f2fs: fix wrong inflight page stats for directIO

Previously, we use sbi->nr_pages[] to account direct IO, the count should
be based on page granularity rather than bio granularity, fix it.

Fixes: 02b16d0 ("f2fs: add to account direct IO")
Signed-off-by: Chao Yu <chao@kernel.org>

fs/f2fs/data.c

@@ -3494,8 +3494,9 @@ 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);
+	dec_page_counts(F2FS_I_SB(dio->inode),
+			dio->write ? F2FS_DIO_WRITE : F2FS_DIO_READ,
+			dio->blkcnt);
 
 	bio->bi_private = dio->orig_private;
 	bio->bi_end_io = dio->orig_end_io;
@@ -3519,13 +3520,14 @@ static void f2fs_dio_submit_bio(struct bio *bio, struct inode *inode,
 	dio->inode = inode;
 	dio->orig_end_io = bio->bi_end_io;
 	dio->orig_private = bio->bi_private;
+	dio->blkcnt = blkcnt;
 	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);
+	inc_page_counts(F2FS_I_SB(inode),
+			write ? F2FS_DIO_WRITE : F2FS_DIO_READ, dio->blkcnt);
 
 	submit_bio(bio);
 	return;

fs/f2fs/f2fs.h

@@ -1759,6 +1759,7 @@ struct f2fs_private_dio {
 	struct inode *inode;
 	void *orig_private;
 	bio_end_io_t *orig_end_io;
+	unsigned int blkcnt;
 	bool write;
 };
 
@@ -2267,6 +2268,12 @@ static inline void inc_page_count(struct f2fs_sb_info *sbi, int count_type)
 		set_sbi_flag(sbi, SBI_IS_DIRTY);
 }
 
+static inline void inc_page_counts(struct f2fs_sb_info *sbi, int count_type,
+							unsigned int count)
+{
+	atomic_add(count, &sbi->nr_pages[count_type]);
+}
+
 static inline void inode_inc_dirty_pages(struct inode *inode)
 {
 	atomic_inc(&F2FS_I(inode)->dirty_pages);
@@ -2281,6 +2288,12 @@ static inline void dec_page_count(struct f2fs_sb_info *sbi, int count_type)
 	atomic_dec(&sbi->nr_pages[count_type]);
 }
 
+static inline void dec_page_counts(struct f2fs_sb_info *sbi, int count_type,
+							unsigned int count)
+{
+	atomic_sub(count, &sbi->nr_pages[count_type]);
+}
+
 static inline void inode_dec_dirty_pages(struct inode *inode)
 {
 	if (!S_ISDIR(inode->i_mode) && !S_ISREG(inode->i_mode) &&