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md/raid5-cache: adjust the write position of the empty block if no data blocks 

When recovery is complete, we write an empty block and record his
position first, then make the data-only stripes rewritten done,
the location of the empty block as the last checkpoint position
to write into the super block. And we should update last_checkpoint
to this empty block position.

------------------------------------------------------------------
|  old log       | empty block | data only stripes | invalid log |
------------------------------------------------------------------
^                ^                                 ^
|                |- log->last_checkpoint           |- log->log_start
|                |- log->last_cp_seq               |- log->next_checkpoint
|- log->seq=n    |- log->seq=10+n

At the same time, if there is no data-only stripes, this scene may appear,
| meta1 | meta2 | meta3 |
meta 1 is valid, meta 2 is invalid. meta 3 could be valid. so we should
The solution is we create a new meta in meta2 with its seq == meta1's
seq + 10 and let superblock points to meta2.

Signed-off-by: JackieLiu <liuyun01@kylinos.cn>
Reviewed-by: Zhengyuan Liu <liuzhengyuan@kylinos.cn>
Reviewed-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
JackieLiu 2016-12-05 11:58:53 +08:00 committed by Shaohua Li
parent f687a33ef0
commit 43b9674832
1 changed files with 16 additions and 4 deletions
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20
drivers/md/raid5-cache.c
View File

@ -2077,7 +2077,6 @@ 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;
@ -2137,6 +2136,8 @@ 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;
@ -2154,6 +2155,18 @@ 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));
@ -2171,10 +2184,9 @@ 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;
}