From 016c76ac76e4c678b01a75a602dc6be0282f5b29 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Wed, 15 Mar 2017 14:05:13 +1100 Subject: [PATCH] md/raid5: use bio_inc_remaining() instead of repurposing bi_phys_segments as a counter md/raid5 needs to keep track of how many stripe_heads are processing a bio so that it can delay calling bio_endio() until all stripe_heads have completed. It currently uses 16 bits of ->bi_phys_segments for this purpose. 16 bits is only enough for 256M requests, and it is possible for a single bio to be larger than this, which causes problems. Also, the bio struct contains a larger counter, __bi_remaining, which has a purpose very similar to the purpose of our counter. So stop using ->bi_phys_segments, and instead use __bi_remaining. This means we don't need to initialize the counter, as our caller initializes it to '1'. It also means we can call bio_endio() directly as it tests this counter internally. Signed-off-by: NeilBrown Signed-off-by: Shaohua Li --- drivers/md/raid5-cache.c | 3 +-- drivers/md/raid5.c | 57 +++++++++------------------------------- drivers/md/raid5.h | 17 +----------- 3 files changed, 15 insertions(+), 62 deletions(-) diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c index 5be8dbc5d91b..25eb048298fe 100644 --- a/drivers/md/raid5-cache.c +++ b/drivers/md/raid5-cache.c @@ -318,8 +318,7 @@ r5c_return_dev_pending_writes(struct r5conf *conf, struct r5dev *dev) dev->sector + STRIPE_SECTORS) { wbi2 = r5_next_bio(wbi, dev->sector); md_write_end(conf->mddev); - if (!raid5_dec_bi_active_stripes(wbi)) - bio_endio(wbi); + bio_endio(wbi); wbi = wbi2; } } diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 44c8ceba13fe..0ec9e0212158 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -1322,8 +1322,7 @@ static void ops_complete_biofill(void *stripe_head_ref) while (rbi && rbi->bi_iter.bi_sector < dev->sector + STRIPE_SECTORS) { rbi2 = r5_next_bio(rbi, dev->sector); - if (!raid5_dec_bi_active_stripes(rbi)) - bio_endio(rbi); + bio_endio(rbi); rbi = rbi2; } } @@ -3196,14 +3195,6 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, (unsigned long long)bi->bi_iter.bi_sector, (unsigned long long)sh->sector); - /* - * If several bio share a stripe. The bio bi_phys_segments acts as a - * reference count to avoid race. The reference count should already be - * increased before this function is called (for example, in - * raid5_make_request()), so other bio sharing this stripe will not free the - * stripe. If a stripe is owned by one stripe, the stripe lock will - * protect it. - */ spin_lock_irq(&sh->stripe_lock); /* Don't allow new IO added to stripes in batch list */ if (sh->batch_head) @@ -3259,7 +3250,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, if (*bip) bi->bi_next = *bip; *bip = bi; - raid5_inc_bi_active_stripes(bi); + bio_inc_remaining(bi); md_write_inc(conf->mddev, bi); if (forwrite) { @@ -3384,8 +3375,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh, bi->bi_error = -EIO; md_write_end(conf->mddev); - if (!raid5_dec_bi_active_stripes(bi)) - bio_endio(bi); + bio_endio(bi); bi = nextbi; } if (bitmap_end) @@ -3407,8 +3397,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh, bi->bi_error = -EIO; md_write_end(conf->mddev); - if (!raid5_dec_bi_active_stripes(bi)) - bio_endio(bi); + bio_endio(bi); bi = bi2; } @@ -3433,8 +3422,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh, r5_next_bio(bi, sh->dev[i].sector); bi->bi_error = -EIO; - if (!raid5_dec_bi_active_stripes(bi)) - bio_endio(bi); + bio_endio(bi); bi = nextbi; } } @@ -3766,8 +3754,7 @@ returnbi: dev->sector + STRIPE_SECTORS) { wbi2 = r5_next_bio(wbi, dev->sector); md_write_end(conf->mddev); - if (!raid5_dec_bi_active_stripes(wbi)) - bio_endio(wbi); + bio_endio(wbi); wbi = wbi2; } bitmap_endwrite(conf->mddev->bitmap, sh->sector, @@ -5112,7 +5099,7 @@ static struct bio *remove_bio_from_retry(struct r5conf *conf) * this sets the active strip count to 1 and the processed * strip count to zero (upper 8 bits) */ - raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */ + raid5_set_bi_processed_stripes(bi, 0); } return bi; @@ -5449,7 +5436,6 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi) struct r5conf *conf = mddev->private; sector_t logical_sector, last_sector; struct stripe_head *sh; - int remaining; int stripe_sectors; if (mddev->reshape_position != MaxSector) @@ -5460,7 +5446,6 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi) last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9); 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 * @@ -5507,7 +5492,7 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi) continue; sh->dev[d].towrite = bi; set_bit(R5_OVERWRITE, &sh->dev[d].flags); - raid5_inc_bi_active_stripes(bi); + bio_inc_remaining(bi); md_write_inc(mddev, bi); sh->overwrite_disks++; } @@ -5532,10 +5517,7 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi) } md_write_end(mddev); - remaining = raid5_dec_bi_active_stripes(bi); - if (remaining == 0) { - bio_endio(bi); - } + bio_endio(bi); } static void raid5_make_request(struct mddev *mddev, struct bio * bi) @@ -5546,7 +5528,6 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi) sector_t logical_sector, last_sector; struct stripe_head *sh; const int rw = bio_data_dir(bi); - int remaining; DEFINE_WAIT(w); bool do_prepare; bool do_flush = false; @@ -5588,7 +5569,6 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi) logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1); 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); @@ -5726,14 +5706,7 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi) if (rw == WRITE) md_write_end(mddev); - remaining = raid5_dec_bi_active_stripes(bi); - if (remaining == 0) { - - - trace_block_bio_complete(bdev_get_queue(bi->bi_bdev), - bi, 0); - bio_endio(bi); - } + bio_endio(bi); } static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks); @@ -6098,7 +6071,6 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio) int dd_idx; sector_t sector, logical_sector, last_sector; int scnt = 0; - int remaining; int handled = 0; logical_sector = raid_bio->bi_iter.bi_sector & @@ -6137,12 +6109,9 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio) raid5_release_stripe(sh); handled++; } - remaining = raid5_dec_bi_active_stripes(raid_bio); - if (remaining == 0) { - trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev), - raid_bio, 0); - bio_endio(raid_bio); - } + + bio_endio(raid_bio); + if (atomic_dec_and_test(&conf->active_aligned_reads)) wake_up(&conf->wait_for_quiescent); return handled; diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h index fd5c21cde77f..7d74fb3f2ec6 100644 --- a/drivers/md/raid5.h +++ b/drivers/md/raid5.h @@ -488,8 +488,7 @@ static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector) } /* - * We maintain a biased count of active stripes in the bottom 16 bits of - * bi_phys_segments, and a count of processed stripes in the upper 16 bits + * We maintain a count of processed stripes in the upper 16 bits */ static inline int raid5_bi_processed_stripes(struct bio *bio) { @@ -498,20 +497,6 @@ static inline int raid5_bi_processed_stripes(struct bio *bio) return (atomic_read(segments) >> 16) & 0xffff; } -static inline int raid5_dec_bi_active_stripes(struct bio *bio) -{ - atomic_t *segments = (atomic_t *)&bio->bi_phys_segments; - - return atomic_sub_return(1, segments) & 0xffff; -} - -static inline void raid5_inc_bi_active_stripes(struct bio *bio) -{ - atomic_t *segments = (atomic_t *)&bio->bi_phys_segments; - - atomic_inc(segments); -} - static inline void raid5_set_bi_processed_stripes(struct bio *bio, unsigned int cnt) { -- 2.30.2