From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=54373 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PeszP-0000IV-Rw for qemu-devel@nongnu.org; Mon, 17 Jan 2011 12:35:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Pesyg-0004QL-0j for qemu-devel@nongnu.org; Mon, 17 Jan 2011 12:34:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53731) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Pesyf-0004Pw-QC for qemu-devel@nongnu.org; Mon, 17 Jan 2011 12:34:49 -0500 Message-ID: <4D347E0F.4040000@redhat.com> Date: Mon, 17 Jan 2011 18:36:15 +0100 From: Kevin Wolf MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH 1/3] block: add resize monitor command References: <20110114162044.GA19114@lst.de> <20110114162057.GA19184@lst.de> In-Reply-To: <20110114162057.GA19184@lst.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christoph Hellwig Cc: qemu-devel@nongnu.org Am 14.01.2011 17:20, schrieb Christoph Hellwig: > 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 > > Index: qemu/hmp-commands.hx > =================================================================== > --- qemu.orig/hmp-commands.hx 2011-01-14 15:11:48.527004132 +0100 > +++ qemu/hmp-commands.hx 2011-01-14 15:40:14.407006506 +0100 > @@ -53,6 +53,24 @@ Quit the emulator. > ETEXI > > { > + .name = "resize", > + .args_type = "id:s,size:l", size should be 'o' instead of 'l'. The latter may be too small on 32 bit hosts and doesn't support convenient suffixes: * 'l' target long (32 or 64 bit) * 'o' octets (aka bytes) * user mode accepts an optional T, t, G, g, M, m, K, k * suffix, which multiplies the value by 2^40 for * suffixes T and t, 2^30 for suffixes G and g, 2^20 for * M and m, 2^10 for K and k > + .params = "device size", > + .help = "resize a block image", > + .user_print = monitor_user_noop, > + .mhandler.cmd_new = do_resize, > + }, > + > +STEXI > +@item resize > +@findex resize > +Resize a block image while a guest is running. Usuaully requires guest > +action to see the updated size. Resize to a lower size is supported, > +but should be used with extreme caution. > +ETEXI > + > + > + { > .name = "eject", > .args_type = "force:-f,device:B", > .params = "[-f] device", > Index: qemu/blockdev.c > =================================================================== > --- qemu.orig/blockdev.c 2011-01-14 15:11:48.539261151 +0100 > +++ qemu/blockdev.c 2011-01-14 15:50:35.604293558 +0100 > @@ -700,3 +700,41 @@ int do_drive_del(Monitor *mon, const QDi > > return 0; > } > + > +int do_resize(Monitor *mon, const QDict *qdict, QObject **ret_data) > +{ > + const char *id = qdict_get_str(qdict, "id"); > + int64_t size = qdict_get_int(qdict, "size"); > + BlockDriverState *bs; > + > + bs = bdrv_find(id); > + if (!bs) { > + qerror_report(QERR_DEVICE_NOT_FOUND, id); > + return -1; > + } > + > + if (bdrv_get_type_hint(bs) == BDRV_TYPE_CDROM) { > + error_report("Can not resize CDROM devices\n"); > + return -1; > + } Hm, is there a real reason except that CD-ROMs are read-only? The code below seems to take read-only devices into account. Kevin