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Re: [Qemu-devel] [PATCH 5/5] block: Always enable discard on the protoco
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 5/5] block: Always enable discard on the protocol level |
Date: |
Thu, 13 Jun 2013 18:06:02 -0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 |
Il 13/06/2013 07:47, Kevin Wolf ha scritto:
> Turning on discard options in qcow2 doesn't help a lot when the discard
> requests that it issues are thrown away by the raw-posix layer. This
> patch always enables discard functionality on the protocol level so that
> it's the image format's responsibility to send (or not) discard
> requests. Requests sent by the guest will be allowed or ignored by the
> top level BlockDriverState, which depends on the discard=... option like
> before.
>
> In particular, this means that even without specifying options, the
> qcow2 default of discarding deleted snapshots actually takes effect now,
> both for qemu and qemu-img.
>
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
> block.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/block.c b/block.c
> index 79ad33d..0a7cf2f 100644
> --- a/block.c
> +++ b/block.c
> @@ -1045,7 +1045,7 @@ int bdrv_open(BlockDriverState *bs, const char
> *filename, QDict *options,
> extract_subqdict(options, &file_options, "file.");
>
> ret = bdrv_file_open(&file, filename, file_options,
> - bdrv_open_flags(bs, flags));
> + bdrv_open_flags(bs, flags | BDRV_O_UNMAP));
> if (ret < 0) {
> goto fail;
> }
>
Can you still disable it with -drive file.discard=ignore?
Paolo
- Re: [Qemu-devel] [PATCH 3/5] qcow2: Options to enable discard for freed clusters, (continued)
Re: [Qemu-devel] [PATCH 3/5] qcow2: Options to enable discard for freed clusters, Stefan Hajnoczi, 2013/06/17
[Qemu-devel] [PATCH 2/5] qcow2: Add refcount update reason to all callers, Kevin Wolf, 2013/06/13
[Qemu-devel] [PATCH 4/5] qcow2: Batch discards, Kevin Wolf, 2013/06/13
[Qemu-devel] [PATCH 5/5] block: Always enable discard on the protocol level, Kevin Wolf, 2013/06/13
- Re: [Qemu-devel] [PATCH 5/5] block: Always enable discard on the protocol level,
Paolo Bonzini <=
Re: [Qemu-devel] [PATCH 0/5] qcow2: Discard freed clusters, Wenchao Xia, 2013/06/17