* [Qemu-devel] QEMU online guest disk resize wrt host block devices
@ 2011-09-01 13:27 Daniel P. Berrange
2011-09-01 14:05 ` Christoph Hellwig
2011-09-01 14:27 ` [Qemu-devel] QEMU online guest disk resize wrt host block devices Daniel P. Berrange
0 siblings, 2 replies; 10+ messages in thread
From: Daniel P. Berrange @ 2011-09-01 13:27 UTC (permalink / raw)
To: qemu-devel; +Cc: hch
We want to support online resize of guest disks in the libvirt API for
QEMU, and had intended to use the fairly recently added 'block_resize'
command:
commit db97ee6a976bacbb0d18818e951cfc41b39269a7
Author: Christoph Hellwig <hch@lst.de>
Date: Mon Jan 24 13:32:41 2011 +0100
block: tell drivers about an image resize
commit 6d4a2b3a47959f02e7f307f50396e70e8464f95e
Author: Christoph Hellwig <hch@lst.de>
Date: Mon Jan 24 13:32:33 2011 +0100
block: add block_resize monitor command
There is unfortunately a problem with the design of this monitor command
because it has tied the task of resizing the host backing file for the
virtual disk, together with the task of notifying the guest device of the
block resize. This means that we can only use 'block_resize' for disks
that are backed by image files (raw, qcow2, etc) that QEMU can actually
resize.
To be able to support online resize of virtual disks backed by host
block devices, LVM volumes, SCSI LUNs, iSCSI LUNs, etc we need to be
able to decouple these tasks. The resize of the block device needs to
be done outside QEMU, either by privileged tools on the host, or by a
remote SAN administrator, or a combo of both.
IOW, we need a way to tell QEMU to merely re-read the host file/block
size to detect an externally performed resize, and then just notify
the guest. While this would also be sufficient for raw file images,
obviously we don't want todo this with any of the magic formats where
QEMU has to remain in charge of updating metadata while active.
I see two likely approaches:
1. Add a parameter to the existing 'block_resize' command
'refreshonly=true|false'
2. Add a separate command 'block_refresh'
Both of these options would internally just re-read the capacity of the
BlockDriver image, and then notify the guest device.
Regards,
Daniel
--
|: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org -o- http://virt-manager.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [Qemu-devel] QEMU online guest disk resize wrt host block devices 2011-09-01 13:27 [Qemu-devel] QEMU online guest disk resize wrt host block devices Daniel P. Berrange @ 2011-09-01 14:05 ` Christoph Hellwig 2011-09-01 14:30 ` Daniel P. Berrange 2011-09-01 14:27 ` [Qemu-devel] QEMU online guest disk resize wrt host block devices Daniel P. Berrange 1 sibling, 1 reply; 10+ messages in thread From: Christoph Hellwig @ 2011-09-01 14:05 UTC (permalink / raw) To: Daniel P. Berrange; +Cc: qemu-devel, hch On Thu, Sep 01, 2011 at 02:27:55PM +0100, Daniel P. Berrange wrote: > I see two likely approaches: > > 1. Add a parameter to the existing 'block_resize' command > 'refreshonly=true|false' > > 2. Add a separate command 'block_refresh' I think all that you need is a to implement a bdrv_truncate method for host devices that simply checks if the new size smaller or equal to the device size, and return 0 in that case or an error otherwise. ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Qemu-devel] QEMU online guest disk resize wrt host block devices 2011-09-01 14:05 ` Christoph Hellwig @ 2011-09-01 14:30 ` Daniel P. Berrange 2011-09-01 15:55 ` Christoph Hellwig 0 siblings, 1 reply; 10+ messages in thread From: Daniel P. Berrange @ 2011-09-01 14:30 UTC (permalink / raw) To: Christoph Hellwig; +Cc: qemu-devel On Thu, Sep 01, 2011 at 04:05:26PM +0200, Christoph Hellwig wrote: > On Thu, Sep 01, 2011 at 02:27:55PM +0100, Daniel P. Berrange wrote: > > I see two likely approaches: > > > > 1. Add a parameter to the existing 'block_resize' command > > 'refreshonly=true|false' > > > > 2. Add a separate command 'block_refresh' > > I think all that you need is a to implement a bdrv_truncate method > for host devices that simply checks if the new size smaller or equal > to the device size, and return 0 in that case or an error otherwise. Hmm, yes that is another option. I'll see if I can cook up a patch for doing that. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Qemu-devel] QEMU online guest disk resize wrt host block devices 2011-09-01 14:30 ` Daniel P. Berrange @ 2011-09-01 15:55 ` Christoph Hellwig 2011-09-02 15:00 ` Daniel P. Berrange 2011-09-07 11:02 ` [Qemu-devel] [PATCH] block: allow resizing of images residing on host devices Christoph Hellwig 0 siblings, 2 replies; 10+ messages in thread From: Christoph Hellwig @ 2011-09-01 15:55 UTC (permalink / raw) To: Daniel P. Berrange; +Cc: Christoph Hellwig, qemu-devel Please try the attached (untested) patch: Index: qemu/block/raw-posix.c =================================================================== --- qemu.orig/block/raw-posix.c 2011-09-01 17:37:42.579651525 +0200 +++ qemu/block/raw-posix.c 2011-09-01 17:43:28.882967337 +0200 @@ -645,10 +645,23 @@ static void raw_close(BlockDriverState * static int raw_truncate(BlockDriverState *bs, int64_t offset) { BDRVRawState *s = bs->opaque; - if (s->type != FTYPE_FILE) - return -ENOTSUP; - if (ftruncate(s->fd, offset) < 0) + struct stat st; + + if (fstat(s->fd, &st)) return -errno; + + if (S_ISREG(st.st_mode)) { + if (ftruncate(s->fd, offset) < 0) + return -errno; + } else if (S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode)) { + if (offset > raw_getlength(bs)) { + return -EINVAL; + } + return 0; + + } else { + return -ENOTSUP; + } return 0; } @@ -1167,6 +1180,7 @@ static BlockDriver bdrv_host_device = { .bdrv_read = raw_read, .bdrv_write = raw_write, + .bdrv_truncate = raw_truncate, .bdrv_getlength = raw_getlength, .bdrv_get_allocated_file_size = raw_get_allocated_file_size, @@ -1288,6 +1302,7 @@ static BlockDriver bdrv_host_floppy = { .bdrv_read = raw_read, .bdrv_write = raw_write, + .bdrv_truncate = raw_truncate, .bdrv_getlength = raw_getlength, .bdrv_get_allocated_file_size = raw_get_allocated_file_size, @@ -1389,6 +1404,7 @@ static BlockDriver bdrv_host_cdrom = { .bdrv_read = raw_read, .bdrv_write = raw_write, + .bdrv_truncate = raw_truncate, .bdrv_getlength = raw_getlength, .bdrv_get_allocated_file_size = raw_get_allocated_file_size, @@ -1510,6 +1526,7 @@ static BlockDriver bdrv_host_cdrom = { .bdrv_read = raw_read, .bdrv_write = raw_write, + .bdrv_truncate = raw_truncate, .bdrv_getlength = raw_getlength, .bdrv_get_allocated_file_size = raw_get_allocated_file_size, ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Qemu-devel] QEMU online guest disk resize wrt host block devices 2011-09-01 15:55 ` Christoph Hellwig @ 2011-09-02 15:00 ` Daniel P. Berrange 2011-09-07 11:02 ` [Qemu-devel] [PATCH] block: allow resizing of images residing on host devices Christoph Hellwig 1 sibling, 0 replies; 10+ messages in thread From: Daniel P. Berrange @ 2011-09-02 15:00 UTC (permalink / raw) To: Christoph Hellwig; +Cc: qemu-devel On Thu, Sep 01, 2011 at 05:55:43PM +0200, Christoph Hellwig wrote: > Please try the attached (untested) patch: Yes, this patch worked succesfully with the following test case: $ dd if=/dev/zero of=loop.img bs=1M seek=100 count=0 $ losetup -f loop.img $ ./x86_64-softmmu/qemu-system-x86_64 -hda /dev/loop0 -monitor stdio (qemu) info block ide0-hd0: removable=0 file=/dev/loop0 sectors=204800 ro=0 drv=raw encrypted=0 ide1-cd0: removable=1 locked=0 [not inserted] floppy0: removable=1 locked=0 [not inserted] sd0: removable=1 locked=0 [not inserted] $ dd if=/dev/zero of=loop.img bs=1M seek=200 count=0 $ losetup -c /dev/loop0 (qemu) block_resize ide0-hd0 200 (qemu) info block ide0-hd0: removable=0 file=/dev/loop0 sectors=409600 ro=0 drv=raw encrypted=0 ide1-cd0: removable=1 locked=0 [not inserted] floppy0: removable=1 locked=0 [not inserted] sd0: removable=1 locked=0 [not inserted] Regards, Daniel > Index: qemu/block/raw-posix.c > =================================================================== > --- qemu.orig/block/raw-posix.c 2011-09-01 17:37:42.579651525 +0200 > +++ qemu/block/raw-posix.c 2011-09-01 17:43:28.882967337 +0200 > @@ -645,10 +645,23 @@ static void raw_close(BlockDriverState * > static int raw_truncate(BlockDriverState *bs, int64_t offset) > { > BDRVRawState *s = bs->opaque; > - if (s->type != FTYPE_FILE) > - return -ENOTSUP; > - if (ftruncate(s->fd, offset) < 0) > + struct stat st; > + > + if (fstat(s->fd, &st)) > return -errno; > + > + if (S_ISREG(st.st_mode)) { > + if (ftruncate(s->fd, offset) < 0) > + return -errno; > + } else if (S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode)) { > + if (offset > raw_getlength(bs)) { > + return -EINVAL; > + } > + return 0; > + > + } else { > + return -ENOTSUP; > + } > return 0; > } > > @@ -1167,6 +1180,7 @@ static BlockDriver bdrv_host_device = { > > .bdrv_read = raw_read, > .bdrv_write = raw_write, > + .bdrv_truncate = raw_truncate, > .bdrv_getlength = raw_getlength, > .bdrv_get_allocated_file_size > = raw_get_allocated_file_size, > @@ -1288,6 +1302,7 @@ static BlockDriver bdrv_host_floppy = { > > .bdrv_read = raw_read, > .bdrv_write = raw_write, > + .bdrv_truncate = raw_truncate, > .bdrv_getlength = raw_getlength, > .bdrv_get_allocated_file_size > = raw_get_allocated_file_size, > @@ -1389,6 +1404,7 @@ static BlockDriver bdrv_host_cdrom = { > > .bdrv_read = raw_read, > .bdrv_write = raw_write, > + .bdrv_truncate = raw_truncate, > .bdrv_getlength = raw_getlength, > .bdrv_get_allocated_file_size > = raw_get_allocated_file_size, > @@ -1510,6 +1526,7 @@ static BlockDriver bdrv_host_cdrom = { > > .bdrv_read = raw_read, > .bdrv_write = raw_write, > + .bdrv_truncate = raw_truncate, > .bdrv_getlength = raw_getlength, > .bdrv_get_allocated_file_size > = raw_get_allocated_file_size, ^ permalink raw reply [flat|nested] 10+ messages in thread
* [Qemu-devel] [PATCH] block: allow resizing of images residing on host devices 2011-09-01 15:55 ` Christoph Hellwig 2011-09-02 15:00 ` Daniel P. Berrange @ 2011-09-07 11:02 ` Christoph Hellwig 2011-09-09 9:37 ` Kevin Wolf 1 sibling, 1 reply; 10+ messages in thread From: Christoph Hellwig @ 2011-09-07 11:02 UTC (permalink / raw) To: qemu-devel Allow to resize images that reside on host devices up to the available space. This allows to grow images after resizing the device manually or vice versa. Reviewed-by: Christoph Hellwig <hch@lst.de> Index: qemu/block/raw-posix.c =================================================================== --- qemu.orig/block/raw-posix.c 2011-09-01 17:37:42.579651525 +0200 +++ qemu/block/raw-posix.c 2011-09-01 17:43:28.882967337 +0200 @@ -645,10 +645,23 @@ static void raw_close(BlockDriverState * static int raw_truncate(BlockDriverState *bs, int64_t offset) { BDRVRawState *s = bs->opaque; - if (s->type != FTYPE_FILE) - return -ENOTSUP; - if (ftruncate(s->fd, offset) < 0) + struct stat st; + + if (fstat(s->fd, &st)) return -errno; + + if (S_ISREG(st.st_mode)) { + if (ftruncate(s->fd, offset) < 0) + return -errno; + } else if (S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode)) { + if (offset > raw_getlength(bs)) { + return -EINVAL; + } + return 0; + + } else { + return -ENOTSUP; + } return 0; } @@ -1167,6 +1180,7 @@ static BlockDriver bdrv_host_device = { .bdrv_read = raw_read, .bdrv_write = raw_write, + .bdrv_truncate = raw_truncate, .bdrv_getlength = raw_getlength, .bdrv_get_allocated_file_size = raw_get_allocated_file_size, @@ -1288,6 +1302,7 @@ static BlockDriver bdrv_host_floppy = { .bdrv_read = raw_read, .bdrv_write = raw_write, + .bdrv_truncate = raw_truncate, .bdrv_getlength = raw_getlength, .bdrv_get_allocated_file_size = raw_get_allocated_file_size, @@ -1389,6 +1404,7 @@ static BlockDriver bdrv_host_cdrom = { .bdrv_read = raw_read, .bdrv_write = raw_write, + .bdrv_truncate = raw_truncate, .bdrv_getlength = raw_getlength, .bdrv_get_allocated_file_size = raw_get_allocated_file_size, @@ -1510,6 +1526,7 @@ static BlockDriver bdrv_host_cdrom = { .bdrv_read = raw_read, .bdrv_write = raw_write, + .bdrv_truncate = raw_truncate, .bdrv_getlength = raw_getlength, .bdrv_get_allocated_file_size = raw_get_allocated_file_size, ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Qemu-devel] [PATCH] block: allow resizing of images residing on host devices 2011-09-07 11:02 ` [Qemu-devel] [PATCH] block: allow resizing of images residing on host devices Christoph Hellwig @ 2011-09-09 9:37 ` Kevin Wolf 0 siblings, 0 replies; 10+ messages in thread From: Kevin Wolf @ 2011-09-09 9:37 UTC (permalink / raw) To: Christoph Hellwig; +Cc: qemu-devel Am 07.09.2011 13:02, schrieb Christoph Hellwig: > Allow to resize images that reside on host devices up to the available > space. This allows to grow images after resizing the device manually or > vice versa. > > Reviewed-by: Christoph Hellwig <hch@lst.de> You mean Signed-off-by, no? > Index: qemu/block/raw-posix.c > =================================================================== > --- qemu.orig/block/raw-posix.c 2011-09-01 17:37:42.579651525 +0200 > +++ qemu/block/raw-posix.c 2011-09-01 17:43:28.882967337 +0200 > @@ -645,10 +645,23 @@ static void raw_close(BlockDriverState * > static int raw_truncate(BlockDriverState *bs, int64_t offset) > { > BDRVRawState *s = bs->opaque; > - if (s->type != FTYPE_FILE) > - return -ENOTSUP; > - if (ftruncate(s->fd, offset) < 0) > + struct stat st; > + > + if (fstat(s->fd, &st)) > return -errno; Coding style requires braces. > + > + if (S_ISREG(st.st_mode)) { > + if (ftruncate(s->fd, offset) < 0) > + return -errno; Here as well. > + } else if (S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode)) { > + if (offset > raw_getlength(bs)) { > + return -EINVAL; > + } > + return 0; This return isn't needed and it's not there in the S_ISREG case. It should be symmetrical at least. Semantically the patch looks okay. Kevin ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Qemu-devel] QEMU online guest disk resize wrt host block devices 2011-09-01 13:27 [Qemu-devel] QEMU online guest disk resize wrt host block devices Daniel P. Berrange 2011-09-01 14:05 ` Christoph Hellwig @ 2011-09-01 14:27 ` Daniel P. Berrange 2011-09-01 15:56 ` Christoph Hellwig 1 sibling, 1 reply; 10+ messages in thread From: Daniel P. Berrange @ 2011-09-01 14:27 UTC (permalink / raw) To: qemu-devel; +Cc: hch On Thu, Sep 01, 2011 at 02:27:55PM +0100, Daniel P. Berrange wrote: > We want to support online resize of guest disks in the libvirt API for > QEMU, and had intended to use the fairly recently added 'block_resize' > command: > > commit db97ee6a976bacbb0d18818e951cfc41b39269a7 > Author: Christoph Hellwig <hch@lst.de> > Date: Mon Jan 24 13:32:41 2011 +0100 > > block: tell drivers about an image resize > > commit 6d4a2b3a47959f02e7f307f50396e70e8464f95e > Author: Christoph Hellwig <hch@lst.de> > Date: Mon Jan 24 13:32:33 2011 +0100 > > block: add block_resize monitor command > > There is unfortunately a problem with the design of this monitor command > because it has tied the task of resizing the host backing file for the > virtual disk, together with the task of notifying the guest device of the > block resize. This means that we can only use 'block_resize' for disks > that are backed by image files (raw, qcow2, etc) that QEMU can actually > resize. One other question too, when creating a qcow2 image via 'qemu-img create' you can specify a 'prealloc' option to require metadata to be allocated at time of creation. Should we have the same control at time of resize too. If the app had originally created the qcow2 image with preallocated metadata, then I'd expect they want to pre-allocate metadata when extending it too, or is there no additional metadata allocation required when extending an image ? Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Qemu-devel] QEMU online guest disk resize wrt host block devices 2011-09-01 14:27 ` [Qemu-devel] QEMU online guest disk resize wrt host block devices Daniel P. Berrange @ 2011-09-01 15:56 ` Christoph Hellwig 2011-09-05 13:03 ` Kevin Wolf 0 siblings, 1 reply; 10+ messages in thread From: Christoph Hellwig @ 2011-09-01 15:56 UTC (permalink / raw) To: Daniel P. Berrange; +Cc: qemu-devel, hch On Thu, Sep 01, 2011 at 03:27:35PM +0100, Daniel P. Berrange wrote: > One other question too, when creating a qcow2 image via 'qemu-img create' > you can specify a 'prealloc' option to require metadata to be allocated > at time of creation. > > Should we have the same control at time of resize too. If the app had > originally created the qcow2 image with preallocated metadata, then > I'd expect they want to pre-allocate metadata when extending it too, > or is there no additional metadata allocation required when extending > an image ? Sounds reasonable. Keving, is there a sane way to implement this? > > > Daniel > -- > |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| > |: http://libvirt.org -o- http://virt-manager.org :| > |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| > |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| ---end quoted text--- ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Qemu-devel] QEMU online guest disk resize wrt host block devices 2011-09-01 15:56 ` Christoph Hellwig @ 2011-09-05 13:03 ` Kevin Wolf 0 siblings, 0 replies; 10+ messages in thread From: Kevin Wolf @ 2011-09-05 13:03 UTC (permalink / raw) To: Christoph Hellwig; +Cc: qemu-devel Am 01.09.2011 17:56, schrieb Christoph Hellwig: > On Thu, Sep 01, 2011 at 03:27:35PM +0100, Daniel P. Berrange wrote: >> One other question too, when creating a qcow2 image via 'qemu-img create' >> you can specify a 'prealloc' option to require metadata to be allocated >> at time of creation. >> >> Should we have the same control at time of resize too. If the app had >> originally created the qcow2 image with preallocated metadata, then >> I'd expect they want to pre-allocate metadata when extending it too, >> or is there no additional metadata allocation required when extending >> an image ? > > Sounds reasonable. Keving, is there a sane way to implement this? Implementing the functionality itself shouldn't be a big problem. The big question is what the right interface would look like. We have driver specific preallocation options, so we would end up with something like this: bdrv_truncate(bs, int64_t size, char* prealloc_mode). Not exactly nice. And is preallocation the only thing or would we need to pass a whole option list like for image creation? Of course, if this is a real requirement and not only a random thought, we can always introduce a specific flag for the current use case and add the generic thing only later when we have thought a bit more about it. Kevin ^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2011-09-09 9:35 UTC | newest] Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2011-09-01 13:27 [Qemu-devel] QEMU online guest disk resize wrt host block devices Daniel P. Berrange 2011-09-01 14:05 ` Christoph Hellwig 2011-09-01 14:30 ` Daniel P. Berrange 2011-09-01 15:55 ` Christoph Hellwig 2011-09-02 15:00 ` Daniel P. Berrange 2011-09-07 11:02 ` [Qemu-devel] [PATCH] block: allow resizing of images residing on host devices Christoph Hellwig 2011-09-09 9:37 ` Kevin Wolf 2011-09-01 14:27 ` [Qemu-devel] QEMU online guest disk resize wrt host block devices Daniel P. Berrange 2011-09-01 15:56 ` Christoph Hellwig 2011-09-05 13:03 ` Kevin Wolf
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.