md/raid1, raid10: move rXbio accounting closer to allocation.

When raid1 or raid10 find they will need to allocate a new
r1bio/r10bio, in order to work around a known bad block, they
account for the allocation well before the allocation is
made.  This separation makes the correctness less obvious
and requires comments.

The accounting needs to be a little before: before the first
rXbio is submitted, but that is all.

So move the accounting down to where it makes more sense.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 730e57259af97b8d329c9c16a695f88ae7906f33..3afa60eb72c5165a435c6f1620358aa8f3e3a071 100644 (file)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1436,18 +1436,9 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio)
                goto retry_write;
        }
 
-       if (max_sectors < r1_bio->sectors) {
-               /* We are splitting this write into multiple parts, so
-                * we need to prepare for allocating another r1_bio.
-                */
+       if (max_sectors < r1_bio->sectors)
                r1_bio->sectors = max_sectors;
-               spin_lock_irq(&conf->device_lock);
-               if (bio->bi_phys_segments == 0)
-                       bio->bi_phys_segments = 2;
-               else
-                       bio->bi_phys_segments++;
-               spin_unlock_irq(&conf->device_lock);
-       }
+
        sectors_handled = r1_bio->sector + max_sectors - bio->bi_iter.bi_sector;
 
        atomic_set(&r1_bio->remaining, 1);
@@ -1553,10 +1544,17 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio)
         * as it could result in the bio being freed.
         */
        if (sectors_handled < bio_sectors(bio)) {
-               r1_bio_write_done(r1_bio);
-               /* We need another r1_bio.  It has already been counted
+               /* We need another r1_bio, which must be accounted
                 * in bio->bi_phys_segments
                 */
+               spin_lock_irq(&conf->device_lock);
+               if (bio->bi_phys_segments == 0)
+                       bio->bi_phys_segments = 2;
+               else
+                       bio->bi_phys_segments++;
+               spin_unlock_irq(&conf->device_lock);
+
+               r1_bio_write_done(r1_bio);
                r1_bio = alloc_r1bio(mddev, bio, sectors_handled);
                goto retry_write;
        }

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index e89a8d78a9ed537f417c414b2081ef5f9a97f291..c7c5b2693fc96ac2033524c067648c470bede1e9 100644 (file)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1384,18 +1384,8 @@ retry_write:
                goto retry_write;
        }
 
-       if (max_sectors < r10_bio->sectors) {
-               /* We are splitting this into multiple parts, so
-                * we need to prepare for allocating another r10_bio.
-                */
+       if (max_sectors < r10_bio->sectors)
                r10_bio->sectors = max_sectors;
-               spin_lock_irq(&conf->device_lock);
-               if (bio->bi_phys_segments == 0)
-                       bio->bi_phys_segments = 2;
-               else
-                       bio->bi_phys_segments++;
-               spin_unlock_irq(&conf->device_lock);
-       }
        sectors_handled = r10_bio->sector + max_sectors -
                bio->bi_iter.bi_sector;
 
@@ -1505,10 +1495,16 @@ retry_write:
         */
 
        if (sectors_handled < bio_sectors(bio)) {
-               one_write_done(r10_bio);
-               /* We need another r10_bio.  It has already been counted
+               /* We need another r10_bio and it needs to be counted
                 * in bio->bi_phys_segments.
                 */
+               spin_lock_irq(&conf->device_lock);
+               if (bio->bi_phys_segments == 0)
+                       bio->bi_phys_segments = 2;
+               else
+                       bio->bi_phys_segments++;
+               spin_unlock_irq(&conf->device_lock);
+               one_write_done(r10_bio);
                r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
 
                r10_bio->master_bio = bio;