ceph: factor out libceph from Ceph file system

This factors out protocol and low-level storage parts of ceph into a
separate libceph module living in net/ceph and include/linux/ceph.  This
is mostly a matter of moving files around.  However, a few key pieces
of the interface change as well:

 - ceph_client becomes ceph_fs_client and ceph_client, where the latter
   captures the mon and osd clients, and the fs_client gets the mds client
   and file system specific pieces.
 - Mount option parsing and debugfs setup is correspondingly broken into
   two pieces.
 - The mon client gets a generic handler callback for otherwise unknown
   messages (mds map, in this case).
 - The basic supported/required feature bits can be expanded (and are by
   ceph_fs_client).

No functional change, aside from some subtle error handling cases that got
cleaned up in the refactoring process.

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 2453 insertions, 0 deletions

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
new file mode 100644
index 000000000000..0e8157ee5d43
--- /dev/null
+++ b/net/ceph/messenger.c
@@ -0,0 +1,2453 @@
+#include <linux/ceph/ceph_debug.h>
+
+#include <linux/crc32c.h>
+#include <linux/ctype.h>
+#include <linux/highmem.h>
+#include <linux/inet.h>
+#include <linux/kthread.h>
+#include <linux/net.h>
+#include <linux/slab.h>
+#include <linux/socket.h>
+#include <linux/string.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <net/tcp.h>
+
+#include <linux/ceph/libceph.h>
+#include <linux/ceph/messenger.h>
+#include <linux/ceph/decode.h>
+#include <linux/ceph/pagelist.h>
+
+/*
+ * Ceph uses the messenger to exchange ceph_msg messages with other
+ * hosts in the system.  The messenger provides ordered and reliable
+ * delivery.  We tolerate TCP disconnects by reconnecting (with
+ * exponential backoff) in the case of a fault (disconnection, bad
+ * crc, protocol error).  Acks allow sent messages to be discarded by
+ * the sender.
+ */
+
+/* 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;
+
+#ifdef CONFIG_LOCKDEP
+static struct lock_class_key socket_class;
+#endif
+
+
+static void queue_con(struct ceph_connection *con);
+static void con_work(struct work_struct *);
+static void ceph_fault(struct ceph_connection *con);
+
+/*
+ * nicely render a sockaddr as a string.
+ */
+#define MAX_ADDR_STR 20
+#define MAX_ADDR_STR_LEN 60
+static char addr_str[MAX_ADDR_STR][MAX_ADDR_STR_LEN];
+static DEFINE_SPINLOCK(addr_str_lock);
+static int last_addr_str;
+
+const char *ceph_pr_addr(const struct sockaddr_storage *ss)
+{
+        int i;
+        char *s;
+        struct sockaddr_in *in4 = (void *)ss;
+        struct sockaddr_in6 *in6 = (void *)ss;
+
+        spin_lock(&addr_str_lock);
+        i = last_addr_str++;
+        if (last_addr_str == MAX_ADDR_STR)
+                last_addr_str = 0;
+        spin_unlock(&addr_str_lock);
+        s = addr_str[i];
+
+        switch (ss->ss_family) {
+        case AF_INET:
+                snprintf(s, MAX_ADDR_STR_LEN, "%pI4:%u", &in4->sin_addr,
+                         (unsigned int)ntohs(in4->sin_port));
+                break;
+
+        case AF_INET6:
+                snprintf(s, MAX_ADDR_STR_LEN, "[%pI6c]:%u", &in6->sin6_addr,
+                         (unsigned int)ntohs(in6->sin6_port));
+                break;
+
+        default:
+                sprintf(s, "(unknown sockaddr family %d)", (int)ss->ss_family);
+        }
+
+        return s;
+}
+EXPORT_SYMBOL(ceph_pr_addr);
+
+static void encode_my_addr(struct ceph_messenger *msgr)
+{
+        memcpy(&msgr->my_enc_addr, &msgr->inst.addr, sizeof(msgr->my_enc_addr));
+        ceph_encode_addr(&msgr->my_enc_addr);
+}
+
+/*
+ * work queue for all reading and writing to/from the socket.
+ */
+struct workqueue_struct *ceph_msgr_wq;
+
+int ceph_msgr_init(void)
+{
+        ceph_msgr_wq = create_workqueue("ceph-msgr");
+        if (IS_ERR(ceph_msgr_wq)) {
+                int ret = PTR_ERR(ceph_msgr_wq);
+                pr_err("msgr_init failed to create workqueue: %d\n", ret);
+                ceph_msgr_wq = NULL;
+                return ret;
+        }
+        return 0;
+}
+EXPORT_SYMBOL(ceph_msgr_init);
+
+void ceph_msgr_exit(void)
+{
+        destroy_workqueue(ceph_msgr_wq);
+}
+EXPORT_SYMBOL(ceph_msgr_exit);
+
+void ceph_msgr_flush(void)
+{
+        flush_workqueue(ceph_msgr_wq);
+}
+EXPORT_SYMBOL(ceph_msgr_flush);
+
+
+/*
+ * socket callback functions
+ */
+
+/* data available on socket, or listen socket received a connect */
+static void ceph_data_ready(struct sock *sk, int count_unused)
+{
+        struct ceph_connection *con =
+                (struct ceph_connection *)sk->sk_user_data;
+        if (sk->sk_state != TCP_CLOSE_WAIT) {
+                dout("ceph_data_ready on %p state = %lu, queueing work\n",
+                     con, con->state);
+                queue_con(con);
+        }
+}
+
+/* socket has buffer space for writing */
+static void ceph_write_space(struct sock *sk)
+{
+        struct ceph_connection *con =
+                (struct ceph_connection *)sk->sk_user_data;
+
+        /* only queue to workqueue if there is data we want to write. */
+        if (test_bit(WRITE_PENDING, &con->state)) {
+                dout("ceph_write_space %p queueing write work\n", con);
+                queue_con(con);
+        } else {
+                dout("ceph_write_space %p nothing to write\n", con);
+        }
+
+        /* since we have our own write_space, clear the SOCK_NOSPACE flag */
+        clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+}
+
+/* socket's state has changed */
+static void ceph_state_change(struct sock *sk)
+{
+        struct ceph_connection *con =
+                (struct ceph_connection *)sk->sk_user_data;
+
+        dout("ceph_state_change %p state = %lu sk_state = %u\n",
+             con, con->state, sk->sk_state);
+
+        if (test_bit(CLOSED, &con->state))
+                return;
+
+        switch (sk->sk_state) {
+        case TCP_CLOSE:
+                dout("ceph_state_change TCP_CLOSE\n");
+        case TCP_CLOSE_WAIT:
+                dout("ceph_state_change TCP_CLOSE_WAIT\n");
+                if (test_and_set_bit(SOCK_CLOSED, &con->state) == 0) {
+                        if (test_bit(CONNECTING, &con->state))
+                                con->error_msg = "connection failed";
+                        else
+                                con->error_msg = "socket closed";
+                        queue_con(con);
+                }
+                break;
+        case TCP_ESTABLISHED:
+                dout("ceph_state_change TCP_ESTABLISHED\n");
+                queue_con(con);
+                break;
+        }
+}
+
+/*
+ * set up socket callbacks
+ */
+static void set_sock_callbacks(struct socket *sock,
+                               struct ceph_connection *con)
+{
+        struct sock *sk = sock->sk;
+        sk->sk_user_data = (void *)con;
+        sk->sk_data_ready = ceph_data_ready;
+        sk->sk_write_space = ceph_write_space;
+        sk->sk_state_change = ceph_state_change;
+}
+
+
+/*
+ * socket helpers
+ */
+
+/*
+ * initiate connection to a remote socket.
+ */
+static struct socket *ceph_tcp_connect(struct ceph_connection *con)
+{
+        struct sockaddr_storage *paddr = &con->peer_addr.in_addr;
+        struct socket *sock;
+        int ret;
+
+        BUG_ON(con->sock);
+        ret = sock_create_kern(con->peer_addr.in_addr.ss_family, SOCK_STREAM,
+                               IPPROTO_TCP, &sock);
+        if (ret)
+                return ERR_PTR(ret);
+        con->sock = sock;
+        sock->sk->sk_allocation = GFP_NOFS;
+
+#ifdef CONFIG_LOCKDEP
+        lockdep_set_class(&sock->sk->sk_lock, &socket_class);
+#endif
+
+        set_sock_callbacks(sock, con);
+
+        dout("connect %s\n", ceph_pr_addr(&con->peer_addr.in_addr));
+
+        ret = sock->ops->connect(sock, (struct sockaddr *)paddr, sizeof(*paddr),
+                                 O_NONBLOCK);
+        if (ret == -EINPROGRESS) {
+                dout("connect %s EINPROGRESS sk_state = %u\n",
+                     ceph_pr_addr(&con->peer_addr.in_addr),
+                     sock->sk->sk_state);
+                ret = 0;
+        }
+        if (ret < 0) {
+                pr_err("connect %s error %d\n",
+                       ceph_pr_addr(&con->peer_addr.in_addr), ret);
+                sock_release(sock);
+                con->sock = NULL;
+                con->error_msg = "connect error";
+        }
+
+        if (ret < 0)
+                return ERR_PTR(ret);
+        return sock;
+}
+
+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 };
+
+        return kernel_recvmsg(sock, &msg, &iov, 1, len, msg.msg_flags);
+}
+
+/*
+ * 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, int more)
+{
+        struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL };
+
+        if (more)
+                msg.msg_flags |= MSG_MORE;
+        else
+                msg.msg_flags |= MSG_EOR;  /* superfluous, but what the hell */
+
+        return kernel_sendmsg(sock, &msg, iov, kvlen, len);
+}
+
+
+/*
+ * Shutdown/close the socket for the given connection.
+ */
+static int con_close_socket(struct ceph_connection *con)
+{
+        int rc;
+
+        dout("con_close_socket on %p sock %p\n", con, con->sock);
+        if (!con->sock)
+                return 0;
+        set_bit(SOCK_CLOSED, &con->state);
+        rc = con->sock->ops->shutdown(con->sock, SHUT_RDWR);
+        sock_release(con->sock);
+        con->sock = NULL;
+        clear_bit(SOCK_CLOSED, &con->state);
+        return rc;
+}
+
+/*
+ * Reset a connection.  Discard all incoming and outgoing messages
+ * and clear *_seq state.
+ */
+static void ceph_msg_remove(struct ceph_msg *msg)
+{
+        list_del_init(&msg->list_head);
+        ceph_msg_put(msg);
+}
+static void ceph_msg_remove_list(struct list_head *head)
+{
+        while (!list_empty(head)) {
+                struct ceph_msg *msg = list_first_entry(head, struct ceph_msg,
+                                                        list_head);
+                ceph_msg_remove(msg);
+        }
+}
+
+static void reset_connection(struct ceph_connection *con)
+{
+        /* reset connection, out_queue, msg_ and connect_seq */
+        /* discard existing out_queue and msg_seq */
+        ceph_msg_remove_list(&con->out_queue);
+        ceph_msg_remove_list(&con->out_sent);
+
+        if (con->in_msg) {
+                ceph_msg_put(con->in_msg);
+                con->in_msg = NULL;
+        }
+
+        con->connect_seq = 0;
+        con->out_seq = 0;
+        if (con->out_msg) {
+                ceph_msg_put(con->out_msg);
+                con->out_msg = NULL;
+        }
+        con->out_keepalive_pending = false;
+        con->in_seq = 0;
+        con->in_seq_acked = 0;
+}
+
+/*
+ * mark a peer down.  drop any open connections.
+ */
+void ceph_con_close(struct ceph_connection *con)
+{
+        dout("con_close %p peer %s\n", con,
+             ceph_pr_addr(&con->peer_addr.in_addr));
+        set_bit(CLOSED, &con->state);  /* in case there's queued work */
+        clear_bit(STANDBY, &con->state);  /* avoid connect_seq bump */
+        clear_bit(LOSSYTX, &con->state);  /* so we retry next connect */
+        clear_bit(KEEPALIVE_PENDING, &con->state);
+        clear_bit(WRITE_PENDING, &con->state);
+        mutex_lock(&con->mutex);
+        reset_connection(con);
+        con->peer_global_seq = 0;
+        cancel_delayed_work(&con->work);
+        mutex_unlock(&con->mutex);
+        queue_con(con);
+}
+EXPORT_SYMBOL(ceph_con_close);
+
+/*
+ * Reopen a closed connection, with a new peer address.
+ */
+void ceph_con_open(struct ceph_connection *con, struct ceph_entity_addr *addr)
+{
+        dout("con_open %p %s\n", con, ceph_pr_addr(&addr->in_addr));
+        set_bit(OPENING, &con->state);
+        clear_bit(CLOSED, &con->state);
+        memcpy(&con->peer_addr, addr, sizeof(*addr));
+        con->delay = 0;      /* reset backoff memory */
+        queue_con(con);
+}
+EXPORT_SYMBOL(ceph_con_open);
+
+/*
+ * return true if this connection ever successfully opened
+ */
+bool ceph_con_opened(struct ceph_connection *con)
+{
+        return con->connect_seq > 0;
+}
+
+/*
+ * generic get/put
+ */
+struct ceph_connection *ceph_con_get(struct ceph_connection *con)
+{
+        dout("con_get %p nref = %d -> %d\n", con,
+             atomic_read(&con->nref), atomic_read(&con->nref) + 1);
+        if (atomic_inc_not_zero(&con->nref))
+                return con;
+        return NULL;
+}
+
+void ceph_con_put(struct ceph_connection *con)
+{
+        dout("con_put %p nref = %d -> %d\n", con,
+             atomic_read(&con->nref), atomic_read(&con->nref) - 1);
+        BUG_ON(atomic_read(&con->nref) == 0);
+        if (atomic_dec_and_test(&con->nref)) {
+                BUG_ON(con->sock);
+                kfree(con);
+        }
+}
+
+/*
+ * initialize a new connection.
+ */
+void ceph_con_init(struct ceph_messenger *msgr, struct ceph_connection *con)
+{
+        dout("con_init %p\n", con);
+        memset(con, 0, sizeof(*con));
+        atomic_set(&con->nref, 1);
+        con->msgr = msgr;
+        mutex_init(&con->mutex);
+        INIT_LIST_HEAD(&con->out_queue);
+        INIT_LIST_HEAD(&con->out_sent);
+        INIT_DELAYED_WORK(&con->work, con_work);
+}
+EXPORT_SYMBOL(ceph_con_init);
+
+
+/*
+ * We maintain a global counter to order connection attempts.  Get
+ * a unique seq greater than @gt.
+ */
+static u32 get_global_seq(struct ceph_messenger *msgr, u32 gt)
+{
+        u32 ret;
+
+        spin_lock(&msgr->global_seq_lock);
+        if (msgr->global_seq < gt)
+                msgr->global_seq = gt;
+        ret = ++msgr->global_seq;
+        spin_unlock(&msgr->global_seq_lock);
+        return ret;
+}
+
+
+/*
+ * 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, int v)
+{
+        struct ceph_msg *m = con->out_msg;
+
+        dout("prepare_write_message_footer %p\n", con);
+        con->out_kvec_is_msg = true;
+        con->out_kvec[v].iov_base = &m->footer;
+        con->out_kvec[v].iov_len = sizeof(m->footer);
+        con->out_kvec_bytes += sizeof(m->footer);
+        con->out_kvec_left++;
+        con->out_more = m->more_to_follow;
+        con->out_msg_done = true;
+}
+
+/*
+ * Prepare headers for the next outgoing message.
+ */
+static void prepare_write_message(struct ceph_connection *con)
+{
+        struct ceph_msg *m;
+        int v = 0;
+
+        con->out_kvec_bytes = 0;
+        con->out_kvec_is_msg = true;
+        con->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[v].iov_base = &tag_ack;
+                con->out_kvec[v++].iov_len = 1;
+                con->out_temp_ack = cpu_to_le64(con->in_seq_acked);
+                con->out_kvec[v].iov_base = &con->out_temp_ack;
+                con->out_kvec[v++].iov_len = sizeof(con->out_temp_ack);
+                con->out_kvec_bytes = 1 + sizeof(con->out_temp_ack);
+        }
+
+        m = list_first_entry(&con->out_queue,
+                       struct ceph_msg, list_head);
+        con->out_msg = m;
+        if (test_bit(LOSSYTX, &con->state)) {
+                list_del_init(&m->list_head);
+        } else {
+                /* put message on sent list */
+                ceph_msg_get(m);
+                list_move_tail(&m->list_head, &con->out_sent);
+        }
+
+        /*
+         * only assign outgoing seq # if we haven't sent this message
+         * yet.  if it is requeued, resend with it's original seq.
+         */
+        if (m->needs_out_seq) {
+                m->hdr.seq = cpu_to_le64(++con->out_seq);
+                m->needs_out_seq = false;
+        }
+
+        dout("prepare_write_message %p seq %lld type %d len %d+%d+%d %d pgs\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),
+             le32_to_cpu(m->hdr.data_len),
+             m->nr_pages);
+        BUG_ON(le32_to_cpu(m->hdr.front_len) != m->front.iov_len);
+
+        /* tag + hdr + front + middle */
+        con->out_kvec[v].iov_base = &tag_msg;
+        con->out_kvec[v++].iov_len = 1;
+        con->out_kvec[v].iov_base = &m->hdr;
+        con->out_kvec[v++].iov_len = sizeof(m->hdr);
+        con->out_kvec[v++] = m->front;
+        if (m->middle)
+                con->out_kvec[v++] = m->middle->vec;
+        con->out_kvec_left = v;
+        con->out_kvec_bytes += 1 + sizeof(m->hdr) + m->front.iov_len +
+                (m->middle ? m->middle->vec.iov_len : 0);
+        con->out_kvec_cur = con->out_kvec;
+
+        /* fill in crc (except data pages), footer */
+        con->out_msg->hdr.crc =
+                cpu_to_le32(crc32c(0, (void *)&m->hdr,
+                                      sizeof(m->hdr) - sizeof(m->hdr.crc)));
+        con->out_msg->footer.flags = CEPH_MSG_FOOTER_COMPLETE;
+        con->out_msg->footer.front_crc =
+                cpu_to_le32(crc32c(0, m->front.iov_base, m->front.iov_len));
+        if (m->middle)
+                con->out_msg->footer.middle_crc =
+                        cpu_to_le32(crc32c(0, m->middle->vec.iov_base,
+                                           m->middle->vec.iov_len));
+        else
+                con->out_msg->footer.middle_crc = 0;
+        con->out_msg->footer.data_crc = 0;
+        dout("prepare_write_message front_crc %u data_crc %u\n",
+             le32_to_cpu(con->out_msg->footer.front_crc),
+             le32_to_cpu(con->out_msg->footer.middle_crc));
+
+        /* is there a data payload? */
+        if (le32_to_cpu(m->hdr.data_len) > 0) {
+                /* initialize page iterator */
+                con->out_msg_pos.page = 0;
+                if (m->pages)
+                        con->out_msg_pos.page_pos =
+                                le16_to_cpu(m->hdr.data_off) & ~PAGE_MASK;
+                else
+                        con->out_msg_pos.page_pos = 0;
+                con->out_msg_pos.data_pos = 0;
+                con->out_msg_pos.did_page_crc = 0;
+                con->out_more = 1;  /* data + footer will follow */
+        } else {
+                /* no, queue up footer too and be done */
+                prepare_write_message_footer(con, v);
+        }
+
+        set_bit(WRITE_PENDING, &con->state);
+}
+
+/*
+ * 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[0].iov_base = &tag_ack;
+        con->out_kvec[0].iov_len = 1;
+        con->out_temp_ack = cpu_to_le64(con->in_seq_acked);
+        con->out_kvec[1].iov_base = &con->out_temp_ack;
+        con->out_kvec[1].iov_len = sizeof(con->out_temp_ack);
+        con->out_kvec_left = 2;
+        con->out_kvec_bytes = 1 + sizeof(con->out_temp_ack);
+        con->out_kvec_cur = con->out_kvec;
+        con->out_more = 1;  /* more will follow.. eventually.. */
+        set_bit(WRITE_PENDING, &con->state);
+}
+
+/*
+ * Prepare to write keepalive byte.
+ */
+static void prepare_write_keepalive(struct ceph_connection *con)
+{
+        dout("prepare_write_keepalive %p\n", con);
+        con->out_kvec[0].iov_base = &tag_keepalive;
+        con->out_kvec[0].iov_len = 1;
+        con->out_kvec_left = 1;
+        con->out_kvec_bytes = 1;
+        con->out_kvec_cur = con->out_kvec;
+        set_bit(WRITE_PENDING, &con->state);
+}
+
+/*
+ * Connection negotiation.
+ */
+
+static void prepare_connect_authorizer(struct ceph_connection *con)
+{
+        void *auth_buf;
+        int auth_len = 0;
+        int auth_protocol = 0;
+
+        mutex_unlock(&con->mutex);
+        if (con->ops->get_authorizer)
+                con->ops->get_authorizer(con, &auth_buf, &auth_len,
+                                         &auth_protocol, &con->auth_reply_buf,
+                                         &con->auth_reply_buf_len,
+                                         con->auth_retry);
+        mutex_lock(&con->mutex);
+
+        con->out_connect.authorizer_protocol = cpu_to_le32(auth_protocol);
+        con->out_connect.authorizer_len = cpu_to_le32(auth_len);
+
+        con->out_kvec[con->out_kvec_left].iov_base = auth_buf;
+        con->out_kvec[con->out_kvec_left].iov_len = auth_len;
+        con->out_kvec_left++;
+        con->out_kvec_bytes += auth_len;
+}
+
+/*
+ * We connected to a peer and are saying hello.
+ */
+static void prepare_write_banner(struct ceph_messenger *msgr,
+                                 struct ceph_connection *con)
+{
+        int len = strlen(CEPH_BANNER);
+
+        con->out_kvec[0].iov_base = CEPH_BANNER;
+        con->out_kvec[0].iov_len = len;
+        con->out_kvec[1].iov_base = &msgr->my_enc_addr;
+        con->out_kvec[1].iov_len = sizeof(msgr->my_enc_addr);
+        con->out_kvec_left = 2;
+        con->out_kvec_bytes = len + sizeof(msgr->my_enc_addr);
+        con->out_kvec_cur = con->out_kvec;
+        con->out_more = 0;
+        set_bit(WRITE_PENDING, &con->state);
+}
+
+static void prepare_write_connect(struct ceph_messenger *msgr,
+                                  struct ceph_connection *con,
+                                  int after_banner)
+{
+        unsigned global_seq = get_global_seq(con->msgr, 0);
+        int proto;
+
+        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->connect_seq, global_seq, proto);
+
+        con->out_connect.features = cpu_to_le64(msgr->supported_features);
+        con->out_connect.host_type = cpu_to_le32(CEPH_ENTITY_TYPE_CLIENT);
+        con->out_connect.connect_seq = cpu_to_le32(con->connect_seq);
+        con->out_connect.global_seq = cpu_to_le32(global_seq);
+        con->out_connect.protocol_version = cpu_to_le32(proto);
+        con->out_connect.flags = 0;
+
+        if (!after_banner) {
+                con->out_kvec_left = 0;
+                con->out_kvec_bytes = 0;
+        }
+        con->out_kvec[con->out_kvec_left].iov_base = &con->out_connect;
+        con->out_kvec[con->out_kvec_left].iov_len = sizeof(con->out_connect);
+        con->out_kvec_left++;
+        con->out_kvec_bytes += sizeof(con->out_connect);
+        con->out_kvec_cur = con->out_kvec;
+        con->out_more = 0;
+        set_bit(WRITE_PENDING, &con->state);
+
+        prepare_connect_authorizer(con);
+}
+
+
+/*
+ * 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->out_kvec_bytes);
+        while (con->out_kvec_bytes > 0) {
+                ret = ceph_tcp_sendmsg(con->sock, con->out_kvec_cur,
+                                       con->out_kvec_left, con->out_kvec_bytes,
+                                       con->out_more);
+                if (ret <= 0)
+                        goto out;
+                con->out_kvec_bytes -= ret;
+                if (con->out_kvec_bytes == 0)
+                        break;            /* done */
+                while (ret > 0) {
+                        if (ret >= con->out_kvec_cur->iov_len) {
+                                ret -= con->out_kvec_cur->iov_len;
+                                con->out_kvec_cur++;
+                                con->out_kvec_left--;
+                        } else {
+                                con->out_kvec_cur->iov_len -= ret;
+                                con->out_kvec_cur->iov_base += ret;
+                                ret = 0;
+                                break;
+                        }
+                }
+        }
+        con->out_kvec_left = 0;
+        con->out_kvec_is_msg = false;
+        ret = 1;
+out:
+        dout("write_partial_kvec %p %d left in %d kvecs ret = %d\n", con,
+             con->out_kvec_bytes, con->out_kvec_left, ret);
+        return ret;  /* done! */
+}
+
+#ifdef CONFIG_BLOCK
+static void init_bio_iter(struct bio *bio, struct bio **iter, int *seg)
+{
+        if (!bio) {
+                *iter = NULL;
+                *seg = 0;
+                return;
+        }
+        *iter = bio;
+        *seg = bio->bi_idx;
+}
+
+static void iter_bio_next(struct bio **bio_iter, int *seg)
+{
+        if (*bio_iter == NULL)
+                return;
+
+        BUG_ON(*seg >= (*bio_iter)->bi_vcnt);
+
+        (*seg)++;
+        if (*seg == (*bio_iter)->bi_vcnt)
+                init_bio_iter((*bio_iter)->bi_next, bio_iter, seg);
+}
+#endif
+
+/*
+ * 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_msg_pages(struct ceph_connection *con)
+{
+        struct ceph_msg *msg = con->out_msg;
+        unsigned data_len = le32_to_cpu(msg->hdr.data_len);
+        size_t len;
+        int crc = con->msgr->nocrc;
+        int ret;
+        int total_max_write;
+        int in_trail = 0;
+        size_t trail_len = (msg->trail ? msg->trail->length : 0);
+
+        dout("write_partial_msg_pages %p msg %p page %d/%d offset %d\n",
+             con, con->out_msg, con->out_msg_pos.page, con->out_msg->nr_pages,
+             con->out_msg_pos.page_pos);
+
+#ifdef CONFIG_BLOCK
+        if (msg->bio && !msg->bio_iter)
+                init_bio_iter(msg->bio, &msg->bio_iter, &msg->bio_seg);
+#endif
+
+        while (data_len > con->out_msg_pos.data_pos) {
+                struct page *page = NULL;
+                void *kaddr = NULL;
+                int max_write = PAGE_SIZE;
+                int page_shift = 0;
+
+                total_max_write = data_len - trail_len -
+                        con->out_msg_pos.data_pos;
+
+                /*
+                 * if we are calculating the data crc (the default), we need
+                 * to map the page.  if our pages[] has been revoked, use the
+                 * zero page.
+                 */
+
+                /* have we reached the trail part of the data? */
+                if (con->out_msg_pos.data_pos >= data_len - trail_len) {
+                        in_trail = 1;
+
+                        total_max_write = data_len - con->out_msg_pos.data_pos;
+
+                        page = list_first_entry(&msg->trail->head,
+                                                struct page, lru);
+                        if (crc)
+                                kaddr = kmap(page);
+                        max_write = PAGE_SIZE;
+                } else if (msg->pages) {
+                        page = msg->pages[con->out_msg_pos.page];
+                        if (crc)
+                                kaddr = kmap(page);
+                } else if (msg->pagelist) {
+                        page = list_first_entry(&msg->pagelist->head,
+                                                struct page, lru);
+                        if (crc)
+                                kaddr = kmap(page);
+#ifdef CONFIG_BLOCK
+                } else if (msg->bio) {
+                        struct bio_vec *bv;
+
+                        bv = bio_iovec_idx(msg->bio_iter, msg->bio_seg);
+                        page = bv->bv_page;
+                        page_shift = bv->bv_offset;
+                        if (crc)
+                                kaddr = kmap(page) + page_shift;
+                        max_write = bv->bv_len;
+#endif
+                } else {
+                        page = con->msgr->zero_page;
+                        if (crc)
+                                kaddr = page_address(con->msgr->zero_page);
+                }
+                len = min_t(int, max_write - con->out_msg_pos.page_pos,
+                            total_max_write);
+
+                if (crc && !con->out_msg_pos.did_page_crc) {
+                        void *base = kaddr + con->out_msg_pos.page_pos;
+                        u32 tmpcrc = le32_to_cpu(con->out_msg->footer.data_crc);
+
+                        BUG_ON(kaddr == NULL);
+                        con->out_msg->footer.data_crc =
+                                cpu_to_le32(crc32c(tmpcrc, base, len));
+                        con->out_msg_pos.did_page_crc = 1;
+                }
+                ret = kernel_sendpage(con->sock, page,
+                                      con->out_msg_pos.page_pos + page_shift,
+                                      len,
+                                      MSG_DONTWAIT | MSG_NOSIGNAL |
+                                      MSG_MORE);
+
+                if (crc &&
+                    (msg->pages || msg->pagelist || msg->bio || in_trail))
+                        kunmap(page);
+
+                if (ret <= 0)
+                        goto out;
+
+                con->out_msg_pos.data_pos += ret;
+                con->out_msg_pos.page_pos += ret;
+                if (ret == len) {
+                        con->out_msg_pos.page_pos = 0;
+                        con->out_msg_pos.page++;
+                        con->out_msg_pos.did_page_crc = 0;
+                        if (in_trail)
+                                list_move_tail(&page->lru,
+                                               &msg->trail->head);
+                        else if (msg->pagelist)
+                                list_move_tail(&page->lru,
+                                               &msg->pagelist->head);
+#ifdef CONFIG_BLOCK
+                        else if (msg->bio)
+                                iter_bio_next(&msg->bio_iter, &msg->bio_seg);
+#endif
+                }
+        }
+
+        dout("write_partial_msg_pages %p msg %p done\n", con, msg);
+
+        /* prepare and queue up footer, too */
+        if (!crc)
+                con->out_msg->footer.flags |= CEPH_MSG_FOOTER_NOCRC;
+        con->out_kvec_bytes = 0;
+        con->out_kvec_left = 0;
+        con->out_kvec_cur = con->out_kvec;
+        prepare_write_message_footer(con, 0);
+        ret = 1;
+out:
+        return ret;
+}
+
+/*
+ * write some zeros
+ */
+static int write_partial_skip(struct ceph_connection *con)
+{
+        int ret;
+
+        while (con->out_skip > 0) {
+                struct kvec iov = {
+                        .iov_base = page_address(con->msgr->zero_page),
+                        .iov_len = min(con->out_skip, (int)PAGE_CACHE_SIZE)
+                };
+
+                ret = ceph_tcp_sendmsg(con->sock, &iov, 1, iov.iov_len, 1);
+                if (ret <= 0)
+                        goto out;
+                con->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->in_base_pos = 0;
+}
+
+static void prepare_read_connect(struct ceph_connection *con)
+{
+        dout("prepare_read_connect %p\n", con);
+        con->in_base_pos = 0;
+}
+
+static void prepare_read_ack(struct ceph_connection *con)
+{
+        dout("prepare_read_ack %p\n", con);
+        con->in_base_pos = 0;
+}
+
+static void prepare_read_tag(struct ceph_connection *con)
+{
+        dout("prepare_read_tag %p\n", con);
+        con->in_base_pos = 0;
+        con->in_tag = CEPH_MSGR_TAG_READY;
+}
+
+/*
+ * 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->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 *to, int size, void *object)
+{
+        *to += size;
+        while (con->in_base_pos < *to) {
+                int left = *to - con->in_base_pos;
+                int have = size - left;
+                int ret = ceph_tcp_recvmsg(con->sock, object + have, left);
+                if (ret <= 0)
+                        return ret;
+                con->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 ret, to = 0;
+
+        dout("read_partial_banner %p at %d\n", con, con->in_base_pos);
+
+        /* peer's banner */
+        ret = read_partial(con, &to, strlen(CEPH_BANNER), con->in_banner);
+        if (ret <= 0)
+                goto out;
+        ret = read_partial(con, &to, sizeof(con->actual_peer_addr),
+                           &con->actual_peer_addr);
+        if (ret <= 0)
+                goto out;
+        ret = read_partial(con, &to, sizeof(con->peer_addr_for_me),
+                           &con->peer_addr_for_me);
+        if (ret <= 0)
+                goto out;
+out:
+        return ret;
+}
+
+static int read_partial_connect(struct ceph_connection *con)
+{
+        int ret, to = 0;
+
+        dout("read_partial_connect %p at %d\n", con, con->in_base_pos);
+
+        ret = read_partial(con, &to, sizeof(con->in_reply), &con->in_reply);
+        if (ret <= 0)
+                goto out;
+        ret = read_partial(con, &to, le32_to_cpu(con->in_reply.authorizer_len),
+                           con->auth_reply_buf);
+        if (ret <= 0)
+                goto out;
+
+        dout("read_partial_connect %p tag %d, con_seq = %u, g_seq = %u\n",
+             con, (int)con->in_reply.tag,
+             le32_to_cpu(con->in_reply.connect_seq),
+             le32_to_cpu(con->in_reply.global_seq));
+out:
+        return ret;
+
+}
+
+/*
+ * Verify the hello banner looks okay.
+ */
+static int verify_hello(struct ceph_connection *con)
+{
+        if (memcmp(con->in_banner, CEPH_BANNER, strlen(CEPH_BANNER))) {
+                pr_err("connect to %s got bad banner\n",
+                       ceph_pr_addr(&con->peer_addr.in_addr));
+                con->error_msg = "protocol error, bad banner";
+                return -1;
+        }
+        return 0;
+}
+
+static bool addr_is_blank(struct sockaddr_storage *ss)
+{
+        switch (ss->ss_family) {
+        case AF_INET:
+                return ((struct sockaddr_in *)ss)->sin_addr.s_addr == 0;
+        case AF_INET6:
+                return
+                     ((struct sockaddr_in6 *)ss)->sin6_addr.s6_addr32[0] == 0 &&
+                     ((struct sockaddr_in6 *)ss)->sin6_addr.s6_addr32[1] == 0 &&
+                     ((struct sockaddr_in6 *)ss)->sin6_addr.s6_addr32[2] == 0 &&
+                     ((struct sockaddr_in6 *)ss)->sin6_addr.s6_addr32[3] == 0;
+        }
+        return false;
+}
+
+static int addr_port(struct sockaddr_storage *ss)
+{
+        switch (ss->ss_family) {
+        case AF_INET:
+                return ntohs(((struct sockaddr_in *)ss)->sin_port);
+        case AF_INET6:
+                return ntohs(((struct sockaddr_in6 *)ss)->sin6_port);
+        }
+        return 0;
+}
+
+static void addr_set_port(struct sockaddr_storage *ss, int p)
+{
+        switch (ss->ss_family) {
+        case AF_INET:
+                ((struct sockaddr_in *)ss)->sin_port = htons(p);
+        case AF_INET6:
+                ((struct sockaddr_in6 *)ss)->sin6_port = htons(p);
+        }
+}
+
+/*
+ * Parse an ip[:port] list into an addr array.  Use the default
+ * monitor port if a port isn't specified.
+ */
+int ceph_parse_ips(const char *c, const char *end,
+                   struct ceph_entity_addr *addr,
+                   int max_count, int *count)
+{
+        int i;
+        const char *p = c;
+
+        dout("parse_ips on '%.*s'\n", (int)(end-c), c);
+        for (i = 0; i < max_count; i++) {
+                const char *ipend;
+                struct sockaddr_storage *ss = &addr[i].in_addr;
+                struct sockaddr_in *in4 = (void *)ss;
+                struct sockaddr_in6 *in6 = (void *)ss;
+                int port;
+                char delim = ',';
+
+                if (*p == '[') {
+                        delim = ']';
+                        p++;
+                }
+
+                memset(ss, 0, sizeof(*ss));
+                if (in4_pton(p, end - p, (u8 *)&in4->sin_addr.s_addr,
+                             delim, &ipend))
+                        ss->ss_family = AF_INET;
+                else if (in6_pton(p, end - p, (u8 *)&in6->sin6_addr.s6_addr,
+                                  delim, &ipend))
+                        ss->ss_family = AF_INET6;
+                else
+                        goto bad;
+                p = ipend;
+
+                if (delim == ']') {
+                        if (*p != ']') {
+                                dout("missing matching ']'\n");
+                                goto bad;
+                        }
+                        p++;
+                }
+
+                /* port? */
+                if (p < end && *p == ':') {
+                        port = 0;
+                        p++;
+                        while (p < end && *p >= '0' && *p <= '9') {
+                                port = (port * 10) + (*p - '0');
+                                p++;
+                        }
+                        if (port > 65535 || port == 0)
+                                goto bad;
+                } else {
+                        port = CEPH_MON_PORT;
+                }
+
+                addr_set_port(ss, port);
+
+                dout("parse_ips got %s\n", ceph_pr_addr(ss));
+
+                if (p == end)
+                        break;
+                if (*p != ',')
+                        goto bad;
+                p++;
+        }
+
+        if (p != end)
+                goto bad;
+
+        if (count)
+                *count = i + 1;
+        return 0;
+
+bad:
+        pr_err("parse_ips bad ip '%.*s'\n", (int)(end - c), c);
+        return -EINVAL;
+}
+EXPORT_SYMBOL(ceph_parse_ips);
+
+static int process_banner(struct ceph_connection *con)
+{
+        dout("process_banner on %p\n", con);
+
+        if (verify_hello(con) < 0)
+                return -1;
+
+        ceph_decode_addr(&con->actual_peer_addr);
+        ceph_decode_addr(&con->peer_addr_for_me);
+
+        /*
+         * 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->actual_peer_addr,
+                   sizeof(con->peer_addr)) != 0 &&
+            !(addr_is_blank(&con->actual_peer_addr.in_addr) &&
+              con->actual_peer_addr.nonce == con->peer_addr.nonce)) {
+                pr_warning("wrong peer, want %s/%d, got %s/%d\n",
+                           ceph_pr_addr(&con->peer_addr.in_addr),
+                           (int)le32_to_cpu(con->peer_addr.nonce),
+                           ceph_pr_addr(&con->actual_peer_addr.in_addr),
+                           (int)le32_to_cpu(con->actual_peer_addr.nonce));
+                con->error_msg = "wrong peer at address";
+                return -1;
+        }
+
+        /*
+         * did we learn our address?
+         */
+        if (addr_is_blank(&con->msgr->inst.addr.in_addr)) {
+                int port = addr_port(&con->msgr->inst.addr.in_addr);
+
+                memcpy(&con->msgr->inst.addr.in_addr,
+                       &con->peer_addr_for_me.in_addr,
+                       sizeof(con->peer_addr_for_me.in_addr));
+                addr_set_port(&con->msgr->inst.addr.in_addr, port);
+                encode_my_addr(con->msgr);
+                dout("process_banner learned my addr is %s\n",
+                     ceph_pr_addr(&con->msgr->inst.addr.in_addr));
+        }
+
+        set_bit(NEGOTIATING, &con->state);
+        prepare_read_connect(con);
+        return 0;
+}
+
+static void fail_protocol(struct ceph_connection *con)
+{
+        reset_connection(con);
+        set_bit(CLOSED, &con->state);  /* in case there's queued work */
+
+        mutex_unlock(&con->mutex);
+        if (con->ops->bad_proto)
+                con->ops->bad_proto(con);
+        mutex_lock(&con->mutex);
+}
+
+static int process_connect(struct ceph_connection *con)
+{
+        u64 sup_feat = con->msgr->supported_features;
+        u64 req_feat = con->msgr->required_features;
+        u64 server_feat = le64_to_cpu(con->in_reply.features);
+
+        dout("process_connect on %p tag %d\n", con, (int)con->in_tag);
+
+        switch (con->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.in_addr),
+                       sup_feat, server_feat, server_feat & ~sup_feat);
+                con->error_msg = "missing required protocol features";
+                fail_protocol(con);
+                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.in_addr),
+                       le32_to_cpu(con->out_connect.protocol_version),
+                       le32_to_cpu(con->in_reply.protocol_version));
+                con->error_msg = "protocol version mismatch";
+                fail_protocol(con);
+                return -1;
+
+        case CEPH_MSGR_TAG_BADAUTHORIZER:
+                con->auth_retry++;
+                dout("process_connect %p got BADAUTHORIZER attempt %d\n", con,
+                     con->auth_retry);
+                if (con->auth_retry == 2) {
+                        con->error_msg = "connect authorization failure";
+                        reset_connection(con);
+                        set_bit(CLOSED, &con->state);
+                        return -1;
+                }
+                con->auth_retry = 1;
+                prepare_write_connect(con->msgr, con, 0);
+                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->in_connect.connect_seq));
+                pr_err("%s%lld %s connection reset\n",
+                       ENTITY_NAME(con->peer_name),
+                       ceph_pr_addr(&con->peer_addr.in_addr));
+                reset_connection(con);
+                prepare_write_connect(con->msgr, con, 0);
+                prepare_read_connect(con);
+
+                /* Tell ceph about it. */
+                mutex_unlock(&con->mutex);
+                pr_info("reset on %s%lld\n", ENTITY_NAME(con->peer_name));
+                if (con->ops->peer_reset)
+                        con->ops->peer_reset(con);
+                mutex_lock(&con->mutex);
+                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 my seq = %u, peer_seq = %u\n",
+                     le32_to_cpu(con->out_connect.connect_seq),
+                     le32_to_cpu(con->in_connect.connect_seq));
+                con->connect_seq = le32_to_cpu(con->in_connect.connect_seq);
+                prepare_write_connect(con->msgr, con, 0);
+                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->peer_global_seq,
+                     le32_to_cpu(con->in_connect.global_seq));
+                get_global_seq(con->msgr,
+                               le32_to_cpu(con->in_connect.global_seq));
+                prepare_write_connect(con->msgr, con, 0);
+                prepare_read_connect(con);
+                break;
+
+        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.in_addr),
+                               req_feat, server_feat, req_feat & ~server_feat);
+                        con->error_msg = "missing required protocol features";
+                        fail_protocol(con);
+                        return -1;
+                }
+                clear_bit(CONNECTING, &con->state);
+                con->peer_global_seq = le32_to_cpu(con->in_reply.global_seq);
+                con->connect_seq++;
+                con->peer_features = server_feat;
+                dout("process_connect got READY gseq %d cseq %d (%d)\n",
+                     con->peer_global_seq,
+                     le32_to_cpu(con->in_reply.connect_seq),
+                     con->connect_seq);
+                WARN_ON(con->connect_seq !=
+                        le32_to_cpu(con->in_reply.connect_seq));
+
+                if (con->in_reply.flags & CEPH_MSG_CONNECT_LOSSY)
+                        set_bit(LOSSYTX, &con->state);
+
+                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.
+                 */
+                pr_err("process_connect peer connecting WAIT\n");
+
+        default:
+                pr_err("connect protocol error, will retry\n");
+                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 to = 0;
+
+        return read_partial(con, &to, sizeof(con->in_temp_ack),
+                            &con->in_temp_ack);
+}
+
+
+/*
+ * We can finally discard anything that's been acked.
+ */
+static void process_ack(struct ceph_connection *con)
+{
+        struct ceph_msg *m;
+        u64 ack = le64_to_cpu(con->in_temp_ack);
+        u64 seq;
+
+        while (!list_empty(&con->out_sent)) {
+                m = list_first_entry(&con->out_sent, struct ceph_msg,
+                                     list_head);
+                seq = le64_to_cpu(m->hdr.seq);
+                if (seq > ack)
+                        break;
+                dout("got ack for seq %llu type %d at %p\n", seq,
+                     le16_to_cpu(m->hdr.type), m);
+                ceph_msg_remove(m);
+        }
+        prepare_read_tag(con);
+}
+
+
+
+
+static int read_partial_message_section(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(0, section->iov_base,
+                                      section->iov_len);
+        }
+
+        return 1;
+}
+
+static struct ceph_msg *ceph_alloc_msg(struct ceph_connection *con,
+                                struct ceph_msg_header *hdr,
+                                int *skip);
+
+
+static int read_partial_message_pages(struct ceph_connection *con,
+                                      struct page **pages,
+                                      unsigned data_len, int datacrc)
+{
+        void *p;
+        int ret;
+        int left;
+
+        left = min((int)(data_len - con->in_msg_pos.data_pos),
+                   (int)(PAGE_SIZE - con->in_msg_pos.page_pos));
+        /* (page) data */
+        BUG_ON(pages == NULL);
+        p = kmap(pages[con->in_msg_pos.page]);
+        ret = ceph_tcp_recvmsg(con->sock, p + con->in_msg_pos.page_pos,
+                               left);
+        if (ret > 0 && datacrc)
+                con->in_data_crc =
+                        crc32c(con->in_data_crc,
+                                  p + con->in_msg_pos.page_pos, ret);
+        kunmap(pages[con->in_msg_pos.page]);
+        if (ret <= 0)
+                return ret;
+        con->in_msg_pos.data_pos += ret;
+        con->in_msg_pos.page_pos += ret;
+        if (con->in_msg_pos.page_pos == PAGE_SIZE) {
+                con->in_msg_pos.page_pos = 0;
+                con->in_msg_pos.page++;
+        }
+
+        return ret;
+}
+
+#ifdef CONFIG_BLOCK
+static int read_partial_message_bio(struct ceph_connection *con,
+                                    struct bio **bio_iter, int *bio_seg,
+                                    unsigned data_len, int datacrc)
+{
+        struct bio_vec *bv = bio_iovec_idx(*bio_iter, *bio_seg);
+        void *p;
+        int ret, left;
+
+        if (IS_ERR(bv))
+                return PTR_ERR(bv);
+
+        left = min((int)(data_len - con->in_msg_pos.data_pos),
+                   (int)(bv->bv_len - con->in_msg_pos.page_pos));
+
+        p = kmap(bv->bv_page) + bv->bv_offset;
+
+        ret = ceph_tcp_recvmsg(con->sock, p + con->in_msg_pos.page_pos,
+                               left);
+        if (ret > 0 && datacrc)
+                con->in_data_crc =
+                        crc32c(con->in_data_crc,
+                                  p + con->in_msg_pos.page_pos, ret);
+        kunmap(bv->bv_page);
+        if (ret <= 0)
+                return ret;
+        con->in_msg_pos.data_pos += ret;
+        con->in_msg_pos.page_pos += ret;
+        if (con->in_msg_pos.page_pos == bv->bv_len) {
+                con->in_msg_pos.page_pos = 0;
+                iter_bio_next(bio_iter, bio_seg);
+        }
+
+        return ret;
+}
+#endif
+
+/*
+ * read (part of) a message.
+ */
+static int read_partial_message(struct ceph_connection *con)
+{
+        struct ceph_msg *m = con->in_msg;
+        int ret;
+        int to, left;
+        unsigned front_len, middle_len, data_len, data_off;
+        int datacrc = con->msgr->nocrc;
+        int skip;
+        u64 seq;
+
+        dout("read_partial_message con %p msg %p\n", con, m);
+
+        /* header */
+        while (con->in_base_pos < sizeof(con->in_hdr)) {
+                left = sizeof(con->in_hdr) - con->in_base_pos;
+                ret = ceph_tcp_recvmsg(con->sock,
+                                       (char *)&con->in_hdr + con->in_base_pos,
+                                       left);
+                if (ret <= 0)
+                        return ret;
+                con->in_base_pos += ret;
+                if (con->in_base_pos == sizeof(con->in_hdr)) {
+                        u32 crc = crc32c(0, (void *)&con->in_hdr,
+                                 sizeof(con->in_hdr) - sizeof(con->in_hdr.crc));
+                        if (crc != le32_to_cpu(con->in_hdr.crc)) {
+                                pr_err("read_partial_message bad hdr "
+                                       " crc %u != expected %u\n",
+                                       crc, con->in_hdr.crc);
+                                return -EBADMSG;
+                        }
+                }
+        }
+        front_len = le32_to_cpu(con->in_hdr.front_len);
+        if (front_len > CEPH_MSG_MAX_FRONT_LEN)
+                return -EIO;
+        middle_len = le32_to_cpu(con->in_hdr.middle_len);
+        if (middle_len > CEPH_MSG_MAX_DATA_LEN)
+                return -EIO;
+        data_len = le32_to_cpu(con->in_hdr.data_len);
+        if (data_len > CEPH_MSG_MAX_DATA_LEN)
+                return -EIO;
+        data_off = le16_to_cpu(con->in_hdr.data_off);
+
+        /* verify seq# */
+        seq = le64_to_cpu(con->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.in_addr),
+                        seq, con->in_seq + 1);
+                con->in_base_pos = -front_len - middle_len - data_len -
+                        sizeof(m->footer);
+                con->in_tag = CEPH_MSGR_TAG_READY;
+                con->in_seq++;
+                return 0;
+        } 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 -EBADMSG;
+        }
+
+        /* allocate message? */
+        if (!con->in_msg) {
+                dout("got hdr type %d front %d data %d\n", con->in_hdr.type,
+                     con->in_hdr.front_len, con->in_hdr.data_len);
+                skip = 0;
+                con->in_msg = ceph_alloc_msg(con, &con->in_hdr, &skip);
+                if (skip) {
+                        /* skip this message */
+                        dout("alloc_msg said skip message\n");
+                        BUG_ON(con->in_msg);
+                        con->in_base_pos = -front_len - middle_len - data_len -
+                                sizeof(m->footer);
+                        con->in_tag = CEPH_MSGR_TAG_READY;
+                        con->in_seq++;
+                        return 0;
+                }
+                if (!con->in_msg) {
+                        con->error_msg =
+                                "error allocating memory for incoming message";
+                        return -ENOMEM;
+                }
+                m = con->in_msg;
+                m->front.iov_len = 0;    /* haven't read it yet */
+                if (m->middle)
+                        m->middle->vec.iov_len = 0;
+
+                con->in_msg_pos.page = 0;
+                if (m->pages)
+                        con->in_msg_pos.page_pos = data_off & ~PAGE_MASK;
+                else
+                        con->in_msg_pos.page_pos = 0;
+                con->in_msg_pos.data_pos = 0;
+        }
+
+        /* 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;
+        }
+#ifdef CONFIG_BLOCK
+        if (m->bio && !m->bio_iter)
+                init_bio_iter(m->bio, &m->bio_iter, &m->bio_seg);
+#endif
+
+        /* (page) data */
+        while (con->in_msg_pos.data_pos < data_len) {
+                if (m->pages) {
+                        ret = read_partial_message_pages(con, m->pages,
+                                                 data_len, datacrc);
+                        if (ret <= 0)
+                                return ret;
+#ifdef CONFIG_BLOCK
+                } else if (m->bio) {
+
+                        ret = read_partial_message_bio(con,
+                                                 &m->bio_iter, &m->bio_seg,
+                                                 data_len, datacrc);
+                        if (ret <= 0)
+                                return ret;
+#endif
+                } else {
+                        BUG_ON(1);
+                }
+        }
+
+        /* footer */
+        to = sizeof(m->hdr) + sizeof(m->footer);
+        while (con->in_base_pos < to) {
+                left = to - con->in_base_pos;
+                ret = ceph_tcp_recvmsg(con->sock, (char *)&m->footer +
+                                       (con->in_base_pos - sizeof(m->hdr)),
+                                       left);
+                if (ret <= 0)
+                        return ret;
+                con->in_base_pos += ret;
+        }
+        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 (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;
+        }
+
+        return 1; /* done! */
+}
+
+/*
+ * Process message.  This happens in the worker thread.  The callback should
+ * be careful not to do anything that waits on other incoming messages or it
+ * may deadlock.
+ */
+static void process_message(struct ceph_connection *con)
+{
+        struct ceph_msg *msg;
+
+        msg = con->in_msg;
+        con->in_msg = NULL;
+
+        /* if first message, set peer_name */
+        if (con->peer_name.type == 0)
+                con->peer_name = msg->hdr.src;
+
+        con->in_seq++;
+        mutex_unlock(&con->mutex);
+
+        dout("===== %p %llu from %s%lld %d=%s len %d+%d (%u %u %u) =====\n",
+             msg, le64_to_cpu(msg->hdr.seq),
+             ENTITY_NAME(msg->hdr.src),
+             le16_to_cpu(msg->hdr.type),
+             ceph_msg_type_name(le16_to_cpu(msg->hdr.type)),
+             le32_to_cpu(msg->hdr.front_len),
+             le32_to_cpu(msg->hdr.data_len),
+             con->in_front_crc, con->in_middle_crc, con->in_data_crc);
+        con->ops->dispatch(con, msg);
+
+        mutex_lock(&con->mutex);
+        prepare_read_tag(con);
+}
+
+
+/*
+ * Write something to the socket.  Called in a worker thread when the
+ * socket appears to be writeable and we have something ready to send.
+ */
+static int try_write(struct ceph_connection *con)
+{
+        struct ceph_messenger *msgr = con->msgr;
+        int ret = 1;
+
+        dout("try_write start %p state %lu nref %d\n", con, con->state,
+             atomic_read(&con->nref));
+
+more:
+        dout("try_write out_kvec_bytes %d\n", con->out_kvec_bytes);
+
+        /* open the socket first? */
+        if (con->sock == NULL) {
+                /*
+                 * if we were STANDBY and are reconnecting _this_
+                 * connection, bump connect_seq now.  Always bump
+                 * global_seq.
+                 */
+                if (test_and_clear_bit(STANDBY, &con->state))
+                        con->connect_seq++;
+
+                prepare_write_banner(msgr, con);
+                prepare_write_connect(msgr, con, 1);
+                prepare_read_banner(con);
+                set_bit(CONNECTING, &con->state);
+                clear_bit(NEGOTIATING, &con->state);
+
+                BUG_ON(con->in_msg);
+                con->in_tag = CEPH_MSGR_TAG_READY;
+                dout("try_write initiating connect on %p new state %lu\n",
+                     con, con->state);
+                con->sock = ceph_tcp_connect(con);
+                if (IS_ERR(con->sock)) {
+                        con->sock = NULL;
+                        con->error_msg = "connect error";
+                        ret = -1;
+                        goto out;
+                }
+        }
+
+more_kvec:
+        /* kvec data queued? */
+        if (con->out_skip) {
+                ret = write_partial_skip(con);
+                if (ret <= 0)
+                        goto done;
+                if (ret < 0) {
+                        dout("try_write write_partial_skip err %d\n", ret);
+                        goto done;
+                }
+        }
+        if (con->out_kvec_left) {
+                ret = write_partial_kvec(con);
+                if (ret <= 0)
+                        goto done;
+        }
+
+        /* msg pages? */
+        if (con->out_msg) {
+                if (con->out_msg_done) {
+                        ceph_msg_put(con->out_msg);
+                        con->out_msg = NULL;   /* we're done with this one */
+                        goto do_next;
+                }
+
+                ret = write_partial_msg_pages(con);
+                if (ret == 1)
+                        goto more_kvec;  /* we need to send the footer, too! */
+                if (ret == 0)
+                        goto done;
+                if (ret < 0) {
+                        dout("try_write write_partial_msg_pages err %d\n",
+                             ret);
+                        goto done;
+                }
+        }
+
+do_next:
+        if (!test_bit(CONNECTING, &con->state)) {
+                /* is anything else pending? */
+                if (!list_empty(&con->out_queue)) {
+                        prepare_write_message(con);
+                        goto more;
+                }
+                if (con->in_seq > con->in_seq_acked) {
+                        prepare_write_ack(con);
+                        goto more;
+                }
+                if (test_and_clear_bit(KEEPALIVE_PENDING, &con->state)) {
+                        prepare_write_keepalive(con);
+                        goto more;
+                }
+        }
+
+        /* Nothing to do! */
+        clear_bit(WRITE_PENDING, &con->state);
+        dout("try_write nothing else to write.\n");
+done:
+        ret = 0;
+out:
+        dout("try_write done on %p\n", con);
+        return ret;
+}
+
+
+
+/*
+ * Read what we can from the socket.
+ */
+static int try_read(struct ceph_connection *con)
+{
+        int ret = -1;
+
+        if (!con->sock)
+                return 0;
+
+        if (test_bit(STANDBY, &con->state))
+                return 0;
+
+        dout("try_read start on %p\n", con);
+
+more:
+        dout("try_read tag %d in_base_pos %d\n", (int)con->in_tag,
+             con->in_base_pos);
+        if (test_bit(CONNECTING, &con->state)) {
+                if (!test_bit(NEGOTIATING, &con->state)) {
+                        dout("try_read connecting\n");
+                        ret = read_partial_banner(con);
+                        if (ret <= 0)
+                                goto done;
+                        if (process_banner(con) < 0) {
+                                ret = -1;
+                                goto out;
+                        }
+                }
+                ret = read_partial_connect(con);
+                if (ret <= 0)
+                        goto done;
+                if (process_connect(con) < 0) {
+                        ret = -1;
+                        goto out;
+                }
+                goto more;
+        }
+
+        if (con->in_base_pos < 0) {
+                /*
+                 * skipping + discarding content.
+                 *
+                 * FIXME: there must be a better way to do this!
+                 */
+                static char buf[1024];
+                int skip = min(1024, -con->in_base_pos);
+                dout("skipping %d / %d bytes\n", skip, -con->in_base_pos);
+                ret = ceph_tcp_recvmsg(con->sock, buf, skip);
+                if (ret <= 0)
+                        goto done;
+                con->in_base_pos += ret;
+                if (con->in_base_pos)
+                        goto more;
+        }
+        if (con->in_tag == CEPH_MSGR_TAG_READY) {
+                /*
+                 * what's next?
+                 */
+                ret = ceph_tcp_recvmsg(con->sock, &con->in_tag, 1);
+                if (ret <= 0)
+                        goto done;
+                dout("try_read got tag %d\n", (int)con->in_tag);
+                switch (con->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_CLOSE:
+                        set_bit(CLOSED, &con->state);   /* fixme */
+                        goto done;
+                default:
+                        goto bad_tag;
+                }
+        }
+        if (con->in_tag == CEPH_MSGR_TAG_MSG) {
+                ret = read_partial_message(con);
+                if (ret <= 0) {
+                        switch (ret) {
+                        case -EBADMSG:
+                                con->error_msg = "bad crc";
+                                ret = -EIO;
+                                goto out;
+                        case -EIO:
+                                con->error_msg = "io error";
+                                goto out;
+                        default:
+                                goto done;
+                        }
+                }
+                if (con->in_tag == CEPH_MSGR_TAG_READY)
+                        goto more;
+                process_message(con);
+                goto more;
+        }
+        if (con->in_tag == CEPH_MSGR_TAG_ACK) {
+                ret = read_partial_ack(con);
+                if (ret <= 0)
+                        goto done;
+                process_ack(con);
+                goto more;
+        }
+
+done:
+        ret = 0;
+out:
+        dout("try_read done on %p\n", con);
+        return ret;
+
+bad_tag:
+        pr_err("try_read bad con->in_tag = %d\n", (int)con->in_tag);
+        con->error_msg = "protocol error, garbage tag";
+        ret = -1;
+        goto out;
+}
+
+
+/*
+ * Atomically queue work on a connection.  Bump @con reference to
+ * avoid races with connection teardown.
+ *
+ * There is some trickery going on with QUEUED and BUSY because we
+ * only want a _single_ thread operating on each connection at any
+ * point in time, but we want to use all available CPUs.
+ *
+ * The worker thread only proceeds if it can atomically set BUSY.  It
+ * clears QUEUED and does it's thing.  When it thinks it's done, it
+ * clears BUSY, then rechecks QUEUED.. if it's set again, it loops
+ * (tries again to set BUSY).
+ *
+ * To queue work, we first set QUEUED, _then_ if BUSY isn't set, we
+ * try to queue work.  If that fails (work is already queued, or BUSY)
+ * we give up (work also already being done or is queued) but leave QUEUED
+ * set so that the worker thread will loop if necessary.
+ */
+static void queue_con(struct ceph_connection *con)
+{
+        if (test_bit(DEAD, &con->state)) {
+                dout("queue_con %p ignoring: DEAD\n",
+                     con);
+                return;
+        }
+
+        if (!con->ops->get(con)) {
+                dout("queue_con %p ref count 0\n", con);
+                return;
+        }
+
+        set_bit(QUEUED, &con->state);
+        if (test_bit(BUSY, &con->state)) {
+                dout("queue_con %p - already BUSY\n", con);
+                con->ops->put(con);
+        } else if (!queue_work(ceph_msgr_wq, &con->work.work)) {
+                dout("queue_con %p - already queued\n", con);
+                con->ops->put(con);
+        } else {
+                dout("queue_con %p\n", con);
+        }
+}
+
+/*
+ * Do some work on a connection.  Drop a connection ref when we're done.
+ */
+static void con_work(struct work_struct *work)
+{
+        struct ceph_connection *con = container_of(work, struct ceph_connection,
+                                                   work.work);
+        int backoff = 0;
+
+more:
+        if (test_and_set_bit(BUSY, &con->state) != 0) {
+                dout("con_work %p BUSY already set\n", con);
+                goto out;
+        }
+        dout("con_work %p start, clearing QUEUED\n", con);
+        clear_bit(QUEUED, &con->state);
+
+        mutex_lock(&con->mutex);
+
+        if (test_bit(CLOSED, &con->state)) { /* e.g. if we are replaced */
+                dout("con_work CLOSED\n");
+                con_close_socket(con);
+                goto done;
+        }
+        if (test_and_clear_bit(OPENING, &con->state)) {
+                /* reopen w/ new peer */
+                dout("con_work OPENING\n");
+                con_close_socket(con);
+        }
+
+        if (test_and_clear_bit(SOCK_CLOSED, &con->state) ||
+            try_read(con) < 0 ||
+            try_write(con) < 0) {
+                mutex_unlock(&con->mutex);
+                backoff = 1;
+                ceph_fault(con);     /* error/fault path */
+                goto done_unlocked;
+        }
+
+done:
+        mutex_unlock(&con->mutex);
+
+done_unlocked:
+        clear_bit(BUSY, &con->state);
+        dout("con->state=%lu\n", con->state);
+        if (test_bit(QUEUED, &con->state)) {
+                if (!backoff || test_bit(OPENING, &con->state)) {
+                        dout("con_work %p QUEUED reset, looping\n", con);
+                        goto more;
+                }
+                dout("con_work %p QUEUED reset, but just faulted\n", con);
+                clear_bit(QUEUED, &con->state);
+        }
+        dout("con_work %p done\n", con);
+
+out:
+        con->ops->put(con);
+}
+
+
+/*
+ * Generic error/fault handler.  A retry mechanism is used with
+ * exponential backoff
+ */
+static void ceph_fault(struct ceph_connection *con)
+{
+        pr_err("%s%lld %s %s\n", ENTITY_NAME(con->peer_name),
+               ceph_pr_addr(&con->peer_addr.in_addr), con->error_msg);
+        dout("fault %p state %lu to peer %s\n",
+             con, con->state, ceph_pr_addr(&con->peer_addr.in_addr));
+
+        if (test_bit(LOSSYTX, &con->state)) {
+                dout("fault on LOSSYTX channel\n");
+                goto out;
+        }
+
+        mutex_lock(&con->mutex);
+        if (test_bit(CLOSED, &con->state))
+                goto out_unlock;
+
+        con_close_socket(con);
+
+        if (con->in_msg) {
+                ceph_msg_put(con->in_msg);
+                con->in_msg = NULL;
+        }
+
+        /* Requeue anything that hasn't been acked */
+        list_splice_init(&con->out_sent, &con->out_queue);
+
+        /* If there are no messages in the queue, place the connection
+         * in a STANDBY state (i.e., don't try to reconnect just yet). */
+        if (list_empty(&con->out_queue) && !con->out_keepalive_pending) {
+                dout("fault setting STANDBY\n");
+                set_bit(STANDBY, &con->state);
+        } else {
+                /* retry after a delay. */
+                if (con->delay == 0)
+                        con->delay = BASE_DELAY_INTERVAL;
+                else if (con->delay < MAX_DELAY_INTERVAL)
+                        con->delay *= 2;
+                dout("fault queueing %p delay %lu\n", con, con->delay);
+                con->ops->get(con);
+                if (queue_delayed_work(ceph_msgr_wq, &con->work,
+                                       round_jiffies_relative(con->delay)) == 0)
+                        con->ops->put(con);
+        }
+
+out_unlock:
+        mutex_unlock(&con->mutex);
+out:
+        /*
+         * in case we faulted due to authentication, invalidate our
+         * current tickets so that we can get new ones.
+         */
+        if (con->auth_retry && con->ops->invalidate_authorizer) {
+                dout("calling invalidate_authorizer()\n");
+                con->ops->invalidate_authorizer(con);
+        }
+
+        if (con->ops->fault)
+                con->ops->fault(con);
+}
+
+
+
+/*
+ * create a new messenger instance
+ */
+struct ceph_messenger *ceph_messenger_create(struct ceph_entity_addr *myaddr,
+                                             u32 supported_features,
+                                             u32 required_features)
+{
+        struct ceph_messenger *msgr;
+
+        msgr = kzalloc(sizeof(*msgr), GFP_KERNEL);
+        if (msgr == NULL)
+                return ERR_PTR(-ENOMEM);
+
+        msgr->supported_features = supported_features;
+        msgr->required_features = required_features;
+
+        spin_lock_init(&msgr->global_seq_lock);
+
+        /* the zero page is needed if a request is "canceled" while the message
+         * is being written over the socket */
+        msgr->zero_page = __page_cache_alloc(GFP_KERNEL | __GFP_ZERO);
+        if (!msgr->zero_page) {
+                kfree(msgr);
+                return ERR_PTR(-ENOMEM);
+        }
+        kmap(msgr->zero_page);
+
+        if (myaddr)
+                msgr->inst.addr = *myaddr;
+
+        /* select a random nonce */
+        msgr->inst.addr.type = 0;
+        get_random_bytes(&msgr->inst.addr.nonce, sizeof(msgr->inst.addr.nonce));
+        encode_my_addr(msgr);
+
+        dout("messenger_create %p\n", msgr);
+        return msgr;
+}
+EXPORT_SYMBOL(ceph_messenger_create);
+
+void ceph_messenger_destroy(struct ceph_messenger *msgr)
+{
+        dout("destroy %p\n", msgr);
+        kunmap(msgr->zero_page);
+        __free_page(msgr->zero_page);
+        kfree(msgr);
+        dout("destroyed messenger %p\n", msgr);
+}
+EXPORT_SYMBOL(ceph_messenger_destroy);
+
+/*
+ * Queue up an outgoing message on the given connection.
+ */
+void ceph_con_send(struct ceph_connection *con, struct ceph_msg *msg)
+{
+        if (test_bit(CLOSED, &con->state)) {
+                dout("con_send %p closed, dropping %p\n", con, msg);
+                ceph_msg_put(msg);
+                return;
+        }
+
+        /* set src+dst */
+        msg->hdr.src = con->msgr->inst.name;
+
+        BUG_ON(msg->front.iov_len != le32_to_cpu(msg->hdr.front_len));
+
+        msg->needs_out_seq = true;
+
+        /* queue */
+        mutex_lock(&con->mutex);
+        BUG_ON(!list_empty(&msg->list_head));
+        list_add_tail(&msg->list_head, &con->out_queue);
+        dout("----- %p to %s%lld %d=%s len %d+%d+%d -----\n", msg,
+             ENTITY_NAME(con->peer_name), le16_to_cpu(msg->hdr.type),
+             ceph_msg_type_name(le16_to_cpu(msg->hdr.type)),
+             le32_to_cpu(msg->hdr.front_len),
+             le32_to_cpu(msg->hdr.middle_len),
+             le32_to_cpu(msg->hdr.data_len));
+        mutex_unlock(&con->mutex);
+
+        /* if there wasn't anything waiting to send before, queue
+         * new work */
+        if (test_and_set_bit(WRITE_PENDING, &con->state) == 0)
+                queue_con(con);
+}
+EXPORT_SYMBOL(ceph_con_send);
+
+/*
+ * Revoke a message that was previously queued for send
+ */
+void ceph_con_revoke(struct ceph_connection *con, struct ceph_msg *msg)
+{
+        mutex_lock(&con->mutex);
+        if (!list_empty(&msg->list_head)) {
+                dout("con_revoke %p msg %p - was on queue\n", con, msg);
+                list_del_init(&msg->list_head);
+                ceph_msg_put(msg);
+                msg->hdr.seq = 0;
+        }
+        if (con->out_msg == msg) {
+                dout("con_revoke %p msg %p - was sending\n", con, msg);
+                con->out_msg = NULL;
+                if (con->out_kvec_is_msg) {
+                        con->out_skip = con->out_kvec_bytes;
+                        con->out_kvec_is_msg = false;
+                }
+                ceph_msg_put(msg);
+                msg->hdr.seq = 0;
+        }
+        mutex_unlock(&con->mutex);
+}
+
+/*
+ * Revoke a message that we may be reading data into
+ */
+void ceph_con_revoke_message(struct ceph_connection *con, struct ceph_msg *msg)
+{
+        mutex_lock(&con->mutex);
+        if (con->in_msg && con->in_msg == msg) {
+                unsigned front_len = le32_to_cpu(con->in_hdr.front_len);
+                unsigned middle_len = le32_to_cpu(con->in_hdr.middle_len);
+                unsigned data_len = le32_to_cpu(con->in_hdr.data_len);
+
+                /* skip rest of message */
+                dout("con_revoke_pages %p msg %p revoked\n", con, msg);
+                        con->in_base_pos = con->in_base_pos -
+                                sizeof(struct ceph_msg_header) -
+                                front_len -
+                                middle_len -
+                                data_len -
+                                sizeof(struct ceph_msg_footer);
+                ceph_msg_put(con->in_msg);
+                con->in_msg = NULL;
+                con->in_tag = CEPH_MSGR_TAG_READY;
+                con->in_seq++;
+        } else {
+                dout("con_revoke_pages %p msg %p pages %p no-op\n",
+                     con, con->in_msg, msg);
+        }
+        mutex_unlock(&con->mutex);
+}
+
+/*
+ * Queue a keepalive byte to ensure the tcp connection is alive.
+ */
+void ceph_con_keepalive(struct ceph_connection *con)
+{
+        if (test_and_set_bit(KEEPALIVE_PENDING, &con->state) == 0 &&
+            test_and_set_bit(WRITE_PENDING, &con->state) == 0)
+                queue_con(con);
+}
+EXPORT_SYMBOL(ceph_con_keepalive);
+
+
+/*
+ * construct a new message with given type, size
+ * the new msg has a ref count of 1.
+ */
+struct ceph_msg *ceph_msg_new(int type, int front_len, gfp_t flags)
+{
+        struct ceph_msg *m;
+
+        m = kmalloc(sizeof(*m), flags);
+        if (m == NULL)
+                goto out;
+        kref_init(&m->kref);
+        INIT_LIST_HEAD(&m->list_head);
+
+        m->hdr.tid = 0;
+        m->hdr.type = cpu_to_le16(type);
+        m->hdr.priority = cpu_to_le16(CEPH_MSG_PRIO_DEFAULT);
+        m->hdr.version = 0;
+        m->hdr.front_len = cpu_to_le32(front_len);
+        m->hdr.middle_len = 0;
+        m->hdr.data_len = 0;
+        m->hdr.data_off = 0;
+        m->hdr.reserved = 0;
+        m->footer.front_crc = 0;
+        m->footer.middle_crc = 0;
+        m->footer.data_crc = 0;
+        m->footer.flags = 0;
+        m->front_max = front_len;
+        m->front_is_vmalloc = false;
+        m->more_to_follow = false;
+        m->pool = NULL;
+
+        /* front */
+        if (front_len) {
+                if (front_len > PAGE_CACHE_SIZE) {
+                        m->front.iov_base = __vmalloc(front_len, flags,
+                                                      PAGE_KERNEL);
+                        m->front_is_vmalloc = true;
+                } else {
+                        m->front.iov_base = kmalloc(front_len, flags);
+                }
+                if (m->front.iov_base == NULL) {
+                        pr_err("msg_new can't allocate %d bytes\n",
+                             front_len);
+                        goto out2;
+                }
+        } else {
+                m->front.iov_base = NULL;
+        }
+        m->front.iov_len = front_len;
+
+        /* middle */
+        m->middle = NULL;
+
+        /* data */
+        m->nr_pages = 0;
+        m->pages = NULL;
+        m->pagelist = NULL;
+        m->bio = NULL;
+        m->bio_iter = NULL;
+        m->bio_seg = 0;
+        m->trail = NULL;
+
+        dout("ceph_msg_new %p front %d\n", m, front_len);
+        return m;
+
+out2:
+        ceph_msg_put(m);
+out:
+        pr_err("msg_new can't create type %d front %d\n", type, front_len);
+        return NULL;
+}
+EXPORT_SYMBOL(ceph_msg_new);
+
+/*
+ * Allocate "middle" portion of a message, if it is needed and wasn't
+ * allocated by alloc_msg.  This allows us to read a small fixed-size
+ * per-type header in the front and then gracefully fail (i.e.,
+ * propagate the error to the caller based on info in the front) when
+ * the middle is too large.
+ */
+static int ceph_alloc_middle(struct ceph_connection *con, struct ceph_msg *msg)
+{
+        int type = le16_to_cpu(msg->hdr.type);
+        int middle_len = le32_to_cpu(msg->hdr.middle_len);
+
+        dout("alloc_middle %p type %d %s middle_len %d\n", msg, type,
+             ceph_msg_type_name(type), middle_len);
+        BUG_ON(!middle_len);
+        BUG_ON(msg->middle);
+
+        msg->middle = ceph_buffer_new(middle_len, GFP_NOFS);
+        if (!msg->middle)
+                return -ENOMEM;
+        return 0;
+}
+
+/*
+ * Generic message allocator, for incoming messages.
+ */
+static struct ceph_msg *ceph_alloc_msg(struct ceph_connection *con,
+                                struct ceph_msg_header *hdr,
+                                int *skip)
+{
+        int type = le16_to_cpu(hdr->type);
+        int front_len = le32_to_cpu(hdr->front_len);
+        int middle_len = le32_to_cpu(hdr->middle_len);
+        struct ceph_msg *msg = NULL;
+        int ret;
+
+        if (con->ops->alloc_msg) {
+                mutex_unlock(&con->mutex);
+                msg = con->ops->alloc_msg(con, hdr, skip);
+                mutex_lock(&con->mutex);
+                if (!msg || *skip)
+                        return NULL;
+        }
+        if (!msg) {
+                *skip = 0;
+                msg = ceph_msg_new(type, front_len, GFP_NOFS);
+                if (!msg) {
+                        pr_err("unable to allocate msg type %d len %d\n",
+                               type, front_len);
+                        return NULL;
+                }
+        }
+        memcpy(&msg->hdr, &con->in_hdr, sizeof(con->in_hdr));
+
+        if (middle_len && !msg->middle) {
+                ret = ceph_alloc_middle(con, msg);
+                if (ret < 0) {
+                        ceph_msg_put(msg);
+                        return NULL;
+                }
+        }
+
+        return msg;
+}
+
+
+/*
+ * Free a generically kmalloc'd message.
+ */
+void ceph_msg_kfree(struct ceph_msg *m)
+{
+        dout("msg_kfree %p\n", m);
+        if (m->front_is_vmalloc)
+                vfree(m->front.iov_base);
+        else
+                kfree(m->front.iov_base);
+        kfree(m);
+}
+
+/*
+ * Drop a msg ref.  Destroy as needed.
+ */
+void ceph_msg_last_put(struct kref *kref)
+{
+        struct ceph_msg *m = container_of(kref, struct ceph_msg, kref);
+
+        dout("ceph_msg_put last one on %p\n", m);
+        WARN_ON(!list_empty(&m->list_head));
+
+        /* drop middle, data, if any */
+        if (m->middle) {
+                ceph_buffer_put(m->middle);
+                m->middle = NULL;
+        }
+        m->nr_pages = 0;
+        m->pages = NULL;
+
+        if (m->pagelist) {
+                ceph_pagelist_release(m->pagelist);
+                kfree(m->pagelist);
+                m->pagelist = NULL;
+        }
+
+        m->trail = NULL;
+
+        if (m->pool)
+                ceph_msgpool_put(m->pool, m);
+        else
+                ceph_msg_kfree(m);
+}
+EXPORT_SYMBOL(ceph_msg_last_put);
+
+void ceph_msg_dump(struct ceph_msg *msg)
+{
+        pr_debug("msg_dump %p (front_max %d nr_pages %d)\n", msg,
+                 msg->front_max, msg->nr_pages);
+        print_hex_dump(KERN_DEBUG, "header: ",
+                       DUMP_PREFIX_OFFSET, 16, 1,
+                       &msg->hdr, sizeof(msg->hdr), true);
+        print_hex_dump(KERN_DEBUG, " front: ",
+                       DUMP_PREFIX_OFFSET, 16, 1,
+                       msg->front.iov_base, msg->front.iov_len, true);
+        if (msg->middle)
+                print_hex_dump(KERN_DEBUG, "middle: ",
+                               DUMP_PREFIX_OFFSET, 16, 1,
+                               msg->middle->vec.iov_base,
+                               msg->middle->vec.iov_len, true);
+        print_hex_dump(KERN_DEBUG, "footer: ",
+                       DUMP_PREFIX_OFFSET, 16, 1,
+                       &msg->footer, sizeof(msg->footer), true);
+}
+EXPORT_SYMBOL(ceph_msg_dump);