iov_iter: Separate type from direction and use accessor functions

In the iov_iter struct, separate the iterator type from the iterator
direction and use accessor functions to access them in most places.

Convert a bunch of places to use switch-statements to access them rather
then chains of bitwise-AND statements.  This makes it easier to add further
iterator types.  Also, this can be more efficient as to implement a switch
of small contiguous integers, the compiler can use ~50% fewer compare
instructions than it has to use bitwise-and instructions.

Further, cease passing the iterator type into the iterator setup function.
The iterator function can set that itself.  Only the direction is required.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index e1cbdfdb7c68..0bcbcc20f769 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -65,7 +65,7 @@ static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page)
 	if (retval == 0)
 		return retval;
 
-	iov_iter_bvec(&to, ITER_BVEC | READ, &bvec, 1, PAGE_SIZE);
+	iov_iter_bvec(&to, READ, &bvec, 1, PAGE_SIZE);
 
 	retval = p9_client_read(fid, page_offset(page), &to, &err);
 	if (err) {
@@ -175,7 +175,7 @@ static int v9fs_vfs_writepage_locked(struct page *page)
 	bvec.bv_page = page;
 	bvec.bv_offset = 0;
 	bvec.bv_len = len;
-	iov_iter_bvec(&from, ITER_BVEC | WRITE, &bvec, 1, len);
+	iov_iter_bvec(&from, WRITE, &bvec, 1, len);
 
 	/* We should have writeback_fid always set */
 	BUG_ON(!v9inode->writeback_fid);