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[Qemu-devel] [PATCH 1/3] block: add block_resize monitor command
From: |
Christoph Hellwig |
Subject: |
[Qemu-devel] [PATCH 1/3] block: add block_resize monitor command |
Date: |
Mon, 24 Jan 2011 13:32:33 +0100 |
User-agent: |
Mutt/1.3.28i |
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 <address@hidden>
Index: qemu/hmp-commands.hx
===================================================================
--- qemu.orig/hmp-commands.hx 2011-01-24 11:55:36.744254374 +0100
+++ qemu/hmp-commands.hx 2011-01-24 11:56:23.619254094 +0100
@@ -53,6 +53,25 @@ 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
address@hidden block_resize
address@hidden 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",
Index: qemu/blockdev.c
===================================================================
--- qemu.orig/blockdev.c 2011-01-24 11:56:20.903004129 +0100
+++ qemu/blockdev.c 2011-01-24 11:56:38.391254165 +0100
@@ -705,3 +705,33 @@ int do_drive_del(Monitor *mon, const QDi
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;
+}
Index: qemu/blockdev.h
===================================================================
--- qemu.orig/blockdev.h 2011-01-24 11:55:36.764254165 +0100
+++ qemu/blockdev.h 2011-01-24 11:56:23.627253465 +0100
@@ -53,5 +53,6 @@ int do_change_block(Monitor *mon, const
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
Index: qemu/qmp-commands.hx
===================================================================
--- qemu.orig/qmp-commands.hx 2011-01-24 11:55:36.771253955 +0100
+++ qemu/qmp-commands.hx 2011-01-24 11:56:23.632253884 +0100
@@ -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
{
[Qemu-devel] [PATCH 2/3] block: tell drivers about an image resize, Christoph Hellwig, 2011/01/24
[Qemu-devel] [PATCH 3/3] virtio-blk: tell the guest about size changes, Christoph Hellwig, 2011/01/24
Re: [Qemu-devel] [PATCH 0/3 v3] allow online resizing of block devices, Kevin Wolf, 2011/01/26
Re: [Qemu-devel] [PATCH 0/3 v3] allow online resizing of block devices, Stefan Hajnoczi, 2011/01/26