From mboxrd@z Thu Jan  1 00:00:00 1970
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Subject: Re: [PATCH] block: get rid of blk_integrity_revalidate()
To: Ilya Dryomov <idryomov@gmail.com>, "Martin K. Petersen"
 <martin.petersen@oracle.com>
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From: Jens Axboe <axboe@fb.com>
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Date: Fri, 21 Apr 2017 14:18:08 -0600
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Cc: Mike Snitzer <snitzer@redhat.com>, ceph-devel@vger.kernel.org,
 linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
 dm-devel@redhat.com, Dan Williams <dan.j.williams@intel.com>,
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On 04/18/2017 10:43 AM, Ilya Dryomov wrote:
> Commit 25520d55cdb6 ("block: Inline blk_integrity in struct gendisk")
> introduced blk_integrity_revalidate(), which seems to assume ownership
> of the stable pages flag and unilaterally clears it if no blk_integrity
> profile is registered:
> 
>     if (bi->profile)
>             disk->queue->backing_dev_info->capabilities |=
>                     BDI_CAP_STABLE_WRITES;
>     else
>             disk->queue->backing_dev_info->capabilities &=
>                     ~BDI_CAP_STABLE_WRITES;
> 
> It's called from revalidate_disk() and rescan_partitions(), making it
> impossible to enable stable pages for drivers that support partitions
> and don't use blk_integrity: while the call in revalidate_disk() can be
> trivially worked around (see zram, which doesn't support partitions and
> hence gets away with zram_revalidate_disk()), rescan_partitions() can
> be triggered from userspace at any time.  This breaks rbd, where the
> ceph messenger is responsible for generating/verifying CRCs.
> 
> Since blk_integrity_{un,}register() "must" be used for (un)registering
> the integrity profile with the block layer, move BDI_CAP_STABLE_WRITES
> setting there.  This way drivers that call blk_integrity_register() and
> use integrity infrastructure won't interfere with drivers that don't
> but still want stable pages.

Applied, thanks.

-- 
Jens Axboe


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