Re: [PATCH 08/18] xfs: remove xfs_reflink_find_cow_mapping

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, May 30, 2018 at 12:00:03PM +0200, Christoph Hellwig wrote:
> We only have one caller left, and open coding the simple extent list
> lookup in it allows us to make the code both more understandable and
> reuse calculations and variables already present.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
>  fs/xfs/xfs_aops.c    | 17 ++++++++++++-----
>  fs/xfs/xfs_reflink.c | 30 ------------------------------
>  fs/xfs/xfs_reflink.h |  2 --
>  fs/xfs/xfs_trace.h   |  1 -
>  4 files changed, 12 insertions(+), 38 deletions(-)
> 
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index 8cc41a786b5e..e2671b223409 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -385,6 +385,7 @@ xfs_map_blocks(
>  	ssize_t			count = i_blocksize(inode);
>  	xfs_fileoff_t		offset_fsb, end_fsb;
>  	int			whichfork = XFS_DATA_FORK;
> +	struct xfs_iext_cursor	icur;
>  	int			error = 0;
>  	int			nimaps = 1;
>  
> @@ -396,8 +397,18 @@ xfs_map_blocks(
>  	       (ip->i_df.if_flags & XFS_IFEXTENTS));
>  	ASSERT(offset <= mp->m_super->s_maxbytes);
>  
> +	if (offset > mp->m_super->s_maxbytes - count)
> +		count = mp->m_super->s_maxbytes - offset;
> +	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
> +	offset_fsb = XFS_B_TO_FSBT(mp, offset);
> +
> +	/*
> +	 * Check if this is offset is covered by a COW extents, and if yes use
> +	 * it directly instead of looking up anything in the data fork.
> +	 */
>  	if (xfs_is_reflink_inode(ip) &&
> -	    xfs_reflink_find_cow_mapping(ip, offset, imap)) {
> +	    xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, imap) &&
> +	    imap->br_startoff <= offset_fsb) {
>  		xfs_iunlock(ip, XFS_ILOCK_SHARED);
>  		/*
>  		 * Truncate can race with writeback since writeback doesn't
> @@ -417,10 +428,6 @@ xfs_map_blocks(
>  		goto allocate_blocks;
>  	}
>  
> -	if (offset > mp->m_super->s_maxbytes - count)
> -		count = mp->m_super->s_maxbytes - offset;
> -	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
> -	offset_fsb = XFS_B_TO_FSBT(mp, offset);
>  	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
>  				imap, &nimaps, XFS_BMAPI_ENTIRE);
>  	if (!nimaps) {
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 713e857d9ffa..8e5eb8e70c89 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -484,36 +484,6 @@ xfs_reflink_allocate_cow(
>  	return error;
>  }
>  
> -/*
> - * Find the CoW reservation for a given byte offset of a file.
> - */
> -bool
> -xfs_reflink_find_cow_mapping(
> -	struct xfs_inode		*ip,
> -	xfs_off_t			offset,
> -	struct xfs_bmbt_irec		*imap)
> -{
> -	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
> -	xfs_fileoff_t			offset_fsb;
> -	struct xfs_bmbt_irec		got;
> -	struct xfs_iext_cursor		icur;
> -
> -	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
> -
> -	if (!xfs_is_reflink_inode(ip))
> -		return false;
> -	offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
> -	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
> -		return false;
> -	if (got.br_startoff > offset_fsb)
> -		return false;
> -
> -	trace_xfs_reflink_find_cow_mapping(ip, offset, 1, XFS_IO_OVERWRITE,
> -			&got);
> -	*imap = got;
> -	return true;
> -}
> -
>  /*
>   * Trim an extent to end at the next CoW reservation past offset_fsb.
>   */
> diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h
> index 701487bab468..15a456492667 100644
> --- a/fs/xfs/xfs_reflink.h
> +++ b/fs/xfs/xfs_reflink.h
> @@ -32,8 +32,6 @@ extern int xfs_reflink_allocate_cow(struct xfs_inode *ip,
>  		struct xfs_bmbt_irec *imap, bool *shared, uint *lockmode);
>  extern int xfs_reflink_convert_cow(struct xfs_inode *ip, xfs_off_t offset,
>  		xfs_off_t count);
> -extern bool xfs_reflink_find_cow_mapping(struct xfs_inode *ip, xfs_off_t offset,
> -		struct xfs_bmbt_irec *imap);
>  extern void xfs_reflink_trim_irec_to_next_cow(struct xfs_inode *ip,
>  		xfs_fileoff_t offset_fsb, struct xfs_bmbt_irec *imap);
>  
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 9d4c4ca24fe6..ed8f774944ba 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -3227,7 +3227,6 @@ DEFINE_INODE_IREC_EVENT(xfs_reflink_convert_cow);
>  DEFINE_RW_EVENT(xfs_reflink_reserve_cow);
>  
>  DEFINE_SIMPLE_IO_EVENT(xfs_reflink_bounce_dio_write);
> -DEFINE_IOMAP_EVENT(xfs_reflink_find_cow_mapping);
>  DEFINE_INODE_IREC_EVENT(xfs_reflink_trim_irec);
>  
>  DEFINE_SIMPLE_IO_EVENT(xfs_reflink_cancel_cow_range);
> -- 
> 2.17.0
> 
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