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md/raid1: stop using bi_phys_segment

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Change to use bio->__bi_remaining to count number of r1bio attached
to a bio.
See precious raid10 patch for more details.

Like the raid10.c patch, this fixes a bug as nr_queued and nr_pending
used to measure different things, but were being compared.

This patch fixes another bug in that nr_pending previously did not
could write-behind requests, so behind writes could continue while
resync was happening.  How that nr_pending counts all r1_bio,
the resync cannot commence until the behind writes have completed.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
NeilBrown 2017-03-15 14:05:14 +11:00 committed by Shaohua Li
parent fd16f2e848
commit 37011e3afb
1 changed files with 23 additions and 66 deletions
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89
drivers/md/raid1.c
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@ -246,35 +246,17 @@ static void reschedule_retry(struct r1bio *r1_bio)
static void call_bio_endio(struct r1bio *r1_bio)
{
struct bio *bio = r1_bio->master_bio;
int done;
struct r1conf *conf = r1_bio->mddev->private;
sector_t bi_sector = bio->bi_iter.bi_sector;
if (bio->bi_phys_segments) {
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
bio->bi_phys_segments--;
done = (bio->bi_phys_segments == 0);
spin_unlock_irqrestore(&conf->device_lock, flags);
/*
* make_request() might be waiting for
* bi_phys_segments to decrease
*/
wake_up(&conf->wait_barrier);
} else
done = 1;
if (!test_bit(R1BIO_Uptodate, &r1_bio->state))
bio->bi_error = -EIO;
if (done) {
bio_endio(bio);
/*
* Wake up any possible resync thread that waits for the device
* to go idle.
*/
allow_barrier(conf, bi_sector);
}
bio_endio(bio);
/*
* Wake up any possible resync thread that waits for the device
* to go idle.
*/
allow_barrier(conf, r1_bio->sector);
}
static void raid_end_bio_io(struct r1bio *r1_bio)
@ -977,6 +959,16 @@ static void wait_read_barrier(struct r1conf *conf, sector_t sector_nr)
spin_unlock_irq(&conf->resync_lock);
}
static void inc_pending(struct r1conf *conf, sector_t bi_sector)
{
/* The current request requires multiple r1_bio, so
* we need to increment the pending count, and the corresponding
* window count.
*/
int idx = sector_to_idx(bi_sector);
atomic_inc(&conf->nr_pending[idx]);
}
static void wait_barrier(struct r1conf *conf, sector_t sector_nr)
{
int idx = sector_to_idx(sector_nr);
@ -1191,17 +1183,6 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio)
r1_bio = alloc_r1bio(mddev, bio, 0);
/*
* We might need to issue multiple reads to different
* devices if there are bad blocks around, so we keep
* track of the number of reads in bio->bi_phys_segments.
* If this is 0, there is only one r1_bio and no locking
* will be needed when requests complete. If it is
* non-zero, then it is the number of not-completed requests.
*/
bio->bi_phys_segments = 0;
bio_clear_flag(bio, BIO_SEG_VALID);
/*
* make_request() can abort the operation when read-ahead is being
* used and no empty request is available.
@ -1257,12 +1238,7 @@ read_again:
sectors_handled = (r1_bio->sector + max_sectors
- bio->bi_iter.bi_sector);
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);
bio_inc_remaining(bio);
/*
* Cannot call generic_make_request directly as that will be
@ -1329,16 +1305,6 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio)
r1_bio = alloc_r1bio(mddev, bio, 0);
/* We might need to issue multiple writes to different
* devices if there are bad blocks around, so we keep
* track of the number of writes in bio->bi_phys_segments.
* If this is 0, there is only one r1_bio and no locking
* will be needed when requests complete. If it is
* non-zero, then it is the number of not-completed requests.
*/
bio->bi_phys_segments = 0;
bio_clear_flag(bio, BIO_SEG_VALID);
if (conf->pending_count >= max_queued_requests) {
md_wakeup_thread(mddev->thread);
raid1_log(mddev, "wait queued");
@ -1544,16 +1510,11 @@ 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)) {
/* 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);
/* We need another r1_bio, which must be counted */
sector_t sect = bio->bi_iter.bi_sector + sectors_handled;
inc_pending(conf, sect);
bio_inc_remaining(bio);
r1_bio_write_done(r1_bio);
r1_bio = alloc_r1bio(mddev, bio, sectors_handled);
goto retry_write;
@ -2573,12 +2534,7 @@ read_more:
int sectors_handled = (r1_bio->sector + max_sectors
- mbio->bi_iter.bi_sector);
r1_bio->sectors = max_sectors;
spin_lock_irq(&conf->device_lock);
if (mbio->bi_phys_segments == 0)
mbio->bi_phys_segments = 2;
else
mbio->bi_phys_segments++;
spin_unlock_irq(&conf->device_lock);
bio_inc_remaining(mbio);
trace_block_bio_remap(bdev_get_queue(bio->bi_bdev),
bio, bio_dev, bio_sector);
generic_make_request(bio);
@ -2586,6 +2542,7 @@ read_more:
r1_bio = alloc_r1bio(mddev, mbio, sectors_handled);
set_bit(R1BIO_ReadError, &r1_bio->state);
inc_pending(conf, r1_bio->sector);
goto read_more;
} else {