# Re: \[RFC PATCH 1/2\] fs: Add dirreadahead syscall and VFS hooks

- From: Dave Chinner \<hidden\>
- Date: 2014-07-31 03:31:56 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2014/07/86635
- Thread: https://ratatoskr.run/linux-api/2014/07/86635/t.md

```text
On Tue, Jul 29, 2014 at 10:21:50AM +0200, Michael Kerrisk wrote:
> [CC+=linux-api]
> 
> On Fri, Jul 25, 2014 at 7:37 PM, Abhi Das [ref] wrote:
> > Also adds a void *opaque field to struct dir_context that can be
> > used by filesystems to temporarily store any context as this
> > struct gets passed around in the fs.

So the prototype is:

int dir_readahead(int fd, off64_t offset, unsigned int count);

Why do we need a new syscall for this?

$ man 2 readahead
....
ssize_t readahead(int fd, off64_t offset, size_t count);
....
	EINVAL fd does not refer to a file type to which readahead() can be applied.


Cheers,

Dave.
-- 
Dave Chinner
david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org
```