f2fs: increase BG GC migration window granularity when boosted for zoned devices

BugLink: https://bugs.launchpad.net/bugs/2089884

[ Upstream commit 2223fe652f759649ae1d520e47e5f06727c0acbd ]

Need bigger BG GC migration window granularity when free section is
running low.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Stable-dep-of: 5cc69a27abfa ("f2fs: forcibly migrate to secure space for zoned device file pinning")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>

fs/f2fs/gc.c

@@ -1725,10 +1725,18 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
 			sec_end_segno -= SEGS_PER_SEC(sbi) -
 					f2fs_usable_segs_in_sec(sbi, segno);
 
-		if (gc_type == BG_GC)
-			end_segno = start_segno +
+		if (gc_type == BG_GC) {
+			unsigned int window_granularity =
 				sbi->migration_window_granularity;
 
+			if (f2fs_sb_has_blkzoned(sbi) &&
+					!has_enough_free_blocks(sbi,
+					LIMIT_BOOST_ZONED_GC))
+				window_granularity *= BOOST_GC_MULTIPLE;
+
+			end_segno = start_segno + window_granularity;
+		}
+
 		if (end_segno > sec_end_segno)
 			end_segno = sec_end_segno;
 	}

fs/f2fs/gc.h

@@ -33,6 +33,7 @@
 #define LIMIT_NO_ZONED_GC	60 /* percentage over total user space of no gc for zoned devices */
 #define LIMIT_BOOST_ZONED_GC	25 /* percentage over total user space of boosted gc for zoned devices */
 #define DEF_MIGRATION_WINDOW_GRANULARITY_ZONED	3
+#define BOOST_GC_MULTIPLE	5
 
 #define DEF_GC_FAILED_PINNED_FILES	2048