md: replace STRIPE_OP_BIOFILL with STRIPE_BIOFILL_RUN

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

Track the state of read operations (copying data from the stripe cache to bio
buffers outside the lock) with a state flag.  Reduce the scope of the
STRIPE_OP_BIOFILL flag to only tracking whether a biofill operation has been
requested via the ops_request field of struct stripe_head_state.

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

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Neil Brown <neilb@suse.de>

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 544e160..b9c0a32 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -523,38 +523,34 @@ static void ops_complete_biofill(void *stripe_head_ref)
                (unsigned long long)sh->sector);
 
        /* clear completed biofills */
+       spin_lock_irq(&conf->device_lock);
        for (i = sh->disks; i--; ) {
                struct r5dev *dev = &sh->dev[i];
 
                /* acknowledge completion of a biofill operation */
                /* and check if we need to reply to a read request,
                 * new R5_Wantfill requests are held off until
-                * !test_bit(STRIPE_OP_BIOFILL, &sh->ops.pending)
+                * !STRIPE_BIOFILL_RUN
                 */
                if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
                        struct bio *rbi, *rbi2;
 
-                       /* The access to dev->read is outside of the
-                        * spin_lock_irq(&conf->device_lock), but is protected
-                        * by the STRIPE_OP_BIOFILL pending bit
-                        */
                        BUG_ON(!dev->read);
                        rbi = dev->read;
                        dev->read = NULL;
                        while (rbi && rbi->bi_sector <
                                dev->sector + STRIPE_SECTORS) {
                                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;
                        }
                }
        }
-       set_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
+       spin_unlock_irq(&conf->device_lock);
+       clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
 
        return_io(return_bi);
 
@@ -880,7 +876,7 @@ static void raid5_run_ops(struct stripe_head *sh, unsigned long pending,
        int overlap_clear = 0, i, disks = sh->disks;
        struct dma_async_tx_descriptor *tx = NULL;
 
-       if (test_bit(STRIPE_OP_BIOFILL, &pending)) {
+       if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
                ops_run_biofill(sh);
                overlap_clear++;
        }
@@ -2630,15 +2626,8 @@ static void handle_stripe5(struct stripe_head *sh)
        s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
        s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
        s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
-       /* Now to look around and see what can be done */
-
-       /* clean-up completed biofill operations */
-       if (test_bit(STRIPE_OP_BIOFILL, &sh->ops.complete)) {
-               clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
-               clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
-               clear_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
-       }
 
+       /* Now to look around and see what can be done */
        rcu_read_lock();
        for (i=disks; i--; ) {
                mdk_rdev_t *rdev;
@@ -2652,10 +2641,10 @@ static void handle_stripe5(struct stripe_head *sh)
                /* maybe we can request a biofill operation
                 *
                 * new wantfill requests are only permitted while
-                * STRIPE_OP_BIOFILL is clear
+                * ops_complete_biofill is guaranteed to be inactive
                 */
                if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
-                       !test_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))
+                   !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
                        set_bit(R5_Wantfill, &dev->flags);
 
                /* now count some things */
@@ -2699,8 +2688,10 @@ static void handle_stripe5(struct stripe_head *sh)
                goto unlock;
        }
 
-       if (s.to_fill && !test_and_set_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))
-               sh->ops.count++;
+       if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
+               set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
+               set_bit(STRIPE_BIOFILL_RUN, &sh->state);
+       }
 
        pr_debug("locked=%d uptodate=%d to_read=%d"
                " to_write=%d failed=%d failed_num=%d\n",