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>

1 files changed, 12 insertions, 21 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 544e1600f208..b9c0a32a4f95 100644
--- 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",