Revert "f2fs: block cache/dio write during f2fs_enable_checkpoint()"

This reverts commit 196c81f.

Original patch may cause below deadlock, revert it.

write				remount
- write_begin
 - lock_page  --- lock A
 - prepare_write_begin
  - f2fs_map_lock
				- f2fs_enable_checkpoint
				 - down_write(cp_enable_rwsem)  --- lock B
				 - sync_inode_sb
				  - writepages
				   - lock_page			--- lock A
   - down_read(cp_enable_rwsem)  --- lock A

Cc: stable@kernel.org
Fixes: 196c81f ("f2fs: block cache/dio write during f2fs_enable_checkpoint()")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: chaseyu

fs/f2fs/data.c

@@ -1474,7 +1474,6 @@ static void f2fs_map_lock(struct f2fs_sb_info *sbi,
 				struct f2fs_lock_context *lc,
 				int flag)
 {
-	f2fs_down_read(&sbi->cp_enable_rwsem);
 	if (flag == F2FS_GET_BLOCK_PRE_AIO)
 		f2fs_down_read_trace(&sbi->node_change, lc);
 	else
@@ -1489,7 +1488,6 @@ static void f2fs_map_unlock(struct f2fs_sb_info *sbi,
 		f2fs_up_read_trace(&sbi->node_change, lc);
 	else
 		f2fs_unlock_op(sbi, lc);
-	f2fs_up_read(&sbi->cp_enable_rwsem);
 }
 
 int f2fs_get_block_locked(struct dnode_of_data *dn, pgoff_t index)

fs/f2fs/f2fs.h

@@ -311,7 +311,7 @@ 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		5	/* 5 secs */
+#define DEF_ENABLE_INTERVAL		16	/* 16 secs */
 #define DEF_DISABLE_QUICK_INTERVAL	1	/* 1 secs */
 #define DEF_UMOUNT_DISCARD_TIMEOUT	5	/* 5 secs */
 
@@ -1762,7 +1762,6 @@ struct f2fs_sb_info {
 	long interval_time[MAX_TIME];		/* to store thresholds */
 	struct ckpt_req_control cprc_info;	/* for checkpoint request control */
 	struct cp_stats cp_stats;		/* for time stat of checkpoint */
-	struct f2fs_rwsem cp_enable_rwsem;	/* block cache/dio write */
 
 	struct inode_management im[MAX_INO_ENTRY];	/* manage inode cache */
 

fs/f2fs/super.c

@@ -2687,12 +2687,11 @@ 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, lock, sync_inode, end;
+	long long start, writeback, end;
 	int ret;
 	struct f2fs_lock_context lc;
 
-	f2fs_info(sbi, "%s start, meta: %lld, node: %lld, data: %lld",
-					__func__,
+	f2fs_info(sbi, "f2fs_enable_checkpoint() starts, meta: %lld, node: %lld, data: %lld",
 					get_pages(sbi, F2FS_DIRTY_META),
 					get_pages(sbi, F2FS_DIRTY_NODES),
 					get_pages(sbi, F2FS_DIRTY_DATA));
@@ -2711,18 +2710,11 @@ static int f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
 	}
 	writeback = ktime_get();
 
-	f2fs_down_write(&sbi->cp_enable_rwsem);
-
-	lock = ktime_get();
-
-	if (get_pages(sbi, F2FS_DIRTY_DATA))
-		sync_inodes_sb(sbi->sb);
+	sync_inodes_sb(sbi->sb);
 
 	if (unlikely(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_warn(sbi, "checkpoint=enable has some unwritten data: %lld",
+					get_pages(sbi, F2FS_DIRTY_DATA));
 
 	f2fs_down_write_trace(&sbi->gc_lock, &lc);
 	f2fs_dirty_to_prefree(sbi);
@@ -2731,31 +2723,18 @@ static int f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
 	set_sbi_flag(sbi, SBI_IS_DIRTY);
 	f2fs_up_write_trace(&sbi->gc_lock, &lc);
 
-	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);
 
 	/* 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, "%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));
+	f2fs_info(sbi, "f2fs_enable_checkpoint() finishes, writeback:%llu, sync:%llu",
+					ktime_ms_delta(writeback, start),
+					ktime_ms_delta(end, writeback));
 	return ret;
 }
 
@@ -4952,7 +4931,6 @@ static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc)
 	init_f2fs_rwsem_trace(&sbi->node_change, sbi, LOCK_NAME_NODE_CHANGE);
 	spin_lock_init(&sbi->stat_lock);
 	init_f2fs_rwsem_trace(&sbi->cp_rwsem, sbi, LOCK_NAME_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);