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md/raid10: improve discard request for far layout

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For far layout, the discard region is not continuous on disks. So it needs
far copies r10bio to cover all regions. It needs a way to know all r10bios
have finish or not. Similar with raid10_sync_request, only the first r10bio
master_bio records the discard bio. Other r10bios master_bio record the
first r10bio. The first r10bio can finish after other r10bios finish and
then return the discard bio.

Signed-off-by: Xiao Ni <xni@redhat.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
This commit is contained in:
Xiao Ni 2020-09-02 20:00:23 +08:00 committed by Song Liu
parent bcc90d2804
commit d3ee2d8415
2 changed files with 64 additions and 23 deletions
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86
drivers/md/raid10.c
View File

@ -1534,6 +1534,28 @@ static struct bio *raid10_split_bio(struct r10conf *conf,
return bio;
}
static void raid_end_discard_bio(struct r10bio *r10bio)
{
struct r10conf *conf = r10bio->mddev->private;
struct r10bio *first_r10bio;
while (atomic_dec_and_test(&r10bio->remaining)) {
allow_barrier(conf);
if (!test_bit(R10BIO_Discard, &r10bio->state)) {
first_r10bio = (struct r10bio *)r10bio->master_bio;
free_r10bio(r10bio);
r10bio = first_r10bio;
} else {
md_write_end(r10bio->mddev);
bio_endio(r10bio->master_bio);
free_r10bio(r10bio);
break;
}
}
}
static void raid10_end_discard_request(struct bio *bio)
{
struct r10bio *r10_bio = bio->bi_private;
@ -1560,11 +1582,7 @@ static void raid10_end_discard_request(struct bio *bio)
rdev = conf->mirrors[dev].rdev;
}
if (atomic_dec_and_test(&r10_bio->remaining)) {
md_write_end(r10_bio->mddev);
raid_end_bio_io(r10_bio);
}
raid_end_discard_bio(r10_bio);
rdev_dec_pending(rdev, conf->mddev);
}
@ -1577,7 +1595,9 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
{
struct r10conf *conf = mddev->private;
struct geom *geo = &conf->geo;
struct r10bio *r10_bio;
struct r10bio *r10_bio, *first_r10bio;
int far_copies = geo->far_copies;
bool first_copy = true;
int disk;
sector_t chunk;
@ -1616,30 +1636,20 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
if (bio_sectors(bio) < stripe_size*2)
goto out;
/* For far offset layout, if bio is not aligned with stripe size, it splits
* the part that is not aligned with strip size.
/* For far and far offset layout, if bio is not aligned with stripe size,
* it splits the part that is not aligned with strip size.
*/
div_u64_rem(bio_start, stripe_size, &remainder);
if (geo->far_offset && remainder) {
if ((far_copies > 1) && remainder) {
split_size = stripe_size - remainder;
bio = raid10_split_bio(conf, bio, split_size, false);
}
div_u64_rem(bio_end, stripe_size, &remainder);
if (geo->far_offset && remainder) {
if ((far_copies > 1) && remainder) {
split_size = bio_sectors(bio) - remainder;
bio = raid10_split_bio(conf, bio, split_size, true);
}
r10_bio = mempool_alloc(&conf->r10bio_pool, GFP_NOIO);
r10_bio->mddev = mddev;
r10_bio->state = 0;
r10_bio->sectors = 0;
memset(r10_bio->devs, 0, sizeof(r10_bio->devs[0]) * geo->raid_disks);
wait_blocked_dev(mddev, r10_bio);
r10_bio->master_bio = bio;
bio_start = bio->bi_iter.bi_sector;
bio_end = bio_end_sector(bio);
@ -1665,6 +1675,28 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
end_disk_offset = (bio_end & geo->chunk_mask) +
(last_stripe_index << geo->chunk_shift);
retry_discard:
r10_bio = mempool_alloc(&conf->r10bio_pool, GFP_NOIO);
r10_bio->mddev = mddev;
r10_bio->state = 0;
r10_bio->sectors = 0;
memset(r10_bio->devs, 0, sizeof(r10_bio->devs[0]) * geo->raid_disks);
wait_blocked_dev(mddev, r10_bio);
/* For far layout it needs more than one r10bio to cover all regions.
* Inspired by raid10_sync_request, we can use the first r10bio->master_bio
* to record the discard bio. Other r10bio->master_bio record the first
* r10bio. The first r10bio only release after all other r10bios finish.
* The discard bio returns only first r10bio finishes
*/
if (first_copy) {
r10_bio->master_bio = bio;
set_bit(R10BIO_Discard, &r10_bio->state);
first_copy = false;
first_r10bio = r10_bio;
} else
r10_bio->master_bio = (struct bio *)first_r10bio;
rcu_read_lock();
for (disk = 0; disk < geo->raid_disks; disk++) {
struct md_rdev *rdev = rcu_dereference(conf->mirrors[disk].rdev);
@ -1755,11 +1787,19 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
}
}
if (atomic_dec_and_test(&r10_bio->remaining)) {
md_write_end(r10_bio->mddev);
raid_end_bio_io(r10_bio);
if (!geo->far_offset && --far_copies) {
first_stripe_index += geo->stride >> geo->chunk_shift;
start_disk_offset += geo->stride;
last_stripe_index += geo->stride >> geo->chunk_shift;
end_disk_offset += geo->stride;
atomic_inc(&first_r10bio->remaining);
raid_end_discard_bio(r10_bio);
wait_barrier(conf);
goto retry_discard;
}
raid_end_discard_bio(r10_bio);
return 0;
out:
allow_barrier(conf);

1
drivers/md/raid10.h
View File

@ -179,5 +179,6 @@ enum r10bio_state {
R10BIO_Previous,
/* failfast devices did receive failfast requests. */
R10BIO_FailFast,
R10BIO_Discard,
};
#endif