md/r5cache: simplify handling of sh->log_start in recovery

We only need to update sh->log_start at the end of recovery,
which is r5c_recovery_rewrite_data_only_stripes(), so it is not
necessary to set it before that. In this patch, log_start is
removed from r5c_recovery_alloc_stripe().

After updating all sh->log_start, rewrite_data_only_stripes()
also updates log->next_checkpoints to the last sh->log_start.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>

1 files changed, 12 insertions, 15 deletions

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 49aea4231084..b178a8fef266 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -1682,8 +1682,7 @@ out:
 
 static struct stripe_head *
 r5c_recovery_alloc_stripe(struct r5conf *conf,
-                          sector_t stripe_sect,
-                          sector_t log_start)
+                          sector_t stripe_sect)
 {
         struct stripe_head *sh;
 
@@ -1692,7 +1691,6 @@ r5c_recovery_alloc_stripe(struct r5conf *conf,
                 return NULL;  /* no more stripe available */
 
         r5l_recovery_reset_stripe(sh);
-        sh->log_start = log_start;
 
         return sh;
 }
@@ -1862,7 +1860,7 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log,
                                                 stripe_sect);
 
                 if (!sh) {
-                        sh = r5c_recovery_alloc_stripe(conf, stripe_sect, ctx->pos);
+                        sh = r5c_recovery_alloc_stripe(conf, stripe_sect);
                         /*
                          * cannot get stripe from raid5_get_active_stripe
                          * try replay some stripes
@@ -1871,7 +1869,7 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log,
                                 r5c_recovery_replay_stripes(
                                         cached_stripe_list, ctx);
                                 sh = r5c_recovery_alloc_stripe(
-                                        conf, stripe_sect, ctx->pos);
+                                        conf, stripe_sect);
                         }
                         if (!sh) {
                                 pr_debug("md/raid:%s: Increasing stripe cache size to %d to recovery data on journal.\n",
@@ -1879,8 +1877,8 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log,
                                         conf->min_nr_stripes * 2);
                                 raid5_set_cache_size(mddev,
                                                      conf->min_nr_stripes * 2);
-                                sh = r5c_recovery_alloc_stripe(
-                                        conf, stripe_sect, ctx->pos);
+                                sh = r5c_recovery_alloc_stripe(conf,
+                                                               stripe_sect);
                         }
                         if (!sh) {
                                 pr_err("md/raid:%s: Cannot get enough stripes due to memory pressure. Recovery failed.\n",
@@ -1894,7 +1892,6 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log,
                         if (!test_bit(STRIPE_R5C_CACHING, &sh->state) &&
                             test_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags)) {
                                 r5l_recovery_replay_one_stripe(conf, sh, ctx);
-                                sh->log_start = ctx->pos;
                                 list_move_tail(&sh->lru, cached_stripe_list);
                         }
                         r5l_recovery_load_data(log, sh, ctx, payload,
@@ -1933,8 +1930,6 @@ static void r5c_recovery_load_one_stripe(struct r5l_log *log,
                         set_bit(R5_UPTODATE, &dev->flags);
                 }
         }
-        list_add_tail(&sh->r5c, &log->stripe_in_journal_list);
-        atomic_inc(&log->stripe_in_journal_count);
 }
 
 /*
@@ -2070,6 +2065,7 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,
         struct stripe_head *sh, *next;
         struct mddev *mddev = log->rdev->mddev;
         struct page *page;
+        sector_t next_checkpoint = MaxSector;
 
         page = alloc_page(GFP_KERNEL);
         if (!page) {
@@ -2078,6 +2074,8 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,
                 return -ENOMEM;
         }
 
+        WARN_ON(list_empty(&ctx->cached_list));
+
         list_for_each_entry_safe(sh, next, &ctx->cached_list, lru) {
                 struct r5l_meta_block *mb;
                 int i;
@@ -2123,12 +2121,15 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,
                 sync_page_io(log->rdev, ctx->pos, PAGE_SIZE, page,
                              REQ_OP_WRITE, REQ_FUA, false);
                 sh->log_start = ctx->pos;
+                list_add_tail(&sh->r5c, &log->stripe_in_journal_list);
+                atomic_inc(&log->stripe_in_journal_count);
                 ctx->pos = write_pos;
                 ctx->seq += 1;
-
+                next_checkpoint = sh->log_start;
                 list_del_init(&sh->lru);
                 raid5_release_stripe(sh);
         }
+        log->next_checkpoint = next_checkpoint;
         __free_page(page);
         return 0;
 }
@@ -2139,7 +2140,6 @@ static int r5l_recovery_log(struct r5l_log *log)
         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;
@@ -2164,9 +2164,6 @@ static int r5l_recovery_log(struct r5l_log *log)
                 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))