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Blame SOURCES/kvm-block-file-posix-do-not-fail-on-unlock-bytes.patch

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From 87240c5fcfb3e3ba68c5c87d2175f2dd98921a7e Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Wed, 3 Apr 2019 17:13:15 +0100
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Subject: [PATCH 08/11] block/file-posix: do not fail on unlock bytes
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RH-Author: Max Reitz <mreitz@redhat.com>
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Message-id: <20190403171315.20841-9-mreitz@redhat.com>
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Patchwork-id: 85406
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O-Subject: [RHEL-8.1 qemu-kvm PATCH 8/8] block/file-posix: do not fail on unlock bytes
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Bugzilla: 1694148
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
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From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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bdrv_replace_child() calls bdrv_check_perm() with error_abort on
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loosening permissions. However file-locking operations may fail even
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in this case, for example on NFS. And this leads to Qemu crash.
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Let's avoid such errors. Note, that we ignore such things anyway on
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permission update commit and abort.
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Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 696aaaed579ac5bf5fa336216909b46d3d8f07a8)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 block/file-posix.c | 12 ++++++++++++
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 1 file changed, 12 insertions(+)
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diff --git a/block/file-posix.c b/block/file-posix.c
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index deecf58..5fb5a9a 100644
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--- a/block/file-posix.c
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+++ b/block/file-posix.c
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@@ -800,6 +800,18 @@ static int raw_handle_perm_lock(BlockDriverState *bs,
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     switch (op) {
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     case RAW_PL_PREPARE:
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+        if ((s->perm | new_perm) == s->perm &&
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+            (s->shared_perm & new_shared) == s->shared_perm)
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+        {
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+            /*
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+             * We are going to unlock bytes, it should not fail. If it fail due
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+             * to some fs-dependent permission-unrelated reasons (which occurs
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+             * sometimes on NFS and leads to abort in bdrv_replace_child) we
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+             * can't prevent such errors by any check here. And we ignore them
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+             * anyway in ABORT and COMMIT.
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+             */
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+            return 0;
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+        }
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         ret = raw_apply_lock_bytes(s, s->fd, s->perm | new_perm,
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                                    ~s->shared_perm | ~new_shared,
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                                    false, errp);
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-- 
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1.8.3.1
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