f2fs: enable atgc dynamically if conditions are met

Now atgc can only be enabled when umounted->mounted device
even related conditions have reached. If the device has not
be umounted->mounted for a long time, atgc can not work.

So enable atgc dynamically when atgc_age_threshold is less than
elapsed_time and ATGC mount option is on.
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/checkpoint.c

@@ -1718,6 +1718,7 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 	}
 
 	f2fs_restore_inmem_curseg(sbi);
+	f2fs_reinit_atgc_curseg(sbi);
 	stat_inc_cp_count(sbi);
 stop:
 	unblock_operations(sbi);

fs/f2fs/f2fs.h

@@ -3693,6 +3693,7 @@ void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi);
 int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra);
 bool f2fs_segment_has_free_slot(struct f2fs_sb_info *sbi, int segno);
 int f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi);
+int f2fs_reinit_atgc_curseg(struct f2fs_sb_info *sbi);
 void f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi);
 void f2fs_restore_inmem_curseg(struct f2fs_sb_info *sbi);
 int f2fs_allocate_segment_for_resize(struct f2fs_sb_info *sbi, int type,

fs/f2fs/segment.c

@@ -2931,12 +2931,12 @@ static int get_atssr_segment(struct f2fs_sb_info *sbi, int type,
 	return ret;
 }
 
-static int __f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi)
+static int __f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi, bool force)
 {
 	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_ALL_DATA_ATGC);
 	int ret = 0;
 
-	if (!sbi->am.atgc_enabled)
+	if (!sbi->am.atgc_enabled && !force)
 		return 0;
 
 	f2fs_down_read(&SM_I(sbi)->curseg_lock);
@@ -2953,9 +2953,30 @@ static int __f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi)
 	f2fs_up_read(&SM_I(sbi)->curseg_lock);
 	return ret;
 }
+
 int f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi)
 {
-	return __f2fs_init_atgc_curseg(sbi);
+	return __f2fs_init_atgc_curseg(sbi, false);
+}
+
+int f2fs_reinit_atgc_curseg(struct f2fs_sb_info *sbi)
+{
+	int ret;
+
+	if (!test_opt(sbi, ATGC))
+		return 0;
+	if (sbi->am.atgc_enabled)
+		return 0;
+	if (le64_to_cpu(F2FS_CKPT(sbi)->elapsed_time) <
+			sbi->am.age_threshold)
+		return 0;
+
+	ret = __f2fs_init_atgc_curseg(sbi, true);
+	if (!ret) {
+		sbi->am.atgc_enabled = true;
+		f2fs_info(sbi, "reenabled age threshold GC");
+	}
+	return ret;
 }
 
 static void __f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi, int type)