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/cifs/file.c b/fs/cifs/file.c
index 0a2752b..ff882ae 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2267,7 +2267,7 @@
 	rc = filemap_write_and_wait_range(inode->i_mapping, start, end);
 	if (rc)
 		return rc;
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 
 	xid = get_xid();
 
@@ -2292,7 +2292,7 @@
 	}
 
 	free_xid(xid);
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	return rc;
 }
 
@@ -2309,7 +2309,7 @@
 	rc = filemap_write_and_wait_range(inode->i_mapping, start, end);
 	if (rc)
 		return rc;
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 
 	xid = get_xid();
 
@@ -2326,7 +2326,7 @@
 	}
 
 	free_xid(xid);
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	return rc;
 }
 
@@ -2672,7 +2672,7 @@
 	 * with a brlock that prevents writing.
 	 */
 	down_read(&cinode->lock_sem);
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 
 	rc = generic_write_checks(iocb, from);
 	if (rc <= 0)
@@ -2685,7 +2685,7 @@
 	else
 		rc = -EACCES;
 out:
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 
 	if (rc > 0) {
 		ssize_t err = generic_write_sync(file, iocb->ki_pos - rc, rc);