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: Christoph Hellwig <[email protected]>
Signed-off-by: Kevin Wolf <[email protected]>
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 1cea572..8df4adf 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -53,6 +53,25 @@
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",
.params = "[-f] device",
