From mboxrd@z Thu Jan 1 00:00:00 1970 From: Song Liu Subject: [PATCH v2] md/r5cache: improve recovery with read ahead page pool Date: Tue, 7 Mar 2017 13:47:01 -0800 Message-ID: <20170307214702.3527217-1-songliubraving@fb.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org Cc: shli@fb.com, neilb@suse.com, kernel-team@fb.com, dan.j.williams@intel.com, hch@infradead.org, Song Liu List-Id: linux-raid.ids In r5cache recovery, the journal device is scanned page by page. Currently, we use sync_page_io() to read journal device. This is not efficient when we have to recovery many stripes from the journal. To improve the speed of recovery, this patch introduces a read ahead page pool (ra_pool) to recovery_ctx. With ra_pool, multiple consecutive pages are read in one IO. Then the recovery code read the journal from ra_pool. With ra_pool, r5l_recovery_ctx has become much bigger. Therefore, r5l_recovery_log() is refactored so r5l_recovery_ctx is not using stack space. Signed-off-by: Song Liu --- drivers/md/raid5-cache.c | 225 +++++++++++++++++++++++++++++++++++++---------- 1 file changed, 178 insertions(+), 47 deletions(-) diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c index 3f307be..73a24ab 100644 --- a/drivers/md/raid5-cache.c +++ b/drivers/md/raid5-cache.c @@ -30,6 +30,7 @@ * underneath hardware sector size. only works with PAGE_SIZE == 4096 */ #define BLOCK_SECTORS (8) +#define BLOCK_SECTOR_SHIFT (3) /* * log->max_free_space is min(1/4 disk size, 10G reclaimable space). @@ -1552,6 +1553,8 @@ bool r5l_log_disk_error(struct r5conf *conf) return ret; } +#define R5L_RECOVERY_PAGE_POOL_SIZE 256 + struct r5l_recovery_ctx { struct page *meta_page; /* current meta */ sector_t meta_total_blocks; /* total size of current meta and data */ @@ -1560,18 +1563,131 @@ struct r5l_recovery_ctx { int data_parity_stripes; /* number of data_parity stripes */ int data_only_stripes; /* number of data_only stripes */ struct list_head cached_list; + + /* + * read ahead page pool (ra_pool) + * in recovery, log is read sequentially. It is not efficient to + * read every page with sync_page_io(). The read ahead page pool + * reads multiple pages with one IO, so further log read can + * just copy data from the pool. + */ + struct page *ra_pool[R5L_RECOVERY_PAGE_POOL_SIZE]; + sector_t pool_offset; /* offset of first page in the pool */ + int total_pages; /* total allocated pages */ + int valid_pages; /* pages with valid data */ + struct bio *ra_bio; /* bio to do the read ahead */ }; +static int r5l_recovery_allocate_ra_pool(struct r5l_log *log, + struct r5l_recovery_ctx *ctx) +{ + struct page *page; + + ctx->ra_bio = bio_alloc_bioset(GFP_KERNEL, BIO_MAX_PAGES, log->bs); + if (!ctx->ra_bio) + return -ENOMEM; + + ctx->valid_pages = 0; + ctx->total_pages = 0; + while (ctx->total_pages < R5L_RECOVERY_PAGE_POOL_SIZE) { + page = alloc_page(GFP_KERNEL); + + if (!page) + break; + ctx->ra_pool[ctx->total_pages] = page; + ctx->total_pages += 1; + } + + if (ctx->total_pages == 0) { + bio_put(ctx->ra_bio); + return -ENOMEM; + } + + ctx->pool_offset = 0; + return 0; +} + +static void r5l_recovery_free_ra_pool(struct r5l_log *log, + struct r5l_recovery_ctx *ctx) +{ + int i; + + for (i = 0; i < ctx->total_pages; ++i) + put_page(ctx->ra_pool[i]); + bio_put(ctx->ra_bio); +} + +/* + * fetch ctx->valid_pages pages from offset + * In normal cases, ctx->valid_pages == ctx->total_pages after the call. + * However, if the offset is close to the end of the journal device, + * ctx->valid_pages could be smaller than ctx->total_pages + */ +static int r5l_recovery_fetch_ra_pool(struct r5l_log *log, + struct r5l_recovery_ctx *ctx, + sector_t offset) +{ + bio_reset(ctx->ra_bio); + ctx->ra_bio->bi_bdev = log->rdev->bdev; + bio_set_op_attrs(ctx->ra_bio, REQ_OP_READ, 0); + ctx->ra_bio->bi_iter.bi_sector = log->rdev->data_offset + offset; + + ctx->valid_pages = 0; + ctx->pool_offset = offset; + + while (ctx->valid_pages < ctx->total_pages) { + bio_add_page(ctx->ra_bio, + ctx->ra_pool[ctx->valid_pages], PAGE_SIZE, 0); + ctx->valid_pages += 1; + + offset = r5l_ring_add(log, offset, BLOCK_SECTORS); + + if (offset == 0) /* reached end of the device */ + break; + } + + return submit_bio_wait(ctx->ra_bio); +} + +/* + * try read a page from the read ahead page pool, if the page is not in the + * pool, call r5l_recovery_fetch_ra_pool + */ +static int r5l_recovery_read_page(struct r5l_log *log, + struct r5l_recovery_ctx *ctx, + struct page *page, + sector_t offset) +{ + int ret; + + if (offset < ctx->pool_offset || + offset >= ctx->pool_offset + ctx->valid_pages * BLOCK_SECTORS) { + ret = r5l_recovery_fetch_ra_pool(log, ctx, offset); + if (ret) + return ret; + } + + BUG_ON(offset < ctx->pool_offset || + offset >= ctx->pool_offset + ctx->valid_pages * BLOCK_SECTORS); + + memcpy(page_address(page), + page_address(ctx->ra_pool[(offset - ctx->pool_offset) >> + BLOCK_SECTOR_SHIFT]), + PAGE_SIZE); + return 0; +} + static int r5l_recovery_read_meta_block(struct r5l_log *log, struct r5l_recovery_ctx *ctx) { struct page *page = ctx->meta_page; struct r5l_meta_block *mb; u32 crc, stored_crc; + int ret; - if (!sync_page_io(log->rdev, ctx->pos, PAGE_SIZE, page, REQ_OP_READ, 0, - false)) - return -EIO; + ret = r5l_recovery_read_page(log, ctx, page, ctx->pos); + if (ret != 0) + return ret; mb = page_address(page); stored_crc = le32_to_cpu(mb->checksum); @@ -1653,8 +1769,7 @@ static void r5l_recovery_load_data(struct r5l_log *log, raid5_compute_sector(conf, le64_to_cpu(payload->location), 0, &dd_idx, sh); - sync_page_io(log->rdev, log_offset, PAGE_SIZE, - sh->dev[dd_idx].page, REQ_OP_READ, 0, false); + r5l_recovery_read_page(log, ctx, sh->dev[dd_idx].page, log_offset); sh->dev[dd_idx].log_checksum = le32_to_cpu(payload->checksum[0]); ctx->meta_total_blocks += BLOCK_SECTORS; @@ -1673,17 +1788,15 @@ static void r5l_recovery_load_parity(struct r5l_log *log, struct r5conf *conf = mddev->private; ctx->meta_total_blocks += BLOCK_SECTORS * conf->max_degraded; - sync_page_io(log->rdev, log_offset, PAGE_SIZE, - sh->dev[sh->pd_idx].page, REQ_OP_READ, 0, false); + r5l_recovery_read_page(log, ctx, sh->dev[sh->pd_idx].page, log_offset); sh->dev[sh->pd_idx].log_checksum = le32_to_cpu(payload->checksum[0]); set_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags); if (sh->qd_idx >= 0) { - sync_page_io(log->rdev, - r5l_ring_add(log, log_offset, BLOCK_SECTORS), - PAGE_SIZE, sh->dev[sh->qd_idx].page, - REQ_OP_READ, 0, false); + r5l_recovery_read_page( + log, ctx, sh->dev[sh->qd_idx].page, + r5l_ring_add(log, log_offset, BLOCK_SECTORS)); sh->dev[sh->qd_idx].log_checksum = le32_to_cpu(payload->checksum[1]); set_bit(R5_Wantwrite, &sh->dev[sh->qd_idx].flags); @@ -1814,14 +1927,15 @@ r5c_recovery_replay_stripes(struct list_head *cached_stripe_list, /* if matches return 0; otherwise return -EINVAL */ static int -r5l_recovery_verify_data_checksum(struct r5l_log *log, struct page *page, +r5l_recovery_verify_data_checksum(struct r5l_log *log, + struct r5l_recovery_ctx *ctx, + struct page *page, sector_t log_offset, __le32 log_checksum) { void *addr; u32 checksum; - sync_page_io(log->rdev, log_offset, PAGE_SIZE, - page, REQ_OP_READ, 0, false); + r5l_recovery_read_page(log, ctx, page, log_offset); addr = kmap_atomic(page); checksum = crc32c_le(log->uuid_checksum, addr, PAGE_SIZE); kunmap_atomic(addr); @@ -1853,17 +1967,17 @@ r5l_recovery_verify_data_checksum_for_mb(struct r5l_log *log, if (payload->header.type == R5LOG_PAYLOAD_DATA) { if (r5l_recovery_verify_data_checksum( - log, page, log_offset, + log, ctx, page, log_offset, payload->checksum[0]) < 0) goto mismatch; } else if (payload->header.type == R5LOG_PAYLOAD_PARITY) { if (r5l_recovery_verify_data_checksum( - log, page, log_offset, + log, ctx, page, log_offset, payload->checksum[0]) < 0) goto mismatch; if (conf->max_degraded == 2 && /* q for RAID 6 */ r5l_recovery_verify_data_checksum( - log, page, + log, ctx, page, r5l_ring_add(log, log_offset, BLOCK_SECTORS), payload->checksum[1]) < 0) @@ -2241,55 +2355,72 @@ static void r5c_recovery_flush_data_only_stripes(struct r5l_log *log, static int r5l_recovery_log(struct r5l_log *log) { struct mddev *mddev = log->rdev->mddev; - struct r5l_recovery_ctx ctx; + struct r5l_recovery_ctx *ctx; int ret; sector_t pos; - ctx.pos = log->last_checkpoint; - ctx.seq = log->last_cp_seq; - ctx.meta_page = alloc_page(GFP_KERNEL); - ctx.data_only_stripes = 0; - ctx.data_parity_stripes = 0; - INIT_LIST_HEAD(&ctx.cached_list); - - if (!ctx.meta_page) + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); + if (!ctx) return -ENOMEM; - ret = r5c_recovery_flush_log(log, &ctx); - __free_page(ctx.meta_page); + ctx->pos = log->last_checkpoint; + ctx->seq = log->last_cp_seq; + ctx->data_only_stripes = 0; + ctx->data_parity_stripes = 0; + INIT_LIST_HEAD(&ctx->cached_list); + ctx->meta_page = alloc_page(GFP_KERNEL); - if (ret) - return ret; + if (!ctx->meta_page) { + ret = -ENOMEM; + goto meta_page; + } + + if (r5l_recovery_allocate_ra_pool(log, ctx) != 0) { + ret = -ENOMEM; + goto ra_pool; + } - pos = ctx.pos; - ctx.seq += 10000; + ret = r5c_recovery_flush_log(log, ctx); + if (ret) + goto error; - if ((ctx.data_only_stripes == 0) && (ctx.data_parity_stripes == 0)) + pos = ctx->pos; + ctx->seq += 10000; + + if ((ctx->data_only_stripes == 0) && (ctx->data_parity_stripes == 0)) pr_debug("md/raid:%s: starting from clean shutdown\n", mdname(mddev)); else - pr_debug("md/raid:%s: recovering %d data-only stripes and %d data-parity stripes\n", - mdname(mddev), ctx.data_only_stripes, - ctx.data_parity_stripes); - - if (ctx.data_only_stripes == 0) { - log->next_checkpoint = ctx.pos; - r5l_log_write_empty_meta_block(log, ctx.pos, ctx.seq++); - ctx.pos = r5l_ring_add(log, ctx.pos, BLOCK_SECTORS); - } else if (r5c_recovery_rewrite_data_only_stripes(log, &ctx)) { + pr_info("md/raid:%s: recovering %d data-only stripes and %d data-parity stripes\n", + mdname(mddev), ctx->data_only_stripes, + ctx->data_parity_stripes); + + if (ctx->data_only_stripes == 0) { + log->next_checkpoint = ctx->pos; + r5l_log_write_empty_meta_block(log, ctx->pos, ctx->seq++); + ctx->pos = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS); + } else if (r5c_recovery_rewrite_data_only_stripes(log, ctx)) { pr_err("md/raid:%s: failed to rewrite stripes to journal\n", mdname(mddev)); - return -EIO; + ret = -EIO; + goto error; } - log->log_start = ctx.pos; - log->seq = ctx.seq; + log->log_start = ctx->pos; + log->seq = ctx->seq; log->last_checkpoint = pos; r5l_write_super(log, pos); - r5c_recovery_flush_data_only_stripes(log, &ctx); - return 0; + r5c_recovery_flush_data_only_stripes(log, ctx); + ret = 0; +error: + r5l_recovery_free_ra_pool(log, ctx); +ra_pool: + __free_page(ctx->meta_page); +meta_page: + kfree(ctx); + return ret; } static void r5l_write_super(struct r5l_log *log, sector_t cp) -- 2.9.3