| Message ID | 20180412150826.20988-3-mszeredi@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Apr 12, 2018 at 05:07:53PM +0200, Miklos Szeredi wrote: > Currently opening an overlay file results in: > > - the real file on the underlying layer being opened > - f_path being set to the overlay {mount, dentry} pair > > This patch adds a new helper that allows the above to be explicitly > performed. I.e. it's the same as dentry_open(), except the underlying > inode to open is given as a separate argument. > > This is in preparation for stacking I/O operations on overlay files. > > Later, when implicit opening is removed, dentry_open() can be implemented > by just calling path_open(). > > Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> > --- > fs/open.c | 27 +++++++++++++++++++++++++++ > include/linux/fs.h | 2 ++ > 2 files changed, 29 insertions(+) > > diff --git a/fs/open.c b/fs/open.c > index 7ea118471dce..8c315f9ec2f6 100644 > --- a/fs/open.c > +++ b/fs/open.c > @@ -866,6 +866,33 @@ int vfs_open(const struct path *path, struct file *file, > return do_dentry_open(file, d_backing_inode(dentry), NULL, cred); > } > This really warrants some kernel-doc. Let me try to get this started and you can fix it: /** * path_open() - Open an inode by a particular name. * @path: The name of the file. * @flags: The O_ flags used to open this file. * @inode: The inode to open. * @cred: The task's credentials used when opening this file. * * ... * * Context: Process context. * Return: A pointer to a struct file or an IS_ERR pointer. Cannot return NULL. */ > +struct file *path_open(const struct path *path, int flags, struct inode *inode, > + const struct cred *cred) > +{ > + struct file *file; > + int retval; > + > + file = get_empty_filp(); > + if (!IS_ERR(file)) { > + file->f_flags = flags; > + file->f_path = *path; > + retval = do_dentry_open(file, inode, NULL, cred); > + if (retval) { > + put_filp(file); > + file = ERR_PTR(retval); > + } else { > + retval = open_check_o_direct(file); > + if (retval) { > + fput(file); > + file = ERR_PTR(retval); > + } > + } > + } > + > + return file; I'd find this clearer written like this ... + file = get_empty_filp(); + if (IS_ERR(file)) + return file; + + file->f_flags = flags; + file->f_path = *path; + retval = do_dentry_open(file, inode, NULL, cred); + if (retval) + goto err; + retval = open_check_o_direct(file); + if (retval) + goto err; + return file; +err: + put_filp(file); + return ERR_PTR(retval);
diff --git a/fs/open.c b/fs/open.c index 7ea118471dce..8c315f9ec2f6 100644 --- a/fs/open.c +++ b/fs/open.c @@ -866,6 +866,33 @@ int vfs_open(const struct path *path, struct file *file, return do_dentry_open(file, d_backing_inode(dentry), NULL, cred); } +struct file *path_open(const struct path *path, int flags, struct inode *inode, + const struct cred *cred) +{ + struct file *file; + int retval; + + file = get_empty_filp(); + if (!IS_ERR(file)) { + file->f_flags = flags; + file->f_path = *path; + retval = do_dentry_open(file, inode, NULL, cred); + if (retval) { + put_filp(file); + file = ERR_PTR(retval); + } else { + retval = open_check_o_direct(file); + if (retval) { + fput(file); + file = ERR_PTR(retval); + } + } + } + + return file; +} +EXPORT_SYMBOL(path_open); + struct file *dentry_open(const struct path *path, int flags, const struct cred *cred) { diff --git a/include/linux/fs.h b/include/linux/fs.h index f0f87f2beb79..c6d7e3b00163 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2401,6 +2401,8 @@ extern struct file *filp_open(const char *, int, umode_t); extern struct file *file_open_root(struct dentry *, struct vfsmount *, const char *, int, umode_t); extern struct file * dentry_open(const struct path *, int, const struct cred *); +extern struct file *path_open(const struct path *, int, struct inode *, + const struct cred *); extern int filp_close(struct file *, fl_owner_t id); extern struct filename *getname_flags(const char __user *, int, int *);
Currently opening an overlay file results in: - the real file on the underlying layer being opened - f_path being set to the overlay {mount, dentry} pair This patch adds a new helper that allows the above to be explicitly performed. I.e. it's the same as dentry_open(), except the underlying inode to open is given as a separate argument. This is in preparation for stacking I/O operations on overlay files. Later, when implicit opening is removed, dentry_open() can be implemented by just calling path_open(). Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> --- fs/open.c | 27 +++++++++++++++++++++++++++ include/linux/fs.h | 2 ++ 2 files changed, 29 insertions(+)