From: George Kennedy <george.kennedy@oracle.com>
Date: Wed, 15 Feb 2017 20:17:58 +0000 (-0500)
Subject: SPARC64: vds_blk_rw() does not handle drives with q->limits.chunk_sectors > 0
X-Git-Tag: v4.1.12-98.0.20170517_2143~37^2~2
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=782dd8bbc86912c26d3a5ae1bbdebbd54b460725;p=users%2Fjedix%2Flinux-maple.git

SPARC64: vds_blk_rw() does not handle drives with q->limits.chunk_sectors > 0

Drives with q->limits.chunk_sectors > 0 are not properly handled by
vds_blk_rw(). Drives such as NVME set chunk_sectors to indicate a performance
boundary (see call to blk_queue_chunk_sectors() in nvme_alloc_ns()). Currently,
when vds_blk_rw() calls bio_add_page() and the chunk_sectors boundary would be
crossed, bio_add_page() returns zero and vds_blk_rw() fails with -EIO.

The proposed fix now adds an additional check to vds_blk_rw() when
bio_add_page() returns zero that checks for bio->bi_iter.bi_size != 0. If
bi_size != 0, it indicates that a page or pages have been successfully added by
bio_add_page(). When this added condition has been hit, exit the for loop in
vds_blk_rw() and submit the outstanding IOs and continue.

Signed-off-by: George Kennedy <george.kennedy@oracle.com>
Reviewed-By: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Reviewed-By: Liam Merwick <Liam.Merwick@oracle.com>

Orabug: 25373818
Signed-off-by: Allen Pais <allen.pais@oracle.com>
---

diff --git a/drivers/block/vds/vds_blk.c b/drivers/block/vds/vds_blk.c
index 9cc1635f3dee9..e650294d45209 100644
--- a/drivers/block/vds/vds_blk.c
+++ b/drivers/block/vds/vds_blk.c
@@ -1,7 +1,7 @@
 /*
  * vds_blk.c: LDOM Virtual Disk Server.
  *
- * Copyright (C) 2014, 2016 Oracle. All rights reserved.
+ * Copyright (C) 2014, 2017 Oracle. All rights reserved.
  */
 
 #include "vds.h"
@@ -149,9 +149,19 @@ static int vds_blk_rw(struct vds_io *io)
 			       bio->bi_iter.bi_sector, bio->bi_iter.bi_size);
 
 			if (!rv) {
+				/*
+				 * A drive with chunk_sectors > 0 (i.e. NVME)
+				 * will result in rv = 0 when the chunk_sectors
+				 * boundary has been hit. Break here if page(s)
+				 * have already been added (bi_size != 0).
+				 * Submit the already added pages and continue.
+				 */
+				if (bio->bi_iter.bi_size != 0)
+					break;
 				vdsmsg(err,
-				       "bio_add_page: resid=%ld biolen=%ld\n",
-				       resid, biolen);
+				       "bio_add_page: resid=%ld biolen=%ld "
+				       "bi_sector=%ld\n",
+				       resid, biolen, bio->bi_iter.bi_sector);
 				err = -EIO;
 				break;
 			}