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rbd: hook up cache options

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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>
This commit is contained in:
Josh Durgin 2012-05-17 13:42:29 -07:00 committed by Kevin Wolf
parent 166acf546f
commit b11f38fcdf
1 changed files with 19 additions and 0 deletions
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19
block/rbd.c
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@ -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);