From 23bc583f18eb8ffc28604a4ae42e2f7a55b31c3e Mon Sep 17 00:00:00 2001

From: Stefan Hajnoczi <stefanha@redhat.com>

Date: Thu, 5 Nov 2015 15:20:57 +0100

Subject: [PATCH 2/6] rbd: make qemu's cache setting override any ceph setting

Message-id: <1446736858-29005-2-git-send-email-stefanha@redhat.com>

Patchwork-id: 68293

O-Subject: [RHEL-7.2.z qemu-kvm PATCH 1/2] rbd: make qemu's cache setting override any ceph setting

Bugzilla: 1277248

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: Jeffrey Cody <jcody@redhat.com>

RH-Acked-by: Kevin Wolf <kwolf@redhat.com>

From: Josh Durgin <jdurgin@redhat.com>

To be safe, when cache=none is used ceph settings should not be able

to override it to turn on caching. This was previously possible with

rbd_cache=true in the rbd device configuration or a ceph configuration

file. Similarly, rbd settings could have turned off caching when qemu

requested it, although this would just be a performance problem.

Fix this by changing rbd's cache setting to match qemu after all other

ceph settings have been applied.

Signed-off-by: Josh Durgin <jdurgin@redhat.com>

Reviewed-by: Jeff Cody <jcody@redhat.com>

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

(cherry picked from commit 99a3c89d5d538dc6c360e35dffb797cfe06e9cda)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

Conflicts:

	block/rbd.c - downstream doesn't use Error **errp

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

---

 block/rbd.c | 26 +++++++++++++-------------

 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/block/rbd.c b/block/rbd.c

index 4eea455..11a39ac 100644

--- a/block/rbd.c

+++ b/block/rbd.c

@@ -501,19 +501,6 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags,

         s->snap = g_strdup(snap_buf);

     }

-    /*

-     * Fallback to more conservative semantics if setting cache

-     * options fails. Ignore errors from setting rbd_cache because the

-     * only possible error is that the option does not exist, and

-     * librbd defaults to no caching. If write through caching cannot

-     * be set up, fall back to no caching.

-     */

-    if (flags & BDRV_O_NOCACHE) {

-        rados_conf_set(s->cluster, "rbd_cache", "false");

-    } else {

-        rados_conf_set(s->cluster, "rbd_cache", "true");

-    }

-

     if (strstr(conf, "conf=") == NULL) {

         /* try default location, but ignore failure */

         rados_conf_read_file(s->cluster, NULL);

@@ -527,6 +514,19 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags,

         }

     }

+    /*

+     * Fallback to more conservative semantics if setting cache

+     * options fails. Ignore errors from setting rbd_cache because the

+     * only possible error is that the option does not exist, and

+     * librbd defaults to no caching. If write through caching cannot

+     * be set up, fall back to no caching.

+     */

+    if (flags & BDRV_O_NOCACHE) {

+        rados_conf_set(s->cluster, "rbd_cache", "false");

+    } else {

+        rados_conf_set(s->cluster, "rbd_cache", "true");

+    }

+

     r = rados_connect(s->cluster);

     if (r < 0) {

         error_report("error connecting");

-- 

1.8.3.1