[PATCH] md: pass down BIO_RW_SYNC in raid{1,10}

md raidX make_request functions strip off the BIO_RW_SYNC flag, thus
introducing additional latency.

Fixing this in raid1 and raid10 seems to be straightforward enough.

For our particular usage case in DRBD, passing this flag improved some
initialization time from ~5 minutes to ~5 seconds.

Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Lars Ellenberg <lars@linbit.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index b30f74be3982ce8fbfad91a5204cc7e49799479d..164b25dca10157b9333ef40d5409890f4da7cabb 100644 (file)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -775,6 +775,7 @@ static int make_request(request_queue_t *q, struct bio * bio)
        struct bio_list bl;
        struct page **behind_pages = NULL;
        const int rw = bio_data_dir(bio);
+       const int do_sync = bio_sync(bio);
        int do_barriers;
 
        /*
@@ -835,7 +836,7 @@ static int make_request(request_queue_t *q, struct bio * bio)
                read_bio->bi_sector = r1_bio->sector + mirror->rdev->data_offset;
                read_bio->bi_bdev = mirror->rdev->bdev;
                read_bio->bi_end_io = raid1_end_read_request;
-               read_bio->bi_rw = READ;
+               read_bio->bi_rw = READ | do_sync;
                read_bio->bi_private = r1_bio;
 
                generic_make_request(read_bio);
@@ -906,7 +907,7 @@ static int make_request(request_queue_t *q, struct bio * bio)
                mbio->bi_sector = r1_bio->sector + conf->mirrors[i].rdev->data_offset;
                mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
                mbio->bi_end_io = raid1_end_write_request;
-               mbio->bi_rw = WRITE | do_barriers;
+               mbio->bi_rw = WRITE | do_barriers | do_sync;
                mbio->bi_private = r1_bio;
 
                if (behind_pages) {
@@ -941,6 +942,8 @@ static int make_request(request_queue_t *q, struct bio * bio)
        blk_plug_device(mddev->queue);
        spin_unlock_irqrestore(&conf->device_lock, flags);
 
+       if (do_sync)
+               md_wakeup_thread(mddev->thread);
 #if 0
        while ((bio = bio_list_pop(&bl)) != NULL)
                generic_make_request(bio);
@@ -1541,6 +1544,7 @@ static void raid1d(mddev_t *mddev)
                         * We already have a nr_pending reference on these rdevs.
                         */
                        int i;
+                       const int do_sync = bio_sync(r1_bio->master_bio);
                        clear_bit(R1BIO_BarrierRetry, &r1_bio->state);
                        clear_bit(R1BIO_Barrier, &r1_bio->state);
                        for (i=0; i < conf->raid_disks; i++)
@@ -1561,7 +1565,7 @@ static void raid1d(mddev_t *mddev)
                                                conf->mirrors[i].rdev->data_offset;
                                        bio->bi_bdev = conf->mirrors[i].rdev->bdev;
                                        bio->bi_end_io = raid1_end_write_request;
-                                       bio->bi_rw = WRITE;
+                                       bio->bi_rw = WRITE | do_sync;
                                        bio->bi_private = r1_bio;
                                        r1_bio->bios[i] = bio;
                                        generic_make_request(bio);
@@ -1593,6 +1597,7 @@ static void raid1d(mddev_t *mddev)
                                       (unsigned long long)r1_bio->sector);
                                raid_end_bio_io(r1_bio);
                        } else {
+                               const int do_sync = bio_sync(r1_bio->master_bio);
                                r1_bio->bios[r1_bio->read_disk] =
                                        mddev->ro ? IO_BLOCKED : NULL;
                                r1_bio->read_disk = disk;
@@ -1608,7 +1613,7 @@ static void raid1d(mddev_t *mddev)
                                bio->bi_sector = r1_bio->sector + rdev->data_offset;
                                bio->bi_bdev = rdev->bdev;
                                bio->bi_end_io = raid1_end_read_request;
-                               bio->bi_rw = READ;
+                               bio->bi_rw = READ | do_sync;
                                bio->bi_private = r1_bio;
                                unplug = 1;
                                generic_make_request(bio);

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index f0141910bb8d8a0166df17903c977c404057514c..a9401c017e3588f076411d83046c84b27495eab8 100644 (file)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -782,6 +782,7 @@ static int make_request(request_queue_t *q, struct bio * bio)
        int i;
        int chunk_sects = conf->chunk_mask + 1;
        const int rw = bio_data_dir(bio);
+       const int do_sync = bio_sync(bio);
        struct bio_list bl;
        unsigned long flags;
 
@@ -863,7 +864,7 @@ static int make_request(request_queue_t *q, struct bio * bio)
                        mirror->rdev->data_offset;
                read_bio->bi_bdev = mirror->rdev->bdev;
                read_bio->bi_end_io = raid10_end_read_request;
-               read_bio->bi_rw = READ;
+               read_bio->bi_rw = READ | do_sync;
                read_bio->bi_private = r10_bio;
 
                generic_make_request(read_bio);
@@ -909,7 +910,7 @@ static int make_request(request_queue_t *q, struct bio * bio)
                        conf->mirrors[d].rdev->data_offset;
                mbio->bi_bdev = conf->mirrors[d].rdev->bdev;
                mbio->bi_end_io = raid10_end_write_request;
-               mbio->bi_rw = WRITE;
+               mbio->bi_rw = WRITE | do_sync;
                mbio->bi_private = r10_bio;
 
                atomic_inc(&r10_bio->remaining);
@@ -922,6 +923,9 @@ static int make_request(request_queue_t *q, struct bio * bio)
        blk_plug_device(mddev->queue);
        spin_unlock_irqrestore(&conf->device_lock, flags);
 
+       if (do_sync)
+               md_wakeup_thread(mddev->thread);
+
        return 0;
 }
 
@@ -1563,6 +1567,7 @@ static void raid10d(mddev_t *mddev)
                                       (unsigned long long)r10_bio->sector);
                                raid_end_bio_io(r10_bio);
                        } else {
+                               const int do_sync = bio_sync(r10_bio->master_bio);
                                rdev = conf->mirrors[mirror].rdev;
                                if (printk_ratelimit())
                                        printk(KERN_ERR "raid10: %s: redirecting sector %llu to"
@@ -1574,7 +1579,7 @@ static void raid10d(mddev_t *mddev)
                                bio->bi_sector = r10_bio->devs[r10_bio->read_slot].addr
                                        + rdev->data_offset;
                                bio->bi_bdev = rdev->bdev;
-                               bio->bi_rw = READ;
+                               bio->bi_rw = READ | do_sync;
                                bio->bi_private = r10_bio;
                                bio->bi_end_io = raid10_end_read_request;
                                unplug = 1;