Re: [Qemu-devel] QEMU online guest disk resize wrt host block devices

["Daniel P. Berrange" <berrange@redhat.com>]

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,