Re: [PATCH 4/4] md/raid5-cache: adjust the write position of the empty block and mark it as a checkpoint

[JackieLiu <liuyun01@xxxxxxxxxx>]

> 在 2016年12月3日，04:10，Shaohua Li <shli@xxxxxxxxxx> 写道：
> 
> confusing reading the code. Don't think a 'if () write_empty_block' makes the

Hi ShaoHua. 

I rewrote this part of the code, now without data_only_stripes, we write an empty block here,
with data_only_stripes, mark the first cache block as last_checkpoint.

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 9e72180..5697724 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -2072,7 +2072,6 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,
                return -ENOMEM;
        }

-       ctx->seq += 10;
        list_for_each_entry_safe(sh, next, &ctx->cached_list, lru) {
                struct r5l_meta_block *mb;
                int i;
@@ -2132,6 +2131,8 @@ 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;
+       struct stripe_head *sh;

        ctx.pos = log->last_checkpoint;
        ctx.seq = log->last_cp_seq;
@@ -2149,6 +2150,18 @@ static int r5l_recovery_log(struct r5l_log *log)
        if (ret)
                return ret;

+       pos = ctx.pos;
+       ctx.seq += 10;
+
+       if (ctx.data_only_stripes == 0) {
+               log->next_checkpoint = ctx.pos;
+               r5l_log_write_empty_meta_block(log, ctx.pos, ctx.seq++);
+               ctx.pos = r5l_ring_add(log, ctx.pos, BLOCK_SECTORS);
+       } else {
+               sh = list_last_entry(&ctx.cached_list, struct stripe_head, lru);
+               log->next_checkpoint = sh->log_start;
+       }
+
        if ((ctx.data_only_stripes == 0) && (ctx.data_parity_stripes == 0))
                pr_debug("md/raid:%s: starting from clean shutdown\n",
                         mdname(mddev));
@@ -2166,10 +2179,9 @@ static int r5l_recovery_log(struct r5l_log *log)
        }

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

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