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Commit a9d56950 authored by NeilBrown's avatar NeilBrown
Browse files

md/raid5: need_this_block: start simplifying the last two conditions. 



Both the last two cases are only relevant if something has failed and
something needs to be written (but not over-written), and if it is OK
to pre-read blocks at this point.  So factor out those tests and
explain them.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent a79cfe12

drivers/md/raid5.c

+23 −5
Original line number Diff line number Diff line
@@ -2930,16 +2930,34 @@ static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s, 
		 */

		return 1;



	/* Sometimes neither read-modify-write nor reconstruct-write

	 * cycles can work.  In those cases we read every block we

	 * can.  Then the parity-update is certain to have enough to

	 * work with.

	 * This can only be a problem when we need to write something,

	 * and some device has failed.  If either of those tests

	 * fail we need look no further.

	 */

	if (!s->failed || !s->to_write)

		return 0;



	if (test_bit(R5_Insync, &dev->flags) &&

	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))

		/* Pre-reads at not permitted until after short delay

		 * to gather multiple requests.  However if this

		 * device is no Insync, the block could only be be computed

		 * and there is no need to delay that.

		 */

		return 0;

	if (

	     (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&

	      (!test_bit(R5_Insync, &dev->flags) || test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) &&

	     (sh->raid_conf->level <= 5 && fdev[0]->towrite &&

	      !test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||

	     ((sh->raid_conf->level == 6 ||

	       sh->sector >= sh->raid_conf->mddev->recovery_cp)

	      && s->failed && s->to_write &&

	      &&

	      (s->to_write - s->non_overwrite <

	       sh->raid_conf->raid_disks - sh->raid_conf->max_degraded) &&

	      (!test_bit(R5_Insync, &dev->flags) || test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))))

	       sh->raid_conf->raid_disks - sh->raid_conf->max_degraded)

	      ))

		return 1;

	return 0;

}