wrappers for ->i_mutex access

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/open.c b/fs/open.c
index b25b154..55bdc75 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -58,10 +58,10 @@
 	if (ret)
 		newattrs.ia_valid |= ret | ATTR_FORCE;
 
-	mutex_lock(&dentry->d_inode->i_mutex);
+	inode_lock(dentry->d_inode);
 	/* Note any delegations or leases have already been broken: */
 	ret = notify_change(dentry, &newattrs, NULL);
-	mutex_unlock(&dentry->d_inode->i_mutex);
+	inode_unlock(dentry->d_inode);
 	return ret;
 }
 
@@ -510,7 +510,7 @@
 	if (error)
 		return error;
 retry_deleg:
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 	error = security_path_chmod(path, mode);
 	if (error)
 		goto out_unlock;
@@ -518,7 +518,7 @@
 	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 	error = notify_change(path->dentry, &newattrs, &delegated_inode);
 out_unlock:
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	if (delegated_inode) {
 		error = break_deleg_wait(&delegated_inode);
 		if (!error)
@@ -593,11 +593,11 @@
 	if (!S_ISDIR(inode->i_mode))
 		newattrs.ia_valid |=
 			ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 	error = security_path_chown(path, uid, gid);
 	if (!error)
 		error = notify_change(path->dentry, &newattrs, &delegated_inode);
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	if (delegated_inode) {
 		error = break_deleg_wait(&delegated_inode);
 		if (!error)