[PATCH] raid5-cache: Fix the logic of raid5-cache recovery

["Jackie Liu" <liuyun01@kylinos.cn>]

Hi Song.

There is a doubt for r5l_recovery_log. I think we need write an empty block first,
then call r5c_recovery_rewrite_data_only_stripes functions. this empty 
block will be mark as the last_checkpoint. when the CACHING block is rewritten,
the superblock should be update this time. at the same time, we cann't be 
released the stripe_head at the front, it also be used in 
r5c_recovery_rewrite_data_only_stripes.

here is the patch

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 5f817bd..fad1808 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -67,7 +67,7 @@ static char *r5c_journal_mode_str[] = {"write-through",
 /*
  * raid5 cache state machine
  *
- * With rhe RAID cache, each stripe works in two phases:
+ * With the RAID cache, each stripe works in two phases:
  *	- caching phase
  *	- writing-out phase
  *
@@ -1674,7 +1674,6 @@ r5l_recovery_replay_one_stripe(struct r5conf *conf,

 static struct stripe_head *
 r5c_recovery_alloc_stripe(struct r5conf *conf,
-			  struct list_head *recovery_list,
 			  sector_t stripe_sect,
 			  sector_t log_start)
 {
@@ -1855,8 +1854,8 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log,
 						stripe_sect);

 		if (!sh) {
-			sh = r5c_recovery_alloc_stripe(conf, cached_stripe_list,
-						       stripe_sect, ctx->pos);
+			sh = r5c_recovery_alloc_stripe(conf, stripe_sect,
+							ctx->pos);
 			/*
 			 * cannot get stripe from raid5_get_active_stripe
 			 * try replay some stripes
@@ -1865,8 +1864,7 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log,
 				r5c_recovery_replay_stripes(
 					cached_stripe_list, ctx);
 				sh = r5c_recovery_alloc_stripe(
-					conf, cached_stripe_list,
-					stripe_sect, ctx->pos);
+					conf, stripe_sect, ctx->pos);
 			}
 			if (!sh) {
 				pr_debug("md/raid:%s: Increasing stripe cache size to %d to recovery data on journal.\n",
@@ -1875,8 +1873,7 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log,
 				raid5_set_cache_size(mddev,
 						     conf->min_nr_stripes * 2);
 				sh = r5c_recovery_alloc_stripe(
-					conf, cached_stripe_list, stripe_sect,
-					ctx->pos);
+					conf, stripe_sect, ctx->pos);
 			}
 			if (!sh) {
 				pr_err("md/raid:%s: Cannot get enough stripes due to memory pressure. Recovery failed.\n",
@@ -1986,8 +1983,6 @@ static int r5c_recovery_flush_log(struct r5l_log *log,
 	list_for_each_entry_safe(sh, next, &ctx->cached_list, lru) {
 		WARN_ON(!test_bit(STRIPE_R5C_CACHING, &sh->state));
 		r5c_recovery_load_one_stripe(log, sh);
-		list_del_init(&sh->lru);
-		raid5_release_stripe(sh);
 		ctx->data_only_stripes++;
 	}

@@ -2078,7 +2073,6 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,
 		return -ENOMEM;
 	}

-	ctx->seq += 10;
 	list_for_each_entry(sh, &ctx->cached_list, lru) {
 		struct r5l_meta_block *mb;
 		int i;
@@ -2090,7 +2084,7 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,
 						     ctx->pos, ctx->seq);
 		mb = page_address(page);
 		offset = le32_to_cpu(mb->meta_size);
-		write_pos = ctx->pos + BLOCK_SECTORS;
+		write_pos = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS);

 		for (i = sh->disks; i--; ) {
 			struct r5dev *dev = &sh->dev[i];
@@ -2125,6 +2119,9 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,
 		sh->log_start = ctx->pos;
 		ctx->pos = write_pos;
 		ctx->seq += 1;
+
+		list_del_init(&sh->lru);
+		raid5_release_stripe(sh);
 	}
 	__free_page(page);
 	return 0;
@@ -2135,6 +2132,7 @@ static int r5l_recovery_log(struct r5l_log *log)
 	struct mddev *mddev = log->rdev->mddev;
 	struct r5l_recovery_ctx ctx;
 	int ret;
+	sector_t pos;

 	ctx.pos = log->last_checkpoint;
 	ctx.seq = log->last_cp_seq;
@@ -2152,6 +2150,10 @@ static int r5l_recovery_log(struct r5l_log *log)
 	if (ret)
 		return ret;

+	pos = ctx.pos;
+	r5l_log_write_empty_meta_block(log, ctx.pos, (ctx.seq += 10));
+	ctx.pos = r5l_ring_add(log, ctx.pos, BLOCK_SECTORS);
+
 	if ((ctx.data_only_stripes == 0) && (ctx.data_parity_stripes == 0))
 		pr_debug("md/raid:%s: starting from clean shutdown\n",
 			 mdname(mddev));
@@ -2170,9 +2172,9 @@ static int r5l_recovery_log(struct r5l_log *log)

 	log->log_start = ctx.pos;
 	log->next_checkpoint = ctx.pos;
+	log->last_checkpoint = pos;
 	log->seq = ctx.seq;
-	r5l_log_write_empty_meta_block(log, ctx.pos, ctx.seq);
-	r5l_write_super(log, ctx.pos);
+	r5l_write_super(log, pos);
 	return 0;
 }

--
2.7.4

Thanks.
Jackie