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authorJosh Durgin <josh.durgin@inktank.com>2012-05-17 13:42:29 -0700
committerKevin Wolf <kwolf@redhat.com>2012-06-15 14:03:42 +0200
commitb11f38fcdf837c6ba1d4287b1c685eb3ae5351a8 (patch)
treee4b8bc9573bd38b7ee5a842cac01c6fc955031e6 /block
parent166acf546f476d3594a1c1746dc265f1984c5c85 (diff)
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rbd: hook up cache options
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 <josh.durgin@inktank.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block')
-rw-r--r--block/rbd.c19
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);