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Date: Thu, 25 Oct 2012 09:42:37 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] qemu-img convert with block driver without
 .bdrv_create (like iscsi)
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To: Alexandre DERUMIER <aderumier@odiso.com>
Cc: kwolf@redhat.com, qemu-devel <qemu-devel@nongnu.org>, ronnie sahlberg <ronniesahlberg@gmail.com>

Il 25/10/2012 09:25, Alexandre DERUMIER ha scritto:
> What is the best way to get it working ?
> 
> 1)add a .bdrv_create in block/iscsi.c ? 
> 
> (like host_device block driver, only open/close the device and check if size if big enough)
> 
>     if (fstat(fd, &stat_buf) < 0)
>         ret = -errno;
>     else if (!S_ISBLK(stat_buf.st_mode) && !S_ISCHR(stat_buf.st_mode))
>         ret = -ENODEV;

I'm not even sure this S_ISBLK/S_ISCHR test is necessary.

>     else if (lseek(fd, 0, SEEK_END) < total_size * BDRV_SECTOR_SIZE)
>         ret = -ENOSPC;
> 
>     qemu_close(fd);
>     return ret;
> }
> 
> 
> 2)or add a fallback in qemu-img, if bdrv_create doesn't exist, use bdrv_open to see if the backend device is pre-existing ?

Or even add it in block.c, so that it also applies to live snapshots etc.

Paolo