Commit 418661e0 authored Jan 25, 2017 by Jeff Cody Committed by Max Reitz Feb 12, 2017

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>

parent 4545d4f4

block.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -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 */