From 0472a42ba1f89ec85f070c731f4440d7cc38c44c Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Wed, 15 Mar 2017 14:05:13 +1100 Subject: md/raid5: remove over-loading of ->bi_phys_segments. When a read request, which bypassed the cache, fails, we need to retry it through the cache. This involves attaching it to a sequence of stripe_heads, and it may not be possible to get all the stripe_heads we need at once. We do what we can, and record how far we got in ->bi_phys_segments so we can pick up again later. There is only ever one bio which may have a non-zero offset stored in ->bi_phys_segments, the one that is either active in the single thread which calls retry_aligned_read(), or is in conf->retry_read_aligned waiting for retry_aligned_read() to be called again. So we only need to store one offset value. This can be in a local variable passed between remove_bio_from_retry() and retry_aligned_read(), or in the r5conf structure next to the ->retry_read_aligned pointer. Storing it there allows the last usage of ->bi_phys_segments to be removed from md/raid5.c. Signed-off-by: NeilBrown Signed-off-by: Shaohua Li --- drivers/md/raid5.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) (limited to 'drivers/md/raid5.c') diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 0ec9e0212158..1c8be667e9a9 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -5082,12 +5082,14 @@ static void add_bio_to_retry(struct bio *bi,struct r5conf *conf) md_wakeup_thread(conf->mddev->thread); } -static struct bio *remove_bio_from_retry(struct r5conf *conf) +static struct bio *remove_bio_from_retry(struct r5conf *conf, + unsigned int *offset) { struct bio *bi; bi = conf->retry_read_aligned; if (bi) { + *offset = conf->retry_read_offset; conf->retry_read_aligned = NULL; return bi; } @@ -5095,11 +5097,7 @@ static struct bio *remove_bio_from_retry(struct r5conf *conf) if(bi) { conf->retry_read_aligned_list = bi->bi_next; bi->bi_next = NULL; - /* - * this sets the active strip count to 1 and the processed - * strip count to zero (upper 8 bits) - */ - raid5_set_bi_processed_stripes(bi, 0); + *offset = 0; } return bi; @@ -6055,7 +6053,8 @@ static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_n return STRIPE_SECTORS; } -static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio) +static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio, + unsigned int offset) { /* We may not be able to submit a whole bio at once as there * may not be enough stripe_heads available. @@ -6084,7 +6083,7 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio) sector += STRIPE_SECTORS, scnt++) { - if (scnt < raid5_bi_processed_stripes(raid_bio)) + if (scnt < offset) /* already done this stripe */ continue; @@ -6092,15 +6091,15 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio) if (!sh) { /* failed to get a stripe - must wait */ - raid5_set_bi_processed_stripes(raid_bio, scnt); conf->retry_read_aligned = raid_bio; + conf->retry_read_offset = scnt; return handled; } if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) { raid5_release_stripe(sh); - raid5_set_bi_processed_stripes(raid_bio, scnt); conf->retry_read_aligned = raid_bio; + conf->retry_read_offset = scnt; return handled; } @@ -6228,6 +6227,7 @@ static void raid5d(struct md_thread *thread) while (1) { struct bio *bio; int batch_size, released; + unsigned int offset; released = release_stripe_list(conf, conf->temp_inactive_list); if (released) @@ -6245,10 +6245,10 @@ static void raid5d(struct md_thread *thread) } raid5_activate_delayed(conf); - while ((bio = remove_bio_from_retry(conf))) { + while ((bio = remove_bio_from_retry(conf, &offset))) { int ok; spin_unlock_irq(&conf->device_lock); - ok = retry_aligned_read(conf, bio); + ok = retry_aligned_read(conf, bio, offset); spin_lock_irq(&conf->device_lock); if (!ok) break; -- cgit v1.2.3