From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 D41246AD3 for ; Wed, 30 Apr 2025 04:36:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745987816; cv=none; b=bkdf+CdEz7qB/Z7W94lr+Ppbju1VWLR7jlXNXRi8JLaoArrP6b55icEp94mFJwQxX32h+wwquVvVU+oefIE/NVdv3+KgP5PTdYoh7whtuwcvTdAVtiZ+DGCfT5fpXGzLspB9blurttPiIS8KzMA3j0Ve7y6YsXrhX5GTkZPAtLI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745987816; c=relaxed/simple; bh=lLp/zvCSF3z8mKV/vGt/lEgTcp5rtC5qH5G4Y45nj8o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qbqNwK8NvuYPuq09tQQj2kBxQ+ka6lk6mobi36Rd6d/zGGqxTb06qdQzYMy+7FkBzMVRMuLBbBC9tZNjEBG4+lYRltmMvEPlesxqDRiOJkQbiOdmoDiJRGvzrPZ3AS/a9k2U+EGaUEwsIuxSHkQzCbTQeOG5LfxBklsitK4/8JI= 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=G5qXwyGM; arc=none smtp.client-ip=170.10.129.124 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="G5qXwyGM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1745987814; 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=uW1xJyGNL9QmmsmxIVPgMBVHL+60OC6//Qctal1wdq0=; b=G5qXwyGMFce1+dv8Yb3qW37zuqbRrUBGtml2aMBjyc2ulpX5kvXXIKQxrGGPAYwgq8yCxi CevIaRnFv7ZvnnF2x48MJfGiMZLW5iygatfP0fMVIHt+oKAHN1g7cSUXOAziKpJpqOr8nw Q8bO+KHMXBMjBtQqH+/AuLqD6sf/Y0w= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-103-fRBPCwg4Pk2HK-ExXBCaIg-1; Wed, 30 Apr 2025 00:36:49 -0400 X-MC-Unique: fRBPCwg4Pk2HK-ExXBCaIg-1 X-Mimecast-MFC-AGG-ID: fRBPCwg4Pk2HK-ExXBCaIg_1745987808 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 919771956095; Wed, 30 Apr 2025 04:36:48 +0000 (UTC) Received: from localhost (unknown [10.72.116.48]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 91CB730001A2; Wed, 30 Apr 2025 04:36:47 +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 V4 19/24] block: add new helper for disabling elevator switch when deleting disk Date: Wed, 30 Apr 2025 12:35:21 +0800 Message-ID: <20250430043529.1950194-20-ming.lei@redhat.com> In-Reply-To: <20250430043529.1950194-1-ming.lei@redhat.com> References: <20250430043529.1950194-1-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 10.30.177.4 Add new helper disable_elv_switch() and new flag QUEUE_FLAG_NO_ELV_SWITCH for disabling elevator switch before deleting disk: - originally flag QUEUE_FLAG_REGISTERED is added for preventing elevator switch during removing disk, but this flag has been used widely for other purposes, so add one new flag for disabling elevator switch only - for avoiding deadlock risk, we have to move elevator queue register/unregister out of elevator lock and queue freeze, which will be done in next patch. However, this way adds small race window between elevator switch and deleting ->queue_kobj, in which elevator queue register/unregister could be run concurrently. The added helper will be used for avoiding the race in the following patch. Signed-off-by: Ming Lei --- block/blk-mq-debugfs.c | 1 + block/elevator.c | 5 ++++- block/genhd.c | 12 ++++++++++++ include/linux/blkdev.h | 3 +++ 4 files changed, 20 insertions(+), 1 deletion(-) diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c index 2837a8ce8054..29b3540dd180 100644 --- a/block/blk-mq-debugfs.c +++ b/block/blk-mq-debugfs.c @@ -94,6 +94,7 @@ static const char *const blk_queue_flag_name[] = { QUEUE_FLAG_NAME(HCTX_ACTIVE), QUEUE_FLAG_NAME(SQ_SCHED), QUEUE_FLAG_NAME(DISABLE_WBT_DEF), + QUEUE_FLAG_NAME(NO_ELV_SWITCH), }; #undef QUEUE_FLAG_NAME diff --git a/block/elevator.c b/block/elevator.c index fd0bcf22aaee..98a754f58de5 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -680,6 +680,9 @@ void elevator_set_default(struct request_queue *q) }; int err = 0; + /* now we allow to switch elevator */ + blk_queue_flag_clear(QUEUE_FLAG_NO_ELV_SWITCH, q); + if (q->tag_set->flags & BLK_MQ_F_NO_SCHED_BY_DEFAULT) return; @@ -730,7 +733,7 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf, struct blk_mq_tag_set *set = q->tag_set; /* Make sure queue is not in the middle of being removed */ - if (!blk_queue_registered(q)) + if (!blk_queue_registered(q) || blk_queue_no_elv_switch(q)) return -ENOENT; /* diff --git a/block/genhd.c b/block/genhd.c index 0c34cc1a4eae..0e64e7400fb4 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -749,6 +749,15 @@ static void __del_gendisk(struct gendisk *disk) blk_unfreeze_release_lock(q); } +static void disable_elv_switch(struct request_queue *q) +{ + WARN_ON_ONCE(!queue_is_mq(q)); + + mutex_lock(&q->elevator_lock); + blk_queue_flag_set(QUEUE_FLAG_NO_ELV_SWITCH, q); + mutex_unlock(&q->elevator_lock); +} + /** * del_gendisk - remove the gendisk * @disk: the struct gendisk to remove @@ -777,6 +786,9 @@ void del_gendisk(struct gendisk *disk) __del_gendisk(disk); } else { set = disk->queue->tag_set; + + disable_elv_switch(disk->queue); + memflags = memalloc_noio_save(); down_read(&set->update_nr_hwq_lock); __del_gendisk(disk); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 9c373cf0eb47..b15c53fabe9f 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -645,6 +645,7 @@ enum { QUEUE_FLAG_HCTX_ACTIVE, /* at least one blk-mq hctx is active */ QUEUE_FLAG_SQ_SCHED, /* single queue style io dispatch */ QUEUE_FLAG_DISABLE_WBT_DEF, /* for sched to disable/enable wbt */ + QUEUE_FLAG_NO_ELV_SWITCH, /* can't switch elevator any more */ QUEUE_FLAG_MAX }; @@ -682,6 +683,8 @@ void blk_queue_flag_clear(unsigned int flag, struct request_queue *q); ((q)->limits.features & BLK_FEAT_SKIP_TAGSET_QUIESCE) #define blk_queue_disable_wbt(q) \ test_bit(QUEUE_FLAG_DISABLE_WBT_DEF, &(q)->queue_flags) +#define blk_queue_no_elv_switch(q) \ + test_bit(QUEUE_FLAG_NO_ELV_SWITCH, &(q)->queue_flags) extern void blk_set_pm_only(struct request_queue *q); extern void blk_clear_pm_only(struct request_queue *q); -- 2.47.0