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    Subject[PATCH] docuement filesystem helpers for custom 'struct file's
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    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.

    > 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
    + *
    + * 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
    _

    -
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