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From: Sergei Shtepa <sergei.shtepa@veeam.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Mike Snitzer <snitzer@redhat.com>,
	Alasdair Kergon <agk@redhat.com>, Hannes Reinecke <hare@suse.de>,
	Jens Axboe <axboe@kernel.dk>,
	"dm-devel@redhat.com" <dm-devel@redhat.com>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-api@vger.kernel.org" <linux-api@vger.kernel.org>,
	Pavel Tide <Pavel.TIde@veeam.com>
Subject: Re: [PATCH v7 3/3] dm: add DM_INTERPOSED_FLAG
Date: Mon, 15 Mar 2021 16:25:09 +0300	[thread overview]
Message-ID: <20210315132509.GD30489@veeam.com> (raw)
In-Reply-To: <20210314093038.GC3773360@infradead.org>

The 03/14/2021 12:30, Christoph Hellwig wrote:
> On Fri, Mar 12, 2021 at 06:44:55PM +0300, Sergei Shtepa wrote:
> > DM_INTERPOSED_FLAG allow to create DM targets on "the fly".
> > Underlying block device opens without a flag FMODE_EXCL.
> > DM target receives bio from the original device via
> > bdev_interposer.
> 
> This is more of a philopical comment, but the idea of just letting the
> interposed reopen the device by itself seems like a bad idea.  I think
> that is probably better hidden in the block layer interposer attachment
> function, which could do the extra blkdev_get_by_dev for the caller.

I suppose this cannot be implemented, since we need to change the behavior
for block devices that already have been opened.

-- 
Sergei Shtepa
Veeam Software developer.

WARNING: multiple messages have this Message-ID (diff)
From: Sergei Shtepa <sergei.shtepa@veeam.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>, Mike Snitzer <snitzer@redhat.com>,
	"linux-api@vger.kernel.org" <linux-api@vger.kernel.org>,
	Pavel Tide <Pavel.TIde@veeam.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"dm-devel@redhat.com" <dm-devel@redhat.com>,
	Alasdair Kergon <agk@redhat.com>
Subject: Re: [dm-devel] [PATCH v7 3/3] dm: add DM_INTERPOSED_FLAG
Date: Mon, 15 Mar 2021 16:25:09 +0300	[thread overview]
Message-ID: <20210315132509.GD30489@veeam.com> (raw)
In-Reply-To: <20210314093038.GC3773360@infradead.org>

The 03/14/2021 12:30, Christoph Hellwig wrote:
> On Fri, Mar 12, 2021 at 06:44:55PM +0300, Sergei Shtepa wrote:
> > DM_INTERPOSED_FLAG allow to create DM targets on "the fly".
> > Underlying block device opens without a flag FMODE_EXCL.
> > DM target receives bio from the original device via
> > bdev_interposer.
> 
> This is more of a philopical comment, but the idea of just letting the
> interposed reopen the device by itself seems like a bad idea.  I think
> that is probably better hidden in the block layer interposer attachment
> function, which could do the extra blkdev_get_by_dev for the caller.

I suppose this cannot be implemented, since we need to change the behavior
for block devices that already have been opened.

-- 
Sergei Shtepa
Veeam Software developer.

--
dm-devel mailing list
dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel


  reply	other threads:[~2021-03-15 13:26 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-12 15:44 [PATCH v7 0/3] block device interposer Sergei Shtepa
2021-03-12 15:44 ` [dm-devel] " Sergei Shtepa
2021-03-12 15:44 ` [PATCH v7 1/3] block: add blk_mq_is_queue_frozen() Sergei Shtepa
2021-03-12 15:44   ` [dm-devel] " Sergei Shtepa
2021-03-12 19:06   ` Mike Snitzer
2021-03-12 19:06     ` [dm-devel] " Mike Snitzer
2021-03-14  9:14     ` Christoph Hellwig
2021-03-14  9:14       ` [dm-devel] " Christoph Hellwig
2021-03-15 12:06       ` Sergei Shtepa
2021-03-15 12:06         ` [dm-devel] " Sergei Shtepa
2021-03-12 15:44 ` [PATCH v7 2/3] block: add bdev_interposer Sergei Shtepa
2021-03-12 15:44   ` [dm-devel] " Sergei Shtepa
2021-03-14  9:28   ` Christoph Hellwig
2021-03-14  9:28     ` [dm-devel] " Christoph Hellwig
2021-03-15 13:06     ` Sergei Shtepa
2021-03-15 13:06       ` [dm-devel] " Sergei Shtepa
2021-03-16  8:09   ` Ming Lei
2021-03-16  8:09     ` [dm-devel] " Ming Lei
2021-03-16 16:35     ` Sergei Shtepa
2021-03-16 16:35       ` [dm-devel] " Sergei Shtepa
2021-03-17  3:03       ` Ming Lei
2021-03-17  3:03         ` [dm-devel] " Ming Lei
2021-03-17 12:22         ` Sergei Shtepa
2021-03-17 12:22           ` [dm-devel] " Sergei Shtepa
2021-03-17 15:04           ` Mike Snitzer
2021-03-17 15:04             ` [dm-devel] " Mike Snitzer
2021-03-17 18:14             ` Sergei Shtepa
2021-03-17 18:14               ` [dm-devel] " Sergei Shtepa
2021-03-17 19:13               ` Mike Snitzer
2021-03-17 19:13                 ` [dm-devel] " Mike Snitzer
2021-03-18 14:56                 ` Sergei Shtepa
2021-03-18 14:56                   ` [dm-devel] " Sergei Shtepa
2021-03-17 14:58         ` Mike Snitzer
2021-03-17 14:58           ` [dm-devel] " Mike Snitzer
2021-03-12 15:44 ` [PATCH v7 3/3] dm: add DM_INTERPOSED_FLAG Sergei Shtepa
2021-03-12 15:44   ` [dm-devel] " Sergei Shtepa
2021-03-12 19:00   ` Mike Snitzer
2021-03-12 19:00     ` [dm-devel] " Mike Snitzer
2021-03-15 12:29     ` Sergei Shtepa
2021-03-15 12:29       ` [dm-devel] " Sergei Shtepa
2021-03-14  9:30   ` Christoph Hellwig
2021-03-14  9:30     ` [dm-devel] " Christoph Hellwig
2021-03-15 13:25     ` Sergei Shtepa [this message]
2021-03-15 13:25       ` Sergei Shtepa
2021-03-16 15:23       ` Christoph Hellwig
2021-03-16 15:23         ` [dm-devel] " Christoph Hellwig
2021-03-16 15:25         ` Christoph Hellwig
2021-03-16 15:25           ` [dm-devel] " Christoph Hellwig
2021-03-16 16:20           ` Sergei Shtepa
2021-03-16 16:20             ` [dm-devel] " Sergei Shtepa

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