[2/7] dst: network state machine.

Evgeniy Polyakov
2009-01-13T23:12:54Z

Each DST device contains of two nodes: local and remote (called also as export node).
This patch contains local node processing engine: network state storage,
socket processing loops and state machine, socket polling machinery, reconnection
logic, send/receive basic helpers, related IO commands and so on.

Signed-off-by: Evgeniy Polyakov <zbr@ioremap.net>

diff --git a/drivers/staging/dst/state.c b/drivers/staging/dst/state.c
new file mode 100644
index 0000000..7243d37
--- /dev/null
+++ b/drivers/staging/dst/state.c
@@ -0,0 +1,839 @@
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/blkdev.h>
+#include <linux/bio.h>
+#include <linux/connector.h>
+#include <linux/dst.h>
+#include <linux/device.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/socket.h>
+#include <linux/slab.h>
+
+#include <net/sock.h>
+
+/*
+ * Polling machinery.
+ */
+
+struct dst_poll_helper
+{
+ poll_table pt;
+ struct dst_state *st;
+};
+
+static int dst_queue_wake(wait_queue_t *wait, unsigned mode, int sync, void *key)
+{
+ struct dst_state *st = container_of(wait, struct dst_state, wait);
+
+ wake_up(&st->thread_wait);
+ return 1;
+}
+
+static void dst_queue_func(struct file *file, wait_queue_head_t *whead,
+ poll_table *pt)
+{
+ struct dst_state *st = container_of(pt, struct dst_poll_helper, pt)->st;
+
+ st->whead = whead;
+ init_waitqueue_func_entry(&st->wait, dst_queue_wake);
+ add_wait_queue(whead, &st->wait);
+}
+
+void dst_poll_exit(struct dst_state *st)
+{
+ if (st->whead) {
+ remove_wait_queue(st->whead, &st->wait);
+ st->whead = NULL;
+ }
+}
+
+int dst_poll_init(struct dst_state *st)
+{
+ struct dst_poll_helper ph;
+
+ ph.st = st;
+ init_poll_funcptr(&ph.pt, &dst_queue_func);
+
+ st->socket->ops->poll(NULL, st->socket, &ph.pt);
+ return 0;
+}
+
+/*
+ * Header receiving function - may block.
+ */
+static int dst_data_recv_header(struct socket *sock,
+ void *data, unsigned int size, int block)
+{
+ struct msghdr msg;
+ struct kvec iov;
+ int err;
+
+ iov.iov_base = data;
+ iov.iov_len = size;
+
+ msg.msg_iov = (struct iovec *)&iov;
+ msg.msg_iovlen = 1;
+ msg.msg_name = NULL;
+ msg.msg_namelen = 0;
+ msg.msg_control = NULL;
+ msg.msg_controllen = 0;
+ msg.msg_flags = (block)?MSG_WAITALL:MSG_DONTWAIT;
+
+ err = kernel_recvmsg(sock, &msg, &iov, 1, iov.iov_len,
+ msg.msg_flags);
+ if (err != size)
+ return -1;
+
+ return 0;
+}
+
+/*
+ * Header sending function - may block.
+ */
+int dst_data_send_header(struct socket *sock,
+ void *data, unsigned int size, int more)
+{
+ struct msghdr msg;
+ struct kvec iov;
+ int err;
+
+ iov.iov_base = data;
+ iov.iov_len = size;
+
+ msg.msg_iov = (struct iovec *)&iov;
+ msg.msg_iovlen = 1;
+ msg.msg_name = NULL;
+ msg.msg_namelen = 0;
+ msg.msg_control = NULL;
+ msg.msg_controllen = 0;
+ msg.msg_flags = MSG_WAITALL | (more)?MSG_MORE:0;
+
+ err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
+ if (err != size) {
+ dprintk("%s: size: %u, more: %d, err: %d.\n",
+ __func__, size, more, err);
+ return -1;
+ }
+
+ return 0;
+}
+
+/*
+ * Block autoconfiguration: request size of the storage and permissions.
+ */
+static int dst_request_remote_config(struct dst_state *st)
+{
+ struct dst_node *n = st->node;
+ int err = -EINVAL;
+ struct dst_cmd *cmd = st->data;
+
+ memset(cmd, 0, sizeof(struct dst_cmd));
+ cmd->cmd = DST_CFG;
+
+ dst_convert_cmd(cmd);
+
+ err = dst_data_send_header(st->socket, cmd, sizeof(struct dst_cmd), 0);
+ if (err)
+ goto out;
+
+ err = dst_data_recv_header(st->socket, cmd, sizeof(struct dst_cmd), 1);
+ if (err)
+ goto out;
+
+ dst_convert_cmd(cmd);
+
+ if (cmd->cmd != DST_CFG) {
+ err = -EINVAL;
+ dprintk("%s: checking result: cmd: %d, size reported: %llu.\n",
+ __func__, cmd->cmd, cmd->sector);
+ goto out;
+ }
+
+ if (n->size != 0)
+ n->size = min_t(loff_t, n->size, cmd->sector);
+ else
+ n->size = cmd->sector;
+
+ n->info->size = n->size;
+ st->permissions = cmd->rw;
+
+out:
+ dprintk("%s: n: %p, err: %d, size: %llu, permission: %x.\n",
+ __func__, n, err, n->size, st->permissions);
+ return err;
+}
+
+/*
+ * Socket machinery.
+ */
+
+#define DST_DEFAULT_TIMEO 20000
+
+int dst_state_socket_create(struct dst_state *st)
+{
+ int err;
+ struct socket *sock;
+ struct dst_network_ctl *ctl = &st->ctl;
+
+ err = sock_create(ctl->addr.sa_family, ctl->type, ctl->proto, &sock);
+ if (err < 0)
+ return err;
+
+ sock->sk->sk_sndtimeo = sock->sk->sk_rcvtimeo =
+ msecs_to_jiffies(DST_DEFAULT_TIMEO);
+ sock->sk->sk_allocation = GFP_NOIO;
+
+ st->socket = st->read_socket = sock;
+ return 0;
+}
+
+void dst_state_socket_release(struct dst_state *st)
+{
+ dprintk("%s: st: %p, socket: %p, n: %p.\n",
+ __func__, st, st->socket, st->node);
+ if (st->socket) {
+ sock_release(st->socket);
+ st->socket = NULL;
+ st->read_socket = NULL;
+ }
+}
+
+void dst_dump_addr(struct socket *sk, struct sockaddr *sa, char *str)
+{
+ if (sk->ops->family == AF_INET) {
+ struct sockaddr_in *sin = (struct sockaddr_in *)sa;
+ printk(KERN_INFO "%s %u.%u.%u.%u:%d.\n",
+ str, NIPQUAD(sin->sin_addr.s_addr), ntohs(sin->sin_port));
+ } else if (sk->ops->family == AF_INET6) {
+ struct sockaddr_in6 *sin = (struct sockaddr_in6 *)sa;
+ printk(KERN_INFO "%s %pi6:%d",
+ str, &sin->sin6_addr, ntohs(sin->sin6_port));
+ }
+}
+
+void dst_state_exit_connected(struct dst_state *st)
+{
+ if (st->socket) {
+ dst_poll_exit(st);
+ st->socket->ops->shutdown(st->socket, 2);
+
+ dst_dump_addr(st->socket, (struct sockaddr *)&st->ctl.addr,
+ "Disconnected peer");
+ dst_state_socket_release(st);
+ }
+}
+
+static int dst_state_init_connected(struct dst_state *st)
+{
+ int err;
+ struct dst_network_ctl *ctl = &st->ctl;
+
+ err = dst_state_socket_create(st);
+ if (err)
+ goto err_out_exit;
+
+ err = kernel_connect(st->socket, (struct sockaddr *)&st->ctl.addr,
+ st->ctl.addr.sa_data_len, 0);
+ if (err)
+ goto err_out_release;
+
+ err = dst_poll_init(st);
+ if (err)
+ goto err_out_release;
+
+ dst_dump_addr(st->socket, (struct sockaddr *)&ctl->addr,
+ "Connected to peer");
+
+ return 0;
+
+err_out_release:
+ dst_state_socket_release(st);
+err_out_exit:
+ return err;
+}
+
+/*
+ * State reset is used to reconnect to the remote peer.
+ * May fail, but who cares, we will try again later.
+ */
+static void inline dst_state_reset_nolock(struct dst_state *st)
+{
+ dst_state_exit_connected(st);
+ dst_state_init_connected(st);
+}
+
+static void inline dst_state_reset(struct dst_state *st)
+{
+ dst_state_lock(st);
+ dst_state_reset_nolock(st);
+ dst_state_unlock(st);
+}
+
+/*
+ * Basic network sending/receiving functions.
+ * Blocked mode is used.
+ */
+static int dst_data_recv_raw(struct dst_state *st, void *buf, u64 size)
+{
+ struct msghdr msg;
+ struct kvec iov;
+ int err;
+
+ BUG_ON(!size);
+
+ iov.iov_base = buf;
+ iov.iov_len = size;
+
+ msg.msg_iov = (struct iovec *)&iov;
+ msg.msg_iovlen = 1;
+ msg.msg_name = NULL;
+ msg.msg_namelen = 0;
+ msg.msg_control = NULL;
+ msg.msg_controllen = 0;
+ msg.msg_flags = MSG_DONTWAIT;
+
+ err = kernel_recvmsg(st->socket, &msg, &iov, 1, iov.iov_len,
+ msg.msg_flags);
+ if (err <= 0) {
+ dprintk("%s: failed to recv data: size: %llu, err: %d.\n",
+ __func__, size, err);
+ if (err == 0)
+ err = -ECONNRESET;
+
+ dst_state_exit_connected(st);
+ }
+
+ return err;
+}
+
+/*
+ * Ping command to early detect failed nodes.
+ */
+static int dst_send_ping(struct dst_state *st)
+{
+ struct dst_cmd *cmd = st->data;
+ int err = -ECONNRESET;
+
+ dst_state_lock(st);
+ if (st->socket) {
+ memset(cmd, 0, sizeof(struct dst_cmd));
+
+ cmd->cmd = __cpu_to_be32(DST_PING);
+
+ err = dst_data_send_header(st->socket, cmd, sizeof(struct dst_cmd), 0);
+ }
+ dprintk("%s: st: %p, socket: %p, err: %d.\n", __func__, st, st->socket, err);
+ dst_state_unlock(st);
+
+ return err;
+}
+
+/*
+ * Receiving function, which should either return error or read
+ * whole block request. If there was no traffic for a one second,
+ * send a ping, since remote node may die.
+ */
+int dst_data_recv(struct dst_state *st, void *data, unsigned int size)
+{
+ unsigned int revents = 0;
+ unsigned int err_mask = POLLERR | POLLHUP | POLLRDHUP;
+ unsigned int mask = err_mask | POLLIN;
+ struct dst_node *n = st->node;
+ int err = 0;
+
+ while (size && !err) {
+ revents = dst_state_poll(st);
+
+ if (!(revents & mask)) {
+ DEFINE_WAIT(wait);
+
+ for (;;) {
+ prepare_to_wait(&st->thread_wait, &wait,
+ TASK_INTERRUPTIBLE);
+ if (!n->trans_scan_timeout || st->need_exit)
+ break;
+
+ revents = dst_state_poll(st);
+
+ if (revents & mask)
+ break;
+
+ if (signal_pending(current))
+ break;
+
+ if (!schedule_timeout(HZ)) {
+ err = dst_send_ping(st);
+ if (err)
+ return err;
+ }
+
+ continue;
+ }
+ finish_wait(&st->thread_wait, &wait);
+ }
+
+ err = -ECONNRESET;
+ dst_state_lock(st);
+
+ if ( st->socket &&
+ (st->read_socket == st->socket) &&
+ (revents & POLLIN)) {
+ err = dst_data_recv_raw(st, data, size);
+ if (err > 0) {
+ data += err;
+ size -= err;
+ err = 0;
+ }
+ }
+
+ if (revents & err_mask || !st->socket) {
+ dprintk("%s: revents: %x, socket: %p, size: %u, err: %d.\n",
+ __func__, revents, st->socket, size, err);
+ err = -ECONNRESET;
+ }
+
+ dst_state_unlock(st);
+
+ if (!n->trans_scan_timeout)
+ err = -ENODEV;
+ }
+
+ return err;
+}
+
+/*
+ * Send block autoconf reply.
+ */
+static int dst_process_cfg(struct dst_state *st)
+{
+ struct dst_node *n = st->node;
+ struct dst_cmd *cmd = st->data;
+ int err;
+
+ cmd->sector = n->size;
+ cmd->rw = st->permissions;
+
+ dst_convert_cmd(cmd);
+
+ dst_state_lock(st);
+ err = dst_data_send_header(st->socket, cmd, sizeof(struct dst_cmd), 0);
+ dst_state_unlock(st);
+
+ return err;
+}
+
+/*
+ * Receive block IO from the network.
+ */
+static int dst_recv_bio(struct dst_state *st, struct bio *bio, unsigned int total_size)
+{
+ struct bio_vec *bv;
+ int i, err;
+ void *data;
+ unsigned int sz;
+
+ bio_for_each_segment(bv, bio, i) {
+ sz = min(total_size, bv->bv_len);
+
+ dprintk("%s: bio: %llu/%u, total: %u, len: %u, sz: %u, off: %u.\n",
+ __func__, (u64)bio->bi_sector, bio->bi_size, total_size,
+ bv->bv_len, sz, bv->bv_offset);
+
+ data = kmap(bv->bv_page) + bv->bv_offset;
+ err = dst_data_recv(st, data, sz);
+ kunmap(bv->bv_page);
+
+ bv->bv_len = sz;
+
+ if (err)
+ return err;
+
+ total_size -= sz;
+ if (total_size == 0)
+ break;
+ }
+
+ return 0;
+}
+
+/*
+ * Our block IO has just completed and arrived: get it.
+ */
+static int dst_process_io_response(struct dst_state *st)
+{
+ struct dst_node *n = st->node;
+ struct dst_cmd *cmd = st->data;
+ struct dst_trans *t;
+ int err = 0;
+ struct bio *bio;
+
+ mutex_lock(&n->trans_lock);
+ t = dst_trans_search(n, cmd->id);
+ mutex_unlock(&n->trans_lock);
+
+ if (!t)
+ goto err_out_exit;
+
+ bio = t->bio;
+
+ dprintk("%s: bio: %llu/%u, cmd_size: %u, csize: %u, dir: %lu.\n",
+ __func__, (u64)bio->bi_sector, bio->bi_size, cmd->size,
+ cmd->csize, bio_data_dir(bio));
+
+ if (bio_data_dir(bio) == READ) {
+ if (bio->bi_size != cmd->size - cmd->csize)
+ goto err_out_exit;
+
+ if (dst_need_crypto(n)) {
+ err = dst_recv_cdata(st, t->cmd.hash);
+ if (err)
+ goto err_out_exit;
+ }
+
+ err = dst_recv_bio(st, t->bio, bio->bi_size);
+ if (err)
+ goto err_out_exit;
+
+ if (dst_need_crypto(n))
+ return dst_trans_crypto(t);
+ } else {
+ err = -EBADMSG;
+ if (cmd->size || cmd->csize)
+ goto err_out_exit;
+ }
+
+ dst_trans_remove(t);
+ dst_trans_put(t);
+
+ return 0;
+
+err_out_exit:
+ return err;
+}
+
+/*
+ * Receive crypto data.
+ */
+int dst_recv_cdata(struct dst_state *st, void *cdata)
+{
+ struct dst_cmd *cmd = st->data;
+ struct dst_node *n = st->node;
+ struct dst_crypto_ctl *c = &n->crypto;
+ int err;
+
+ if (cmd->csize != c->crypto_attached_size) {
+ dprintk("%s: cmd: cmd: %u, sector: %llu, size: %u, "
+ "csize: %u != digest size %u.\n",
+ __func__, cmd->cmd, cmd->sector, cmd->size,
+ cmd->csize, c->crypto_attached_size);
+ err = -EINVAL;
+ goto err_out_exit;
+ }
+
+ err = dst_data_recv(st, cdata, cmd->csize);
+ if (err)
+ goto err_out_exit;
+
+ cmd->size -= cmd->csize;
+ return 0;
+
+err_out_exit:
+ return err;
+}
+
+/*
+ * Receive the command and start its processing.
+ */
+static int dst_recv_processing(struct dst_state *st)
+{
+ int err = -EINTR;
+ struct dst_cmd *cmd = st->data;
+
+ /*
+ * If socket will be reset after this statement, then
+ * dst_data_recv() will just fail and loop will
+ * start again, so it can be done without any locks.
+ *
+ * st->read_socket is needed to prevents state machine
+ * breaking between this data reading and subsequent one
+ * in protocol specific functions during connection reset.
+ * In case of reset we have to read next command and do
+ * not expect data for old command to magically appear in
+ * new connection.
+ */
+ st->read_socket = st->socket;
+ err = dst_data_recv(st, cmd, sizeof(struct dst_cmd));
+ if (err)
+ goto out_exit;
+
+ dst_convert_cmd(cmd);
+
+ dprintk("%s: cmd: %u, size: %u, csize: %u, id: %llu, "
+ "sector: %llu, flags: %llx, rw: %llx.\n",
+ __func__, cmd->cmd, cmd->size,
+ cmd->csize, cmd->id, cmd->sector,
+ cmd->flags, cmd->rw);
+
+ /*
+ * This should catch protocol breakage and random garbage instead of commands.
+ */
+ if (unlikely(cmd->csize > st->size - sizeof(struct dst_cmd))) {
+ err = -EBADMSG;
+ goto out_exit;
+ }
+
+ err = -EPROTO;
+ switch (cmd->cmd) {
+ case DST_IO_RESPONSE:
+ err = dst_process_io_response(st);
+ break;
+ case DST_IO:
+ err = dst_process_io(st);
+ break;
+ case DST_CFG:
+ err = dst_process_cfg(st);
+ break;
+ case DST_PING:
+ err = 0;
+ break;
+ default:
+ break;
+ }
+
+out_exit:
+ return err;
+}
+
+/*
+ * Receiving thread. For the client node we should try to reconnect,
+ * for accepted client we just drop the state and expect it to reconnect.
+ */
+static int dst_recv(void *init_data, void *schedule_data)
+{
+ struct dst_state *st = schedule_data;
+ struct dst_node *n = init_data;
+ int err = 0;
+
+ dprintk("%s: start st: %p, n: %p, scan: %lu, need_exit: %d.\n",
+ __func__, st, n, n->trans_scan_timeout, st->need_exit);
+
+ while (n->trans_scan_timeout && !st->need_exit) {
+ err = dst_recv_processing(st);
+ if (err < 0) {
+ if (!st->ctl.type)
+ break;
+
+ if (!n->trans_scan_timeout || st->need_exit)
+ break;
+
+ dst_state_reset(st);
+ msleep(1000);
+ }
+ }
+
+ st->need_exit = 1;
+ wake_up(&st->thread_wait);
+
+ dprintk("%s: freeing receiving socket st: %p.\n", __func__, st);
+ dst_state_lock(st);
+ dst_state_exit_connected(st);
+ dst_state_unlock(st);
+ dst_state_put(st);
+
+ dprintk("%s: freed receiving socket st: %p.\n", __func__, st);
+
+ return err;
+}
+
+/*
+ * Network state dies here and borns couple of lines below.
+ * This object is the main network state processing engine:
+ * sending, receiving, reconnections, all network related
+ * tasks are handled on behalf of the state.
+ */
+static void dst_state_free(struct dst_state *st)
+{
+ dprintk("%s: st: %p.\n", __func__, st);
+ if (st->cleanup)
+ st->cleanup(st);
+ kfree(st->data);
+ kfree(st);
+}
+
+struct dst_state *dst_state_alloc(struct dst_node *n)
+{
+ struct dst_state *st;
+ int err = -ENOMEM;
+
+ st = kzalloc(sizeof(struct dst_state), GFP_KERNEL);
+ if (!st)
+ goto err_out_exit;
+
+ st->node = n;
+ st->need_exit = 0;
+
+ st->size = PAGE_SIZE;
+ st->data = kmalloc(st->size, GFP_KERNEL);
+ if (!st->data)
+ goto err_out_free;
+
+ spin_lock_init(&st->request_lock);
+ INIT_LIST_HEAD(&st->request_list);
+
+ mutex_init(&st->state_lock);
+ init_waitqueue_head(&st->thread_wait);
+
+ /*
+ * One for processing thread, another one for node itself.
+ */
+ atomic_set(&st->refcnt, 2);
+
+ dprintk("%s: st: %p, n: %p.\n", __func__, st, st->node);
+
+ return st;
+
+err_out_free:
+ kfree(st);
+err_out_exit:
+ return ERR_PTR(err);
+}
+
+int dst_state_schedule_receiver(struct dst_state *st)
+{
+ return thread_pool_schedule_private(st->node->pool, dst_thread_setup,
+ dst_recv, st, MAX_SCHEDULE_TIMEOUT, st->node);
+}
+
+/*
+ * Initialize client's connection to the remote peer: allocate state,
+ * connect and perform block IO autoconfiguration.
+ */
+int dst_node_init_connected(struct dst_node *n, struct dst_network_ctl *r)
+{
+ struct dst_state *st;
+ int err = -ENOMEM;
+
+ st = dst_state_alloc(n);
+ if (IS_ERR(st)) {
+ err = PTR_ERR(st);
+ goto err_out_exit;
+ }
+ memcpy(&st->ctl, r, sizeof(struct dst_network_ctl));
+
+ err = dst_state_init_connected(st);
+ if (err)
+ goto err_out_free_data;
+
+ err = dst_request_remote_config(st);
+ if (err)
+ goto err_out_exit_connected;
+ n->state = st;
+
+ err = dst_state_schedule_receiver(st);
+ if (err)
+ goto err_out_exit_connected;
+
+ return 0;
+
+err_out_exit_connected:
+ dst_state_exit_connected(st);
+err_out_free_data:
+ dst_state_free(st);
+err_out_exit:
+ n->state = NULL;
+ return err;
+}
+
+void dst_state_put(struct dst_state *st)
+{
+ dprintk("%s: st: %p, refcnt: %d.\n",
+ __func__, st, atomic_read(&st->refcnt));
+ if (atomic_dec_and_test(&st->refcnt))
+ dst_state_free(st);
+}
+
+/*
+ * Send block IO to the network one by one using zero-copy ->sendpage().
+ */
+int dst_send_bio(struct dst_state *st, struct dst_cmd *cmd, struct bio *bio)
+{
+ struct bio_vec *bv;
+ struct dst_crypto_ctl *c = &st->node->crypto;
+ int err, i = 0;
+ int flags = MSG_WAITALL;
+
+ err = dst_data_send_header(st->socket, cmd,
+ sizeof(struct dst_cmd) + c->crypto_attached_size, bio->bi_vcnt);
+ if (err)
+ goto err_out_exit;
+
+ bio_for_each_segment(bv, bio, i) {
+ if (i < bio->bi_vcnt - 1)
+ flags |= MSG_MORE;
+
+ err = kernel_sendpage(st->socket, bv->bv_page, bv->bv_offset,
+ bv->bv_len, flags);
+ if (err <= 0)
+ goto err_out_exit;
+ }
+
+ return 0;
+
+err_out_exit:
+ dprintk("%s: %d/%d, flags: %x, err: %d.\n",
+ __func__, i, bio->bi_vcnt, flags, err);
+ return err;
+}
+
+/*
+ * Send transaction to the remote peer.
+ */
+int dst_trans_send(struct dst_trans *t)
+{
+ int err;
+ struct dst_state *st = t->n->state;
+ struct bio *bio = t->bio;
+
+ dst_convert_cmd(&t->cmd);
+
+ dst_state_lock(st);
+ if (!st->socket) {
+ err = dst_state_init_connected(st);
+ if (err)
+ goto err_out_unlock;
+ }
+
+ if (bio_data_dir(bio) == WRITE) {
+ err = dst_send_bio(st, &t->cmd, t->bio);
+ } else {
+ err = dst_data_send_header(st->socket, &t->cmd,
+ sizeof(struct dst_cmd), 0);
+ }
+ if (err)
+ goto err_out_reset;
+
+ dst_state_unlock(st);
+ return 0;
+
+err_out_reset:
+ dst_state_reset_nolock(st);
+err_out_unlock:
+ dst_state_unlock(st);
+
+ return err;
+}