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From: Kevin Wolf <kwolf@redhat.com>
To: qemu-block@nongnu.org
Date: Fri, 22 Dec 2017 16:18:12 +0100
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Subject: [Qemu-devel] [PULL v3 01/35] block: Formats don't need
CONSISTENT_READ with NO_IO
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Commit 1f4ad7d 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: Kevin Wolf <kwolf@redhat.com>
---
block.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/block.c b/block.c
index 1c37ce4554..db0be7ef36 100644
--- a/block.c
+++ b/block.c
@@ -1924,6 +1924,8 @@ void bdrv_format_default_perms(BlockDriverState *bs, =
BdrvChild *c,
assert(role =3D=3D &child_backing || role =3D=3D &child_file);
=20
if (!backing) {
+ int flags =3D 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,
=20
/* bs->file always needs to be consistent because of the metadata.=
We
* can never allow other users to resize or write to it. */
- perm |=3D BLK_PERM_CONSISTENT_READ;
+ if (!(flags & BDRV_O_NO_IO)) {
+ perm |=3D BLK_PERM_CONSISTENT_READ;
+ }
shared &=3D ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
} else {
/* We want consistent read from backing files if the parent needs =
it.
--=20
2.13.6