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SubjectRe: [PATCH] docuement filesystem helpers for custom 'struct file's
On Wed, 19 Sep 2007 10:47:23 -0700 Dave Hansen wrote:

> On Wed, 2007-09-19 at 18:26 +0100, Christoph Hellwig wrote:
> > On Mon, Sep 17, 2007 at 11:27:18AM -0700, Dave Hansen wrote:
> > >
> > > Christoph H. says this stands on its own and can go in before the
> > > rest of the r/o bind mount set.
> > >
> > > ---
> > >
> > > Some filesystems forego the vfs and may_open() and create their
> > > own 'struct file's.
> > >
> > > This patch creates a couple of helper functions which can be
> > > used by these filesystems, and will provide a unified place
> > > which the r/o bind mount code may patch.
> > >
> > > Also, rename an existing, static-scope init_file() to a less
> > > generic name.
> >
> > Looks good. But please provide a patch ontop of your patchkit to
> > add kernel-doc comments for the two new exported functions.
>
> Appended. I started to write the comments to describe the function
> arguments, but they all looked pretty retarded.

Hi Dave,

They aren't quite in kernel-doc format. Holler if you need help
with that, or see examples, or
Documentation/kernel-doc-nano-HOWTO.txt.

> > Are there any direct caller of get_empty_filp left after this patch?
> > We really should get rid of that export to stop people from shooting
> > themselves in the foot.
>
> Yeah, there are a few left. But, they're in the middle of what is
> sometimes tricky error handling, so I think we should trickle those in
> later.
>
>
> -- Dave
>
> lxc-dave/fs/file_table.c | 22 +++++++++++++++++++++-
> 1 file changed, 21 insertions(+), 1 deletion(-)
>
> diff -puN fs/file_table.c~document fs/file_table.c
> --- lxc/fs/file_table.c~document 2007-09-19 10:31:13.000000000 -0700
> +++ lxc-dave/fs/file_table.c 2007-09-19 10:39:34.000000000 -0700
> @@ -137,6 +137,18 @@ fail:
>
> EXPORT_SYMBOL(get_empty_filp);
>
> +/**
> + * alloc_file - allocate and initialize a 'struct file' with
> + * the given arguments

* function_name - short description (on one line)
* @param1: descr1
* @param2: descr2
etc.

> + *
> + * Use this instead of get_empty_filp() to get a new
> + * 'struct file'. Do so because of the same initialization
> + * pitfalls reasons listed for init_file(). This is a
> + * preferred interface to using init_file().
> + *
> + * If all the callers of init_file() are eliminated, its
> + * code should be moved into this function.
> + */
> struct file *alloc_file(struct vfsmount *mnt, struct dentry *dentry,
> mode_t mode, const struct file_operations *fop)
> {
> @@ -152,7 +164,15 @@ struct file *alloc_file(struct vfsmount
> }
> EXPORT_SYMBOL(alloc_file);
>
> -/*
> +/**
> + * init_file - initialize a 'struct file'
> + * @file: the already allocated 'struct file' to initialized
> + * @mnt: the vfsmount on which the file resides
> + *
> + * Use this instead of setting the members directly. Doing so
> + * avoids making mistakes like forgetting the mntget() or
> + * forgetting to take a write on the mnt.
> + *
> * Note: This is a crappy interface. It is here to make
> * merging with the existing users of get_empty_filp()
> * who have complex failure logic easier. All users

OK, that one looks better. :)

---
~Randy
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