When a read bio is attached to the stripe and the corresponding block is
marked as R5_UPTODATE, then a biofill operation is scheduled to copy
the data from the stripe cache to the bio buffer.

 Signed-off-by: Yuri Tikhonov <[EMAIL PROTECTED]>
 Signed-off-by: Mikhail Cherkashin <[EMAIL PROTECTED]>
--
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 9856a91..88f7e06 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3854,6 +3854,14 @@ static void handle_stripe6(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);
+
+       /* 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();
@@ -3866,33 +3874,16 @@ static void handle_stripe6(struct stripe_head *sh)
                if (test_and_clear_bit(i, sq->overwrite))
                        set_bit(R5_OVERWRITE, &dev->flags);
 
-               pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
-                       i, dev->flags, dev_q->toread, dev_q->towrite,
-                       dev_q->written);
-               /* maybe we can reply to a read */
-               if (test_bit(R5_UPTODATE, &dev->flags) && dev_q->toread) {
-                       struct bio *rbi, *rbi2;
-                       pr_debug("Return read for disc %d\n", i);
-                       spin_lock_irq(&conf->device_lock);
-                       rbi = dev_q->toread;
-                       dev_q->toread = NULL;
-                       clear_bit(i, sq->to_read);
-                       if (test_and_clear_bit(i, sq->overlap))
-                               wake_up(&conf->wait_for_overlap);
-                       spin_unlock_irq(&conf->device_lock);
-                       while (rbi && rbi->bi_sector <
-                              dev_q->sector + STRIPE_SECTORS) {
-                               copy_data(0, rbi, dev->page, dev_q->sector);
-                               rbi2 = r5_next_bio(rbi, dev_q->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 write %p "
+                       "written %p\n", i, dev->flags, dev_q->toread,
+                       dev_q->towrite, dev_q->written);
+               /* maybe we can reply to a read
+                * new wantfill requests are only permitted while
+                * STRIPE_OP_BIOFILL is clear
+                */
+               if (test_bit(R5_UPTODATE, &dev->flags) && dev_q->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++;
@@ -3925,6 +3916,10 @@ static void handle_stripe6(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,%d\n",
               s.locked, s.uptodate, s.to_read, s.to_write, s.failed,

-- 
Yuri Tikhonov, Senior Software Engineer
Emcraft Systems, www.emcraft.com
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