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    Subject[3/7] dst: export node.
    Date
    This patch introduces remote (export) node machinery: initialization
    address/port (and other socket parameters), export block device (can be
    another DST storage for example or local device like /dev/sda1), local
    IO processing engine (BIO state machines, receiving/submitting logic).
    Network management for the export node like accepting new client, scheduling
    its command processing thread, receiving/sending IO requests, all are placed
    here.

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

    diff --git a/drivers/block/dst/export.c b/drivers/block/dst/export.c
    new file mode 100644
    index 0000000..122fe75
    --- /dev/null
    +++ b/drivers/block/dst/export.c
    @@ -0,0 +1,664 @@
    +/*
    + * 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/blkdev.h>
    +#include <linux/bio.h>
    +#include <linux/dst.h>
    +#include <linux/in.h>
    +#include <linux/in6.h>
    +#include <linux/poll.h>
    +#include <linux/slab.h>
    +#include <linux/socket.h>
    +
    +#include <net/sock.h>
    +
    +/*
    + * Export bioset is used for server block IO requests.
    + */
    +static struct bio_set *dst_bio_set;
    +
    +int __init dst_export_init(void)
    +{
    + int err = -ENOMEM;
    +
    + dst_bio_set = bioset_create(32, 32);
    + if (!dst_bio_set)
    + goto err_out_exit;
    +
    + return 0;
    +
    +err_out_exit:
    + return err;
    +}
    +
    +void dst_export_exit(void)
    +{
    + bioset_free(dst_bio_set);
    +}
    +
    +/*
    + * When client connects and autonegotiates with the server node,
    + * its permissions are checked in a security attributes and sent
    + * back.
    + */
    +static unsigned int dst_check_permissions(struct dst_state *main, struct dst_state *st)
    +{
    + struct dst_node *n = main->node;
    + struct dst_secure *sentry;
    + struct dst_secure_user *s;
    + struct saddr *sa = &st->ctl.addr;
    + unsigned int perm = 0;
    +
    + mutex_lock(&n->security_lock);
    + list_for_each_entry(sentry, &n->security_list, sec_entry) {
    + s = &sentry->sec;
    +
    + if (s->addr.sa_family != sa->sa_family)
    + continue;
    +
    + if (s->addr.sa_data_len != sa->sa_data_len)
    + continue;
    +
    + /*
    + * This '2' below is a port field. This may be very wrong to do
    + * in atalk for example though. If there will be any need to extent
    + * protocol to something else, I can create per-family helpers and
    + * use them instead of this memcmp.
    + */
    + if (memcmp(s->addr.sa_data + 2, sa->sa_data + 2,
    + sa->sa_data_len - 2))
    + continue;
    +
    + perm = s->permissions;
    + }
    + mutex_unlock(&n->security_lock);
    +
    + return perm;
    +}
    +
    +/*
    + * Accept new client: allocate appropriate network state and check permissions.
    + */
    +static struct dst_state *dst_accept_client(struct dst_state *st)
    +{
    + 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;
    + struct socket *sock = NULL;
    + struct dst_state *new;
    +
    + while (!err && !sock) {
    + 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;
    +
    + /*
    + * Magic HZ? Polling check above is not safe in
    + * all cases (like socket reset in BH context),
    + * so it is simpler just to postpone it to the
    + * process context instead of implementing special
    + * locking there.
    + */
    + schedule_timeout(HZ);
    + }
    + finish_wait(&st->thread_wait, &wait);
    + }
    +
    + err = -ECONNRESET;
    + dst_state_lock(st);
    +
    + dprintk("%s: st: %p, revents: %x [err: %d, in: %d].\n",
    + __func__, st, revents, revents & err_mask,
    + revents & POLLIN);
    +
    + if (revents & err_mask) {
    + dprintk("%s: revents: %x, socket: %p, err: %d.\n",
    + __func__, revents, st->socket, err);
    + err = -ECONNRESET;
    + }
    +
    + if (!n->trans_scan_timeout || st->need_exit)
    + err = -ENODEV;
    +
    + if (st->socket && (revents & POLLIN))
    + err = kernel_accept(st->socket, &sock, 0);
    +
    + dst_state_unlock(st);
    + }
    +
    + if (err)
    + goto err_out_exit;
    +
    + new = dst_state_alloc(st->node);
    + if (!new) {
    + err = -ENOMEM;
    + goto err_out_release;
    + }
    + new->socket = sock;
    +
    + new->ctl.addr.sa_data_len = sizeof(struct sockaddr);
    + err = kernel_getpeername(sock, (struct sockaddr *)&new->ctl.addr,
    + (int *)&new->ctl.addr.sa_data_len);
    + if (err)
    + goto err_out_put;
    +
    + new->permissions = dst_check_permissions(st, new);
    + if (new->permissions == 0) {
    + err = -EPERM;
    + dst_dump_addr(sock, (struct sockaddr *)&new->ctl.addr,
    + "Client is not allowed to connect");
    + goto err_out_put;
    + }
    +
    + err = dst_poll_init(new);
    + if (err)
    + goto err_out_put;
    +
    + dst_dump_addr(sock, (struct sockaddr *)&new->ctl.addr,
    + "Connected client");
    +
    + return new;
    +
    +err_out_put:
    + dst_state_put(new);
    +err_out_release:
    + sock_release(sock);
    +err_out_exit:
    + return ERR_PTR(err);
    +}
    +
    +/*
    + * Each server's block request sometime finishes.
    + * Usually it happens in hard irq context of the appropriate controller,
    + * so to play good with all cases we just queue BIO into the queue
    + * and wake up processing thread, which gets completed request and
    + * send (encrypting if needed) it back to the client (if it was a read
    + * request), or sends back reply that writing succesfully completed.
    + */
    +static int dst_export_process_request_queue(struct dst_state *st)
    +{
    + unsigned long flags;
    + struct dst_export_priv *p = NULL;
    + struct bio *bio;
    + int err = 0;
    +
    + while (!list_empty(&st->request_list)) {
    + spin_lock_irqsave(&st->request_lock, flags);
    + if (!list_empty(&st->request_list)) {
    + p = list_first_entry(&st->request_list,
    + struct dst_export_priv, request_entry);
    + list_del(&p->request_entry);
    + }
    + spin_unlock_irqrestore(&st->request_lock, flags);
    +
    + if (!p)
    + break;
    +
    + bio = p->bio;
    +
    + if (dst_need_crypto(st->node) && (bio_data_dir(bio) == READ))
    + err = dst_export_crypto(st->node, bio);
    + else
    + err = dst_export_send_bio(bio);
    +
    + if (err)
    + break;
    + }
    +
    + return err;
    +}
    +
    +/*
    + * Cleanup export state.
    + * It has to wait until all requests are finished,
    + * and then free them all.
    + */
    +static void dst_state_cleanup_export(struct dst_state *st)
    +{
    + struct dst_export_priv *p;
    + unsigned long flags;
    +
    + /*
    + * This loop waits for all pending bios to be completed and freed.
    + */
    + while (atomic_read(&st->refcnt) > 1) {
    + dprintk("%s: st: %p, refcnt: %d, list_empty: %d.\n",
    + __func__, st, atomic_read(&st->refcnt),
    + list_empty(&st->request_list));
    + wait_event_timeout(st->thread_wait,
    + (atomic_read(&st->refcnt) == 1) ||
    + !list_empty(&st->request_list),
    + HZ/2);
    +
    + while (!list_empty(&st->request_list)) {
    + p = NULL;
    + spin_lock_irqsave(&st->request_lock, flags);
    + if (!list_empty(&st->request_list)) {
    + p = list_first_entry(&st->request_list,
    + struct dst_export_priv, request_entry);
    + list_del(&p->request_entry);
    + }
    + spin_unlock_irqrestore(&st->request_lock, flags);
    +
    + if (p)
    + bio_put(p->bio);
    +
    + dprintk("%s: st: %p, refcnt: %d, list_empty: %d, p: %p.\n",
    + __func__, st, atomic_read(&st->refcnt),
    + list_empty(&st->request_list), p);
    + }
    + }
    +
    + dst_state_put(st);
    +}
    +
    +/*
    + * Client accepting thread.
    + * Not only accepts new connection, but also schedules receiving thread
    + * and performs request completion described above.
    + */
    +static int dst_accept(void *init_data, void *schedule_data)
    +{
    + struct dst_state *main_st = schedule_data;
    + struct dst_node *n = init_data;
    + struct dst_state *st;
    + int err;
    +
    + while (n->trans_scan_timeout && !main_st->need_exit) {
    + dprintk("%s: main_st: %p, n: %p.\n", __func__, main_st, n);
    + st = dst_accept_client(main_st);
    + if (IS_ERR(st))
    + continue;
    +
    + err = dst_state_schedule_receiver(st);
    + if (!err) {
    + while (n->trans_scan_timeout) {
    + err = wait_event_interruptible_timeout(st->thread_wait,
    + !list_empty(&st->request_list) ||
    + !n->trans_scan_timeout ||
    + st->need_exit,
    + HZ);
    +
    + if (!n->trans_scan_timeout || st->need_exit)
    + break;
    +
    + if (list_empty(&st->request_list))
    + continue;
    +
    + err = dst_export_process_request_queue(st);
    + if (err)
    + break;
    + }
    +
    + st->need_exit = 1;
    + wake_up(&st->thread_wait);
    + }
    +
    + dst_state_cleanup_export(st);
    + }
    +
    + dprintk("%s: freeing listening socket st: %p.\n", __func__, main_st);
    +
    + dst_state_lock(main_st);
    + dst_poll_exit(main_st);
    + dst_state_socket_release(main_st);
    + dst_state_unlock(main_st);
    + dst_state_put(main_st);
    + dprintk("%s: freed listening socket st: %p.\n", __func__, main_st);
    +
    + return 0;
    +}
    +
    +int dst_start_export(struct dst_node *n)
    +{
    + if (list_empty(&n->security_list)) {
    + printk(KERN_ERR "You are trying to export node '%s' without security attributes.\n"
    + "No clients will be allowed to connect. Exiting.\n", n->name);
    + return -EINVAL;
    + }
    + return dst_node_trans_init(n, sizeof(struct dst_export_priv));
    +}
    +
    +/*
    + * Initialize listening state and schedule accepting thread.
    + */
    +int dst_node_init_listened(struct dst_node *n, struct dst_export_ctl *le)
    +{
    + struct dst_state *st;
    + int err = -ENOMEM;
    + struct dst_network_ctl *ctl = &le->ctl;
    +
    + memcpy(&n->info->net, ctl, sizeof(struct dst_network_ctl));
    +
    + st = dst_state_alloc(n);
    + if (IS_ERR(st)) {
    + err = PTR_ERR(st);
    + goto err_out_exit;
    + }
    + memcpy(&st->ctl, ctl, sizeof(struct dst_network_ctl));
    +
    + err = dst_state_socket_create(st);
    + if (err)
    + goto err_out_put;
    +
    + st->socket->sk->sk_reuse = 1;
    +
    + err = kernel_bind(st->socket, (struct sockaddr *)&ctl->addr,
    + ctl->addr.sa_data_len);
    + if (err)
    + goto err_out_socket_release;
    +
    + err = kernel_listen(st->socket, 1024);
    + if (err)
    + goto err_out_socket_release;
    + n->state = st;
    +
    + err = dst_poll_init(st);
    + if (err)
    + goto err_out_socket_release;
    +
    + dst_state_get(st);
    +
    + err = thread_pool_schedule(n->pool, dst_thread_setup,
    + dst_accept, st, MAX_SCHEDULE_TIMEOUT);
    + if (err)
    + goto err_out_poll_exit;
    +
    + return 0;
    +
    +err_out_poll_exit:
    + dst_poll_exit(st);
    +err_out_socket_release:
    + dst_state_socket_release(st);
    +err_out_put:
    + dst_state_put(st);
    +err_out_exit:
    + n->state = NULL;
    + return err;
    +}
    +
    +/*
    + * Free bio and related private data.
    + * Also drop a reference counter for appropriate state,
    + * which waits when there are no more block IOs in-flight.
    + */
    +static void dst_bio_destructor(struct bio *bio)
    +{
    + struct bio_vec *bv;
    + struct dst_export_priv *priv = bio->bi_private;
    + int i;
    +
    + bio_for_each_segment(bv, bio, i) {
    + if (!bv->bv_page)
    + break;
    +
    + __free_page(bv->bv_page);
    + }
    +
    + if (priv) {
    + struct dst_node *n = priv->state->node;
    +
    + dst_state_put(priv->state);
    + mempool_free(priv, n->trans_pool);
    + }
    + bio_free(bio, dst_bio_set);
    +}
    +
    +/*
    + * Block IO completion. Queue request to be sent back to
    + * the client (or just confirmation).
    + */
    +static void dst_bio_end_io(struct bio *bio, int err)
    +{
    + struct dst_export_priv *p = bio->bi_private;
    + struct dst_state *st = p->state;
    + unsigned long flags;
    +
    + spin_lock_irqsave(&st->request_lock, flags);
    + list_add_tail(&p->request_entry, &st->request_list);
    + spin_unlock_irqrestore(&st->request_lock, flags);
    +
    + wake_up(&st->thread_wait);
    +}
    +
    +/*
    + * Allocate read request for the server.
    + */
    +static int dst_export_read_request(struct bio *bio, unsigned int total_size)
    +{
    + unsigned int size;
    + struct page *page;
    + int err;
    +
    + while (total_size) {
    + err = -ENOMEM;
    + page = alloc_page(GFP_KERNEL);
    + if (!page)
    + goto err_out_exit;
    +
    + size = min_t(unsigned int, PAGE_SIZE, total_size);
    +
    + err = bio_add_page(bio, page, size, 0);
    + dprintk("%s: bio: %llu/%u, size: %u, err: %d.\n",
    + __func__, (u64)bio->bi_sector, bio->bi_size,
    + size, err);
    + if (err <= 0)
    + goto err_out_free_page;
    +
    + total_size -= size;
    + }
    +
    + return 0;
    +
    +err_out_free_page:
    + __free_page(page);
    +err_out_exit:
    + return err;
    +}
    +
    +/*
    + * Allocate write request for the server.
    + * Should not only get pages, but also read data from the network.
    + */
    +static int dst_export_write_request(struct dst_state *st,
    + struct bio *bio, unsigned int total_size)
    +{
    + unsigned int size;
    + struct page *page;
    + void *data;
    + int err;
    +
    + while (total_size) {
    + err = -ENOMEM;
    + page = alloc_page(GFP_KERNEL);
    + if (!page)
    + goto err_out_exit;
    +
    + data = kmap(page);
    + if (!data)
    + goto err_out_free_page;
    +
    + size = min_t(unsigned int, PAGE_SIZE, total_size);
    +
    + err = dst_data_recv(st, data, size);
    + if (err)
    + goto err_out_unmap_page;
    +
    + err = bio_add_page(bio, page, size, 0);
    + if (err <= 0)
    + goto err_out_unmap_page;
    +
    + kunmap(page);
    +
    + total_size -= size;
    + }
    +
    + return 0;
    +
    +err_out_unmap_page:
    + kunmap(page);
    +err_out_free_page:
    + __free_page(page);
    +err_out_exit:
    + return err;
    +}
    +
    +/*
    + * Groovy, we've gotten an IO request from the client.
    + * Allocate BIO from the bioset, private data from the mempool
    + * and lots of pages for IO.
    + */
    +int dst_process_io(struct dst_state *st)
    +{
    + struct dst_node *n = st->node;
    + struct dst_cmd *cmd = st->data;
    + struct bio *bio;
    + struct dst_export_priv *priv;
    + int err = -ENOMEM;
    +
    + if (unlikely(!n->bdev)) {
    + err = -EINVAL;
    + goto err_out_exit;
    + }
    +
    + bio = bio_alloc_bioset(GFP_KERNEL,
    + PAGE_ALIGN(cmd->size) >> PAGE_SHIFT,
    + dst_bio_set);
    + if (!bio)
    + goto err_out_exit;
    + bio->bi_private = NULL;
    +
    + priv = mempool_alloc(st->node->trans_pool, GFP_KERNEL);
    + if (!priv)
    + goto err_out_free;
    +
    + priv->state = dst_state_get(st);
    + priv->bio = bio;
    +
    + bio->bi_private = priv;
    + bio->bi_end_io = dst_bio_end_io;
    + bio->bi_destructor = dst_bio_destructor;
    + bio->bi_bdev = n->bdev;
    +
    + /*
    + * Server side is only interested in two low bits:
    + * uptodate (set by itself actually) and rw block
    + */
    + bio->bi_flags |= cmd->flags & 3;
    +
    + bio->bi_rw = cmd->rw;
    + bio->bi_size = 0;
    + bio->bi_sector = cmd->sector;
    +
    + dst_bio_to_cmd(bio, &priv->cmd, DST_IO_RESPONSE, cmd->id);
    +
    + priv->cmd.flags = 0;
    + priv->cmd.size = cmd->size;
    +
    + if (bio_data_dir(bio) == WRITE) {
    + err = dst_recv_cdata(st, priv->cmd.hash);
    + if (err)
    + goto err_out_free;
    +
    + err = dst_export_write_request(st, bio, cmd->size);
    + if (err)
    + goto err_out_free;
    +
    + if (dst_need_crypto(n))
    + return dst_export_crypto(n, bio);
    + } else {
    + err = dst_export_read_request(bio, cmd->size);
    + if (err)
    + goto err_out_free;
    + }
    +
    + dprintk("%s: bio: %llu/%u, rw: %lu, dir: %lu, flags: %lx, phys: %d.\n",
    + __func__, (u64)bio->bi_sector, bio->bi_size,
    + bio->bi_rw, bio_data_dir(bio),
    + bio->bi_flags, bio->bi_phys_segments);
    +
    + generic_make_request(bio);
    +
    + return 0;
    +
    +err_out_free:
    + bio_put(bio);
    +err_out_exit:
    + return err;
    +}
    +
    +/*
    + * Ok, block IO is ready, let's send it back to the client...
    + */
    +int dst_export_send_bio(struct bio *bio)
    +{
    + struct dst_export_priv *p = bio->bi_private;
    + struct dst_state *st = p->state;
    + struct dst_cmd *cmd = &p->cmd;
    + int err;
    +
    + dprintk("%s: id: %llu, bio: %llu/%u, csize: %u, flags: %lu, rw: %lu.\n",
    + __func__, cmd->id, (u64)bio->bi_sector, bio->bi_size,
    + cmd->csize, bio->bi_flags, bio->bi_rw);
    +
    + dst_convert_cmd(cmd);
    +
    + dst_state_lock(st);
    + if (!st->socket) {
    + err = -ECONNRESET;
    + goto err_out_unlock;
    + }
    +
    + if (bio_data_dir(bio) == WRITE) {
    + /* ... or just confirmation that writing has completed. */
    + cmd->size = cmd->csize = 0;
    + err = dst_data_send_header(st->socket, cmd,
    + sizeof(struct dst_cmd), 0);
    + if (err)
    + goto err_out_unlock;
    + } else {
    + err = dst_send_bio(st, cmd, bio);
    + if (err)
    + goto err_out_unlock;
    + }
    +
    + dst_state_unlock(st);
    +
    + bio_put(bio);
    + return 0;
    +
    +err_out_unlock:
    + dst_state_unlock(st);
    +
    + bio_put(bio);
    + return err;
    +}

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