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iov_iter: Separate type from direction and use accessor functions

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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>
This commit is contained in:
David Howells
2018-10-20 00:57:56 +01:00
parent 00e2370744
commit aa563d7bca
40 changed files with 96 additions and 105 deletions
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6
net/ceph/messenger.c
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@@ -526,7 +526,7 @@ static int ceph_tcp_recvmsg(struct socket *sock, void *buf, size_t len)
if (!buf)
msg.msg_flags |= MSG_TRUNC;
iov_iter_kvec(&msg.msg_iter, READ | ITER_KVEC, &iov, 1, len);
iov_iter_kvec(&msg.msg_iter, READ, &iov, 1, len);
r = sock_recvmsg(sock, &msg, msg.msg_flags);
if (r == -EAGAIN)
r = 0;
@@ -545,7 +545,7 @@ static int ceph_tcp_recvpage(struct socket *sock, struct page *page,
int r;
BUG_ON(page_offset + length > PAGE_SIZE);
iov_iter_bvec(&msg.msg_iter, READ | ITER_BVEC, &bvec, 1, length);
iov_iter_bvec(&msg.msg_iter, READ, &bvec, 1, length);
r = sock_recvmsg(sock, &msg, msg.msg_flags);
if (r == -EAGAIN)
r = 0;
@@ -607,7 +607,7 @@ static int ceph_tcp_sendpage(struct socket *sock, struct page *page,
else
msg.msg_flags |= MSG_EOR; /* superfluous, but what the hell */
iov_iter_bvec(&msg.msg_iter, WRITE | ITER_BVEC, &bvec, 1, size);
iov_iter_bvec(&msg.msg_iter, WRITE, &bvec, 1, size);
ret = sock_sendmsg(sock, &msg);
if (ret == -EAGAIN)
ret = 0;