[PATCH 2/7] f2fs: read summary blocks with the correct amount for migration_granularity

[Daeho Jeong <daeho43@gmail.com>]

From: Daeho Jeong <daehojeong@google.com>

Now we do readahead for a full section by not considering
migration_granularity and it triggers unnecessary read. So, make it read
with the correct amount.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---
 fs/f2fs/gc.c | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 46e3bc26b78a..b5d3fd40b17a 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -1708,24 +1708,33 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
 	struct blk_plug plug;
 	unsigned int segno = start_segno;
 	unsigned int end_segno = start_segno + SEGS_PER_SEC(sbi);
+	unsigned int sec_end_segno;
 	int seg_freed = 0, migrated = 0;
 	unsigned char type = IS_DATASEG(get_seg_entry(sbi, segno)->type) ?
 						SUM_TYPE_DATA : SUM_TYPE_NODE;
 	unsigned char data_type = (type == SUM_TYPE_DATA) ? DATA : NODE;
 	int submitted = 0;
 
-	if (__is_large_section(sbi))
-		end_segno = rounddown(end_segno, SEGS_PER_SEC(sbi));
+	if (__is_large_section(sbi)) {
+		sec_end_segno = rounddown(end_segno, SEGS_PER_SEC(sbi));
 
-	/*
-	 * zone-capacity can be less than zone-size in zoned devices,
-	 * resulting in less than expected usable segments in the zone,
-	 * calculate the end segno in the zone which can be garbage collected
-	 */
-	if (f2fs_sb_has_blkzoned(sbi))
-		end_segno -= SEGS_PER_SEC(sbi) -
+		/*
+		 * zone-capacity can be less than zone-size in zoned devices,
+		 * resulting in less than expected usable segments in the zone,
+		 * calculate the end segno in the zone which can be garbage
+		 * collected
+		 */
+		if (f2fs_sb_has_blkzoned(sbi))
+			sec_end_segno -= SEGS_PER_SEC(sbi) -
 					f2fs_usable_segs_in_sec(sbi, segno);
 
+		if (gc_type == BG_GC)
+			end_segno = start_segno + sbi->migration_granularity;
+
+		if (end_segno > sec_end_segno)
+			end_segno = sec_end_segno;
+	}
+
 	sanity_check_seg_type(sbi, get_seg_entry(sbi, segno)->type);
 
 	/* readahead multi ssa blocks those have contiguous address */
@@ -1762,9 +1771,6 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
 
 		if (get_valid_blocks(sbi, segno, false) == 0)
 			goto freed;
-		if (gc_type == BG_GC && __is_large_section(sbi) &&
-				migrated >= sbi->migration_granularity)
-			goto skip;
 		if (!PageUptodate(sum_page) || unlikely(f2fs_cp_error(sbi)))
 			goto skip;
 
@@ -1803,7 +1809,8 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
 
 		if (__is_large_section(sbi))
 			sbi->next_victim_seg[gc_type] =
-				(segno + 1 < end_segno) ? segno + 1 : NULL_SEGNO;
+				(segno + 1 < sec_end_segno) ?
+					segno + 1 : NULL_SEGNO;
 skip:
 		f2fs_put_page(sum_page, 0);
 	}
-- 
2.46.0.469.g59c65b2a67-goog