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Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for
From: |
Christoph Hellwig |
Subject: |
Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations |
Date: |
Sat, 24 Mar 2012 16:27:21 +0100 |
User-agent: |
Mutt/1.5.17 (2007-11-01) |
On Sat, Mar 10, 2012 at 12:02:40PM -0600, Richard Laager wrote:
> If we could probe for FALLOC_FL_PUNCH_HOLE support, then we could avoid
> advertising discard support based on FALLOC_FL_PUNCH_HOLE when it is not
> going to work. This would side step these problems. You said it wasn't
> possible to probe for FALLOC_FL_PUNCH_HOLE. Have you considered probing
> by extending the file by one byte and then punching that:
> char buf = 0;
> fstat(s->fd, &st);
> pwrite(s->fd, &buf, 1, st.st_size + 1);
> has_discard = !fallocate(s->fd, FALLOC_FL_PUNCH_HOLE |
> FALLOC_FL_KEEP_SIZE,
There is no point in using FALLOC_FL_KEEP_SIZE together with
FALLOC_FL_PUNCH_HOLE.
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, (continued)
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Christoph Hellwig, 2012/03/24
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Daniel P. Berrange, 2012/03/26
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Christoph Hellwig, 2012/03/26
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Richard Laager, 2012/03/14
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Paolo Bonzini, 2012/03/15
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Richard Laager, 2012/03/15
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Paolo Bonzini, 2012/03/16
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations,
Christoph Hellwig <=
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Richard Laager, 2012/03/26
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Christoph Hellwig, 2012/03/27
[Qemu-devel] [RFC PATCH 04/17] qed: implement bdrv_aio_discard, Paolo Bonzini, 2012/03/08
[Qemu-devel] [RFC PATCH 10/17] ide/scsi: add discard_zeroes_data property, Paolo Bonzini, 2012/03/08
[Qemu-devel] [RFC PATCH 09/17] ide: issue discard asynchronously but serialize the pieces, Paolo Bonzini, 2012/03/08
[Qemu-devel] [RFC PATCH 05/17] block: pass around qiov for write_zeroes operation, Paolo Bonzini, 2012/03/08