[nbd] pass iov_iter to nbd_xmit()

... and don't mess with kmap() - just use BVEC_ITER for those parts.

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

1 files changed, 27 insertions, 39 deletions

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 8e63caecdd00..3c2dbe412c02 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -209,13 +209,12 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
 /*
  *  Send or receive packet.
  */
-static int sock_xmit(struct nbd_device *nbd, int index, int send, void *buf,
-                     int size, int msg_flags)
+static int sock_xmit(struct nbd_device *nbd, int index, int send,
+                     struct iov_iter *iter, int msg_flags)
 {
         struct socket *sock = nbd->socks[index]->sock;
         int result;
         struct msghdr msg;
-        struct kvec iov = {.iov_base = buf, .iov_len = size};
         unsigned long pflags = current->flags;
 
         if (unlikely(!sock)) {
@@ -225,8 +224,7 @@ static int sock_xmit(struct nbd_device *nbd, int index, int send, void *buf,
                 return -EINVAL;
         }
 
-        iov_iter_kvec(&msg.msg_iter, (send ? WRITE : READ) | ITER_KVEC,
-                      &iov, 1, size);
+        msg.msg_iter = *iter;
 
         current->flags |= PF_MEMALLOC;
         do {
@@ -254,28 +252,21 @@ static int sock_xmit(struct nbd_device *nbd, int index, int send, void *buf,
         return result;
 }
 
-static inline int sock_send_bvec(struct nbd_device *nbd, int index,
-                                 struct bio_vec *bvec, int flags)
-{
-        int result;
-        void *kaddr = kmap(bvec->bv_page);
-        result = sock_xmit(nbd, index, 1, kaddr + bvec->bv_offset,
-                           bvec->bv_len, flags);
-        kunmap(bvec->bv_page);
-        return result;
-}
-
 /* always call with the tx_lock held */
 static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
 {
         struct request *req = blk_mq_rq_from_pdu(cmd);
         int result, flags;
-        struct nbd_request request;
+        struct nbd_request request = {.magic = htonl(NBD_REQUEST_MAGIC)};
+        struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
+        struct iov_iter from;
         unsigned long size = blk_rq_bytes(req);
         struct bio *bio;
         u32 type;
         u32 tag = blk_mq_unique_tag(req);
 
+        iov_iter_kvec(&from, WRITE | ITER_KVEC, &iov, 1, sizeof(request));
+
         if (req_op(req) == REQ_OP_DISCARD)
                 type = NBD_CMD_TRIM;
         else if (req_op(req) == REQ_OP_FLUSH)
@@ -285,8 +276,6 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
         else
                 type = NBD_CMD_READ;
 
-        memset(&request, 0, sizeof(request));
-        request.magic = htonl(NBD_REQUEST_MAGIC);
         request.type = htonl(type);
         if (type != NBD_CMD_FLUSH) {
                 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
@@ -297,7 +286,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
         dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
                 cmd, nbdcmd_to_ascii(type),
                 (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
-        result = sock_xmit(nbd, index, 1, &request, sizeof(request),
+        result = sock_xmit(nbd, index, 1, &from,
                         (type == NBD_CMD_WRITE) ? MSG_MORE : 0);
         if (result <= 0) {
                 dev_err_ratelimited(disk_to_dev(nbd->disk),
@@ -322,7 +311,9 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
                                 flags = MSG_MORE;
                         dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
                                 cmd, bvec.bv_len);
-                        result = sock_send_bvec(nbd, index, &bvec, flags);
+                        iov_iter_bvec(&from, ITER_BVEC | WRITE,
+                                      &bvec, 1, bvec.bv_len);
+                        result = sock_xmit(nbd, index, 1, &from, flags);
                         if (result <= 0) {
                                 dev_err(disk_to_dev(nbd->disk),
                                         "Send data failed (result %d)\n",
@@ -343,17 +334,6 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
         return 0;
 }
 
-static inline int sock_recv_bvec(struct nbd_device *nbd, int index,
-                                 struct bio_vec *bvec)
-{
-        int result;
-        void *kaddr = kmap(bvec->bv_page);
-        result = sock_xmit(nbd, index, 0, kaddr + bvec->bv_offset,
-                           bvec->bv_len, MSG_WAITALL);
-        kunmap(bvec->bv_page);
-        return result;
-}
-
 /* NULL returned = something went wrong, inform userspace */
 static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
 {
@@ -363,9 +343,12 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
         struct request *req = NULL;
         u16 hwq;
         u32 tag;
+        struct kvec iov = {.iov_base = &reply, .iov_len = sizeof(reply)};
+        struct iov_iter to;
 
         reply.magic = 0;
-        result = sock_xmit(nbd, index, 0, &reply, sizeof(reply), MSG_WAITALL);
+        iov_iter_kvec(&to, READ | ITER_KVEC, &iov, 1, sizeof(reply));
+        result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL);
         if (result <= 0) {
                 if (!test_bit(NBD_DISCONNECTED, &nbd->runtime_flags) &&
                     !test_bit(NBD_DISCONNECT_REQUESTED, &nbd->runtime_flags))
@@ -405,7 +388,9 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
                 struct bio_vec bvec;
 
                 rq_for_each_segment(bvec, req, iter) {
-                        result = sock_recv_bvec(nbd, index, &bvec);
+                        iov_iter_bvec(&to, ITER_BVEC | READ,
+                                      &bvec, 1, bvec.bv_len);
+                        result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL);
                         if (result <= 0) {
                                 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
                                         result);
@@ -645,14 +630,17 @@ static void nbd_parse_flags(struct nbd_device *nbd, struct block_device *bdev)
 
 static void send_disconnects(struct nbd_device *nbd)
 {
-        struct nbd_request request = {};
+        struct nbd_request request = {
+                .magic = htonl(NBD_REQUEST_MAGIC),
+                .type = htonl(NBD_CMD_DISC),
+        };
+        struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
+        struct iov_iter from;
         int i, ret;
 
-        request.magic = htonl(NBD_REQUEST_MAGIC);
-        request.type = htonl(NBD_CMD_DISC);
-
         for (i = 0; i < nbd->num_connections; i++) {
-                ret = sock_xmit(nbd, i, 1, &request, sizeof(request), 0);
+                iov_iter_kvec(&from, WRITE | ITER_KVEC, &iov, 1, sizeof(request));
+                ret = sock_xmit(nbd, i, 1, &from, 0);
                 if (ret <= 0)
                         dev_err(disk_to_dev(nbd->disk),
                                 "Send disconnect failed %d\n", ret);