From: "hch@infradead.org" <hch@infradead.org>
To: Mike Snitzer <snitzer@redhat.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
Sergei Shtepa <sergei.shtepa@veeam.com>,
Damien Le Moal <Damien.LeMoal@wdc.com>,
Hannes Reinecke <hare@suse.de>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
"hch@infradead.org" <hch@infradead.org>,
"linux-xfs@vger.kernel.org" <linux-xfs@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"rjw@rjwysocki.net" <rjw@rjwysocki.net>,
"len.brown@intel.com" <len.brown@intel.com>,
"pavel@ucw.cz" <pavel@ucw.cz>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
Johannes Thumshirn <Johannes.Thumshirn@wdc.com>,
"ming.lei@redhat.com" <ming.lei@redhat.com>,
"jack@suse.cz" <jack@suse.cz>, "tj@kernel.org" <tj@kernel.org>,
"gustavo@embeddedor.com" <gustavo@embeddedor.com>,
"bvanassche@acm.org" <bvanassche@acm.org>,
"osandov@fb.com" <osandov@fb.com>,
"koct9i@gmail.com" <koct9i@gmail.com>,
"steve@sk2.org" <steve@sk2.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
device-mapper development <dm-devel@redhat.com>,
Alasdair G Kergon <agk@redhat.com>
Subject: Re: [PATCH 0/2] block layer filter and block device snapshot module
Date: Fri, 23 Oct 2020 10:13:46 +0100 [thread overview]
Message-ID: <20201023091346.GA25115@infradead.org> (raw)
In-Reply-To: <CAMM=eLfO_L-ZzcGmpPpHroznnSOq_KEWignFoM09h7Am9yE83g@mail.gmail.com>
On Thu, Oct 22, 2020 at 01:54:16PM -0400, Mike Snitzer wrote:
> On Thu, Oct 22, 2020 at 11:14 AM Darrick J. Wong
> > Stupid question: Why don't you change the block layer to make it
> > possible to insert device mapper devices after the blockdev has been set
> > up?
>
> Not a stupid question. Definitely something that us DM developers
> have wanted to do for a while. Devil is in the details but it is the
> right way forward.
>
Yes, I think that is the right thing to do. And I don't think it should
be all that hard. All we'd need in the I/O path is something like the
pseudo-patch below, which will allow the interposer driver to resubmit
bios using submit_bio_noacct as long as the driver sets BIO_INTERPOSED.
diff --git a/block/blk-core.c b/block/blk-core.c
index ac00d2fa4eb48d..3f6f1eb565e0a8 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1051,6 +1051,9 @@ blk_qc_t submit_bio_noacct(struct bio *bio)
return BLK_QC_T_NONE;
}
+ if (blk_has_interposer(bio->bi_disk) &&
+ !(bio->bi_flags & BIO_INTERPOSED))
+ return __submit_bio_interposed(bio);
if (!bio->bi_disk->fops->submit_bio)
return __submit_bio_noacct_mq(bio);
return __submit_bio_noacct(bio);
WARNING: multiple messages have this Message-ID (diff)
From: "hch@infradead.org" <hch@infradead.org>
To: Mike Snitzer <snitzer@redhat.com>
Cc: "jack@suse.cz" <jack@suse.cz>,
"gustavo@embeddedor.com" <gustavo@embeddedor.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
device-mapper development <dm-devel@redhat.com>,
"pavel@ucw.cz" <pavel@ucw.cz>, "steve@sk2.org" <steve@sk2.org>,
"osandov@fb.com" <osandov@fb.com>,
Alasdair G Kergon <agk@redhat.com>,
"bvanassche@acm.org" <bvanassche@acm.org>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
"hch@infradead.org" <hch@infradead.org>,
"len.brown@intel.com" <len.brown@intel.com>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
"ming.lei@redhat.com" <ming.lei@redhat.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
Sergei Shtepa <sergei.shtepa@veeam.com>,
"koct9i@gmail.com" <koct9i@gmail.com>,
"axboe@kernel.dk" <axboe@kernel.dk>,
Damien Le Moal <Damien.LeMoal@wdc.com>,
Johannes Thumshirn <Johannes.Thumshirn@wdc.com>,
"rjw@rjwysocki.net" <rjw@rjwysocki.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-xfs@vger.kernel.org" <linux-xfs@vger.kernel.org>,
"tj@kernel.org" <tj@kernel.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Subject: Re: [dm-devel] [PATCH 0/2] block layer filter and block device snapshot module
Date: Fri, 23 Oct 2020 10:13:46 +0100 [thread overview]
Message-ID: <20201023091346.GA25115@infradead.org> (raw)
In-Reply-To: <CAMM=eLfO_L-ZzcGmpPpHroznnSOq_KEWignFoM09h7Am9yE83g@mail.gmail.com>
On Thu, Oct 22, 2020 at 01:54:16PM -0400, Mike Snitzer wrote:
> On Thu, Oct 22, 2020 at 11:14 AM Darrick J. Wong
> > Stupid question: Why don't you change the block layer to make it
> > possible to insert device mapper devices after the blockdev has been set
> > up?
>
> Not a stupid question. Definitely something that us DM developers
> have wanted to do for a while. Devil is in the details but it is the
> right way forward.
>
Yes, I think that is the right thing to do. And I don't think it should
be all that hard. All we'd need in the I/O path is something like the
pseudo-patch below, which will allow the interposer driver to resubmit
bios using submit_bio_noacct as long as the driver sets BIO_INTERPOSED.
diff --git a/block/blk-core.c b/block/blk-core.c
index ac00d2fa4eb48d..3f6f1eb565e0a8 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1051,6 +1051,9 @@ blk_qc_t submit_bio_noacct(struct bio *bio)
return BLK_QC_T_NONE;
}
+ if (blk_has_interposer(bio->bi_disk) &&
+ !(bio->bi_flags & BIO_INTERPOSED))
+ return __submit_bio_interposed(bio);
if (!bio->bi_disk->fops->submit_bio)
return __submit_bio_noacct_mq(bio);
return __submit_bio_noacct(bio);
--
dm-devel mailing list
dm-devel@redhat.com
https://www.redhat.com/mailman/listinfo/dm-devel
next prev parent reply other threads:[~2020-10-23 9:14 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-21 9:04 [PATCH 0/2] block layer filter and block device snapshot module Sergei Shtepa
2020-10-21 9:04 ` [PATCH 1/2] Block layer filter - second version Sergei Shtepa
2020-10-21 9:14 ` Johannes Thumshirn
2020-10-21 10:01 ` Sergei Shtepa
2020-10-21 9:21 ` Damien Le Moal
2020-10-21 10:27 ` Sergei Shtepa
2020-10-21 11:44 ` Matthew Wilcox
2020-10-21 12:55 ` Sergei Shtepa
2020-10-21 13:07 ` Matthew Wilcox
2020-10-21 14:35 ` Sergei Shtepa
2020-10-21 15:09 ` Randy Dunlap
2020-10-24 14:53 ` Greg KH
2020-10-21 9:04 ` [PATCH 2/2] blk-snap - snapshots and change-tracking for block devices Sergei Shtepa
2020-10-21 9:08 ` Pavel Machek
2020-10-21 9:37 ` Sergei Shtepa
2020-10-21 9:23 ` Damien Le Moal
2020-10-21 11:15 ` Sergei Shtepa
2020-10-21 10:48 ` kernel test robot
2020-10-21 10:48 ` kernel test robot
2020-10-21 15:11 ` Randy Dunlap
2020-10-21 13:31 ` [PATCH 0/2] block layer filter and block device snapshot module Hannes Reinecke
2020-10-21 14:10 ` Sergei Shtepa
2020-10-22 5:58 ` Hannes Reinecke
2020-10-22 9:44 ` Sergei Shtepa
2020-10-22 10:28 ` Damien Le Moal
2020-10-22 13:52 ` Sergei Shtepa
2020-10-22 15:14 ` Darrick J. Wong
2020-10-22 17:54 ` Mike Snitzer
2020-10-22 17:54 ` [dm-devel] " Mike Snitzer
2020-10-22 17:54 ` Mike Snitzer
2020-10-23 9:13 ` hch [this message]
2020-10-23 9:13 ` [dm-devel] " hch
2020-10-23 10:31 ` Hannes Reinecke
2020-10-23 10:31 ` [dm-devel] " Hannes Reinecke
2020-10-23 11:04 ` Sergei Shtepa
2020-10-23 11:04 ` [dm-devel] " Sergei Shtepa
2020-10-23 11:12 ` hch
2020-10-23 11:12 ` hch
2020-10-22 18:35 ` Mike Snitzer
2020-10-22 18:35 ` [dm-devel] " Mike Snitzer
2020-10-22 18:35 ` Mike Snitzer
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