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[Qemu-devel] [PATCH 1/3] blockdev: Add read-only option to change-blockd
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH 1/3] blockdev: Add read-only option to change-blockdev |
Date: |
Thu, 20 Nov 2014 13:44:46 +0100 |
Add an option to qmp_change_blockdev() which allows changing the
read-only status of the block device to be changed.
Some drives do not have a inherently fixed read-only status; for
instance, floppy disks can be set read-only or writable independently of
the drive. Some users may find it useful to be able to therefore change
the read-only status of a block device when changing the medium.
Signed-off-by: Max Reitz <address@hidden>
---
blockdev.c | 41 ++++++++++++++++++++++++++++++++++++++---
include/sysemu/blockdev.h | 3 ++-
qapi-schema.json | 20 ++++++++++++++++++++
qmp.c | 3 ++-
4 files changed, 62 insertions(+), 5 deletions(-)
diff --git a/blockdev.c b/blockdev.c
index a52f205..4140a27 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1721,7 +1721,8 @@ static void qmp_bdrv_open_encrypted(BlockDriverState *bs,
const char *filename,
}
void qmp_change_blockdev(const char *device, const char *filename,
- const char *format, Error **errp)
+ const char *format,
+ BlockdevChangeReadOnlyMode read_only, Error **errp)
{
BlockBackend *blk;
BlockDriverState *bs;
@@ -1754,10 +1755,44 @@ void qmp_change_blockdev(const char *device, const char
*filename,
goto out;
}
- bdrv_flags = bdrv_is_read_only(bs) ? 0 : BDRV_O_RDWR;
+ switch (read_only) {
+ case BLOCKDEV_CHANGE_READ_ONLY_MODE_RETAIN:
+ bdrv_flags = bdrv_is_read_only(bs) ? 0 : BDRV_O_RDWR;
+ break;
+
+ case BLOCKDEV_CHANGE_READ_ONLY_MODE_RO:
+ bdrv_flags = 0;
+ break;
+
+ case BLOCKDEV_CHANGE_READ_ONLY_MODE_RW:
+ bdrv_flags = BDRV_O_RDWR;
+ break;
+
+ case BLOCKDEV_CHANGE_READ_ONLY_MODE_AUTO:
+ /* try RDWR first */
+ bdrv_flags = BDRV_O_RDWR;
+ break;
+
+ default:
+ abort();
+ }
+
bdrv_flags |= bdrv_is_snapshot(bs) ? BDRV_O_SNAPSHOT : 0;
- qmp_bdrv_open_encrypted(bs, filename, bdrv_flags, drv, NULL, errp);
+ qmp_bdrv_open_encrypted(bs, filename, bdrv_flags, drv, NULL, &err);
+
+ if (err) {
+ if (read_only == BLOCKDEV_CHANGE_READ_ONLY_MODE_AUTO) {
+ error_free(err);
+ err = NULL;
+
+ /* RDWR did not work, try RO now */
+ bdrv_flags &= ~BDRV_O_RDWR;
+ qmp_bdrv_open_encrypted(bs, filename, bdrv_flags, drv, NULL, errp);
+ } else {
+ error_propagate(errp, err);
+ }
+ }
out:
aio_context_release(aio_context);
diff --git a/include/sysemu/blockdev.h b/include/sysemu/blockdev.h
index 09d1e30..14b4dfb 100644
--- a/include/sysemu/blockdev.h
+++ b/include/sysemu/blockdev.h
@@ -66,7 +66,8 @@ DriveInfo *drive_new(QemuOpts *arg, BlockInterfaceType
block_default_type);
DriveInfo *add_init_drive(const char *opts);
void qmp_change_blockdev(const char *device, const char *filename,
- const char *format, Error **errp);
+ const char *format,
+ BlockdevChangeReadOnlyMode read_only, Error **errp);
void do_commit(Monitor *mon, const QDict *qdict);
int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data);
#endif
diff --git a/qapi-schema.json b/qapi-schema.json
index d0926d9..441e001 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1543,6 +1543,26 @@
{ 'command': 'change-vnc-password', 'data': {'password': 'str'} }
##
+# @BlockdevChangeReadOnlyMode:
+#
+# Specifies the new read-only mode of a block device subject to the @change
+# command.
+#
+# @retain: Retains the current read-only mode
+#
+# @ro: Makes the device read-only
+#
+# @rw: Makes the device writable
+#
+# @auto: If the file specified can be opened with write access, the block
+# device will be writable; otherwise it will be read-only
+#
+# Since: 2.3
+##
+{ 'enum': 'BlockdevChangeReadOnlyMode',
+ 'data': ['retain', 'ro', 'rw', 'auto'] }
+
+##
# @change:
#
# This command is multiple commands multiplexed together.
diff --git a/qmp.c b/qmp.c
index 0b4f131..bd63cf4 100644
--- a/qmp.c
+++ b/qmp.c
@@ -402,7 +402,8 @@ void qmp_change(const char *device, const char *target,
if (strcmp(device, "vnc") == 0) {
qmp_change_vnc(target, has_arg, arg, errp);
} else {
- qmp_change_blockdev(device, target, arg, errp);
+ qmp_change_blockdev(device, target, arg,
+ BLOCKDEV_CHANGE_READ_ONLY_MODE_RETAIN, errp);
}
}
--
1.9.3