coda: fix nlink updates for directories

The Coda client sets the directory link count to 1 when it isn't sure how many
subdirectories we have.  In this case we shouldn't change the link count in
the kernel when a subdirectory is created or removed.
Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/coda/dir.c

@@ -173,12 +173,11 @@ int coda_permission(struct inode *inode, int mask, struct nameidata *nd)
 
  out:
 	unlock_kernel();
-
 	return error;
 }
 
 
-static inline void coda_dir_changed(struct inode *dir, int link)
+static inline void coda_dir_update_mtime(struct inode *dir)
 {
 #ifdef REQUERY_VENUS_FOR_MTIME
 	/* invalidate the directory cnode's attributes so we refetch the
@@ -190,8 +189,23 @@ static inline void coda_dir_changed(struct inode *dir, int link)
 	 * right most of the time. Note: we only do this for directories. */
 	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
 #endif
-	if (link)
-		dir->i_nlink += link;
+}
+
+/* we have to wrap inc_nlink/drop_nlink because sometimes userspace uses a
+ * trick to fool GNU find's optimizations. If we can't be sure of the link
+ * (because of volume mount points) we set i_nlink to 1 which forces find
+ * to consider every child as a possible directory. We should also never
+ * see an increment or decrement for deleted directories where i_nlink == 0 */
+static inline void coda_dir_inc_nlink(struct inode *dir)
+{
+	if (dir->i_nlink >= 2)
+		inc_nlink(dir);
+}
+
+static inline void coda_dir_drop_nlink(struct inode *dir)
+{
+	if (dir->i_nlink > 2)
+		drop_nlink(dir);
 }
 
 /* creation routines: create, mknod, mkdir, link, symlink */
@@ -229,7 +243,7 @@ static int coda_create(struct inode *dir, struct dentry *de, int mode, struct na
 	}
 
 	/* invalidate the directory cnode's attributes */
-	coda_dir_changed(dir, 0);
+	coda_dir_update_mtime(dir);
 	unlock_kernel();
 	d_instantiate(de, inode);
 	return 0;
@@ -270,7 +284,8 @@ static int coda_mkdir(struct inode *dir, struct dentry *de, int mode)
 	}
 
 	/* invalidate the directory cnode's attributes */
-	coda_dir_changed(dir, 1);
+	coda_dir_inc_nlink(dir);
+	coda_dir_update_mtime(dir);
 	unlock_kernel();
 	d_instantiate(de, inode);
 	return 0;
@@ -301,7 +316,7 @@ static int coda_link(struct dentry *source_de, struct inode *dir_inode,
 		goto out;
 	}
 
-	coda_dir_changed(dir_inode, 0);
+	coda_dir_update_mtime(dir_inode);
 	atomic_inc(&inode->i_count);
 	d_instantiate(de, inode);
 	inc_nlink(inode);
@@ -344,7 +359,7 @@ static int coda_symlink(struct inode *dir_inode, struct dentry *de,
 
 	/* mtime is no good anymore */
 	if ( !error )
-		coda_dir_changed(dir_inode, 0);
+		coda_dir_update_mtime(dir_inode);
 
 	unlock_kernel();
 	return error;
@@ -366,10 +381,9 @@ int coda_unlink(struct inode *dir, struct dentry *de)
 		return error;
 	}
 
-	coda_dir_changed(dir, 0);
+	coda_dir_update_mtime(dir);
 	drop_nlink(de->d_inode);
 	unlock_kernel();
-
 	return 0;
 }
 
@@ -393,11 +407,11 @@ int coda_rmdir(struct inode *dir, struct dentry *de)
 		return error;
 	}
 
-	coda_dir_changed(dir, -1);
+	coda_dir_drop_nlink(dir);
+	coda_dir_update_mtime(dir);
 	drop_nlink(de->d_inode);
 	d_delete(de);
 	unlock_kernel();
-
 	return 0;
 }
 
@@ -409,7 +423,6 @@ static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,
 	const char *new_name = new_dentry->d_name.name;
 	int old_length = old_dentry->d_name.len;
 	int new_length = new_dentry->d_name.len;
-        int link_adjust = 0;
 	int error;
 
 	lock_kernel();
@@ -421,11 +434,12 @@ static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,
 
 	if ( !error ) {
 		if ( new_dentry->d_inode ) {
-			if ( S_ISDIR(new_dentry->d_inode->i_mode) )
-                        	link_adjust = 1;
-
-                        coda_dir_changed(old_dir, -link_adjust);
-                        coda_dir_changed(new_dir,  link_adjust);
+			if ( S_ISDIR(new_dentry->d_inode->i_mode) ) {
+				coda_dir_drop_nlink(old_dir);
+				coda_dir_inc_nlink(new_dir);
+			}
+			coda_dir_update_mtime(old_dir);
+			coda_dir_update_mtime(new_dir);
 			coda_flag_inode(new_dentry->d_inode, C_VATTR);
 		} else {
 			coda_flag_inode(old_dir, C_VATTR);