add new system file

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2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/drivers/md/dm-cache-metadata.c
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@@ -551,11 +551,13 @@
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 	return r;
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 }
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-static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd)
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+static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd,
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+					      bool destroy_bm)
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 {
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 	dm_sm_destroy(cmd->metadata_sm);
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 	dm_tm_destroy(cmd->tm);
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-	dm_block_manager_destroy(cmd->bm);
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+	if (destroy_bm)
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+		dm_block_manager_destroy(cmd->bm);
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 }
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 typedef unsigned long (*flags_mutator)(unsigned long);
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@@ -826,7 +828,7 @@
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 		cmd2 = lookup(bdev);
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 		if (cmd2) {
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 			mutex_unlock(&table_lock);
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-			__destroy_persistent_data_objects(cmd);
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+			__destroy_persistent_data_objects(cmd, true);
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 			kfree(cmd);
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 			return cmd2;
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 		}
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@@ -874,7 +876,7 @@
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 		mutex_unlock(&table_lock);
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 		if (!cmd->fail_io)
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-			__destroy_persistent_data_objects(cmd);
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+			__destroy_persistent_data_objects(cmd, true);
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 		kfree(cmd);
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 	}
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 }
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@@ -1808,14 +1810,52 @@
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 int dm_cache_metadata_abort(struct dm_cache_metadata *cmd)
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 {
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-	int r;
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+	int r = -EINVAL;
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+	struct dm_block_manager *old_bm = NULL, *new_bm = NULL;
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+
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+	/* fail_io is double-checked with cmd->root_lock held below */
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+	if (unlikely(cmd->fail_io))
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+		return r;
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+
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+	/*
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+	 * Replacement block manager (new_bm) is created and old_bm destroyed outside of
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+	 * cmd root_lock to avoid ABBA deadlock that would result (due to life-cycle of
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+	 * shrinker associated with the block manager's bufio client vs cmd root_lock).
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+	 * - must take shrinker_rwsem without holding cmd->root_lock
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+	 */
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+	new_bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
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+					 CACHE_MAX_CONCURRENT_LOCKS);
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 	WRITE_LOCK(cmd);
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-	__destroy_persistent_data_objects(cmd);
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-	r = __create_persistent_data_objects(cmd, false);
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+	if (cmd->fail_io) {
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+		WRITE_UNLOCK(cmd);
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+		goto out;
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+	}
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+
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+	__destroy_persistent_data_objects(cmd, false);
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+	old_bm = cmd->bm;
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+	if (IS_ERR(new_bm)) {
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+		DMERR("could not create block manager during abort");
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+		cmd->bm = NULL;
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+		r = PTR_ERR(new_bm);
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+		goto out_unlock;
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+	}
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+
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+	cmd->bm = new_bm;
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+	r = __open_or_format_metadata(cmd, false);
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+	if (r) {
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+		cmd->bm = NULL;
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+		goto out_unlock;
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+	}
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+	new_bm = NULL;
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+out_unlock:
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 	if (r)
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 		cmd->fail_io = true;
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 	WRITE_UNLOCK(cmd);
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+	dm_block_manager_destroy(old_bm);
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+out:
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+	if (new_bm && !IS_ERR(new_bm))
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+		dm_block_manager_destroy(new_bm);
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 	return r;
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 }