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From a80280654277c361714ec5f3925d2d6b077eca7b Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Mon, 15 Jan 2018 11:23:37 +0100
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Subject: [PATCH 12/12] block: Formats don't need CONSISTENT_READ with NO_IO
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <20180115112337.20885-4-kwolf@redhat.com>
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Patchwork-id: 78574
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O-Subject: [RHV-7.5 qemu-kvm-rhev PATCH 3/3] block: Formats don't need CONSISTENT_READ with NO_IO
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Bugzilla: 1515604
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
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RH-Acked-by: John Snow <jsnow@redhat.com>
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Commit 1f4ad7d fixed 'qemu-img info' for raw images that are currently
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in use as a mirror target. It is not enough for image formats, though,
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as these still unconditionally request BLK_PERM_CONSISTENT_READ.
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As this permission is geared towards whether the guest-visible data is
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consistent, and has no impact on whether the metadata is sane, and
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'qemu-img info' does not read guest-visible data (except for the raw
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format), it makes sense to not require BLK_PERM_CONSISTENT_READ if there
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is not going to be any guest I/O performed, regardless of image format.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 5fbfabd313b77e1cc7038ae8c4481c4b9f8b650a)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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block.c | 6 +++++-
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1 file changed, 5 insertions(+), 1 deletion(-)
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diff --git a/block.c b/block.c
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index 90a60bc..ca8a46b 100644
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--- a/block.c
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+++ b/block.c
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@@ -1885,6 +1885,8 @@ void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c,
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assert(role == &child_backing || role == &child_file);
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if (!backing) {
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+ int flags = bdrv_reopen_get_flags(reopen_queue, bs);
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+
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/* Apart from the modifications below, the same permissions are
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* forwarded and left alone as for filters */
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bdrv_filter_default_perms(bs, c, role, reopen_queue, perm, shared,
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@@ -1897,7 +1899,9 @@ void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c,
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/* bs->file always needs to be consistent because of the metadata. We
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* can never allow other users to resize or write to it. */
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- perm |= BLK_PERM_CONSISTENT_READ;
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+ if (!(flags & BDRV_O_NO_IO)) {
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+ perm |= BLK_PERM_CONSISTENT_READ;
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+ }
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shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
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} else {
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/* We want consistent read from backing files if the parent needs it.
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--
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1.8.3.1
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