Commit b5e98d65 authored by Dan Williams's avatar Dan Williams
Browse files

md: handle_stripe5 - add request/completion logic for async read ops 



When a read bio is attached to the stripe and the corresponding block is
marked R5_UPTODATE, then a read (biofill) operation is scheduled to copy
the data from the stripe cache to the bio buffer.  handle_stripe flags the
blocks to be operated on with the R5_Wantfill flag.  If new read requests
arrive while raid5_run_ops is running they will not be handled until
handle_stripe is scheduled to run again.

Changelog:
* cleanup to_read and to_fill accounting
* do not fail reads that have reached the cache

Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Acked-By: default avatarNeilBrown <neilb@suse.de>
parent e89f8962

drivers/md/raid5.c

+25 −28
Original line number Diff line number Diff line
@@ -2049,9 +2049,12 @@ handle_requests_to_failed_array(raid5_conf_t *conf, struct stripe_head *sh, 
			bi = bi2;

		}



		/* fail any reads if this device is non-operational */

		if (!test_bit(R5_Insync, &sh->dev[i].flags) ||

		    test_bit(R5_ReadError, &sh->dev[i].flags)) {

		/* fail any reads if this device is non-operational and

		 * the data has not reached the cache yet.

		 */

		if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&

		    (!test_bit(R5_Insync, &sh->dev[i].flags) ||

		      test_bit(R5_ReadError, &sh->dev[i].flags))) {

			bi = sh->dev[i].toread;

			sh->dev[i].toread = NULL;

			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
@@ -2740,37 +2743,27 @@ static void handle_stripe5(struct stripe_head *sh) 
		struct r5dev *dev = &sh->dev[i];

		clear_bit(R5_Insync, &dev->flags);



		pr_debug("check %d: state 0x%lx read %p write %p written %p\n",

			i, dev->flags, dev->toread, dev->towrite, dev->written);

		/* maybe we can reply to a read */

		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {

			struct bio *rbi, *rbi2;

			pr_debug("Return read for disc %d\n", i);

			spin_lock_irq(&conf->device_lock);

			rbi = dev->toread;

			dev->toread = NULL;

			if (test_and_clear_bit(R5_Overlap, &dev->flags))

				wake_up(&conf->wait_for_overlap);

			spin_unlock_irq(&conf->device_lock);

			while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {

				copy_data(0, rbi, dev->page, dev->sector);

				rbi2 = r5_next_bio(rbi, dev->sector);

				spin_lock_irq(&conf->device_lock);

				if (--rbi->bi_phys_segments == 0) {

					rbi->bi_next = return_bi;

					return_bi = rbi;

				}

				spin_unlock_irq(&conf->device_lock);

				rbi = rbi2;

			}

		}

		pr_debug("check %d: state 0x%lx toread %p read %p write %p "

			"written %p\n",	i, dev->flags, dev->toread, dev->read,

			dev->towrite, dev->written);



		/* maybe we can request a biofill operation

		 *

		 * new wantfill requests are only permitted while

		 * STRIPE_OP_BIOFILL is clear

		 */

		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&

			!test_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))

			set_bit(R5_Wantfill, &dev->flags);



		/* now count some things */

		if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;

		if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;

		if (test_bit(R5_Wantcompute, &dev->flags)) s.compute++;



		if (dev->toread)

		if (test_bit(R5_Wantfill, &dev->flags))

			s.to_fill++;

		else if (dev->toread)

			s.to_read++;

		if (dev->towrite) {

			s.to_write++;
@@ -2793,6 +2786,10 @@ static void handle_stripe5(struct stripe_head *sh) 
			set_bit(R5_Insync, &dev->flags);

	}

	rcu_read_unlock();



	if (s.to_fill && !test_and_set_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))

		sh->ops.count++;



	pr_debug("locked=%d uptodate=%d to_read=%d"

		" to_write=%d failed=%d failed_num=%d\n",

		s.locked, s.uptodate, s.to_read, s.to_write,

include/linux/raid/raid5.h

+1 −1
Original line number Diff line number Diff line
@@ -200,7 +200,7 @@ struct stripe_head { 
struct stripe_head_state {

	int syncing, expanding, expanded;

	int locked, uptodate, to_read, to_write, failed, written;

	int compute, req_compute, non_overwrite;

	int to_fill, compute, req_compute, non_overwrite;

	int failed_num;

};

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