Since mixed block groups accounting isn't byte-accurate and f_bree is an
unsigned integer, it could overflow. Avoid this.
Signed-off-by: Luis de Bethencourt <lui...@osg.samsung.com>
Suggested-by: David Sterba <dste...@suse.com>
---
fs/btrfs/super.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index bdca79c..93376d0 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2101,6 +2101,11 @@ static int btrfs_statfs(struct dentry *dentry, struct
kstatfs *buf)
/* Account global block reserve as used, it's in logical size already */
spin_lock(&block_rsv->lock);
buf->f_bfree -= block_rsv->size >> bits;
+ /* Mixed block groups accounting is not byte-accurate, avoid overflow */
+ if (buf->f_bfree >= block_rsv->size >> bits)
+ buf->f_bfree -= block_rsv->size >> bits;
+ else
+ buf->f_bfree = 0;
spin_unlock(&block_rsv->lock);
buf->f_bavail = div_u64(total_free_data, factor);
--
2.5.3
