rbd: require stable pages if message data CRCs are enabled

Ronny Hegewald · idryomov · commit bae818ee1577 · 2015-10-30T19:25:02.000+01:00
rbd requires stable pages, as it performs a crc of the page data before they are send to the OSDs. But since kernel 3.9 (patch 1d1d1a7 "mm: only enforce stable page writes if the backing device requires it") it is not assumed anymore that block devices require stable pages. This patch sets the necessary flag to get stable pages back for rbd. In a ceph installation that provides multiple ext4 formatted rbd devices "bad crc" messages appeared regularly (ca 1 message every 1-2 minutes on every OSD that provided the data for the rbd) in the OSD-logs before this patch. After this patch this messages are pretty much gone (only ca 1-2 / month / OSD). Cc: stable@vger.kernel.org # 3.9+, needs backporting Signed-off-by: Ronny Hegewald <Ronny.Hegewald@online.de> [idryomov@gmail.com: require stable pages only in crc case, changelog] Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
@@ -3780,6 +3780,9 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
 	blk_queue_max_discard_sectors(q, segment_size / SECTOR_SIZE);
 	q->limits.discard_zeroes_data = 1;
 
+	if (!ceph_test_opt(rbd_dev->rbd_client->client, NOCRC))
+		q->backing_dev_info.capabilities |= BDI_CAP_STABLE_WRITES;
+
 	disk->queue = q;
 
 	q->queuedata = rbd_dev;
