On Thu, Feb 25, 2016 at 11:36:48AM -0800, James Bottomley wrote:
> I need an API that allows me to obtain a clone of the current file
> pointer to pass in to an exec handler. I've labelled this as an
> internal API because I can't see how it would be useful outside of the
> fs subsystem. The use case will be a persistent binfmt_misc handler.
>
> Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> ---
> fs/internal.h | 1 +
> fs/open.c | 20 ++++++++++++++++++++
> 2 files changed, 21 insertions(+)
>
> diff --git a/fs/internal.h b/fs/internal.h
> index b71deee..c8ca0c9 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -108,6 +108,7 @@ extern long do_handle_open(int mountdirfd,
> struct file_handle __user *ufh, int open_flag);
> extern int open_check_o_direct(struct file *f);
> extern int vfs_open(const struct path *, struct file *, const struct cred *);
> +extern struct file *filp_clone_open(struct file *);
>
> /*
> * inode.c
> diff --git a/fs/open.c b/fs/open.c
> index 55bdc75..bb7ffd6 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -1004,6 +1004,26 @@ struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
> }
> EXPORT_SYMBOL(file_open_root);
>
> +struct file *filp_clone_open(struct file *oldfile)
> +{
> + struct file *file;
> + int retval;
> +
> + file = get_empty_filp();
> + if (IS_ERR(file))
> + return file;
> +
> + file->f_flags = oldfile->f_flags;
> + retval = vfs_open(&oldfile->f_path, file, oldfile->f_cred);
> + if (retval) {
> + fput(file);
You likely want put_file instead, although if I read it right this is
only cosmetics for consistency with dentry_open.
Also vast majority of the file uses 'error' instead of 'retval'. Any
reason to deviate here?
> + return ERR_PTR(retval);
> + }
> +
> + return file;
> +}
> +EXPORT_SYMBOL(filp_clone_open);
> +
> long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
> {
> struct open_flags op;
> --
> 2.6.2
>
--
Mateusz Guzik
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