By opening a RBD volume in Read-Only we do not register a
watcher on the header object inside the Ceph cluster.
Refreshing a volume only calls rbd_stat() which is a operation
which does not write to a RBD image.
This allows us to use a cephx user which has no write
permissions if we would want to use the libvirt storage pool
for informational purposes only.
It also saves us a write into the Ceph cluster which should
speed up refreshing a RBD pool.
rbd_open_read_only() is available in all librbd versions which
also support rbd_open().
Signed-off-by: Wido den Hollander <w...@widodh.nl>
---
src/storage/storage_backend_rbd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/storage/storage_backend_rbd.c
b/src/storage/storage_backend_rbd.c
index 8c7a80d..3ab7912 100644
--- a/src/storage/storage_backend_rbd.c
+++ b/src/storage/storage_backend_rbd.c
@@ -283,7 +283,7 @@ static int
volStorageBackendRBDRefreshVolInfo(virStorageVolDefPtr vol,
int r = 0;
rbd_image_t image = NULL;
- r = rbd_open(ptr->ioctx, vol->name, &image, NULL);
+ r = rbd_open_read_only(ptr->ioctx, vol->name, &image, NULL);
if (r < 0) {
ret = -r;
virReportSystemError(-r, _("failed to open the RBD image '%s'"),
--
1.9.1
--
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