iov_iter: Use accessor function

Use accessor functions to access an iterator's type and direction.  This
allows for the possibility of using some other method of determining the
type of iterator than if-chains with bitwise-AND conditions.

Signed-off-by: David Howells <[email protected]>

Author: dhowells

block/bio.c

@@ -1255,7 +1255,7 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
 	/*
 	 * success
 	 */
-	if (((iter->type & WRITE) && (!map_data || !map_data->null_mapped)) ||
+	if ((iov_iter_rw(iter) == WRITE && (!map_data || !map_data->null_mapped)) ||
 	    (map_data && map_data->from_user)) {
 		ret = bio_copy_from_iter(bio, iter);
 		if (ret)

fs/block_dev.c

@@ -349,7 +349,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 
 	dio->size = 0;
 	dio->multi_bio = false;
-	dio->should_dirty = is_read && (iter->type == ITER_IOVEC);
+	dio->should_dirty = is_read && iter_is_iovec(iter);
 
 	blk_start_plug(&plug);
 	for (;;) {

fs/ceph/file.c

@@ -658,7 +658,7 @@ static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *to,
 	if (ret < 0)
 		return ret;
 
-	if (unlikely(to->type & ITER_PIPE)) {
+	if (unlikely(iov_iter_is_pipe(to))) {
 		size_t page_off;
 		ret = iov_iter_get_pages_alloc(to, &pages, len,
 					       &page_off);

fs/cifs/file.c

@@ -2990,7 +2990,7 @@ cifs_readdata_to_iov(struct cifs_readdata *rdata, struct iov_iter *iter)
 		size_t copy = min_t(size_t, remaining, PAGE_SIZE);
 		size_t written;
 
-		if (unlikely(iter->type & ITER_PIPE)) {
+		if (unlikely(iov_iter_is_pipe(iter))) {
 			void *addr = kmap_atomic(page);
 
 			written = copy_to_iter(addr, copy, iter);
@@ -3302,7 +3302,7 @@ ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
 	if (!is_sync_kiocb(iocb))
 		ctx->iocb = iocb;
 
-	if (to->type == ITER_IOVEC)
+	if (iter_is_iovec(to))
 		ctx->should_dirty = true;
 
 	rc = setup_aio_ctx_iter(ctx, to, READ);

fs/cifs/misc.c

@@ -786,7 +786,7 @@ setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw)
 	struct page **pages = NULL;
 	struct bio_vec *bv = NULL;
 
-	if (iter->type & ITER_KVEC) {
+	if (iov_iter_is_kvec(iter)) {
 		memcpy(&ctx->iter, iter, sizeof(struct iov_iter));
 		ctx->len = count;
 		iov_iter_advance(iter, count);

fs/cifs/smbdirect.c

@@ -2054,14 +2054,22 @@ int smbd_recv(struct smbd_connection *info, struct msghdr *msg)
 
 	info->smbd_recv_pending++;
 
-	switch (msg->msg_iter.type) {
-	case READ | ITER_KVEC:
+	if (iov_iter_rw(&msg->msg_iter) == WRITE) {
+		/* It's a bug in upper layer to get there */
+		cifs_dbg(VFS, "CIFS: invalid msg iter dir %u\n",
+			 iov_iter_rw(&msg->msg_iter));
+		rc = -EINVAL;
+		goto out;
+	}
+
+	switch (iov_iter_type(&msg->msg_iter)) {
+	case ITER_KVEC:
 		buf = msg->msg_iter.kvec->iov_base;
 		to_read = msg->msg_iter.kvec->iov_len;
 		rc = smbd_recv_buf(info, buf, to_read);
 		break;
 
-	case READ | ITER_BVEC:
+	case ITER_BVEC:
 		page = msg->msg_iter.bvec->bv_page;
 		page_offset = msg->msg_iter.bvec->bv_offset;
 		to_read = msg->msg_iter.bvec->bv_len;
@@ -2071,10 +2079,11 @@ int smbd_recv(struct smbd_connection *info, struct msghdr *msg)
 	default:
 		/* It's a bug in upper layer to get there */
 		cifs_dbg(VFS, "CIFS: invalid msg type %d\n",
-			msg->msg_iter.type);
+			 iov_iter_type(&msg->msg_iter));
 		rc = -EINVAL;
 	}
 
+out:
 	info->smbd_recv_pending--;
 	wake_up(&info->wait_smbd_recv_pending);
 

fs/direct-io.c

@@ -1313,7 +1313,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
 	spin_lock_init(&dio->bio_lock);
 	dio->refcount = 1;
 
-	dio->should_dirty = (iter->type == ITER_IOVEC);
+	dio->should_dirty = iter_is_iovec(iter) && iov_iter_rw(iter) == READ;
 	sdio.iter = iter;
 	sdio.final_block_in_request = end >> blkbits;
 

fs/fuse/file.c

@@ -1271,7 +1271,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
 	ssize_t ret = 0;
 
 	/* Special case for kernel I/O: can copy directly into the buffer */
-	if (ii->type & ITER_KVEC) {
+	if (iov_iter_is_kvec(ii)) {
 		unsigned long user_addr = fuse_get_user_addr(ii);
 		size_t frag_size = fuse_get_frag_size(ii, *nbytesp);
 

fs/iomap.c

@@ -1795,7 +1795,7 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 		if (pos >= dio->i_size)
 			goto out_free_dio;
 
-		if (iter->type == ITER_IOVEC)
+		if (iter_is_iovec(iter) && iov_iter_rw(iter) == READ)
 			dio->flags |= IOMAP_DIO_DIRTY;
 	} else {
 		flags |= IOMAP_WRITE;

include/linux/uio.h

@@ -21,7 +21,7 @@ struct kvec {
 	size_t iov_len;
 };
 
-enum {
+enum iter_type {
 	ITER_IOVEC = 0,
 	ITER_KVEC = 2,
 	ITER_BVEC = 4,
@@ -47,6 +47,36 @@ struct iov_iter {
 	};
 };
 
+static inline enum iter_type iov_iter_type(const struct iov_iter *i)
+{
+	return i->type & ~(READ | WRITE);
+}
+
+static inline bool iter_is_iovec(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_IOVEC;
+}
+
+static inline bool iov_iter_is_kvec(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_KVEC;
+}
+
+static inline bool iov_iter_is_bvec(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_BVEC;
+}
+
+static inline bool iov_iter_is_pipe(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_PIPE;
+}
+
+static inline unsigned char iov_iter_rw(const struct iov_iter *i)
+{
+	return i->type & (READ | WRITE);
+}
+
 /*
  * Total number of bytes covered by an iovec.
  *
@@ -74,7 +104,8 @@ static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
 }
 
 #define iov_for_each(iov, iter, start)				\
-	if (!((start).type & (ITER_BVEC | ITER_PIPE)))		\
+	if (iov_iter_type(start) == ITER_IOVEC ||		\
+	    iov_iter_type(start) == ITER_KVEC)			\
 	for (iter = (start);					\
 	     (iter).count &&					\
 	     ((iov = iov_iter_iovec(&(iter))), 1);		\
@@ -202,19 +233,6 @@ static inline size_t iov_iter_count(const struct iov_iter *i)
 	return i->count;
 }
 
-static inline bool iter_is_iovec(const struct iov_iter *i)
-{
-	return !(i->type & (ITER_BVEC | ITER_KVEC | ITER_PIPE));
-}
-
-/*
- * Get one of READ or WRITE out of iter->type without any other flags OR'd in
- * with it.
- *
- * The ?: is just for type safety.
- */
-#define iov_iter_rw(i) ((0 ? (struct iov_iter *)0 : (i))->type & (READ | WRITE))
-
 /*
  * Cap the iov_iter by given limit; note that the second argument is
  * *not* the new size - it's upper limit for such.  Passing it a value