vfs: add flags to d_real()

Add a separate flags argument (in addition to the open flags) to control
the behavior of d_real().
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Documentation/filesystems/Locking

@@ -22,7 +22,7 @@ prototypes:
 	struct vfsmount *(*d_automount)(struct path *path);
 	int (*d_manage)(const struct path *, bool);
 	struct dentry *(*d_real)(struct dentry *, const struct inode *,
-				 unsigned int);
+				 unsigned int, unsigned int);
 
 locking rules:
 		rename_lock	->d_lock	may block	rcu-walk

Documentation/filesystems/vfs.txt

@@ -990,7 +990,7 @@ struct dentry_operations {
 	struct vfsmount *(*d_automount)(struct path *);
 	int (*d_manage)(const struct path *, bool);
 	struct dentry *(*d_real)(struct dentry *, const struct inode *,
-				 unsigned int);
+				 unsigned int, unsigned int);
 };
 
   d_revalidate: called when the VFS needs to revalidate a dentry. This

fs/open.c

@@ -96,7 +96,7 @@ long vfs_truncate(const struct path *path, loff_t length)
 	 * write access on the upper inode, not on the overlay inode.  For
 	 * non-overlay filesystems d_real() is an identity function.
 	 */
-	upperdentry = d_real(path->dentry, NULL, O_WRONLY);
+	upperdentry = d_real(path->dentry, NULL, O_WRONLY, 0);
 	error = PTR_ERR(upperdentry);
 	if (IS_ERR(upperdentry))
 		goto mnt_drop_write_and_out;
@@ -857,7 +857,7 @@ EXPORT_SYMBOL(file_path);
 int vfs_open(const struct path *path, struct file *file,
 	     const struct cred *cred)
 {
-	struct dentry *dentry = d_real(path->dentry, NULL, file->f_flags);
+	struct dentry *dentry = d_real(path->dentry, NULL, file->f_flags, 0);
 
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);

fs/overlayfs/super.c

@@ -70,7 +70,7 @@ static int ovl_check_append_only(struct inode *inode, int flag)
 
 static struct dentry *ovl_d_real(struct dentry *dentry,
 				 const struct inode *inode,
-				 unsigned int open_flags)
+				 unsigned int open_flags, unsigned int flags)
 {
 	struct dentry *real;
 	int err;
@@ -102,7 +102,7 @@ static struct dentry *ovl_d_real(struct dentry *dentry,
 		goto bug;
 
 	/* Handle recursion */
-	real = d_real(real, inode, open_flags);
+	real = d_real(real, inode, open_flags, 0);
 
 	if (!inode || inode == d_inode(real))
 		return real;

include/linux/dcache.h

@@ -147,7 +147,7 @@ struct dentry_operations {
 	struct vfsmount *(*d_automount)(struct path *);
 	int (*d_manage)(const struct path *, bool);
 	struct dentry *(*d_real)(struct dentry *, const struct inode *,
-				 unsigned int);
+				 unsigned int, unsigned int);
 } ____cacheline_aligned;
 
 /*
@@ -566,7 +566,8 @@ static inline struct dentry *d_backing_dentry(struct dentry *upper)
  * d_real - Return the real dentry
  * @dentry: the dentry to query
  * @inode: inode to select the dentry from multiple layers (can be NULL)
- * @flags: open flags to control copy-up behavior
+ * @open_flags: open flags to control copy-up behavior
+ * @flags: flags to control what is returned by this function
  *
  * If dentry is on a union/overlay, then return the underlying, real dentry.
  * Otherwise return the dentry itself.
@@ -575,10 +576,10 @@ static inline struct dentry *d_backing_dentry(struct dentry *upper)
  */
 static inline struct dentry *d_real(struct dentry *dentry,
 				    const struct inode *inode,
-				    unsigned int flags)
+				    unsigned int open_flags, unsigned int flags)
 {
 	if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
-		return dentry->d_op->d_real(dentry, inode, flags);
+		return dentry->d_op->d_real(dentry, inode, open_flags, flags);
 	else
 		return dentry;
 }
@@ -593,7 +594,7 @@ static inline struct dentry *d_real(struct dentry *dentry,
 static inline struct inode *d_real_inode(const struct dentry *dentry)
 {
 	/* This usage of d_real() results in const dentry */
-	return d_backing_inode(d_real((struct dentry *) dentry, NULL, 0));
+	return d_backing_inode(d_real((struct dentry *) dentry, NULL, 0, 0));
 }
 
 struct name_snapshot {

include/linux/fs.h

@@ -1233,7 +1233,7 @@ static inline struct inode *file_inode(const struct file *f)
 
 static inline struct dentry *file_dentry(const struct file *file)
 {
-	return d_real(file->f_path.dentry, file_inode(file), 0);
+	return d_real(file->f_path.dentry, file_inode(file), 0, 0);
 }
 
 static inline int locks_lock_file_wait(struct file *filp, struct file_lock *fl)