From 841c1316c7da6199a7df473893c141943991a756 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Fri, 17 Mar 2017 00:12:31 +0800 Subject: [PATCH] md: raid1: improve write behind This patch improve handling of write behind in the following ways: - introduce behind master bio to hold all write behind pages - fast clone bios from behind master bio - avoid to change bvec table directly - use bio_copy_data() and make code more clean Suggested-by: Shaohua Li Signed-off-by: Ming Lei Signed-off-by: Shaohua Li --- drivers/md/raid1.c | 118 +++++++++++++++++++++------------------------ drivers/md/raid1.h | 10 ++-- 2 files changed, 61 insertions(+), 67 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 64bf2005f082..c6a671f13bc0 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -388,12 +388,9 @@ static void close_write(struct r1bio *r1_bio) { /* it really is the end of this request */ if (test_bit(R1BIO_BehindIO, &r1_bio->state)) { - /* free extra copy of the data pages */ - int i = r1_bio->behind_page_count; - while (i--) - safe_put_page(r1_bio->behind_bvecs[i].bv_page); - kfree(r1_bio->behind_bvecs); - r1_bio->behind_bvecs = NULL; + bio_free_pages(r1_bio->behind_master_bio); + bio_put(r1_bio->behind_master_bio); + r1_bio->behind_master_bio = NULL; } /* clear the bitmap if all writes complete successfully */ bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector, @@ -495,6 +492,10 @@ static void raid1_end_write_request(struct bio *bio) } if (behind) { + /* we release behind master bio when all write are done */ + if (r1_bio->behind_master_bio == bio) + to_put = NULL; + if (test_bit(WriteMostly, &rdev->flags)) atomic_dec(&r1_bio->behind_remaining); @@ -1089,39 +1090,46 @@ static void unfreeze_array(struct r1conf *conf) wake_up(&conf->wait_barrier); } -/* duplicate the data pages for behind I/O - */ -static void alloc_behind_pages(struct bio *bio, struct r1bio *r1_bio) +static struct bio *alloc_behind_master_bio(struct r1bio *r1_bio, + struct bio *bio, + int offset, int size) { - int i; - struct bio_vec *bvec; - struct bio_vec *bvecs = kzalloc(bio->bi_vcnt * sizeof(struct bio_vec), - GFP_NOIO); - if (unlikely(!bvecs)) - return; + unsigned vcnt = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; + int i = 0; + struct bio *behind_bio = NULL; + + behind_bio = bio_alloc_mddev(GFP_NOIO, vcnt, r1_bio->mddev); + if (!behind_bio) + goto fail; + + while (i < vcnt && size) { + struct page *page; + int len = min_t(int, PAGE_SIZE, size); + + page = alloc_page(GFP_NOIO); + if (unlikely(!page)) + goto free_pages; + + bio_add_page(behind_bio, page, len, 0); + + size -= len; + i++; + } - bio_for_each_segment_all(bvec, bio, i) { - bvecs[i] = *bvec; - bvecs[i].bv_page = alloc_page(GFP_NOIO); - if (unlikely(!bvecs[i].bv_page)) - goto do_sync_io; - memcpy(kmap(bvecs[i].bv_page) + bvec->bv_offset, - kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len); - kunmap(bvecs[i].bv_page); - kunmap(bvec->bv_page); - } - r1_bio->behind_bvecs = bvecs; - r1_bio->behind_page_count = bio->bi_vcnt; + bio_copy_data_partial(behind_bio, bio, offset, + behind_bio->bi_iter.bi_size); + + r1_bio->behind_master_bio = behind_bio;; set_bit(R1BIO_BehindIO, &r1_bio->state); - return; -do_sync_io: - for (i = 0; i < bio->bi_vcnt; i++) - if (bvecs[i].bv_page) - put_page(bvecs[i].bv_page); - kfree(bvecs); + return behind_bio; + +free_pages: pr_debug("%dB behind alloc failed, doing sync I/O\n", bio->bi_iter.bi_size); + bio_free_pages(behind_bio); +fail: + return behind_bio; } struct raid1_plug_cb { @@ -1457,11 +1465,9 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio) (atomic_read(&bitmap->behind_writes) < mddev->bitmap_info.max_write_behind) && !waitqueue_active(&bitmap->behind_wait)) { - mbio = bio_clone_bioset_partial(bio, GFP_NOIO, - mddev->bio_set, - offset << 9, - max_sectors << 9); - alloc_behind_pages(mbio, r1_bio); + mbio = alloc_behind_master_bio(r1_bio, bio, + offset << 9, + max_sectors << 9); } bitmap_startwrite(bitmap, r1_bio->sector, @@ -1472,26 +1478,17 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio) } if (!mbio) { - if (r1_bio->behind_bvecs) - mbio = bio_clone_bioset_partial(bio, GFP_NOIO, - mddev->bio_set, - offset << 9, - max_sectors << 9); + if (r1_bio->behind_master_bio) + mbio = bio_clone_fast(r1_bio->behind_master_bio, + GFP_NOIO, + mddev->bio_set); else { mbio = bio_clone_fast(bio, GFP_NOIO, mddev->bio_set); bio_trim(mbio, offset, max_sectors); } } - if (r1_bio->behind_bvecs) { - struct bio_vec *bvec; - int j; - - /* - * We trimmed the bio, so _all is legit - */ - bio_for_each_segment_all(bvec, mbio, j) - bvec->bv_page = r1_bio->behind_bvecs[j].bv_page; + if (r1_bio->behind_master_bio) { if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags)) atomic_inc(&r1_bio->behind_remaining); } @@ -2386,18 +2383,11 @@ static int narrow_write_error(struct r1bio *r1_bio, int i) /* Write at 'sector' for 'sectors'*/ if (test_bit(R1BIO_BehindIO, &r1_bio->state)) { - unsigned vcnt = r1_bio->behind_page_count; - struct bio_vec *vec = r1_bio->behind_bvecs; - - while (!vec->bv_page) { - vec++; - vcnt--; - } - - wbio = bio_alloc_mddev(GFP_NOIO, vcnt, mddev); - memcpy(wbio->bi_io_vec, vec, vcnt * sizeof(struct bio_vec)); - - wbio->bi_vcnt = vcnt; + wbio = bio_clone_fast(r1_bio->behind_master_bio, + GFP_NOIO, + mddev->bio_set); + /* We really need a _all clone */ + wbio->bi_iter = (struct bvec_iter){ 0 }; } else { wbio = bio_clone_fast(r1_bio->master_bio, GFP_NOIO, mddev->bio_set); diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h index dd22a37d0d83..4271cd7ac2de 100644 --- a/drivers/md/raid1.h +++ b/drivers/md/raid1.h @@ -153,9 +153,13 @@ struct r1bio { int read_disk; struct list_head retry_list; - /* Next two are only valid when R1BIO_BehindIO is set */ - struct bio_vec *behind_bvecs; - int behind_page_count; + + /* + * When R1BIO_BehindIO is set, we store pages for write behind + * in behind_master_bio. + */ + struct bio *behind_master_bio; + /* * if the IO is in WRITE direction, then multiple bios are used. * We choose the number when they are allocated. -- 2.20.1