[PATCH v2 48/63] fs/direct-io: Reduce the size of struct dio

[Bart Van Assche <bvanassche@acm.org>]

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.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 fs/direct-io.c | 37 ++++++++++++++++++++-----------------
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 840752006f60..b72706d163f5 100644
--- a/fs/direct-io.c
+++ b/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 */
@@ -154,6 +153,11 @@ struct dio {
 
 static struct kmem_cache *dio_cache __read_mostly;
 
+static inline bool op_is_read(blk_opf_t opf)
+{
+	return !op_is_write(opf);
+}
+
 /*
  * How many pages are in the queue?
  */
@@ -172,7 +176,7 @@ static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)
 	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 && op_is_write(dio->opf)) {
 		struct page *page = ZERO_PAGE(0);
 		/*
 		 * A memory fault, but the filesystem has some outstanding
@@ -251,7 +255,7 @@ 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 (op_is_read(dio->opf) &&
 		    ((offset + transferred) > dio->i_size))
 			transferred = dio->i_size - offset;
 		/* ignore EFAULT if some IO has been done */
@@ -286,7 +290,7 @@ 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 && op_is_write(dio->opf) &&
 	    dio->inode->i_mapping->nrpages) {
 		err = invalidate_inode_pages2_range(dio->inode->i_mapping,
 					offset >> PAGE_SHIFT,
@@ -305,7 +309,7 @@ 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 && op_is_write(dio->opf))
 			ret = generic_write_sync(dio->iocb, ret);
 		dio->iocb->ki_complete(dio->iocb, ret);
 	}
@@ -353,7 +357,7 @@ static void dio_bio_end_aio(struct bio *bio)
 		 */
 		if (dio->result)
 			defer_completion = dio->defer_completion ||
-					   (dio->op == REQ_OP_WRITE &&
+					   (op_is_write(dio->opf) &&
 					    dio->inode->i_mapping->nrpages);
 		if (defer_completion) {
 			INIT_WORK(&dio->complete_work, dio_aio_complete_work);
@@ -396,7 +400,7 @@ 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;
@@ -426,7 +430,7 @@ 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 && op_is_read(dio->opf) && dio->should_dirty)
 		bio_set_pages_dirty(bio);
 
 	dio->bio_disk = bio->bi_bdev->bd_disk;
@@ -492,7 +496,7 @@ 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;
+	bool should_dirty = op_is_read(dio->opf) && dio->should_dirty;
 
 	if (err) {
 		if (err == BLK_STS_AGAIN && (bio->bi_opf & REQ_NOWAIT))
@@ -653,7 +657,7 @@ 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 = op_is_write(dio->opf);
 		if (dio->flags & DIO_SKIP_HOLES) {
 			i_size = i_size_read(dio->inode);
 			if (i_size && fs_startblk <= (i_size - 1) >> i_blkbits)
@@ -804,7 +808,7 @@ submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page,
 	int ret = 0;
 	int boundary = sdio->boundary;	/* dio_send_cur_page may clear it */
 
-	if (dio->op == REQ_OP_WRITE) {
+	if (op_is_write(dio->opf)) {
 		/*
 		 * Read accounting is performed in submit_bio()
 		 */
@@ -992,7 +996,7 @@ 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 (op_is_write(dio->opf)) {
 					put_page(page);
 					return -ENOTBLK;
 				}
@@ -1196,12 +1200,11 @@ 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;
 	}
 
 	/*