Commit 393debc2 authored by Shaohua Li's avatar Shaohua Li
Browse files

md: separate request handling 



With commit cc27b0c7, pers->make_request could bail out without handling
the bio. If that happens, we should retry.  The commit fixes md_make_request
but not other call sites. Separate the request handling part, so other call
sites can use it.

Reported-by: default avatarNate Dailey <nate.dailey@stratus.com>
Fix: cc27b0c7(md: fix deadlock between mddev_suspend() and md_write_start())
Cc: stable@vger.kernel.org
Reviewed-by: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 4a704d6d

drivers/md/md.c

+33 −25
Original line number Diff line number Diff line
@@ -266,6 +266,37 @@ static DEFINE_SPINLOCK(all_mddevs_lock); 
 * call has finished, the bio has been linked into some internal structure

 * and so is visible to ->quiesce(), so we don't need the refcount any more.

 */

void md_handle_request(struct mddev *mddev, struct bio *bio)

{

check_suspended:

	rcu_read_lock();

	if (mddev->suspended) {

		DEFINE_WAIT(__wait);

		for (;;) {

			prepare_to_wait(&mddev->sb_wait, &__wait,

					TASK_UNINTERRUPTIBLE);

			if (!mddev->suspended)

				break;

			rcu_read_unlock();

			schedule();

			rcu_read_lock();

		}

		finish_wait(&mddev->sb_wait, &__wait);

	}

	atomic_inc(&mddev->active_io);

	rcu_read_unlock();



	if (!mddev->pers->make_request(mddev, bio)) {

		atomic_dec(&mddev->active_io);

		wake_up(&mddev->sb_wait);

		goto check_suspended;

	}



	if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)

		wake_up(&mddev->sb_wait);

}

EXPORT_SYMBOL(md_handle_request);



static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio)

{

	const int rw = bio_data_dir(bio);
@@ -285,23 +316,6 @@ static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio) 
		bio_endio(bio);

		return BLK_QC_T_NONE;

	}

check_suspended:

	rcu_read_lock();

	if (mddev->suspended) {

		DEFINE_WAIT(__wait);

		for (;;) {

			prepare_to_wait(&mddev->sb_wait, &__wait,

					TASK_UNINTERRUPTIBLE);

			if (!mddev->suspended)

				break;

			rcu_read_unlock();

			schedule();

			rcu_read_lock();

		}

		finish_wait(&mddev->sb_wait, &__wait);

	}

	atomic_inc(&mddev->active_io);

	rcu_read_unlock();



	/*

	 * save the sectors now since our bio can
@@ -310,20 +324,14 @@ check_suspended: 
	sectors = bio_sectors(bio);

	/* bio could be mergeable after passing to underlayer */

	bio->bi_opf &= ~REQ_NOMERGE;

	if (!mddev->pers->make_request(mddev, bio)) {

		atomic_dec(&mddev->active_io);

		wake_up(&mddev->sb_wait);

		goto check_suspended;

	}



	md_handle_request(mddev, bio);



	cpu = part_stat_lock();

	part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);

	part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], sectors);

	part_stat_unlock();



	if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)

		wake_up(&mddev->sb_wait);



	return BLK_QC_T_NONE;

}

drivers/md/md.h

+1 −0
Original line number Diff line number Diff line
@@ -692,6 +692,7 @@ extern void md_stop_writes(struct mddev *mddev); 
extern int md_rdev_init(struct md_rdev *rdev);

extern void md_rdev_clear(struct md_rdev *rdev);



extern void md_handle_request(struct mddev *mddev, struct bio *bio);

extern void mddev_suspend(struct mddev *mddev);

extern void mddev_resume(struct mddev *mddev);

extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,

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