use less confusing names for iov_iter direction initializers

READ/WRITE proved to be actively confusing - the meanings are
"data destination, as used with read(2)" and "data source, as
used with write(2)", but people keep interpreting those as
"we read data from it" and "we write data to it", i.e. exactly
the wrong way.

Call them ITER_DEST and ITER_SOURCE - at least that is harder
to misinterpret...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

31 files changed, 72 insertions, 72 deletions

diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index 47b9a1122f34..a19891015f19 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -40,7 +40,7 @@ static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
 	size_t len = subreq->len   - subreq->transferred;
 	int total, err;
 
-	iov_iter_xarray(&to, READ, &rreq->mapping->i_pages, pos, len);
+	iov_iter_xarray(&to, ITER_DEST, &rreq->mapping->i_pages, pos, len);
 
 	total = p9_client_read(fid, pos, &to, &err);
 
@@ -172,7 +172,7 @@ static int v9fs_vfs_write_folio_locked(struct folio *folio)
 
 	len = min_t(loff_t, i_size - start, len);
 
-	iov_iter_xarray(&from, WRITE, &folio_mapping(folio)->i_pages, start, len);
+	iov_iter_xarray(&from, ITER_SOURCE, &folio_mapping(folio)->i_pages, start, len);
 
 	/* We should have writeback_fid always set */
 	BUG_ON(!v9inode->writeback_fid);
diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
index 000fbaae9b18..3bb95adc9619 100644
--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -109,7 +109,7 @@ static int v9fs_dir_readdir(struct file *file, struct dir_context *ctx)
 			struct iov_iter to;
 			int n;
 
-			iov_iter_kvec(&to, READ, &kvec, 1, buflen);
+			iov_iter_kvec(&to, ITER_DEST, &kvec, 1, buflen);
 			n = p9_client_read(file->private_data, ctx->pos, &to,
 					   &err);
 			if (err)
diff --git a/fs/9p/xattr.c b/fs/9p/xattr.c
index 1f9298a4bd42..2807bb63f780 100644
--- a/fs/9p/xattr.c
+++ b/fs/9p/xattr.c
@@ -24,7 +24,7 @@ ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
 	struct iov_iter to;
 	int err;
 
-	iov_iter_kvec(&to, READ, &kvec, 1, buffer_size);
+	iov_iter_kvec(&to, ITER_DEST, &kvec, 1, buffer_size);
 
 	attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
 	if (IS_ERR(attr_fid)) {
@@ -109,7 +109,7 @@ int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
 	struct iov_iter from;
 	int retval, err;
 
-	iov_iter_kvec(&from, WRITE, &kvec, 1, value_len);
+	iov_iter_kvec(&from, ITER_SOURCE, &kvec, 1, value_len);
 
 	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
 		 name, value_len, flags);
diff --git a/fs/afs/cmservice.c b/fs/afs/cmservice.c
index 0a090d614e76..7dcd59693a0c 100644
--- a/fs/afs/cmservice.c
+++ b/fs/afs/cmservice.c
@@ -298,7 +298,7 @@ static int afs_deliver_cb_callback(struct afs_call *call)
 		if (call->count2 != call->count && call->count2 != 0)
 			return afs_protocol_error(call, afs_eproto_cb_count);
 		call->iter = &call->def_iter;
-		iov_iter_discard(&call->def_iter, READ, call->count2 * 3 * 4);
+		iov_iter_discard(&call->def_iter, ITER_DEST, call->count2 * 3 * 4);
 		call->unmarshall++;
 
 		fallthrough;
diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 230c2d19116d..104df2964225 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -305,7 +305,7 @@ expand:
 	req->actual_len = i_size; /* May change */
 	req->len = nr_pages * PAGE_SIZE; /* We can ask for more than there is */
 	req->data_version = dvnode->status.data_version; /* May change */
-	iov_iter_xarray(&req->def_iter, READ, &dvnode->netfs.inode.i_mapping->i_pages,
+	iov_iter_xarray(&req->def_iter, ITER_DEST, &dvnode->netfs.inode.i_mapping->i_pages,
 			0, i_size);
 	req->iter = &req->def_iter;
 
diff --git a/fs/afs/file.c b/fs/afs/file.c
index d1cfb235c4b9..2eeab57df133 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -324,7 +324,7 @@ static void afs_issue_read(struct netfs_io_subrequest *subreq)
 	fsreq->vnode	= vnode;
 	fsreq->iter	= &fsreq->def_iter;
 
-	iov_iter_xarray(&fsreq->def_iter, READ,
+	iov_iter_xarray(&fsreq->def_iter, ITER_DEST,
 			&fsreq->vnode->netfs.inode.i_mapping->i_pages,
 			fsreq->pos, fsreq->len);
 
@@ -346,7 +346,7 @@ static int afs_symlink_read_folio(struct file *file, struct folio *folio)
 	fsreq->len	= folio_size(folio);
 	fsreq->vnode	= vnode;
 	fsreq->iter	= &fsreq->def_iter;
-	iov_iter_xarray(&fsreq->def_iter, READ, &folio->mapping->i_pages,
+	iov_iter_xarray(&fsreq->def_iter, ITER_DEST, &folio->mapping->i_pages,
 			fsreq->pos, fsreq->len);
 
 	ret = afs_fetch_data(fsreq->vnode, fsreq);
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 723d162078a3..9ba7b68375c9 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -1301,7 +1301,7 @@ static inline void afs_extract_begin(struct afs_call *call, void *buf, size_t si
 	call->iov_len = size;
 	call->kvec[0].iov_base = buf;
 	call->kvec[0].iov_len = size;
-	iov_iter_kvec(&call->def_iter, READ, call->kvec, 1, size);
+	iov_iter_kvec(&call->def_iter, ITER_DEST, call->kvec, 1, size);
 }
 
 static inline void afs_extract_to_tmp(struct afs_call *call)
@@ -1319,7 +1319,7 @@ static inline void afs_extract_to_tmp64(struct afs_call *call)
 static inline void afs_extract_discard(struct afs_call *call, size_t size)
 {
 	call->iov_len = size;
-	iov_iter_discard(&call->def_iter, READ, size);
+	iov_iter_discard(&call->def_iter, ITER_DEST, size);
 }
 
 static inline void afs_extract_to_buf(struct afs_call *call, size_t size)
diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index eccc3cd0cb70..c62939e5ea1f 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -359,7 +359,7 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
 
 	msg.msg_name		= NULL;
 	msg.msg_namelen		= 0;
-	iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, call->request_size);
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, iov, 1, call->request_size);
 	msg.msg_control		= NULL;
 	msg.msg_controllen	= 0;
 	msg.msg_flags		= MSG_WAITALL | (call->write_iter ? MSG_MORE : 0);
@@ -400,7 +400,7 @@ error_do_abort:
 					RX_USER_ABORT, ret, "KSD");
 	} else {
 		len = 0;
-		iov_iter_kvec(&msg.msg_iter, READ, NULL, 0, 0);
+		iov_iter_kvec(&msg.msg_iter, ITER_DEST, NULL, 0, 0);
 		rxrpc_kernel_recv_data(call->net->socket, rxcall,
 				       &msg.msg_iter, &len, false,
 				       &call->abort_code, &call->service_id);
@@ -485,7 +485,7 @@ static void afs_deliver_to_call(struct afs_call *call)
 	       ) {
 		if (state == AFS_CALL_SV_AWAIT_ACK) {
 			len = 0;
-			iov_iter_kvec(&call->def_iter, READ, NULL, 0, 0);
+			iov_iter_kvec(&call->def_iter, ITER_DEST, NULL, 0, 0);
 			ret = rxrpc_kernel_recv_data(call->net->socket,
 						     call->rxcall, &call->def_iter,
 						     &len, false, &remote_abort,
@@ -822,7 +822,7 @@ void afs_send_empty_reply(struct afs_call *call)
 
 	msg.msg_name		= NULL;
 	msg.msg_namelen		= 0;
-	iov_iter_kvec(&msg.msg_iter, WRITE, NULL, 0, 0);
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, NULL, 0, 0);
 	msg.msg_control		= NULL;
 	msg.msg_controllen	= 0;
 	msg.msg_flags		= 0;
@@ -862,7 +862,7 @@ void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len)
 	iov[0].iov_len		= len;
 	msg.msg_name		= NULL;
 	msg.msg_namelen		= 0;
-	iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, len);
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, iov, 1, len);
 	msg.msg_control		= NULL;
 	msg.msg_controllen	= 0;
 	msg.msg_flags		= 0;
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 9ebdd36eaf2f..08fd456dde67 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -609,7 +609,7 @@ static ssize_t afs_write_back_from_locked_folio(struct address_space *mapping,
 		 */
 		afs_write_to_cache(vnode, start, len, i_size, caching);
 
-		iov_iter_xarray(&iter, WRITE, &mapping->i_pages, start, len);
+		iov_iter_xarray(&iter, ITER_SOURCE, &mapping->i_pages, start, len);
 		ret = afs_store_data(vnode, &iter, start, false);
 	} else {
 		_debug("write discard %x @%llx [%llx]", len, start, i_size);
@@ -1000,7 +1000,7 @@ int afs_launder_folio(struct folio *folio)
 		bv[0].bv_page = &folio->page;
 		bv[0].bv_offset = f;
 		bv[0].bv_len = t - f;
-		iov_iter_bvec(&iter, WRITE, bv, 1, bv[0].bv_len);
+		iov_iter_bvec(&iter, ITER_SOURCE, bv, 1, bv[0].bv_len);
 
 		trace_afs_folio_dirty(vnode, tracepoint_string("launder"), folio);
 		ret = afs_store_data(vnode, &iter, folio_pos(folio) + f, true);
diff --git a/fs/aio.c b/fs/aio.c
index 5b2ff20ad322..562916d85cba 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1552,7 +1552,7 @@ static int aio_read(struct kiocb *req, const struct iocb *iocb,
 	if (unlikely(!file->f_op->read_iter))
 		return -EINVAL;
 
-	ret = aio_setup_rw(READ, iocb, &iovec, vectored, compat, &iter);
+	ret = aio_setup_rw(ITER_DEST, iocb, &iovec, vectored, compat, &iter);
 	if (ret < 0)
 		return ret;
 	ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
@@ -1580,7 +1580,7 @@ static int aio_write(struct kiocb *req, const struct iocb *iocb,
 	if (unlikely(!file->f_op->write_iter))
 		return -EINVAL;
 
-	ret = aio_setup_rw(WRITE, iocb, &iovec, vectored, compat, &iter);
+	ret = aio_setup_rw(ITER_SOURCE, iocb, &iovec, vectored, compat, &iter);
 	if (ret < 0)
 		return ret;
 	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index d5dd8bed1488..a59c884c2cb0 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -5283,7 +5283,7 @@ static int btrfs_ioctl_encoded_read(struct file *file, void __user *argp,
 		goto out_acct;
 	}
 
-	ret = import_iovec(READ, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
+	ret = import_iovec(ITER_DEST, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
 			   &iov, &iter);
 	if (ret < 0)
 		goto out_acct;
@@ -5382,7 +5382,7 @@ static int btrfs_ioctl_encoded_write(struct file *file, void __user *argp, bool
 	if (args.len > args.unencoded_len - args.unencoded_offset)
 		goto out_acct;
 
-	ret = import_iovec(WRITE, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
+	ret = import_iovec(ITER_SOURCE, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
 			   &iov, &iter);
 	if (ret < 0)
 		goto out_acct;
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index dcf701b05cc1..61f47debec5a 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -288,7 +288,7 @@ static bool ceph_netfs_issue_op_inline(struct netfs_io_subrequest *subreq)
 	}
 
 	len = min_t(size_t, iinfo->inline_len - subreq->start, subreq->len);
-	iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages, subreq->start, len);
+	iov_iter_xarray(&iter, ITER_DEST, &rreq->mapping->i_pages, subreq->start, len);
 	err = copy_to_iter(iinfo->inline_data + subreq->start, len, &iter);
 	if (err == 0)
 		err = -EFAULT;
@@ -327,7 +327,7 @@ static void ceph_netfs_issue_read(struct netfs_io_subrequest *subreq)
 	}
 
 	dout("%s: pos=%llu orig_len=%zu len=%llu\n", __func__, subreq->start, subreq->len, len);
-	iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages, subreq->start, len);
+	iov_iter_xarray(&iter, ITER_DEST, &rreq->mapping->i_pages, subreq->start, len);
 	err = iov_iter_get_pages_alloc2(&iter, &pages, len, &page_off);
 	if (err < 0) {
 		dout("%s: iov_ter_get_pages_alloc returned %d\n", __func__, err);
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 04fd34557de8..6f9580defb2b 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1161,7 +1161,7 @@ static void ceph_aio_complete_req(struct ceph_osd_request *req)
 				aio_req->total_len = rc + zlen;
 			}
 
-			iov_iter_bvec(&i, READ, osd_data->bvec_pos.bvecs,
+			iov_iter_bvec(&i, ITER_DEST, osd_data->bvec_pos.bvecs,
 				      osd_data->num_bvecs, len);
 			iov_iter_advance(&i, rc);
 			iov_iter_zero(zlen, &i);
@@ -1400,7 +1400,7 @@ ceph_direct_read_write(struct kiocb *iocb, struct iov_iter *iter,
 				int zlen = min_t(size_t, len - ret,
 						 size - pos - ret);
 
-				iov_iter_bvec(&i, READ, bvecs, num_pages, len);
+				iov_iter_bvec(&i, ITER_DEST, bvecs, num_pages, len);
 				iov_iter_advance(&i, ret);
 				iov_iter_zero(zlen, &i);
 				ret += zlen;
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 9db9527c61cf..e80252a83225 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -759,7 +759,7 @@ cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
 {
 	struct msghdr smb_msg = {};
 	struct kvec iov = {.iov_base = buf, .iov_len = to_read};
-	iov_iter_kvec(&smb_msg.msg_iter, READ, &iov, 1, to_read);
+	iov_iter_kvec(&smb_msg.msg_iter, ITER_DEST, &iov, 1, to_read);
 
 	return cifs_readv_from_socket(server, &smb_msg);
 }
@@ -774,7 +774,7 @@ cifs_discard_from_socket(struct TCP_Server_Info *server, size_t to_read)
 	 *  and cifs_readv_from_socket sets msg_control and msg_controllen
 	 *  so little to initialize in struct msghdr
 	 */
-	iov_iter_discard(&smb_msg.msg_iter, READ, to_read);
+	iov_iter_discard(&smb_msg.msg_iter, ITER_DEST, to_read);
 
 	return cifs_readv_from_socket(server, &smb_msg);
 }
@@ -786,7 +786,7 @@ cifs_read_page_from_socket(struct TCP_Server_Info *server, struct page *page,
 	struct msghdr smb_msg = {};
 	struct bio_vec bv = {
 		.bv_page = page, .bv_len = to_read, .bv_offset = page_offset};
-	iov_iter_bvec(&smb_msg.msg_iter, READ, &bv, 1, to_read);
+	iov_iter_bvec(&smb_msg.msg_iter, ITER_DEST, &bv, 1, to_read);
 	return cifs_readv_from_socket(server, &smb_msg);
 }
 
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index cd9698209930..209dfc06fd6d 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3532,7 +3532,7 @@ static ssize_t __cifs_writev(
 		ctx->iter = *from;
 		ctx->len = len;
 	} else {
-		rc = setup_aio_ctx_iter(ctx, from, WRITE);
+		rc = setup_aio_ctx_iter(ctx, from, ITER_SOURCE);
 		if (rc) {
 			kref_put(&ctx->refcount, cifs_aio_ctx_release);
 			return rc;
@@ -4276,7 +4276,7 @@ static ssize_t __cifs_readv(
 		ctx->iter = *to;
 		ctx->len = len;
 	} else {
-		rc = setup_aio_ctx_iter(ctx, to, READ);
+		rc = setup_aio_ctx_iter(ctx, to, ITER_DEST);
 		if (rc) {
 			kref_put(&ctx->refcount, cifs_aio_ctx_release);
 			return rc;
diff --git a/fs/cifs/fscache.c b/fs/cifs/fscache.c
index a1751b956318..f6f3a6b75601 100644
--- a/fs/cifs/fscache.c
+++ b/fs/cifs/fscache.c
@@ -150,7 +150,7 @@ static int fscache_fallback_read_page(struct inode *inode, struct page *page)
 	bvec[0].bv_page		= page;
 	bvec[0].bv_offset	= 0;
 	bvec[0].bv_len		= PAGE_SIZE;
-	iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
+	iov_iter_bvec(&iter, ITER_DEST, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
 
 	ret = fscache_begin_read_operation(&cres, cookie);
 	if (ret < 0)
@@ -180,7 +180,7 @@ static int fscache_fallback_write_page(struct inode *inode, struct page *page,
 	bvec[0].bv_page		= page;
 	bvec[0].bv_offset	= 0;
 	bvec[0].bv_len		= PAGE_SIZE;
-	iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
+	iov_iter_bvec(&iter, ITER_SOURCE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
 
 	ret = fscache_begin_write_operation(&cres, cookie);
 	if (ret < 0)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index bfaafd02fb1f..32b3877b538a 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -4723,13 +4723,13 @@ handle_read_data(struct TCP_Server_Info *server, struct mid_q_entry *mid,
 			return 0;
 		}
 
-		iov_iter_bvec(&iter, WRITE, bvec, npages, data_len);
+		iov_iter_bvec(&iter, ITER_SOURCE, bvec, npages, data_len);
 	} else if (buf_len >= data_offset + data_len) {
 		/* read response payload is in buf */
 		WARN_ONCE(npages > 0, "read data can be either in buf or in pages");
 		iov.iov_base = buf + data_offset;
 		iov.iov_len = data_len;
-		iov_iter_kvec(&iter, WRITE, &iov, 1, data_len);
+		iov_iter_kvec(&iter, ITER_SOURCE, &iov, 1, data_len);
 	} else {
 		/* read response payload cannot be in both buf and pages */
 		WARN_ONCE(1, "buf can not contain only a part of read data");
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 575fa8f58342..3851d0aaa288 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -347,7 +347,7 @@ __smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 			.iov_base = &rfc1002_marker,
 			.iov_len  = 4
 		};
-		iov_iter_kvec(&smb_msg.msg_iter, WRITE, &hiov, 1, 4);
+		iov_iter_kvec(&smb_msg.msg_iter, ITER_SOURCE, &hiov, 1, 4);
 		rc = smb_send_kvec(server, &smb_msg, &sent);
 		if (rc < 0)
 			goto unmask;
@@ -368,7 +368,7 @@ __smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 			size += iov[i].iov_len;
 		}
 
-		iov_iter_kvec(&smb_msg.msg_iter, WRITE, iov, n_vec, size);
+		iov_iter_kvec(&smb_msg.msg_iter, ITER_SOURCE, iov, n_vec, size);
 
 		rc = smb_send_kvec(server, &smb_msg, &sent);
 		if (rc < 0)
@@ -384,7 +384,7 @@ __smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 			rqst_page_get_length(&rqst[j], i, &bvec.bv_len,
 					     &bvec.bv_offset);
 
-			iov_iter_bvec(&smb_msg.msg_iter, WRITE,
+			iov_iter_bvec(&smb_msg.msg_iter, ITER_SOURCE,
 				      &bvec, 1, bvec.bv_len);
 			rc = smb_send_kvec(server, &smb_msg, &sent);
 			if (rc < 0)
diff --git a/fs/coredump.c b/fs/coredump.c
index 7bad7785e8e6..095ed821c8ac 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -853,7 +853,7 @@ static int dump_emit_page(struct coredump_params *cprm, struct page *page)
 	if (dump_interrupted())
 		return 0;
 	pos = file->f_pos;
-	iov_iter_bvec(&iter, WRITE, &bvec, 1, PAGE_SIZE);
+	iov_iter_bvec(&iter, ITER_SOURCE, &bvec, 1, PAGE_SIZE);
 	n = __kernel_write_iter(cprm->file, &iter, &pos);
 	if (n != PAGE_SIZE)
 		return 0;
diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index af5ed6b9c54d..4c837be3b6e3 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -194,7 +194,7 @@ static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,
 
 		atomic_inc(&rreq->nr_outstanding);
 
-		iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages,
+		iov_iter_xarray(&iter, ITER_DEST, &rreq->mapping->i_pages,
 				start + done, subreq->len);
 
 		ret = fscache_read(cres, subreq->start, &iter,
@@ -290,7 +290,7 @@ static int erofs_fscache_data_read(struct address_space *mapping,
 		if (IS_ERR(src))
 			return PTR_ERR(src);
 
-		iov_iter_xarray(&iter, READ, &mapping->i_pages, pos, PAGE_SIZE);
+		iov_iter_xarray(&iter, ITER_DEST, &mapping->i_pages, pos, PAGE_SIZE);
 		if (copy_to_iter(src + offset, size, &iter) != size) {
 			erofs_put_metabuf(&buf);
 			return -EFAULT;
@@ -302,7 +302,7 @@ static int erofs_fscache_data_read(struct address_space *mapping,
 
 	if (!(map.m_flags & EROFS_MAP_MAPPED)) {
 		count = len;
-		iov_iter_xarray(&iter, READ, &mapping->i_pages, pos, count);
+		iov_iter_xarray(&iter, ITER_DEST, &mapping->i_pages, pos, count);
 		iov_iter_zero(count, &iter);
 		return count;
 	}
diff --git a/fs/fscache/io.c b/fs/fscache/io.c
index 3af3b08a9bb3..0d2b8dec8f82 100644
--- a/fs/fscache/io.c
+++ b/fs/fscache/io.c
@@ -286,7 +286,7 @@ void __fscache_write_to_cache(struct fscache_cookie *cookie,
 	 * taken into account.
 	 */
 
-	iov_iter_xarray(&iter, WRITE, &mapping->i_pages, start, len);
+	iov_iter_xarray(&iter, ITER_SOURCE, &mapping->i_pages, start, len);
 	fscache_write(cres, start, &iter, fscache_wreq_done, wreq);
 	return;
 
diff --git a/fs/fuse/ioctl.c b/fs/fuse/ioctl.c
index 61d8afcb10a3..fcce94ace2c2 100644
--- a/fs/fuse/ioctl.c
+++ b/fs/fuse/ioctl.c
@@ -255,7 +255,7 @@ long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
 		ap.args.in_pages = true;
 
 		err = -EFAULT;
-		iov_iter_init(&ii, WRITE, in_iov, in_iovs, in_size);
+		iov_iter_init(&ii, ITER_SOURCE, in_iov, in_iovs, in_size);
 		for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
 			c = copy_page_from_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
 			if (c != PAGE_SIZE && iov_iter_count(&ii))
@@ -324,7 +324,7 @@ long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
 		goto out;
 
 	err = -EFAULT;
-	iov_iter_init(&ii, READ, out_iov, out_iovs, transferred);
+	iov_iter_init(&ii, ITER_DEST, out_iov, out_iovs, transferred);
 	for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
 		c = copy_page_to_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
 		if (c != PAGE_SIZE && iov_iter_count(&ii))
diff --git a/fs/netfs/io.c b/fs/netfs/io.c
index e374767d1b68..7f753380e047 100644
--- a/fs/netfs/io.c
+++ b/fs/netfs/io.c
@@ -23,7 +23,7 @@ static void netfs_clear_unread(struct netfs_io_subrequest *subreq)
 {
 	struct iov_iter iter;
 
-	iov_iter_xarray(&iter, READ, &subreq->rreq->mapping->i_pages,
+	iov_iter_xarray(&iter, ITER_DEST, &subreq->rreq->mapping->i_pages,
 			subreq->start + subreq->transferred,
 			subreq->len   - subreq->transferred);
 	iov_iter_zero(iov_iter_count(&iter), &iter);
@@ -49,7 +49,7 @@ static void netfs_read_from_cache(struct netfs_io_request *rreq,
 	struct iov_iter iter;
 
 	netfs_stat(&netfs_n_rh_read);
-	iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages,
+	iov_iter_xarray(&iter, ITER_DEST, &rreq->mapping->i_pages,
 			subreq->start + subreq->transferred,
 			subreq->len   - subreq->transferred);
 
@@ -208,7 +208,7 @@ static void netfs_rreq_do_write_to_cache(struct netfs_io_request *rreq)
 			continue;
 		}
 
-		iov_iter_xarray(&iter, WRITE, &rreq->mapping->i_pages,
+		iov_iter_xarray(&iter, ITER_SOURCE, &rreq->mapping->i_pages,
 				subreq->start, subreq->len);
 
 		atomic_inc(&rreq->nr_copy_ops);
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index e861d7bae305..e731c00a9fcb 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -252,7 +252,7 @@ static int fscache_fallback_read_page(struct inode *inode, struct page *page)
 	bvec[0].bv_page		= page;
 	bvec[0].bv_offset	= 0;
 	bvec[0].bv_len		= PAGE_SIZE;
-	iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
+	iov_iter_bvec(&iter, ITER_DEST, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
 
 	ret = fscache_begin_read_operation(&cres, cookie);
 	if (ret < 0)
@@ -282,7 +282,7 @@ static int fscache_fallback_write_page(struct inode *inode, struct page *page,
 	bvec[0].bv_page		= page;
 	bvec[0].bv_offset	= 0;
 	bvec[0].bv_len		= PAGE_SIZE;
-	iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
+	iov_iter_bvec(&iter, ITER_SOURCE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
 
 	ret = fscache_begin_write_operation(&cres, cookie);
 	if (ret < 0)
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index f650afedd67f..51f453baa952 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -942,7 +942,7 @@ __be32 nfsd_readv(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	ssize_t host_err;
 
 	trace_nfsd_read_vector(rqstp, fhp, offset, *count);
-	iov_iter_kvec(&iter, READ, vec, vlen, *count);
+	iov_iter_kvec(&iter, ITER_DEST, vec, vlen, *count);
 	host_err = vfs_iter_read(file, &iter, &ppos, 0);
 	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
 }
@@ -1032,7 +1032,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
 	if (stable && !use_wgather)
 		flags |= RWF_SYNC;
 
-	iov_iter_kvec(&iter, WRITE, vec, vlen, *cnt);
+	iov_iter_kvec(&iter, ITER_SOURCE, vec, vlen, *cnt);
 	since = READ_ONCE(file->f_wb_err);
 	if (verf)
 		nfsd_copy_write_verifier(verf, nn);
diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
index f660c0dbdb63..785cabd71d67 100644
--- a/fs/ocfs2/cluster/tcp.c
+++ b/fs/ocfs2/cluster/tcp.c
@@ -900,7 +900,7 @@ static int o2net_recv_tcp_msg(struct socket *sock, void *data, size_t len)
 {
 	struct kvec vec = { .iov_len = len, .iov_base = data, };
 	struct msghdr msg = { .msg_flags = MSG_DONTWAIT, };
-	iov_iter_kvec(&msg.msg_iter, READ, &vec, 1, len);
+	iov_iter_kvec(&msg.msg_iter, ITER_DEST, &vec, 1, len);
 	return sock_recvmsg(sock, &msg, MSG_DONTWAIT);
 }
 
diff --git a/fs/orangefs/inode.c b/fs/orangefs/inode.c
index 7a8c0c6e698d..b3bbb5a5787a 100644
--- a/fs/orangefs/inode.c
+++ b/fs/orangefs/inode.c
@@ -53,7 +53,7 @@ static int orangefs_writepage_locked(struct page *page,
 	bv.bv_len = wlen;
 	bv.bv_offset = off % PAGE_SIZE;
 	WARN_ON(wlen == 0);
-	iov_iter_bvec(&iter, WRITE, &bv, 1, wlen);
+	iov_iter_bvec(&iter, ITER_SOURCE, &bv, 1, wlen);
 
 	ret = wait_for_direct_io(ORANGEFS_IO_WRITE, inode, &off, &iter, wlen,
 	    len, wr, NULL, NULL);
@@ -112,7 +112,7 @@ static int orangefs_writepages_work(struct orangefs_writepages *ow,
 		else
 			ow->bv[i].bv_offset = 0;
 	}
-	iov_iter_bvec(&iter, WRITE, ow->bv, ow->npages, ow->len);
+	iov_iter_bvec(&iter, ITER_SOURCE, ow->bv, ow->npages, ow->len);
 
 	WARN_ON(ow->off >= len);
 	if (ow->off + ow->len > len)
@@ -270,7 +270,7 @@ static void orangefs_readahead(struct readahead_control *rac)
 	offset = readahead_pos(rac);
 	i_pages = &rac->mapping->i_pages;
 
-	iov_iter_xarray(&iter, READ, i_pages, offset, readahead_length(rac));
+	iov_iter_xarray(&iter, ITER_DEST, i_pages, offset, readahead_length(rac));
 
 	/* read in the pages. */
 	if ((ret = wait_for_direct_io(ORANGEFS_IO_READ, inode,
@@ -303,7 +303,7 @@ static int orangefs_read_folio(struct file *file, struct folio *folio)
 	bv.bv_page = &folio->page;
 	bv.bv_len = folio_size(folio);
 	bv.bv_offset = 0;
-	iov_iter_bvec(&iter, READ, &bv, 1, folio_size(folio));
+	iov_iter_bvec(&iter, ITER_DEST, &bv, 1, folio_size(folio));
 
 	ret = wait_for_direct_io(ORANGEFS_IO_READ, inode, &off, &iter,
 			folio_size(folio), inode->i_size, NULL, NULL, file);
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index f2aa86c421f2..5aa527ca6dbe 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -199,7 +199,7 @@ ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
 	struct kvec kvec = { .iov_base = buf, .iov_len = count };
 	struct iov_iter iter;
 
-	iov_iter_kvec(&iter, READ, &kvec, 1, count);
+	iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
 
 	return read_from_oldmem(&iter, count, ppos, false);
 }
@@ -212,7 +212,7 @@ ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos)
 	struct kvec kvec = { .iov_base = buf, .iov_len = count };
 	struct iov_iter iter;
 
-	iov_iter_kvec(&iter, READ, &kvec, 1, count);
+	iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
 
 	return read_from_oldmem(&iter, count, ppos,
 			cc_platform_has(CC_ATTR_MEM_ENCRYPT));
@@ -437,7 +437,7 @@ static vm_fault_t mmap_vmcore_fault(struct vm_fault *vmf)
 		offset = (loff_t) index << PAGE_SHIFT;
 		kvec.iov_base = page_address(page);
 		kvec.iov_len = PAGE_SIZE;
-		iov_iter_kvec(&iter, READ, &kvec, 1, PAGE_SIZE);
+		iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, PAGE_SIZE);
 
 		rc = __read_vmcore(&iter, &offset);
 		if (rc < 0) {
diff --git a/fs/read_write.c b/fs/read_write.c
index 328ce8cf9a85..37c2f28b51e8 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -384,7 +384,7 @@ static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, lo
 
 	init_sync_kiocb(&kiocb, filp);
 	kiocb.ki_pos = (ppos ? *ppos : 0);
-	iov_iter_ubuf(&iter, READ, buf, len);
+	iov_iter_ubuf(&iter, ITER_DEST, buf, len);
 
 	ret = call_read_iter(filp, &kiocb, &iter);
 	BUG_ON(ret == -EIOCBQUEUED);
@@ -424,7 +424,7 @@ ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
 
 	init_sync_kiocb(&kiocb, file);
 	kiocb.ki_pos = pos ? *pos : 0;
-	iov_iter_kvec(&iter, READ, &iov, 1, iov.iov_len);
+	iov_iter_kvec(&iter, ITER_DEST, &iov, 1, iov.iov_len);
 	ret = file->f_op->read_iter(&kiocb, &iter);
 	if (ret > 0) {
 		if (pos)
@@ -486,7 +486,7 @@ static ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t
 
 	init_sync_kiocb(&kiocb, filp);
 	kiocb.ki_pos = (ppos ? *ppos : 0);
-	iov_iter_ubuf(&iter, WRITE, (void __user *)buf, len);
+	iov_iter_ubuf(&iter, ITER_SOURCE, (void __user *)buf, len);
 
 	ret = call_write_iter(filp, &kiocb, &iter);
 	BUG_ON(ret == -EIOCBQUEUED);
@@ -533,7 +533,7 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t
 		.iov_len	= min_t(size_t, count, MAX_RW_COUNT),
 	};
 	struct iov_iter iter;
-	iov_iter_kvec(&iter, WRITE, &iov, 1, iov.iov_len);
+	iov_iter_kvec(&iter, ITER_SOURCE, &iov, 1, iov.iov_len);
 	return __kernel_write_iter(file, &iter, pos);
 }
 /*
@@ -911,7 +911,7 @@ static ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
 	struct iov_iter iter;
 	ssize_t ret;
 
-	ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
+	ret = import_iovec(ITER_DEST, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
 	if (ret >= 0) {
 		ret = do_iter_read(file, &iter, pos, flags);
 		kfree(iov);
@@ -928,7 +928,7 @@ static ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
 	struct iov_iter iter;
 	ssize_t ret;
 
-	ret = import_iovec(WRITE, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
+	ret = import_iovec(ITER_SOURCE, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
 	if (ret >= 0) {
 		file_start_write(file);
 		ret = do_iter_write(file, &iter, pos, flags);
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 9456a2032224..f5fdaf3b1572 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -156,7 +156,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
 	ssize_t ret;
 
 	init_sync_kiocb(&kiocb, file);
-	iov_iter_init(&iter, READ, &iov, 1, size);
+	iov_iter_init(&iter, ITER_DEST, &iov, 1, size);
 
 	kiocb.ki_pos = *ppos;
 	ret = seq_read_iter(&kiocb, &iter);
diff --git a/fs/splice.c b/fs/splice.c
index 0878b852b355..5969b7a1d353 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -303,7 +303,7 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
 	struct kiocb kiocb;
 	int ret;
 
-	iov_iter_pipe(&to, READ, pipe, len);
+	iov_iter_pipe(&to, ITER_DEST, pipe, len);
 	init_sync_kiocb(&kiocb, in);
 	kiocb.ki_pos = *ppos;
 	ret = call_read_iter(in, &kiocb, &to);
@@ -682,7 +682,7 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
 			n++;
 		}
 
-		iov_iter_bvec(&from, WRITE, array, n, sd.total_len - left);
+		iov_iter_bvec(&from, ITER_SOURCE, array, n, sd.total_len - left);
 		ret = vfs_iter_write(out, &from, &sd.pos, 0);
 		if (ret <= 0)
 			break;
@@ -1263,9 +1263,9 @@ static int vmsplice_type(struct fd f, int *type)
 	if (!f.file)
 		return -EBADF;
 	if (f.file->f_mode & FMODE_WRITE) {
-		*type = WRITE;
+		*type = ITER_SOURCE;
 	} else if (f.file->f_mode & FMODE_READ) {
-		*type = READ;
+		*type = ITER_DEST;
 	} else {
 		fdput(f);
 		return -EBADF;
@@ -1314,7 +1314,7 @@ SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, uiov,
 
 	if (!iov_iter_count(&iter))
 		error = 0;
-	else if (iov_iter_rw(&iter) == WRITE)
+	else if (type == ITER_SOURCE)
 		error = vmsplice_to_pipe(f.file, &iter, flags);
 	else
 		error = vmsplice_to_user(f.file, &iter, flags);