block: do not set BDS read_only if copy_on_read enabled
A few block drivers will set the BDS read_only flag from their
.bdrv_open() function. This means the bs->read_only flag could
be set after we enable copy_on_read, as the BDRV_O_COPY_ON_READ
flag check occurs prior to the call to bdrv->bdrv_open().
This adds an error return to bdrv_set_read_only(), and an error will be
return if we try to set the BDS to read_only while copy_on_read is
enabled.
This patch also changes the behavior of vvfat. Before, vvfat could
override the drive 'readonly' flag with its own, internal 'rw' flag.
For instance, this -drive parameter would result in a writable image:
"-drive format=vvfat,dir=/tmp/vvfat,rw,if=virtio,readonly=on"
This is not correct. Now, attempting to use the above -drive parameter
will result in an error (i.e., 'rw' is incompatible with 'readonly=on').
Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 0c5b4c1cc2c651471b131f21376dfd5ea24d2196.1491597120.git.jcody@redhat.com
diff --git a/block.c b/block.c
index 6f21145..67ae35a 100644
--- a/block.c
+++ b/block.c
@@ -192,9 +192,17 @@
}
}
-void bdrv_set_read_only(BlockDriverState *bs, bool read_only)
+int bdrv_set_read_only(BlockDriverState *bs, bool read_only, Error **errp)
{
+ /* Do not set read_only if copy_on_read is enabled */
+ if (bs->copy_on_read && read_only) {
+ error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled",
+ bdrv_get_device_or_node_name(bs));
+ return -EINVAL;
+ }
+
bs->read_only = read_only;
+ return 0;
}
void bdrv_get_full_backing_filename_from_filename(const char *backed,