Commit 976ea8d4 authored by Dan Williams's avatar Dan Williams Committed by Neil Brown
Browse files

md: replace STRIPE_OP_COMPUTE_BLK with STRIPE_COMPUTE_RUN 



From: Dan Williams <dan.j.williams@intel.com>

Track the state of compute operations (recalculating a block from all the other
blocks in a stripe) with a state flag.  Reduces the scope of the
STRIPE_OP_COMPUTE_BLK flag to only tracking whether a compute operation has
been requested via the ops_request field of struct stripe_head_state.

Note, the compute operation that is performed in the course of doing a 'repair'
operation (check the parity block, recalculate it and write it back if the
check result is not zero) is tracked separately with the 'check_state'
variable.  Compute operations are held off while a 'check' is in progress, and
moving this check out to handle_issuing_new_read_requests5 the helper routine
__handle_issuing_new_read_requests5 can be simplified.

This is another step towards the removal of ops.{pending,ack,complete,count},
i.e. STRIPE_OP_COMPUTE_BLK only requests an operation and does not track the
state of the operation.

Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarNeil Brown <neilb@suse.de>
parent 83de75cc

drivers/md/raid5.c

+18 −47
Original line number Diff line number Diff line
@@ -604,8 +604,6 @@ static void ops_complete_compute5(void *stripe_head_ref) 
	clear_bit(STRIPE_COMPUTE_RUN, &sh->state);

	if (sh->check_state == check_state_compute_run)

		sh->check_state = check_state_compute_result;

	else

		set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);

	set_bit(STRIPE_HANDLE, &sh->state);

	release_stripe(sh);

}
@@ -881,8 +879,7 @@ static void raid5_run_ops(struct stripe_head *sh, unsigned long pending, 
		overlap_clear++;

	}



	if (test_bit(STRIPE_OP_COMPUTE_BLK, &pending) ||

	    test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request))

	if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request))

		tx = ops_run_compute5(sh, pending);



	if (test_bit(STRIPE_OP_PREXOR, &pending))
@@ -1960,12 +1957,6 @@ static int __handle_issuing_new_read_requests5(struct stripe_head *sh, 
	struct r5dev *dev = &sh->dev[disk_idx];

	struct r5dev *failed_dev = &sh->dev[s->failed_num];



	/* don't schedule compute operations or reads on the parity block while

	 * a check is in flight

	 */

	if (disk_idx == sh->pd_idx && sh->check_state)

		return ~0;



	/* is the data in this block needed, and can we get it? */

	if (!test_bit(R5_LOCKED, &dev->flags) &&

	    !test_bit(R5_UPTODATE, &dev->flags) && (dev->toread ||
@@ -1974,23 +1965,16 @@ static int __handle_issuing_new_read_requests5(struct stripe_head *sh, 
	     (failed_dev->toread || (failed_dev->towrite &&

	     !test_bit(R5_OVERWRITE, &failed_dev->flags)

	     ))))) {

		/* 1/ We would like to get this block, possibly by computing it,

		 * but we might not be able to.

		 *

		 * 2/ Since parity check operations potentially make the parity

		 * block !uptodate it will need to be refreshed before any

		 * compute operations on data disks are scheduled.

		 *

		 * 3/ We hold off parity block re-reads until check operations

		 * have quiesced.

		/* We would like to get this block, possibly by computing it,

		 * otherwise read it if the backing disk is insync

		 */

		if ((s->uptodate == disks - 1) && !sh->check_state &&

		if ((s->uptodate == disks - 1) &&

		    (s->failed && disk_idx == s->failed_num)) {

			set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);

			set_bit(STRIPE_COMPUTE_RUN, &sh->state);

			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);

			set_bit(R5_Wantcompute, &dev->flags);

			sh->ops.target = disk_idx;

			s->req_compute = 1;

			sh->ops.count++;

			/* Careful: from this point on 'uptodate' is in the eye

			 * of raid5_run_ops which services 'compute' operations

			 * before writes. R5_Wantcompute flags a block that will
@@ -1999,12 +1983,7 @@ static int __handle_issuing_new_read_requests5(struct stripe_head *sh, 
			 */

			s->uptodate++;

			return 0; /* uptodate + compute == disks */

		} else if ((s->uptodate < disks - 1) &&

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

			/* Note: we hold off compute operations while checks are

			 * in flight, but we still prefer 'compute' over 'read'

			 * hence we only read if (uptodate < * disks-1)

			 */

		} else if (test_bit(R5_Insync, &dev->flags)) {

			set_bit(R5_LOCKED, &dev->flags);

			set_bit(R5_Wantread, &dev->flags);

			s->locked++;
@@ -2021,18 +2000,11 @@ static void handle_issuing_new_read_requests5(struct stripe_head *sh, 
{

	int i;



	/* Clear completed compute operations */

	if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete)) {

		clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);

		clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack);

		clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);

	}



	/* look for blocks to read/compute, skip this if a compute

	 * is already in flight, or if the stripe contents are in the

	 * midst of changing due to a write

	 */

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

	if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&

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

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

		for (i = disks; i--; )
@@ -2236,8 +2208,7 @@ static void handle_issuing_new_write_requests5(raid5_conf_t *conf, 
	 * simultaneously.  If this is not the case then new writes need to be

	 * held off until the compute completes.

	 */

	if ((s->req_compute ||

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

	if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&

	    (s->locked == 0 && (rcw == 0 || rmw == 0) &&

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

		s->locked += handle_write_operations5(sh, rcw == 0, 0);
@@ -2410,6 +2381,7 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh, 
				set_bit(STRIPE_INSYNC, &sh->state);

			else {

				sh->check_state = check_state_compute_run;

				set_bit(STRIPE_COMPUTE_RUN, &sh->state);

				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);

				set_bit(R5_Wantcompute,

					&sh->dev[sh->pd_idx].flags);
@@ -2725,8 +2697,7 @@ static void handle_stripe5(struct stripe_head *sh) 
	 * or to load a block that is being partially written.

	 */

	if (s.to_read || s.non_overwrite ||

	    (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding ||

	    test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending))

	    (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding)

		handle_issuing_new_read_requests5(sh, &s, disks);



	/* Now we check to see if any write operations have recently
@@ -2803,7 +2774,7 @@ static void handle_stripe5(struct stripe_head *sh) 
	 */

	if (sh->check_state ||

	    (s.syncing && s.locked == 0 &&

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

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

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

		handle_parity_checks5(conf, sh, &s, disks);
@@ -2869,7 +2840,7 @@ static void handle_stripe5(struct stripe_head *sh) 
	}



	if (s.expanding && s.locked == 0 &&

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

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

		handle_stripe_expansion(conf, sh, NULL);



	if (sh->ops.count)
@@ -3089,7 +3060,7 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page) 
	}



	if (s.expanding && s.locked == 0 &&

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

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

		handle_stripe_expansion(conf, sh, &r6s);



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