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/reiserfs/file.c b/fs/reiserfs/file.c
index 96a1bcf..9424a4b 100644
--- a/fs/reiserfs/file.c
+++ b/fs/reiserfs/file.c
@@ -158,7 +158,7 @@
 	if (err)
 		return err;
 
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 	BUG_ON(!S_ISREG(inode->i_mode));
 	err = sync_mapping_buffers(inode->i_mapping);
 	reiserfs_write_lock(inode->i_sb);
@@ -166,7 +166,7 @@
 	reiserfs_write_unlock(inode->i_sb);
 	if (barrier_done != 1 && reiserfs_barrier_flush(inode->i_sb))
 		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	if (barrier_done < 0)
 		return barrier_done;
 	return (err < 0) ? -EIO : 0;