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lib/blob: extent_page shall never occupy md page 0

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Search for md_page to be used as extent page started
from 0, which is completely valid md_page.

This page can be free when for example blob with id 0
was deleted and some other requested a new page for extent.

There are already existing blobs that have extents
pointing to 0, which means unallocated.
Unfortunetly it means 0 can never mean md page 0.
If that already occured for someone, this extent page was already
lost during blob/bs reload and nothing can be done.

With this in mind following assumptions are made for extent pages:
- 0 means unallocated extent page
- UINT32_MAX means we ran out of md pages, and should not be persisted
- [NEW] extent page can never occupy md page 0

That last one is new addition in this patch.
bs_allocate_cluster will now always try to find md page from 1 or higher.

Signed-off-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Change-Id: Ia17ce5bbca2fab4fb4487e4e263f3a0aa120bf17
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/4314
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Mellanox Build Bot
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
This commit is contained in:
Tomasz Zawadzki 2020-09-17 12:58:45 -04:00
parent 63e257ed34
commit 7f139e549b
2 changed files with 9 additions and 1 deletions
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4
lib/blob/blobstore.c
View File

@ -165,6 +165,10 @@ bs_allocate_cluster(struct spdk_blob *blob, uint32_t cluster_num,
if (blob->use_extent_table) {
extent_page = bs_cluster_to_extent_page(blob, cluster_num);
if (*extent_page == 0) {
/* Extent page shall never occupy md_page so start the search from 1 */
if (*lowest_free_md_page == 0) {
*lowest_free_md_page = 1;
}
/* No extent_page is allocated for the cluster */
*lowest_free_md_page = spdk_bit_array_find_first_clear(blob->bs->used_md_pages,
*lowest_free_md_page);

6
test/unit/lib/blob/blob.c/blob_ut.c
View File

@ -3769,7 +3769,7 @@ blob_thin_prov_rw(void)
{
static const uint8_t zero[10 * 4096] = { 0 };
struct spdk_blob_store *bs = g_bs;
struct spdk_blob *blob;
struct spdk_blob *blob, *blob_id0;
struct spdk_io_channel *channel, *channel_thread1;
struct spdk_blob_opts opts;
uint64_t free_clusters;
@ -3788,7 +3788,11 @@ blob_thin_prov_rw(void)
ut_spdk_blob_opts_init(&opts);
opts.thin_provision = true;
/* Create and delete blob at md page 0, so that next md page allocation
* for extent will use that. */
blob_id0 = ut_blob_create_and_open(bs, &opts);
blob = ut_blob_create_and_open(bs, &opts);
ut_blob_close_and_delete(bs, blob_id0);
CU_ASSERT(free_clusters == spdk_bs_free_cluster_count(bs));
CU_ASSERT(blob->active.num_clusters == 0);