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Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on c
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert |
Date: |
Thu, 18 Jul 2013 16:14:36 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 |
Il 18/07/2013 15:55, ronnie sahlberg ha scritto:
>> > bdrv->write_zeroes will use writesame16 and set the unmap flag only if
>> > BDRV_MAY_DISCARD == 1 and BDRV_O_UNMAP == 1 and lbprz == 1.
> When you use WRITESAME16 you can ignore the lbprz flag.
> Just send a WRITESAME16 command with one block of data that is all set to
> zero.
> If the unmap flag is set and if unmapped blocks read back the same as
> the block you provided (all zero)
> then it will unmap those blocks, where possible.
True, so the unmap flag can be set iff BDRV_MAY_DISCARD == 1. block.c
can take care of checking BDRV_O_UNMAP.
Paolo
> All other blocks that can not be unmapped, or where unmapped blocks
> will not read back the same, will instead be overwritten by the
> provided all-zero block.
>
>
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, (continued)
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Kevin Wolf, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Peter Lieven, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Peter Lieven, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Peter Lieven, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Peter Lieven, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, ronnie sahlberg, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, ronnie sahlberg, 2013/07/17
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Kevin Wolf, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Peter Lieven, 2013/07/17
Re: [Qemu-devel] [PATCH 0/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/16
- Re: [Qemu-devel] [PATCH 0/4] qemu-img: conditionally discard target on convert, Peter Lieven, 2013/07/16
- Re: [Qemu-devel] [PATCH 0/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/16
- Re: [Qemu-devel] [PATCH 0/4] qemu-img: conditionally discard target on convert, Peter Lieven, 2013/07/16
- Re: [Qemu-devel] [PATCH 0/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/16
- Re: [Qemu-devel] [PATCH 0/4] qemu-img: conditionally discard target on convert, Peter Lieven, 2013/07/17
- Re: [Qemu-devel] [PATCH 0/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/17