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

Darrick J. Wong
2024-06-20T18:57:13Z

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
>
>