Re: [PATCH 07/11] vfs: add nowait parameter for file_accessed()

[Christian Brauner]

On Sun, Aug 27, 2023 at 09:28:31PM +0800, Hao Xu wrote:
> From: Hao Xu <howeyxu@xxxxxxxxxxx>
> 
> Add a boolean parameter for file_accessed() to support nowait semantics.
> Currently it is true only with io_uring as its initial caller.
> 
> Signed-off-by: Hao Xu <howeyxu@xxxxxxxxxxx>
> ---
>  arch/s390/hypfs/inode.c | 2 +-
>  block/fops.c            | 2 +-
>  fs/btrfs/file.c         | 2 +-
>  fs/btrfs/inode.c        | 2 +-
>  fs/coda/dir.c           | 4 ++--
>  fs/ext2/file.c          | 4 ++--
>  fs/ext4/file.c          | 6 +++---
>  fs/f2fs/file.c          | 4 ++--
>  fs/fuse/dax.c           | 2 +-
>  fs/fuse/file.c          | 4 ++--
>  fs/gfs2/file.c          | 2 +-
>  fs/hugetlbfs/inode.c    | 2 +-
>  fs/nilfs2/file.c        | 2 +-
>  fs/orangefs/file.c      | 2 +-
>  fs/orangefs/inode.c     | 2 +-
>  fs/pipe.c               | 2 +-
>  fs/ramfs/file-nommu.c   | 2 +-
>  fs/readdir.c            | 2 +-
>  fs/smb/client/cifsfs.c  | 2 +-
>  fs/splice.c             | 2 +-
>  fs/ubifs/file.c         | 2 +-
>  fs/udf/file.c           | 2 +-
>  fs/xfs/xfs_file.c       | 6 +++---
>  fs/zonefs/file.c        | 4 ++--
>  include/linux/fs.h      | 5 +++--
>  mm/filemap.c            | 8 ++++----
>  mm/shmem.c              | 6 +++---
>  27 files changed, 43 insertions(+), 42 deletions(-)
> 
> diff --git a/arch/s390/hypfs/inode.c b/arch/s390/hypfs/inode.c
> index ee919bfc8186..55f562027c4f 100644
> --- a/arch/s390/hypfs/inode.c
> +++ b/arch/s390/hypfs/inode.c
> @@ -157,7 +157,7 @@ static ssize_t hypfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
>  	if (!count)
>  		return -EFAULT;
>  	iocb->ki_pos = pos + count;
> -	file_accessed(file);
> +	file_accessed(file, false);

Why? If all you do is skip atime update anyway then just add something
like:

bool file_needs_atime(struct file *file)
{
       return !(file->f_flags & O_NOATIME) &&
              atime_needs_update(&file->f_path, d_inode(path->dentry));
}

and then

if (file_needs_atime(file) && IOURING_WANTS_ASYNC)
	return -EAGAIN;

instead of touching all this code.