block: check full backing filename when searching protocol filenames

In bdrv_find_backing_image(), if we are searching an image for a backing
file that contains a protocol, we currently only compare unmodified
paths.

However, some management software will change the backing filename to be
a relative filename in a path.  QEMU is able to handle this fine,
because internally it will use path_combine to put together the full
protocol URI.

However, this can lead to an inability to match an image during a QAPI
command that needs to use bdrv_find_backing_image() to find the image,
when it is searched by the full URI.

When searching for a protocol filename, if the straight comparison
fails, this patch will also compare against the full backing filename to
see if that is a match.

Signed-off-by: Jeff Cody <jcody@redhat.com>
Message-id: c2d025adca8a2b665189e6f4cf080f44126d0b6b.1485392617.git.jcody@redhat.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Jeff Cody 2017-01-25 20:08:20 -05:00 committed by Max Reitz
parent 4545d4f4af
commit 418661e032

13
block.c
View File

@ -3145,6 +3145,7 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
int is_protocol = 0;
BlockDriverState *curr_bs = NULL;
BlockDriverState *retval = NULL;
Error *local_error = NULL;
if (!bs || !bs->drv || !backing_file) {
return NULL;
@ -3165,6 +3166,18 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
retval = curr_bs->backing->bs;
break;
}
/* Also check against the full backing filename for the image */
bdrv_get_full_backing_filename(curr_bs, backing_file_full, PATH_MAX,
&local_error);
if (local_error == NULL) {
if (strcmp(backing_file, backing_file_full) == 0) {
retval = curr_bs->backing->bs;
break;
}
} else {
error_free(local_error);
local_error = NULL;
}
} else {
/* If not an absolute filename path, make it relative to the current
* image's filename path */