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[Qemu-devel] [PATCH] rbd: hook up cache options
From: |
Josh Durgin |
Subject: |
[Qemu-devel] [PATCH] rbd: hook up cache options |
Date: |
Thu, 17 May 2012 13:42:29 -0700 |
Writeback caching was added in Ceph 0.46, and writethrough will be in
0.47. These are controlled by general config options, so there's no
need to check for librbd version.
Signed-off-by: Josh Durgin <address@hidden>
---
block/rbd.c | 19 +++++++++++++++++++
1 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/block/rbd.c b/block/rbd.c
index 1280d66..eebc334 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -476,6 +476,25 @@ static int qemu_rbd_open(BlockDriverState *bs, const char
*filename, 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 (!(flags & BDRV_O_CACHE_WB)) {
+ r = rados_conf_set(s->cluster, "rbd_cache_max_dirty", "0");
+ if (r < 0) {
+ rados_conf_set(s->cluster, "rbd_cache", "false");
+ }
+ }
+ }
+
if (strstr(conf, "conf=") == NULL) {
/* try default location, but ignore failure */
rados_conf_read_file(s->cluster, NULL);
--
1.7.5.4
- [Qemu-devel] [PATCH] rbd: hook up cache options,
Josh Durgin <=