Commit 5fbfabd3 authored by Kevin Wolf's avatar Kevin Wolf
Browse files

block: Formats don't need CONSISTENT_READ with NO_IO 



Commit 1f4ad7d3 fixed 'qemu-img info' for raw images that are currently
in use as a mirror target. It is not enough for image formats, though,
as these still unconditionally request BLK_PERM_CONSISTENT_READ.

As this permission is geared towards whether the guest-visible data is
consistent, and has no impact on whether the metadata is sane, and
'qemu-img info' does not read guest-visible data (except for the raw
format), it makes sense to not require BLK_PERM_CONSISTENT_READ if there
is not going to be any guest I/O performed, regardless of image format.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 281f3274

block.c

+5 −1
Original line number Diff line number Diff line
@@ -1924,6 +1924,8 @@ void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c, 
    assert(role == &child_backing || role == &child_file);



    if (!backing) {

        int flags = bdrv_reopen_get_flags(reopen_queue, bs);



        /* Apart from the modifications below, the same permissions are

         * forwarded and left alone as for filters */

        bdrv_filter_default_perms(bs, c, role, reopen_queue, perm, shared,
@@ -1936,7 +1938,9 @@ void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c, 


        /* bs->file always needs to be consistent because of the metadata. We

         * can never allow other users to resize or write to it. */

        if (!(flags & BDRV_O_NO_IO)) {

            perm |= BLK_PERM_CONSISTENT_READ;

        }

        shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);

    } else {

        /* We want consistent read from backing files if the parent needs it.