From: Eric Blake <eblake@redhat.com>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
qemu-block@nongnu.org
Cc: fam@euphon.net, kwolf@redhat.com, ronniesahlberg@gmail.com,
codyprime@gmail.com, sw@weilnetz.de, pl@kamp.de,
qemu-devel@nongnu.org, mreitz@redhat.com, stefanha@redhat.com,
pbonzini@redhat.com, den@openvz.org
Subject: Re: [PATCH 8/8] block: drop unallocated_blocks_are_zero
Date: Wed, 6 May 2020 10:50:40 -0500 [thread overview]
Message-ID: <11bf5052-fe99-797f-3f76-5998f7376b54@redhat.com> (raw)
In-Reply-To: <20200506092513.20904-9-vsementsov@virtuozzo.com>
On 5/6/20 4:25 AM, Vladimir Sementsov-Ogievskiy wrote:
> Currently this field only set by qed and qcow2. But in fact, all
> backing-supporting formats (parallels, qcow, qcow2, qed, vmdk) share
> this semantics: on unallocated blocks, if there is no backing file they
> just memset the buffer with zeroes.
In checking the behavior of all 5 .supports_backing drivers, I noticed
that qed.c:qed_read_backing_file() does a lot of redundant work in
computing the backing file size itself, when it could just defer to the
block layer like all the other drivers do. That would be a separate patch.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
prev parent reply other threads:[~2020-05-06 15:51 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-06 9:25 [PATCH 0/8] drop unallocated_blocks_are_zero Vladimir Sementsov-Ogievskiy
2020-05-06 9:25 ` [PATCH 1/8] block/vdi: return ZERO block-status when appropriate Vladimir Sementsov-Ogievskiy
2020-05-06 13:57 ` Eric Blake
2020-05-06 14:49 ` Vladimir Sementsov-Ogievskiy
2020-05-07 7:22 ` Vladimir Sementsov-Ogievskiy
2020-05-06 9:25 ` [PATCH 2/8] block/vpc: " Vladimir Sementsov-Ogievskiy
2020-05-06 21:18 ` Eric Blake
2020-05-07 7:08 ` Vladimir Sementsov-Ogievskiy
2020-05-06 9:25 ` [PATCH 3/8] block/crypto: drop unallocated_blocks_are_zero Vladimir Sementsov-Ogievskiy
2020-05-06 21:21 ` Eric Blake
2020-05-06 9:25 ` [PATCH 4/8] block/iscsi: " Vladimir Sementsov-Ogievskiy
2020-05-06 21:25 ` Eric Blake
2020-05-06 9:25 ` [PATCH 5/8] block/file-posix: " Vladimir Sementsov-Ogievskiy
2020-05-06 21:41 ` Eric Blake
2020-05-06 9:25 ` [PATCH 6/8] block/vhdx: " Vladimir Sementsov-Ogievskiy
2020-05-06 21:43 ` Eric Blake
2020-05-06 9:25 ` [PATCH 7/8] qemu-img: convert: don't use unallocated_blocks_are_zero Vladimir Sementsov-Ogievskiy
2020-05-06 14:49 ` Eric Blake
2020-05-06 14:58 ` Vladimir Sementsov-Ogievskiy
2020-05-06 9:25 ` [PATCH 8/8] block: drop unallocated_blocks_are_zero Vladimir Sementsov-Ogievskiy
2020-05-06 15:14 ` Eric Blake
2020-05-06 15:30 ` Vladimir Sementsov-Ogievskiy
2020-05-07 7:05 ` Vladimir Sementsov-Ogievskiy
2020-05-07 8:24 ` Vladimir Sementsov-Ogievskiy
2020-05-07 8:35 ` Vladimir Sementsov-Ogievskiy
2020-05-06 15:50 ` Eric Blake [this message]
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