block: Don't check permissions for copy on read

The assertion is currently failing. We can't require callers to have
write permissions when all they are doing is a read, so comment it out.
Add a FIXME comment in the code so that the check is re-enabled when
copy on read is refactored into its own filter driver.

Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
This commit is contained in:
Kevin Wolf 2017-04-07 12:29:05 +02:00
parent 89aa0465b9
commit 1bf03e66fd

View File

@ -945,7 +945,14 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
size_t skip_bytes;
int ret;
assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE));
/* FIXME We cannot require callers to have write permissions when all they
* are doing is a read request. If we did things right, write permissions
* would be obtained anyway, but internally by the copy-on-read code. As
* long as it is implemented here rather than in a separat filter driver,
* the copy-on-read code doesn't have its own BdrvChild, however, for which
* it could request permissions. Therefore we have to bypass the permission
* system for the moment. */
// assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE));
/* Cover entire cluster so no additional backing file I/O is required when
* allocating cluster in the image file.