From 168f27ca545f530ac694ed596bdafc8fa3c26860 Mon Sep 17 00:00:00 2001

From: Kevin Wolf <kwolf@redhat.com>

Date: Fri, 15 Mar 2019 18:10:00 +0100

Subject: [PATCH 004/163] block: Always abort reopen after prepare succeeded

RH-Author: Kevin Wolf <kwolf@redhat.com>

Message-id: <20190315181010.14964-5-kwolf@redhat.com>

Patchwork-id: 84881

O-Subject: [RHEL-7.7 qemu-kvm-rhev PATCH 04/14] block: Always abort reopen after prepare succeeded

Bugzilla: 1685989

RH-Acked-by: John Snow <jsnow@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

From: Max Reitz <mreitz@redhat.com>

bdrv_reopen_multiple() does not invoke bdrv_reopen_abort() for the

element of the reopen queue for which bdrv_reopen_prepare() failed,

because it assumes that the prepare function will have rolled back all

changes already.

However, bdrv_reopen_prepare() does not do this in every case: It may

notice an error after BlockDriver.bdrv_reopen_prepare() succeeded, and

it will not invoke BlockDriver.bdrv_reopen_abort() then; and neither

will bdrv_reopen_multiple(), as explained above.

This is wrong because we must always call .bdrv_reopen_commit() or

.bdrv_reopen_abort() after .bdrv_reopen_prepare() has succeeded.

Otherwise, the block driver has no chance to undo what it has done in

its implementation of .bdrv_reopen_prepare().

To fix this, bdrv_reopen_prepare() has to call .bdrv_reopen_abort() if

it wants to return an error after .bdrv_reopen_prepare() has succeeded.

Signed-off-by: Max Reitz <mreitz@redhat.com>

Reviewed-by: Alberto Garcia <berto@igalia.com>

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

(cherry picked from commit 9ad08c44566bf4466c6263c71d43e9f7a354d4ba)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 block.c | 12 ++++++++++++

 1 file changed, 12 insertions(+)

diff --git a/block.c b/block.c

index c3148cc..2f1b4d1 100644

--- a/block.c

+++ b/block.c

@@ -3191,6 +3191,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,

     QemuOpts *opts;

     const char *value;

     bool read_only;

+    bool drv_prepared = false;

     assert(reopen_state != NULL);

     assert(reopen_state->bs->drv != NULL);

@@ -3260,6 +3261,8 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,

         goto error;

     }

+    drv_prepared = true;

+

     /* Options that are not handled are only okay if they are unchanged

      * compared to the old state. It is expected that some options are only

      * used for the initial open, but not reopen (e.g. filename) */

@@ -3303,6 +3306,15 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,

     ret = 0;

 error:

+    if (ret < 0 && drv_prepared) {

+        /* drv->bdrv_reopen_prepare() has succeeded, so we need to

+         * call drv->bdrv_reopen_abort() before signaling an error

+         * (bdrv_reopen_multiple() will not call bdrv_reopen_abort()

+         * when the respective bdrv_reopen_prepare() has failed) */

+        if (drv->bdrv_reopen_abort) {

+            drv->bdrv_reopen_abort(reopen_state);

+        }

+    }

     qemu_opts_del(opts);

     return ret;

 }

-- 

1.8.3.1