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Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols |
Date: |
Thu, 7 May 2015 14:29:11 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Am 07.05.2015 um 14:20 hat Paolo Bonzini geschrieben:
>
>
> On 06/05/2015 19:23, Max Reitz wrote:
> > The guest sees whatever has been written into reply->error, and that
> > field hasn't been written by this function in that case. It has been
> > written by nbd_receive_reply() in nbd.c, and that value comes directly
> > from the server. In case of qemu-nbd being the server, a write beyond
> > the EOF should be caught by blk_check_byte_request() in
> > block/block-backend.c, which returns -EIO. So that's where the EIO comes
> > from.
>
> Fair enough. This makes sense, but then we have to create ENOSPC elsewhere.
>
> > I don't know whether this EIO is subsequently converted to ENOSPC
> > because of werror=enospc, but considering that
> > https://bugzilla.redhat.com/show_bug.cgi?id=1090713 did not override
> > werror, it doesn't look like it.
>
> No, it shouldn't indeed.
>
> Could alloc_clusters_noref do bdrv_truncate and return ENOSPC if it
> fails? That's how for example qcow and vhdx work. vdi has the same
> problem.
If you want NBD to return -ENOSPC for writes after EOF, change the
nbd block driver to do just that. There's no reason to add additional
overhead to qcow2 (even over raw-posix) for that.
Kevin
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Stefan Hajnoczi, 2015/05/05
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Max Reitz, 2015/05/06
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Paolo Bonzini, 2015/05/06
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Max Reitz, 2015/05/06
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Paolo Bonzini, 2015/05/06
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Max Reitz, 2015/05/06
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Paolo Bonzini, 2015/05/06
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Max Reitz, 2015/05/06
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Paolo Bonzini, 2015/05/07
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols,
Kevin Wolf <=
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Paolo Bonzini, 2015/05/07
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Kevin Wolf, 2015/05/07
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Paolo Bonzini, 2015/05/07
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Kevin Wolf, 2015/05/07
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Paolo Bonzini, 2015/05/07
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Kevin Wolf, 2015/05/07
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Paolo Bonzini, 2015/05/07
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Kevin Wolf, 2015/05/08
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Paolo Bonzini, 2015/05/08
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols, Kevin Wolf, 2015/05/08