From 37011e3afb0fdc462307dc006246358bddf61e92 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Wed, 15 Mar 2017 14:05:14 +1100 Subject: [PATCH] md/raid1: stop using bi_phys_segment 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 Signed-off-by: Shaohua Li --- drivers/md/raid1.c | 89 ++++++++++++---------------------------------- 1 file changed, 23 insertions(+), 66 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 3afa60eb72c5..941f81063891 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -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 { -- 2.20.1