[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 1/3] block: add block_resize monitor command
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH 1/3] block: add block_resize monitor command |
Date: |
Tue, 25 Jan 2011 13:01:04 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.15) Gecko/20101027 Fedora/3.0.10-1.fc12 Thunderbird/3.0.10 |
Am 24.01.2011 18:44, schrieb Marcelo Tosatti:
> On Mon, Jan 24, 2011 at 01:32:33PM +0100, Christoph Hellwig wrote:
>> 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;
>> + }
>
> Can't resize if block migration is in progress. Don't see a problem
> with simply disallowing resize in that case.
Then we should add a check to bdrv_truncate.
Kevin
[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