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Wong" , Dave Kleikamp , David Sterba , dm-devel@redhat.com, drbd-dev@lists.linbit.com, Gao Xiang , Jack Wang , Jaegeuk Kim , jfs-discussion@lists.sourceforge.net, Joern Engel , Joseph Qi , Kent Overstreet , linux-bcache@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mm@kvack.org, linux-mtd@lists.infradead.org, linux-nfs@vger.kernel.org, linux-nilfs@vger.kernel.org, linux-nvme@lists.infradead.org, linux-pm@vger.kernel.org, linux-raid@vger.kernel.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, linux-xfs@vger.kernel.org, "Md. Haris Iqbal" , Mike Snitzer , Minchan Kim , ocfs2-devel@oss.oracle.com, reiserfs-devel@vger.kernel.org, Sergey Senozhatsky , Song Liu , Sven Schnelle , target-devel@vger.kernel.org, Ted Tso , Trond Myklebust , xen-devel@lists.xenproject.org Subject: Re: [PATCH 01/32] block: Provide blkdev_get_handle_* functions Message-ID: <20230705161225.cwig5a3mo6oz7lew@quack3> References: <20230629165206.383-1-jack@suse.cz> <20230704122224.16257-1-jack@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Stat-Signature: w9fqfgju8rkxafzgkda7koya39ijiu5n X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 8A090140021 X-HE-Tag: 1688573547-668800 X-HE-Meta: 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 QVtdHHoT 0ki77AJqjKJ/SyzGJ56NLUQZaFrzIDNEZJm97VPpkKGyS37K5oSx9WYmmVgfW+UCT1aJImeHe7TyrLSlbd1phqZq2G2/1ANSnYPRxBPfAwlwEHaeBnRKNEar+G3GvSTJKOGrQqfM62Y54idu4/K0DbUkd0EsqfAnmnkCoUKG7ykzB7ut/EtdHATQVNjBg+lKI+K+w0PKYgMr7v2qvRyLglUdaWCcn/O8V2Ijqq7/0l5DU5KE198cdLmRpxqhtL9X5CZL5Sp3lEmopOrMfPS2YN3YFLzP4EEEDno36926oQVsDj3O+m4AFAdy2ys17FM0SUiCydgUA/SEh94wkSfBqh/4TZLD1cxLDSGsVxo7A1s4u5j5fDBz/wkALCw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue 04-07-23 07:06:26, Bart Van Assche wrote: > On 7/4/23 05:21, Jan Kara wrote: > > +struct bdev_handle { > > + struct block_device *bdev; > > + void *holder; > > +}; > > Please explain in the patch description why a holder pointer is introduced > in struct bdev_handle and how it relates to the bd_holder pointer in struct > block_device. Is one of the purposes of this patch series perhaps to add > support for multiple holders per block device? No. The reason for adding holder to struct bdev_handle is that it is an argument blkdev_put() needs. Currently, every user of blkdev_put() has to remember what it has passed as 'holder' to blkdev_get_by_*() call and pass that to blkdev_put(). With struct bdev_handle this will happen automatically. This is already explained in the changelog of this patch: "Create struct bdev_handle that contains all parameters that need to be passed to blkdev_put()..." If it was only about holder, the intrusive patches would not be warranted but as the description also says: "This will eventually allow us to pass one more argument to blkdev_put() without too much hassle." Because we will additionaly need to propagate the 'mode' argument used at open to blkdev_put(). Honza -- Jan Kara SUSE Labs, CR