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md/raid10: simplify the splitting of requests. 

raid10 splits requests in two different ways for two different
reasons.

First, bio_split() is used to ensure the bio fits with a chunk.
Second, multiple r10bio structures are allocated to represent the
different sections that need to go to different devices, to avoid
known bad blocks.

This can be simplified to just use bio_split() once, and not to use
multiple r10bios.
We delay the split until we know a maximum bio size that can
be handled with a single r10bio, and then split the bio and queue
the remainder for later handling.

As with raid1, we allocate a new bio_set to help with the splitting.
It is not correct to use fs_bio_set in a device driver.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
NeilBrown 2017-04-05 14:05:51 +10:00 коммит произвёл Shaohua Li
Родитель 673ca68d93
Коммит fc9977dd06
2 изменённых файлов: 51 добавлений и 114 удалений
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146
drivers/md/raid10.c
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@ -1127,7 +1127,6 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
struct bio *read_bio;
const int op = bio_op(bio);
const unsigned long do_sync = (bio->bi_opf & REQ_SYNC);
int sectors_handled;
int max_sectors;
sector_t sectors;
struct md_rdev *rdev;
@ -1140,7 +1139,7 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
*/
wait_barrier(conf);
sectors = bio_sectors(bio);
sectors = r10_bio->sectors;
while (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
bio->bi_iter.bi_sector < conf->reshape_progress &&
bio->bi_iter.bi_sector + sectors > conf->reshape_progress) {
@ -1157,17 +1156,23 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
wait_barrier(conf);
}
read_again:
rdev = read_balance(conf, r10_bio, &max_sectors);
if (!rdev) {
raid_end_bio_io(r10_bio);
return;
}
if (max_sectors < bio_sectors(bio)) {
struct bio *split = bio_split(bio, max_sectors,
GFP_NOIO, conf->bio_split);
bio_chain(split, bio);
generic_make_request(bio);
bio = split;
r10_bio->master_bio = bio;
r10_bio->sectors = max_sectors;
}
slot = r10_bio->read_slot;
read_bio = bio_clone_fast(bio, GFP_NOIO, mddev->bio_set);
bio_trim(read_bio, r10_bio->sector - bio->bi_iter.bi_sector,
max_sectors);
r10_bio->devs[slot].bio = read_bio;
r10_bio->devs[slot].rdev = rdev;
@ -1186,40 +1191,13 @@ read_again:
trace_block_bio_remap(bdev_get_queue(read_bio->bi_bdev),
read_bio, disk_devt(mddev->gendisk),
r10_bio->sector);
if (max_sectors < r10_bio->sectors) {
/*
* Could not read all from this device, so we will need another
* r10_bio.
*/
sectors_handled = (r10_bio->sector + max_sectors
- bio->bi_iter.bi_sector);
r10_bio->sectors = max_sectors;
inc_pending(conf);
bio_inc_remaining(bio);
/*
* Cannot call generic_make_request directly as that will be
* queued in __generic_make_request and subsequent
* mempool_alloc might block waiting for it. so hand bio over
* to raid10d.
*/
reschedule_retry(r10_bio);
r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
r10_bio->master_bio = bio;
r10_bio->sectors = bio_sectors(bio) - sectors_handled;
r10_bio->state = 0;
r10_bio->mddev = mddev;
r10_bio->sector = bio->bi_iter.bi_sector + sectors_handled;
goto read_again;
} else
generic_make_request(read_bio);
return;
}
static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio,
struct bio *bio, bool replacement,
int n_copy, int max_sectors)
int n_copy)
{
const int op = bio_op(bio);
const unsigned long do_sync = (bio->bi_opf & REQ_SYNC);
@ -1243,7 +1221,6 @@ static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio,
rdev = conf->mirrors[devnum].rdev;
mbio = bio_clone_fast(bio, GFP_NOIO, mddev->bio_set);
bio_trim(mbio, r10_bio->sector - bio->bi_iter.bi_sector, max_sectors);
if (replacement)
r10_bio->devs[n_copy].repl_bio = mbio;
else
@ -1294,7 +1271,6 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
int i;
struct md_rdev *blocked_rdev;
sector_t sectors;
int sectors_handled;
int max_sectors;
md_write_start(mddev, bio);
@ -1306,7 +1282,7 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
*/
wait_barrier(conf);
sectors = bio_sectors(bio);
sectors = r10_bio->sectors;
while (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
bio->bi_iter.bi_sector < conf->reshape_progress &&
bio->bi_iter.bi_sector + sectors > conf->reshape_progress) {
@ -1476,44 +1452,29 @@ retry_write:
if (max_sectors < r10_bio->sectors)
r10_bio->sectors = max_sectors;
sectors_handled = r10_bio->sector + max_sectors -
bio->bi_iter.bi_sector;
if (r10_bio->sectors < bio_sectors(bio)) {
struct bio *split = bio_split(bio, r10_bio->sectors,
GFP_NOIO, conf->bio_split);
bio_chain(split, bio);
generic_make_request(bio);
bio = split;
r10_bio->master_bio = bio;
}
atomic_set(&r10_bio->remaining, 1);
bitmap_startwrite(mddev->bitmap, r10_bio->sector, r10_bio->sectors, 0);
for (i = 0; i < conf->copies; i++) {
if (r10_bio->devs[i].bio)
raid10_write_one_disk(mddev, r10_bio, bio, false,
i, max_sectors);
raid10_write_one_disk(mddev, r10_bio, bio, false, i);
if (r10_bio->devs[i].repl_bio)
raid10_write_one_disk(mddev, r10_bio, bio, true,
i, max_sectors);
}
/* Don't remove the bias on 'remaining' (one_write_done) until
* after checking if we need to go around again.
*/
if (sectors_handled < bio_sectors(bio)) {
/* We need another r10_bio and it needs to be counted */
inc_pending(conf);
bio_inc_remaining(bio);
one_write_done(r10_bio);
r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
r10_bio->master_bio = bio;
r10_bio->sectors = bio_sectors(bio) - sectors_handled;
r10_bio->mddev = mddev;
r10_bio->sector = bio->bi_iter.bi_sector + sectors_handled;
r10_bio->state = 0;
goto retry_write;
raid10_write_one_disk(mddev, r10_bio, bio, true, i);
}
one_write_done(r10_bio);
}
static void __make_request(struct mddev *mddev, struct bio *bio)
static void __make_request(struct mddev *mddev, struct bio *bio, int sectors)
{
struct r10conf *conf = mddev->private;
struct r10bio *r10_bio;
@ -1521,7 +1482,7 @@ static void __make_request(struct mddev *mddev, struct bio *bio)
r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
r10_bio->master_bio = bio;
r10_bio->sectors = bio_sectors(bio);
r10_bio->sectors = sectors;
r10_bio->mddev = mddev;
r10_bio->sector = bio->bi_iter.bi_sector;
@ -1538,54 +1499,26 @@ static void raid10_make_request(struct mddev *mddev, struct bio *bio)
struct r10conf *conf = mddev->private;
sector_t chunk_mask = (conf->geo.chunk_mask & conf->prev.chunk_mask);
int chunk_sects = chunk_mask + 1;
struct bio *split;
int sectors = bio_sectors(bio);
if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
md_flush_request(mddev, bio);
return;
}
do {
/*
* If this request crosses a chunk boundary, we need to split
* it.
*/
if (unlikely((bio->bi_iter.bi_sector & chunk_mask) +
bio_sectors(bio) > chunk_sects
sectors > chunk_sects
&& (conf->geo.near_copies < conf->geo.raid_disks
|| conf->prev.near_copies <
conf->prev.raid_disks))) {
split = bio_split(bio, chunk_sects -
conf->prev.raid_disks)))
sectors = chunk_sects -
(bio->bi_iter.bi_sector &
(chunk_sects - 1)),
GFP_NOIO, fs_bio_set);
bio_chain(split, bio);
} else {
split = bio;
}
/*
* If a bio is splitted, the first part of bio will pass
* barrier but the bio is queued in current->bio_list (see
* generic_make_request). If there is a raise_barrier() called
* here, the second part of bio can't pass barrier. But since
* the first part bio isn't dispatched to underlaying disks
* yet, the barrier is never released, hence raise_barrier will
* alays wait. We have a deadlock.
* Note, this only happens in read path. For write path, the
* first part of bio is dispatched in a schedule() call
* (because of blk plug) or offloaded to raid10d.
* Quitting from the function immediately can change the bio
* order queued in bio_list and avoid the deadlock.
*/
__make_request(mddev, split);
if (split != bio && bio_data_dir(bio) == READ) {
generic_make_request(bio);
break;
}
} while (split != bio);
(chunk_sects - 1));
__make_request(mddev, bio, sectors);
/* In case raid10d snuck in to freeze_array */
wake_up(&conf->wait_barrier);
@ -2873,13 +2806,8 @@ static void raid10d(struct md_thread *thread)
recovery_request_write(mddev, r10_bio);
else if (test_bit(R10BIO_ReadError, &r10_bio->state))
handle_read_error(mddev, r10_bio);
else {
/* just a partial read to be scheduled from a
* separate context
*/
int slot = r10_bio->read_slot;
generic_make_request(r10_bio->devs[slot].bio);
}
else
WARN_ON_ONCE(1);
cond_resched();
if (mddev->sb_flags & ~(1<<MD_SB_CHANGE_PENDING))
@ -3652,6 +3580,10 @@ static struct r10conf *setup_conf(struct mddev *mddev)
if (!conf->r10bio_pool)
goto out;
conf->bio_split = bioset_create(BIO_POOL_SIZE, 0);
if (!conf->bio_split)
goto out;
calc_sectors(conf, mddev->dev_sectors);
if (mddev->reshape_position == MaxSector) {
conf->prev = conf->geo;
@ -3689,6 +3621,8 @@ static struct r10conf *setup_conf(struct mddev *mddev)
mempool_destroy(conf->r10bio_pool);
kfree(conf->mirrors);
safe_put_page(conf->tmppage);
if (conf->bio_split)
bioset_free(conf->bio_split);
kfree(conf);
}
return ERR_PTR(err);
@ -3899,6 +3833,8 @@ static void raid10_free(struct mddev *mddev, void *priv)
kfree(conf->mirrors);
kfree(conf->mirrors_old);
kfree(conf->mirrors_new);
if (conf->bio_split)
bioset_free(conf->bio_split);
kfree(conf);
}

1
drivers/md/raid10.h
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@ -82,6 +82,7 @@ struct r10conf {
mempool_t *r10bio_pool;
mempool_t *r10buf_pool;
struct page *tmppage;
struct bio_set *bio_split;
/* When taking over an array from a different personality, we store
* the new thread here until we fully activate the array.