Re: [PATCH 5.4] xfs: flush for older, xfs specific ioctls

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

On Thu, Nov 05, 2020 at 08:28:50PM +0000, Andy Strohman wrote:
> 837a6e7f5cdb ("fs: add generic UNRESVSP and ZERO_RANGE ioctl handlers") changed
> ioctls XFS_IOC_UNRESVSP XFS_IOC_UNRESVSP64 and XFS_IOC_ZERO_RANGE to be generic
> instead of xfs specific.
> 
> Because of this change, 36f11775da75 ("xfs: properly serialise fallocate against
> AIO+DIO") needed adaptation, as 5.4 still uses the xfs specific ioctls.
> 
> Without this, xfstests xfs/242 and xfs/290 fail. Both of these tests test
> XFS_IOC_ZERO_RANGE.
> 
> Fixes: 36f11775da75 ("xfs: properly serialise fallocate against AIO+DIO")
>
> Tested-by: Andy Strohman <astroh@amazon.com>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

Yeah, looks good to me,

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

--D

> ---
>  fs/xfs/xfs_ioctl.c | 26 +++++++++++++++++++++++++-
>  1 file changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index bf0435dbec43..b3021d9b34a5 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -622,7 +622,6 @@ xfs_ioc_space(
>  	error = xfs_break_layouts(inode, &iolock, BREAK_UNMAP);
>  	if (error)
>  		goto out_unlock;
> -	inode_dio_wait(inode);
>  
>  	switch (bf->l_whence) {
>  	case 0: /*SEEK_SET*/
> @@ -668,6 +667,31 @@ xfs_ioc_space(
>  		goto out_unlock;
>  	}
>  
> +	/*
> +	 * Must wait for all AIO to complete before we continue as AIO can
> +	 * change the file size on completion without holding any locks we
> +	 * currently hold. We must do this first because AIO can update both
> +	 * the on disk and in memory inode sizes, and the operations that follow
> +	 * require the in-memory size to be fully up-to-date.
> +	 */
> +	inode_dio_wait(inode);
> +
> +	/*
> +	 * Now that AIO and DIO has drained we can flush and (if necessary)
> +	 * invalidate the cached range over the first operation we are about to
> +	 * run. We include zero range here because it starts with a hole punch
> +	 * over the target range.
> +	 */
> +	switch (cmd) {
> +	case XFS_IOC_ZERO_RANGE:
> +	case XFS_IOC_UNRESVSP:
> +	case XFS_IOC_UNRESVSP64:
> +		error = xfs_flush_unmap_range(ip, bf->l_start, bf->l_len);
> +		if (error)
> +			goto out_unlock;
> +		break;
> +	}
> +
>  	switch (cmd) {
>  	case XFS_IOC_ZERO_RANGE:
>  		flags |= XFS_PREALLOC_SET;
> -- 
> 2.16.6
>