vfs: add helpers to get root and pwd

Add three helpers that retrieve a refcounted copy of the root and cwd
from the supplied fs_struct.

 get_fs_root()
 get_fs_pwd()
 get_fs_root_and_pwd()

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 27 insertions, 0 deletions

diff --git a/include/linux/fs_struct.h b/include/linux/fs_struct.h
index 78a05bfcd8e..eca3d520213 100644
--- a/include/linux/fs_struct.h
+++ b/include/linux/fs_struct.h
@@ -21,4 +21,31 @@ extern void free_fs_struct(struct fs_struct *);
 extern void daemonize_fs_struct(void);
 extern int unshare_fs_struct(void);
 
+static inline void get_fs_root(struct fs_struct *fs, struct path *root)
+{
+	read_lock(&fs->lock);
+	*root = fs->root;
+	path_get(root);
+	read_unlock(&fs->lock);
+}
+
+static inline void get_fs_pwd(struct fs_struct *fs, struct path *pwd)
+{
+	read_lock(&fs->lock);
+	*pwd = fs->pwd;
+	path_get(pwd);
+	read_unlock(&fs->lock);
+}
+
+static inline void get_fs_root_and_pwd(struct fs_struct *fs, struct path *root,
+				       struct path *pwd)
+{
+	read_lock(&fs->lock);
+	*root = fs->root;
+	path_get(root);
+	*pwd = fs->pwd;
+	path_get(pwd);
+	read_unlock(&fs->lock);
+}
+
 #endif /* _LINUX_FS_STRUCT_H */