Message ID | 20110124123233.GA16613@lst.de |
---|---|
State | New |
Headers | show |
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 <hch@lst.de> > > 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 > +@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", > 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.
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 <hch@lst.de> >> >> 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 >> +@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", >> 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
On Tue, Jan 25, 2011 at 01:01:04PM +0100, Kevin Wolf wrote: > > 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. What check exactly would that be anyway?
On Tue, Jan 25, 2011 at 07:05:37PM +0100, Christoph Hellwig wrote: > On Tue, Jan 25, 2011 at 01:01:04PM +0100, Kevin Wolf wrote: > > > 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. > > What check exactly would that be anyway? Need to add the information to BlockDriver state. drive_del is also broken, it can be fixed later. Patch looks good to me.
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 +@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", 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 {
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>