From patchwork Tue Jan 10 22:27:11 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejun Heo X-Patchwork-Id: 13095721 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 9AFDDC54EBC for ; Tue, 10 Jan 2023 22:27:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231727AbjAJW10 (ORCPT ); Tue, 10 Jan 2023 17:27:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43566 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234290AbjAJW1Z (ORCPT ); Tue, 10 Jan 2023 17:27:25 -0500 Received: from mail-pf1-x42e.google.com (mail-pf1-x42e.google.com [IPv6:2607:f8b0:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 013861001; Tue, 10 Jan 2023 14:27:24 -0800 (PST) Received: by mail-pf1-x42e.google.com with SMTP id s3so7474687pfd.12; Tue, 10 Jan 2023 14:27:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:sender:from:to:cc:subject:date :message-id:reply-to; bh=V71fAY4MFk3dJ0CASh+6M8Ag40kWVpFvHImvXgxVZzg=; b=Ucj4vMeUNfuTtkkX87ovhBXhpOPRwDUQWOgfIaOY/xOiPMEJ+KwmJiIpKuHd2e5zFq kLyjxE737kxjzxCoocDbVscbOL0p66kBMWGnOIRwcqwZugqO2hHtBuqyIcuqWXEGERxp mwHVa7JFN1QRNDtG22EU+qFIXbeLyTIv8j36HkMQCso3g1ejuFUvgPa3iG5nheoIhAoq fanXotRVjjmBhQDiZKJ3Wec+/vke6TFtFWhv39ulpzepxGWbwvcvnT932FZu/gJnnGAN 1ll6LrAU2HQSeP+5uQT7GSIcoQoXMtKn9yqpgoi8IeFwx7vj/VQYT9L+8KYK1y7Svv3s CmtQ== 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:sender:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=V71fAY4MFk3dJ0CASh+6M8Ag40kWVpFvHImvXgxVZzg=; b=odPeVRj5suaz6QZeMr6MIuqlOijS/9s7jQ5nZ7N4M3sK5RexLCFr4BN7dXXQN9mXpp Hi1ADQM0RYiaa27BApD8ryNuc8nLoLYgbZ+4Ss41IAHcLc1V77PGpLb/IZct94+s5Gnj dexW0TMkqfk42QI9V5iK5RmjgS1p8L2tKI7k1A8rvh2c7dDBy5yEJE532IQooYNMVx1a +CjTij39wNHARlZUj1r/wUAR/9Uyxp9W8uLn7g1vkblMurZW3iNH09N+ub0DVrE+TxYj jFBCCNj9tmRWEOkZCDWH/IKaGCIBRoIL6bueIU/du7MgBbR15LHMJ6F/fz12Z/uV6Roe Xw8w== X-Gm-Message-State: AFqh2kpRjYPJR7Bi+OPc7TfdpaTw0gF6zd0hRm8wZWRHdzeANvHOjGhm nKZylWvYAT7X3bdJMfbNS9k= X-Google-Smtp-Source: AMrXdXv16X7Z5h/Vu/hJ3FoBiww67aXvypfcDbXctYCfyvWKDqkVz7yzOQ0qQZEEOlOdsseGyTd96w== X-Received: by 2002:a05:6a00:f92:b0:582:a224:e740 with SMTP id ct18-20020a056a000f9200b00582a224e740mr30097176pfb.27.1673389643263; Tue, 10 Jan 2023 14:27:23 -0800 (PST) Received: from localhost (2603-800c-1a02-1bae-a7fa-157f-969a-4cde.res6.spectrum.com. [2603:800c:1a02:1bae:a7fa:157f:969a:4cde]) by smtp.gmail.com with ESMTPSA id 2-20020a620502000000b00580cf1be16csm8555886pff.137.2023.01.10.14.27.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Jan 2023 14:27:22 -0800 (PST) Sender: Tejun Heo From: Tejun Heo To: axboe@kernel.dk, josef@toxicpanda.com, hch@lst.de Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 1/4] blkcg: Drop unnecessary RCU read [un]locks from blkg_conf_prep/finish() Date: Tue, 10 Jan 2023 12:27:11 -1000 Message-Id: <20230110222714.552241-2-tj@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230110222714.552241-1-tj@kernel.org> References: <20230110222714.552241-1-tj@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Now that all RCU flavors have been combined either holding a spin lock, disabling irq or disabling preemption implies RCU read lock, so there's no need to use rcu_read_[un]lock() explicitly while holding queue_lock. This shouldn't cause any behavior changes. v2: Description updated. Leave __acquires/release on queue_lock alone. Signed-off-by: Tejun Heo --- block/blk-cgroup.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index ce6a2b7d3dfb..7d338bc84387 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -672,12 +672,12 @@ struct block_device *blkcg_conf_open_bdev(char **inputp) * * Parse per-blkg config update from @input and initialize @ctx with the * result. @ctx->blkg points to the blkg to be updated and @ctx->body the - * part of @input following MAJ:MIN. This function returns with RCU read - * lock and queue lock held and must be paired with blkg_conf_finish(). + * part of @input following MAJ:MIN. This function returns with queue lock + * held and must be paired with blkg_conf_finish(). */ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, char *input, struct blkg_conf_ctx *ctx) - __acquires(rcu) __acquires(&bdev->bd_queue->queue_lock) + __acquires(&bdev->bd_queue->queue_lock) { struct block_device *bdev; struct gendisk *disk; @@ -699,7 +699,6 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, if (ret) goto fail; - rcu_read_lock(); spin_lock_irq(&q->queue_lock); if (!blkcg_policy_enabled(q, pol)) { @@ -728,7 +727,6 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, /* Drop locks to do new blkg allocation with GFP_KERNEL. */ spin_unlock_irq(&q->queue_lock); - rcu_read_unlock(); new_blkg = blkg_alloc(pos, disk, GFP_KERNEL); if (unlikely(!new_blkg)) { @@ -742,7 +740,6 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, goto fail_exit_queue; } - rcu_read_lock(); spin_lock_irq(&q->queue_lock); if (!blkcg_policy_enabled(q, pol)) { @@ -778,7 +775,6 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, radix_tree_preload_end(); fail_unlock: spin_unlock_irq(&q->queue_lock); - rcu_read_unlock(); fail_exit_queue: blk_queue_exit(q); fail: @@ -805,10 +801,9 @@ EXPORT_SYMBOL_GPL(blkg_conf_prep); * with blkg_conf_prep(). */ void blkg_conf_finish(struct blkg_conf_ctx *ctx) - __releases(&ctx->bdev->bd_queue->queue_lock) __releases(rcu) + __releases(&ctx->bdev->bd_queue->queue_lock) { spin_unlock_irq(&bdev_get_queue(ctx->bdev)->queue_lock); - rcu_read_unlock(); blkdev_put_no_open(ctx->bdev); } EXPORT_SYMBOL_GPL(blkg_conf_finish); From patchwork Tue Jan 10 22:27:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejun Heo X-Patchwork-Id: 13095722 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 CDA39C46467 for ; Tue, 10 Jan 2023 22:27:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234574AbjAJW1k (ORCPT ); Tue, 10 Jan 2023 17:27:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234505AbjAJW11 (ORCPT ); Tue, 10 Jan 2023 17:27:27 -0500 Received: from mail-pf1-x42a.google.com (mail-pf1-x42a.google.com [IPv6:2607:f8b0:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CFD1E63DF; Tue, 10 Jan 2023 14:27:25 -0800 (PST) Received: by mail-pf1-x42a.google.com with SMTP id a30so9995864pfr.6; Tue, 10 Jan 2023 14:27:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:sender:from:to:cc:subject:date :message-id:reply-to; bh=XryDKqeNZ1rCo4apOKrM//W5RPcA2SaI+F2YSj7hZoY=; b=dTv4AYsee92CDRNniVy06fFJSBoZyHIXT+7fSuxUl6Ry8V5wwaBpvm7Qr9TIjGHb4T XwHBGfW+rI7Qm4skC3Au5uPO9Pk8tqd6LVMGFOyekqye8FIMAigI/2kTgvUGYf8qWpge 5O4kXcTjY5xq7dZZ6jOqhRIGXcNxsaRzqbhGrYPgNGJdrjuK8o7fR/LazOleKzgLMzY4 gtN6ATOFF9HH9pAdB6INScXZRYQlEdqZSdIUme6gqqsnU8Mgvp+qNPqdtGIl2y2y8Qoo /IyUOmR4xytr80es2L3E6LRJXzKQIqqDHxat47jdMorX76PZph+8ji87gwwhTKxBNGXF kerg== 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:sender:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=XryDKqeNZ1rCo4apOKrM//W5RPcA2SaI+F2YSj7hZoY=; b=FHvYrQhNB6ayWW85G2cpjNTJEJiHHJbTmDDeQ01dQDmRJ2ZOB0QppCGJrFEb4l6O2E P4k9rk/yQ+BHOEkv5dHTYCPoiNVSDrMUwyRT3ofh+G4/jDpxoi7QbIDmoVlouF9bwOXh jkWqYNShJiMgep4NAtV4pvUpbqe3sWVMS6CkQPW0+pVLNCzKxEmCMsWn+JMpABzdFc2d 8RhxU75cUUNMhSK7OVAWwgmVQxNY1Rh8FqUCuGIYQjak6/uDuy29KaS447kkQDTchruQ N8KnqT4aC5IcXtanhOIOo4ft7Lnf7DU+5smRlfxnYEyBAesojjzfD+p8r76L1NrXufUv CJlA== X-Gm-Message-State: AFqh2kqJYoJqXBAqFBkcdvxpRsJ0IP2Fi6Qehols+xbWicWgqvjHBi8a GuXz20jKzyD4Aon501PnHCE= X-Google-Smtp-Source: AMrXdXsEJwLj+yEMvs88EE+HK1iZ7F4fxJIqQgi24ebKlODo/YxL74YtpH+9FAiWsqWdcaGw4z4cZg== X-Received: by 2002:aa7:91d4:0:b0:588:32ce:eea4 with SMTP id z20-20020aa791d4000000b0058832ceeea4mr8180340pfa.15.1673389645136; Tue, 10 Jan 2023 14:27:25 -0800 (PST) Received: from localhost (2603-800c-1a02-1bae-a7fa-157f-969a-4cde.res6.spectrum.com. [2603:800c:1a02:1bae:a7fa:157f:969a:4cde]) by smtp.gmail.com with ESMTPSA id e18-20020aa79812000000b0058119caa82csm8526898pfl.205.2023.01.10.14.27.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Jan 2023 14:27:24 -0800 (PST) Sender: Tejun Heo From: Tejun Heo To: axboe@kernel.dk, josef@toxicpanda.com, hch@lst.de Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo , Yu Kuai Subject: [PATCH 2/4] blkcg: Restructure blkg_conf_prep() and friends Date: Tue, 10 Jan 2023 12:27:12 -1000 Message-Id: <20230110222714.552241-3-tj@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230110222714.552241-1-tj@kernel.org> References: <20230110222714.552241-1-tj@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org We want to support lazy init of rq-qos policies so that iolatency is enabled lazily on configuration instead of gendisk initialization. The way blkg config helpers are structured now is a bit awkward for that. Let's restructure: * blkcg_conf_open_bdev() is renamed to blkg_conf_open_bdev(). The blkcg_ prefix was used because the bdev opening step is blkg-independent. However, the distinction is too subtle and confuses more than helps. Let's switch to blkg prefix so that it's consistent with the type and other helper names. * struct blkg_conf_ctx now remembers the original input string and is always initialized by the new blkg_conf_init(). * blkg_conf_open_bdev() is updated to take a pointer to blkg_conf_ctx like blkg_conf_prep() and can be called multiple times safely. Instead of modifying the double pointer to input string directly, blkg_conf_open_bdev() now sets blkg_conf_ctx->body. * blkg_conf_finish() is renamed to blkg_conf_exit() for symmetry and now must be called on all blkg_conf_ctx's which were initialized with blkg_conf_init(). Combined, this allows the users to either open the bdev first or do it altogether with blkg_conf_prep() which will help implementing lazy init of rq-qos policies. blkg_conf_init/exit() will also be used implement synchronization against device removal. This is necessary because iolat / iocost are configured through cgroupfs instead of one of the files under /sys/block/DEVICE. As cgroupfs operations aren't synchronized with block layer, the lazy init and other configuration operations may race against device removal. This patch makes blkg_conf_init/exit() used consistently for all cgroup-orginating configurations making them a good place to implement explicit synchronization. Users are updated accordingly. No behavior change is intended by this patch. v2: bfq wasn't updated in v1 causing a build error. Fixed. v3: Update the description to include future use of blkg_conf_init/exit() as synchronization points. Signed-off-by: Tejun Heo Cc: Josef Bacik Cc: Christoph Hellwig Cc: Yu Kuai --- block/bfq-cgroup.c | 8 ++-- block/blk-cgroup.c | 105 +++++++++++++++++++++++++++--------------- block/blk-cgroup.h | 10 ++-- block/blk-iocost.c | 58 +++++++++++++---------- block/blk-iolatency.c | 8 ++-- block/blk-throttle.c | 16 ++++--- 6 files changed, 127 insertions(+), 78 deletions(-) diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index a6e8da5f5cfd..97925793aee4 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -1115,9 +1115,11 @@ static ssize_t bfq_io_set_device_weight(struct kernfs_open_file *of, struct bfq_group *bfqg; u64 v; - ret = blkg_conf_prep(blkcg, &blkcg_policy_bfq, buf, &ctx); + blkg_conf_init(&ctx, buf); + + ret = blkg_conf_prep(blkcg, &blkcg_policy_bfq, &ctx); if (ret) - return ret; + goto out; if (sscanf(ctx.body, "%llu", &v) == 1) { /* require "default" on dfl */ @@ -1139,7 +1141,7 @@ static ssize_t bfq_io_set_device_weight(struct kernfs_open_file *of, ret = 0; } out: - blkg_conf_finish(&ctx); + blkg_conf_exit(&ctx); return ret ?: nbytes; } diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 7d338bc84387..18fbdea1f756 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -626,69 +626,93 @@ u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) EXPORT_SYMBOL_GPL(__blkg_prfill_u64); /** - * blkcg_conf_open_bdev - parse and open bdev for per-blkg config update - * @inputp: input string pointer + * blkg_conf_init - initialize a blkg_conf_ctx + * @ctx: blkg_conf_ctx to initialize + * @input: input string * - * Parse the device node prefix part, MAJ:MIN, of per-blkg config update - * from @input and get and return the matching bdev. *@inputp is - * updated to point past the device node prefix. Returns an ERR_PTR() - * value on error. + * Initialize @ctx which can be used to parse blkg config input string @input. + * Once initialized, @ctx can be used with blkg_conf_open_bdev() and + * blkg_conf_prep(), and must be cleaned up with blkg_conf_exit(). + */ +void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input) +{ + *ctx = (struct blkg_conf_ctx){ .input = input }; +} +EXPORT_SYMBOL_GPL(blkg_conf_init); + +/** + * blkg_conf_open_bdev - parse and open bdev for per-blkg config update + * @ctx: blkg_conf_ctx initialized with blkg_conf_init() * - * Use this function iff blkg_conf_prep() can't be used for some reason. + * Parse the device node prefix part, MAJ:MIN, of per-blkg config update from + * @ctx->input and get and store the matching bdev in @ctx->bdev. @ctx->body is + * set to point past the device node prefix. + * + * This function may be called multiple times on @ctx and the extra calls become + * NOOPs. blkg_conf_prep() implicitly calls this function. Use this function + * explicitly if bdev access is needed without resolving the blkcg / policy part + * of @ctx->input. Returns -errno on error. */ -struct block_device *blkcg_conf_open_bdev(char **inputp) +int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx) { - char *input = *inputp; + char *input = ctx->input; unsigned int major, minor; struct block_device *bdev; int key_len; + if (ctx->bdev) + return 0; + if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2) - return ERR_PTR(-EINVAL); + return -EINVAL; input += key_len; if (!isspace(*input)) - return ERR_PTR(-EINVAL); + return -EINVAL; input = skip_spaces(input); bdev = blkdev_get_no_open(MKDEV(major, minor)); if (!bdev) - return ERR_PTR(-ENODEV); + return -ENODEV; if (bdev_is_partition(bdev)) { blkdev_put_no_open(bdev); - return ERR_PTR(-ENODEV); + return -ENODEV; } - *inputp = input; - return bdev; + ctx->body = input; + ctx->bdev = bdev; + return 0; } /** * blkg_conf_prep - parse and prepare for per-blkg config update * @blkcg: target block cgroup * @pol: target policy - * @input: input string - * @ctx: blkg_conf_ctx to be filled + * @ctx: blkg_conf_ctx initialized with blkg_conf_init() + * + * Parse per-blkg config update from @ctx->input and initialize @ctx + * accordingly. On success, @ctx->body points to the part of @ctx->input + * following MAJ:MIN, @ctx->bdev points to the target block device and + * @ctx->blkg to the blkg being configured. * - * Parse per-blkg config update from @input and initialize @ctx with the - * result. @ctx->blkg points to the blkg to be updated and @ctx->body the - * part of @input following MAJ:MIN. This function returns with queue lock - * held and must be paired with blkg_conf_finish(). + * blkg_conf_open_bdev() may be called on @ctx beforehand. On success, this + * function returns with queue lock held and must be followed by + * blkg_conf_exit(). */ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, - char *input, struct blkg_conf_ctx *ctx) + struct blkg_conf_ctx *ctx) __acquires(&bdev->bd_queue->queue_lock) { - struct block_device *bdev; struct gendisk *disk; struct request_queue *q; struct blkcg_gq *blkg; int ret; - bdev = blkcg_conf_open_bdev(&input); - if (IS_ERR(bdev)) - return PTR_ERR(bdev); - disk = bdev->bd_disk; + ret = blkg_conf_open_bdev(ctx); + if (ret) + return ret; + + disk = ctx->bdev->bd_disk; q = disk->queue; /* @@ -766,9 +790,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, } success: blk_queue_exit(q); - ctx->bdev = bdev; ctx->blkg = blkg; - ctx->body = input; return 0; fail_preloaded: @@ -778,7 +800,6 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, fail_exit_queue: blk_queue_exit(q); fail: - blkdev_put_no_open(bdev); /* * If queue was bypassing, we should retry. Do so after a * short msleep(). It isn't strictly necessary but queue @@ -794,19 +815,27 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, EXPORT_SYMBOL_GPL(blkg_conf_prep); /** - * blkg_conf_finish - finish up per-blkg config update - * @ctx: blkg_conf_ctx initialized by blkg_conf_prep() + * blkg_conf_exit - clean up per-blkg config update + * @ctx: blkg_conf_ctx initialized with blkg_conf_init() * - * Finish up after per-blkg config update. This function must be paired - * with blkg_conf_prep(). + * Clean up after per-blkg config update. This function must be called on all + * blkg_conf_ctx's initialized with blkg_conf_init(). */ -void blkg_conf_finish(struct blkg_conf_ctx *ctx) +void blkg_conf_exit(struct blkg_conf_ctx *ctx) __releases(&ctx->bdev->bd_queue->queue_lock) { - spin_unlock_irq(&bdev_get_queue(ctx->bdev)->queue_lock); - blkdev_put_no_open(ctx->bdev); + if (ctx->blkg) { + spin_unlock_irq(&bdev_get_queue(ctx->bdev)->queue_lock); + ctx->blkg = NULL; + } + + if (ctx->bdev) { + blkdev_put_no_open(ctx->bdev); + ctx->body = NULL; + ctx->bdev = NULL; + } } -EXPORT_SYMBOL_GPL(blkg_conf_finish); +EXPORT_SYMBOL_GPL(blkg_conf_exit); static void blkg_iostat_set(struct blkg_iostat *dst, struct blkg_iostat *src) { diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 1e94e404eaa8..fe09e8b4c2a8 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -208,15 +208,17 @@ void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v); struct blkg_conf_ctx { + char *input; + char *body; struct block_device *bdev; struct blkcg_gq *blkg; - char *body; }; -struct block_device *blkcg_conf_open_bdev(char **inputp); +void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input); +int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx); int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, - char *input, struct blkg_conf_ctx *ctx); -void blkg_conf_finish(struct blkg_conf_ctx *ctx); + struct blkg_conf_ctx *ctx); +void blkg_conf_exit(struct blkg_conf_ctx *ctx); /** * bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg diff --git a/block/blk-iocost.c b/block/blk-iocost.c index 6955605629e4..22a3639a7a05 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -3091,9 +3091,11 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf, return nbytes; } - ret = blkg_conf_prep(blkcg, &blkcg_policy_iocost, buf, &ctx); + blkg_conf_init(&ctx, buf); + + ret = blkg_conf_prep(blkcg, &blkcg_policy_iocost, &ctx); if (ret) - return ret; + goto err; iocg = blkg_to_iocg(ctx.blkg); @@ -3112,12 +3114,14 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf, weight_updated(iocg, &now); spin_unlock(&iocg->ioc->lock); - blkg_conf_finish(&ctx); + blkg_conf_exit(&ctx); return nbytes; einval: - blkg_conf_finish(&ctx); - return -EINVAL; + ret = -EINVAL; +err: + blkg_conf_exit(&ctx); + return ret; } static u64 ioc_qos_prfill(struct seq_file *sf, struct blkg_policy_data *pd, @@ -3172,19 +3176,22 @@ static const match_table_t qos_tokens = { static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input, size_t nbytes, loff_t off) { - struct block_device *bdev; + struct blkg_conf_ctx ctx; struct gendisk *disk; struct ioc *ioc; u32 qos[NR_QOS_PARAMS]; bool enable, user; - char *p; + char *body, *p; int ret; - bdev = blkcg_conf_open_bdev(&input); - if (IS_ERR(bdev)) - return PTR_ERR(bdev); + blkg_conf_init(&ctx, input); - disk = bdev->bd_disk; + ret = blkg_conf_open_bdev(&ctx); + if (ret) + goto err; + + body = ctx.body; + disk = ctx.bdev->bd_disk; ioc = q_to_ioc(disk->queue); if (!ioc) { ret = blk_iocost_init(disk); @@ -3201,7 +3208,7 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input, enable = ioc->enabled; user = ioc->user_qos_params; - while ((p = strsep(&input, " \t\n"))) { + while ((p = strsep(&body, " \t\n"))) { substring_t args[MAX_OPT_ARGS]; char buf[32]; int tok; @@ -3290,7 +3297,7 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input, blk_mq_unquiesce_queue(disk->queue); blk_mq_unfreeze_queue(disk->queue); - blkdev_put_no_open(bdev); + blkg_conf_exit(&ctx); return nbytes; einval: spin_unlock_irq(&ioc->lock); @@ -3300,7 +3307,7 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input, ret = -EINVAL; err: - blkdev_put_no_open(bdev); + blkg_conf_exit(&ctx); return ret; } @@ -3351,22 +3358,25 @@ static const match_table_t i_lcoef_tokens = { static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input, size_t nbytes, loff_t off) { - struct block_device *bdev; + struct blkg_conf_ctx ctx; struct request_queue *q; struct ioc *ioc; u64 u[NR_I_LCOEFS]; bool user; - char *p; + char *body, *p; int ret; - bdev = blkcg_conf_open_bdev(&input); - if (IS_ERR(bdev)) - return PTR_ERR(bdev); + blkg_conf_init(&ctx, input); + + ret = blkg_conf_open_bdev(&ctx); + if (ret) + goto err; - q = bdev_get_queue(bdev); + body = ctx.body; + q = bdev_get_queue(ctx.bdev); ioc = q_to_ioc(q); if (!ioc) { - ret = blk_iocost_init(bdev->bd_disk); + ret = blk_iocost_init(ctx.bdev->bd_disk); if (ret) goto err; ioc = q_to_ioc(q); @@ -3379,7 +3389,7 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input, memcpy(u, ioc->params.i_lcoefs, sizeof(u)); user = ioc->user_cost_model; - while ((p = strsep(&input, " \t\n"))) { + while ((p = strsep(&body, " \t\n"))) { substring_t args[MAX_OPT_ARGS]; char buf[32]; int tok; @@ -3426,7 +3436,7 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input, blk_mq_unquiesce_queue(q); blk_mq_unfreeze_queue(q); - blkdev_put_no_open(bdev); + blkg_conf_exit(&ctx); return nbytes; einval: @@ -3437,7 +3447,7 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input, ret = -EINVAL; err: - blkdev_put_no_open(bdev); + blkg_conf_exit(&ctx); return ret; } diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index ecdc10741836..3b3667f397a9 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -842,9 +842,11 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf, u64 oldval; int ret; - ret = blkg_conf_prep(blkcg, &blkcg_policy_iolatency, buf, &ctx); + blkg_conf_init(&ctx, buf); + + ret = blkg_conf_prep(blkcg, &blkcg_policy_iolatency, &ctx); if (ret) - return ret; + goto out; iolat = blkg_to_lat(ctx.blkg); p = ctx.body; @@ -880,7 +882,7 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf, iolatency_clear_scaling(blkg); ret = 0; out: - blkg_conf_finish(&ctx); + blkg_conf_exit(&ctx); return ret ?: nbytes; } diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 6fb5a2f9e1ee..75841d1d9bf4 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1369,9 +1369,11 @@ static ssize_t tg_set_conf(struct kernfs_open_file *of, int ret; u64 v; - ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); + blkg_conf_init(&ctx, buf); + + ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, &ctx); if (ret) - return ret; + goto out_finish; ret = -EINVAL; if (sscanf(ctx.body, "%llu", &v) != 1) @@ -1390,7 +1392,7 @@ static ssize_t tg_set_conf(struct kernfs_open_file *of, tg_conf_updated(tg, false); ret = 0; out_finish: - blkg_conf_finish(&ctx); + blkg_conf_exit(&ctx); return ret ?: nbytes; } @@ -1562,9 +1564,11 @@ static ssize_t tg_set_limit(struct kernfs_open_file *of, int ret; int index = of_cft(of)->private; - ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); + blkg_conf_init(&ctx, buf); + + ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, &ctx); if (ret) - return ret; + goto out_finish; tg = blkg_to_tg(ctx.blkg); tg_update_carryover(tg); @@ -1663,7 +1667,7 @@ static ssize_t tg_set_limit(struct kernfs_open_file *of, tg->td->limit_valid[LIMIT_LOW]); ret = 0; out_finish: - blkg_conf_finish(&ctx); + blkg_conf_exit(&ctx); 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[2603:800c:1a02:1bae:a7fa:157f:969a:4cde]) by smtp.gmail.com with ESMTPSA id e11-20020a056a0000cb00b00582e4fda343sm7015762pfj.200.2023.01.10.14.27.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Jan 2023 14:27:26 -0800 (PST) Sender: Tejun Heo From: Tejun Heo To: axboe@kernel.dk, josef@toxicpanda.com, hch@lst.de Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 3/4] blk-iolatency: s/blkcg_rq_qos/iolat_rq_qos/ Date: Tue, 10 Jan 2023 12:27:13 -1000 Message-Id: <20230110222714.552241-4-tj@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230110222714.552241-1-tj@kernel.org> References: <20230110222714.552241-1-tj@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org The name was too generic given that there are multiple blkcg rq-qos policies. Signed-off-by: Tejun Heo Reviewed-by: Christoph Hellwig Cc: Josef Bacik --- block/blk-iolatency.c | 2 +- block/blk-rq-qos.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index 3b3667f397a9..3601345808d2 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -976,7 +976,7 @@ static void iolatency_pd_init(struct blkg_policy_data *pd) { struct iolatency_grp *iolat = pd_to_lat(pd); struct blkcg_gq *blkg = lat_to_blkg(iolat); - struct rq_qos *rqos = blkcg_rq_qos(blkg->q); + struct rq_qos *rqos = iolat_rq_qos(blkg->q); struct blk_iolatency *blkiolat = BLKIOLATENCY(rqos); u64 now = ktime_to_ns(ktime_get()); int cpu; diff --git a/block/blk-rq-qos.h b/block/blk-rq-qos.h index 1ef1f7d4bc3c..27f004fae66b 100644 --- a/block/blk-rq-qos.h +++ b/block/blk-rq-qos.h @@ -74,7 +74,7 @@ static inline struct rq_qos *wbt_rq_qos(struct request_queue *q) return rq_qos_id(q, RQ_QOS_WBT); } -static inline struct rq_qos *blkcg_rq_qos(struct request_queue *q) +static inline struct rq_qos *iolat_rq_qos(struct request_queue *q) { return rq_qos_id(q, RQ_QOS_LATENCY); } From patchwork Tue Jan 10 22:27:14 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejun Heo X-Patchwork-Id: 13095724 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 4EABAC54EBC for ; Tue, 10 Jan 2023 22:27:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231332AbjAJW1r (ORCPT ); Tue, 10 Jan 2023 17:27:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234797AbjAJW1j (ORCPT ); Tue, 10 Jan 2023 17:27:39 -0500 Received: from mail-pl1-x632.google.com (mail-pl1-x632.google.com [IPv6:2607:f8b0:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9044610F0; Tue, 10 Jan 2023 14:27:29 -0800 (PST) Received: by mail-pl1-x632.google.com with SMTP id 17so14786973pll.0; Tue, 10 Jan 2023 14:27:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:sender:from:to:cc:subject:date :message-id:reply-to; bh=As6nNAmXM4tdIzqTWu5Dx71F5R4c768lyUE/zpN/pFA=; b=kSqHHe1tiriRF7t2MDLU28ZAjUnWsk+aXHgU2P+dCTranSh9oubRYirI7n3bN1tdXS dx4Sm9EGx2OAqqKerRQPKwCGPyP5APrAh3l2UkMAEBzmfS0RSuy8Cco64YbkZirRN6tz nHz50rbnq1rG33kHpvhEU1oeAcYymFSD1uqRL4sNRb0bms347/hxbn/GvrMWa/cx4owX TjfkM3SxDcCCs++qLNYcD6hvkBvotdhbiM75CqulAiPtRkidueuC0OjLbaqhgFMEYzI0 9uBTSVjPb22Urb+mbBue/hkv7YmntKdLzrkpLQR+6DOhU8PAYJkLh3A4N0h0JhVJkgV+ Qchg== 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:sender:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=As6nNAmXM4tdIzqTWu5Dx71F5R4c768lyUE/zpN/pFA=; b=4HSmYbJMeecR2x4tBYKSbCLHVNkTp5iypLvEuXk1EW0cHuII4ObB1e5aHMzTmGjKtX o24bnePJWh4bV14Mss0C2nld5Z/On/VTpOJjcLCwQtjBcpBHYgRZlfOtMP57IvYo4rJ5 HiFDq83zl9xoUYuFvwOLflS+ha01l/CBury5toDrbhGjOs4lAA07q+5mbacFvmTEMz5+ FK46b3SfQzsYsBmSfARuGRB8Unug0vtR/65kvyKMLaDNIlaZ7AmmO/L3ZgaQDCcp1FYv vmgEYSrfX52l5kV9W03F05e0mk/mga/hSa5nyN+ysXUa7zSDKOUTUGhtJlcbKxO1XprM UXzQ== X-Gm-Message-State: AFqh2krrFNjO0uuaAhXFUuAiUaEk5xq0VLFQ/T8w7JFB+PfnW91JJHve uvyOFKhWPx54guMAPBtyJR8= X-Google-Smtp-Source: AMrXdXsYlPW0VH/0oKoavsb9npQ+pXKm/9qLaBGLhUpZw+iw6G3kwBYD89PTxAxMTAATn5obdFDAmw== X-Received: by 2002:a05:6a21:9986:b0:b6:1425:55df with SMTP id ve6-20020a056a21998600b000b6142555dfmr196751pzb.59.1673389648863; Tue, 10 Jan 2023 14:27:28 -0800 (PST) Received: from localhost (2603-800c-1a02-1bae-a7fa-157f-969a-4cde.res6.spectrum.com. [2603:800c:1a02:1bae:a7fa:157f:969a:4cde]) by smtp.gmail.com with ESMTPSA id d13-20020a170902f14d00b001873aa85e1fsm8516012plb.305.2023.01.10.14.27.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Jan 2023 14:27:28 -0800 (PST) Sender: Tejun Heo From: Tejun Heo To: axboe@kernel.dk, josef@toxicpanda.com, hch@lst.de Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 4/4] blk-iolatency: Make initialization lazy Date: Tue, 10 Jan 2023 12:27:14 -1000 Message-Id: <20230110222714.552241-5-tj@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230110222714.552241-1-tj@kernel.org> References: <20230110222714.552241-1-tj@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Other rq_qos policies such as wbt and iocost are lazy-initialized when they are configured for the first time for the device but iolatency is initialized unconditionally from blkcg_init_disk() during gendisk init. Lazy init is beneficial because rq_qos policies add runtime overhead when initialized as every IO has to walk all registered rq_qos callbacks. This patch switches iolatency to lazy initialization too so that it only registered its rq_qos policy when it is first configured. Note that there is a known race condition between blkcg config file writes and del_gendisk() and this patch makes iolatency susceptible to it by exposing the init path to race against the deletion path. However, that problem already exists in iocost and is being worked on. Signed-off-by: Tejun Heo Reviewed-by: Christoph Hellwig Cc: Josef Bacik --- block/blk-cgroup.c | 8 -------- block/blk-iolatency.c | 29 ++++++++++++++++++++++++++++- block/blk.h | 6 ------ 3 files changed, 28 insertions(+), 15 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 18fbdea1f756..54e3ab68a9ac 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -33,7 +33,6 @@ #include "blk-cgroup.h" #include "blk-ioprio.h" #include "blk-throttle.h" -#include "blk-rq-qos.h" /* * blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation. @@ -1324,14 +1323,8 @@ int blkcg_init_disk(struct gendisk *disk) if (ret) goto err_ioprio_exit; - ret = blk_iolatency_init(disk); - if (ret) - goto err_throtl_exit; - return 0; -err_throtl_exit: - blk_throtl_exit(disk); err_ioprio_exit: blk_ioprio_exit(disk); err_destroy_all: @@ -1347,7 +1340,6 @@ int blkcg_init_disk(struct gendisk *disk) void blkcg_exit_disk(struct gendisk *disk) { blkg_destroy_all(disk); - rq_qos_exit(disk->queue); blk_throtl_exit(disk); } diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index 3601345808d2..3484393dbc4a 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -755,7 +755,7 @@ static void blkiolatency_enable_work_fn(struct work_struct *work) } } -int blk_iolatency_init(struct gendisk *disk) +static int blk_iolatency_init(struct gendisk *disk) { struct request_queue *q = disk->queue; struct blk_iolatency *blkiolat; @@ -830,6 +830,29 @@ static void iolatency_clear_scaling(struct blkcg_gq *blkg) } } +static int blk_iolatency_try_init(struct blkg_conf_ctx *ctx) +{ + static DEFINE_MUTEX(init_mutex); + int ret; + + ret = blkg_conf_open_bdev(ctx); + if (ret) + return ret; + + /* + * blk_iolatency_init() may fail after rq_qos_add() succeeds which can + * confuse iolat_rq_qos() test. Make the test and init atomic. + */ + mutex_lock(&init_mutex); + + if (!iolat_rq_qos(ctx->bdev->bd_queue)) + ret = blk_iolatency_init(ctx->bdev->bd_disk); + + mutex_unlock(&init_mutex); + + return ret; +} + static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { @@ -844,6 +867,10 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf, blkg_conf_init(&ctx, buf); + ret = blk_iolatency_try_init(&ctx); + if (ret) + goto out; + ret = blkg_conf_prep(blkcg, &blkcg_policy_iolatency, &ctx); if (ret) goto out; diff --git a/block/blk.h b/block/blk.h index 4c3b3325219a..78f1706cddca 100644 --- a/block/blk.h +++ b/block/blk.h @@ -392,12 +392,6 @@ static inline struct bio *blk_queue_bounce(struct bio *bio, return bio; } -#ifdef CONFIG_BLK_CGROUP_IOLATENCY -int blk_iolatency_init(struct gendisk *disk); -#else -static inline int blk_iolatency_init(struct gendisk *disk) { return 0; }; -#endif - #ifdef CONFIG_BLK_DEV_ZONED void disk_free_zone_bitmaps(struct gendisk *disk); void disk_clear_zone_settings(struct gendisk *disk);