On Fri, Nov 23, 2012 at 02:24:25PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> XFS_IOC_ZERO_RANGE simply does not work properly for non page cache
> aligned ranges. Neither test 242 or 290 exercise this correctly, so
> the behaviour is completely busted even though the tests pass.
>
> Fix it to support full byte range granularity as was originally
> intended for this ioctl.
Looks good, but a couple cosmetic comments below:
> + rounding = max_t(uint, 1 << mp->m_sb.sb_blocklog, PAGE_CACHE_SIZE);
I'd call this granularity.
> + /* round the range iof extents we are going to convert inwards */
> + start = round_up(offset, rounding);
> + end = round_down(offset + len, rounding);
start_boundary, end_boundary?
> + if (start < end - 1) {
> + /* punch out the page cache over the conversion range */
> + truncate_pagecache_range(VFS_I(ip), start, end - 1);
> + /* convert the blocks */
> + error = xfs_alloc_file_space(ip, start, end - start - 1,
> + XFS_BMAPI_PREALLOC | XFS_BMAPI_CONVERT,
> + attr_flags);
> + if (error)
> + goto out_unlock;
> + } else {
> + /* it's a sub-rounding range */
> + ASSERT(offset + len <= start);
> + error = xfs_iozero(ip, offset, len);
> + goto out_unlock;
> + }
> +
> + /* now we've handled the interior of the range, handle the edges */
> + if (start != offset)
> + error = xfs_iozero(ip, offset, start - offset);
> + if (!error && end != offset + len)
> + error = xfs_iozero(ip, end, offset + len - end);
I'd move the edge iozero calls into the if branch, that gives a natural
code flow and avoids the goto unlock in the sub-page case.
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