linux-kernel - [PATCH 24/27] afs: Fix afs_statfs() to not let the values go below zero

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Message-ID: <159078977780.679399.6918426082550606601.stgit@warthog.procyon.org.uk>
Date:   Fri, 29 May 2020 23:02:57 +0100
From:   David Howells <dhowells@...hat.com>
To:     linux-afs@...ts.infradead.org
Cc:     dhowells@...hat.com, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 24/27] afs: Fix afs_statfs() to not let the values go below
 zero

Fix afs_statfs() so that the value for f_bavail and f_bfree don't go
"negative" if the number of blocks in use by a volume exceeds the max quota
for that volume.

Signed-off-by: David Howells <dhowells@...hat.com>
---

 fs/afs/super.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/afs/super.c b/fs/afs/super.c
index c77b11b31233..b552357b1d13 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -729,7 +729,10 @@ static void afs_get_volume_status_success(struct afs_operation *op)
 		buf->f_blocks = vs->part_max_blocks;
 	else
 		buf->f_blocks = vs->max_quota;
-	buf->f_bavail = buf->f_bfree = buf->f_blocks - vs->blocks_in_use;
+
+	if (buf->f_blocks > vs->blocks_in_use)
+		buf->f_bavail = buf->f_bfree =
+			buf->f_blocks - vs->blocks_in_use;
 }
 
 static const struct afs_operation_ops afs_get_volume_status_operation = {