dm vdo: remove internal ticket references

Signed-off-by: Susan LeGendre-McGhee <slegendr@redhat.com>
Signed-off-by: Matthew Sakai <msakai@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

1 files changed, 11 insertions, 5 deletions

diff --git a/drivers/md/dm-vdo/slab-depot.c b/drivers/md/dm-vdo/slab-depot.c
index 42126bd60242..5fa7e0838b32 100644
--- a/drivers/md/dm-vdo/slab-depot.c
+++ b/drivers/md/dm-vdo/slab-depot.c
@@ -334,7 +334,11 @@ static void launch_write(struct slab_summary_block *block)
 
 	/*
 	 * Flush before writing to ensure that the slab journal tail blocks and reference updates
-	 * covered by this summary update are stable (VDO-2332).
+	 * covered by this summary update are stable. Otherwise, a subsequent recovery could
+	 * encounter a slab summary update that refers to a slab journal tail block that has not
+	 * actually been written. In such cases, the slab journal referenced will be treated as
+	 * empty, causing any data within the slab which predates the existing recovery journal
+	 * entries to be lost.
 	 */
 	pbn = (depot->summary_origin +
 	       (VDO_SLAB_SUMMARY_BLOCKS_PER_ZONE * allocator->zone_number) +
@@ -499,7 +503,7 @@ static void reap_slab_journal(struct slab_journal *journal)
 	 * journal block writes can be issued while previous slab summary updates have not yet been
 	 * made. Even though those slab journal block writes will be ignored if the slab summary
 	 * update is not persisted, they may still overwrite the to-be-reaped slab journal block
-	 * resulting in a loss of reference count updates (VDO-2912).
+	 * resulting in a loss of reference count updates.
 	 */
 	journal->flush_waiter.callback = flush_for_reaping;
 	acquire_vio_from_pool(journal->slab->allocator->vio_pool,
@@ -770,7 +774,8 @@ static void write_slab_journal_block(struct vdo_waiter *waiter, void *context)
 
 	/*
 	 * This block won't be read in recovery until the slab summary is updated to refer to it.
-	 * The slab summary update does a flush which is sufficient to protect us from VDO-2331.
+	 * The slab summary update does a flush which is sufficient to protect us from corruption
+	 * due to out of order slab journal, reference block, or block map writes.
 	 */
 	vdo_submit_metadata_vio(uds_forget(vio), block_number, write_slab_journal_endio,
 				complete_write, REQ_OP_WRITE);
@@ -1201,7 +1206,8 @@ static void write_reference_block(struct vdo_waiter *waiter, void *context)
 
 	/*
 	 * Flush before writing to ensure that the recovery journal and slab journal entries which
-	 * cover this reference update are stable (VDO-2331).
+	 * cover this reference update are stable. This prevents data corruption that can be caused
+	 * by out of order writes.
 	 */
 	WRITE_ONCE(block->slab->allocator->ref_counts_statistics.blocks_written,
 		   block->slab->allocator->ref_counts_statistics.blocks_written + 1);
@@ -1775,7 +1781,7 @@ static void add_entries(struct slab_journal *journal)
 		    (journal->slab->status == VDO_SLAB_REBUILDING)) {
 			/*
 			 * Don't add entries while rebuilding or while a partial write is
-			 * outstanding (VDO-2399).
+			 * outstanding, as it could result in reference count corruption.
 			 */
 			break;
 		}