f2fs: keep meta pages in cp_error state

It turns out losing meta pages in shutdown period makes f2fs very unstable
so that I could see many unexpected error conditions.

Let's keep meta pages for fault injection and sudden power-off tests.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/checkpoint.c

@@ -242,11 +242,8 @@ static int __f2fs_write_meta_page(struct page *page,
 
 	trace_f2fs_writepage(page, META);
 
-	if (unlikely(f2fs_cp_error(sbi))) {
-		dec_page_count(sbi, F2FS_DIRTY_META);
-		unlock_page(page);
-		return 0;
-	}
+	if (unlikely(f2fs_cp_error(sbi)))
+		goto redirty_out;
 	if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
 		goto redirty_out;
 	if (wbc->for_reclaim && page->index < GET_SUM_BLOCK(sbi, 0))
@@ -1129,6 +1126,9 @@ static void wait_on_all_pages_writeback(struct f2fs_sb_info *sbi)
 		if (!get_pages(sbi, F2FS_WB_CP_DATA))
 			break;
 
+		if (unlikely(f2fs_cp_error(sbi)))
+			break;
+
 		io_schedule_timeout(5*HZ);
 	}
 	finish_wait(&sbi->cp_wait, &wait);
@@ -1202,8 +1202,12 @@ static void commit_checkpoint(struct f2fs_sb_info *sbi,
 
 	/* writeout cp pack 2 page */
 	err = __f2fs_write_meta_page(page, &wbc, FS_CP_META_IO);
-	f2fs_bug_on(sbi, err);
+	if (unlikely(err && f2fs_cp_error(sbi))) {
+		f2fs_put_page(page, 1);
+		return;
+	}
 
+	f2fs_bug_on(sbi, err);
 	f2fs_put_page(page, 0);
 
 	/* submit checkpoint (with barrier if NOBARRIER is not set) */
@@ -1229,7 +1233,7 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 	while (get_pages(sbi, F2FS_DIRTY_META)) {
 		f2fs_sync_meta_pages(sbi, META, LONG_MAX, FS_CP_META_IO);
 		if (unlikely(f2fs_cp_error(sbi)))
-			return -EIO;
+			break;
 	}
 
 	/*
@@ -1309,7 +1313,7 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 			f2fs_sync_meta_pages(sbi, META, LONG_MAX,
 							FS_CP_META_IO);
 			if (unlikely(f2fs_cp_error(sbi)))
-				return -EIO;
+				break;
 		}
 	}
 
@@ -1350,9 +1354,6 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 	/* wait for previous submitted meta pages writeback */
 	wait_on_all_pages_writeback(sbi);
 
-	if (unlikely(f2fs_cp_error(sbi)))
-		return -EIO;
-
 	/* flush all device cache */
 	err = f2fs_flush_device_cache(sbi);
 	if (err)
@@ -1364,9 +1365,6 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 
 	f2fs_release_ino_entry(sbi, false);
 
-	if (unlikely(f2fs_cp_error(sbi)))
-		return -EIO;
-
 	clear_sbi_flag(sbi, SBI_IS_DIRTY);
 	clear_sbi_flag(sbi, SBI_NEED_CP);
 	__set_cp_next_pack(sbi);
@@ -1381,7 +1379,7 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 
 	f2fs_bug_on(sbi, get_pages(sbi, F2FS_DIRTY_DENTS));
 
-	return 0;
+	return unlikely(f2fs_cp_error(sbi)) ? -EIO : 0;
 }
 
 /*