vfs: add vfs_get_link() helper

This helper is for filesystems that want to read the symlink and are better
off with the get_link() interface (returning a char *) rather than the
readlink() interface (copy into a userspace buffer).

Also call the LSM hook for readlink (not get_link) since this is for
symlink reading not following.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 901e25d..bc8ac51 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2919,6 +2919,7 @@
 extern int vfs_lstat(const char __user *, struct kstat *);
 extern int vfs_fstat(unsigned int, struct kstat *);
 extern int vfs_fstatat(int , const char __user *, struct kstat *, int);
+extern const char *vfs_get_link(struct dentry *, struct delayed_call *);
 
 extern int __generic_block_fiemap(struct inode *inode,
 				  struct fiemap_extent_info *fieinfo,