[PATCH] xfs: fix sub-page blocksize data integrity writes

[Dave Chinner]

On Thu, May 02, 2013 at 05:45:09PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner at redhat.com>
> 
> FSX on 512 byte block size filesystems has been failing for some
> time with corrupted data. The fault dates back to the change in
> the writeback data integrity algorithm that uses a mark-and-sweep
> approach to avoid data writeback livelocks.
.....
> +	 * time this will be the only page inteh file that needs writeback.
> +	 * Hence for more optimal IO patterns, we should always avoid partial
> +	 * page writeback due to multiple mappings on a page here.
> +	 */
> +	if (!xfs_imap_valid(inode, imap, end_offset))
> +		goto fail_unlock_page;
> +
>  	len = 1 << inode->i_blkbits;
>  	p_offset = min_t(unsigned long, end_offset & (PAGE_CACHE_SIZE - 1),
>  					PAGE_CACHE_SIZE);
>  	p_offset = p_offset ? roundup(p_offset, len) : PAGE_CACHE_SIZE;
>  	page_dirty = p_offset / len;
>  
> +

Oh, stray whitespace....

>  	bh = head = page_buffers(page);
>  	do {
>  		if (offset >= end_offset)
> diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
> index 1501f4f..0176bb2 100644
> --- a/fs/xfs/xfs_vnodeops.c
> +++ b/fs/xfs/xfs_vnodeops.c
> @@ -1453,7 +1453,7 @@ xfs_free_file_space(
>  	xfs_mount_t		*mp;
>  	int			nimap;
>  	uint			resblks;
> -	uint			rounding;
> +	xfs_off_t		rounding;
>  	int			rt;
>  	xfs_fileoff_t		startoffset_fsb;
>  	xfs_trans_t		*tp;
> @@ -1482,7 +1482,7 @@ xfs_free_file_space(
>  		inode_dio_wait(VFS_I(ip));
>  	}
>  
> -	rounding = max_t(uint, 1 << mp->m_sb.sb_blocklog, PAGE_CACHE_SIZE);
> +	rounding = max_t(xfs_off_t, 1 << mp->m_sb.sb_blocklog, PAGE_CACHE_SIZE);
>  	ioffset = offset & ~(rounding - 1);
>  	error = -filemap_write_and_wait_range(VFS_I(ip)->i_mapping,
>  					      ioffset, -1);

And I forgot I had noticed a second problem while dealing with this
one (i.e. the rounding masks is wrong for offsets > 32 bits)....

I'll repost them both as separate patches.

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com