f2fs: use bio count instead of F2FS_WRITEBACK page count

This can reduce page counting overhead.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/checkpoint.c

@@ -914,7 +914,7 @@ static void wait_on_all_pages_writeback(struct f2fs_sb_info *sbi)
 	for (;;) {
 		prepare_to_wait(&sbi->cp_wait, &wait, TASK_UNINTERRUPTIBLE);
 
-		if (!get_pages(sbi, F2FS_WRITEBACK))
+		if (!atomic_read(&sbi->nr_wb_bios))
 			break;
 
 		io_schedule_timeout(5*HZ);

fs/f2fs/data.c

@@ -71,10 +71,9 @@ static void f2fs_write_end_io(struct bio *bio)
 			f2fs_stop_checkpoint(sbi);
 		}
 		end_page_writeback(page);
-		dec_page_count(sbi, F2FS_WRITEBACK);
 	}
-
-	if (!get_pages(sbi, F2FS_WRITEBACK) && wq_has_sleeper(&sbi->cp_wait))
+	if (atomic_dec_and_test(&sbi->nr_wb_bios) &&
+				wq_has_sleeper(&sbi->cp_wait))
 		wake_up(&sbi->cp_wait);
 
 	bio_put(bio);
@@ -98,6 +97,14 @@ static struct bio *__bio_alloc(struct f2fs_sb_info *sbi, block_t blk_addr,
 	return bio;
 }
 
+static inline void __submit_bio(struct f2fs_sb_info *sbi, int rw,
+						struct bio *bio)
+{
+	if (!is_read_io(rw))
+		atomic_inc(&sbi->nr_wb_bios);
+	submit_bio(rw, bio);
+}
+
 static void __submit_merged_bio(struct f2fs_bio_info *io)
 {
 	struct f2fs_io_info *fio = &io->fio;
@@ -110,7 +117,7 @@ static void __submit_merged_bio(struct f2fs_bio_info *io)
 	else
 		trace_f2fs_submit_write_bio(io->sbi->sb, fio, io->bio);
 
-	submit_bio(fio->rw, io->bio);
+	__submit_bio(io->sbi, fio->rw, io->bio);
 	io->bio = NULL;
 }
 
@@ -228,7 +235,7 @@ int f2fs_submit_page_bio(struct f2fs_io_info *fio)
 		return -EFAULT;
 	}
 
-	submit_bio(fio->rw, bio);
+	__submit_bio(fio->sbi, fio->rw, bio);
 	return 0;
 }
 
@@ -248,9 +255,6 @@ void f2fs_submit_page_mbio(struct f2fs_io_info *fio)
 
 	down_write(&io->io_rwsem);
 
-	if (!is_read)
-		inc_page_count(sbi, F2FS_WRITEBACK);
-
 	if (io->bio && (io->last_block_in_bio != fio->new_blkaddr - 1 ||
 						io->fio.rw != fio->rw))
 		__submit_merged_bio(io);
@@ -1047,7 +1051,7 @@ static int f2fs_mpage_readpages(struct address_space *mapping,
 		 */
 		if (bio && (last_block_in_bio != block_nr - 1)) {
 submit_and_realloc:
-			submit_bio(READ, bio);
+			__submit_bio(F2FS_I_SB(inode), READ, bio);
 			bio = NULL;
 		}
 		if (bio == NULL) {
@@ -1090,7 +1094,7 @@ static int f2fs_mpage_readpages(struct address_space *mapping,
 		goto next_page;
 confused:
 		if (bio) {
-			submit_bio(READ, bio);
+			__submit_bio(F2FS_I_SB(inode), READ, bio);
 			bio = NULL;
 		}
 		unlock_page(page);
@@ -1100,7 +1104,7 @@ static int f2fs_mpage_readpages(struct address_space *mapping,
 	}
 	BUG_ON(pages && !list_empty(pages));
 	if (bio)
-		submit_bio(READ, bio);
+		__submit_bio(F2FS_I_SB(inode), READ, bio);
 	return 0;
 }
 

fs/f2fs/debug.c

@@ -48,7 +48,7 @@ static void update_general_status(struct f2fs_sb_info *sbi)
 	si->ndirty_dirs = sbi->ndirty_inode[DIR_INODE];
 	si->ndirty_files = sbi->ndirty_inode[FILE_INODE];
 	si->inmem_pages = get_pages(sbi, F2FS_INMEM_PAGES);
-	si->wb_pages = get_pages(sbi, F2FS_WRITEBACK);
+	si->wb_bios = atomic_read(&sbi->nr_wb_bios);
 	si->total_count = (int)sbi->user_block_count / sbi->blocks_per_seg;
 	si->rsvd_segs = reserved_segments(sbi);
 	si->overp_segs = overprovision_segments(sbi);
@@ -299,8 +299,8 @@ 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, "  - inmem: %4d, wb: %4d\n",
-			   si->inmem_pages, si->wb_pages);
+		seq_printf(s, "  - inmem: %4d, wb_bios: %4d\n",
+			   si->inmem_pages, si->wb_bios);
 		seq_printf(s, "  - nodes: %4d in %4d\n",
 			   si->ndirty_node, si->node_pages);
 		seq_printf(s, "  - dents: %4d in dirs:%4d\n",

fs/f2fs/f2fs.h

@@ -650,7 +650,6 @@ struct f2fs_sm_info {
  * dirty dentry blocks, dirty node blocks, and dirty meta blocks.
  */
 enum count_type {
-	F2FS_WRITEBACK,
 	F2FS_DIRTY_DENTS,
 	F2FS_DIRTY_DATA,
 	F2FS_DIRTY_NODES,
@@ -813,6 +812,7 @@ struct f2fs_sb_info {
 	block_t discard_blks;			/* discard command candidats */
 	block_t last_valid_block_count;		/* for recovery */
 	u32 s_next_generation;			/* for NFS support */
+	atomic_t nr_wb_bios;			/* # of writeback bios */
 	atomic_t nr_pages[NR_COUNT_TYPE];	/* # of pages, see count_type */
 
 	struct f2fs_mount_info mount_opt;	/* mount options */
@@ -2017,7 +2017,7 @@ struct f2fs_stat_info {
 	int ndirty_dent, ndirty_dirs, ndirty_data, ndirty_files;
 	int nats, dirty_nats, sits, dirty_sits, fnids;
 	int total_count, utilization;
-	int bg_gc, inmem_pages, wb_pages;
+	int bg_gc, inmem_pages, wb_bios;
 	int inline_xattr, inline_inode, inline_dir, orphans;
 	unsigned int valid_count, valid_node_count, valid_inode_count;
 	unsigned int bimodal, avg_vblocks;

fs/f2fs/super.c

@@ -649,8 +649,7 @@ static void f2fs_put_super(struct super_block *sb)
 	mutex_unlock(&sbi->umount_mutex);
 
 	/* our cp_error case, we can wait for any writeback page */
-	if (get_pages(sbi, F2FS_WRITEBACK))
-		f2fs_flush_merged_bios(sbi);
+	f2fs_flush_merged_bios(sbi);
 
 	iput(sbi->node_inode);
 	iput(sbi->meta_inode);