md/raid10: unify handling of write completion.
NeilBrown [Sat, 10 Sep 2011 07:21:17 +0000 (17:21 +1000)]
A write can complete at two different places:
1/ when the last member-device write completes, through
   raid10_end_write_request
2/ in make_request() when we remove the initial bias from ->remaining.

These two should do exactly the same thing and the comment says they
do, but they don't.

So factor the correct code out into a function and call it in both
places.  This makes the code much more similar to RAID1.

The difference is only significant if there is an error, and they
usually take a while, so it is unlikely that there will be an error
already when make_request is completing, so this is unlikely to cause
real problems.

Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/raid10.c

index 8b29cd4..f6873fc 100644 (file)
@@ -337,6 +337,21 @@ static void close_write(r10bio_t *r10_bio)
        md_write_end(r10_bio->mddev);
 }
 
+static void one_write_done(r10bio_t *r10_bio)
+{
+       if (atomic_dec_and_test(&r10_bio->remaining)) {
+               if (test_bit(R10BIO_WriteError, &r10_bio->state))
+                       reschedule_retry(r10_bio);
+               else {
+                       close_write(r10_bio);
+                       if (test_bit(R10BIO_MadeGood, &r10_bio->state))
+                               reschedule_retry(r10_bio);
+                       else
+                               raid_end_bio_io(r10_bio);
+               }
+       }
+}
+
 static void raid10_end_write_request(struct bio *bio, int error)
 {
        int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
@@ -387,17 +402,7 @@ static void raid10_end_write_request(struct bio *bio, int error)
         * Let's see if all mirrored write operations have finished
         * already.
         */
-       if (atomic_dec_and_test(&r10_bio->remaining)) {
-               if (test_bit(R10BIO_WriteError, &r10_bio->state))
-                       reschedule_retry(r10_bio);
-               else {
-                       close_write(r10_bio);
-                       if (test_bit(R10BIO_MadeGood, &r10_bio->state))
-                               reschedule_retry(r10_bio);
-                       else
-                               raid_end_bio_io(r10_bio);
-               }
-       }
+       one_write_done(r10_bio);
        if (dec_rdev)
                rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
 }
@@ -1127,15 +1132,8 @@ retry_write:
                spin_unlock_irqrestore(&conf->device_lock, flags);
        }
 
-       if (atomic_dec_and_test(&r10_bio->remaining)) {
-               /* This matches the end of raid10_end_write_request() */
-               bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
-                               r10_bio->sectors,
-                               !test_bit(R10BIO_Degraded, &r10_bio->state),
-                               0);
-               md_write_end(mddev);
-               raid_end_bio_io(r10_bio);
-       }
+       /* Remove the bias on 'remaining' */
+       one_write_done(r10_bio);
 
        /* In case raid10d snuck in to freeze_array */
        wake_up(&conf->wait_barrier);