BACKPORT: f2fs: block cache/dio write during f2fs_enable_checkpoint()

If there are too many background IOs during f2fs_enable_checkpoint(),
sync_inodes_sb() may be blocked for long time due to it will loop to
write dirty datas which are generated by in parallel write()
continuously.

Let's change as below to resolve this issue:
- hold cp_enable_rwsem write lock to block any cache/dio write
- decrease DEF_ENABLE_INTERVAL from 16 to 5

In addition, dump more logs during f2fs_enable_checkpoint().

Testcase:
1. fill data into filesystem until 90% usage.
2. mount -o remount,checkpoint=disable:10% /data
3. fio --rw=randwrite  --bs=4kb  --size=1GB  --numjobs=10  \
--iodepth=64  --ioengine=psync  --time_based  --runtime=600 \
--directory=/data/fio_dir/ &
4. mount -o remount,checkpoint=enable /data

Before:
F2FS-fs (dm-51): f2fs_enable_checkpoint() finishes, writeback:7232, sync:39793, cp:457

After:
F2FS-fs (dm-51): f2fs_enable_checkpoint end, writeback:5032, lock:0, sync_inode:5552, sync_fs:84

Bug: 432265814
Change-Id: Ie182108dcaa4903b603cb183f5c8c836f589b1ae
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
(cherry picked from commit 196c81fdd438f7ac429d5639090a9816abb9760a)
Signed-off-by: Chao Yu <chao@kernel.org>
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 915ae8f..66a4356 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1499,6 +1499,7 @@ static int __allocate_data_block(struct dnode_of_data *dn, int seg_type)
 
 static void f2fs_map_lock(struct f2fs_sb_info *sbi, int flag)
 {
+	f2fs_down_read(&sbi->cp_enable_rwsem);
 	if (flag == F2FS_GET_BLOCK_PRE_AIO)
 		f2fs_down_read(&sbi->node_change);
 	else
@@ -1511,6 +1512,7 @@ static void f2fs_map_unlock(struct f2fs_sb_info *sbi, int flag)
 		f2fs_up_read(&sbi->node_change);
 	else
 		f2fs_unlock_op(sbi);
+	f2fs_up_read(&sbi->cp_enable_rwsem);
 }
 
 int f2fs_get_block_locked(struct dnode_of_data *dn, pgoff_t index)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 45432e5..a2a1c02 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -244,7 +244,7 @@ enum {
 #define DEF_CP_INTERVAL			60	/* 60 secs */
 #define DEF_IDLE_INTERVAL		5	/* 5 secs */
 #define DEF_DISABLE_INTERVAL		5	/* 5 secs */
-#define DEF_ENABLE_INTERVAL		16	/* 16 secs */
+#define DEF_ENABLE_INTERVAL		5	/* 5 secs */
 #define DEF_DISABLE_QUICK_INTERVAL	1	/* 1 secs */
 #define DEF_UMOUNT_DISCARD_TIMEOUT	5	/* 5 secs */
 
@@ -1578,6 +1578,7 @@ struct f2fs_sb_info {
 	unsigned long last_time[MAX_TIME];	/* to store time in jiffies */
 	long interval_time[MAX_TIME];		/* to store thresholds */
 	struct ckpt_req_control cprc_info;	/* for checkpoint request control */
+	struct f2fs_rwsem cp_enable_rwsem;	/* block cache/dio write */
 
 	struct inode_management im[MAX_INO_ENTRY];	/* manage inode cache */
 
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 0a43496..bd8e740 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2298,10 +2298,11 @@ static int f2fs_disable_checkpoint(struct f2fs_sb_info *sbi)
 static int f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
 {
 	unsigned int nr_pages = get_pages(sbi, F2FS_DIRTY_DATA) / 16;
-	long long start, writeback, end;
+	long long start, writeback, lock, sync_inode, end;
 	int ret;
 
-	f2fs_info(sbi, "f2fs_enable_checkpoint() starts, meta: %lld, node: %lld, data: %lld",
+	f2fs_info(sbi, "%s start, meta: %lld, node: %lld, data: %lld",
+					__func__,
 					get_pages(sbi, F2FS_DIRTY_META),
 					get_pages(sbi, F2FS_DIRTY_NODES),
 					get_pages(sbi, F2FS_DIRTY_DATA));
@@ -2320,11 +2321,18 @@ static int f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
 	}
 	writeback = ktime_get();
 
-	sync_inodes_sb(sbi->sb);
+	f2fs_down_write(&sbi->cp_enable_rwsem);
+
+	lock = ktime_get();
+
+	if (get_pages(sbi, F2FS_DIRTY_DATA))
+		sync_inodes_sb(sbi->sb);
 
 	if (unlikely(get_pages(sbi, F2FS_DIRTY_DATA)))
-		f2fs_warn(sbi, "checkpoint=enable has some unwritten data: %lld",
-					get_pages(sbi, F2FS_DIRTY_DATA));
+		f2fs_warn(sbi, "%s: has some unwritten data: %lld",
+			__func__, get_pages(sbi, F2FS_DIRTY_DATA));
+
+	sync_inode = ktime_get();
 
 	f2fs_down_write(&sbi->gc_lock);
 	f2fs_dirty_to_prefree(sbi);
@@ -2333,6 +2341,13 @@ static int f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
 	set_sbi_flag(sbi, SBI_IS_DIRTY);
 	f2fs_up_write(&sbi->gc_lock);
 
+	f2fs_info(sbi, "%s sync_fs, meta: %lld, imeta: %lld, node: %lld, dents: %lld, qdata: %lld",
+					__func__,
+					get_pages(sbi, F2FS_DIRTY_META),
+					get_pages(sbi, F2FS_DIRTY_IMETA),
+					get_pages(sbi, F2FS_DIRTY_NODES),
+					get_pages(sbi, F2FS_DIRTY_DENTS),
+					get_pages(sbi, F2FS_DIRTY_QDATA));
 	ret = f2fs_sync_fs(sbi->sb, 1);
 	if (ret)
 		f2fs_err(sbi, "%s sync_fs failed, ret: %d", __func__, ret);
@@ -2340,11 +2355,17 @@ static int f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
 	/* Let's ensure there's no pending checkpoint anymore */
 	f2fs_flush_ckpt_thread(sbi);
 
+	f2fs_up_write(&sbi->cp_enable_rwsem);
+
 	end = ktime_get();
 
-	f2fs_info(sbi, "f2fs_enable_checkpoint() finishes, writeback:%llu, sync:%llu",
-					ktime_ms_delta(writeback, start),
-					ktime_ms_delta(end, writeback));
+	f2fs_info(sbi, "%s end, writeback:%llu, "
+				"lock:%llu, sync_inode:%llu, sync_fs:%llu",
+				__func__,
+				ktime_ms_delta(writeback, start),
+				ktime_ms_delta(lock, writeback),
+				ktime_ms_delta(sync_inode, lock),
+				ktime_ms_delta(end, sync_inode));
 	return ret;
 }
 
@@ -4346,6 +4367,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 	init_f2fs_rwsem(&sbi->node_change);
 	spin_lock_init(&sbi->stat_lock);
 	init_f2fs_rwsem(&sbi->cp_rwsem);
+	init_f2fs_rwsem(&sbi->cp_enable_rwsem);
 	init_f2fs_rwsem(&sbi->quota_sem);
 	init_waitqueue_head(&sbi->cp_wait);
 	spin_lock_init(&sbi->error_lock);