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blob: allow bdev_lvol_set_parent when child has more clusters than parent #73

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Merged
derekbit merged 1 commit into from
Jun 12, 2026
Merged

blob: allow bdev_lvol_set_parent when child has more clusters than parent #73

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5 changes: 4 additions & 1 deletion include/spdk/blob.h
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Original file line number Diff line number Diff line change
Expand Up @@ -922,7 +922,10 @@ int spdk_bs_blob_deep_copy(struct spdk_blob_store *bs, struct spdk_io_channel *c
* This call set a snapshot as the parent of a blob, making the blob a clone of this snapshot.
* The previous parent of the blob, if any, can be another snapshot or an external snapshot; if
* the blob is not a clone, it must be thin-provisioned.
* Blob and parent snapshot must have the same size.
* The blob must have at least as many clusters as the parent snapshot
* (child cluster count >= parent cluster count). A child with more clusters
* than the parent is valid; reads beyond the parent range return zeros via
* thin provisioning.
Comment on lines +925 to +928
*
* \param bs blobstore.
* \param blob_id The id of the blob.
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5 changes: 3 additions & 2 deletions lib/blob/blobstore.c
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Expand Up @@ -8311,8 +8311,9 @@ bs_set_parent_snapshot_open_cpl(void *cb_arg, struct spdk_blob *snapshot, int bs
return;
}

if (blob->active.num_clusters != snapshot->active.num_clusters) {
SPDK_ERRLOG("parent blob has a number of clusters different from child's ones\n");
if (blob->active.num_clusters < snapshot->active.num_clusters) {
SPDK_ERRLOG("child blob has fewer clusters (%" PRIu64 ") than parent snapshot (%" PRIu64 ")\n",
blob->active.num_clusters, snapshot->active.num_clusters);
ctx->bserrno = -EINVAL;
spdk_blob_close(blob, bs_set_parent_close_snapshot, ctx);
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return;
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30 changes: 22 additions & 8 deletions test/unit/lib/blob/blob.c/blob_ut.c
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Expand Up @@ -10393,14 +10393,14 @@ blob_set_parent(void)
struct spdk_blob_store *bs = g_bs;
struct spdk_blob_opts opts;
struct ut_esnap_opts esnap_opts;
struct spdk_blob *blob1, *blob2, *blob3, *blob4, *blob5;
spdk_blob_id blobid1, blobid2, blobid3, blobid4, blobid5,
struct spdk_blob *blob1, *blob2, *blob3, *blob4, *blob5, *blob6;
spdk_blob_id blobid1, blobid2, blobid3, blobid4, blobid5, blobid6,
snapshotid1, snapshotid2, snapshotid3;
uint32_t cluster_sz, block_sz;
const uint32_t esnap_num_clusters = 4;
uint64_t esnap_num_blocks;
spdk_blob_id ids[2];
size_t clone_count = 2;
spdk_blob_id ids[3];
size_t clone_count = 3;

cluster_sz = spdk_bs_get_cluster_size(bs);
block_sz = spdk_bs_get_io_unit_size(bs);
Expand Down Expand Up @@ -10453,10 +10453,10 @@ blob_set_parent(void)
poll_threads();
CU_ASSERT(g_bserrno == -EINVAL);

/* Call set_parent with blob and snapshot of different size */
/* Call set_parent with blob that has more clusters than snapshot (child > parent, now succeeds) */
spdk_bs_blob_set_parent(bs, blobid2, snapshotid1, blob_op_complete, NULL);
poll_threads();
CU_ASSERT(g_bserrno == -EINVAL);
CU_ASSERT(g_bserrno == 0);
Comment on lines +10456 to +10459

/* Call set_parent correctly with a snapshot's clone blob */
spdk_bs_blob_set_parent(bs, blobid1, snapshotid1, blob_op_complete, NULL);
Expand All @@ -10467,8 +10467,8 @@ blob_set_parent(void)
CU_ASSERT(spdk_blob_is_clone(blob1));
CU_ASSERT(spdk_blob_get_parent_snapshot(bs, blobid1) == snapshotid1);
CU_ASSERT(spdk_blob_get_clones(bs, snapshotid1, ids, &clone_count) == 0);
CU_ASSERT(clone_count == 2);
CU_ASSERT(ids[1] == blobid1);
CU_ASSERT(clone_count == 3);
CU_ASSERT(ids[2] == blobid1);

/* Create another normal blob with size equal to esnap size and make a snapshot */
ut_spdk_blob_opts_init(&opts);
Expand All @@ -10483,6 +10483,19 @@ blob_set_parent(void)
SPDK_CU_ASSERT_FATAL(g_blobid != SPDK_BLOBID_INVALID);
snapshotid3 = g_blobid;

/* Create a thin-provisioned blob with fewer clusters than snapshotid3 to verify child < parent fails */
ut_spdk_blob_opts_init(&opts);
opts.num_clusters = esnap_num_clusters / 2;
opts.thin_provision = true;
blob6 = ut_blob_create_and_open(bs, &opts);
SPDK_CU_ASSERT_FATAL(blob6 != NULL);
blobid6 = spdk_blob_get_id(blob6);

/* Call set_parent with child having fewer clusters than parent snapshot (should fail) */
spdk_bs_blob_set_parent(bs, blobid6, snapshotid3, blob_op_complete, NULL);
poll_threads();
CU_ASSERT(g_bserrno == -EINVAL);

/* Call set_parent correctly with an esnap's clone blob */
spdk_bs_blob_set_parent(bs, blobid2, snapshotid3, blob_op_complete, NULL);
poll_threads();
Expand Down Expand Up @@ -10530,6 +10543,7 @@ blob_set_parent(void)
/* Clean up */
ut_blob_close_and_delete(bs, blob5);
ut_blob_close_and_delete(bs, blob4);
ut_blob_close_and_delete(bs, blob6);
ut_blob_close_and_delete(bs, blob3);
ut_blob_close_and_delete(bs, blob2);
ut_blob_close_and_delete(bs, blob1);
Expand Down
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