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 <kw...@redhat.com>
---
block.c | 5 +++++
block/bochs.c | 13 ++++++++++---
block/cloop.c | 13 ++++++++++---
block/dmg.c | 12 +++++++++---
block/rbd.c | 14 ++++++++++----
block/vvfat.c | 6 +++++-
6 files changed, 49 insertions(+), 14 deletions(-)
diff --git a/block.c b/block.c
index f6415547fe..0ed0c27140 100644
--- a/block.c
+++ b/block.c
@@ -261,6 +261,11 @@ int bdrv_can_set_read_only(BlockDriverState *bs, bool
read_only,
return 0;
}
+/* TODO Remove (deprecated since 2.11)
+ * Block drivers are not supposed to automatically change bs->read_only.
+ * Instead, they should just check whether they can provide what the user
+ * explicitly requested and error out if read-write is requested, but they can
+ * only provide read-only access. */
int bdrv_set_read_only(BlockDriverState *bs, bool read_only, Error **errp)
{
int ret = 0;
diff --git a/block/bochs.c b/block/bochs.c
index a759b6eff0..50c630047b 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -28,6 +28,7 @@
#include "block/block_int.h"
#include "qemu/module.h"
#include "qemu/bswap.h"
+#include "qemu/error-report.h"
/**************************************************************/
@@ -110,9 +111,15 @@ static int bochs_open(BlockDriverState *bs, QDict
*options, int flags,
return -EINVAL;
}
- ret = bdrv_set_read_only(bs, true, errp); /* no write support yet */
- if (ret < 0) {
- return ret;
+ if (!bdrv_is_read_only(bs)) {
+ error_report("Opening bochs 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.");
+ ret = bdrv_set_read_only(bs, true, errp); /* no write support yet */
+ if (ret < 0) {
+ return ret;
+ }
}
ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs));
diff --git a/block/cloop.c b/block/cloop.c
index d6597fcf78..2be68987bd 100644
--- a/block/cloop.c
+++ b/block/cloop.c
@@ -23,6 +23,7 @@
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
+#include "qemu/error-report.h"
#include "qemu-common.h"
#include "block/block_int.h"
#include "qemu/module.h"
@@ -72,9 +73,15 @@ static int cloop_open(BlockDriverState *bs, QDict *options,
int flags,
return -EINVAL;
}
- ret = bdrv_set_read_only(bs, true, errp);
- if (ret < 0) {
- return ret;
+ if (!bdrv_is_read_only(bs)) {
+ error_report("Opening cloop 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.");
+ ret = bdrv_set_read_only(bs, true, errp);
+ if (ret < 0) {
+ return ret;
+ }
}
/* read header */
diff --git a/block/dmg.c b/block/dmg.c
index 6c0711f563..c9b3c519c4 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -419,9 +419,15 @@ static int dmg_open(BlockDriverState *bs, QDict *options,
int flags,
return -EINVAL;
}
- ret = bdrv_set_read_only(bs, true, errp);
- if (ret < 0) {
- return ret;
+ if (!bdrv_is_read_only(bs)) {
+ error_report("Opening dmg 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.");
+ ret = bdrv_set_read_only(bs, true, errp);
+ if (ret < 0) {
+ return ret;
+ }
}
block_module_load_one("dmg-bz2");
diff --git a/block/rbd.c b/block/rbd.c
index 144f350e1f..a76a5e8755 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -665,10 +665,16 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict
*options, int flags,
/* If we are using an rbd snapshot, we must be r/o, otherwise
* leave as-is */
if (s->snap != NULL) {
- r = bdrv_set_read_only(bs, true, &local_err);
- if (r < 0) {
- error_propagate(errp, local_err);
- goto failed_open;
+ if (!bdrv_is_read_only(bs)) {
+ error_report("Opening rbd snapshots 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.");
+ r = bdrv_set_read_only(bs, true, &local_err);
+ if (r < 0) {
+ error_propagate(errp, local_err);
+ goto failed_open;
+ }
}
}
diff --git a/block/vvfat.c b/block/vvfat.c
index a0f2335894..0841cc42fc 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1259,7 +1259,11 @@ static int vvfat_open(BlockDriverState *bs, QDict
*options, int flags,
"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) {
--
2.13.6
