From: Mike Snitzer <snitzer@redhat.com>
To: Sergei Shtepa <sergei.shtepa@veeam.com>
Cc: Jens Axboe <axboe@kernel.dk>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christoph Hellwig <hch@infradead.org>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
linux-xfs@vger.kernel.org,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
rjw@rjwysocki.net, len.brown@intel.com,
Pavel Machek <pavel@ucw.cz>,
Andrew Morton <akpm@linux-foundation.org>,
johannes.thumshirn@wdc.com, Ming Lei <ming.lei@redhat.com>,
Jan Kara <jack@suse.cz>, Tejun Heo <tj@kernel.org>,
gustavo@embeddedor.com, Bart Van Assche <bvanassche@acm.org>,
osandov@fb.com, koct9i@gmail.com,
Damien Le Moal <damien.lemoal@wdc.com>,
steve@sk2.org, linux-block <linux-block@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-pm@vger.kernel.org, linux-mm@kvack.org,
device-mapper development <dm-devel@redhat.com>
Subject: Re: [PATCH 0/2] block layer filter and block device snapshot module
Date: Thu, 22 Oct 2020 14:35:02 -0400 [thread overview]
Message-ID: <CAMM=eLfTf2f2Me7f5tpL5DEGgKsqaFaAS0qTDVpLAYrwR5Jf5g@mail.gmail.com> (raw)
In-Reply-To: <1603271049-20681-1-git-send-email-sergei.shtepa@veeam.com>
On Wed, Oct 21, 2020 at 5:04 AM Sergei Shtepa <sergei.shtepa@veeam.com> wrote:
>
> Hello everyone! Requesting for your comments and suggestions.
>
> # blk-filter
>
> Block layer filter allows to intercept BIO requests to a block device.
>
> Interception is performed at the very beginning of the BIO request
> processing, and therefore does not affect the operation of the request
> processing queue. This also makes it possible to intercept requests from
> a specific block device, rather than from the entire disk.
>
> The logic of the submit_bio function has been changed - since the
> function execution results are not processed anywhere (except for swap
> and direct-io) the function won't return a value anymore.
Your desire to switch to a void return comes exactly when I've noticed
we need it.
->submit_bio's blk_qc_t return is the cookie assigned by blk-mq. Up
to this point we haven't actually used it for bio-based devices but it
seems clear we'll soon need for bio-based IO polling support.
Just today, I've been auditing drivers/md/dm.c with an eye toward
properly handling the blk_qc_t return (or lack thereof) from various
DM methods.
It could easily be that __submit_bio_noacct and __submit_bio_noacct_mq
will be updated to do something meaningful with the returned cookie
(or that DM will) to facilitate proper IO polling.
Mike
prev parent reply other threads:[~2020-10-22 18:35 UTC|newest]
Thread overview: 32+ 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 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
2020-10-23 9:13 ` hch
2020-10-23 10:31 ` Hannes Reinecke
2020-10-23 11:04 ` Sergei Shtepa
2020-10-23 11:12 ` [dm-devel] " hch
2020-10-22 18:35 ` Mike Snitzer [this message]
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