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Date: Fri, 04 Nov 2011 11:05:03 +0100
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [v8 Patch 5/6]Qemu: Framework for reopening images
 safely
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To: Supriya Kannery <supriyak@linux.vnet.ibm.com>
Cc: Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel@nongnu.org, Christoph Hellwig <hch@lst.de>

Am 30.10.2011 11:35, schrieb Supriya Kannery:
> Struct BDRVReopenState along with three reopen related functions
> introduced for handling reopen state of images safely. This can be
> extended by each of the block drivers to reopen respective
> image files.
> 
> Signed-off-by: Supriya Kannery <supriyak@linux.vnet.ibm.com>

> Index: qemu/block_int.h
> ===================================================================
> --- qemu.orig/block_int.h
> +++ qemu/block_int.h
> @@ -55,6 +55,14 @@ struct BlockDriver {
>      int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename);
>      int (*bdrv_probe_device)(const char *filename);
>      int (*bdrv_open)(BlockDriverState *bs, int flags);
> +
> +    /* For handling image reopen for split or non-split files */
> +    int (*bdrv_reopen_prepare)(BlockDriverState *bs, BDRVReopenState **rs,
> +          int flags);
> +    void (*bdrv_reopen_commit)(BlockDriverState *bs, BDRVReopenState *rs,
> +          int flags);
> +    void (*bdrv_reopen_abort)(BlockDriverState *bs, BDRVReopenState *rs);
> +
>      int (*bdrv_file_open)(BlockDriverState *bs, const char *filename, int flags);
>      int (*bdrv_read)(BlockDriverState *bs, int64_t sector_num,
>                       uint8_t *buf, int nb_sectors);
> @@ -211,6 +219,14 @@ struct BlockDriverState {
>      void *private;
>  };
>  
> +struct BDRVReopenState {
> +    BlockDriverState *bs;
> +    int reopen_flags;
> +
> +    /* For raw-posix */
> +    int reopen_fd;
> +};

I think I commented the same on the previous version: BDRVReopenState
shouldn't contain any format specific fields. raw-posix must extend the
struct like this and use container_of() to get it from a BDRVReopenState
pointer:

struct BDRVRawReopenState {
    BDRVReopenState common;
    int reopen_fd;
};

Kevin