fs/direct-io: Reduce the size of struct dio

Reduce the size of struct dio by combining the 'op' and 'op_flags' into
the new 'opf' member. Use the new blk_opf_t type to improve static type
checking. This patch does not change any functionality.
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20220714180729.1065367-49-bvanassche@acm.orgSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/direct-io.c

@@ -117,8 +117,7 @@ struct dio_submit {
 /* dio_state communicated between submission path and end_io */
 struct dio {
 	int flags;			/* doesn't change */
-	int op;
-	int op_flags;
+	blk_opf_t opf;			/* request operation type and flags */
 	struct gendisk *bio_disk;
 	struct inode *inode;
 	loff_t i_size;			/* i_size when submitted */
@@ -167,12 +166,13 @@ static inline unsigned dio_pages_present(struct dio_submit *sdio)
  */
 static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)
 {
+	const enum req_op dio_op = dio->opf & REQ_OP_MASK;
 	ssize_t ret;
 
 	ret = iov_iter_get_pages(sdio->iter, dio->pages, LONG_MAX, DIO_PAGES,
 				&sdio->from);
 
-	if (ret < 0 && sdio->blocks_available && (dio->op == REQ_OP_WRITE)) {
+	if (ret < 0 && sdio->blocks_available && dio_op == REQ_OP_WRITE) {
 		struct page *page = ZERO_PAGE(0);
 		/*
 		 * A memory fault, but the filesystem has some outstanding
@@ -234,6 +234,7 @@ static inline struct page *dio_get_page(struct dio *dio,
  */
 static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags)
 {
+	const enum req_op dio_op = dio->opf & REQ_OP_MASK;
 	loff_t offset = dio->iocb->ki_pos;
 	ssize_t transferred = 0;
 	int err;
@@ -251,7 +252,7 @@ static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags)
 		transferred = dio->result;
 
 		/* Check for short read case */
-		if ((dio->op == REQ_OP_READ) &&
+		if (dio_op == REQ_OP_READ &&
 		    ((offset + transferred) > dio->i_size))
 			transferred = dio->i_size - offset;
 		/* ignore EFAULT if some IO has been done */
@@ -286,7 +287,7 @@ static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags)
 	 * zeros from unwritten extents.
 	 */
 	if (flags & DIO_COMPLETE_INVALIDATE &&
-	    ret > 0 && dio->op == REQ_OP_WRITE &&
+	    ret > 0 && dio_op == REQ_OP_WRITE &&
 	    dio->inode->i_mapping->nrpages) {
 		err = invalidate_inode_pages2_range(dio->inode->i_mapping,
 					offset >> PAGE_SHIFT,
@@ -305,7 +306,7 @@ static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags)
 		 */
 		dio->iocb->ki_pos += transferred;
 
-		if (ret > 0 && dio->op == REQ_OP_WRITE)
+		if (ret > 0 && dio_op == REQ_OP_WRITE)
 			ret = generic_write_sync(dio->iocb, ret);
 		dio->iocb->ki_complete(dio->iocb, ret);
 	}
@@ -329,6 +330,7 @@ static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio);
 static void dio_bio_end_aio(struct bio *bio)
 {
 	struct dio *dio = bio->bi_private;
+	const enum req_op dio_op = dio->opf & REQ_OP_MASK;
 	unsigned long remaining;
 	unsigned long flags;
 	bool defer_completion = false;
@@ -353,7 +355,7 @@ static void dio_bio_end_aio(struct bio *bio)
 		 */
 		if (dio->result)
 			defer_completion = dio->defer_completion ||
-					   (dio->op == REQ_OP_WRITE &&
+					   (dio_op == REQ_OP_WRITE &&
 					    dio->inode->i_mapping->nrpages);
 		if (defer_completion) {
 			INIT_WORK(&dio->complete_work, dio_aio_complete_work);
@@ -396,7 +398,7 @@ dio_bio_alloc(struct dio *dio, struct dio_submit *sdio,
 	 * bio_alloc() is guaranteed to return a bio when allowed to sleep and
 	 * we request a valid number of vectors.
 	 */
-	bio = bio_alloc(bdev, nr_vecs, dio->op | dio->op_flags, GFP_KERNEL);
+	bio = bio_alloc(bdev, nr_vecs, dio->opf, GFP_KERNEL);
 	bio->bi_iter.bi_sector = first_sector;
 	if (dio->is_async)
 		bio->bi_end_io = dio_bio_end_aio;
@@ -415,6 +417,7 @@ dio_bio_alloc(struct dio *dio, struct dio_submit *sdio,
  */
 static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)
 {
+	const enum req_op dio_op = dio->opf & REQ_OP_MASK;
 	struct bio *bio = sdio->bio;
 	unsigned long flags;
 
@@ -426,7 +429,7 @@ static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)
 	dio->refcount++;
 	spin_unlock_irqrestore(&dio->bio_lock, flags);
 
-	if (dio->is_async && dio->op == REQ_OP_READ && dio->should_dirty)
+	if (dio->is_async && dio_op == REQ_OP_READ && dio->should_dirty)
 		bio_set_pages_dirty(bio);
 
 	dio->bio_disk = bio->bi_bdev->bd_disk;
@@ -492,7 +495,8 @@ static struct bio *dio_await_one(struct dio *dio)
 static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio)
 {
 	blk_status_t err = bio->bi_status;
-	bool should_dirty = dio->op == REQ_OP_READ && dio->should_dirty;
+	const enum req_op dio_op = dio->opf & REQ_OP_MASK;
+	bool should_dirty = dio_op == REQ_OP_READ && dio->should_dirty;
 
 	if (err) {
 		if (err == BLK_STS_AGAIN && (bio->bi_opf & REQ_NOWAIT))
@@ -619,6 +623,7 @@ static int dio_set_defer_completion(struct dio *dio)
 static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
 			   struct buffer_head *map_bh)
 {
+	const enum req_op dio_op = dio->opf & REQ_OP_MASK;
 	int ret;
 	sector_t fs_startblk;	/* Into file, in filesystem-sized blocks */
 	sector_t fs_endblk;	/* Into file, in filesystem-sized blocks */
@@ -653,7 +658,7 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
 		 * which may decide to handle it or also return an unmapped
 		 * buffer head.
 		 */
-		create = dio->op == REQ_OP_WRITE;
+		create = dio_op == REQ_OP_WRITE;
 		if (dio->flags & DIO_SKIP_HOLES) {
 			i_size = i_size_read(dio->inode);
 			if (i_size && fs_startblk <= (i_size - 1) >> i_blkbits)
@@ -801,10 +806,11 @@ submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page,
 		    unsigned offset, unsigned len, sector_t blocknr,
 		    struct buffer_head *map_bh)
 {
+	const enum req_op dio_op = dio->opf & REQ_OP_MASK;
 	int ret = 0;
 	int boundary = sdio->boundary;	/* dio_send_cur_page may clear it */
 
-	if (dio->op == REQ_OP_WRITE) {
+	if (dio_op == REQ_OP_WRITE) {
 		/*
 		 * Read accounting is performed in submit_bio()
 		 */
@@ -917,6 +923,7 @@ static inline void dio_zero_block(struct dio *dio, struct dio_submit *sdio,
 static int do_direct_IO(struct dio *dio, struct dio_submit *sdio,
 			struct buffer_head *map_bh)
 {
+	const enum req_op dio_op = dio->opf & REQ_OP_MASK;
 	const unsigned blkbits = sdio->blkbits;
 	const unsigned i_blkbits = blkbits + sdio->blkfactor;
 	int ret = 0;
@@ -992,7 +999,7 @@ static int do_direct_IO(struct dio *dio, struct dio_submit *sdio,
 				loff_t i_size_aligned;
 
 				/* AKPM: eargh, -ENOTBLK is a hack */
-				if (dio->op == REQ_OP_WRITE) {
+				if (dio_op == REQ_OP_WRITE) {
 					put_page(page);
 					return -ENOTBLK;
 				}
@@ -1196,12 +1203,11 @@ ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
 
 	dio->inode = inode;
 	if (iov_iter_rw(iter) == WRITE) {
-		dio->op = REQ_OP_WRITE;
-		dio->op_flags = REQ_SYNC | REQ_IDLE;
+		dio->opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
 		if (iocb->ki_flags & IOCB_NOWAIT)
-			dio->op_flags |= REQ_NOWAIT;
+			dio->opf |= REQ_NOWAIT;
 	} else {
-		dio->op = REQ_OP_READ;
+		dio->opf = REQ_OP_READ;
 	}
 
 	/*