// SPDX-License-Identifier: GPL-2.0
#include <linux/ceph/ceph_debug.h>

#include <linux/bvec.h>
#include <linux/crc32c.h>
#include <linux/net.h>
#include <linux/socket.h>
#include <net/sock.h>

#include <linux/ceph/ceph_features.h>
#include <linux/ceph/decode.h>
#include <linux/ceph/libceph.h>
#include <linux/ceph/messenger.h>

/* static tag bytes (protocol control messages) */
static char tag_msg = CEPH_MSGR_TAG_MSG;
static char tag_ack = CEPH_MSGR_TAG_ACK;
static char tag_keepalive = CEPH_MSGR_TAG_KEEPALIVE;
static char tag_keepalive2 = CEPH_MSGR_TAG_KEEPALIVE2;

/*
 * If @buf is NULL, discard up to @len bytes.
 */
static int ceph_tcp_recvmsg(struct socket *sock, void *buf, size_t len)
{
        struct kvec iov = {buf, len};
        struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL };
        int r;

        if (!buf)
                msg.msg_flags |= MSG_TRUNC;

        iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, len);
        r = sock_recvmsg(sock, &msg, msg.msg_flags);
        if (r == -EAGAIN)
                r = 0;
        return r;
}

static int ceph_tcp_recvpage(struct socket *sock, struct page *page,
                     int page_offset, size_t length)
{
        struct bio_vec bvec;
        struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL };
        int r;

        BUG_ON(page_offset + length > PAGE_SIZE);
        bvec_set_page(&bvec, page, length, page_offset);
        iov_iter_bvec(&msg.msg_iter, ITER_DEST, &bvec, 1, length);
        r = sock_recvmsg(sock, &msg, msg.msg_flags);
        if (r == -EAGAIN)
                r = 0;
        return r;
}

/*
 * write something.  @more is true if caller will be sending more data
 * shortly.
 */
static int ceph_tcp_sendmsg(struct socket *sock, struct kvec *iov,
                            size_t kvlen, size_t len, bool more)
{
        struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL };
        int r;

        if (more)
                msg.msg_flags |= MSG_MORE;
        else
                msg.msg_flags |= MSG_EOR;  /* superfluous, but what the hell */

        r = kernel_sendmsg(sock, &msg, iov, kvlen, len);
        if (r == -EAGAIN)
                r = 0;
        return r;
}

/*
 * @more: MSG_MORE or 0.
 */
static int ceph_tcp_sendpage(struct socket *sock, struct page *page,
                             int offset, size_t size, int more)
{
        struct msghdr msg = {
                .msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL | more,
        };
        struct bio_vec bvec;
        int ret;

        /*
         * MSG_SPLICE_PAGES cannot properly handle pages with page_count == 0,
         * we need to fall back to sendmsg if that's the case.
         *
         * Same goes for slab pages: skb_can_coalesce() allows
         * coalescing neighboring slab objects into a single frag which
         * triggers one of hardened usercopy checks.
         */
        if (sendpage_ok(page))
                msg.msg_flags |= MSG_SPLICE_PAGES;

        bvec_set_page(&bvec, page, size, offset);
        iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);

        ret = sock_sendmsg(sock, &msg);
        if (ret == -EAGAIN)
                ret = 0;

        return ret;
}

static void con_out_kvec_reset(struct ceph_connection *con)
{
        BUG_ON(con->v1.out_skip);

        con->v1.out_kvec_left = 0;
        con->v1.out_kvec_bytes = 0;
        con->v1.out_kvec_cur = &con->v1.out_kvec[0];
}

static void con_out_kvec_add(struct ceph_connection *con,
                                size_t size, void *data)
{
        int index = con->v1.out_kvec_left;

        BUG_ON(con->v1.out_skip);
        BUG_ON(index >= ARRAY_SIZE(con->v1.out_kvec));

        con->v1.out_kvec[index].iov_len = size;
        con->v1.out_kvec[index].iov_base = data;
        con->v1.out_kvec_left++;
        con->v1.out_kvec_bytes += size;
}

/*
 * Chop off a kvec from the end.  Return residual number of bytes for
 * that kvec, i.e. how many bytes would have been written if the kvec
 * hadn't been nuked.
 */
static int con_out_kvec_skip(struct ceph_connection *con)
{
        int skip = 0;

        if (con->v1.out_kvec_bytes > 0) {
                skip = con->v1.out_kvec_cur[con->v1.out_kvec_left - 1].iov_len;
                BUG_ON(con->v1.out_kvec_bytes < skip);
                BUG_ON(!con->v1.out_kvec_left);
                con->v1.out_kvec_bytes -= skip;
                con->v1.out_kvec_left--;
        }

        return skip;
}

static size_t sizeof_footer(struct ceph_connection *con)
{
        return (con->peer_features & CEPH_FEATURE_MSG_AUTH) ?
            sizeof(struct ceph_msg_footer) :
            sizeof(struct ceph_msg_footer_old);
}

static void prepare_message_data(struct ceph_msg *msg, u32 data_len)
{
        /* Initialize data cursor if it's not a sparse read */
        u64 len = msg->sparse_read_total ? : data_len;

        ceph_msg_data_cursor_init(&msg->cursor, msg, len);
}

/*
 * Prepare footer for currently outgoing message, and finish things
 * off.  Assumes out_kvec* are already valid.. we just add on to the end.
 */
static void prepare_write_message_footer(struct ceph_connection *con,
                                         struct ceph_msg *m)
{
        m->footer.flags |= CEPH_MSG_FOOTER_COMPLETE;

        dout("prepare_write_message_footer %p\n", con);
        con_out_kvec_add(con, sizeof_footer(con), &m->footer);
        if (con->peer_features & CEPH_FEATURE_MSG_AUTH) {
                if (con->ops->sign_message)
                        con->ops->sign_message(m);
                else
                        m->footer.sig = 0;
        } else {
                m->old_footer.flags = m->footer.flags;
        }
        con->v1.out_more = m->more_to_follow;
        con->v1.out_msg_done = true;
}

/*
 * Prepare headers for the next outgoing message.
 */
static void prepare_write_message(struct ceph_connection *con,
                                  struct ceph_msg *m)
{
        u32 crc;

        con_out_kvec_reset(con);
        con->v1.out_msg_done = false;

        /* Sneak an ack in there first?  If we can get it into the same
         * TCP packet that's a good thing. */
        if (con->in_seq > con->in_seq_acked) {
                con->in_seq_acked = con->in_seq;
                con_out_kvec_add(con, sizeof (tag_ack), &tag_ack);
                con->v1.out_temp_ack = cpu_to_le64(con->in_seq_acked);
                con_out_kvec_add(con, sizeof(con->v1.out_temp_ack),
                        &con->v1.out_temp_ack);
        }

        dout("prepare_write_message %p seq %lld type %d len %d+%d+%zd\n",
             m, con->out_seq, le16_to_cpu(m->hdr.type),
             le32_to_cpu(m->hdr.front_len), le32_to_cpu(m->hdr.middle_len),
             m->data_length);
        WARN_ON(m->front.iov_len != le32_to_cpu(m->hdr.front_len));
        WARN_ON(m->data_length != le32_to_cpu(m->hdr.data_len));

        /* tag + hdr + front + middle */
        con_out_kvec_add(con, sizeof (tag_msg), &tag_msg);
        con_out_kvec_add(con, sizeof(con->v1.out_hdr), &con->v1.out_hdr);
        con_out_kvec_add(con, m->front.iov_len, m->front.iov_base);

        if (m->middle)
                con_out_kvec_add(con, m->middle->vec.iov_len,
                        m->middle->vec.iov_base);

        /* fill in hdr crc and finalize hdr */
        crc = crc32c(0, &m->hdr, offsetof(struct ceph_msg_header, crc));
        m->hdr.crc = cpu_to_le32(crc);
        memcpy(&con->v1.out_hdr, &m->hdr, sizeof(con->v1.out_hdr));

        /* fill in front and middle crc, footer */
        crc = crc32c(0, m->front.iov_base, m->front.iov_len);
        m->footer.front_crc = cpu_to_le32(crc);
        if (m->middle) {
                crc = crc32c(0, m->middle->vec.iov_base,
                                m->middle->vec.iov_len);
                m->footer.middle_crc = cpu_to_le32(crc);
        } else
                m->footer.middle_crc = 0;
        dout("%s front_crc %u middle_crc %u\n", __func__,
             le32_to_cpu(m->footer.front_crc),
             le32_to_cpu(m->footer.middle_crc));
        m->footer.flags = 0;

        /* is there a data payload? */
        m->footer.data_crc = 0;
        if (m->data_length) {
                prepare_message_data(m, m->data_length);
                con->v1.out_more = 1;  /* data + footer will follow */
        } else {
                /* no, queue up footer too and be done */
                prepare_write_message_footer(con, m);
        }

        ceph_con_flag_set(con, CEPH_CON_F_WRITE_PENDING);
}

/*
 * Prepare an ack.
 */
static void prepare_write_ack(struct ceph_connection *con)
{
        dout("prepare_write_ack %p %llu -> %llu\n", con,
             con->in_seq_acked, con->in_seq);
        con->in_seq_acked = con->in_seq;

        con_out_kvec_reset(con);

        con_out_kvec_add(con, sizeof (tag_ack), &tag_ack);

        con->v1.out_temp_ack = cpu_to_le64(con->in_seq_acked);
        con_out_kvec_add(con, sizeof(con->v1.out_temp_ack),
                         &con->v1.out_temp_ack);

        con->v1.out_more = 1;  /* more will follow.. eventually.. */
        ceph_con_flag_set(con, CEPH_CON_F_WRITE_PENDING);
}

/*
 * Prepare to share the seq during handshake
 */
static void prepare_write_seq(struct ceph_connection *con)
{
        dout("prepare_write_seq %p %llu -> %llu\n", con,
             con->in_seq_acked, con->in_seq);
        con->in_seq_acked = con->in_seq;

        con_out_kvec_reset(con);

        con->v1.out_temp_ack = cpu_to_le64(con->in_seq_acked);
        con_out_kvec_add(con, sizeof(con->v1.out_temp_ack),
                         &con->v1.out_temp_ack);

        ceph_con_flag_set(con, CEPH_CON_F_WRITE_PENDING);
}

/*
 * Prepare to write keepalive byte.
 */
static void prepare_write_keepalive(struct ceph_connection *con)
{
        dout("prepare_write_keepalive %p\n", con);
        con_out_kvec_reset(con);
        if (con->peer_features & CEPH_FEATURE_MSGR_KEEPALIVE2) {
                struct timespec64 now;

                ktime_get_real_ts64(&now);
                con_out_kvec_add(con, sizeof(tag_keepalive2), &tag_keepalive2);
                ceph_encode_timespec64(&con->v1.out_temp_keepalive2, &now);
                con_out_kvec_add(con, sizeof(con->v1.out_temp_keepalive2),
                                 &con->v1.out_temp_keepalive2);
        } else {
                con_out_kvec_add(con, sizeof(tag_keepalive), &tag_keepalive);
        }
        ceph_con_flag_set(con, CEPH_CON_F_WRITE_PENDING);
}

/*
 * Connection negotiation.
 */

static int get_connect_authorizer(struct ceph_connection *con)
{
        struct ceph_auth_handshake *auth;
        int auth_proto;

        if (!con->ops->get_authorizer) {
                con->v1.auth = NULL;
                con->v1.out_connect.authorizer_protocol = CEPH_AUTH_UNKNOWN;
                con->v1.out_connect.authorizer_len = 0;
                return 0;
        }

        auth = con->ops->get_authorizer(con, &auth_proto, con->v1.auth_retry);
        if (IS_ERR(auth))
                return PTR_ERR(auth);

        con->v1.auth = auth;
        con->v1.out_connect.authorizer_protocol = cpu_to_le32(auth_proto);
        con->v1.out_connect.authorizer_len =
                cpu_to_le32(auth->authorizer_buf_len);
        return 0;
}

/*
 * We connected to a peer and are saying hello.
 */
static void prepare_write_banner(struct ceph_connection *con)
{
        con_out_kvec_add(con, strlen(CEPH_BANNER), CEPH_BANNER);
        con_out_kvec_add(con, sizeof (con->msgr->my_enc_addr),
                                        &con->msgr->my_enc_addr);

        con->v1.out_more = 0;
        ceph_con_flag_set(con, CEPH_CON_F_WRITE_PENDING);
}

static void __prepare_write_connect(struct ceph_connection *con)
{
        con_out_kvec_add(con, sizeof(con->v1.out_connect),
                         &con->v1.out_connect);
        if (con->v1.auth)
                con_out_kvec_add(con, con->v1.auth->authorizer_buf_len,
                                 con->v1.auth->authorizer_buf);

        con->v1.out_more = 0;
        ceph_con_flag_set(con, CEPH_CON_F_WRITE_PENDING);
}

static int prepare_write_connect(struct ceph_connection *con)
{
        unsigned int global_seq = ceph_get_global_seq(con->msgr, 0);
        int proto;
        int ret;

        switch (con->peer_name.type) {
        case CEPH_ENTITY_TYPE_MON:
                proto = CEPH_MONC_PROTOCOL;
                break;
        case CEPH_ENTITY_TYPE_OSD:
                proto = CEPH_OSDC_PROTOCOL;
                break;
        case CEPH_ENTITY_TYPE_MDS:
                proto = CEPH_MDSC_PROTOCOL;
                break;
        default:
                BUG();
        }

        dout("prepare_write_connect %p cseq=%d gseq=%d proto=%d\n", con,
             con->v1.connect_seq, global_seq, proto);

        con->v1.out_connect.features =
                cpu_to_le64(from_msgr(con->msgr)->supported_features);
        con->v1.out_connect.host_type = cpu_to_le32(CEPH_ENTITY_TYPE_CLIENT);
        con->v1.out_connect.connect_seq = cpu_to_le32(con->v1.connect_seq);
        con->v1.out_connect.global_seq = cpu_to_le32(global_seq);
        con->v1.out_connect.protocol_version = cpu_to_le32(proto);
        con->v1.out_connect.flags = 0;

        ret = get_connect_authorizer(con);
        if (ret)
                return ret;

        __prepare_write_connect(con);
        return 0;
}

/*
 * write as much of pending kvecs to the socket as we can.
 *  1 -> done
 *  0 -> socket full, but more to do
 * <0 -> error
 */
static int write_partial_kvec(struct ceph_connection *con)
{
        int ret;

        dout("write_partial_kvec %p %d left\n", con, con->v1.out_kvec_bytes);
        while (con->v1.out_kvec_bytes > 0) {
                ret = ceph_tcp_sendmsg(con->sock, con->v1.out_kvec_cur,
                                       con->v1.out_kvec_left,
                                       con->v1.out_kvec_bytes,
                                       con->v1.out_more);
                if (ret <= 0)
                        goto out;
                con->v1.out_kvec_bytes -= ret;
                if (!con->v1.out_kvec_bytes)
                        break;            /* done */

                /* account for full iov entries consumed */
                while (ret >= con->v1.out_kvec_cur->iov_len) {
                        BUG_ON(!con->v1.out_kvec_left);
                        ret -= con->v1.out_kvec_cur->iov_len;
                        con->v1.out_kvec_cur++;
                        con->v1.out_kvec_left--;
                }
                /* and for a partially-consumed entry */
                if (ret) {
                        con->v1.out_kvec_cur->iov_len -= ret;
                        con->v1.out_kvec_cur->iov_base += ret;
                }
        }
        con->v1.out_kvec_left = 0;
        ret = 1;
out:
        dout("write_partial_kvec %p %d left in %d kvecs ret = %d\n", con,
             con->v1.out_kvec_bytes, con->v1.out_kvec_left, ret);
        return ret;  /* done! */
}

/*
 * Write as much message data payload as we can.  If we finish, queue
 * up the footer.
 *  1 -> done, footer is now queued in out_kvec[].
 *  0 -> socket full, but more to do
 * <0 -> error
 */
static int write_partial_message_data(struct ceph_connection *con,
                                      struct ceph_msg *msg)
{
        struct ceph_msg_data_cursor *cursor = &msg->cursor;
        bool do_datacrc = !ceph_test_opt(from_msgr(con->msgr), NOCRC);
        u32 crc;

        dout("%s %p msg %p\n", __func__, con, msg);

        if (!msg->num_data_items)
                return -EINVAL;

        /*
         * Iterate through each page that contains data to be
         * written, and send as much as possible for each.
         *
         * If we are calculating the data crc (the default), we will
         * need to map the page.  If we have no pages, they have
         * been revoked, so use the zero page.
         */
        crc = do_datacrc ? le32_to_cpu(msg->footer.data_crc) : 0;
        while (cursor->total_resid) {
                struct page *page;
                size_t page_offset;
                size_t length;
                int ret;

                if (!cursor->resid) {
                        ceph_msg_data_advance(cursor, 0);
                        continue;
                }

                page = ceph_msg_data_next(cursor, &page_offset, &length);
                ret = ceph_tcp_sendpage(con->sock, page, page_offset, length,
                                        MSG_MORE);
                if (ret <= 0) {
                        if (do_datacrc)
                                msg->footer.data_crc = cpu_to_le32(crc);

                        return ret;
                }
                if (do_datacrc && cursor->need_crc)
                        crc = ceph_crc32c_page(crc, page, page_offset, length);
                ceph_msg_data_advance(cursor, (size_t)ret);
        }

        dout("%s %p msg %p done\n", __func__, con, msg);

        /* prepare and queue up footer, too */
        if (do_datacrc)
                msg->footer.data_crc = cpu_to_le32(crc);
        else
                msg->footer.flags |= CEPH_MSG_FOOTER_NOCRC;
        con_out_kvec_reset(con);
        prepare_write_message_footer(con, msg);

        return 1;       /* must return > 0 to indicate success */
}

/*
 * write some zeros
 */
static int write_partial_skip(struct ceph_connection *con)
{
        int ret;

        dout("%s %p %d left\n", __func__, con, con->v1.out_skip);
        while (con->v1.out_skip > 0) {
                size_t size = min(con->v1.out_skip, (int)PAGE_SIZE);

                ret = ceph_tcp_sendpage(con->sock, ceph_zero_page, 0, size,
                                        MSG_MORE);
                if (ret <= 0)
                        goto out;
                con->v1.out_skip -= ret;
        }
        ret = 1;
out:
        return ret;
}

/*
 * Prepare to read connection handshake, or an ack.
 */
static void prepare_read_banner(struct ceph_connection *con)
{
        dout("prepare_read_banner %p\n", con);
        con->v1.in_base_pos = 0;
}

static void prepare_read_connect(struct ceph_connection *con)
{
        dout("prepare_read_connect %p\n", con);
        con->v1.in_base_pos = 0;
}

static void prepare_read_ack(struct ceph_connection *con)
{
        dout("prepare_read_ack %p\n", con);
        con->v1.in_base_pos = 0;
}

static void prepare_read_seq(struct ceph_connection *con)
{
        dout("prepare_read_seq %p\n", con);
        con->v1.in_base_pos = 0;
        con->v1.in_tag = CEPH_MSGR_TAG_SEQ;
}

static void prepare_read_tag(struct ceph_connection *con)
{
        dout("prepare_read_tag %p\n", con);
        con->v1.in_base_pos = 0;
        con->v1.in_tag = CEPH_MSGR_TAG_READY;
}

static void prepare_read_keepalive_ack(struct ceph_connection *con)
{
        dout("prepare_read_keepalive_ack %p\n", con);
        con->v1.in_base_pos = 0;
}

/*
 * Prepare to read a message.
 */
static int prepare_read_message(struct ceph_connection *con)
{
        dout("prepare_read_message %p\n", con);
        BUG_ON(con->in_msg != NULL);
        con->v1.in_base_pos = 0;
        con->in_front_crc = con->in_middle_crc = con->in_data_crc = 0;
        return 0;
}

static int read_partial(struct ceph_connection *con,
                        int end, int size, void *object)
{
        while (con->v1.in_base_pos < end) {
                int left = end - con->v1.in_base_pos;
                int have = size - left;
                int ret = ceph_tcp_recvmsg(con->sock, object + have, left);
                if (ret <= 0)
                        return ret;
                con->v1.in_base_pos += ret;
        }
        return 1;
}

/*
 * Read all or part of the connect-side handshake on a new connection
 */
static int read_partial_banner(struct ceph_connection *con)
{
        int size;
        int end;
        int ret;

        dout("read_partial_banner %p at %d\n", con, con->v1.in_base_pos);

        /* peer's banner */
        size = strlen(CEPH_BANNER);
        end = size;
        ret = read_partial(con, end, size, con->v1.in_banner);
        if (ret <= 0)
                goto out;

        size = sizeof(con->v1.actual_peer_addr);
        end += size;
        ret = read_partial(con, end, size, &con->v1.actual_peer_addr);
        if (ret <= 0)
                goto out;
        ceph_decode_banner_addr(&con->v1.actual_peer_addr);

        size = sizeof(con->v1.peer_addr_for_me);
        end += size;
        ret = read_partial(con, end, size, &con->v1.peer_addr_for_me);
        if (ret <= 0)
                goto out;
        ceph_decode_banner_addr(&con->v1.peer_addr_for_me);

out:
        return ret;
}

static int read_partial_connect(struct ceph_connection *con)
{
        int size;
        int end;
        int ret;

        dout("read_partial_connect %p at %d\n", con, con->v1.in_base_pos);

        size = sizeof(con->v1.in_reply);
        end = size;
        ret = read_partial(con, end, size, &con->v1.in_reply);
        if (ret <= 0)
                goto out;

        if (con->v1.auth) {
                size = le32_to_cpu(con->v1.in_reply.authorizer_len);
                if (size > con->v1.auth->authorizer_reply_buf_len) {
                        pr_err("authorizer reply too big: %d > %zu\n", size,
                               con->v1.auth->authorizer_reply_buf_len);
                        ret = -EINVAL;
                        goto out;
                }

                end += size;
                ret = read_partial(con, end, size,
                                   con->v1.auth->authorizer_reply_buf);
                if (ret <= 0)
                        goto out;
        }

        dout("read_partial_connect %p tag %d, con_seq = %u, g_seq = %u\n",
             con, con->v1.in_reply.tag,
             le32_to_cpu(con->v1.in_reply.connect_seq),
             le32_to_cpu(con->v1.in_reply.global_seq));
out:
        return ret;
}

/*
 * Verify the hello banner looks okay.
 */
static int verify_hello(struct ceph_connection *con)
{
        if (memcmp(con->v1.in_banner, CEPH_BANNER, strlen(CEPH_BANNER))) {
                pr_err("connect to %s got bad banner\n",
                       ceph_pr_addr(&con->peer_addr));
                con->error_msg = "protocol error, bad banner";
                return -1;
        }
        return 0;
}

static int process_banner(struct ceph_connection *con)
{
        struct ceph_entity_addr *my_addr = &con->msgr->inst.addr;

        dout("process_banner on %p\n", con);

        if (verify_hello(con) < 0)
                return -1;

        /*
         * Make sure the other end is who we wanted.  note that the other
         * end may not yet know their ip address, so if it's 0.0.0.0, give
         * them the benefit of the doubt.
         */
        if (memcmp(&con->peer_addr, &con->v1.actual_peer_addr,
                   sizeof(con->peer_addr)) != 0 &&
            !(ceph_addr_is_blank(&con->v1.actual_peer_addr) &&
              con->v1.actual_peer_addr.nonce == con->peer_addr.nonce)) {
                pr_warn("wrong peer, want %s/%u, got %s/%u\n",
                        ceph_pr_addr(&con->peer_addr),
                        le32_to_cpu(con->peer_addr.nonce),
                        ceph_pr_addr(&con->v1.actual_peer_addr),
                        le32_to_cpu(con->v1.actual_peer_addr.nonce));
                con->error_msg = "wrong peer at address";
                return -1;
        }

        /*
         * did we learn our address?
         */
        if (ceph_addr_is_blank(my_addr)) {
                memcpy(&my_addr->in_addr,
                       &con->v1.peer_addr_for_me.in_addr,
                       sizeof(con->v1.peer_addr_for_me.in_addr));
                ceph_addr_set_port(my_addr, 0);
                ceph_encode_my_addr(con->msgr);
                dout("process_banner learned my addr is %s\n",
                     ceph_pr_addr(my_addr));
        }

        return 0;
}

static int process_connect(struct ceph_connection *con)
{
        u64 sup_feat = from_msgr(con->msgr)->supported_features;
        u64 req_feat = from_msgr(con->msgr)->required_features;
        u64 server_feat = le64_to_cpu(con->v1.in_reply.features);
        int ret;

        dout("process_connect on %p tag %d\n", con, con->v1.in_tag);

        if (con->v1.auth) {
                int len = le32_to_cpu(con->v1.in_reply.authorizer_len);

                /*
                 * Any connection that defines ->get_authorizer()
                 * should also define ->add_authorizer_challenge() and
                 * ->verify_authorizer_reply().
                 *
                 * See get_connect_authorizer().
                 */
                if (con->v1.in_reply.tag ==
                                CEPH_MSGR_TAG_CHALLENGE_AUTHORIZER) {
                        ret = con->ops->add_authorizer_challenge(
                                con, con->v1.auth->authorizer_reply_buf, len);
                        if (ret < 0)
                                return ret;

                        con_out_kvec_reset(con);
                        __prepare_write_connect(con);
                        prepare_read_connect(con);
                        return 0;
                }

                if (len) {
                        ret = con->ops->verify_authorizer_reply(con);
                        if (ret < 0) {
                                con->error_msg = "bad authorize reply";
                                return ret;
                        }
                }
        }

        switch (con->v1.in_reply.tag) {
        case CEPH_MSGR_TAG_FEATURES:
                pr_err("%s%lld %s feature set mismatch,"
                       " my %llx < server's %llx, missing %llx\n",
                       ENTITY_NAME(con->peer_name),
                       ceph_pr_addr(&con->peer_addr),
                       sup_feat, server_feat, server_feat & ~sup_feat);
                con->error_msg = "missing required protocol features";
                return -1;

        case CEPH_MSGR_TAG_BADPROTOVER:
                pr_err("%s%lld %s protocol version mismatch,"
                       " my %d != server's %d\n",
                       ENTITY_NAME(con->peer_name),
                       ceph_pr_addr(&con->peer_addr),
                       le32_to_cpu(con->v1.out_connect.protocol_version),
                       le32_to_cpu(con->v1.in_reply.protocol_version));
                con->error_msg = "protocol version mismatch";
                return -1;

        case CEPH_MSGR_TAG_BADAUTHORIZER:
                con->v1.auth_retry++;
                dout("process_connect %p got BADAUTHORIZER attempt %d\n", con,
                     con->v1.auth_retry);
                if (con->v1.auth_retry == 2) {
                        con->error_msg = "connect authorization failure";
                        return -1;
                }
                con_out_kvec_reset(con);
                ret = prepare_write_connect(con);
                if (ret < 0)
                        return ret;
                prepare_read_connect(con);
                break;

        case CEPH_MSGR_TAG_RESETSESSION:
                /*
                 * If we connected with a large connect_seq but the peer
                 * has no record of a session with us (no connection, or
                 * connect_seq == 0), they will send RESETSESION to indicate
                 * that they must have reset their session, and may have
                 * dropped messages.
                 */
                dout("process_connect got RESET peer seq %u\n",
                     le32_to_cpu(con->v1.in_reply.connect_seq));
                pr_info("%s%lld %s session reset\n",
                        ENTITY_NAME(con->peer_name),
                        ceph_pr_addr(&con->peer_addr));
                ceph_con_reset_session(con);
                con_out_kvec_reset(con);
                ret = prepare_write_connect(con);
                if (ret < 0)
                        return ret;
                prepare_read_connect(con);

                /* Tell ceph about it. */
                mutex_unlock(&con->mutex);
                if (con->ops->peer_reset)
                        con->ops->peer_reset(con);
                mutex_lock(&con->mutex);
                if (con->state != CEPH_CON_S_V1_CONNECT_MSG)
                        return -EAGAIN;
                break;

        case CEPH_MSGR_TAG_RETRY_SESSION:
                /*
                 * If we sent a smaller connect_seq than the peer has, try
                 * again with a larger value.
                 */
                dout("process_connect got RETRY_SESSION my seq %u, peer %u\n",
                     le32_to_cpu(con->v1.out_connect.connect_seq),
                     le32_to_cpu(con->v1.in_reply.connect_seq));
                con->v1.connect_seq = le32_to_cpu(con->v1.in_reply.connect_seq);
                con_out_kvec_reset(con);
                ret = prepare_write_connect(con);
                if (ret < 0)
                        return ret;
                prepare_read_connect(con);
                break;

        case CEPH_MSGR_TAG_RETRY_GLOBAL:
                /*
                 * If we sent a smaller global_seq than the peer has, try
                 * again with a larger value.
                 */
                dout("process_connect got RETRY_GLOBAL my %u peer_gseq %u\n",
                     con->v1.peer_global_seq,
                     le32_to_cpu(con->v1.in_reply.global_seq));
                ceph_get_global_seq(con->msgr,
                                    le32_to_cpu(con->v1.in_reply.global_seq));
                con_out_kvec_reset(con);
                ret = prepare_write_connect(con);
                if (ret < 0)
                        return ret;
                prepare_read_connect(con);
                break;

        case CEPH_MSGR_TAG_SEQ:
        case CEPH_MSGR_TAG_READY:
                if (req_feat & ~server_feat) {
                        pr_err("%s%lld %s protocol feature mismatch,"
                               " my required %llx > server's %llx, need %llx\n",
                               ENTITY_NAME(con->peer_name),
                               ceph_pr_addr(&con->peer_addr),
                               req_feat, server_feat, req_feat & ~server_feat);
                        con->error_msg = "missing required protocol features";
                        return -1;
                }

                WARN_ON(con->state != CEPH_CON_S_V1_CONNECT_MSG);
                con->state = CEPH_CON_S_OPEN;
                con->v1.auth_retry = 0;    /* we authenticated; clear flag */
                con->v1.peer_global_seq =
                        le32_to_cpu(con->v1.in_reply.global_seq);
                con->v1.connect_seq++;
                con->peer_features = server_feat;
                dout("process_connect got READY gseq %d cseq %d (%d)\n",
                     con->v1.peer_global_seq,
                     le32_to_cpu(con->v1.in_reply.connect_seq),
                     con->v1.connect_seq);
                WARN_ON(con->v1.connect_seq !=
                        le32_to_cpu(con->v1.in_reply.connect_seq));

                if (con->v1.in_reply.flags & CEPH_MSG_CONNECT_LOSSY)
                        ceph_con_flag_set(con, CEPH_CON_F_LOSSYTX);

                con->delay = 0;      /* reset backoff memory */

                if (con->v1.in_reply.tag == CEPH_MSGR_TAG_SEQ) {
                        prepare_write_seq(con);
                        prepare_read_seq(con);
                } else {
                        prepare_read_tag(con);
                }
                break;

        case CEPH_MSGR_TAG_WAIT:
                /*
                 * If there is a connection race (we are opening
                 * connections to each other), one of us may just have
                 * to WAIT.  This shouldn't happen if we are the
                 * client.
                 */
                con->error_msg = "protocol error, got WAIT as client";
                return -1;

        default:
                con->error_msg = "protocol error, garbage tag during connect";
                return -1;
        }
        return 0;
}

/*
 * read (part of) an ack
 */
static int read_partial_ack(struct ceph_connection *con)
{
        int size = sizeof(con->v1.in_temp_ack);
        int end = size;

        return read_partial(con, end, size, &con->v1.in_temp_ack);
}

/*
 * We can finally discard anything that's been acked.
 */
static void process_ack(struct ceph_connection *con)
{
        u64 ack = le64_to_cpu(con->v1.in_temp_ack);

        if (con->v1.in_tag == CEPH_MSGR_TAG_ACK)
                ceph_con_discard_sent(con, ack);
        else
                ceph_con_discard_requeued(con, ack);

        prepare_read_tag(con);
}

static int read_partial_message_chunk(struct ceph_connection *con,
                                      struct kvec *section,
                                      unsigned int sec_len, u32 *crc)
{
        int ret, left;

        BUG_ON(!section);

        while (section->iov_len < sec_len) {
                BUG_ON(section->iov_base == NULL);
                left = sec_len - section->iov_len;
                ret = ceph_tcp_recvmsg(con->sock, (char *)section->iov_base +
                                       section->iov_len, left);
                if (ret <= 0)
                        return ret;
                section->iov_len += ret;
        }
        if (section->iov_len == sec_len)
                *crc = crc32c(*crc, section->iov_base, section->iov_len);

        return 1;
}

static inline int read_partial_message_section(struct ceph_connection *con,
                                               struct kvec *section,
                                               unsigned int sec_len, u32 *crc)
{
        *crc = 0;
        return read_partial_message_chunk(con, section, sec_len, crc);
}

static int read_partial_sparse_msg_extent(struct ceph_connection *con, u32 *crc)
{
        struct ceph_msg_data_cursor *cursor = &con->in_msg->cursor;
        bool do_bounce = ceph_test_opt(from_msgr(con->msgr), RXBOUNCE);

        if (do_bounce && unlikely(!con->bounce_page)) {
                con->bounce_page = alloc_page(GFP_NOIO);
                if (!con->bounce_page) {
                        pr_err("failed to allocate bounce page\n");
                        return -ENOMEM;
                }
        }

        while (cursor->sr_resid > 0) {
                struct page *page, *rpage;
                size_t off, len;
                int ret;

                page = ceph_msg_data_next(cursor, &off, &len);
                rpage = do_bounce ? con->bounce_page : page;

                /* clamp to what remains in extent */
                len = min_t(int, len, cursor->sr_resid);
                ret = ceph_tcp_recvpage(con->sock, rpage, (int)off, len);
                if (ret <= 0)
                        return ret;
                *crc = ceph_crc32c_page(*crc, rpage, off, ret);
                ceph_msg_data_advance(cursor, (size_t)ret);
                cursor->sr_resid -= ret;
                if (do_bounce)
                        memcpy_page(page, off, rpage, off, ret);
        }
        return 1;
}

static int read_partial_sparse_msg_data(struct ceph_connection *con)
{
        struct ceph_msg_data_cursor *cursor = &con->in_msg->cursor;
        bool do_datacrc = !ceph_test_opt(from_msgr(con->msgr), NOCRC);
        u32 crc = 0;
        int ret = 1;

        if (do_datacrc)
                crc = con->in_data_crc;

        while (cursor->total_resid) {
                if (con->v1.in_sr_kvec.iov_base)
                        ret = read_partial_message_chunk(con,
                                                         &con->v1.in_sr_kvec,
                                                         con->v1.in_sr_len,
                                                         &crc);
                else if (cursor->sr_resid > 0)
                        ret = read_partial_sparse_msg_extent(con, &crc);
                if (ret <= 0)
                        break;

                memset(&con->v1.in_sr_kvec, 0, sizeof(con->v1.in_sr_kvec));
                ret = con->ops->sparse_read(con, cursor,
                                (char **)&con->v1.in_sr_kvec.iov_base);
                if (ret <= 0) {
                        ret = ret ? ret : 1;  /* must return > 0 to indicate success */
                        break;
                }
                con->v1.in_sr_len = ret;
        }

        if (do_datacrc)
                con->in_data_crc = crc;

        return ret;
}

static int read_partial_msg_data(struct ceph_connection *con)
{
        struct ceph_msg_data_cursor *cursor = &con->in_msg->cursor;
        bool do_datacrc = !ceph_test_opt(from_msgr(con->msgr), NOCRC);
        struct page *page;
        size_t page_offset;
        size_t length;
        u32 crc = 0;
        int ret;

        if (do_datacrc)
                crc = con->in_data_crc;
        while (cursor->total_resid) {
                if (!cursor->resid) {
                        ceph_msg_data_advance(cursor, 0);
                        continue;
                }

                page = ceph_msg_data_next(cursor, &page_offset, &length);
                ret = ceph_tcp_recvpage(con->sock, page, page_offset, length);
                if (ret <= 0) {
                        if (do_datacrc)
                                con->in_data_crc = crc;

                        return ret;
                }

                if (do_datacrc)
                        crc = ceph_crc32c_page(crc, page, page_offset, ret);
                ceph_msg_data_advance(cursor, (size_t)ret);
        }
        if (do_datacrc)
                con->in_data_crc = crc;

        return 1;       /* must return > 0 to indicate success */
}

static int read_partial_msg_data_bounce(struct ceph_connection *con)
{
        struct ceph_msg_data_cursor *cursor = &con->in_msg->cursor;
        struct page *page;
        size_t off, len;
        u32 crc;
        int ret;

        if (unlikely(!con->bounce_page)) {
                con->bounce_page = alloc_page(GFP_NOIO);
                if (!con->bounce_page) {
                        pr_err("failed to allocate bounce page\n");
                        return -ENOMEM;
                }
        }

        crc = con->in_data_crc;
        while (cursor->total_resid) {
                if (!cursor->resid) {
                        ceph_msg_data_advance(cursor, 0);
                        continue;
                }

                page = ceph_msg_data_next(cursor, &off, &len);
                ret = ceph_tcp_recvpage(con->sock, con->bounce_page, 0, len);
                if (ret <= 0) {
                        con->in_data_crc = crc;
                        return ret;
                }

                crc = crc32c(crc, page_address(con->bounce_page), ret);
                memcpy_to_page(page, off, page_address(con->bounce_page), ret);

                ceph_msg_data_advance(cursor, ret);
        }
        con->in_data_crc = crc;

        return 1;       /* must return > 0 to indicate success */
}

/*
 * read (part of) a message.
 */
static int read_partial_message(struct ceph_connection *con)
{
        struct ceph_msg *m = con->in_msg;
        int size;
        int end;
        int ret;
        unsigned int front_len, middle_len, data_len;
        bool do_datacrc = !ceph_test_opt(from_msgr(con->msgr), NOCRC);
        bool need_sign = (con->peer_features & CEPH_FEATURE_MSG_AUTH);
        u64 seq;
        u32 crc;

        dout("read_partial_message con %p msg %p\n", con, m);

        /* header */
        size = sizeof(con->v1.in_hdr);
        end = size;
        ret = read_partial(con, end, size, &con->v1.in_hdr);
        if (ret <= 0)
                return ret;

        crc = crc32c(0, &con->v1.in_hdr, offsetof(struct ceph_msg_header, crc));
        if (cpu_to_le32(crc) != con->v1.in_hdr.crc) {
                pr_err("read_partial_message bad hdr crc %u != expected %u\n",
                       crc, con->v1.in_hdr.crc);
                return -EBADMSG;
        }

        front_len = le32_to_cpu(con->v1.in_hdr.front_len);
        if (front_len > CEPH_MSG_MAX_FRONT_LEN)
                return -EIO;
        middle_len = le32_to_cpu(con->v1.in_hdr.middle_len);
        if (middle_len > CEPH_MSG_MAX_MIDDLE_LEN)
                return -EIO;
        data_len = le32_to_cpu(con->v1.in_hdr.data_len);
        if (data_len > CEPH_MSG_MAX_DATA_LEN)
                return -EIO;

        /* verify seq# */
        seq = le64_to_cpu(con->v1.in_hdr.seq);
        if ((s64)seq - (s64)con->in_seq < 1) {
                pr_info("skipping %s%lld %s seq %lld expected %lld\n",
                        ENTITY_NAME(con->peer_name),
                        ceph_pr_addr(&con->peer_addr),
                        seq, con->in_seq + 1);
                con->v1.in_base_pos = -front_len - middle_len - data_len -
                                      sizeof_footer(con);
                con->v1.in_tag = CEPH_MSGR_TAG_READY;
                return 1;
        } else if ((s64)seq - (s64)con->in_seq > 1) {
                pr_err("read_partial_message bad seq %lld expected %lld\n",
                       seq, con->in_seq + 1);
                con->error_msg = "bad message sequence # for incoming message";
                return -EBADE;
        }

        /* allocate message? */
        if (!con->in_msg) {
                int skip = 0;

                dout("got hdr type %d front %d data %d\n", con->v1.in_hdr.type,
                     front_len, data_len);
                ret = ceph_con_in_msg_alloc(con, &con->v1.in_hdr, &skip);
                if (ret < 0)
                        return ret;

                BUG_ON((!con->in_msg) ^ skip);
                if (skip) {
                        /* skip this message */
                        dout("alloc_msg said skip message\n");
                        con->v1.in_base_pos = -front_len - middle_len -
                                              data_len - sizeof_footer(con);
                        con->v1.in_tag = CEPH_MSGR_TAG_READY;
                        con->in_seq++;
                        return 1;
                }

                BUG_ON(!con->in_msg);
                BUG_ON(con->in_msg->con != con);
                m = con->in_msg;
                m->front.iov_len = 0;    /* haven't read it yet */
                if (m->middle)
                        m->middle->vec.iov_len = 0;

                /* prepare for data payload, if any */

                if (data_len)
                        prepare_message_data(con->in_msg, data_len);
        }

        /* front */
        ret = read_partial_message_section(con, &m->front, front_len,
                                           &con->in_front_crc);
        if (ret <= 0)
                return ret;

        /* middle */
        if (m->middle) {
                ret = read_partial_message_section(con, &m->middle->vec,
                                                   middle_len,
                                                   &con->in_middle_crc);
                if (ret <= 0)
                        return ret;
        }

        /* (page) data */
        if (data_len) {
                if (!m->num_data_items)
                        return -EIO;

                if (m->sparse_read_total)
                        ret = read_partial_sparse_msg_data(con);
                else if (ceph_test_opt(from_msgr(con->msgr), RXBOUNCE))
                        ret = read_partial_msg_data_bounce(con);
                else
                        ret = read_partial_msg_data(con);
                if (ret <= 0)
                        return ret;
        }

        /* footer */
        size = sizeof_footer(con);
        end += size;
        ret = read_partial(con, end, size, &m->footer);
        if (ret <= 0)
                return ret;

        if (!need_sign) {
                m->footer.flags = m->old_footer.flags;
                m->footer.sig = 0;
        }

        dout("read_partial_message got msg %p %d (%u) + %d (%u) + %d (%u)\n",
             m, front_len, m->footer.front_crc, middle_len,
             m->footer.middle_crc, data_len, m->footer.data_crc);

        /* crc ok? */
        if (con->in_front_crc != le32_to_cpu(m->footer.front_crc)) {
                pr_err("read_partial_message %p front crc %u != exp. %u\n",
                       m, con->in_front_crc, m->footer.front_crc);
                return -EBADMSG;
        }
        if (con->in_middle_crc != le32_to_cpu(m->footer.middle_crc)) {
                pr_err("read_partial_message %p middle crc %u != exp %u\n",
                       m, con->in_middle_crc, m->footer.middle_crc);
                return -EBADMSG;
        }
        if (do_datacrc &&
            (m->footer.flags & CEPH_MSG_FOOTER_NOCRC) == 0 &&
            con->in_data_crc != le32_to_cpu(m->footer.data_crc)) {
                pr_err("read_partial_message %p data crc %u != exp. %u\n", m,
                       con->in_data_crc, le32_to_cpu(m->footer.data_crc));
                return -EBADMSG;
        }

        if (need_sign && con->ops->check_message_signature &&
            con->ops->check_message_signature(m)) {
                pr_err("read_partial_message %p signature check failed\n", m);
                return -EBADMSG;
        }

        return 1; /* done! */
}

static int read_keepalive_ack(struct ceph_connection *con)
{
        struct ceph_timespec ceph_ts;
        size_t size = sizeof(ceph_ts);
        int ret = read_partial(con, size, size, &ceph_ts);
        if (ret <= 0)
                return ret;
        ceph_decode_timespec64(&con->last_keepalive_ack, &ceph_ts);
        prepare_read_tag(con);
        return 1;
}

/*
 * Read what we can from the socket.
 */
int ceph_con_v1_try_read(struct ceph_connection *con)
{
        int ret = -1;

more:
        dout("try_read start %p state %d\n", con, con->state);
        if (con->state != CEPH_CON_S_V1_BANNER &&
            con->state != CEPH_CON_S_V1_CONNECT_MSG &&
            con->state != CEPH_CON_S_OPEN)
                return 0;

        BUG_ON(!con->sock);

        dout("try_read tag %d in_base_pos %d\n", con->v1.in_tag,
             con->v1.in_base_pos);

        if (con->state == CEPH_CON_S_V1_BANNER) {
                ret = read_partial_banner(con);
                if (ret <= 0)
                        goto out;
                ret = process_banner(con);
                if (ret < 0)
                        goto out;

                con->state = CEPH_CON_S_V1_CONNECT_MSG;

                /*
                 * Received banner is good, exchange connection info.
                 * Do not reset out_kvec, as sending our banner raced
                 * with receiving peer banner after connect completed.
                 */
                ret = prepare_write_connect(con);
                if (ret < 0)
                        goto out;
                prepare_read_connect(con);

                /* Send connection info before awaiting response */
                goto out;
        }

        if (con->state == CEPH_CON_S_V1_CONNECT_MSG) {
                ret = read_partial_connect(con);
                if (ret <= 0)
                        goto out;
                ret = process_connect(con);
                if (ret < 0)
                        goto out;
                goto more;
        }

        WARN_ON(con->state != CEPH_CON_S_OPEN);

        if (con->v1.in_base_pos < 0) {
                /*
                 * skipping + discarding content.
                 */
                ret = ceph_tcp_recvmsg(con->sock, NULL, -con->v1.in_base_pos);
                if (ret <= 0)
                        goto out;
                dout("skipped %d / %d bytes\n", ret, -con->v1.in_base_pos);
                con->v1.in_base_pos += ret;
                if (con->v1.in_base_pos)
                        goto more;
        }
        if (con->v1.in_tag == CEPH_MSGR_TAG_READY) {
                /*
                 * what's next?
                 */
                ret = ceph_tcp_recvmsg(con->sock, &con->v1.in_tag, 1);
                if (ret <= 0)
                        goto out;
                dout("try_read got tag %d\n", con->v1.in_tag);
                switch (con->v1.in_tag) {
                case CEPH_MSGR_TAG_MSG:
                        prepare_read_message(con);
                        break;
                case CEPH_MSGR_TAG_ACK:
                        prepare_read_ack(con);
                        break;
                case CEPH_MSGR_TAG_KEEPALIVE2_ACK:
                        prepare_read_keepalive_ack(con);
                        break;
                case CEPH_MSGR_TAG_CLOSE:
                        ceph_con_close_socket(con);
                        con->state = CEPH_CON_S_CLOSED;
                        goto out;
                default:
                        goto bad_tag;
                }
        }
        if (con->v1.in_tag == CEPH_MSGR_TAG_MSG) {
                ret = read_partial_message(con);
                if (ret <= 0) {
                        switch (ret) {
                        case -EBADMSG:
                                con->error_msg = "bad crc/signature";
                                fallthrough;
                        case -EBADE:
                                ret = -EIO;
                                break;
                        case -EIO:
                                con->error_msg = "io error";
                                break;
                        }
                        goto out;
                }
                if (con->v1.in_tag == CEPH_MSGR_TAG_READY)
                        goto more;
                ceph_con_process_message(con);
                if (con->state == CEPH_CON_S_OPEN)
                        prepare_read_tag(con);
                goto more;
        }
        if (con->v1.in_tag == CEPH_MSGR_TAG_ACK ||
            con->v1.in_tag == CEPH_MSGR_TAG_SEQ) {
                /*
                 * the final handshake seq exchange is semantically
                 * equivalent to an ACK
                 */
                ret = read_partial_ack(con);
                if (ret <= 0)
                        goto out;
                process_ack(con);
                goto more;
        }
        if (con->v1.in_tag == CEPH_MSGR_TAG_KEEPALIVE2_ACK) {
                ret = read_keepalive_ack(con);
                if (ret <= 0)
                        goto out;
                goto more;
        }

out:
        dout("try_read done on %p ret %d\n", con, ret);
        return ret;

bad_tag:
        pr_err("try_read bad tag %d\n", con->v1.in_tag);
        con->error_msg = "protocol error, garbage tag";
        ret = -1;
        goto out;
}

/*
 * Write something to the socket.  Called in a worker thread when the
 * socket appears to be writeable and we have something ready to send.
 */
int ceph_con_v1_try_write(struct ceph_connection *con)
{
        struct ceph_msg *msg;
        int ret = 1;

        dout("try_write start %p state %d\n", con, con->state);
        if (con->state != CEPH_CON_S_PREOPEN &&
            con->state != CEPH_CON_S_V1_BANNER &&
            con->state != CEPH_CON_S_V1_CONNECT_MSG &&
            con->state != CEPH_CON_S_OPEN)
                return 0;

        /* open the socket first? */
        if (con->state == CEPH_CON_S_PREOPEN) {
                BUG_ON(con->sock);
                con->state = CEPH_CON_S_V1_BANNER;

                con_out_kvec_reset(con);
                prepare_write_banner(con);
                prepare_read_banner(con);

                BUG_ON(con->in_msg);
                con->v1.in_tag = CEPH_MSGR_TAG_READY;
                dout("try_write initiating connect on %p new state %d\n",
                     con, con->state);
                ret = ceph_tcp_connect(con);
                if (ret < 0) {
                        con->error_msg = "connect error";
                        goto out;
                }
        }

more:
        dout("try_write out_kvec_bytes %d\n", con->v1.out_kvec_bytes);
        BUG_ON(!con->sock);

        /* kvec data queued? */
        if (con->v1.out_kvec_left) {
                ret = write_partial_kvec(con);
                if (ret <= 0)
                        goto out;
        }
        if (con->v1.out_skip) {
                ret = write_partial_skip(con);
                if (ret <= 0)
                        goto out;
        }

        /* msg pages? */
        msg = con->out_msg;
        if (msg) {
                if (con->v1.out_msg_done) {
                        ceph_msg_put(msg);
                        con->out_msg = NULL;   /* we're done with this one */
                        goto do_next;
                }

                ret = write_partial_message_data(con, msg);
                if (ret == 1)
                        goto more;  /* we need to send the footer, too! */
                if (ret == 0)
                        goto out;
                if (ret < 0) {
                        dout("try_write write_partial_message_data err %d\n",
                             ret);
                        goto out;
                }
        }

do_next:
        if (con->state == CEPH_CON_S_OPEN) {
                if (ceph_con_flag_test_and_clear(con,
                                CEPH_CON_F_KEEPALIVE_PENDING)) {
                        prepare_write_keepalive(con);
                        goto more;
                }
                /* is anything else pending? */
                if ((msg = ceph_con_get_out_msg(con)) != NULL) {
                        prepare_write_message(con, msg);
                        goto more;
                }
                if (con->in_seq > con->in_seq_acked) {
                        prepare_write_ack(con);
                        goto more;
                }
        }

        /* Nothing to do! */
        ceph_con_flag_clear(con, CEPH_CON_F_WRITE_PENDING);
        dout("try_write nothing else to write.\n");
        ret = 0;
out:
        dout("try_write done on %p ret %d\n", con, ret);
        return ret;
}

void ceph_con_v1_revoke(struct ceph_connection *con, struct ceph_msg *msg)
{
        WARN_ON(con->v1.out_skip);
        /* footer */
        if (con->v1.out_msg_done) {
                con->v1.out_skip += con_out_kvec_skip(con);
        } else {
                WARN_ON(!msg->data_length);
                con->v1.out_skip += sizeof_footer(con);
        }
        /* data, middle, front */
        if (msg->data_length)
                con->v1.out_skip += msg->cursor.total_resid;
        if (msg->middle)
                con->v1.out_skip += con_out_kvec_skip(con);
        con->v1.out_skip += con_out_kvec_skip(con);

        dout("%s con %p out_kvec_bytes %d out_skip %d\n", __func__, con,
             con->v1.out_kvec_bytes, con->v1.out_skip);
}

void ceph_con_v1_revoke_incoming(struct ceph_connection *con)
{
        unsigned int front_len = le32_to_cpu(con->v1.in_hdr.front_len);
        unsigned int middle_len = le32_to_cpu(con->v1.in_hdr.middle_len);
        unsigned int data_len = le32_to_cpu(con->v1.in_hdr.data_len);

        /* skip rest of message */
        con->v1.in_base_pos = con->v1.in_base_pos -
                        sizeof(struct ceph_msg_header) -
                        front_len -
                        middle_len -
                        data_len -
                        sizeof(struct ceph_msg_footer);

        con->v1.in_tag = CEPH_MSGR_TAG_READY;
        con->in_seq++;

        dout("%s con %p in_base_pos %d\n", __func__, con, con->v1.in_base_pos);
}

bool ceph_con_v1_opened(struct ceph_connection *con)
{
        return con->v1.connect_seq;
}

void ceph_con_v1_reset_session(struct ceph_connection *con)
{
        con->v1.connect_seq = 0;
        con->v1.peer_global_seq = 0;
}

void ceph_con_v1_reset_protocol(struct ceph_connection *con)
{
        con->v1.out_skip = 0;
}