290dcc13cd5c Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Mon, 18 Sep 2023 10:34:51 -0400 Subject: [PATCH] btrfs: properly report 0 avail for very full file systems A user reported some issues with smaller file systems that get very full. While investigating this issue I noticed that df wasn't showing 100% full, despite having 0 chunk space and having < 1MiB of available metadata space. This turns out to be an overflow issue, we're doing: total_available_metadata_space - SZ_4M < global_block_rsv_size to determine if there's not enough space to make metadata allocations, which overflows if total_available_metadata_space is < 4M. Fix this by checking to see if our available space is greater than the 4M threshold. This makes df properly report 100% usage on the file system. CC: stable@vger.kernel.org # 4.14+ Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index cffdd6f7f8e8..1a093ec0f7e3 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -2117,7 +2117,7 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf) * calculated f_bavail. */ if (!mixed && block_rsv->space_info->full && - total_free_meta - thresh < block_rsv->size) + (total_free_meta < thresh || total_free_meta - thresh < block_rsv->size)) buf->f_bavail = 0; buf->f_type = BTRFS_SUPER_MAGIC;