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/affs/file.c b/fs/affs/file.c
index 659c579..0548c53 100644
--- a/fs/affs/file.c
+++ b/fs/affs/file.c
@@ -33,11 +33,11 @@
 		 inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
 
 	if (atomic_dec_and_test(&AFFS_I(inode)->i_opencnt)) {
-		mutex_lock(&inode->i_mutex);
+		inode_lock(inode);
 		if (inode->i_size != AFFS_I(inode)->mmu_private)
 			affs_truncate(inode);
 		affs_free_prealloc(inode);
-		mutex_unlock(&inode->i_mutex);
+		inode_unlock(inode);
 	}
 
 	return 0;
@@ -958,12 +958,12 @@
 	if (err)
 		return err;
 
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 	ret = write_inode_now(inode, 0);
 	err = sync_blockdev(inode->i_sb->s_bdev);
 	if (!ret)
 		ret = err;
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	return ret;
 }
 const struct file_operations affs_file_operations = {