Commit 4aa7c634 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

vfs: add i_op->dentry_open() 



Add a new inode operation i_op->dentry_open().  This is for stacked filesystems
that want to return a struct file from a different filesystem.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
parent f114040e

Documentation/filesystems/Locking

+2 −0
Original line number Diff line number Diff line
@@ -67,6 +67,7 @@ prototypes: 
				struct file *, unsigned open_flag,

				umode_t create_mode, int *opened);

	int (*tmpfile) (struct inode *, struct dentry *, umode_t);

	int (*dentry_open)(struct dentry *, struct file *, const struct cred *);



locking rules:

	all may block
@@ -96,6 +97,7 @@ fiemap: no 
update_time:	no

atomic_open:	yes

tmpfile:	no

dentry_open:	no



	Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on

victim.

Documentation/filesystems/vfs.txt

+7 −0
Original line number Diff line number Diff line
@@ -364,6 +364,7 @@ struct inode_operations { 
	int (*atomic_open)(struct inode *, struct dentry *, struct file *,

			unsigned open_flag, umode_t create_mode, int *opened);

	int (*tmpfile) (struct inode *, struct dentry *, umode_t);

	int (*dentry_open)(struct dentry *, struct file *, const struct cred *);

};



Again, all methods are called without any locks being held, unless
@@ -696,6 +697,12 @@ struct address_space_operations { 
  	but instead uses bmap to find out where the blocks in the file

  	are and uses those addresses directly.



  dentry_open: *WARNING: probably going away soon, do not use!* This is an

	alternative to f_op->open(), the difference is that this method may open

	a file not necessarily originating from the same filesystem as the one

	i_op->open() was called on.  It may be useful for stacking filesystems

	which want to allow native I/O directly on underlying files.





  invalidatepage: If a page has PagePrivate set, then invalidatepage

        will be called when part or all of the page is to be removed

fs/namei.c

+6 −3
Original line number Diff line number Diff line
@@ -3064,9 +3064,12 @@ static int do_last(struct nameidata *nd, struct path *path, 
	error = may_open(&nd->path, acc_mode, open_flag);

	if (error)

		goto out;

	file->f_path.mnt = nd->path.mnt;

	error = finish_open(file, nd->path.dentry, NULL, opened);

	if (error) {



	BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */

	error = vfs_open(&nd->path, file, current_cred());

	if (!error) {

		*opened |= FILE_OPENED;

	} else {

		if (error == -EOPENSTALE)

			goto stale_open;

		goto out;

fs/open.c

+21 −2
Original line number Diff line number Diff line
@@ -823,8 +823,7 @@ struct file *dentry_open(const struct path *path, int flags, 
	f = get_empty_filp();

	if (!IS_ERR(f)) {

		f->f_flags = flags;

		f->f_path = *path;

		error = do_dentry_open(f, NULL, cred);

		error = vfs_open(path, f, cred);

		if (!error) {

			/* from now on we need fput() to dispose of f */

			error = open_check_o_direct(f);
@@ -841,6 +840,26 @@ struct file *dentry_open(const struct path *path, int flags, 
}

EXPORT_SYMBOL(dentry_open);



/**

 * vfs_open - open the file at the given path

 * @path: path to open

 * @filp: newly allocated file with f_flag initialized

 * @cred: credentials to use

 */

int vfs_open(const struct path *path, struct file *filp,

	     const struct cred *cred)

{

	struct inode *inode = path->dentry->d_inode;



	if (inode->i_op->dentry_open)

		return inode->i_op->dentry_open(path->dentry, filp, cred);

	else {

		filp->f_path = *path;

		return do_dentry_open(filp, NULL, cred);

	}

}

EXPORT_SYMBOL(vfs_open);



static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)

{

	int lookup_flags = 0;

include/linux/fs.h

+4 −0
Original line number Diff line number Diff line
@@ -1528,6 +1528,9 @@ struct inode_operations { 
			   umode_t create_mode, int *opened);

	int (*tmpfile) (struct inode *, struct dentry *, umode_t);

	int (*set_acl)(struct inode *, struct posix_acl *, int);



	/* WARNING: probably going away soon, do not use! */

	int (*dentry_open)(struct dentry *, struct file *, const struct cred *);

} ____cacheline_aligned;



ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
@@ -2040,6 +2043,7 @@ extern struct file *file_open_name(struct filename *, int, umode_t); 
extern struct file *filp_open(const char *, int, umode_t);

extern struct file *file_open_root(struct dentry *, struct vfsmount *,

				   const char *, int);

extern int vfs_open(const struct path *, struct file *, const struct cred *);

extern struct file * dentry_open(const struct path *, int, const struct cred *);

extern int filp_close(struct file *, fl_owner_t id);