block: Create bdrv_backing_flags()

Instead of manipulation flags inline, move the derivation of the flags
of a backing file into a new function next to the existing functions
that derive flags for bs->file and for the block driver open function.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Kevin Wolf 2014-04-25 13:27:34 +02:00
parent 0b50cc8853
commit 317fc44ef2
1 changed files with 17 additions and 6 deletions

23
block.c
View File

@ -798,6 +798,21 @@ static int bdrv_inherited_flags(int flags)
return flags;
}
/*
* Returns the flags that bs->backing_hd should get, based on the given flags
* for the parent BDS
*/
static int bdrv_backing_flags(int flags)
{
/* backing files always opened read-only */
flags &= ~(BDRV_O_RDWR | BDRV_O_COPY_ON_READ);
/* snapshot=on is handled on the top layer */
flags &= ~BDRV_O_SNAPSHOT;
return flags;
}
static int bdrv_open_flags(BlockDriverState *bs, int flags)
{
int open_flags = flags | BDRV_O_CACHE_WB;
@ -1093,7 +1108,7 @@ fail:
int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
{
char *backing_filename = g_malloc0(PATH_MAX);
int back_flags, ret = 0;
int ret = 0;
BlockDriver *back_drv = NULL;
Error *local_err = NULL;
@ -1121,14 +1136,10 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
back_drv = bdrv_find_format(bs->backing_format);
}
/* backing files always opened read-only */
back_flags = bs->open_flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT |
BDRV_O_COPY_ON_READ);
assert(bs->backing_hd == NULL);
ret = bdrv_open(&bs->backing_hd,
*backing_filename ? backing_filename : NULL, NULL, options,
back_flags, back_drv, &local_err);
bdrv_backing_flags(bs->open_flags), back_drv, &local_err);
if (ret < 0) {
bs->backing_hd = NULL;
bs->open_flags |= BDRV_O_NO_BACKING;