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Date: Fri, 17 Dec 2010 11:32:45 +0100
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 3/3] raw-posix: add discard support
References: <20101210150038.GA30990@lst.de> <20101216183614.GA17260@lst.de>
	<20101216183656.GC17521@lst.de>
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To: Christoph Hellwig <hch@lst.de>
Cc: qemu-devel@nongnu.org

Am 16.12.2010 19:36, schrieb Christoph Hellwig:
> Add support to discard blocks in a raw image residing on an XFS filesystem
> by calling the XFS_IOC_UNRESVSP64 ioctl to punch holes.  Support for other
> hole punching mechanisms can be added when they become available.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> Index: qemu/block/raw-posix.c
> ===================================================================
> --- qemu.orig/block/raw-posix.c	2010-12-15 10:05:37.000000000 +0100
> +++ qemu/block/raw-posix.c	2010-12-16 17:40:47.617253460 +0100
> @@ -69,6 +69,10 @@
>  #include <sys/diskslice.h>
>  #endif
>  
> +#ifdef CONFIG_XFS
> +#include <xfs/xfs.h>
> +#endif
> +
>  //#define DEBUG_FLOPPY
>  
>  //#define DEBUG_BLOCK
> @@ -120,6 +124,9 @@ typedef struct BDRVRawState {
>  #endif
>      uint8_t *aligned_buf;
>      unsigned aligned_buf_size;
> +#ifdef CONFIG_XFS
> +    bool is_xfs : 1;
> +#endif
>  } BDRVRawState;
>  
>  static int fd_open(BlockDriverState *bs);
> @@ -196,6 +203,12 @@ static int raw_open_common(BlockDriverSt
>  #endif
>      }
>  
> +#ifdef CONFIG_XFS
> +    if (platform_test_xfs_fd(s->fd)) {
> +        s->is_xfs = 1;
> +    }
> +#endif
> +
>      return 0;
>  
>  out_free_buf:
> @@ -740,6 +753,36 @@ static int raw_flush(BlockDriverState *b
>      return qemu_fdatasync(s->fd);
>  }
>  
> +#ifdef CONFIG_XFS
> +static int xfs_discard(BDRVRawState *s, int64_t sector_num, int nb_sectors)
> +{
> +    struct xfs_flock64 fl;
> +
> +    memset(&fl, 0, sizeof(fl));
> +    fl.l_whence = SEEK_SET;
> +    fl.l_start = sector_num << 9;
> +    fl.l_len = (int64_t)nb_sectors << 9;
> +
> +    if (xfsctl(NULL, s->fd, XFS_IOC_UNRESVSP64, &fl) < 0) {
> +        printf("cannot punch hole (%s)\n", strerror(errno));

Debugging leftover? Block drivers shouldn't print anything to stdout.

> +        return -errno;
> +    }
> +
> +    return 0;
> +}
> +#endif
> +
> +static int raw_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors)
> +{
> +#ifdef CONFIG_XFS
> +    BDRVRawState *s = bs->opaque;
> +
> +    if (s->is_xfs)
> +        return xfs_discard(s, sector_num, nb_sectors);

Missing braces.

I have already applied patch 1 and 2 to the block branch, so sending a
v5 for this one is enough.

Kevin