[md PATCH 08/15] md/raid1, raid10: move rXbio accounting closer to allocation.

NeilBrown
2017-03-15T03:05:13Z

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>
---
drivers/md/raid1.c | 24 +++++++++++-------------
drivers/md/raid10.c | 22 +++++++++-------------
2 files changed, 20 insertions(+), 26 deletions(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index d3da6b36e670..7e509a894f15 100644
--- 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 b1b1f982a722..20029345f8b6 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1383,18 +1383,8 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
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;

@@ -1504,10 +1494,16 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
*/

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;