[libvirt] [PATCH 4/5] rbd: Add support for wiping RBD volumes using TRIM.
Using VIR_STORAGE_VOL_WIPE_ALG_TRIM a RBD volume can be trimmed down
to 0 bytes using rbd_dicard()
Effectively all the data on the volume will be lost/gone, but the volume
remains available for use afterwards.
Starting at offset 0 the storage pool will call rbd_discard() in stripe
size * count increments which is usually 4MB. Stripe size being 4MB and
count 1.
rbd_discard() is available since Ceph version Dumpling (0.67) which dates
back to August 2013.
Signed-off-by: Wido den Hollander <wido(a)widodh.nl>
---
src/storage/storage_backend_rbd.c | 42 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 41 insertions(+), 1 deletion(-)
diff --git a/src/storage/storage_backend_rbd.c b/src/storage/storage_backend_rbd.c
index 7e669ff..8a95388 100644
--- a/src/storage/storage_backend_rbd.c
+++ b/src/storage/storage_backend_rbd.c
@@ -772,6 +772,41 @@ virStorageBackendRBDVolWipeZero(rbd_image_t image,
}
static int
+virStorageBackendRBDVolWipeDiscard(rbd_image_t image,
+ char *imgname,
+ rbd_image_info_t info,
+ uint64_t stripe_count)
+{
+ int r = -1;
+ int ret = -1;
+ uint64_t offset = 0;
+ uint64_t length;
+
+ VIR_DEBUG("Wiping RBD %s volume using discard)", imgname);
+
+ while (offset < info.size) {
+ length = MIN((info.size - offset), (info.obj_size * stripe_count));
+
+ if ((r = rbd_discard(image, offset, length)) < 0) {
+ virReportSystemError(-r, _("discarding %zu bytes failed on "
+ "RBD image %s at offset %zu"),
+ length, imgname, offset);
+ goto cleanup;
+ }
+
+ VIR_DEBUG("Discarded %zu bytes of RBD image %s at offset %zu",
+ length, imgname, offset);
+
+ offset += length;
+ }
+
+ ret = 0;
+
+ cleanup:
+ return ret;
+}
+
+static int
virStorageBackendRBDVolWipe(virConnectPtr conn,
virStoragePoolObjPtr pool,
virStorageVolDefPtr vol,
@@ -787,7 +822,8 @@ virStorageBackendRBDVolWipe(virConnectPtr conn,
int r = -1;
int ret = -1;
- virCheckFlags(VIR_STORAGE_VOL_WIPE_ALG_ZERO, -1);
+ virCheckFlags(VIR_STORAGE_VOL_WIPE_ALG_ZERO |
+ VIR_STORAGE_VOL_WIPE_ALG_TRIM, -1);
VIR_DEBUG("Wiping RBD image %s/%s", pool->def->source.name,
vol->name);
@@ -823,6 +859,10 @@ virStorageBackendRBDVolWipe(virConnectPtr conn,
r = virStorageBackendRBDVolWipeZero(image, vol->name,
info, stripe_count);
break;
+ case VIR_STORAGE_VOL_WIPE_ALG_TRIM:
+ r = virStorageBackendRBDVolWipeDiscard(image, vol->name,
+ info, stripe_count);
+ break;
default:
virReportError(VIR_ERR_INVALID_ARG, _("unsupported algorithm %d"),
algorithm);
--
1.9.1