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block: Always abort reopen after prepare succeeded

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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>
This commit is contained in:
Max Reitz 2018-11-16 17:45:24 +01:00 committed by Kevin Wolf
parent 3b94c343f9
commit 9ad08c4456
1 changed files with 12 additions and 0 deletions
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12
block.c
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@ -3201,6 +3201,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
QDict *orig_reopen_opts;
char *discard = NULL;
bool read_only;
bool drv_prepared = false;
assert(reopen_state != NULL);
assert(reopen_state->bs->drv != NULL);
@ -3285,6 +3286,8 @@ 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) */
@ -3350,6 +3353,15 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
reopen_state->options = qobject_ref(orig_reopen_opts);
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);
qobject_unref(orig_reopen_opts);
g_free(discard);