9p: switch p9_client_read() to passing struct iov_iter *

... and make it loop

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

1 files changed, 61 insertions, 63 deletions

diff --git a/net/9p/client.c b/net/9p/client.c
index aa38cfeb8615..18583bb89db6 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -1534,79 +1534,77 @@ error:
 EXPORT_SYMBOL(p9_client_unlinkat);
 
 int
-p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,
-                                                                u32 count)
+p9_client_read(struct p9_fid *fid, u64 offset, struct iov_iter *to, int *err)
 {
-        char *dataptr;
+        struct p9_client *clnt = fid->clnt;
         struct p9_req_t *req;
-        struct p9_client *clnt;
-        int err, rsize, non_zc = 0;
-        struct iov_iter to;
-        union {
-                struct kvec kv;
-                struct iovec iov;
-        } v;
-
-        if (data) {
-                v.kv.iov_base = data;
-                v.kv.iov_len = count;
-                iov_iter_kvec(&to, ITER_KVEC | READ, &v.kv, 1, count);
-        } else {
-                v.iov.iov_base = udata;
-                v.iov.iov_len = count;
-                iov_iter_init(&to, READ, &v.iov, 1, count);
-        }
+        int total = 0;
 
         p9_debug(P9_DEBUG_9P, ">>> TREAD fid %d offset %llu %d\n",
-                   fid->fid, (unsigned long long) offset, count);
-        err = 0;
-        clnt = fid->clnt;
-
-        rsize = fid->iounit;
-        if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
-                rsize = clnt->msize - P9_IOHDRSZ;
+                   fid->fid, (unsigned long long) offset, (int)iov_iter_count(to));
+
+        while (iov_iter_count(to)) {
+                int count = iov_iter_count(to);
+                int rsize, non_zc = 0;
+                char *dataptr;
+                        
+                rsize = fid->iounit;
+                if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
+                        rsize = clnt->msize - P9_IOHDRSZ;
 
-        if (count < rsize)
-                rsize = count;
+                if (count < rsize)
+                        rsize = count;
 
-        /* Don't bother zerocopy for small IO (< 1024) */
-        if (clnt->trans_mod->zc_request && rsize > 1024) {
-                /*
-                 * response header len is 11
-                 * PDU Header(7) + IO Size (4)
-                 */
-                req = p9_client_zc_rpc(clnt, P9_TREAD, &to, NULL, rsize, 0,
-                                       11, "dqd", fid->fid,
-                                       offset, rsize);
-        } else {
-                non_zc = 1;
-                req = p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset,
-                                    rsize);
-        }
-        if (IS_ERR(req)) {
-                err = PTR_ERR(req);
-                goto error;
-        }
+                /* Don't bother zerocopy for small IO (< 1024) */
+                if (clnt->trans_mod->zc_request && rsize > 1024) {
+                        /*
+                         * response header len is 11
+                         * PDU Header(7) + IO Size (4)
+                         */
+                        req = p9_client_zc_rpc(clnt, P9_TREAD, to, NULL, rsize,
+                                               0, 11, "dqd", fid->fid,
+                                               offset, rsize);
+                } else {
+                        non_zc = 1;
+                        req = p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset,
+                                            rsize);
+                }
+                if (IS_ERR(req)) {
+                        *err = PTR_ERR(req);
+                        break;
+                }
 
-        err = p9pdu_readf(req->rc, clnt->proto_version, "D", &count, &dataptr);
-        if (err) {
-                trace_9p_protocol_dump(clnt, req->rc);
-                goto free_and_error;
-        }
+                *err = p9pdu_readf(req->rc, clnt->proto_version,
+                                   "D", &count, &dataptr);
+                if (*err) {
+                        trace_9p_protocol_dump(clnt, req->rc);
+                        p9_free_req(clnt, req);
+                        break;
+                }
 
-        p9_debug(P9_DEBUG_9P, "<<< RREAD count %d\n", count);
+                p9_debug(P9_DEBUG_9P, "<<< RREAD count %d\n", count);
+                if (!count) {
+                        p9_free_req(clnt, req);
+                        break;
+                }
 
-        if (non_zc && copy_to_iter(dataptr, count, &to) != count) {
-                err = -EFAULT;
-                goto free_and_error;
+                if (non_zc) {
+                        int n = copy_to_iter(dataptr, count, to);
+                        total += n;
+                        offset += n;
+                        if (n != count) {
+                                *err = -EFAULT;
+                                p9_free_req(clnt, req);
+                                break;
+                        }
+                } else {
+                        iov_iter_advance(to, count);
+                        total += count;
+                        offset += count;
+                }
+                p9_free_req(clnt, req);
         }
-        p9_free_req(clnt, req);
-        return count;
-
-free_and_error:
-        p9_free_req(clnt, req);
-error:
-        return err;
+        return total;
 }
 EXPORT_SYMBOL(p9_client_read);