[PATCH v2] f2fs: add to account direct IO

[Chao Yu]

From: Chao Yu <yuchao0@xxxxxxxxxx>

This patch adds f2fs_dio_submit_bio() to hook submit_io/end_io functions
in direct IO path, in order to account DIO.

Later, we will add this count into is_idle() to let background GC/Discard
thread be aware of DIO.

Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
---
v2:
- access bio->bi_status instead of dead bio->bi_error.
 fs/f2fs/data.c  | 51 ++++++++++++++++++++++++++++++++++++++++++++++++-
 fs/f2fs/debug.c |  4 ++++
 fs/f2fs/f2fs.h  | 10 ++++++++++
 3 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 5245499203bf..6b30142c3321 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2604,6 +2604,53 @@ static int check_direct_IO(struct inode *inode, struct iov_iter *iter,
 	return 0;
 }
 
+static void f2fs_dio_end_io(struct bio *bio)
+{
+	struct f2fs_private_dio *dio = bio->bi_private;
+
+	dec_page_count(F2FS_I_SB(dio->inode),
+			dio->write ? F2FS_DIO_WRITE : F2FS_DIO_READ);
+
+	bio->bi_private = dio->orig_private;
+	bio->bi_end_io = dio->orig_end_io;
+
+	kfree(dio);
+
+	bio_endio(bio);
+}
+
+static void f2fs_dio_submit_bio(struct bio *bio, struct inode *inode,
+							loff_t file_offset)
+{
+	struct f2fs_private_dio *dio;
+	bool write = (bio_op(bio) == REQ_OP_WRITE);
+	int err;
+
+	dio = f2fs_kzalloc(F2FS_I_SB(inode),
+			sizeof(struct f2fs_private_dio), GFP_NOFS);
+	if (!dio) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	dio->inode = inode;
+	dio->orig_end_io = bio->bi_end_io;
+	dio->orig_private = bio->bi_private;
+	dio->write = write;
+
+	bio->bi_end_io = f2fs_dio_end_io;
+	bio->bi_private = dio;
+
+	inc_page_count(F2FS_I_SB(inode),
+			write ? F2FS_DIO_WRITE : F2FS_DIO_READ);
+
+	submit_bio(bio);
+	return;
+out:
+	bio->bi_status = BLK_STS_IOERR;
+	bio_endio(bio);
+}
+
 static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 {
 	struct address_space *mapping = iocb->ki_filp->f_mapping;
@@ -2650,7 +2697,9 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 			down_read(&fi->i_gc_rwsem[READ]);
 	}
 
-	err = blockdev_direct_IO(iocb, inode, iter, get_data_block_dio);
+	err = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
+			iter, get_data_block_dio, NULL, f2fs_dio_submit_bio,
+			DIO_LOCKING | DIO_SKIP_HOLES);
 
 	if (do_opu)
 		up_read(&fi->i_gc_rwsem[READ]);
diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index e327eefdbc02..06e72f9c8654 100644
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -53,6 +53,8 @@ static void update_general_status(struct f2fs_sb_info *sbi)
 	si->vw_cnt = atomic_read(&sbi->vw_cnt);
 	si->max_aw_cnt = atomic_read(&sbi->max_aw_cnt);
 	si->max_vw_cnt = atomic_read(&sbi->max_vw_cnt);
+	si->nr_dio_read = get_pages(sbi, F2FS_DIO_READ);
+	si->nr_dio_write = get_pages(sbi, F2FS_DIO_WRITE);
 	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);
@@ -374,6 +376,8 @@ 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, "  - DIO (R: %4d, W: %4d)\n",
+			   si->nr_dio_read, si->nr_dio_write);
 		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), "
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 70009709d50c..3a0fc17f1e7a 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -951,6 +951,8 @@ enum count_type {
 	F2FS_RD_DATA,
 	F2FS_RD_NODE,
 	F2FS_RD_META,
+	F2FS_DIO_WRITE,
+	F2FS_DIO_READ,
 	NR_COUNT_TYPE,
 };
 
@@ -1340,6 +1342,13 @@ struct f2fs_sb_info {
 	__u32 s_chksum_seed;
 };
 
+struct f2fs_private_dio {
+	struct inode *inode;
+	void *orig_private;
+	bio_end_io_t *orig_end_io;
+	bool write;
+};
+
 #ifdef CONFIG_F2FS_FAULT_INJECTION
 #define f2fs_show_injection_info(type)					\
 	printk_ratelimited("%sF2FS-fs : inject %s in %s of %pF\n",	\
@@ -3163,6 +3172,7 @@ struct f2fs_stat_info {
 	int total_count, utilization;
 	int bg_gc, nr_wb_cp_data, nr_wb_data;
 	int nr_rd_data, nr_rd_node, nr_rd_meta;
+	int nr_dio_read, nr_dio_write;
 	unsigned int io_skip_bggc, other_skip_bggc;
 	int nr_flushing, nr_flushed, flush_list_empty;
 	int nr_discarding, nr_discarded;
-- 
2.18.0