Commit 6d4a2b3a authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Kevin Wolf
Browse files

block: add block_resize monitor command



Add a monitor command that allows resizing of block devices while
qemu is running.  It uses the existing bdrv_truncate method already
used by qemu-img to do it's work.  Compared to qemu-img the size
parsing is very simplicistic, but I think having a properly numering
object is more useful for non-humand monitor users than having
the units and relative resize parsing.

For SCSI devices the new size can be updated in Linux guests by
doing the following shell command:

	echo > /sys/class/scsi_device/0:0:0:0/device/rescan

For ATA devices I don't know of a way to update the block device
size in Linux system, and for virtio-blk the next two patches
will provide an automatic update of the size when this command
is issued on the host.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 2be22ca5
......@@ -705,3 +705,33 @@ int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
return 0;
}
/*
* XXX: replace the QERR_UNDEFINED_ERROR errors with real values once the
* existing QERR_ macro mess is cleaned up. A good example for better
* error reports can be found in the qemu-img resize code.
*/
int do_block_resize(Monitor *mon, const QDict *qdict, QObject **ret_data)
{
const char *device = qdict_get_str(qdict, "device");
int64_t size = qdict_get_int(qdict, "size");
BlockDriverState *bs;
bs = bdrv_find(device);
if (!bs) {
qerror_report(QERR_DEVICE_NOT_FOUND, device);
return -1;
}
if (size < 0) {
qerror_report(QERR_UNDEFINED_ERROR);
return -1;
}
if (bdrv_truncate(bs, size)) {
qerror_report(QERR_UNDEFINED_ERROR);
return -1;
}
return 0;
}
......@@ -53,5 +53,6 @@ int do_change_block(Monitor *mon, const char *device,
const char *filename, const char *fmt);
int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data);
int do_snapshot_blkdev(Monitor *mon, const QDict *qdict, QObject **ret_data);
int do_block_resize(Monitor *mon, const QDict *qdict, QObject **ret_data);
#endif
......@@ -52,6 +52,25 @@ STEXI
Quit the emulator.
ETEXI
{
.name = "block_resize",
.args_type = "device:B,size:o",
.params = "device size",
.help = "resize a block image",
.user_print = monitor_user_noop,
.mhandler.cmd_new = do_block_resize,
},
STEXI
@item block_resize
@findex block_resize
Resize a block image while a guest is running. Usually requires guest
action to see the updated size. Resize to a lower size is supported,
but should be used with extreme caution. Note that this command only
resizes image files, it can not resize block devices like LVM volumes.
ETEXI
{
.name = "eject",
.args_type = "force:-f,device:B",
......
......@@ -601,6 +601,34 @@ Example:
-> { "execute": "netdev_del", "arguments": { "id": "netdev1" } }
<- { "return": {} }
EQMP
{
.name = "block_resize",
.args_type = "device:B,size:o",
.params = "device size",
.help = "resize a block image",
.user_print = monitor_user_noop,
.mhandler.cmd_new = do_block_resize,
},
SQMP
block_resize
------------
Resize a block image while a guest is running.
Arguments:
- "device": the device's ID, must be unique (json-string)
- "size": new size
Example:
-> { "execute": "block_resize", "arguments": { "device": "scratch", "size": 1073741824 } }
<- { "return": {} }
EQMP
{
......
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