From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88D7AC2D0E4 for ; Tue, 24 Nov 2020 13:32:20 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id ED55F2076E for ; Tue, 24 Nov 2020 13:32:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ED55F2076E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=tempfail smtp.mailfrom=dm-devel-bounces@redhat.com Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-546-gMehbd07Pw-6e2RGirVTqg-1; Tue, 24 Nov 2020 08:32:16 -0500 X-MC-Unique: gMehbd07Pw-6e2RGirVTqg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6146E107ACFE; Tue, 24 Nov 2020 13:32:12 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 42F0260C4D; Tue, 24 Nov 2020 13:32:12 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 163E45002E; Tue, 24 Nov 2020 13:32:12 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 0AODW9av018727 for ; Tue, 24 Nov 2020 08:32:10 -0500 Received: by smtp.corp.redhat.com (Postfix) id DA7CC1112869; Tue, 24 Nov 2020 13:32:09 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast06.extmail.prod.ext.rdu2.redhat.com [10.11.55.22]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D55A71003330 for ; Tue, 24 Nov 2020 13:32:07 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7DB0A185A7BC for ; Tue, 24 Nov 2020 13:32:07 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-163-EWr9hmz4PiaK-blQHih17g-1; Tue, 24 Nov 2020 08:32:02 -0500 X-MC-Unique: EWr9hmz4PiaK-blQHih17g-1 Received: from [2001:4bb8:180:5443:c70:4a89:bc61:3] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1khYMs-0006Z8-1F; Tue, 24 Nov 2020 13:28:26 +0000 From: Christoph Hellwig To: Jens Axboe Date: Tue, 24 Nov 2020 14:27:27 +0100 Message-Id: <20201124132751.3747337-22-hch@lst.de> In-Reply-To: <20201124132751.3747337-1-hch@lst.de> References: <20201124132751.3747337-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-loop: dm-devel@redhat.com Cc: linux-bcache@vger.kernel.org, Jan Kara , linux-fsdevel@vger.kernel.org, Mike Snitzer , Konrad Rzeszutek Wilk , Greg Kroah-Hartman , Jan Kara , Josef Bacik , Coly Li , linux-block@vger.kernel.org, Richard Weinberger , dm-devel@redhat.com, linux-mtd@lists.infradead.org, Johannes Thumshirn , Tejun Heo , xen-devel@lists.xenproject.org, linux-mm@kvack.org Subject: [dm-devel] [PATCH 21/45] block: refactor blkdev_get X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Move more code that is only run on the outer open but not the open of the underlying whole device when opening a partition into blkdev_get, which leads to a much easier to follow structure. This allows to simplify the disk and module refcounting so that one reference is held for each open, similar to what we do with normal file operations. Signed-off-by: Christoph Hellwig --- fs/block_dev.c | 185 +++++++++++++++++++++++-------------------------- 1 file changed, 86 insertions(+), 99 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 88847839ef0102..2ffa11a95f10db 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1403,46 +1403,12 @@ EXPORT_SYMBOL_GPL(bdev_disk_changed); * mutex_lock(part->bd_mutex) * mutex_lock_nested(whole->bd_mutex, 1) */ - -static int __blkdev_get(struct block_device *bdev, fmode_t mode, void *holder, - int for_part) +static int __blkdev_get(struct block_device *bdev, struct gendisk *disk, + int partno, fmode_t mode) { - struct block_device *whole = NULL, *claiming = NULL; - struct gendisk *disk; int ret; - int partno; - bool first_open = false, unblock_events = true, need_restart; - - restart: - need_restart = false; - ret = -ENXIO; - disk = bdev_get_gendisk(bdev, &partno); - if (!disk) - goto out; - - if (partno) { - whole = bdget_disk(disk, 0); - if (!whole) { - ret = -ENOMEM; - goto out_put_disk; - } - } - if (!for_part && (mode & FMODE_EXCL)) { - WARN_ON_ONCE(!holder); - if (whole) - claiming = whole; - else - claiming = bdev; - ret = bd_prepare_to_claim(bdev, claiming, holder); - if (ret) - goto out_put_whole; - } - - disk_block_events(disk); - mutex_lock_nested(&bdev->bd_mutex, for_part); if (!bdev->bd_openers) { - first_open = true; bdev->bd_disk = disk; bdev->bd_contains = bdev; bdev->bd_partno = partno; @@ -1454,15 +1420,8 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, void *holder, goto out_clear; ret = 0; - if (disk->fops->open) { + if (disk->fops->open) ret = disk->fops->open(bdev, mode); - /* - * If we lost a race with 'disk' being deleted, - * try again. See md.c - */ - if (ret == -ERESTARTSYS) - need_restart = true; - } if (!ret) { bd_set_nr_sectors(bdev, get_capacity(disk)); @@ -1482,14 +1441,23 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, void *holder, if (ret) goto out_clear; } else { - BUG_ON(for_part); - ret = __blkdev_get(whole, mode, NULL, 1); - if (ret) + struct block_device *whole = bdget_disk(disk, 0); + + mutex_lock_nested(&whole->bd_mutex, 1); + ret = __blkdev_get(whole, disk, 0, mode); + if (ret) { + mutex_unlock(&whole->bd_mutex); + bdput(whole); goto out_clear; - bdev->bd_contains = bdgrab(whole); + } + whole->bd_part_count++; + mutex_unlock(&whole->bd_mutex); + + bdev->bd_contains = whole; bdev->bd_part = disk_get_part(disk, partno); if (!(disk->flags & GENHD_FL_UP) || !bdev->bd_part || !bdev->bd_part->nr_sects) { + __blkdev_put(whole, mode, 1); ret = -ENXIO; goto out_clear; } @@ -1509,58 +1477,17 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, void *holder, (!ret || ret == -ENOMEDIUM)) bdev_disk_changed(bdev, ret == -ENOMEDIUM); if (ret) - goto out_unlock_bdev; + return ret; } } bdev->bd_openers++; - if (for_part) - bdev->bd_part_count++; - if (claiming) - bd_finish_claiming(bdev, claiming, holder); - - /* - * Block event polling for write claims if requested. Any write holder - * makes the write_holder state stick until all are released. This is - * good enough and tracking individual writeable reference is too - * fragile given the way @mode is used in blkdev_get/put(). - */ - if (claiming && (mode & FMODE_WRITE) && !bdev->bd_write_holder && - (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) { - bdev->bd_write_holder = true; - unblock_events = false; - } - mutex_unlock(&bdev->bd_mutex); - - if (unblock_events) - disk_unblock_events(disk); - - /* only one opener holds refs to the module and disk */ - if (!first_open) - put_disk_and_module(disk); - if (whole) - bdput(whole); return 0; out_clear: disk_put_part(bdev->bd_part); bdev->bd_disk = NULL; bdev->bd_part = NULL; - if (bdev != bdev->bd_contains) - __blkdev_put(bdev->bd_contains, mode, 1); bdev->bd_contains = NULL; - out_unlock_bdev: - if (claiming) - bd_abort_claiming(bdev, claiming, holder); - mutex_unlock(&bdev->bd_mutex); - disk_unblock_events(disk); - out_put_whole: - if (whole) - bdput(whole); - out_put_disk: - put_disk_and_module(disk); - if (need_restart) - goto restart; - out: return ret; } @@ -1585,7 +1512,12 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, void *holder, */ static int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) { - int ret, perm = 0; + struct block_device *claiming; + bool unblock_events = true; + struct gendisk *disk; + int perm = 0; + int partno; + int ret; if (mode & FMODE_READ) perm |= MAY_READ; @@ -1595,13 +1527,67 @@ static int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) if (ret) goto bdput; - ret =__blkdev_get(bdev, mode, holder, 0); - if (ret) + /* + * If we lost a race with 'disk' being deleted, try again. See md.c. + */ +retry: + ret = -ENXIO; + disk = bdev_get_gendisk(bdev, &partno); + if (!disk) goto bdput; - return 0; + if (mode & FMODE_EXCL) { + WARN_ON_ONCE(!holder); + + ret = -ENOMEM; + claiming = bdget_disk(disk, 0); + if (!claiming) + goto put_disk; + ret = bd_prepare_to_claim(bdev, claiming, holder); + if (ret) + goto put_claiming; + } + + disk_block_events(disk); + + mutex_lock(&bdev->bd_mutex); + ret =__blkdev_get(bdev, disk, partno, mode); + if (!(mode & FMODE_EXCL)) { + ; /* nothing to do here */ + } else if (ret) { + bd_abort_claiming(bdev, claiming, holder); + } else { + bd_finish_claiming(bdev, claiming, holder); + + /* + * Block event polling for write claims if requested. Any write + * holder makes the write_holder state stick until all are + * released. This is good enough and tracking individual + * writeable reference is too fragile given the way @mode is + * used in blkdev_get/put(). + */ + if ((mode & FMODE_WRITE) && !bdev->bd_write_holder && + (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) { + bdev->bd_write_holder = true; + unblock_events = false; + } + } + mutex_unlock(&bdev->bd_mutex); + + if (unblock_events) + disk_unblock_events(disk); + +put_claiming: + if (mode & FMODE_EXCL) + bdput(claiming); +put_disk: + if (ret) + put_disk_and_module(disk); + if (ret == -ERESTARTSYS) + goto retry; bdput: - bdput(bdev); + if (ret) + bdput(bdev); return ret; } @@ -1749,8 +1735,6 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) if (bdev_is_partition(bdev)) victim = bdev->bd_contains; bdev->bd_contains = NULL; - - put_disk_and_module(disk); } else { if (!bdev_is_partition(bdev) && disk->fops->release) disk->fops->release(disk, mode); @@ -1763,6 +1747,8 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) void blkdev_put(struct block_device *bdev, fmode_t mode) { + struct gendisk *disk = bdev->bd_disk; + mutex_lock(&bdev->bd_mutex); if (mode & FMODE_EXCL) { @@ -1791,7 +1777,7 @@ void blkdev_put(struct block_device *bdev, fmode_t mode) * unblock evpoll if it was a write holder. */ if (bdev_free && bdev->bd_write_holder) { - disk_unblock_events(bdev->bd_disk); + disk_unblock_events(disk); bdev->bd_write_holder = false; } } @@ -1801,11 +1787,12 @@ void blkdev_put(struct block_device *bdev, fmode_t mode) * event. This is to ensure detection of media removal commanded * from userland - e.g. eject(1). */ - disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE); + disk_flush_events(disk, DISK_EVENT_MEDIA_CHANGE); mutex_unlock(&bdev->bd_mutex); __blkdev_put(bdev, mode, 0); + put_disk_and_module(disk); } EXPORT_SYMBOL(blkdev_put); -- 2.29.2 -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel