From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mateusz Guzik Subject: Re: [Patch v2 1/3] fs: add filp_clone_open API Date: Tue, 8 Mar 2016 10:17:07 +0100 Message-ID: <20160308091705.GB2189@mguzik> References: <1456428890.2377.2.camel@HansenPartnership.com> <1456429008.2377.4.camel@HansenPartnership.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1456429008.2377.4.camel-d9PhHud1JfjCXq6kfMZ53/egYHeGw8Jk@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: James Bottomley Cc: linux-fsdevel , containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Al Viro List-Id: containers.vger.kernel.org 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 > --- > 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:46932 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932383AbcCHJRP (ORCPT ); Tue, 8 Mar 2016 04:17:15 -0500 Date: Tue, 8 Mar 2016 10:17:07 +0100 From: Mateusz Guzik To: James Bottomley Cc: containers@lists.linux-foundation.org, linux-fsdevel , Al Viro Subject: Re: [Patch v2 1/3] fs: add filp_clone_open API Message-ID: <20160308091705.GB2189@mguzik> References: <1456428890.2377.2.camel@HansenPartnership.com> <1456429008.2377.4.camel@HansenPartnership.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1456429008.2377.4.camel@HansenPartnership.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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 > --- > 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