block: Deprecate bdrv_set_read_only() and users
bdrv_set_read_only() is used by some block drivers to override the
read-only option given by the user. This is not how read-only images
generally work in QEMU: Instead of second guessing what the user really
meant (which currently includes making an image read-only even if the
user didn't only use the default, but explicitly said read-only=off), we
should error out if we can't provide what the user requested.
This adds deprecation warnings to all callers of bdrv_set_read_only() so
that the behaviour can be corrected after the usual deprecation period.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block/vvfat.c b/block/vvfat.c
index a0f2335..0841cc4 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1259,7 +1259,11 @@
"Unable to set VVFAT to 'rw' when drive is read-only");
goto fail;
}
- } else {
+ } else if (!bdrv_is_read_only(bs)) {
+ error_report("Opening non-rw vvfat images without an explicit "
+ "read-only=on option is deprecated. Future versions "
+ "will refuse to open the image instead of "
+ "automatically marking the image read-only.");
/* read only is the default for safety */
ret = bdrv_set_read_only(bs, true, &local_err);
if (ret < 0) {
