nilfs2: fix missing cleanup of gc cache on error cases

This fixes an -rc1 regression brought by the commit:
1cf58fa840472ec7df6bf2312885949ebb308853 ("nilfs2: shorten freeze
period due to GC in write operation v3").

Although the patch moved out a function call of
nilfs_ioctl_move_blocks() to nilfs_ioctl_clean_segments() from
nilfs_ioctl_prepare_clean_segments(), it didn't move corresponding
cleanup job needed for the error case.

This will move the missing cleanup job to the destination function.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: Jiro SEKIBA <jir@unicus.jp>

fs/nilfs2/ioctl.c

@@ -467,7 +467,6 @@ int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs,
 	return 0;
 
  failed:
-	nilfs_remove_all_gcinode(nilfs);
 	printk(KERN_ERR "NILFS: GC failed during preparation: %s: err=%d\n",
 	       msg, ret);
 	return ret;
@@ -556,6 +555,8 @@ static int nilfs_ioctl_clean_segments(struct inode *inode, struct file *filp,
 	else
 		ret = nilfs_clean_segments(inode->i_sb, argv, kbufs);
 
+	if (ret < 0)
+		nilfs_remove_all_gcinode(nilfs);
 	clear_nilfs_gc_running(nilfs);
 
  out_free: