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 <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Christoph Hellwig 2011-01-24 13:32:33 +01:00 committed by Kevin Wolf
parent 2be22ca5a8
commit 6d4a2b3a47
4 changed files with 78 additions and 0 deletions

View file

@ -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",