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/data.c

@@ -52,6 +52,23 @@ static bool __is_cp_guaranteed(struct page *page)
 	return false;
 }
 
+static enum count_type __read_io_type(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+
+	if (mapping) {
+		struct inode *inode = mapping->host;
+		struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+
+		if (inode->i_ino == F2FS_META_INO(sbi))
+			return F2FS_RD_META;
+
+		if (inode->i_ino == F2FS_NODE_INO(sbi))
+			return F2FS_RD_NODE;
+	}
+	return F2FS_RD_DATA;
+}
+
 /* postprocessing steps for read bios */
 enum bio_post_read_step {
 	STEP_INITIAL = 0,
@@ -82,6 +99,7 @@ static void __read_end_io(struct bio *bio)
 		} else {
 			SetPageUptodate(page);
 		}
+		dec_page_count(F2FS_P_SB(page), __read_io_type(page));
 		unlock_page(page);
 	}
 	if (bio->bi_private)
@@ -466,8 +484,8 @@ int f2fs_submit_page_bio(struct f2fs_io_info *fio)
 
 	bio_set_op_attrs(bio, fio->op, fio->op_flags);
 
-	if (!is_read_io(fio->op))
-		inc_page_count(fio->sbi, WB_DATA_TYPE(fio->page));
+	inc_page_count(fio->sbi, is_read_io(fio->op) ?
+			__read_io_type(page): WB_DATA_TYPE(fio->page));
 
 	__submit_bio(fio->sbi, bio, fio->type);
 	return 0;
@@ -598,6 +616,7 @@ static int f2fs_submit_page_read(struct inode *inode, struct page *page,
 		return -EFAULT;
 	}
 	ClearPageError(page);
+	inc_page_count(F2FS_I_SB(inode), F2FS_RD_DATA);
 	__submit_bio(F2FS_I_SB(inode), bio, DATA);
 	return 0;
 }
@@ -1586,6 +1605,7 @@ submit_and_realloc:
 		if (bio_add_page(bio, page, blocksize, 0) < blocksize)
 			goto submit_and_realloc;
 
+		inc_page_count(F2FS_I_SB(inode), F2FS_RD_DATA);
 		ClearPageError(page);
 		last_block_in_bio = block_nr;
 		goto next_page;

fs/f2fs/debug.c

@@ -55,6 +55,9 @@ static void update_general_status(struct f2fs_sb_info *sbi)
 	si->max_vw_cnt = atomic_read(&sbi->max_vw_cnt);
 	si->nr_wb_cp_data = get_pages(sbi, F2FS_WB_CP_DATA);
 	si->nr_wb_data = get_pages(sbi, F2FS_WB_DATA);
+	si->nr_rd_data = get_pages(sbi, F2FS_RD_DATA);
+	si->nr_rd_node = get_pages(sbi, F2FS_RD_NODE);
+	si->nr_rd_meta = get_pages(sbi, F2FS_RD_META);
 	if (SM_I(sbi) && SM_I(sbi)->fcc_info) {
 		si->nr_flushed =
 			atomic_read(&SM_I(sbi)->fcc_info->issued_flush);
@@ -371,7 +374,9 @@ static int stat_show(struct seq_file *s, void *v)
 		seq_printf(s, "  - Inner Struct Count: tree: %d(%d), node: %d\n",
 				si->ext_tree, si->zombie_tree, si->ext_node);
 		seq_puts(s, "\nBalancing F2FS Async:\n");
-		seq_printf(s, "  - IO (CP: %4d, Data: %4d, Flush: (%4d %4d %4d), "
+		seq_printf(s, "  - IO_R (Data: %4d, Node: %4d, Meta: %4d\n",
+			   si->nr_rd_data, si->nr_rd_node, si->nr_rd_meta);
+		seq_printf(s, "  - IO_W (CP: %4d, Data: %4d, Flush: (%4d %4d %4d), "
 			"Discard: (%4d %4d)) cmd: %4d undiscard:%4u\n",
 			   si->nr_wb_cp_data, si->nr_wb_data,
 			   si->nr_flushing, si->nr_flushed,

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;