Re: [PATCH 6/6] xfs: fold xfs_ilock_for_write_fault into xfs_write_fault

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Jun 19, 2024 at 01:53:56PM +0200, Christoph Hellwig wrote:
> Now that the page fault handler has been refactored, the only caller
> of xfs_ilock_for_write_fault is simple enough and calls it
> unconditionally.  Fold the logic and expand the comments explaining it.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Makes sense to me,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/xfs/xfs_file.c | 33 +++++++++++++++------------------
>  1 file changed, 15 insertions(+), 18 deletions(-)
> 
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 62a69ed796f2fd..05ea96661c475f 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -227,21 +227,6 @@ xfs_ilock_iocb_for_write(
>  	return 0;
>  }
>  
> -static unsigned int
> -xfs_ilock_for_write_fault(
> -	struct xfs_inode	*ip)
> -{
> -	/* get a shared lock if no remapping in progress */
> -	xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
> -	if (!xfs_iflags_test(ip, XFS_IREMAPPING))
> -		return XFS_MMAPLOCK_SHARED;
> -
> -	/* wait for remapping to complete */
> -	xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
> -	xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
> -	return XFS_MMAPLOCK_EXCL;
> -}
> -
>  STATIC ssize_t
>  xfs_file_dio_read(
>  	struct kiocb		*iocb,
> @@ -1294,18 +1279,30 @@ xfs_write_fault(
>  	unsigned int		order)
>  {
>  	struct inode		*inode = file_inode(vmf->vma->vm_file);
> -	unsigned int		lock_mode;
> +	struct xfs_inode	*ip = XFS_I(inode);
> +	unsigned int		lock_mode = XFS_MMAPLOCK_SHARED;
>  	vm_fault_t		ret;
>  
>  	sb_start_pagefault(inode->i_sb);
>  	file_update_time(vmf->vma->vm_file);
>  
> -	lock_mode = xfs_ilock_for_write_fault(XFS_I(inode));
> +	/*
> +	 * Normally we only need the shared mmaplock, but if a reflink remap is
> +	 * in progress we take the exclusive lock to wait for the remap to
> +	 * finish before taking a write fault.
> +	 */
> +	xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
> +	if (xfs_iflags_test(ip, XFS_IREMAPPING)) {
> +		xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
> +		xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
> +		lock_mode = XFS_MMAPLOCK_EXCL;
> +	}
> +
>  	if (IS_DAX(inode))
>  		ret = xfs_dax_fault_locked(vmf, order, true);
>  	else
>  		ret = iomap_page_mkwrite(vmf, &xfs_page_mkwrite_iomap_ops);
> -	xfs_iunlock(XFS_I(inode), lock_mode);
> +	xfs_iunlock(ip, lock_mode);
>  
>  	sb_end_pagefault(inode->i_sb);
>  	return ret;
> -- 
> 2.43.0
> 
>