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Commit 106f2e59 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'md/4.8-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md 

Pull MD fixes from Shaohua Li:
 "A few bug fixes for MD:

   - Guoqing fixed a bug compiling md-cluster in kernel

   - I fixed a potential deadlock in raid5-cache superblock write, a
     hang in raid5 reshape resume and a race condition introduced in
     rc4"

* tag 'md/4.8-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md:
  raid5: fix a small race condition
  md-cluster: make md-cluster also can work when compiled into kernel
  raid5: guarantee enough stripes to avoid reshape hang
  raid5-cache: fix a deadlock in superblock write
parents 309a18ae c9445555

drivers/md/md.c

+4 −8
Original line number Diff line number Diff line
@@ -7610,16 +7610,12 @@ EXPORT_SYMBOL(unregister_md_cluster_operations); 


int md_setup_cluster(struct mddev *mddev, int nodes)

{

	int err;



	err = request_module("md-cluster");

	if (err) {

		pr_err("md-cluster module not found.\n");

		return -ENOENT;

	}



	if (!md_cluster_ops)

		request_module("md-cluster");

	spin_lock(&pers_lock);

	/* ensure module won't be unloaded */

	if (!md_cluster_ops || !try_module_get(md_cluster_mod)) {

		pr_err("can't find md-cluster module or get it's reference.\n");

		spin_unlock(&pers_lock);

		return -ENOENT;

	}

drivers/md/raid5-cache.c

+15 −31
Original line number Diff line number Diff line
@@ -96,7 +96,6 @@ struct r5l_log { 
	spinlock_t no_space_stripes_lock;



	bool need_cache_flush;

	bool in_teardown;

};



/*
@@ -704,31 +703,22 @@ static void r5l_write_super_and_discard_space(struct r5l_log *log, 


	mddev = log->rdev->mddev;

	/*

	 * This is to avoid a deadlock. r5l_quiesce holds reconfig_mutex and

	 * wait for this thread to finish. This thread waits for

	 * MD_CHANGE_PENDING clear, which is supposed to be done in

	 * md_check_recovery(). md_check_recovery() tries to get

	 * reconfig_mutex. Since r5l_quiesce already holds the mutex,

	 * md_check_recovery() fails, so the PENDING never get cleared. The

	 * in_teardown check workaround this issue.

	 * Discard could zero data, so before discard we must make sure

	 * superblock is updated to new log tail. Updating superblock (either

	 * directly call md_update_sb() or depend on md thread) must hold

	 * reconfig mutex. On the other hand, raid5_quiesce is called with

	 * reconfig_mutex hold. The first step of raid5_quiesce() is waitting

	 * for all IO finish, hence waitting for reclaim thread, while reclaim

	 * thread is calling this function and waitting for reconfig mutex. So

	 * there is a deadlock. We workaround this issue with a trylock.

	 * FIXME: we could miss discard if we can't take reconfig mutex

	 */

	if (!log->in_teardown) {

	set_mask_bits(&mddev->flags, 0,

		BIT(MD_CHANGE_DEVS) | BIT(MD_CHANGE_PENDING));

		md_wakeup_thread(mddev->thread);

		wait_event(mddev->sb_wait,

			!test_bit(MD_CHANGE_PENDING, &mddev->flags) ||

			log->in_teardown);

		/*

		 * r5l_quiesce could run after in_teardown check and hold

		 * mutex first. Superblock might get updated twice.

		 */

		if (log->in_teardown)

			md_update_sb(mddev, 1);

	} else {

		WARN_ON(!mddev_is_locked(mddev));

	if (!mddev_trylock(mddev))

		return;

	md_update_sb(mddev, 1);

	}

	mddev_unlock(mddev);



	/* discard IO error really doesn't matter, ignore it */

	if (log->last_checkpoint < end) {
@@ -827,7 +817,6 @@ void r5l_quiesce(struct r5l_log *log, int state) 
	if (!log || state == 2)

		return;

	if (state == 0) {

		log->in_teardown = 0;

		/*

		 * This is a special case for hotadd. In suspend, the array has

		 * no journal. In resume, journal is initialized as well as the
@@ -838,11 +827,6 @@ void r5l_quiesce(struct r5l_log *log, int state) 
		log->reclaim_thread = md_register_thread(r5l_reclaim_thread,

					log->rdev->mddev, "reclaim");

	} else if (state == 1) {

		/*

		 * at this point all stripes are finished, so io_unit is at

		 * least in STRIPE_END state

		 */

		log->in_teardown = 1;

		/* make sure r5l_write_super_and_discard_space exits */

		mddev = log->rdev->mddev;

		wake_up(&mddev->sb_wait);

drivers/md/raid5.c

+12 −2
Original line number Diff line number Diff line
@@ -2423,10 +2423,10 @@ static void raid5_end_read_request(struct bio * bi) 
		}

	}

	rdev_dec_pending(rdev, conf->mddev);

	bio_reset(bi);

	clear_bit(R5_LOCKED, &sh->dev[i].flags);

	set_bit(STRIPE_HANDLE, &sh->state);

	raid5_release_stripe(sh);

	bio_reset(bi);

}



static void raid5_end_write_request(struct bio *bi)
@@ -2498,6 +2498,7 @@ static void raid5_end_write_request(struct bio *bi) 
	if (sh->batch_head && bi->bi_error && !replacement)

		set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);



	bio_reset(bi);

	if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))

		clear_bit(R5_LOCKED, &sh->dev[i].flags);

	set_bit(STRIPE_HANDLE, &sh->state);
@@ -2505,7 +2506,6 @@ static void raid5_end_write_request(struct bio *bi) 


	if (sh->batch_head && sh != sh->batch_head)

		raid5_release_stripe(sh->batch_head);

	bio_reset(bi);

}



static void raid5_build_block(struct stripe_head *sh, int i, int previous)
@@ -6639,6 +6639,16 @@ static struct r5conf *setup_conf(struct mddev *mddev) 
	}



	conf->min_nr_stripes = NR_STRIPES;

	if (mddev->reshape_position != MaxSector) {

		int stripes = max_t(int,

			((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4,

			((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4);

		conf->min_nr_stripes = max(NR_STRIPES, stripes);

		if (conf->min_nr_stripes != NR_STRIPES)

			printk(KERN_INFO

				"md/raid:%s: force stripe size %d for reshape\n",

				mdname(mddev), conf->min_nr_stripes);

	}

	memory = conf->min_nr_stripes * (sizeof(struct stripe_head) +

		 max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;

	atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);