From 497280509f32340d90feac030bce18006a3e3605 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Wed, 15 Mar 2017 14:05:12 +1100 Subject: md/raid5: use md_write_start to count stripes, not bios We use md_write_start() to increase the count of pending writes, and md_write_end() to decrement the count. We currently count bios submitted to md/raid5. Change it count stripe_heads that a WRITE bio has been attached to. So now, raid5_make_request() calls md_write_start() and then md_write_end() to keep the count elevated during the setup of the request. add_stripe_bio() calls md_write_start() for each stripe_head, and the completion routines always call md_write_end(), instead of only calling it when raid5_dec_bi_active_stripes() returns 0. make_discard_request also calls md_write_start/end(). The parallel between md_write_{start,end} and use of bi_phys_segments can be seen in that: Whenever we set bi_phys_segments to 1, we now call md_write_start. Whenever we increment it on non-read requests with raid5_inc_bi_active_stripes(), we now call md_write_start(). Whenever we decrement bi_phys_segments on non-read requsts with raid5_dec_bi_active_stripes(), we now call md_write_end(). This reduces our dependence on keeping a per-bio count of active stripes in bi_phys_segments. md_write_inc() is added which parallels md_write_start(), but requires that a write has already been started, and is certain never to sleep. This can be used inside a spinlocked region when adding to a write request. Signed-off-by: NeilBrown Signed-off-by: Shaohua Li --- drivers/md/raid5.c | 27 +++++++++++++-------------- 1 file changed, 13 insertions(+), 14 deletions(-) (limited to 'drivers/md/raid5.c') diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 88cc8981bd49..a684003fc965 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -3274,6 +3274,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, bi->bi_next = *bip; *bip = bi; raid5_inc_bi_active_stripes(bi); + md_write_inc(conf->mddev, bi); if (forwrite) { /* check if page is covered */ @@ -3397,10 +3398,9 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh, struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector); bi->bi_error = -EIO; - if (!raid5_dec_bi_active_stripes(bi)) { - md_write_end(conf->mddev); + md_write_end(conf->mddev); + if (!raid5_dec_bi_active_stripes(bi)) bio_list_add(return_bi, bi); - } bi = nextbi; } if (bitmap_end) @@ -3421,10 +3421,9 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh, struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector); bi->bi_error = -EIO; - if (!raid5_dec_bi_active_stripes(bi)) { - md_write_end(conf->mddev); + md_write_end(conf->mddev); + if (!raid5_dec_bi_active_stripes(bi)) bio_list_add(return_bi, bi); - } bi = bi2; } @@ -3781,10 +3780,9 @@ returnbi: while (wbi && wbi->bi_iter.bi_sector < dev->sector + STRIPE_SECTORS) { wbi2 = r5_next_bio(wbi, dev->sector); - if (!raid5_dec_bi_active_stripes(wbi)) { - md_write_end(conf->mddev); + md_write_end(conf->mddev); + if (!raid5_dec_bi_active_stripes(wbi)) bio_list_add(return_bi, wbi); - } wbi = wbi2; } bitmap_endwrite(conf->mddev->bitmap, sh->sector, @@ -5487,6 +5485,7 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi) bi->bi_next = NULL; bi->bi_phys_segments = 1; /* over-loaded to count active stripes */ + md_write_start(mddev, bi); stripe_sectors = conf->chunk_sectors * (conf->raid_disks - conf->max_degraded); @@ -5533,6 +5532,7 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi) sh->dev[d].towrite = bi; set_bit(R5_OVERWRITE, &sh->dev[d].flags); raid5_inc_bi_active_stripes(bi); + md_write_inc(mddev, bi); sh->overwrite_disks++; } spin_unlock_irq(&sh->stripe_lock); @@ -5555,9 +5555,9 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi) release_stripe_plug(mddev, sh); } + md_write_end(mddev); remaining = raid5_dec_bi_active_stripes(bi); if (remaining == 0) { - md_write_end(mddev); bio_endio(bi); } } @@ -5592,8 +5592,6 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi) do_flush = bi->bi_opf & REQ_PREFLUSH; } - md_write_start(mddev, bi); - /* * If array is degraded, better not do chunk aligned read because * later we might have to read it again in order to reconstruct @@ -5615,6 +5613,7 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi) last_sector = bio_end_sector(bi); bi->bi_next = NULL; bi->bi_phys_segments = 1; /* over-loaded to count active stripes */ + md_write_start(mddev, bi); prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE); for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) { @@ -5749,11 +5748,11 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi) } finish_wait(&conf->wait_for_overlap, &w); + if (rw == WRITE) + md_write_end(mddev); remaining = raid5_dec_bi_active_stripes(bi); if (remaining == 0) { - if ( rw == WRITE ) - md_write_end(mddev); trace_block_bio_complete(bdev_get_queue(bi->bi_bdev), bi, 0); -- cgit v1.2.3