Re: [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&gt; --- 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);