f2fs: account read IOs and use IO counts for is_idle

This patch adds issued read IO counts which is under block layer.

Chao modified a bit, since:

Below race can cause reversed reference on F2FS_RD_DATA, there is
the same issue in f2fs_submit_page_bio(), fix them by relocate
__submit_bio() and inc_page_count.

Thread A			Thread B
- f2fs_write_begin
 - f2fs_submit_page_read
 - __submit_bio
				- f2fs_read_end_io
				 - __read_end_io
				 - dec_page_count(, F2FS_RD_DATA)
 - inc_page_count(, F2FS_RD_DATA)

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -950,6 +950,9 @@ enum count_type {
 	F2FS_DIRTY_IMETA,
 	F2FS_WB_CP_DATA,
 	F2FS_WB_DATA,
+	F2FS_RD_DATA,
+	F2FS_RD_NODE,
+	F2FS_RD_META,
 	NR_COUNT_TYPE,
 };
 
@@ -1392,11 +1395,6 @@ static inline unsigned int f2fs_time_to_wait(struct f2fs_sb_info *sbi,
 	return wait_ms;
 }
 
-static inline bool is_idle(struct f2fs_sb_info *sbi, int type)
-{
-	return f2fs_time_over(sbi, type);
-}
-
 /*
  * Inline functions
  */
@@ -1787,7 +1785,9 @@ static inline void inc_page_count(struct f2fs_sb_info *sbi, int count_type)
 	atomic_inc(&sbi->nr_pages[count_type]);
 
 	if (count_type == F2FS_DIRTY_DATA || count_type == F2FS_INMEM_PAGES ||
-		count_type == F2FS_WB_CP_DATA || count_type == F2FS_WB_DATA)
+		count_type == F2FS_WB_CP_DATA || count_type == F2FS_WB_DATA ||
+		count_type == F2FS_RD_DATA || count_type == F2FS_RD_NODE ||
+		count_type == F2FS_RD_META)
 		return;
 
 	set_sbi_flag(sbi, SBI_IS_DIRTY);
@@ -2124,6 +2124,15 @@ static inline struct bio *f2fs_bio_alloc(struct f2fs_sb_info *sbi,
 	return bio_alloc(GFP_KERNEL, npages);
 }
 
+static inline bool is_idle(struct f2fs_sb_info *sbi, int type)
+{
+	if (get_pages(sbi, F2FS_RD_DATA) || get_pages(sbi, F2FS_RD_NODE) ||
+		get_pages(sbi, F2FS_RD_META) || get_pages(sbi, F2FS_WB_DATA) ||
+		get_pages(sbi, F2FS_WB_CP_DATA))
+		return false;
+	return f2fs_time_over(sbi, type);
+}
+
 static inline void f2fs_radix_tree_insert(struct radix_tree_root *root,
 				unsigned long index, void *item)
 {
@@ -3114,6 +3123,7 @@ struct f2fs_stat_info {
 	int free_nids, avail_nids, alloc_nids;
 	int total_count, utilization;
 	int bg_gc, nr_wb_cp_data, nr_wb_data;
+	int nr_rd_data, nr_rd_node, nr_rd_meta;
 	unsigned int io_skip_bggc, other_skip_bggc;
 	int nr_flushing, nr_flushed, flush_list_empty;
 	int nr_discarding, nr_discarded;