From patchwork Wed Jan 18 22:54:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bart Van Assche X-Patchwork-Id: 644929 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A7153C38159 for ; Wed, 18 Jan 2023 22:55:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230103AbjARWzb (ORCPT ); Wed, 18 Jan 2023 17:55:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230117AbjARWzJ (ORCPT ); Wed, 18 Jan 2023 17:55:09 -0500 Received: from mail-pl1-f178.google.com (mail-pl1-f178.google.com [209.85.214.178]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A6D741CAF3; Wed, 18 Jan 2023 14:55:07 -0800 (PST) Received: by mail-pl1-f178.google.com with SMTP id k13so646523plg.0; Wed, 18 Jan 2023 14:55:07 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=M+26zPAsx0x5i6iQb2oS6taz2VZG1SMytES1MLhydQQ=; b=E0pb/q/xBCycmVo4aJO/iY5bs8FJOCij78qdrLMqemSAV4WKbjaZoYoo8bDNYXi9RQ irdQkch0GCDKJ9vH9uLD3Dvb+HwCULzkfgJfSQcuz9irbmi7PQZCmNFQNs2M0c1YxHnX ZpLyOWdJ07ePZ6iMrVM5Xo7dSdWdON5IRfwS9axIb48kA5nT8romWcRTpgKXpO+twrOn GxF2s8eEMDLJQLmaL/v8HzxtiWJ4kMQL8HccYEiBMjlxnFHwiV6IoClTSMjz+ZauCrQ+ XKGHchZ3/DfrbFrRvxUT9x3tmxzEDALeLk15Laodw21EIwYzIIZVvd7fxnnngvLAgii6 0QLw== X-Gm-Message-State: AFqh2kpnzMmhtTJHITY+baeXPKLSZlODe2PMdnSs5lBNiS35oGfAcmPf SKjgLZfsia00nG1NIrESZIM= X-Google-Smtp-Source: AMrXdXtg2xtzs5hTfhGhhJz4zaFkw00+pY9VLqmBG42Eyd7nVvzVPMBByLHKrjzLrsAhG+IVq5n3kg== X-Received: by 2002:a17:902:eb44:b0:194:84eb:290a with SMTP id i4-20020a170902eb4400b0019484eb290amr9346397pli.50.1674082507034; Wed, 18 Jan 2023 14:55:07 -0800 (PST) Received: from bvanassche-linux.mtv.corp.google.com ([2620:15c:211:201:22ae:3ae3:fde6:2308]) by smtp.gmail.com with ESMTPSA id u7-20020a17090341c700b00186e34524e3sm23649466ple.136.2023.01.18.14.55.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Jan 2023 14:55:06 -0800 (PST) From: Bart Van Assche To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, Jaegeuk Kim , Avri Altman , Adrian Hunter , Christoph Hellwig , Ming Lei , Bart Van Assche , Damien Le Moal , Chaitanya Kulkarni Subject: [PATCH v3 7/9] null_blk: Support configuring the maximum segment size Date: Wed, 18 Jan 2023 14:54:45 -0800 Message-Id: <20230118225447.2809787-8-bvanassche@acm.org> X-Mailer: git-send-email 2.39.0.246.g2a6d74b583-goog In-Reply-To: <20230118225447.2809787-1-bvanassche@acm.org> References: <20230118225447.2809787-1-bvanassche@acm.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Add support for configuring the maximum segment size. Add support for segments smaller than the page size. This patch enables testing segments smaller than the page size with a driver that does not call blk_rq_map_sg(). Cc: Christoph Hellwig Cc: Ming Lei Cc: Damien Le Moal Cc: Chaitanya Kulkarni Signed-off-by: Bart Van Assche --- drivers/block/null_blk/main.c | 21 ++++++++++++++++++--- drivers/block/null_blk/null_blk.h | 1 + 2 files changed, 19 insertions(+), 3 deletions(-) diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c index 4c601ca9552a..822890d89427 100644 --- a/drivers/block/null_blk/main.c +++ b/drivers/block/null_blk/main.c @@ -157,6 +157,10 @@ static int g_max_sectors; module_param_named(max_sectors, g_max_sectors, int, 0444); MODULE_PARM_DESC(max_sectors, "Maximum size of a command (in 512B sectors)"); +static unsigned int g_max_segment_size = BLK_MAX_SEGMENT_SIZE; +module_param_named(max_segment_size, g_max_segment_size, int, 0444); +MODULE_PARM_DESC(max_segment_size, "Maximum size of a segment in bytes"); + static unsigned int nr_devices = 1; module_param(nr_devices, uint, 0444); MODULE_PARM_DESC(nr_devices, "Number of devices to register"); @@ -409,6 +413,7 @@ NULLB_DEVICE_ATTR(home_node, uint, NULL); NULLB_DEVICE_ATTR(queue_mode, uint, NULL); NULLB_DEVICE_ATTR(blocksize, uint, NULL); NULLB_DEVICE_ATTR(max_sectors, uint, NULL); +NULLB_DEVICE_ATTR(max_segment_size, uint, NULL); NULLB_DEVICE_ATTR(irqmode, uint, NULL); NULLB_DEVICE_ATTR(hw_queue_depth, uint, NULL); NULLB_DEVICE_ATTR(index, uint, NULL); @@ -550,6 +555,7 @@ static struct configfs_attribute *nullb_device_attrs[] = { &nullb_device_attr_queue_mode, &nullb_device_attr_blocksize, &nullb_device_attr_max_sectors, + &nullb_device_attr_max_segment_size, &nullb_device_attr_irqmode, &nullb_device_attr_hw_queue_depth, &nullb_device_attr_index, @@ -630,7 +636,8 @@ static ssize_t memb_group_features_show(struct config_item *item, char *page) return snprintf(page, PAGE_SIZE, "badblocks,blocking,blocksize,cache_size," "completion_nsec,discard,home_node,hw_queue_depth," - "irqmode,max_sectors,mbps,memory_backed,no_sched," + "irqmode,max_sectors,max_segment_size,mbps," + "memory_backed,no_sched," "poll_queues,power,queue_mode,shared_tag_bitmap,size," "submit_queues,use_per_node_hctx,virt_boundary,zoned," "zone_capacity,zone_max_active,zone_max_open," @@ -693,6 +700,7 @@ static struct nullb_device *null_alloc_dev(void) dev->queue_mode = g_queue_mode; dev->blocksize = g_bs; dev->max_sectors = g_max_sectors; + dev->max_segment_size = g_max_segment_size; dev->irqmode = g_irqmode; dev->hw_queue_depth = g_hw_queue_depth; dev->blocking = g_blocking; @@ -1234,6 +1242,8 @@ static int null_transfer(struct nullb *nullb, struct page *page, unsigned int valid_len = len; int err = 0; + WARN_ONCE(len > dev->max_segment_size, "%u > %u\n", len, + dev->max_segment_size); if (!is_write) { if (dev->zoned) valid_len = null_zone_valid_read_len(nullb, @@ -1269,7 +1279,8 @@ static int null_handle_rq(struct nullb_cmd *cmd) spin_lock_irq(&nullb->lock); rq_for_each_segment(bvec, rq, iter) { - len = bvec.bv_len; + len = min(bvec.bv_len, nullb->dev->max_segment_size); + bvec.bv_len = len; err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset, op_is_write(req_op(rq)), sector, rq->cmd_flags & REQ_FUA); @@ -1296,7 +1307,8 @@ static int null_handle_bio(struct nullb_cmd *cmd) spin_lock_irq(&nullb->lock); bio_for_each_segment(bvec, bio, iter) { - len = bvec.bv_len; + len = min(bvec.bv_len, nullb->dev->max_segment_size); + bvec.bv_len = len; err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset, op_is_write(bio_op(bio)), sector, bio->bi_opf & REQ_FUA); @@ -2108,6 +2120,8 @@ static int null_add_dev(struct nullb_device *dev) nullb->q->queuedata = nullb; blk_queue_flag_set(QUEUE_FLAG_NONROT, nullb->q); blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, nullb->q); + if (dev->max_segment_size < PAGE_SIZE) + blk_queue_flag_set(QUEUE_FLAG_SUB_PAGE_SEGMENTS, nullb->q); mutex_lock(&lock); rv = ida_simple_get(&nullb_indexes, 0, 0, GFP_KERNEL); @@ -2125,6 +2139,7 @@ static int null_add_dev(struct nullb_device *dev) dev->max_sectors = queue_max_hw_sectors(nullb->q); dev->max_sectors = min(dev->max_sectors, BLK_DEF_MAX_SECTORS); blk_queue_max_hw_sectors(nullb->q, dev->max_sectors); + blk_queue_max_segment_size(nullb->q, dev->max_segment_size); if (dev->virt_boundary) blk_queue_virt_boundary(nullb->q, PAGE_SIZE - 1); diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h index eb5972c50be8..8cb73fe05fa3 100644 --- a/drivers/block/null_blk/null_blk.h +++ b/drivers/block/null_blk/null_blk.h @@ -102,6 +102,7 @@ struct nullb_device { unsigned int queue_mode; /* block interface */ unsigned int blocksize; /* block size */ unsigned int max_sectors; /* Max sectors per command */ + unsigned int max_segment_size; /* Max size of a single DMA segment. */ unsigned int irqmode; /* IRQ completion handler */ unsigned int hw_queue_depth; /* queue depth */ unsigned int index; /* index of the disk, only valid with a disk */