From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EB70722126A for ; Thu, 24 Apr 2025 15:22:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745508174; cv=none; b=kKs6DMUZSF34K845qnrq8/S0njZKJ9jLLsH21nrVPhhtwQXSuqxxgSRgsQUx9hVxPUUyggqbxunbKomBODRVq1KRFwOifcSvpUNlFHKrgmcBA/gFMlVKYQmtBAZzuehS/vEtU2FsSZsLcYovH/Z3f9ySYF71fz+mfhIwuI5jMmU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745508174; c=relaxed/simple; bh=CzM2Q4HC3aokSojsCEHQINZ7nXsNtibE1XLA1brrZ5c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nOhjc2eAZ9SHEvjm6nOSLXl3cI7Ksow3qJhRVMFKLXC7ehXt3J6jForjhGj/fsxhKXqzI4VBm86bf9xMhbYUNbvuk25i9TPeEhdfNcR2ZYU4SD8w3HrhToHVFSSkJDZI5vdlF9rjiWo98GJe6Yx+DT58YjKlu+WLJj8Uk0e3H58= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=AZh+iwlq; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="AZh+iwlq" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1745508171; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0a7RwfgHfzVEf2MwIwYHonikB6Gcy3NfQQUEHYI7odk=; b=AZh+iwlqwq8FU8a41DL93tZ15QFiDOiMO+BtvhW0kC4ZFdFekJMsLnv28uBkhYN5m4bDc6 PtAEIo7M5VYjRrM/UqISVOEf89NM1HAYltjo6wzIXEo18Iw097nFi4u1yR99K+w3McPdUp NIAjmdvQVd3walNBRrOliuH2CHunFH8= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-418-oUkM-gmuOMOR9hp6GV4Dzg-1; Thu, 24 Apr 2025 11:22:48 -0400 X-MC-Unique: oUkM-gmuOMOR9hp6GV4Dzg-1 X-Mimecast-MFC-AGG-ID: oUkM-gmuOMOR9hp6GV4Dzg_1745508167 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id EBB051800373; Thu, 24 Apr 2025 15:22:46 +0000 (UTC) Received: from localhost (unknown [10.72.116.90]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id CEDD0180045C; Thu, 24 Apr 2025 15:22:45 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org Cc: Nilay Shroff , Shinichiro Kawasaki , =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= , Christoph Hellwig , Ming Lei Subject: [PATCH V3 13/20] block: unifying elevator change Date: Thu, 24 Apr 2025 23:21:36 +0800 Message-ID: <20250424152148.1066220-14-ming.lei@redhat.com> In-Reply-To: <20250424152148.1066220-1-ming.lei@redhat.com> References: <20250424152148.1066220-1-ming.lei@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 elevator change is one well-define behavior: - tear down current elevator if it exists - setup new elevator It is supposed to cover any case for changing elevator by single internal API, typically the following cases: - setup default elevator in add_disk() - switch to none in del_disk() - reset elevator in blk_mq_update_nr_hw_queues() - switch elevator in sysfs `store` elevator attribute This patch uses elevator_change() to cover all above cases: - every elevator switch is serialized with each other: add_disk/del_disk/ store elevator is serialized already, blk_mq_update_nr_hw_queues() uses srcu for syncing with the other three cases - for both add_disk()/del_disk(), queue freeze works at atomic mode or has been froze, so the freeze in elevator_change() won't add extra delay - `struct elev_change_ctx` instance holds any info for changing elevator Signed-off-by: Ming Lei --- block/blk-sysfs.c | 18 +++----- block/blk.h | 5 +- block/elevator.c | 114 +++++++++++++++++++++++++--------------------- block/genhd.c | 28 ++---------- 4 files changed, 75 insertions(+), 90 deletions(-) diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 1f9b45b0b9ee..9aa05666f32a 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -869,14 +869,8 @@ int blk_register_queue(struct gendisk *disk) if (ret) goto out_unregister_ia_ranges; + elevator_set_default(q); mutex_lock(&q->elevator_lock); - if (q->elevator) { - ret = elv_register_queue(q, false); - if (ret) { - mutex_unlock(&q->elevator_lock); - goto out_crypto_sysfs_unregister; - } - } wbt_enable_default(disk); mutex_unlock(&q->elevator_lock); @@ -902,8 +896,6 @@ int blk_register_queue(struct gendisk *disk) return ret; -out_crypto_sysfs_unregister: - blk_crypto_sysfs_unregister(disk); out_unregister_ia_ranges: disk_unregister_independent_access_ranges(disk); out_debugfs_remove: @@ -951,9 +943,11 @@ void blk_unregister_queue(struct gendisk *disk) blk_mq_sysfs_unregister(disk); blk_crypto_sysfs_unregister(disk); - mutex_lock(&q->elevator_lock); - elv_unregister_queue(q); - mutex_unlock(&q->elevator_lock); + if (q->elevator) { + blk_mq_quiesce_queue(q); + elevator_set_none(q); + blk_mq_unquiesce_queue(q); + } mutex_lock(&q->sysfs_lock); disk_unregister_independent_access_ranges(disk); diff --git a/block/blk.h b/block/blk.h index 2969f4427996..6ba674d1ceba 100644 --- a/block/blk.h +++ b/block/blk.h @@ -320,9 +320,8 @@ bool blk_bio_list_merge(struct request_queue *q, struct list_head *list, bool blk_insert_flush(struct request *rq); void elv_update_nr_hw_queues(struct request_queue *q); -void elevator_exit(struct request_queue *q); -int elv_register_queue(struct request_queue *q, bool uevent); -void elv_unregister_queue(struct request_queue *q); +void elevator_set_default(struct request_queue *q); +void elevator_set_none(struct request_queue *q); ssize_t part_size_show(struct device *dev, struct device_attribute *attr, char *buf); diff --git a/block/elevator.c b/block/elevator.c index 4be318b0b4ef..5ec66fbd4f24 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -49,6 +49,7 @@ struct elv_change_ctx { const char *name; bool uevent; + bool init; }; static DEFINE_SPINLOCK(elv_list_lock); @@ -154,7 +155,7 @@ static void elevator_release(struct kobject *kobj) kfree(e); } -void elevator_exit(struct request_queue *q) +static void elevator_exit(struct request_queue *q) { struct elevator_queue *e = q->elevator; @@ -458,7 +459,7 @@ static const struct kobj_type elv_ktype = { .release = elevator_release, }; -int elv_register_queue(struct request_queue *q, bool uevent) +static int elv_register_queue(struct request_queue *q, bool uevent) { struct elevator_queue *e = q->elevator; int error; @@ -488,7 +489,7 @@ int elv_register_queue(struct request_queue *q, bool uevent) return error; } -void elv_unregister_queue(struct request_queue *q) +static void elv_unregister_queue(struct request_queue *q) { struct elevator_queue *e = q->elevator; @@ -565,60 +566,16 @@ EXPORT_SYMBOL_GPL(elv_unregister); * For single queue devices, default to using mq-deadline. If we have multiple * queues or mq-deadline is not available, default to "none". */ -static struct elevator_type *elevator_get_default(struct request_queue *q) +static bool use_default_elevator(struct request_queue *q) { if (q->tag_set->flags & BLK_MQ_F_NO_SCHED_BY_DEFAULT) - return NULL; + return false; if (q->nr_hw_queues != 1 && !blk_mq_is_shared_tags(q->tag_set->flags)) - return NULL; - - return elevator_find_get("mq-deadline"); -} - -/* - * Use the default elevator settings. If the chosen elevator initialization - * fails, fall back to the "none" elevator (no elevator). - */ -void elevator_init_mq(struct request_queue *q) -{ - struct elevator_type *e; - unsigned int memflags; - int err; - - WARN_ON_ONCE(blk_queue_registered(q)); - - if (unlikely(q->elevator)) - return; - - e = elevator_get_default(q); - if (!e) - return; - - /* - * We are called before adding disk, when there isn't any FS I/O, - * so freezing queue plus canceling dispatch work is enough to - * drain any dispatch activities originated from passthrough - * requests, then no need to quiesce queue which may add long boot - * latency, especially when lots of disks are involved. - * - * Disk isn't added yet, so verifying queue lock only manually. - */ - memflags = blk_mq_freeze_queue(q); - - blk_mq_cancel_work_sync(q); - - err = blk_mq_init_sched(q, e); - - blk_mq_unfreeze_queue(q, memflags); - - if (err) { - pr_warn("\"%s\" elevator initialization failed, " - "falling back to \"none\"\n", e->elevator_name); - } + return false; - elevator_put(e); + return true; } /* @@ -694,7 +651,7 @@ static int __elevator_change(struct request_queue *q, lockdep_assert_held(&q->tag_set->update_nr_hwq_sema); /* Make sure queue is not in the middle of being removed */ - if (!blk_queue_registered(q)) + if (!ctx->init && !blk_queue_registered(q)) return -ENOENT; if (!strncmp(elevator_name, "none", 4)) { @@ -718,6 +675,16 @@ static int elevator_change(struct request_queue *q, int ret = 0; memflags = blk_mq_freeze_queue(q); + /* + * May be called before adding disk, when there isn't any FS I/O, + * so freezing queue plus canceling dispatch work is enough to + * drain any dispatch activities originated from passthrough + * requests, then no need to quiesce queue which may add long boot + * latency, especially when lots of disks are involved. + * + * Disk isn't added yet, so verifying queue lock only manually. + */ + blk_mq_cancel_work_sync(q); mutex_lock(&q->elevator_lock); if (!q->elevator || !elevator_match(q->elevator->type, ctx->name)) ret = __elevator_change(q, ctx); @@ -726,6 +693,49 @@ static int elevator_change(struct request_queue *q, return ret; } +/* + * Use the default elevator settings. If the chosen elevator initialization + * fails, fall back to the "none" elevator (no elevator). + */ +void elevator_set_default(struct request_queue *q) +{ + struct elv_change_ctx ctx = { + .init = true, + }; + int err; + + if (!queue_is_mq(q)) + return; + + ctx.name = use_default_elevator(q) ? "mq-deadline" : "none"; + if (!q->elevator && !strcmp(ctx.name, "none")) + return; + err = elevator_change(q, &ctx); + if (err < 0) + pr_warn("\"%s\" set elevator failed %d, " + "falling back to \"none\"\n", ctx.name, err); +} + +void elevator_set_none(struct request_queue *q) +{ + struct elv_change_ctx ctx = { + .name = "none", + .uevent = true, + .init = true, + }; + int err; + + if (!queue_is_mq(q)) + return; + + if (!q->elevator) + return; + + err = elevator_change(q, &ctx); + if (err < 0) + pr_warn("%s: set none elevator failed %d\n", __func__, err); +} + /* * The I/O scheduler depends on the number of hardware queues, this forces a * reattachment when nr_hw_queues changes. diff --git a/block/genhd.c b/block/genhd.c index 53c5b1e9e1d2..a50063c4c40f 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -416,12 +416,6 @@ static int __add_disk_fwnode(struct device *parent, struct gendisk *disk, */ if (disk->fops->submit_bio || disk->fops->poll_bio) return -EINVAL; - - /* - * Initialize the I/O scheduler code and pick a default one if - * needed. - */ - elevator_init_mq(disk->queue); } else { if (!disk->fops->submit_bio) return -EINVAL; @@ -438,7 +432,7 @@ static int __add_disk_fwnode(struct device *parent, struct gendisk *disk, ret = -EINVAL; if (disk->major) { if (WARN_ON(!disk->minors)) - goto out_exit_elevator; + goto out; if (disk->minors > DISK_MAX_PARTS) { pr_err("block: can't allocate more than %d partitions\n", @@ -448,14 +442,14 @@ static int __add_disk_fwnode(struct device *parent, struct gendisk *disk, if (disk->first_minor > MINORMASK || disk->minors > MINORMASK + 1 || disk->first_minor + disk->minors > MINORMASK + 1) - goto out_exit_elevator; + goto out; } else { if (WARN_ON(disk->minors)) - goto out_exit_elevator; + goto out; ret = blk_alloc_ext_minor(); if (ret < 0) - goto out_exit_elevator; + goto out; disk->major = BLOCK_EXT_MAJOR; disk->first_minor = ret; } @@ -564,12 +558,7 @@ static int __add_disk_fwnode(struct device *parent, struct gendisk *disk, out_free_ext_minor: if (disk->major == BLOCK_EXT_MAJOR) blk_free_ext_minor(disk->first_minor); -out_exit_elevator: - if (disk->queue->elevator) { - mutex_lock(&disk->queue->elevator_lock); - elevator_exit(disk->queue); - mutex_unlock(&disk->queue->elevator_lock); - } +out: return ret; } @@ -755,14 +744,7 @@ static void __del_gendisk(struct gendisk *disk) if (queue_is_mq(q)) blk_mq_cancel_work_sync(q); - blk_mq_quiesce_queue(q); - if (q->elevator) { - mutex_lock(&q->elevator_lock); - elevator_exit(q); - mutex_unlock(&q->elevator_lock); - } rq_qos_exit(q); - blk_mq_unquiesce_queue(q); /* * If the disk does not own the queue, allow using passthrough requests -- 2.47.0