Re: [PATCH] Introduce SEEK_DATA/SEEK_HOLE support V8

Mark Tinguely
2012-02-21T14:56:04Z

On 02/17/12 07:16, Jeff Liu wrote:
> Hello,
>
> This is the revised patch according to Dave's comments for V7.
>
> Changes to V8:
> --------------
> 1. If there is an internal error raised at extent reading routine, just
> return it rather than ENXIO.
> 2. Add the commit message.
> 3. Remove the for(;;) loop since there is no continuous holes shown even
> if create a Petabyte sparse file with hole extent length longer than
> 32-bit. Thanks Dave for helping verify that!
> 4. In xfs_seek_data(), s/len/end/, looks 'end' is more meaningful here
> to indicate the range of extents mapped.
> 5. Remove BUG() from xfs_seek_data() since xfs_bmapi_read() have found
> any corruption during the lookup, it should not occurred at all.
>
> Any comments are appreciated!
>
> Thanks,
> -Jeff
>
>
> Signed-off-by: Jie Liu<jeff.liu@oracle.com>

...

> +STATIC loff_t
> +xfs_seek_hole(
...
> +
> + fsbno = XFS_B_TO_FSBT(mp, start);
> + error = xfs_bmap_first_unused(NULL, ip, 1,&fsbno, XFS_DATA_FORK);
> + if (error)
> + goto out_unlock;
> +
> + holeoff = XFS_FSB_TO_B(mp, fsbno);
> + if (holeoff<= start)
> + offset = start;
> + else
> + offset = min_t(loff_t, holeoff, isize);
> +

...

Very Nice. Much more concise.

Can xfs_bmap_first_unused() return something larger than the end of file?

Reviewed-by: Mark Tinguely <tinguely@sgi.com>