From: Stefan Hajnoczi <stefanha@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
eblake@redhat.com, Alasdair Kergon <agk@redhat.com>,
Mikulas Patocka <mpatocka@redhat.com>,
dm-devel@lists.linux.dev, David Teigland <teigland@redhat.com>,
Mike Snitzer <snitzer@kernel.org>, Jens Axboe <axboe@kernel.dk>,
Joe Thornber <ejt@redhat.com>
Subject: Re: [RFC 0/9] block: add llseek(SEEK_HOLE/SEEK_DATA) support
Date: Tue, 2 Apr 2024 09:04:46 -0400 [thread overview]
Message-ID: <20240402130446.GA2496428@fedora> (raw)
In-Reply-To: <20240402122617.GA30720@lst.de>
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On Tue, Apr 02, 2024 at 02:26:17PM +0200, Christoph Hellwig wrote:
> On Thu, Mar 28, 2024 at 04:39:01PM -0400, Stefan Hajnoczi wrote:
> > In the block device world there are similar concepts to holes:
> > - SCSI has Logical Block Provisioning where the "mapped" state would be
> > considered data and other states would be considered holes.
>
> But for SCSI (and ATA and NVMe) unmapped/delallocated/etc blocks do
> not have to return zeroes. They could also return some other
> initialization pattern pattern. So they are (unfortunately) not a 1:1
> mapping to holes in sparse files.
Hi Christoph,
There is a 1:1 mapping when when the Logical Block Provisioning Read
Zeroes (LBPRZ) field is set to xx1b in the Logical Block Provisioning
VPD page.
Otherwise SEEK_HOLE/SEEK_DATA has to treat the device as filled with
data because it doesn't know where the holes are.
Stefan
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next prev parent reply other threads:[~2024-04-02 13:04 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-28 20:39 [RFC 0/9] block: add llseek(SEEK_HOLE/SEEK_DATA) support Stefan Hajnoczi
2024-03-28 20:39 ` [RFC 1/9] " Stefan Hajnoczi
2024-03-28 23:50 ` Eric Blake
2024-03-28 20:39 ` [RFC 2/9] loop: " Stefan Hajnoczi
2024-03-29 0:00 ` Eric Blake
2024-03-29 12:54 ` Stefan Hajnoczi
2024-03-28 20:39 ` [RFC 3/9] selftests: block_seek_hole: add loop block driver tests Stefan Hajnoczi
2024-03-29 0:11 ` Eric Blake
2024-04-03 13:50 ` Stefan Hajnoczi
2024-03-29 12:38 ` Eric Blake
2024-04-03 13:51 ` Stefan Hajnoczi
2024-03-28 20:39 ` [RFC 4/9] dm: add llseek(SEEK_HOLE/SEEK_DATA) support Stefan Hajnoczi
2024-03-29 0:38 ` Eric Blake
2024-04-03 14:11 ` Stefan Hajnoczi
2024-04-03 17:02 ` Eric Blake
2024-04-03 17:58 ` Stefan Hajnoczi
2024-04-03 19:28 ` Eric Blake
2024-03-28 20:39 ` [RFC 5/9] selftests: block_seek_hole: add dm-zero test Stefan Hajnoczi
2024-03-28 22:19 ` Eric Blake
2024-03-28 22:32 ` Stefan Hajnoczi
2024-03-28 20:39 ` [RFC 6/9] dm-linear: add llseek(SEEK_HOLE/SEEK_DATA) support Stefan Hajnoczi
2024-03-29 0:54 ` Eric Blake
2024-04-03 14:22 ` Stefan Hajnoczi
2024-03-31 7:35 ` kernel test robot
2024-04-03 14:14 ` Stefan Hajnoczi
2024-03-28 20:39 ` [RFC 7/9] selftests: block_seek_hole: add dm-linear test Stefan Hajnoczi
2024-03-29 0:59 ` Eric Blake
2024-04-03 14:23 ` Stefan Hajnoczi
2024-03-28 20:39 ` [RFC 8/9] dm thin: add llseek(SEEK_HOLE/SEEK_DATA) support Stefan Hajnoczi
2024-03-29 1:31 ` Eric Blake
2024-04-03 15:03 ` Stefan Hajnoczi
2024-03-28 20:39 ` [RFC 9/9] selftests: block_seek_hole: add dm-thin test Stefan Hajnoczi
2024-03-28 22:16 ` [RFC 0/9] block: add llseek(SEEK_HOLE/SEEK_DATA) support Eric Blake
2024-03-28 22:29 ` Eric Blake
2024-03-28 23:09 ` Stefan Hajnoczi
2024-04-02 12:26 ` Christoph Hellwig
2024-04-02 13:04 ` Stefan Hajnoczi [this message]
2024-04-05 7:02 ` Christoph Hellwig
2024-04-02 13:31 ` Eric Blake
2024-04-05 7:02 ` Christoph Hellwig
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