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=-15.2 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,USER_AGENT_SANE_1 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 F36A3C2D0E4 for ; Thu, 19 Nov 2020 10:07:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A9D9D246CE for ; Thu, 19 Nov 2020 10:07:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726738AbgKSKHe (ORCPT ); Thu, 19 Nov 2020 05:07:34 -0500 Received: from mx2.suse.de ([195.135.220.15]:33374 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726636AbgKSKHe (ORCPT ); Thu, 19 Nov 2020 05:07:34 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3BBD2B114; Thu, 19 Nov 2020 10:07:31 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id E777D1E130B; Thu, 19 Nov 2020 11:07:30 +0100 (CET) Date: Thu, 19 Nov 2020 11:07:30 +0100 From: Jan Kara To: Christoph Hellwig Cc: Jens Axboe , Tejun Heo , Josef Bacik , Konrad Rzeszutek Wilk , Coly Li , Mike Snitzer , dm-devel@redhat.com, Richard Weinberger , Jan Kara , linux-block@vger.kernel.org, xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 12/20] block: simplify the block device claiming interface Message-ID: <20201119100730.GU1981@quack2.suse.cz> References: <20201118084800.2339180-1-hch@lst.de> <20201118084800.2339180-13-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201118084800.2339180-13-hch@lst.de> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed 18-11-20 09:47:52, Christoph Hellwig wrote: > Stop passing the whole device as a separate argument given that it > can be trivially deducted. > > Signed-off-by: Christoph Hellwig The patch looks good to me. You can add: Reviewed-by: Jan Kara Honza > --- > drivers/block/loop.c | 12 +++----- > fs/block_dev.c | 69 +++++++++++++++++++----------------------- > include/linux/blkdev.h | 6 ++-- > 3 files changed, 38 insertions(+), 49 deletions(-) > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index b42c728620c9e4..599e94a7e69259 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -1071,7 +1071,6 @@ static int loop_configure(struct loop_device *lo, fmode_t mode, > struct file *file; > struct inode *inode; > struct address_space *mapping; > - struct block_device *claimed_bdev = NULL; > int error; > loff_t size; > bool partscan; > @@ -1090,8 +1089,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode, > * here to avoid changing device under exclusive owner. > */ > if (!(mode & FMODE_EXCL)) { > - claimed_bdev = bdev->bd_contains; > - error = bd_prepare_to_claim(bdev, claimed_bdev, loop_configure); > + error = bd_prepare_to_claim(bdev, loop_configure); > if (error) > goto out_putf; > } > @@ -1178,15 +1176,15 @@ static int loop_configure(struct loop_device *lo, fmode_t mode, > mutex_unlock(&loop_ctl_mutex); > if (partscan) > loop_reread_partitions(lo, bdev); > - if (claimed_bdev) > - bd_abort_claiming(bdev, claimed_bdev, loop_configure); > + if (!(mode & FMODE_EXCL)) > + bd_abort_claiming(bdev, loop_configure); > return 0; > > out_unlock: > mutex_unlock(&loop_ctl_mutex); > out_bdev: > - if (claimed_bdev) > - bd_abort_claiming(bdev, claimed_bdev, loop_configure); > + if (!(mode & FMODE_EXCL)) > + bd_abort_claiming(bdev, loop_configure); > out_putf: > fput(file); > out: > diff --git a/fs/block_dev.c b/fs/block_dev.c > index e94633dc6ad93b..dd52dbd266cde7 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -110,24 +110,20 @@ EXPORT_SYMBOL(invalidate_bdev); > int truncate_bdev_range(struct block_device *bdev, fmode_t mode, > loff_t lstart, loff_t lend) > { > - struct block_device *claimed_bdev = NULL; > - int err; > - > /* > * If we don't hold exclusive handle for the device, upgrade to it > * while we discard the buffer cache to avoid discarding buffers > * under live filesystem. > */ > if (!(mode & FMODE_EXCL)) { > - claimed_bdev = bdev->bd_contains; > - err = bd_prepare_to_claim(bdev, claimed_bdev, > - truncate_bdev_range); > + int err = bd_prepare_to_claim(bdev, truncate_bdev_range); > if (err) > return err; > } > + > truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend); > - if (claimed_bdev) > - bd_abort_claiming(bdev, claimed_bdev, truncate_bdev_range); > + if (!(mode & FMODE_EXCL)) > + bd_abort_claiming(bdev, truncate_bdev_range); > return 0; > } > EXPORT_SYMBOL(truncate_bdev_range); > @@ -1047,7 +1043,6 @@ static bool bd_may_claim(struct block_device *bdev, struct block_device *whole, > /** > * bd_prepare_to_claim - claim a block device > * @bdev: block device of interest > - * @whole: the whole device containing @bdev, may equal @bdev > * @holder: holder trying to claim @bdev > * > * Claim @bdev. This function fails if @bdev is already claimed by another > @@ -1057,9 +1052,10 @@ static bool bd_may_claim(struct block_device *bdev, struct block_device *whole, > * RETURNS: > * 0 if @bdev can be claimed, -EBUSY otherwise. > */ > -int bd_prepare_to_claim(struct block_device *bdev, struct block_device *whole, > - void *holder) > +int bd_prepare_to_claim(struct block_device *bdev, void *holder) > { > + struct block_device *whole = bdev->bd_contains; > + > retry: > spin_lock(&bdev_lock); > /* if someone else claimed, fail */ > @@ -1099,15 +1095,15 @@ static void bd_clear_claiming(struct block_device *whole, void *holder) > /** > * bd_finish_claiming - finish claiming of a block device > * @bdev: block device of interest > - * @whole: whole block device > * @holder: holder that has claimed @bdev > * > * Finish exclusive open of a block device. Mark the device as exlusively > * open by the holder and wake up all waiters for exclusive open to finish. > */ > -static void bd_finish_claiming(struct block_device *bdev, > - struct block_device *whole, void *holder) > +static void bd_finish_claiming(struct block_device *bdev, void *holder) > { > + struct block_device *whole = bdev->bd_contains; > + > spin_lock(&bdev_lock); > BUG_ON(!bd_may_claim(bdev, whole, holder)); > /* > @@ -1132,11 +1128,10 @@ static void bd_finish_claiming(struct block_device *bdev, > * also used when exclusive open is not actually desired and we just needed > * to block other exclusive openers for a while. > */ > -void bd_abort_claiming(struct block_device *bdev, struct block_device *whole, > - void *holder) > +void bd_abort_claiming(struct block_device *bdev, void *holder) > { > spin_lock(&bdev_lock); > - bd_clear_claiming(whole, holder); > + bd_clear_claiming(bdev->bd_contains, holder); > spin_unlock(&bdev_lock); > } > EXPORT_SYMBOL(bd_abort_claiming); > @@ -1434,7 +1429,7 @@ static void put_disk_and_module(struct gendisk *disk) > static int __blkdev_get(struct block_device *bdev, fmode_t mode, void *holder, > int for_part) > { > - struct block_device *whole = NULL, *claiming = NULL; > + struct block_device *whole = NULL; > struct gendisk *disk = bdev->bd_disk; > int ret; > bool first_open = false, unblock_events = true, need_restart; > @@ -1462,11 +1457,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, void *holder, > > 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); > + ret = bd_prepare_to_claim(bdev, holder); > if (ret) > goto out_put_whole; > } > @@ -1543,21 +1534,23 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, void *holder, > } > } > bdev->bd_openers++; > - if (for_part) > + if (for_part) { > bdev->bd_part_count++; > - if (claiming) > - bd_finish_claiming(bdev, claiming, holder); > + } else if (mode & FMODE_EXCL) { > + bd_finish_claiming(bdev, 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; > + /* > + * 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); > > @@ -1578,8 +1571,8 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, void *holder, > __blkdev_put(bdev->bd_contains, mode, 1); > bdev->bd_contains = NULL; > out_unlock_bdev: > - if (claiming) > - bd_abort_claiming(bdev, claiming, holder); > + if (!for_part && (mode & FMODE_EXCL)) > + bd_abort_claiming(bdev, holder); > mutex_unlock(&bdev->bd_mutex); > disk_unblock_events(disk); > out_put_whole: > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h > index 044d9dd159d882..696b2f9c5529d8 100644 > --- a/include/linux/blkdev.h > +++ b/include/linux/blkdev.h > @@ -1988,10 +1988,8 @@ void blkdev_show(struct seq_file *seqf, off_t offset); > struct block_device *blkdev_get_by_path(const char *path, fmode_t mode, > void *holder); > struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder); > -int bd_prepare_to_claim(struct block_device *bdev, struct block_device *whole, > - void *holder); > -void bd_abort_claiming(struct block_device *bdev, struct block_device *whole, > - void *holder); > +int bd_prepare_to_claim(struct block_device *bdev, void *holder); > +void bd_abort_claiming(struct block_device *bdev, void *holder); > void blkdev_put(struct block_device *bdev, fmode_t mode); > > struct block_device *bdev_alloc(struct gendisk *disk, u8 partno); > -- > 2.29.2 > -- Jan Kara SUSE Labs, CR