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From: Kevin Wolf <kwolf@redhat.com>
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Date: Mon, 5 Nov 2018 17:37:30 +0100
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Subject: [Qemu-devel] [PULL 22/36] block: Require auto-read-only for
existing fallbacks
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Some block drivers have traditionally changed their node to read-only
mode without asking the user. This behaviour has been marked deprecated
since 2.11, expecting users to provide an explicit read-only=3Don option.
Now that we have auto-read-only=3Don, enable these drivers to make use of
the option.
This is the only use of bdrv_set_read_only(), so we can make it a bit
more specific and turn it into a bdrv_apply_auto_read_only() that is
more convenient for drivers to use.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
include/block/block.h | 3 ++-
block.c | 42 +++++++++++++++++++++++++++---------------
block/bochs.c | 17 ++++++-----------
block/cloop.c | 16 +++++-----------
block/dmg.c | 16 +++++-----------
block/rbd.c | 15 ++++-----------
block/vvfat.c | 10 ++--------
7 files changed, 51 insertions(+), 68 deletions(-)
diff --git a/include/block/block.h b/include/block/block.h
index 580b3716c3..7f5453b45b 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -438,7 +438,8 @@ int bdrv_is_allocated_above(BlockDriverState *top, Bloc=
kDriverState *base,
bool bdrv_is_read_only(BlockDriverState *bs);
int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
bool ignore_allow_rdw, Error **errp);
-int bdrv_set_read_only(BlockDriverState *bs, bool read_only, Error **errp);
+int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
+ Error **errp);
bool bdrv_is_writable(BlockDriverState *bs);
bool bdrv_is_sg(BlockDriverState *bs);
bool bdrv_is_inserted(BlockDriverState *bs);
diff --git a/block.c b/block.c
index 96090c3b9a..fd67e14dfa 100644
--- a/block.c
+++ b/block.c
@@ -266,29 +266,41 @@ int bdrv_can_set_read_only(BlockDriverState *bs, bool=
read_only,
return 0;
}
=20
-/* 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)
+/*
+ * Called by a driver that can only provide a read-only image.
+ *
+ * Returns 0 if the node is already read-only or it could switch the node =
to
+ * read-only because BDRV_O_AUTO_RDONLY is set.
+ *
+ * Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not=
set
+ * or bdrv_can_set_read_only() forbids making the node read-only. If @errm=
sg
+ * is not NULL, it is used as the error message for the Error object.
+ */
+int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
+ Error **errp)
{
int ret =3D 0;
=20
- ret =3D bdrv_can_set_read_only(bs, read_only, false, errp);
- if (ret < 0) {
- return ret;
+ if (!(bs->open_flags & BDRV_O_RDWR)) {
+ return 0;
+ }
+ if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) {
+ goto fail;
}
=20
- bs->read_only =3D read_only;
-
- if (read_only) {
- bs->open_flags &=3D ~BDRV_O_RDWR;
- } else {
- bs->open_flags |=3D BDRV_O_RDWR;
+ ret =3D bdrv_can_set_read_only(bs, true, false, NULL);
+ if (ret < 0) {
+ goto fail;
}
=20
+ bs->read_only =3D true;
+ bs->open_flags &=3D ~BDRV_O_RDWR;
+
return 0;
+
+fail:
+ error_setg(errp, "%s", errmsg ?: "Image is read-only");
+ return -EACCES;
}
=20
void bdrv_get_full_backing_filename_from_filename(const char *backed,
diff --git a/block/bochs.c b/block/bochs.c
index 50c630047b..22e7d44211 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -105,23 +105,18 @@ static int bochs_open(BlockDriverState *bs, QDict *op=
tions, int flags,
struct bochs_header bochs;
int ret;
=20
+ /* No write support yet */
+ ret =3D bdrv_apply_auto_read_only(bs, NULL, errp);
+ if (ret < 0) {
+ return ret;
+ }
+
bs->file =3D bdrv_open_child(NULL, options, "file", bs, &child_file,
false, errp);
if (!bs->file) {
return -EINVAL;
}
=20
- if (!bdrv_is_read_only(bs)) {
- error_report("Opening bochs images without an explicit read-only=
=3Don "
- "option is deprecated. Future versions will refuse to=
"
- "open the image instead of automatically marking the "
- "image read-only.");
- ret =3D bdrv_set_read_only(bs, true, errp); /* no write support ye=
t */
- if (ret < 0) {
- return ret;
- }
- }
-
ret =3D bdrv_pread(bs->file, 0, &bochs, sizeof(bochs));
if (ret < 0) {
return ret;
diff --git a/block/cloop.c b/block/cloop.c
index 2be68987bd..df2b85f723 100644
--- a/block/cloop.c
+++ b/block/cloop.c
@@ -67,23 +67,17 @@ static int cloop_open(BlockDriverState *bs, QDict *opti=
ons, int flags,
uint32_t offsets_size, max_compressed_block_size =3D 1, i;
int ret;
=20
+ ret =3D bdrv_apply_auto_read_only(bs, NULL, errp);
+ if (ret < 0) {
+ return ret;
+ }
+
bs->file =3D bdrv_open_child(NULL, options, "file", bs, &child_file,
false, errp);
if (!bs->file) {
return -EINVAL;
}
=20
- if (!bdrv_is_read_only(bs)) {
- error_report("Opening cloop images without an explicit read-only=
=3Don "
- "option is deprecated. Future versions will refuse to=
"
- "open the image instead of automatically marking the "
- "image read-only.");
- ret =3D bdrv_set_read_only(bs, true, errp);
- if (ret < 0) {
- return ret;
- }
- }
-
/* read header */
ret =3D bdrv_pread(bs->file, 128, &s->block_size, 4);
if (ret < 0) {
diff --git a/block/dmg.c b/block/dmg.c
index c9b3c519c4..1d9283ba2f 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -413,23 +413,17 @@ static int dmg_open(BlockDriverState *bs, QDict *opti=
ons, int flags,
int64_t offset;
int ret;
=20
+ ret =3D bdrv_apply_auto_read_only(bs, NULL, errp);
+ if (ret < 0) {
+ return ret;
+ }
+
bs->file =3D bdrv_open_child(NULL, options, "file", bs, &child_file,
false, errp);
if (!bs->file) {
return -EINVAL;
}
=20
- if (!bdrv_is_read_only(bs)) {
- error_report("Opening dmg images without an explicit read-only=3Do=
n "
- "option is deprecated. Future versions will refuse to=
"
- "open the image instead of automatically marking the "
- "image read-only.");
- ret =3D bdrv_set_read_only(bs, true, errp);
- if (ret < 0) {
- return ret;
- }
- }
-
block_module_load_one("dmg-bz2");
=20
s->n_chunks =3D 0;
diff --git a/block/rbd.c b/block/rbd.c
index 1e9819a50f..8a1a9f4b6e 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -780,17 +780,10 @@ 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 !=3D NULL) {
- if (!bdrv_is_read_only(bs)) {
- error_report("Opening rbd snapshots without an explicit "
- "read-only=3Don option is deprecated. Future vers=
ions "
- "will refuse to open the image instead of "
- "automatically marking the image read-only.");
- r =3D bdrv_set_read_only(bs, true, &local_err);
- if (r < 0) {
- rbd_close(s->image);
- error_propagate(errp, local_err);
- goto failed_open;
- }
+ r =3D bdrv_apply_auto_read_only(bs, "rbd snapshots are read-only",=
errp);
+ if (r < 0) {
+ rbd_close(s->image);
+ goto failed_open;
}
}
=20
diff --git a/block/vvfat.c b/block/vvfat.c
index 98ba5e2bac..e4df255d58 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1262,15 +1262,9 @@ static int vvfat_open(BlockDriverState *bs, QDict *o=
ptions, int flags,
"Unable to set VVFAT to 'rw' when drive is read-onl=
y");
goto fail;
}
- } else if (!bdrv_is_read_only(bs)) {
- error_report("Opening non-rw vvfat images without an explicit "
- "read-only=3Don 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 =3D bdrv_set_read_only(bs, true, &local_err);
+ } else {
+ ret =3D bdrv_apply_auto_read_only(bs, NULL, errp);
if (ret < 0) {
- error_propagate(errp, local_err);
goto fail;
}
}
--=20
2.19.1