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Commit a85dd7b8 authored by Song Liu's avatar Song Liu Committed by Shaohua Li
Browse files

md/r5cache: flush data only stripes in r5l_recovery_log() 



For safer operation, all arrays start in write-through mode, which has been
better tested and is more mature. And actually the write-through/write-mode
isn't persistent after array restarted, so we always start array in
write-through mode. However, if recovery found data-only stripes before the
shutdown (from previous write-back mode), it is not safe to start the array in
write-through mode, as write-through mode can not handle stripes with data in
write-back cache. To solve this problem, we flush all data-only stripes in
r5l_recovery_log(). When r5l_recovery_log() returns, the array starts with
empty cache in write-through mode.

This logic is implemented in r5c_recovery_flush_data_only_stripes():

1. enable write back cache
2. flush all stripes
3. wake up conf->mddev->thread
4. wait for all stripes get flushed (reuse wait_for_quiescent)
5. disable write back cache

The wait in 4 will be waked up in release_inactive_stripe_list()
when conf->active_stripes reaches 0.

It is safe to wake up mddev->thread here because all the resource
required for the thread has been initialized.

Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent ba02684d

drivers/md/md.c

+5 −0
Original line number Diff line number Diff line
@@ -5291,6 +5291,11 @@ int md_run(struct mddev *mddev) 
	if (start_readonly && mddev->ro == 0)

		mddev->ro = 2; /* read-only, but switch on first write */



	/*

	 * NOTE: some pers->run(), for example r5l_recovery_log(), wakes

	 * up mddev->thread. It is important to initialize critical

	 * resources for mddev->thread BEFORE calling pers->run().

	 */

	err = pers->run(mddev);

	if (err)

		pr_warn("md: pers->run() failed ...\n");

drivers/md/raid5-cache.c

+40 −16
Original line number Diff line number Diff line
@@ -2060,7 +2060,7 @@ static int 
r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,

				       struct r5l_recovery_ctx *ctx)

{

	struct stripe_head *sh, *next;

	struct stripe_head *sh;

	struct mddev *mddev = log->rdev->mddev;

	struct page *page;

	sector_t next_checkpoint = MaxSector;
@@ -2074,7 +2074,7 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log, 


	WARN_ON(list_empty(&ctx->cached_list));



	list_for_each_entry_safe(sh, next, &ctx->cached_list, lru) {

	list_for_each_entry(sh, &ctx->cached_list, lru) {

		struct r5l_meta_block *mb;

		int i;

		int offset;
@@ -2124,14 +2124,39 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log, 
		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;

}



static void r5c_recovery_flush_data_only_stripes(struct r5l_log *log,

						 struct r5l_recovery_ctx *ctx)

{

	struct mddev *mddev = log->rdev->mddev;

	struct r5conf *conf = mddev->private;

	struct stripe_head *sh, *next;



	if (ctx->data_only_stripes == 0)

		return;



	log->r5c_journal_mode = R5C_JOURNAL_MODE_WRITE_BACK;



	list_for_each_entry_safe(sh, next, &ctx->cached_list, lru) {

		r5c_make_stripe_write_out(sh);

		set_bit(STRIPE_HANDLE, &sh->state);

		list_del_init(&sh->lru);

		raid5_release_stripe(sh);

	}



	md_wakeup_thread(conf->mddev->thread);

	/* reuse conf->wait_for_quiescent in recovery */

	wait_event(conf->wait_for_quiescent,

		   atomic_read(&conf->active_stripes) == 0);



	log->r5c_journal_mode = R5C_JOURNAL_MODE_WRITE_THROUGH;

}



static int r5l_recovery_log(struct r5l_log *log)

{

	struct mddev *mddev = log->rdev->mddev;
@@ -2158,32 +2183,31 @@ static int r5l_recovery_log(struct r5l_log *log) 
	pos = ctx.pos;

	ctx.seq += 10000;



	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);

	}



	if ((ctx.data_only_stripes == 0) && (ctx.data_parity_stripes == 0))

		pr_debug("md/raid:%s: starting from clean shutdown\n",

			 mdname(mddev));

	else {

	else

		pr_debug("md/raid:%s: recovering %d data-only stripes and %d data-parity stripes\n",

			 mdname(mddev), ctx.data_only_stripes,

			 ctx.data_parity_stripes);



		if (ctx.data_only_stripes > 0)

			if (r5c_recovery_rewrite_data_only_stripes(log, &ctx)) {

	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 if (r5c_recovery_rewrite_data_only_stripes(log, &ctx)) {

		pr_err("md/raid:%s: failed to rewrite stripes to journal\n",

		       mdname(mddev));

		return -EIO;

	}

	}



	log->log_start = ctx.pos;

	log->seq = ctx.seq;

	log->last_checkpoint = pos;

	r5l_write_super(log, pos);



	r5c_recovery_flush_data_only_stripes(log, &ctx);

	return 0;

}