Commit 4b482044 authored by Shaohua Li's avatar Shaohua Li Committed by NeilBrown
Browse files

raid5-cache: add trim support for log 



Since superblock is updated infrequently, we do a simple trim of log
disk (a synchronous trim)

Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarNeilBrown <neilb@suse.com>
parent 9efdca16

drivers/md/raid5-cache.c

+62 −1
Original line number Diff line number Diff line
@@ -85,6 +85,7 @@ struct r5l_log { 
	spinlock_t no_space_stripes_lock;



	bool need_cache_flush;

	bool in_teardown;

};



/*
@@ -644,6 +645,60 @@ void r5l_flush_stripe_to_raid(struct r5l_log *log) 
}



static void r5l_write_super(struct r5l_log *log, sector_t cp);

static void r5l_write_super_and_discard_space(struct r5l_log *log,

	sector_t end)

{

	struct block_device *bdev = log->rdev->bdev;

	struct mddev *mddev;



	r5l_write_super(log, end);



	if (!blk_queue_discard(bdev_get_queue(bdev)))

		return;



	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.

	 */

	if (!log->in_teardown) {

		set_bit(MD_CHANGE_DEVS, &mddev->flags);

		set_bit(MD_CHANGE_PENDING, &mddev->flags);

		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));

		md_update_sb(mddev, 1);

	}



	if (log->last_checkpoint < end) {

		blkdev_issue_discard(bdev,

				log->last_checkpoint + log->rdev->data_offset,

				end - log->last_checkpoint, GFP_NOIO, 0);

	} else {

		blkdev_issue_discard(bdev,

				log->last_checkpoint + log->rdev->data_offset,

				log->device_size - log->last_checkpoint,

				GFP_NOIO, 0);

		blkdev_issue_discard(bdev, log->rdev->data_offset, end,

				GFP_NOIO, 0);

	}

}





static void r5l_do_reclaim(struct r5l_log *log)

{

	sector_t reclaim_target = xchg(&log->reclaim_target, 0);
@@ -685,7 +740,7 @@ static void r5l_do_reclaim(struct r5l_log *log) 
	 * here, because the log area might be reused soon and we don't want to

	 * confuse recovery

	 */

	r5l_write_super(log, next_checkpoint);

	r5l_write_super_and_discard_space(log, next_checkpoint);



	mutex_lock(&log->io_mutex);

	log->last_checkpoint = next_checkpoint;
@@ -721,9 +776,11 @@ static void r5l_wake_reclaim(struct r5l_log *log, sector_t space) 


void r5l_quiesce(struct r5l_log *log, int state)

{

	struct mddev *mddev;

	if (!log || state == 2)

		return;

	if (state == 0) {

		log->in_teardown = 0;

		log->reclaim_thread = md_register_thread(r5l_reclaim_thread,

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

	} else if (state == 1) {
@@ -731,6 +788,10 @@ void r5l_quiesce(struct r5l_log *log, int state) 
		 * 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);

		r5l_wake_reclaim(log, -1L);

		md_unregister_thread(&log->reclaim_thread);

		r5l_do_reclaim(log);