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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
    drbd.c
 
    This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
 
    Copyright (C) 2001-2008, LINBIT Information Technologies GmbH.
    Copyright (C) 1999-2008, Philipp Reisner <philipp.reisner@linbit.com>.
    Copyright (C) 2002-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
 
    Thanks to Carter Burden, Bart Grantham and Gennadiy Nerubayev
    from Logicworks, Inc. for making SDP replication support possible.
 
 
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/module.h>
 #include <linux/jiffies.h>
 #include <linux/drbd.h>
 #include <linux/uaccess.h>
 #include <asm/types.h>
 #include <net/sock.h>
 #include <linux/ctype.h>
 #include <linux/mutex.h>
 #include <linux/fs.h>
 #include <linux/file.h>
 #include <linux/proc_fs.h>
 #include <linux/init.h>
 #include <linux/mm.h>
 #include <linux/memcontrol.h>
 #include <linux/mm_inline.h>
 #include <linux/slab.h>
 #include <linux/random.h>
 #include <linux/reboot.h>
 #include <linux/notifier.h>
 #include <linux/kthread.h>
 #include <linux/workqueue.h>
 #define __KERNEL_SYSCALLS__
 #include <linux/unistd.h>
 #include <linux/vmalloc.h>
 #include <linux/sched/signal.h>
 
 #include <linux/drbd_limits.h>
 #include "drbd_int.h"
 #include "drbd_protocol.h"
 #include "drbd_req.h" /* only for _req_mod in tl_release and tl_clear */
 #include "drbd_vli.h"
 #include "drbd_debugfs.h"
 
 static DEFINE_MUTEX(drbd_main_mutex);
 static int drbd_open(struct block_device *bdev, fmode_t mode);
 static void drbd_release(struct gendisk *gd, fmode_t mode);
 static void md_sync_timer_fn(struct timer_list *t);
 static int w_bitmap_io(struct drbd_work *w, int unused);
 
 MODULE_AUTHOR("Philipp Reisner <phil@linbit.com>, "
           "Lars Ellenberg <lars@linbit.com>");
 MODULE_DESCRIPTION("drbd - Distributed Replicated Block Device v" REL_VERSION);
 MODULE_VERSION(REL_VERSION);
 MODULE_LICENSE("GPL");
 MODULE_PARM_DESC(minor_count, "Approximate number of drbd devices ("
          __stringify(DRBD_MINOR_COUNT_MIN) "-" __stringify(DRBD_MINOR_COUNT_MAX) ")");
 MODULE_ALIAS_BLOCKDEV_MAJOR(DRBD_MAJOR);
 
 #include <linux/moduleparam.h>
 /* thanks to these macros, if compiled into the kernel (not-module),
  * these become boot parameters (e.g., drbd.minor_count) */
 
 #ifdef CONFIG_DRBD_FAULT_INJECTION
 int drbd_enable_faults;
 int drbd_fault_rate;
 static int drbd_fault_count;
 static int drbd_fault_devs;
 /* bitmap of enabled faults */
 module_param_named(enable_faults, drbd_enable_faults, int, 0664);
 /* fault rate % value - applies to all enabled faults */
 module_param_named(fault_rate, drbd_fault_rate, int, 0664);
 /* count of faults inserted */
 module_param_named(fault_count, drbd_fault_count, int, 0664);
 /* bitmap of devices to insert faults on */
 module_param_named(fault_devs, drbd_fault_devs, int, 0644);
 #endif
 
 /* module parameters we can keep static */
 static bool drbd_allow_oos; /* allow_open_on_secondary */
 static bool drbd_disable_sendpage;
 MODULE_PARM_DESC(allow_oos, "DONT USE!");
 module_param_named(allow_oos, drbd_allow_oos, bool, 0);
 module_param_named(disable_sendpage, drbd_disable_sendpage, bool, 0644);
 
 /* module parameters we share */
 int drbd_proc_details; /* Detail level in proc drbd*/
 module_param_named(proc_details, drbd_proc_details, int, 0644);
 /* module parameters shared with defaults */
 unsigned int drbd_minor_count = DRBD_MINOR_COUNT_DEF;
 /* Module parameter for setting the user mode helper program
  * to run. Default is /sbin/drbdadm */
 char drbd_usermode_helper[80] = "/sbin/drbdadm";
 module_param_named(minor_count, drbd_minor_count, uint, 0444);
 module_param_string(usermode_helper, drbd_usermode_helper, sizeof(drbd_usermode_helper), 0644);
 
 /* in 2.6.x, our device mapping and config info contains our virtual gendisks
  * as member "struct gendisk *vdisk;"
  */
 struct idr drbd_devices;
 struct list_head drbd_resources;
 struct mutex resources_mutex;
 
 struct kmem_cache *drbd_request_cache;
 struct kmem_cache *drbd_ee_cache;   /* peer requests */
 struct kmem_cache *drbd_bm_ext_cache;   /* bitmap extents */
 struct kmem_cache *drbd_al_ext_cache;   /* activity log extents */
 mempool_t drbd_request_mempool;
 mempool_t drbd_ee_mempool;
 mempool_t drbd_md_io_page_pool;
 struct bio_set drbd_md_io_bio_set;
 struct bio_set drbd_io_bio_set;
 
 /* I do not use a standard mempool, because:
    1) I want to hand out the pre-allocated objects first.
    2) I want to be able to interrupt sleeping allocation with a signal.
    Note: This is a single linked list, the next pointer is the private
      member of struct page.
  */
 struct page *drbd_pp_pool;
 DEFINE_SPINLOCK(drbd_pp_lock);
 int          drbd_pp_vacant;
 wait_queue_head_t drbd_pp_wait;
 
 DEFINE_RATELIMIT_STATE(drbd_ratelimit_state, 5 * HZ, 5);
 
 static const struct block_device_operations drbd_ops = {
     .owner      = THIS_MODULE,
     .submit_bio = drbd_submit_bio,
     .open       = drbd_open,
     .release    = drbd_release,
 };
 
 #ifdef __CHECKER__
 /* When checking with sparse, and this is an inline function, sparse will
    give tons of false positives. When this is a real functions sparse works.
  */
 int _get_ldev_if_state(struct drbd_device *device, enum drbd_disk_state mins)
 {
     int io_allowed;
 
     atomic_inc(&device->local_cnt);
     io_allowed = (device->state.disk >= mins);
     if (!io_allowed) {
         if (atomic_dec_and_test(&device->local_cnt))
             wake_up(&device->misc_wait);
     }
     return io_allowed;
 }
 
 #endif
 
 /**
  * tl_release() - mark as BARRIER_ACKED all requests in the corresponding transfer log epoch
  * @connection: DRBD connection.
  * @barrier_nr: Expected identifier of the DRBD write barrier packet.
  * @set_size:   Expected number of requests before that barrier.
  *
  * In case the passed barrier_nr or set_size does not match the oldest
  * epoch of not yet barrier-acked requests, this function will cause a
  * termination of the connection.
  */
 void tl_release(struct drbd_connection *connection, unsigned int barrier_nr,
         unsigned int set_size)
 {
     struct drbd_request *r;
     struct drbd_request *req = NULL, *tmp = NULL;
     int expect_epoch = 0;
     int expect_size = 0;
 
     spin_lock_irq(&connection->resource->req_lock);
 
     /* find oldest not yet barrier-acked write request,
      * count writes in its epoch. */
     list_for_each_entry(r, &connection->transfer_log, tl_requests) {
         const unsigned s = r->rq_state;
         if (!req) {
             if (!(s & RQ_WRITE))
                 continue;
             if (!(s & RQ_NET_MASK))
                 continue;
             if (s & RQ_NET_DONE)
                 continue;
             req = r;
             expect_epoch = req->epoch;
             expect_size ++;
         } else {
             if (r->epoch != expect_epoch)
                 break;
             if (!(s & RQ_WRITE))
                 continue;
             /* if (s & RQ_DONE): not expected */
             /* if (!(s & RQ_NET_MASK)): not expected */
             expect_size++;
         }
     }
 
     /* first some paranoia code */
     if (req == NULL) {
         drbd_err(connection, "BAD! BarrierAck #%u received, but no epoch in tl!?\n",
              barrier_nr);
         goto bail;
     }
     if (expect_epoch != barrier_nr) {
         drbd_err(connection, "BAD! BarrierAck #%u received, expected #%u!\n",
              barrier_nr, expect_epoch);
         goto bail;
     }
 
     if (expect_size != set_size) {
         drbd_err(connection, "BAD! BarrierAck #%u received with n_writes=%u, expected n_writes=%u!\n",
              barrier_nr, set_size, expect_size);
         goto bail;
     }
 
     /* Clean up list of requests processed during current epoch. */
     /* this extra list walk restart is paranoia,
      * to catch requests being barrier-acked "unexpectedly".
      * It usually should find the same req again, or some READ preceding it. */
     list_for_each_entry(req, &connection->transfer_log, tl_requests)
         if (req->epoch == expect_epoch) {
             tmp = req;
             break;
         }
     req = list_prepare_entry(tmp, &connection->transfer_log, tl_requests);
     list_for_each_entry_safe_from(req, r, &connection->transfer_log, tl_requests) {
         if (req->epoch != expect_epoch)
             break;
         _req_mod(req, BARRIER_ACKED);
     }
     spin_unlock_irq(&connection->resource->req_lock);
 
     return;
 
 bail:
     spin_unlock_irq(&connection->resource->req_lock);
     conn_request_state(connection, NS(conn, C_PROTOCOL_ERROR), CS_HARD);
 }
 
 
 /**
  * _tl_restart() - Walks the transfer log, and applies an action to all requests
  * @connection: DRBD connection to operate on.
  * @what:       The action/event to perform with all request objects
  *
  * @what might be one of CONNECTION_LOST_WHILE_PENDING, RESEND, FAIL_FROZEN_DISK_IO,
  * RESTART_FROZEN_DISK_IO.
  */
 /* must hold resource->req_lock */
 void _tl_restart(struct drbd_connection *connection, enum drbd_req_event what)
 {
     struct drbd_request *req, *r;
 
     list_for_each_entry_safe(req, r, &connection->transfer_log, tl_requests)
         _req_mod(req, what);
 }
 
 void tl_restart(struct drbd_connection *connection, enum drbd_req_event what)
 {
     spin_lock_irq(&connection->resource->req_lock);
     _tl_restart(connection, what);
     spin_unlock_irq(&connection->resource->req_lock);
 }
 
 /**
  * tl_clear() - Clears all requests and &struct drbd_tl_epoch objects out of the TL
  * @connection: DRBD connection.
  *
  * This is called after the connection to the peer was lost. The storage covered
  * by the requests on the transfer gets marked as our of sync. Called from the
  * receiver thread and the worker thread.
  */
 void tl_clear(struct drbd_connection *connection)
 {
     tl_restart(connection, CONNECTION_LOST_WHILE_PENDING);
 }
 
 /**
  * tl_abort_disk_io() - Abort disk I/O for all requests for a certain device in the TL
  * @device: DRBD device.
  */
 void tl_abort_disk_io(struct drbd_device *device)
 {
     struct drbd_connection *connection = first_peer_device(device)->connection;
     struct drbd_request *req, *r;
 
     spin_lock_irq(&connection->resource->req_lock);
     list_for_each_entry_safe(req, r, &connection->transfer_log, tl_requests) {
         if (!(req->rq_state & RQ_LOCAL_PENDING))
             continue;
         if (req->device != device)
             continue;
         _req_mod(req, ABORT_DISK_IO);
     }
     spin_unlock_irq(&connection->resource->req_lock);
 }
 
 static int drbd_thread_setup(void *arg)
 {
     struct drbd_thread *thi = (struct drbd_thread *) arg;
     struct drbd_resource *resource = thi->resource;
     unsigned long flags;
     int retval;
 
     snprintf(current->comm, sizeof(current->comm), "drbd_%c_%s",
          thi->name[0],
          resource->name);
 
     allow_kernel_signal(DRBD_SIGKILL);
     allow_kernel_signal(SIGXCPU);
 restart:
     retval = thi->function(thi);
 
     spin_lock_irqsave(&thi->t_lock, flags);
 
     /* if the receiver has been "EXITING", the last thing it did
      * was set the conn state to "StandAlone",
      * if now a re-connect request comes in, conn state goes C_UNCONNECTED,
      * and receiver thread will be "started".
      * drbd_thread_start needs to set "RESTARTING" in that case.
      * t_state check and assignment needs to be within the same spinlock,
      * so either thread_start sees EXITING, and can remap to RESTARTING,
      * or thread_start see NONE, and can proceed as normal.
      */
 
     if (thi->t_state == RESTARTING) {
         drbd_info(resource, "Restarting %s thread\n", thi->name);
         thi->t_state = RUNNING;
         spin_unlock_irqrestore(&thi->t_lock, flags);
         goto restart;
     }
 
     thi->task = NULL;
     thi->t_state = NONE;
     smp_mb();
     complete_all(&thi->stop);
     spin_unlock_irqrestore(&thi->t_lock, flags);
 
     drbd_info(resource, "Terminating %s\n", current->comm);
 
     /* Release mod reference taken when thread was started */
 
     if (thi->connection)
         kref_put(&thi->connection->kref, drbd_destroy_connection);
     kref_put(&resource->kref, drbd_destroy_resource);
     module_put(THIS_MODULE);
     return retval;
 }
 
 static void drbd_thread_init(struct drbd_resource *resource, struct drbd_thread *thi,
                  int (*func) (struct drbd_thread *), const char *name)
 {
     spin_lock_init(&thi->t_lock);
     thi->task    = NULL;
     thi->t_state = NONE;
     thi->function = func;
     thi->resource = resource;
     thi->connection = NULL;
     thi->name = name;
 }
 
 int drbd_thread_start(struct drbd_thread *thi)
 {
     struct drbd_resource *resource = thi->resource;
     struct task_struct *nt;
     unsigned long flags;
 
     /* is used from state engine doing drbd_thread_stop_nowait,
      * while holding the req lock irqsave */
     spin_lock_irqsave(&thi->t_lock, flags);
 
     switch (thi->t_state) {
     case NONE:
         drbd_info(resource, "Starting %s thread (from %s [%d])\n",
              thi->name, current->comm, current->pid);
 
         /* Get ref on module for thread - this is released when thread exits */
         if (!try_module_get(THIS_MODULE)) {
             drbd_err(resource, "Failed to get module reference in drbd_thread_start\n");
             spin_unlock_irqrestore(&thi->t_lock, flags);
             return false;
         }
 
         kref_get(&resource->kref);
         if (thi->connection)
             kref_get(&thi->connection->kref);
 
         init_completion(&thi->stop);
         thi->reset_cpu_mask = 1;
         thi->t_state = RUNNING;
         spin_unlock_irqrestore(&thi->t_lock, flags);
         flush_signals(current); /* otherw. may get -ERESTARTNOINTR */
 
         nt = kthread_create(drbd_thread_setup, (void *) thi,
                     "drbd_%c_%s", thi->name[0], thi->resource->name);
 
         if (IS_ERR(nt)) {
             drbd_err(resource, "Couldn't start thread\n");
 
             if (thi->connection)
                 kref_put(&thi->connection->kref, drbd_destroy_connection);
             kref_put(&resource->kref, drbd_destroy_resource);
             module_put(THIS_MODULE);
             return false;
         }
         spin_lock_irqsave(&thi->t_lock, flags);
         thi->task = nt;
         thi->t_state = RUNNING;
         spin_unlock_irqrestore(&thi->t_lock, flags);
         wake_up_process(nt);
         break;
     case EXITING:
         thi->t_state = RESTARTING;
         drbd_info(resource, "Restarting %s thread (from %s [%d])\n",
                 thi->name, current->comm, current->pid);
         fallthrough;
     case RUNNING:
     case RESTARTING:
     default:
         spin_unlock_irqrestore(&thi->t_lock, flags);
         break;
     }
 
     return true;
 }
 
 
 void _drbd_thread_stop(struct drbd_thread *thi, int restart, int wait)
 {
     unsigned long flags;
 
     enum drbd_thread_state ns = restart ? RESTARTING : EXITING;
 
     /* may be called from state engine, holding the req lock irqsave */
     spin_lock_irqsave(&thi->t_lock, flags);
 
     if (thi->t_state == NONE) {
         spin_unlock_irqrestore(&thi->t_lock, flags);
         if (restart)
             drbd_thread_start(thi);
         return;
     }
 
     if (thi->t_state != ns) {
         if (thi->task == NULL) {
             spin_unlock_irqrestore(&thi->t_lock, flags);
             return;
         }
 
         thi->t_state = ns;
         smp_mb();
         init_completion(&thi->stop);
         if (thi->task != current)
             send_sig(DRBD_SIGKILL, thi->task, 1);
     }
 
     spin_unlock_irqrestore(&thi->t_lock, flags);
 
     if (wait)
         wait_for_completion(&thi->stop);
 }
 
 int conn_lowest_minor(struct drbd_connection *connection)
 {
     struct drbd_peer_device *peer_device;
     int vnr = 0, minor = -1;
 
     rcu_read_lock();
     peer_device = idr_get_next(&connection->peer_devices, &vnr);
     if (peer_device)
         minor = device_to_minor(peer_device->device);
     rcu_read_unlock();
 
     return minor;
 }
 
 #ifdef CONFIG_SMP
 /*
  * drbd_calc_cpu_mask() - Generate CPU masks, spread over all CPUs
  *
  * Forces all threads of a resource onto the same CPU. This is beneficial for
  * DRBD's performance. May be overwritten by user's configuration.
  */
 static void drbd_calc_cpu_mask(cpumask_var_t *cpu_mask)
 {
     unsigned int *resources_per_cpu, min_index = ~0;
 
     resources_per_cpu = kcalloc(nr_cpu_ids, sizeof(*resources_per_cpu),
                     GFP_KERNEL);
     if (resources_per_cpu) {
         struct drbd_resource *resource;
         unsigned int cpu, min = ~0;
 
         rcu_read_lock();
         for_each_resource_rcu(resource, &drbd_resources) {
             for_each_cpu(cpu, resource->cpu_mask)
                 resources_per_cpu[cpu]++;
         }
         rcu_read_unlock();
         for_each_online_cpu(cpu) {
             if (resources_per_cpu[cpu] < min) {
                 min = resources_per_cpu[cpu];
                 min_index = cpu;
             }
         }
         kfree(resources_per_cpu);
     }
     if (min_index == ~0) {
         cpumask_setall(*cpu_mask);
         return;
     }
     cpumask_set_cpu(min_index, *cpu_mask);
 }
 
 /**
  * drbd_thread_current_set_cpu() - modifies the cpu mask of the _current_ thread
  * @thi:    drbd_thread object
  *
  * call in the "main loop" of _all_ threads, no need for any mutex, current won't die
  * prematurely.
  */
 void drbd_thread_current_set_cpu(struct drbd_thread *thi)
 {
     struct drbd_resource *resource = thi->resource;
     struct task_struct *p = current;
 
     if (!thi->reset_cpu_mask)
         return;
     thi->reset_cpu_mask = 0;
     set_cpus_allowed_ptr(p, resource->cpu_mask);
 }
 #else
 #define drbd_calc_cpu_mask(A) ({})
 #endif
 
 /*
  * drbd_header_size  -  size of a packet header
  *
  * The header size is a multiple of 8, so any payload following the header is
  * word aligned on 64-bit architectures.  (The bitmap send and receive code
  * relies on this.)
  */
 unsigned int drbd_header_size(struct drbd_connection *connection)
 {
     if (connection->agreed_pro_version >= 100) {
         BUILD_BUG_ON(!IS_ALIGNED(sizeof(struct p_header100), 8));
         return sizeof(struct p_header100);
     } else {
         BUILD_BUG_ON(sizeof(struct p_header80) !=
                  sizeof(struct p_header95));
         BUILD_BUG_ON(!IS_ALIGNED(sizeof(struct p_header80), 8));
         return sizeof(struct p_header80);
     }
 }
 
 static unsigned int prepare_header80(struct p_header80 *h, enum drbd_packet cmd, int size)
 {
     h->magic   = cpu_to_be32(DRBD_MAGIC);
     h->command = cpu_to_be16(cmd);
     h->length  = cpu_to_be16(size);
     return sizeof(struct p_header80);
 }
 
 static unsigned int prepare_header95(struct p_header95 *h, enum drbd_packet cmd, int size)
 {
     h->magic   = cpu_to_be16(DRBD_MAGIC_BIG);
     h->command = cpu_to_be16(cmd);
     h->length = cpu_to_be32(size);
     return sizeof(struct p_header95);
 }
 
 static unsigned int prepare_header100(struct p_header100 *h, enum drbd_packet cmd,
                       int size, int vnr)
 {
     h->magic = cpu_to_be32(DRBD_MAGIC_100);
     h->volume = cpu_to_be16(vnr);
     h->command = cpu_to_be16(cmd);
     h->length = cpu_to_be32(size);
     h->pad = 0;
     return sizeof(struct p_header100);
 }
 
 static unsigned int prepare_header(struct drbd_connection *connection, int vnr,
                    void *buffer, enum drbd_packet cmd, int size)
 {
     if (connection->agreed_pro_version >= 100)
         return prepare_header100(buffer, cmd, size, vnr);
     else if (connection->agreed_pro_version >= 95 &&
          size > DRBD_MAX_SIZE_H80_PACKET)
         return prepare_header95(buffer, cmd, size);
     else
         return prepare_header80(buffer, cmd, size);
 }
 
 static void *__conn_prepare_command(struct drbd_connection *connection,
                     struct drbd_socket *sock)
 {
     if (!sock->socket)
         return NULL;
     return sock->sbuf + drbd_header_size(connection);
 }
 
 void *conn_prepare_command(struct drbd_connection *connection, struct drbd_socket *sock)
 {
     void *p;
 
     mutex_lock(&sock->mutex);
     p = __conn_prepare_command(connection, sock);
     if (!p)
         mutex_unlock(&sock->mutex);
 
     return p;
 }
 
 void *drbd_prepare_command(struct drbd_peer_device *peer_device, struct drbd_socket *sock)
 {
     return conn_prepare_command(peer_device->connection, sock);
 }
 
 static int __send_command(struct drbd_connection *connection, int vnr,
               struct drbd_socket *sock, enum drbd_packet cmd,
               unsigned int header_size, void *data,
               unsigned int size)
 {
     int msg_flags;
     int err;
 
     /*
      * Called with @data == NULL and the size of the data blocks in @size
      * for commands that send data blocks.  For those commands, omit the
      * MSG_MORE flag: this will increase the likelihood that data blocks
      * which are page aligned on the sender will end up page aligned on the
      * receiver.
      */
     msg_flags = data ? MSG_MORE : 0;
 
     header_size += prepare_header(connection, vnr, sock->sbuf, cmd,
                       header_size + size);
     err = drbd_send_all(connection, sock->socket, sock->sbuf, header_size,
                 msg_flags);
     if (data && !err)
         err = drbd_send_all(connection, sock->socket, data, size, 0);
     /* DRBD protocol "pings" are latency critical.
      * This is supposed to trigger tcp_push_pending_frames() */
     if (!err && (cmd == P_PING || cmd == P_PING_ACK))
         tcp_sock_set_nodelay(sock->socket->sk);
 
     return err;
 }
 
 static int __conn_send_command(struct drbd_connection *connection, struct drbd_socket *sock,
                    enum drbd_packet cmd, unsigned int header_size,
                    void *data, unsigned int size)
 {
     return __send_command(connection, 0, sock, cmd, header_size, data, size);
 }
 
 int conn_send_command(struct drbd_connection *connection, struct drbd_socket *sock,
               enum drbd_packet cmd, unsigned int header_size,
               void *data, unsigned int size)
 {
     int err;
 
     err = __conn_send_command(connection, sock, cmd, header_size, data, size);
     mutex_unlock(&sock->mutex);
     return err;
 }
 
 int drbd_send_command(struct drbd_peer_device *peer_device, struct drbd_socket *sock,
               enum drbd_packet cmd, unsigned int header_size,
               void *data, unsigned int size)
 {
     int err;
 
     err = __send_command(peer_device->connection, peer_device->device->vnr,
                  sock, cmd, header_size, data, size);
     mutex_unlock(&sock->mutex);
     return err;
 }
 
 int drbd_send_ping(struct drbd_connection *connection)
 {
     struct drbd_socket *sock;
 
     sock = &connection->meta;
     if (!conn_prepare_command(connection, sock))
         return -EIO;
     return conn_send_command(connection, sock, P_PING, 0, NULL, 0);
 }
 
 int drbd_send_ping_ack(struct drbd_connection *connection)
 {
     struct drbd_socket *sock;
 
     sock = &connection->meta;
     if (!conn_prepare_command(connection, sock))
         return -EIO;
     return conn_send_command(connection, sock, P_PING_ACK, 0, NULL, 0);
 }
 
 int drbd_send_sync_param(struct drbd_peer_device *peer_device)
 {
     struct drbd_socket *sock;
     struct p_rs_param_95 *p;
     int size;
     const int apv = peer_device->connection->agreed_pro_version;
     enum drbd_packet cmd;
     struct net_conf *nc;
     struct disk_conf *dc;
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     if (!p)
         return -EIO;
 
     rcu_read_lock();
     nc = rcu_dereference(peer_device->connection->net_conf);
 
     size = apv <= 87 ? sizeof(struct p_rs_param)
         : apv == 88 ? sizeof(struct p_rs_param)
             + strlen(nc->verify_alg) + 1
         : apv <= 94 ? sizeof(struct p_rs_param_89)
         : /* apv >= 95 */ sizeof(struct p_rs_param_95);
 
     cmd = apv >= 89 ? P_SYNC_PARAM89 : P_SYNC_PARAM;
 
     /* initialize verify_alg and csums_alg */
     BUILD_BUG_ON(sizeof(p->algs) != 2 * SHARED_SECRET_MAX);
     memset(&p->algs, 0, sizeof(p->algs));
 
     if (get_ldev(peer_device->device)) {
         dc = rcu_dereference(peer_device->device->ldev->disk_conf);
         p->resync_rate = cpu_to_be32(dc->resync_rate);
         p->c_plan_ahead = cpu_to_be32(dc->c_plan_ahead);
         p->c_delay_target = cpu_to_be32(dc->c_delay_target);
         p->c_fill_target = cpu_to_be32(dc->c_fill_target);
         p->c_max_rate = cpu_to_be32(dc->c_max_rate);
         put_ldev(peer_device->device);
     } else {
         p->resync_rate = cpu_to_be32(DRBD_RESYNC_RATE_DEF);
         p->c_plan_ahead = cpu_to_be32(DRBD_C_PLAN_AHEAD_DEF);
         p->c_delay_target = cpu_to_be32(DRBD_C_DELAY_TARGET_DEF);
         p->c_fill_target = cpu_to_be32(DRBD_C_FILL_TARGET_DEF);
         p->c_max_rate = cpu_to_be32(DRBD_C_MAX_RATE_DEF);
     }
 
     if (apv >= 88)
         strcpy(p->verify_alg, nc->verify_alg);
     if (apv >= 89)
         strcpy(p->csums_alg, nc->csums_alg);
     rcu_read_unlock();
 
     return drbd_send_command(peer_device, sock, cmd, size, NULL, 0);
 }
 
 int __drbd_send_protocol(struct drbd_connection *connection, enum drbd_packet cmd)
 {
     struct drbd_socket *sock;
     struct p_protocol *p;
     struct net_conf *nc;
     int size, cf;
 
     sock = &connection->data;
     p = __conn_prepare_command(connection, sock);
     if (!p)
         return -EIO;
 
     rcu_read_lock();
     nc = rcu_dereference(connection->net_conf);
 
     if (nc->tentative && connection->agreed_pro_version < 92) {
         rcu_read_unlock();
         drbd_err(connection, "--dry-run is not supported by peer");
         return -EOPNOTSUPP;
     }
 
     size = sizeof(*p);
     if (connection->agreed_pro_version >= 87)
         size += strlen(nc->integrity_alg) + 1;
 
     p->protocol      = cpu_to_be32(nc->wire_protocol);
     p->after_sb_0p   = cpu_to_be32(nc->after_sb_0p);
     p->after_sb_1p   = cpu_to_be32(nc->after_sb_1p);
     p->after_sb_2p   = cpu_to_be32(nc->after_sb_2p);
     p->two_primaries = cpu_to_be32(nc->two_primaries);
     cf = 0;
     if (nc->discard_my_data)
         cf |= CF_DISCARD_MY_DATA;
     if (nc->tentative)
         cf |= CF_DRY_RUN;
     p->conn_flags    = cpu_to_be32(cf);
 
     if (connection->agreed_pro_version >= 87)
         strcpy(p->integrity_alg, nc->integrity_alg);
     rcu_read_unlock();
 
     return __conn_send_command(connection, sock, cmd, size, NULL, 0);
 }
 
 int drbd_send_protocol(struct drbd_connection *connection)
 {
     int err;
 
     mutex_lock(&connection->data.mutex);
     err = __drbd_send_protocol(connection, P_PROTOCOL);
     mutex_unlock(&connection->data.mutex);
 
     return err;
 }
 
 static int _drbd_send_uuids(struct drbd_peer_device *peer_device, u64 uuid_flags)
 {
     struct drbd_device *device = peer_device->device;
     struct drbd_socket *sock;
     struct p_uuids *p;
     int i;
 
     if (!get_ldev_if_state(device, D_NEGOTIATING))
         return 0;
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     if (!p) {
         put_ldev(device);
         return -EIO;
     }
     spin_lock_irq(&device->ldev->md.uuid_lock);
     for (i = UI_CURRENT; i < UI_SIZE; i++)
         p->uuid[i] = cpu_to_be64(device->ldev->md.uuid[i]);
     spin_unlock_irq(&device->ldev->md.uuid_lock);
 
     device->comm_bm_set = drbd_bm_total_weight(device);
     p->uuid[UI_SIZE] = cpu_to_be64(device->comm_bm_set);
     rcu_read_lock();
     uuid_flags |= rcu_dereference(peer_device->connection->net_conf)->discard_my_data ? 1 : 0;
     rcu_read_unlock();
     uuid_flags |= test_bit(CRASHED_PRIMARY, &device->flags) ? 2 : 0;
     uuid_flags |= device->new_state_tmp.disk == D_INCONSISTENT ? 4 : 0;
     p->uuid[UI_FLAGS] = cpu_to_be64(uuid_flags);
 
     put_ldev(device);
     return drbd_send_command(peer_device, sock, P_UUIDS, sizeof(*p), NULL, 0);
 }
 
 int drbd_send_uuids(struct drbd_peer_device *peer_device)
 {
     return _drbd_send_uuids(peer_device, 0);
 }
 
 int drbd_send_uuids_skip_initial_sync(struct drbd_peer_device *peer_device)
 {
     return _drbd_send_uuids(peer_device, 8);
 }
 
 void drbd_print_uuids(struct drbd_device *device, const char *text)
 {
     if (get_ldev_if_state(device, D_NEGOTIATING)) {
         u64 *uuid = device->ldev->md.uuid;
         drbd_info(device, "%s %016llX:%016llX:%016llX:%016llX\n",
              text,
              (unsigned long long)uuid[UI_CURRENT],
              (unsigned long long)uuid[UI_BITMAP],
              (unsigned long long)uuid[UI_HISTORY_START],
              (unsigned long long)uuid[UI_HISTORY_END]);
         put_ldev(device);
     } else {
         drbd_info(device, "%s effective data uuid: %016llX\n",
                 text,
                 (unsigned long long)device->ed_uuid);
     }
 }
 
 void drbd_gen_and_send_sync_uuid(struct drbd_peer_device *peer_device)
 {
     struct drbd_device *device = peer_device->device;
     struct drbd_socket *sock;
     struct p_rs_uuid *p;
     u64 uuid;
 
     D_ASSERT(device, device->state.disk == D_UP_TO_DATE);
 
     uuid = device->ldev->md.uuid[UI_BITMAP];
     if (uuid && uuid != UUID_JUST_CREATED)
         uuid = uuid + UUID_NEW_BM_OFFSET;
     else
         get_random_bytes(&uuid, sizeof(u64));
     drbd_uuid_set(device, UI_BITMAP, uuid);
     drbd_print_uuids(device, "updated sync UUID");
     drbd_md_sync(device);
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     if (p) {
         p->uuid = cpu_to_be64(uuid);
         drbd_send_command(peer_device, sock, P_SYNC_UUID, sizeof(*p), NULL, 0);
     }
 }
 
 int drbd_send_sizes(struct drbd_peer_device *peer_device, int trigger_reply, enum dds_flags flags)
 {
     struct drbd_device *device = peer_device->device;
     struct drbd_socket *sock;
     struct p_sizes *p;
     sector_t d_size, u_size;
     int q_order_type;
     unsigned int max_bio_size;
     unsigned int packet_size;
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     if (!p)
         return -EIO;
 
     packet_size = sizeof(*p);
     if (peer_device->connection->agreed_features & DRBD_FF_WSAME)
         packet_size += sizeof(p->qlim[0]);
 
     memset(p, 0, packet_size);
     if (get_ldev_if_state(device, D_NEGOTIATING)) {
         struct block_device *bdev = device->ldev->backing_bdev;
         struct request_queue *q = bdev_get_queue(bdev);
 
         d_size = drbd_get_max_capacity(device->ldev);
         rcu_read_lock();
         u_size = rcu_dereference(device->ldev->disk_conf)->disk_size;
         rcu_read_unlock();
         q_order_type = drbd_queue_order_type(device);
         max_bio_size = queue_max_hw_sectors(q) << 9;
         max_bio_size = min(max_bio_size, DRBD_MAX_BIO_SIZE);
         p->qlim->physical_block_size =
             cpu_to_be32(bdev_physical_block_size(bdev));
         p->qlim->logical_block_size =
             cpu_to_be32(bdev_logical_block_size(bdev));
         p->qlim->alignment_offset =
             cpu_to_be32(bdev_alignment_offset(bdev));
         p->qlim->io_min = cpu_to_be32(bdev_io_min(bdev));
         p->qlim->io_opt = cpu_to_be32(bdev_io_opt(bdev));
         p->qlim->discard_enabled = !!bdev_max_discard_sectors(bdev);
         put_ldev(device);
     } else {
         struct request_queue *q = device->rq_queue;
 
         p->qlim->physical_block_size =
             cpu_to_be32(queue_physical_block_size(q));
         p->qlim->logical_block_size =
             cpu_to_be32(queue_logical_block_size(q));
         p->qlim->alignment_offset = 0;
         p->qlim->io_min = cpu_to_be32(queue_io_min(q));
         p->qlim->io_opt = cpu_to_be32(queue_io_opt(q));
         p->qlim->discard_enabled = 0;
 
         d_size = 0;
         u_size = 0;
         q_order_type = QUEUE_ORDERED_NONE;
         max_bio_size = DRBD_MAX_BIO_SIZE; /* ... multiple BIOs per peer_request */
     }
 
     if (peer_device->connection->agreed_pro_version <= 94)
         max_bio_size = min(max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
     else if (peer_device->connection->agreed_pro_version < 100)
         max_bio_size = min(max_bio_size, DRBD_MAX_BIO_SIZE_P95);
 
     p->d_size = cpu_to_be64(d_size);
     p->u_size = cpu_to_be64(u_size);
     if (trigger_reply)
         p->c_size = 0;
     else
         p->c_size = cpu_to_be64(get_capacity(device->vdisk));
     p->max_bio_size = cpu_to_be32(max_bio_size);
     p->queue_order_type = cpu_to_be16(q_order_type);
     p->dds_flags = cpu_to_be16(flags);
 
     return drbd_send_command(peer_device, sock, P_SIZES, packet_size, NULL, 0);
 }
 
 /**
  * drbd_send_current_state() - Sends the drbd state to the peer
  * @peer_device:    DRBD peer device.
  */
 int drbd_send_current_state(struct drbd_peer_device *peer_device)
 {
     struct drbd_socket *sock;
     struct p_state *p;
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     if (!p)
         return -EIO;
     p->state = cpu_to_be32(peer_device->device->state.i); /* Within the send mutex */
     return drbd_send_command(peer_device, sock, P_STATE, sizeof(*p), NULL, 0);
 }
 
 /**
  * drbd_send_state() - After a state change, sends the new state to the peer
  * @peer_device:      DRBD peer device.
  * @state:     the state to send, not necessarily the current state.
  *
  * Each state change queues an "after_state_ch" work, which will eventually
  * send the resulting new state to the peer. If more state changes happen
  * between queuing and processing of the after_state_ch work, we still
  * want to send each intermediary state in the order it occurred.
  */
 int drbd_send_state(struct drbd_peer_device *peer_device, union drbd_state state)
 {
     struct drbd_socket *sock;
     struct p_state *p;
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     if (!p)
         return -EIO;
     p->state = cpu_to_be32(state.i); /* Within the send mutex */
     return drbd_send_command(peer_device, sock, P_STATE, sizeof(*p), NULL, 0);
 }
 
 int drbd_send_state_req(struct drbd_peer_device *peer_device, union drbd_state mask, union drbd_state val)
 {
     struct drbd_socket *sock;
     struct p_req_state *p;
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     if (!p)
         return -EIO;
     p->mask = cpu_to_be32(mask.i);
     p->val = cpu_to_be32(val.i);
     return drbd_send_command(peer_device, sock, P_STATE_CHG_REQ, sizeof(*p), NULL, 0);
 }
 
 int conn_send_state_req(struct drbd_connection *connection, union drbd_state mask, union drbd_state val)
 {
     enum drbd_packet cmd;
     struct drbd_socket *sock;
     struct p_req_state *p;
 
     cmd = connection->agreed_pro_version < 100 ? P_STATE_CHG_REQ : P_CONN_ST_CHG_REQ;
     sock = &connection->data;
     p = conn_prepare_command(connection, sock);
     if (!p)
         return -EIO;
     p->mask = cpu_to_be32(mask.i);
     p->val = cpu_to_be32(val.i);
     return conn_send_command(connection, sock, cmd, sizeof(*p), NULL, 0);
 }
 
 void drbd_send_sr_reply(struct drbd_peer_device *peer_device, enum drbd_state_rv retcode)
 {
     struct drbd_socket *sock;
     struct p_req_state_reply *p;
 
     sock = &peer_device->connection->meta;
     p = drbd_prepare_command(peer_device, sock);
     if (p) {
         p->retcode = cpu_to_be32(retcode);
         drbd_send_command(peer_device, sock, P_STATE_CHG_REPLY, sizeof(*p), NULL, 0);
     }
 }
 
 void conn_send_sr_reply(struct drbd_connection *connection, enum drbd_state_rv retcode)
 {
     struct drbd_socket *sock;
     struct p_req_state_reply *p;
     enum drbd_packet cmd = connection->agreed_pro_version < 100 ? P_STATE_CHG_REPLY : P_CONN_ST_CHG_REPLY;
 
     sock = &connection->meta;
     p = conn_prepare_command(connection, sock);
     if (p) {
         p->retcode = cpu_to_be32(retcode);
         conn_send_command(connection, sock, cmd, sizeof(*p), NULL, 0);
     }
 }
 
 static void dcbp_set_code(struct p_compressed_bm *p, enum drbd_bitmap_code code)
 {
     BUG_ON(code & ~0xf);
     p->encoding = (p->encoding & ~0xf) | code;
 }
 
 static void dcbp_set_start(struct p_compressed_bm *p, int set)
 {
     p->encoding = (p->encoding & ~0x80) | (set ? 0x80 : 0);
 }
 
 static void dcbp_set_pad_bits(struct p_compressed_bm *p, int n)
 {
     BUG_ON(n & ~0x7);
     p->encoding = (p->encoding & (~0x7 << 4)) | (n << 4);
 }
 
 static int fill_bitmap_rle_bits(struct drbd_device *device,
              struct p_compressed_bm *p,
              unsigned int size,
              struct bm_xfer_ctx *c)
 {
     struct bitstream bs;
     unsigned long plain_bits;
     unsigned long tmp;
     unsigned long rl;
     unsigned len;
     unsigned toggle;
     int bits, use_rle;
 
     /* may we use this feature? */
     rcu_read_lock();
     use_rle = rcu_dereference(first_peer_device(device)->connection->net_conf)->use_rle;
     rcu_read_unlock();
     if (!use_rle || first_peer_device(device)->connection->agreed_pro_version < 90)
         return 0;
 
     if (c->bit_offset >= c->bm_bits)
         return 0; /* nothing to do. */
 
     /* use at most thus many bytes */
     bitstream_init(&bs, p->code, size, 0);
     memset(p->code, 0, size);
     /* plain bits covered in this code string */
     plain_bits = 0;
 
     /* p->encoding & 0x80 stores whether the first run length is set.
      * bit offset is implicit.
      * start with toggle == 2 to be able to tell the first iteration */
     toggle = 2;
 
     /* see how much plain bits we can stuff into one packet
      * using RLE and VLI. */
     do {
         tmp = (toggle == 0) ? _drbd_bm_find_next_zero(device, c->bit_offset)
                     : _drbd_bm_find_next(device, c->bit_offset);
         if (tmp == -1UL)
             tmp = c->bm_bits;
         rl = tmp - c->bit_offset;
 
         if (toggle == 2) { /* first iteration */
             if (rl == 0) {
                 /* the first checked bit was set,
                  * store start value, */
                 dcbp_set_start(p, 1);
                 /* but skip encoding of zero run length */
                 toggle = !toggle;
                 continue;
             }
             dcbp_set_start(p, 0);
         }
 
         /* paranoia: catch zero runlength.
          * can only happen if bitmap is modified while we scan it. */
         if (rl == 0) {
             drbd_err(device, "unexpected zero runlength while encoding bitmap "
                 "t:%u bo:%lu\n", toggle, c->bit_offset);
             return -1;
         }
 
         bits = vli_encode_bits(&bs, rl);
         if (bits == -ENOBUFS) /* buffer full */
             break;
         if (bits <= 0) {
             drbd_err(device, "error while encoding bitmap: %d\n", bits);
             return 0;
         }
 
         toggle = !toggle;
         plain_bits += rl;
         c->bit_offset = tmp;
     } while (c->bit_offset < c->bm_bits);
 
     len = bs.cur.b - p->code + !!bs.cur.bit;
 
     if (plain_bits < (len << 3)) {
         /* incompressible with this method.
          * we need to rewind both word and bit position. */
         c->bit_offset -= plain_bits;
         bm_xfer_ctx_bit_to_word_offset(c);
         c->bit_offset = c->word_offset * BITS_PER_LONG;
         return 0;
     }
 
     /* RLE + VLI was able to compress it just fine.
      * update c->word_offset. */
     bm_xfer_ctx_bit_to_word_offset(c);
 
     /* store pad_bits */
     dcbp_set_pad_bits(p, (8 - bs.cur.bit) & 0x7);
 
     return len;
 }
 
 /*
  * send_bitmap_rle_or_plain
  *
  * Return 0 when done, 1 when another iteration is needed, and a negative error
  * code upon failure.
  */
 static int
 send_bitmap_rle_or_plain(struct drbd_device *device, struct bm_xfer_ctx *c)
 {
     struct drbd_socket *sock = &first_peer_device(device)->connection->data;
     unsigned int header_size = drbd_header_size(first_peer_device(device)->connection);
     struct p_compressed_bm *p = sock->sbuf + header_size;
     int len, err;
 
     len = fill_bitmap_rle_bits(device, p,
             DRBD_SOCKET_BUFFER_SIZE - header_size - sizeof(*p), c);
     if (len < 0)
         return -EIO;
 
     if (len) {
         dcbp_set_code(p, RLE_VLI_Bits);
         err = __send_command(first_peer_device(device)->connection, device->vnr, sock,
                      P_COMPRESSED_BITMAP, sizeof(*p) + len,
                      NULL, 0);
         c->packets[0]++;
         c->bytes[0] += header_size + sizeof(*p) + len;
 
         if (c->bit_offset >= c->bm_bits)
             len = 0; /* DONE */
     } else {
         /* was not compressible.
          * send a buffer full of plain text bits instead. */
         unsigned int data_size;
         unsigned long num_words;
         unsigned long *p = sock->sbuf + header_size;
 
         data_size = DRBD_SOCKET_BUFFER_SIZE - header_size;
         num_words = min_t(size_t, data_size / sizeof(*p),
                   c->bm_words - c->word_offset);
         len = num_words * sizeof(*p);
         if (len)
             drbd_bm_get_lel(device, c->word_offset, num_words, p);
         err = __send_command(first_peer_device(device)->connection, device->vnr, sock, P_BITMAP, len, NULL, 0);
         c->word_offset += num_words;
         c->bit_offset = c->word_offset * BITS_PER_LONG;
 
         c->packets[1]++;
         c->bytes[1] += header_size + len;
 
         if (c->bit_offset > c->bm_bits)
             c->bit_offset = c->bm_bits;
     }
     if (!err) {
         if (len == 0) {
             INFO_bm_xfer_stats(device, "send", c);
             return 0;
         } else
             return 1;
     }
     return -EIO;
 }
 
 /* See the comment at receive_bitmap() */
 static int _drbd_send_bitmap(struct drbd_device *device)
 {
     struct bm_xfer_ctx c;
     int err;
 
     if (!expect(device->bitmap))
         return false;
 
     if (get_ldev(device)) {
         if (drbd_md_test_flag(device->ldev, MDF_FULL_SYNC)) {
             drbd_info(device, "Writing the whole bitmap, MDF_FullSync was set.\n");
             drbd_bm_set_all(device);
             if (drbd_bm_write(device)) {
                 /* write_bm did fail! Leave full sync flag set in Meta P_DATA
                  * but otherwise process as per normal - need to tell other
                  * side that a full resync is required! */
                 drbd_err(device, "Failed to write bitmap to disk!\n");
             } else {
                 drbd_md_clear_flag(device, MDF_FULL_SYNC);
                 drbd_md_sync(device);
             }
         }
         put_ldev(device);
     }
 
     c = (struct bm_xfer_ctx) {
         .bm_bits = drbd_bm_bits(device),
         .bm_words = drbd_bm_words(device),
     };
 
     do {
         err = send_bitmap_rle_or_plain(device, &c);
     } while (err > 0);
 
     return err == 0;
 }
 
 int drbd_send_bitmap(struct drbd_device *device)
 {
     struct drbd_socket *sock = &first_peer_device(device)->connection->data;
     int err = -1;
 
     mutex_lock(&sock->mutex);
     if (sock->socket)
         err = !_drbd_send_bitmap(device);
     mutex_unlock(&sock->mutex);
     return err;
 }
 
 void drbd_send_b_ack(struct drbd_connection *connection, u32 barrier_nr, u32 set_size)
 {
     struct drbd_socket *sock;
     struct p_barrier_ack *p;
 
     if (connection->cstate < C_WF_REPORT_PARAMS)
         return;
 
     sock = &connection->meta;
     p = conn_prepare_command(connection, sock);
     if (!p)
         return;
     p->barrier = barrier_nr;
     p->set_size = cpu_to_be32(set_size);
     conn_send_command(connection, sock, P_BARRIER_ACK, sizeof(*p), NULL, 0);
 }
 
 /**
  * _drbd_send_ack() - Sends an ack packet
  * @peer_device:    DRBD peer device.
  * @cmd:        Packet command code.
  * @sector:     sector, needs to be in big endian byte order
  * @blksize:        size in byte, needs to be in big endian byte order
  * @block_id:       Id, big endian byte order
  */
 static int _drbd_send_ack(struct drbd_peer_device *peer_device, enum drbd_packet cmd,
               u64 sector, u32 blksize, u64 block_id)
 {
     struct drbd_socket *sock;
     struct p_block_ack *p;
 
     if (peer_device->device->state.conn < C_CONNECTED)
         return -EIO;
 
     sock = &peer_device->connection->meta;
     p = drbd_prepare_command(peer_device, sock);
     if (!p)
         return -EIO;
     p->sector = sector;
     p->block_id = block_id;
     p->blksize = blksize;
     p->seq_num = cpu_to_be32(atomic_inc_return(&peer_device->device->packet_seq));
     return drbd_send_command(peer_device, sock, cmd, sizeof(*p), NULL, 0);
 }
 
 /* dp->sector and dp->block_id already/still in network byte order,
  * data_size is payload size according to dp->head,
  * and may need to be corrected for digest size. */
 void drbd_send_ack_dp(struct drbd_peer_device *peer_device, enum drbd_packet cmd,
               struct p_data *dp, int data_size)
 {
     if (peer_device->connection->peer_integrity_tfm)
         data_size -= crypto_shash_digestsize(peer_device->connection->peer_integrity_tfm);
     _drbd_send_ack(peer_device, cmd, dp->sector, cpu_to_be32(data_size),
                dp->block_id);
 }
 
 void drbd_send_ack_rp(struct drbd_peer_device *peer_device, enum drbd_packet cmd,
               struct p_block_req *rp)
 {
     _drbd_send_ack(peer_device, cmd, rp->sector, rp->blksize, rp->block_id);
 }
 
 /**
  * drbd_send_ack() - Sends an ack packet
  * @peer_device:    DRBD peer device
  * @cmd:        packet command code
  * @peer_req:       peer request
  */
 int drbd_send_ack(struct drbd_peer_device *peer_device, enum drbd_packet cmd,
           struct drbd_peer_request *peer_req)
 {
     return _drbd_send_ack(peer_device, cmd,
                   cpu_to_be64(peer_req->i.sector),
                   cpu_to_be32(peer_req->i.size),
                   peer_req->block_id);
 }
 
 /* This function misuses the block_id field to signal if the blocks
  * are is sync or not. */
 int drbd_send_ack_ex(struct drbd_peer_device *peer_device, enum drbd_packet cmd,
              sector_t sector, int blksize, u64 block_id)
 {
     return _drbd_send_ack(peer_device, cmd,
                   cpu_to_be64(sector),
                   cpu_to_be32(blksize),
                   cpu_to_be64(block_id));
 }
 
 int drbd_send_rs_deallocated(struct drbd_peer_device *peer_device,
                  struct drbd_peer_request *peer_req)
 {
     struct drbd_socket *sock;
     struct p_block_desc *p;
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     if (!p)
         return -EIO;
     p->sector = cpu_to_be64(peer_req->i.sector);
     p->blksize = cpu_to_be32(peer_req->i.size);
     p->pad = 0;
     return drbd_send_command(peer_device, sock, P_RS_DEALLOCATED, sizeof(*p), NULL, 0);
 }
 
 int drbd_send_drequest(struct drbd_peer_device *peer_device, int cmd,
                sector_t sector, int size, u64 block_id)
 {
     struct drbd_socket *sock;
     struct p_block_req *p;
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     if (!p)
         return -EIO;
     p->sector = cpu_to_be64(sector);
     p->block_id = block_id;
     p->blksize = cpu_to_be32(size);
     return drbd_send_command(peer_device, sock, cmd, sizeof(*p), NULL, 0);
 }
 
 int drbd_send_drequest_csum(struct drbd_peer_device *peer_device, sector_t sector, int size,
                 void *digest, int digest_size, enum drbd_packet cmd)
 {
     struct drbd_socket *sock;
     struct p_block_req *p;
 
     /* FIXME: Put the digest into the preallocated socket buffer.  */
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     if (!p)
         return -EIO;
     p->sector = cpu_to_be64(sector);
     p->block_id = ID_SYNCER /* unused */;
     p->blksize = cpu_to_be32(size);
     return drbd_send_command(peer_device, sock, cmd, sizeof(*p), digest, digest_size);
 }
 
 int drbd_send_ov_request(struct drbd_peer_device *peer_device, sector_t sector, int size)
 {
     struct drbd_socket *sock;
     struct p_block_req *p;
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     if (!p)
         return -EIO;
     p->sector = cpu_to_be64(sector);
     p->block_id = ID_SYNCER /* unused */;
     p->blksize = cpu_to_be32(size);
     return drbd_send_command(peer_device, sock, P_OV_REQUEST, sizeof(*p), NULL, 0);
 }
 
 /* called on sndtimeo
  * returns false if we should retry,
  * true if we think connection is dead
  */
 static int we_should_drop_the_connection(struct drbd_connection *connection, struct socket *sock)
 {
     int drop_it;
     /* long elapsed = (long)(jiffies - device->last_received); */
 
     drop_it =   connection->meta.socket == sock
         || !connection->ack_receiver.task
         || get_t_state(&connection->ack_receiver) != RUNNING
         || connection->cstate < C_WF_REPORT_PARAMS;
 
     if (drop_it)
         return true;
 
     drop_it = !--connection->ko_count;
     if (!drop_it) {
         drbd_err(connection, "[%s/%d] sock_sendmsg time expired, ko = %u\n",
              current->comm, current->pid, connection->ko_count);
         request_ping(connection);
     }
 
     return drop_it; /* && (device->state == R_PRIMARY) */;
 }
 
 static void drbd_update_congested(struct drbd_connection *connection)
 {
     struct sock *sk = connection->data.socket->sk;
     if (sk->sk_wmem_queued > sk->sk_sndbuf * 4 / 5)
         set_bit(NET_CONGESTED, &connection->flags);
 }
 
 /* The idea of sendpage seems to be to put some kind of reference
  * to the page into the skb, and to hand it over to the NIC. In
  * this process get_page() gets called.
  *
  * As soon as the page was really sent over the network put_page()
  * gets called by some part of the network layer. [ NIC driver? ]
  *
  * [ get_page() / put_page() increment/decrement the count. If count
  *   reaches 0 the page will be freed. ]
  *
  * This works nicely with pages from FSs.
  * But this means that in protocol A we might signal IO completion too early!
  *
  * In order not to corrupt data during a resync we must make sure
  * that we do not reuse our own buffer pages (EEs) to early, therefore
  * we have the net_ee list.
  *
  * XFS seems to have problems, still, it submits pages with page_count == 0!
  * As a workaround, we disable sendpage on pages
  * with page_count == 0 or PageSlab.
  */
 static int _drbd_no_send_page(struct drbd_peer_device *peer_device, struct page *page,
                   int offset, size_t size, unsigned msg_flags)
 {
     struct socket *socket;
     void *addr;
     int err;
 
     socket = peer_device->connection->data.socket;
     addr = kmap(page) + offset;
     err = drbd_send_all(peer_device->connection, socket, addr, size, msg_flags);
     kunmap(page);
     if (!err)
         peer_device->device->send_cnt += size >> 9;
     return err;
 }
 
 static int _drbd_send_page(struct drbd_peer_device *peer_device, struct page *page,
             int offset, size_t size, unsigned msg_flags)
 {
     struct socket *socket = peer_device->connection->data.socket;
     int len = size;
     int err = -EIO;
 
     /* e.g. XFS meta- & log-data is in slab pages, which have a
      * page_count of 0 and/or have PageSlab() set.
      * we cannot use send_page for those, as that does get_page();
      * put_page(); and would cause either a VM_BUG directly, or
      * __page_cache_release a page that would actually still be referenced
      * by someone, leading to some obscure delayed Oops somewhere else. */
     if (drbd_disable_sendpage || !sendpage_ok(page))
         return _drbd_no_send_page(peer_device, page, offset, size, msg_flags);
 
     msg_flags |= MSG_NOSIGNAL;
     drbd_update_congested(peer_device->connection);
     do {
         int sent;
 
         sent = socket->ops->sendpage(socket, page, offset, len, msg_flags);
         if (sent <= 0) {
             if (sent == -EAGAIN) {
                 if (we_should_drop_the_connection(peer_device->connection, socket))
                     break;
                 continue;
             }
             drbd_warn(peer_device->device, "%s: size=%d len=%d sent=%d\n",
                  __func__, (int)size, len, sent);
             if (sent < 0)
                 err = sent;
             break;
         }
         len    -= sent;
         offset += sent;
     } while (len > 0 /* THINK && device->cstate >= C_CONNECTED*/);
     clear_bit(NET_CONGESTED, &peer_device->connection->flags);
 
     if (len == 0) {
         err = 0;
         peer_device->device->send_cnt += size >> 9;
     }
     return err;
 }
 
 static int _drbd_send_bio(struct drbd_peer_device *peer_device, struct bio *bio)
 {
     struct bio_vec bvec;
     struct bvec_iter iter;
 
     /* hint all but last page with MSG_MORE */
     bio_for_each_segment(bvec, bio, iter) {
         int err;
 
         err = _drbd_no_send_page(peer_device, bvec.bv_page,
                      bvec.bv_offset, bvec.bv_len,
                      bio_iter_last(bvec, iter)
                      ? 0 : MSG_MORE);
         if (err)
             return err;
     }
     return 0;
 }
 
 static int _drbd_send_zc_bio(struct drbd_peer_device *peer_device, struct bio *bio)
 {
     struct bio_vec bvec;
     struct bvec_iter iter;
 
     /* hint all but last page with MSG_MORE */
     bio_for_each_segment(bvec, bio, iter) {
         int err;
 
         err = _drbd_send_page(peer_device, bvec.bv_page,
                       bvec.bv_offset, bvec.bv_len,
                       bio_iter_last(bvec, iter) ? 0 : MSG_MORE);
         if (err)
             return err;
     }
     return 0;
 }
 
 static int _drbd_send_zc_ee(struct drbd_peer_device *peer_device,
                 struct drbd_peer_request *peer_req)
 {
     struct page *page = peer_req->pages;
     unsigned len = peer_req->i.size;
     int err;
 
     /* hint all but last page with MSG_MORE */
     page_chain_for_each(page) {
         unsigned l = min_t(unsigned, len, PAGE_SIZE);
 
         err = _drbd_send_page(peer_device, page, 0, l,
                       page_chain_next(page) ? MSG_MORE : 0);
         if (err)
             return err;
         len -= l;
     }
     return 0;
 }
 
 static u32 bio_flags_to_wire(struct drbd_connection *connection,
                  struct bio *bio)
 {
     if (connection->agreed_pro_version >= 95)
         return  (bio->bi_opf & REQ_SYNC ? DP_RW_SYNC : 0) |
             (bio->bi_opf & REQ_FUA ? DP_FUA : 0) |
             (bio->bi_opf & REQ_PREFLUSH ? DP_FLUSH : 0) |
             (bio_op(bio) == REQ_OP_DISCARD ? DP_DISCARD : 0) |
             (bio_op(bio) == REQ_OP_WRITE_ZEROES ?
               ((connection->agreed_features & DRBD_FF_WZEROES) ?
                (DP_ZEROES |(!(bio->bi_opf & REQ_NOUNMAP) ? DP_DISCARD : 0))
                : DP_DISCARD)
             : 0);
     else
         return bio->bi_opf & REQ_SYNC ? DP_RW_SYNC : 0;
 }
 
 /* Used to send write or TRIM aka REQ_OP_DISCARD requests
  * R_PRIMARY -> Peer    (P_DATA, P_TRIM)
  */
 int drbd_send_dblock(struct drbd_peer_device *peer_device, struct drbd_request *req)
 {
     struct drbd_device *device = peer_device->device;
     struct drbd_socket *sock;
     struct p_data *p;
     void *digest_out;
     unsigned int dp_flags = 0;
     int digest_size;
     int err;
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     digest_size = peer_device->connection->integrity_tfm ?
               crypto_shash_digestsize(peer_device->connection->integrity_tfm) : 0;
 
     if (!p)
         return -EIO;
     p->sector = cpu_to_be64(req->i.sector);
     p->block_id = (unsigned long)req;
     p->seq_num = cpu_to_be32(atomic_inc_return(&device->packet_seq));
     dp_flags = bio_flags_to_wire(peer_device->connection, req->master_bio);
     if (device->state.conn >= C_SYNC_SOURCE &&
         device->state.conn <= C_PAUSED_SYNC_T)
         dp_flags |= DP_MAY_SET_IN_SYNC;
     if (peer_device->connection->agreed_pro_version >= 100) {
         if (req->rq_state & RQ_EXP_RECEIVE_ACK)
             dp_flags |= DP_SEND_RECEIVE_ACK;
         /* During resync, request an explicit write ack,
          * even in protocol != C */
         if (req->rq_state & RQ_EXP_WRITE_ACK
         || (dp_flags & DP_MAY_SET_IN_SYNC))
             dp_flags |= DP_SEND_WRITE_ACK;
     }
     p->dp_flags = cpu_to_be32(dp_flags);
 
     if (dp_flags & (DP_DISCARD|DP_ZEROES)) {
         enum drbd_packet cmd = (dp_flags & DP_ZEROES) ? P_ZEROES : P_TRIM;
         struct p_trim *t = (struct p_trim*)p;
         t->size = cpu_to_be32(req->i.size);
         err = __send_command(peer_device->connection, device->vnr, sock, cmd, sizeof(*t), NULL, 0);
         goto out;
     }
     digest_out = p + 1;
 
     /* our digest is still only over the payload.
      * TRIM does not carry any payload. */
     if (digest_size)
         drbd_csum_bio(peer_device->connection->integrity_tfm, req->master_bio, digest_out);
     err = __send_command(peer_device->connection, device->vnr, sock, P_DATA,
                  sizeof(*p) + digest_size, NULL, req->i.size);
     if (!err) {
         /* For protocol A, we have to memcpy the payload into
          * socket buffers, as we may complete right away
          * as soon as we handed it over to tcp, at which point the data
          * pages may become invalid.
          *
          * For data-integrity enabled, we copy it as well, so we can be
          * sure that even if the bio pages may still be modified, it
          * won't change the data on the wire, thus if the digest checks
          * out ok after sending on this side, but does not fit on the
          * receiving side, we sure have detected corruption elsewhere.
          */
         if (!(req->rq_state & (RQ_EXP_RECEIVE_ACK | RQ_EXP_WRITE_ACK)) || digest_size)
             err = _drbd_send_bio(peer_device, req->master_bio);
         else
             err = _drbd_send_zc_bio(peer_device, req->master_bio);
 
         /* double check digest, sometimes buffers have been modified in flight. */
         if (digest_size > 0 && digest_size <= 64) {
             /* 64 byte, 512 bit, is the largest digest size
              * currently supported in kernel crypto. */
             unsigned char digest[64];
             drbd_csum_bio(peer_device->connection->integrity_tfm, req->master_bio, digest);
             if (memcmp(p + 1, digest, digest_size)) {
                 drbd_warn(device,
                     "Digest mismatch, buffer modified by upper layers during write: %llus +%u\n",
                     (unsigned long long)req->i.sector, req->i.size);
             }
         } /* else if (digest_size > 64) {
              ... Be noisy about digest too large ...
         } */
     }
 out:
     mutex_unlock(&sock->mutex);  /* locked by drbd_prepare_command() */
 
     return err;
 }
 
 /* answer packet, used to send data back for read requests:
  *  Peer       -> (diskless) R_PRIMARY   (P_DATA_REPLY)
  *  C_SYNC_SOURCE -> C_SYNC_TARGET         (P_RS_DATA_REPLY)
  */
 int drbd_send_block(struct drbd_peer_device *peer_device, enum drbd_packet cmd,
             struct drbd_peer_request *peer_req)
 {
     struct drbd_device *device = peer_device->device;
     struct drbd_socket *sock;
     struct p_data *p;
     int err;
     int digest_size;
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
 
     digest_size = peer_device->connection->integrity_tfm ?
               crypto_shash_digestsize(peer_device->connection->integrity_tfm) : 0;
 
     if (!p)
         return -EIO;
     p->sector = cpu_to_be64(peer_req->i.sector);
     p->block_id = peer_req->block_id;
     p->seq_num = 0;  /* unused */
     p->dp_flags = 0;
     if (digest_size)
         drbd_csum_ee(peer_device->connection->integrity_tfm, peer_req, p + 1);
     err = __send_command(peer_device->connection, device->vnr, sock, cmd, sizeof(*p) + digest_size, NULL, peer_req->i.size);
     if (!err)
         err = _drbd_send_zc_ee(peer_device, peer_req);
     mutex_unlock(&sock->mutex);  /* locked by drbd_prepare_command() */
 
     return err;
 }
 
 int drbd_send_out_of_sync(struct drbd_peer_device *peer_device, struct drbd_request *req)
 {
     struct drbd_socket *sock;
     struct p_block_desc *p;
 
     sock = &peer_device->connection->data;
     p = drbd_prepare_command(peer_device, sock);
     if (!p)
         return -EIO;
     p->sector = cpu_to_be64(req->i.sector);
     p->blksize = cpu_to_be32(req->i.size);
     return drbd_send_command(peer_device, sock, P_OUT_OF_SYNC, sizeof(*p), NULL, 0);
 }
 
 /*
   drbd_send distinguishes two cases:
 
   Packets sent via the data socket "sock"
   and packets sent via the meta data socket "msock"
 
             sock                      msock
   -----------------+-------------------------+------------------------------
   timeout           conf.timeout / 2          conf.timeout / 2
   timeout action    send a ping via msock     Abort communication
                           and close all sockets
 */
 
 /*
  * you must have down()ed the appropriate [m]sock_mutex elsewhere!
  */
 int drbd_send(struct drbd_connection *connection, struct socket *sock,
           void *buf, size_t size, unsigned msg_flags)
 {
     struct kvec iov = {.iov_base = buf, .iov_len = size};
     struct msghdr msg = {.msg_flags = msg_flags | MSG_NOSIGNAL};
     int rv, sent = 0;
 
     if (!sock)
         return -EBADR;
 
     /* THINK  if (signal_pending) return ... ? */
 
     iov_iter_kvec(&msg.msg_iter, WRITE, &iov, 1, size);
 
     if (sock == connection->data.socket) {
         rcu_read_lock();
         connection->ko_count = rcu_dereference(connection->net_conf)->ko_count;
         rcu_read_unlock();
         drbd_update_congested(connection);
     }
     do {
         rv = sock_sendmsg(sock, &msg);
         if (rv == -EAGAIN) {
             if (we_should_drop_the_connection(connection, sock))
                 break;
             else
                 continue;
         }
         if (rv == -EINTR) {
             flush_signals(current);
             rv = 0;
         }
         if (rv < 0)
             break;
         sent += rv;
     } while (sent < size);
 
     if (sock == connection->data.socket)
         clear_bit(NET_CONGESTED, &connection->flags);
 
     if (rv <= 0) {
         if (rv != -EAGAIN) {
             drbd_err(connection, "%s_sendmsg returned %d\n",
                  sock == connection->meta.socket ? "msock" : "sock",
                  rv);
             conn_request_state(connection, NS(conn, C_BROKEN_PIPE), CS_HARD);
         } else
             conn_request_state(connection, NS(conn, C_TIMEOUT), CS_HARD);
     }
 
     return sent;
 }
 
 /*
  * drbd_send_all  -  Send an entire buffer
  *
  * Returns 0 upon success and a negative error value otherwise.
  */
 int drbd_send_all(struct drbd_connection *connection, struct socket *sock, void *buffer,
           size_t size, unsigned msg_flags)
 {
     int err;
 
     err = drbd_send(connection, sock, buffer, size, msg_flags);
     if (err < 0)
         return err;
     if (err != size)
         return -EIO;
     return 0;
 }
 
 static int drbd_open(struct block_device *bdev, fmode_t mode)
 {
     struct drbd_device *device = bdev->bd_disk->private_data;
     unsigned long flags;
     int rv = 0;
 
     mutex_lock(&drbd_main_mutex);
     spin_lock_irqsave(&device->resource->req_lock, flags);
     /* to have a stable device->state.role
      * and no race with updating open_cnt */
 
     if (device->state.role != R_PRIMARY) {
         if (mode & FMODE_WRITE)
             rv = -EROFS;
         else if (!drbd_allow_oos)
             rv = -EMEDIUMTYPE;
     }
 
     if (!rv)
         device->open_cnt++;
     spin_unlock_irqrestore(&device->resource->req_lock, flags);
     mutex_unlock(&drbd_main_mutex);
 
     return rv;
 }
 
 static void drbd_release(struct gendisk *gd, fmode_t mode)
 {
     struct drbd_device *device = gd->private_data;
     mutex_lock(&drbd_main_mutex);
     device->open_cnt--;
     mutex_unlock(&drbd_main_mutex);
 }
 
 /* need to hold resource->req_lock */
 void drbd_queue_unplug(struct drbd_device *device)
 {
     if (device->state.pdsk >= D_INCONSISTENT && device->state.conn >= C_CONNECTED) {
         D_ASSERT(device, device->state.role == R_PRIMARY);
         if (test_and_clear_bit(UNPLUG_REMOTE, &device->flags)) {
             drbd_queue_work_if_unqueued(
                 &first_peer_device(device)->connection->sender_work,
                 &device->unplug_work);
         }
     }
 }
 
 static void drbd_set_defaults(struct drbd_device *device)
 {
     /* Beware! The actual layout differs
      * between big endian and little endian */
     device->state = (union drbd_dev_state) {
         { .role = R_SECONDARY,
           .peer = R_UNKNOWN,
           .conn = C_STANDALONE,
           .disk = D_DISKLESS,
           .pdsk = D_UNKNOWN,
         } };
 }
 
 void drbd_init_set_defaults(struct drbd_device *device)
 {
     /* the memset(,0,) did most of this.
      * note: only assignments, no allocation in here */
 
     drbd_set_defaults(device);
 
     atomic_set(&device->ap_bio_cnt, 0);
     atomic_set(&device->ap_actlog_cnt, 0);
     atomic_set(&device->ap_pending_cnt, 0);
     atomic_set(&device->rs_pending_cnt, 0);
     atomic_set(&device->unacked_cnt, 0);
     atomic_set(&device->local_cnt, 0);
     atomic_set(&device->pp_in_use_by_net, 0);
     atomic_set(&device->rs_sect_in, 0);
     atomic_set(&device->rs_sect_ev, 0);
     atomic_set(&device->ap_in_flight, 0);
     atomic_set(&device->md_io.in_use, 0);
 
     mutex_init(&device->own_state_mutex);
     device->state_mutex = &device->own_state_mutex;
 
     spin_lock_init(&device->al_lock);
     spin_lock_init(&device->peer_seq_lock);
 
     INIT_LIST_HEAD(&device->active_ee);
     INIT_LIST_HEAD(&device->sync_ee);
     INIT_LIST_HEAD(&device->done_ee);
     INIT_LIST_HEAD(&device->read_ee);
     INIT_LIST_HEAD(&device->net_ee);
     INIT_LIST_HEAD(&device->resync_reads);
     INIT_LIST_HEAD(&device->resync_work.list);
     INIT_LIST_HEAD(&device->unplug_work.list);
     INIT_LIST_HEAD(&device->bm_io_work.w.list);
     INIT_LIST_HEAD(&device->pending_master_completion[0]);
     INIT_LIST_HEAD(&device->pending_master_completion[1]);
     INIT_LIST_HEAD(&device->pending_completion[0]);
     INIT_LIST_HEAD(&device->pending_completion[1]);
 
     device->resync_work.cb  = w_resync_timer;
     device->unplug_work.cb  = w_send_write_hint;
     device->bm_io_work.w.cb = w_bitmap_io;
 
     timer_setup(&device->resync_timer, resync_timer_fn, 0);
     timer_setup(&device->md_sync_timer, md_sync_timer_fn, 0);
     timer_setup(&device->start_resync_timer, start_resync_timer_fn, 0);
     timer_setup(&device->request_timer, request_timer_fn, 0);
 
     init_waitqueue_head(&device->misc_wait);
     init_waitqueue_head(&device->state_wait);
     init_waitqueue_head(&device->ee_wait);
     init_waitqueue_head(&device->al_wait);
     init_waitqueue_head(&device->seq_wait);
 
     device->resync_wenr = LC_FREE;
     device->peer_max_bio_size = DRBD_MAX_BIO_SIZE_SAFE;
     device->local_max_bio_size = DRBD_MAX_BIO_SIZE_SAFE;
 }
 
 void drbd_set_my_capacity(struct drbd_device *device, sector_t size)
 {
     char ppb[10];
 
     set_capacity_and_notify(device->vdisk, size);
 
     drbd_info(device, "size = %s (%llu KB)\n",
         ppsize(ppb, size>>1), (unsigned long long)size>>1);
 }
 
 void drbd_device_cleanup(struct drbd_device *device)
 {
     int i;
     if (first_peer_device(device)->connection->receiver.t_state != NONE)
         drbd_err(device, "ASSERT FAILED: receiver t_state == %d expected 0.\n",
                 first_peer_device(device)->connection->receiver.t_state);
 
     device->al_writ_cnt  =
     device->bm_writ_cnt  =
     device->read_cnt     =
     device->recv_cnt     =
     device->send_cnt     =
     device->writ_cnt     =
     device->p_size       =
     device->rs_start     =
     device->rs_total     =
     device->rs_failed    = 0;
     device->rs_last_events = 0;
     device->rs_last_sect_ev = 0;
     for (i = 0; i < DRBD_SYNC_MARKS; i++) {
         device->rs_mark_left[i] = 0;
         device->rs_mark_time[i] = 0;
     }
     D_ASSERT(device, first_peer_device(device)->connection->net_conf == NULL);
 
     set_capacity_and_notify(device->vdisk, 0);
     if (device->bitmap) {
         /* maybe never allocated. */
         drbd_bm_resize(device, 0, 1);
         drbd_bm_cleanup(device);
     }
 
     drbd_backing_dev_free(device, device->ldev);
     device->ldev = NULL;
 
     clear_bit(AL_SUSPENDED, &device->flags);
 
     D_ASSERT(device, list_empty(&device->active_ee));
     D_ASSERT(device, list_empty(&device->sync_ee));
     D_ASSERT(device, list_empty(&device->done_ee));
     D_ASSERT(device, list_empty(&device->read_ee));
     D_ASSERT(device, list_empty(&device->net_ee));
     D_ASSERT(device, list_empty(&device->resync_reads));
     D_ASSERT(device, list_empty(&first_peer_device(device)->connection->sender_work.q));
     D_ASSERT(device, list_empty(&device->resync_work.list));
     D_ASSERT(device, list_empty(&device->unplug_work.list));
 
     drbd_set_defaults(device);
 }
 
 
 static void drbd_destroy_mempools(void)
 {
     struct page *page;
 
     while (drbd_pp_pool) {
         page = drbd_pp_pool;
         drbd_pp_pool = (struct page *)page_private(page);
         __free_page(page);
         drbd_pp_vacant--;
     }
 
     /* D_ASSERT(device, atomic_read(&drbd_pp_vacant)==0); */
 
     bioset_exit(&drbd_io_bio_set);
     bioset_exit(&drbd_md_io_bio_set);
     mempool_exit(&drbd_md_io_page_pool);
     mempool_exit(&drbd_ee_mempool);
     mempool_exit(&drbd_request_mempool);
     kmem_cache_destroy(drbd_ee_cache);
     kmem_cache_destroy(drbd_request_cache);
     kmem_cache_destroy(drbd_bm_ext_cache);
     kmem_cache_destroy(drbd_al_ext_cache);
 
     drbd_ee_cache        = NULL;
     drbd_request_cache   = NULL;
     drbd_bm_ext_cache    = NULL;
     drbd_al_ext_cache    = NULL;
 
     return;
 }
 
 static int drbd_create_mempools(void)
 {
     struct page *page;
     const int number = (DRBD_MAX_BIO_SIZE/PAGE_SIZE) * drbd_minor_count;
     int i, ret;
 
     /* caches */
     drbd_request_cache = kmem_cache_create(
         "drbd_req", sizeof(struct drbd_request), 0, 0, NULL);
     if (drbd_request_cache == NULL)
         goto Enomem;
 
     drbd_ee_cache = kmem_cache_create(
         "drbd_ee", sizeof(struct drbd_peer_request), 0, 0, NULL);
     if (drbd_ee_cache == NULL)
         goto Enomem;
 
     drbd_bm_ext_cache = kmem_cache_create(
         "drbd_bm", sizeof(struct bm_extent), 0, 0, NULL);
     if (drbd_bm_ext_cache == NULL)
         goto Enomem;
 
     drbd_al_ext_cache = kmem_cache_create(
         "drbd_al", sizeof(struct lc_element), 0, 0, NULL);
     if (drbd_al_ext_cache == NULL)
         goto Enomem;
 
     /* mempools */
     ret = bioset_init(&drbd_io_bio_set, BIO_POOL_SIZE, 0, 0);
     if (ret)
         goto Enomem;
 
     ret = bioset_init(&drbd_md_io_bio_set, DRBD_MIN_POOL_PAGES, 0,
               BIOSET_NEED_BVECS);
     if (ret)
         goto Enomem;
 
     ret = mempool_init_page_pool(&drbd_md_io_page_pool, DRBD_MIN_POOL_PAGES, 0);
     if (ret)
         goto Enomem;
 
     ret = mempool_init_slab_pool(&drbd_request_mempool, number,
                      drbd_request_cache);
     if (ret)
         goto Enomem;
 
     ret = mempool_init_slab_pool(&drbd_ee_mempool, number, drbd_ee_cache);
     if (ret)
         goto Enomem;
 
     for (i = 0; i < number; i++) {
         page = alloc_page(GFP_HIGHUSER);
         if (!page)
             goto Enomem;
         set_page_private(page, (unsigned long)drbd_pp_pool);
         drbd_pp_pool = page;
     }
     drbd_pp_vacant = number;
 
     return 0;
 
 Enomem:
     drbd_destroy_mempools(); /* in case we allocated some */
     return -ENOMEM;
 }
 
 static void drbd_release_all_peer_reqs(struct drbd_device *device)
 {
     int rr;
 
     rr = drbd_free_peer_reqs(device, &device->active_ee);
     if (rr)
         drbd_err(device, "%d EEs in active list found!\n", rr);
 
     rr = drbd_free_peer_reqs(device, &device->sync_ee);
     if (rr)
         drbd_err(device, "%d EEs in sync list found!\n", rr);
 
     rr = drbd_free_peer_reqs(device, &device->read_ee);
     if (rr)
         drbd_err(device, "%d EEs in read list found!\n", rr);
 
     rr = drbd_free_peer_reqs(device, &device->done_ee);
     if (rr)
         drbd_err(device, "%d EEs in done list found!\n", rr);
 
     rr = drbd_free_peer_reqs(device, &device->net_ee);
     if (rr)
         drbd_err(device, "%d EEs in net list found!\n", rr);
 }
 
 /* caution. no locking. */
 void drbd_destroy_device(struct kref *kref)
 {
     struct drbd_device *device = container_of(kref, struct drbd_device, kref);
     struct drbd_resource *resource = device->resource;
     struct drbd_peer_device *peer_device, *tmp_peer_device;
 
     del_timer_sync(&device->request_timer);
 
     /* paranoia asserts */
     D_ASSERT(device, device->open_cnt == 0);
     /* end paranoia asserts */
 
     /* cleanup stuff that may have been allocated during
      * device (re-)configuration or state changes */
 
     drbd_backing_dev_free(device, device->ldev);
     device->ldev = NULL;
 
     drbd_release_all_peer_reqs(device);
 
     lc_destroy(device->act_log);
     lc_destroy(device->resync);
 
     kfree(device->p_uuid);
     /* device->p_uuid = NULL; */
 
     if (device->bitmap) /* should no longer be there. */
         drbd_bm_cleanup(device);
     __free_page(device->md_io.page);
     put_disk(device->vdisk);
     kfree(device->rs_plan_s);
 
     /* not for_each_connection(connection, resource):
      * those may have been cleaned up and disassociated already.
      */
     for_each_peer_device_safe(peer_device, tmp_peer_device, device) {
         kref_put(&peer_device->connection->kref, drbd_destroy_connection);
         kfree(peer_device);
     }
     memset(device, 0xfd, sizeof(*device));
     kfree(device);
     kref_put(&resource->kref, drbd_destroy_resource);
 }
 
 /* One global retry thread, if we need to push back some bio and have it
  * reinserted through our make request function.
  */
 static struct retry_worker {
     struct workqueue_struct *wq;
     struct work_struct worker;
 
     spinlock_t lock;
     struct list_head writes;
 } retry;
 
 static void do_retry(struct work_struct *ws)
 {
     struct retry_worker *retry = container_of(ws, struct retry_worker, worker);
     LIST_HEAD(writes);
     struct drbd_request *req, *tmp;
 
     spin_lock_irq(&retry->lock);
     list_splice_init(&retry->writes, &writes);
     spin_unlock_irq(&retry->lock);
 
     list_for_each_entry_safe(req, tmp, &writes, tl_requests) {
         struct drbd_device *device = req->device;
         struct bio *bio = req->master_bio;
         bool expected;
 
         expected =
             expect(atomic_read(&req->completion_ref) == 0) &&
             expect(req->rq_state & RQ_POSTPONED) &&
             expect((req->rq_state & RQ_LOCAL_PENDING) == 0 ||
                 (req->rq_state & RQ_LOCAL_ABORTED) != 0);
 
         if (!expected)
             drbd_err(device, "req=%p completion_ref=%d rq_state=%x\n",
                 req, atomic_read(&req->completion_ref),
                 req->rq_state);
 
         /* We still need to put one kref associated with the
          * "completion_ref" going zero in the code path that queued it
          * here.  The request object may still be referenced by a
          * frozen local req->private_bio, in case we force-detached.
          */
         kref_put(&req->kref, drbd_req_destroy);
 
         /* A single suspended or otherwise blocking device may stall
          * all others as well.  Fortunately, this code path is to
          * recover from a situation that "should not happen":
          * concurrent writes in multi-primary setup.
          * In a "normal" lifecycle, this workqueue is supposed to be
          * destroyed without ever doing anything.
          * If it turns out to be an issue anyways, we can do per
          * resource (replication group) or per device (minor) retry
          * workqueues instead.
          */
 
         /* We are not just doing submit_bio_noacct(),
          * as we want to keep the start_time information. */
         inc_ap_bio(device);
         __drbd_make_request(device, bio);
     }
 }
 
 /* called via drbd_req_put_completion_ref(),
  * holds resource->req_lock */
 void drbd_restart_request(struct drbd_request *req)
 {
     unsigned long flags;
     spin_lock_irqsave(&retry.lock, flags);
     list_move_tail(&req->tl_requests, &retry.writes);
     spin_unlock_irqrestore(&retry.lock, flags);
 
     /* Drop the extra reference that would otherwise
      * have been dropped by complete_master_bio.
      * do_retry() needs to grab a new one. */
     dec_ap_bio(req->device);
 
     queue_work(retry.wq, &retry.worker);
 }
 
 void drbd_destroy_resource(struct kref *kref)
 {
     struct drbd_resource *resource =
         container_of(kref, struct drbd_resource, kref);
 
     idr_destroy(&resource->devices);
     free_cpumask_var(resource->cpu_mask);
     kfree(resource->name);
     memset(resource, 0xf2, sizeof(*resource));
     kfree(resource);
 }
 
 void drbd_free_resource(struct drbd_resource *resource)
 {
     struct drbd_connection *connection, *tmp;
 
     for_each_connection_safe(connection, tmp, resource) {
         list_del(&connection->connections);
         drbd_debugfs_connection_cleanup(connection);
         kref_put(&connection->kref, drbd_destroy_connection);
     }
     drbd_debugfs_resource_cleanup(resource);
     kref_put(&resource->kref, drbd_destroy_resource);
 }
 
 static void drbd_cleanup(void)
 {
     unsigned int i;
     struct drbd_device *device;
     struct drbd_resource *resource, *tmp;
 
     /* first remove proc,
      * drbdsetup uses it's presence to detect
      * whether DRBD is loaded.
      * If we would get stuck in proc removal,
      * but have netlink already deregistered,
      * some drbdsetup commands may wait forever
      * for an answer.
      */
     if (drbd_proc)
         remove_proc_entry("drbd", NULL);
 
     if (retry.wq)
         destroy_workqueue(retry.wq);
 
     drbd_genl_unregister();
 
     idr_for_each_entry(&drbd_devices, device, i)
         drbd_delete_device(device);
 
     /* not _rcu since, no other updater anymore. Genl already unregistered */
     for_each_resource_safe(resource, tmp, &drbd_resources) {
         list_del(&resource->resources);
         drbd_free_resource(resource);
     }
 
     drbd_debugfs_cleanup();
 
     drbd_destroy_mempools();
     unregister_blkdev(DRBD_MAJOR, "drbd");
 
     idr_destroy(&drbd_devices);
 
     pr_info("module cleanup done.\n");
 }
 
 static void drbd_init_workqueue(struct drbd_work_queue* wq)
 {
     spin_lock_init(&wq->q_lock);
     INIT_LIST_HEAD(&wq->q);
     init_waitqueue_head(&wq->q_wait);
 }
 
 struct completion_work {
     struct drbd_work w;
     struct completion done;
 };
 
 static int w_complete(struct drbd_work *w, int cancel)
 {
     struct completion_work *completion_work =
         container_of(w, struct completion_work, w);
 
     complete(&completion_work->done);
     return 0;
 }
 
 void drbd_flush_workqueue(struct drbd_work_queue *work_queue)
 {
     struct completion_work completion_work;
 
     completion_work.w.cb = w_complete;
     init_completion(&completion_work.done);
     drbd_queue_work(work_queue, &completion_work.w);
     wait_for_completion(&completion_work.done);
 }
 
 struct drbd_resource *drbd_find_resource(const char *name)
 {
     struct drbd_resource *resource;
 
     if (!name || !name[0])
         return NULL;
 
     rcu_read_lock();
     for_each_resource_rcu(resource, &drbd_resources) {
         if (!strcmp(resource->name, name)) {
             kref_get(&resource->kref);
             goto found;
         }
     }
     resource = NULL;
 found:
     rcu_read_unlock();
     return resource;
 }
 
 struct drbd_connection *conn_get_by_addrs(void *my_addr, int my_addr_len,
                      void *peer_addr, int peer_addr_len)
 {
     struct drbd_resource *resource;
     struct drbd_connection *connection;
 
     rcu_read_lock();
     for_each_resource_rcu(resource, &drbd_resources) {
         for_each_connection_rcu(connection, resource) {
             if (connection->my_addr_len == my_addr_len &&
                 connection->peer_addr_len == peer_addr_len &&
                 !memcmp(&connection->my_addr, my_addr, my_addr_len) &&
                 !memcmp(&connection->peer_addr, peer_addr, peer_addr_len)) {
                 kref_get(&connection->kref);
                 goto found;
             }
         }
     }
     connection = NULL;
 found:
     rcu_read_unlock();
     return connection;
 }
 
 static int drbd_alloc_socket(struct drbd_socket *socket)
 {
     socket->rbuf = (void *) __get_free_page(GFP_KERNEL);
     if (!socket->rbuf)
         return -ENOMEM;
     socket->sbuf = (void *) __get_free_page(GFP_KERNEL);
     if (!socket->sbuf)
         return -ENOMEM;
     return 0;
 }
 
 static void drbd_free_socket(struct drbd_socket *socket)
 {
     free_page((unsigned long) socket->sbuf);
     free_page((unsigned long) socket->rbuf);
 }
 
 void conn_free_crypto(struct drbd_connection *connection)
 {
     drbd_free_sock(connection);
 
     crypto_free_shash(connection->csums_tfm);
     crypto_free_shash(connection->verify_tfm);
     crypto_free_shash(connection->cram_hmac_tfm);
     crypto_free_shash(connection->integrity_tfm);
     crypto_free_shash(connection->peer_integrity_tfm);
     kfree(connection->int_dig_in);
     kfree(connection->int_dig_vv);
 
     connection->csums_tfm = NULL;
     connection->verify_tfm = NULL;
     connection->cram_hmac_tfm = NULL;
     connection->integrity_tfm = NULL;
     connection->peer_integrity_tfm = NULL;
     connection->int_dig_in = NULL;
     connection->int_dig_vv = NULL;
 }
 
 int set_resource_options(struct drbd_resource *resource, struct res_opts *res_opts)
 {
     struct drbd_connection *connection;
     cpumask_var_t new_cpu_mask;
     int err;
 
     if (!zalloc_cpumask_var(&new_cpu_mask, GFP_KERNEL))
         return -ENOMEM;
 
     /* silently ignore cpu mask on UP kernel */
     if (nr_cpu_ids > 1 && res_opts->cpu_mask[0] != 0) {
         err = bitmap_parse(res_opts->cpu_mask, DRBD_CPU_MASK_SIZE,
                    cpumask_bits(new_cpu_mask), nr_cpu_ids);
         if (err == -EOVERFLOW) {
             /* So what. mask it out. */
             cpumask_var_t tmp_cpu_mask;
             if (zalloc_cpumask_var(&tmp_cpu_mask, GFP_KERNEL)) {
                 cpumask_setall(tmp_cpu_mask);
                 cpumask_and(new_cpu_mask, new_cpu_mask, tmp_cpu_mask);
                 drbd_warn(resource, "Overflow in bitmap_parse(%.12s%s), truncating to %u bits\n",
                     res_opts->cpu_mask,
                     strlen(res_opts->cpu_mask) > 12 ? "..." : "",
                     nr_cpu_ids);
                 free_cpumask_var(tmp_cpu_mask);
                 err = 0;
             }
         }
         if (err) {
             drbd_warn(resource, "bitmap_parse() failed with %d\n", err);
             /* retcode = ERR_CPU_MASK_PARSE; */
             goto fail;
         }
     }
     resource->res_opts = *res_opts;
     if (cpumask_empty(new_cpu_mask))
         drbd_calc_cpu_mask(&new_cpu_mask);
     if (!cpumask_equal(resource->cpu_mask, new_cpu_mask)) {
         cpumask_copy(resource->cpu_mask, new_cpu_mask);
         for_each_connection_rcu(connection, resource) {
             connection->receiver.reset_cpu_mask = 1;
             connection->ack_receiver.reset_cpu_mask = 1;
             connection->worker.reset_cpu_mask = 1;
         }
     }
     err = 0;
 
 fail:
     free_cpumask_var(new_cpu_mask);
     return err;
 
 }
 
 struct drbd_resource *drbd_create_resource(const char *name)
 {
     struct drbd_resource *resource;
 
     resource = kzalloc(sizeof(struct drbd_resource), GFP_KERNEL);
     if (!resource)
         goto fail;
     resource->name = kstrdup(name, GFP_KERNEL);
     if (!resource->name)
         goto fail_free_resource;
     if (!zalloc_cpumask_var(&resource->cpu_mask, GFP_KERNEL))
         goto fail_free_name;
     kref_init(&resource->kref);
     idr_init(&resource->devices);
     INIT_LIST_HEAD(&resource->connections);
     resource->write_ordering = WO_BDEV_FLUSH;
     list_add_tail_rcu(&resource->resources, &drbd_resources);
     mutex_init(&resource->conf_update);
     mutex_init(&resource->adm_mutex);
     spin_lock_init(&resource->req_lock);
     drbd_debugfs_resource_add(resource);
     return resource;
 
 fail_free_name:
     kfree(resource->name);
 fail_free_resource:
     kfree(resource);
 fail:
     return NULL;
 }
 
 /* caller must be under adm_mutex */
 struct drbd_connection *conn_create(const char *name, struct res_opts *res_opts)
 {
     struct drbd_resource *resource;
     struct drbd_connection *connection;
 
     connection = kzalloc(sizeof(struct drbd_connection), GFP_KERNEL);
     if (!connection)
         return NULL;
 
     if (drbd_alloc_socket(&connection->data))
         goto fail;
     if (drbd_alloc_socket(&connection->meta))
         goto fail;
 
     connection->current_epoch = kzalloc(sizeof(struct drbd_epoch), GFP_KERNEL);
     if (!connection->current_epoch)
         goto fail;
 
     INIT_LIST_HEAD(&connection->transfer_log);
 
     INIT_LIST_HEAD(&connection->current_epoch->list);
     connection->epochs = 1;
     spin_lock_init(&connection->epoch_lock);
 
     connection->send.seen_any_write_yet = false;
     connection->send.current_epoch_nr = 0;
     connection->send.current_epoch_writes = 0;
 
     resource = drbd_create_resource(name);
     if (!resource)
         goto fail;
 
     connection->cstate = C_STANDALONE;
     mutex_init(&connection->cstate_mutex);
     init_waitqueue_head(&connection->ping_wait);
     idr_init(&connection->peer_devices);
 
     drbd_init_workqueue(&connection->sender_work);
     mutex_init(&connection->data.mutex);
     mutex_init(&connection->meta.mutex);
 
     drbd_thread_init(resource, &connection->receiver, drbd_receiver, "receiver");
     connection->receiver.connection = connection;
     drbd_thread_init(resource, &connection->worker, drbd_worker, "worker");
     connection->worker.connection = connection;
     drbd_thread_init(resource, &connection->ack_receiver, drbd_ack_receiver, "ack_recv");
     connection->ack_receiver.connection = connection;
 
     kref_init(&connection->kref);
 
     connection->resource = resource;
 
     if (set_resource_options(resource, res_opts))
         goto fail_resource;
 
     kref_get(&resource->kref);
     list_add_tail_rcu(&connection->connections, &resource->connections);
     drbd_debugfs_connection_add(connection);
     return connection;
 
 fail_resource:
     list_del(&resource->resources);
     drbd_free_resource(resource);
 fail:
     kfree(connection->current_epoch);
     drbd_free_socket(&connection->meta);
     drbd_free_socket(&connection->data);
     kfree(connection);
     return NULL;
 }
 
 void drbd_destroy_connection(struct kref *kref)
 {
     struct drbd_connection *connection = container_of(kref, struct drbd_connection, kref);
     struct drbd_resource *resource = connection->resource;
 
     if (atomic_read(&connection->current_epoch->epoch_size) !=  0)
         drbd_err(connection, "epoch_size:%d\n", atomic_read(&connection->current_epoch->epoch_size));
     kfree(connection->current_epoch);
 
     idr_destroy(&connection->peer_devices);
 
     drbd_free_socket(&connection->meta);
     drbd_free_socket(&connection->data);
     kfree(connection->int_dig_in);
     kfree(connection->int_dig_vv);
     memset(connection, 0xfc, sizeof(*connection));
     kfree(connection);
     kref_put(&resource->kref, drbd_destroy_resource);
 }
 
 static int init_submitter(struct drbd_device *device)
 {
     /* opencoded create_singlethread_workqueue(),
      * to be able to say "drbd%d", ..., minor */
     device->submit.wq =
         alloc_ordered_workqueue("drbd%u_submit", WQ_MEM_RECLAIM, device->minor);
     if (!device->submit.wq)
         return -ENOMEM;
 
     INIT_WORK(&device->submit.worker, do_submit);
     INIT_LIST_HEAD(&device->submit.writes);
     return 0;
 }
 
 enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsigned int minor)
 {
     struct drbd_resource *resource = adm_ctx->resource;
     struct drbd_connection *connection;
     struct drbd_device *device;
     struct drbd_peer_device *peer_device, *tmp_peer_device;
     struct gendisk *disk;
     int id;
     int vnr = adm_ctx->volume;
     enum drbd_ret_code err = ERR_NOMEM;
 
     device = minor_to_device(minor);
     if (device)
         return ERR_MINOR_OR_VOLUME_EXISTS;
 
     /* GFP_KERNEL, we are outside of all write-out paths */
     device = kzalloc(sizeof(struct drbd_device), GFP_KERNEL);
     if (!device)
         return ERR_NOMEM;
     kref_init(&device->kref);
 
     kref_get(&resource->kref);
     device->resource = resource;
     device->minor = minor;
     device->vnr = vnr;
 
     drbd_init_set_defaults(device);
 
     disk = blk_alloc_disk(NUMA_NO_NODE);
     if (!disk)
         goto out_no_disk;
 
     device->vdisk = disk;
     device->rq_queue = disk->queue;
 
     set_disk_ro(disk, true);
 
     disk->major = DRBD_MAJOR;
     disk->first_minor = minor;
     disk->minors = 1;
     disk->fops = &drbd_ops;
     disk->flags |= GENHD_FL_NO_PART;
     sprintf(disk->disk_name, "drbd%d", minor);
     disk->private_data = device;
 
     blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, disk->queue);
     blk_queue_write_cache(disk->queue, true, true);
     /* Setting the max_hw_sectors to an odd value of 8kibyte here
        This triggers a max_bio_size message upon first attach or connect */
     blk_queue_max_hw_sectors(disk->queue, DRBD_MAX_BIO_SIZE_SAFE >> 8);
 
     device->md_io.page = alloc_page(GFP_KERNEL);
     if (!device->md_io.page)
         goto out_no_io_page;
 
     if (drbd_bm_init(device))
         goto out_no_bitmap;
     device->read_requests = RB_ROOT;
     device->write_requests = RB_ROOT;
 
     id = idr_alloc(&drbd_devices, device, minor, minor + 1, GFP_KERNEL);
     if (id < 0) {
         if (id == -ENOSPC)
             err = ERR_MINOR_OR_VOLUME_EXISTS;
         goto out_no_minor_idr;
     }
     kref_get(&device->kref);
 
     id = idr_alloc(&resource->devices, device, vnr, vnr + 1, GFP_KERNEL);
     if (id < 0) {
         if (id == -ENOSPC)
             err = ERR_MINOR_OR_VOLUME_EXISTS;
         goto out_idr_remove_minor;
     }
     kref_get(&device->kref);
 
     INIT_LIST_HEAD(&device->peer_devices);
     INIT_LIST_HEAD(&device->pending_bitmap_io);
     for_each_connection(connection, resource) {
         peer_device = kzalloc(sizeof(struct drbd_peer_device), GFP_KERNEL);
         if (!peer_device)
             goto out_idr_remove_from_resource;
         peer_device->connection = connection;
         peer_device->device = device;
 
         list_add(&peer_device->peer_devices, &device->peer_devices);
         kref_get(&device->kref);
 
         id = idr_alloc(&connection->peer_devices, peer_device, vnr, vnr + 1, GFP_KERNEL);
         if (id < 0) {
             if (id == -ENOSPC)
                 err = ERR_INVALID_REQUEST;
             goto out_idr_remove_from_resource;
         }
         kref_get(&connection->kref);
         INIT_WORK(&peer_device->send_acks_work, drbd_send_acks_wf);
     }
 
     if (init_submitter(device)) {
         err = ERR_NOMEM;
         goto out_idr_remove_from_resource;
     }
 
     err = add_disk(disk);
     if (err)
         goto out_idr_remove_from_resource;
 
     /* inherit the connection state */
     device->state.conn = first_connection(resource)->cstate;
     if (device->state.conn == C_WF_REPORT_PARAMS) {
         for_each_peer_device(peer_device, device)
             drbd_connected(peer_device);
     }
     /* move to create_peer_device() */
     for_each_peer_device(peer_device, device)
         drbd_debugfs_peer_device_add(peer_device);
     drbd_debugfs_device_add(device);
     return NO_ERROR;
 
 out_idr_remove_from_resource:
     for_each_connection(connection, resource) {
         peer_device = idr_remove(&connection->peer_devices, vnr);
         if (peer_device)
             kref_put(&connection->kref, drbd_destroy_connection);
     }
     for_each_peer_device_safe(peer_device, tmp_peer_device, device) {
         list_del(&peer_device->peer_devices);
         kfree(peer_device);
     }
     idr_remove(&resource->devices, vnr);
 out_idr_remove_minor:
     idr_remove(&drbd_devices, minor);
     synchronize_rcu();
 out_no_minor_idr:
     drbd_bm_cleanup(device);
 out_no_bitmap:
     __free_page(device->md_io.page);
 out_no_io_page:
     put_disk(disk);
 out_no_disk:
     kref_put(&resource->kref, drbd_destroy_resource);
     kfree(device);
     return err;
 }
 
 void drbd_delete_device(struct drbd_device *device)
 {
     struct drbd_resource *resource = device->resource;
     struct drbd_connection *connection;
     struct drbd_peer_device *peer_device;
 
     /* move to free_peer_device() */
     for_each_peer_device(peer_device, device)
         drbd_debugfs_peer_device_cleanup(peer_device);
     drbd_debugfs_device_cleanup(device);
     for_each_connection(connection, resource) {
         idr_remove(&connection->peer_devices, device->vnr);
         kref_put(&device->kref, drbd_destroy_device);
     }
     idr_remove(&resource->devices, device->vnr);
     kref_put(&device->kref, drbd_destroy_device);
     idr_remove(&drbd_devices, device_to_minor(device));
     kref_put(&device->kref, drbd_destroy_device);
     del_gendisk(device->vdisk);
     synchronize_rcu();
     kref_put(&device->kref, drbd_destroy_device);
 }
 
 static int __init drbd_init(void)
 {
     int err;
 
     if (drbd_minor_count < DRBD_MINOR_COUNT_MIN || drbd_minor_count > DRBD_MINOR_COUNT_MAX) {
         pr_err("invalid minor_count (%d)\n", drbd_minor_count);
 #ifdef MODULE
         return -EINVAL;
 #else
         drbd_minor_count = DRBD_MINOR_COUNT_DEF;
 #endif
     }
 
     err = register_blkdev(DRBD_MAJOR, "drbd");
     if (err) {
         pr_err("unable to register block device major %d\n",
                DRBD_MAJOR);
         return err;
     }
 
     /*
      * allocate all necessary structs
      */
     init_waitqueue_head(&drbd_pp_wait);
 
     drbd_proc = NULL; /* play safe for drbd_cleanup */
     idr_init(&drbd_devices);
 
     mutex_init(&resources_mutex);
     INIT_LIST_HEAD(&drbd_resources);
 
     err = drbd_genl_register();
     if (err) {
         pr_err("unable to register generic netlink family\n");
         goto fail;
     }
 
     err = drbd_create_mempools();
     if (err)
         goto fail;
 
     err = -ENOMEM;
     drbd_proc = proc_create_single("drbd", S_IFREG | 0444 , NULL, drbd_seq_show);
     if (!drbd_proc) {
         pr_err("unable to register proc file\n");
         goto fail;
     }
 
     retry.wq = create_singlethread_workqueue("drbd-reissue");
     if (!retry.wq) {
         pr_err("unable to create retry workqueue\n");
         goto fail;
     }
     INIT_WORK(&retry.worker, do_retry);
     spin_lock_init(&retry.lock);
     INIT_LIST_HEAD(&retry.writes);
 
     drbd_debugfs_init();
 
     pr_info("initialized. "
            "Version: " REL_VERSION " (api:%d/proto:%d-%d)\n",
            API_VERSION, PRO_VERSION_MIN, PRO_VERSION_MAX);
     pr_info("%s\n", drbd_buildtag());
     pr_info("registered as block device major %d\n", DRBD_MAJOR);
     return 0; /* Success! */
 
 fail:
     drbd_cleanup();
     if (err == -ENOMEM)
         pr_err("ran out of memory\n");
     else
         pr_err("initialization failure\n");
     return err;
 }
 
 static void drbd_free_one_sock(struct drbd_socket *ds)
 {
     struct socket *s;
     mutex_lock(&ds->mutex);
     s = ds->socket;
     ds->socket = NULL;
     mutex_unlock(&ds->mutex);
     if (s) {
         /* so debugfs does not need to mutex_lock() */
         synchronize_rcu();
         kernel_sock_shutdown(s, SHUT_RDWR);
         sock_release(s);
     }
 }
 
 void drbd_free_sock(struct drbd_connection *connection)
 {
     if (connection->data.socket)
         drbd_free_one_sock(&connection->data);
     if (connection->meta.socket)
         drbd_free_one_sock(&connection->meta);
 }
 
 /* meta data management */
 
 void conn_md_sync(struct drbd_connection *connection)
 {
     struct drbd_peer_device *peer_device;
     int vnr;
 
     rcu_read_lock();
     idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
         struct drbd_device *device = peer_device->device;
 
         kref_get(&device->kref);
         rcu_read_unlock();
         drbd_md_sync(device);
         kref_put(&device->kref, drbd_destroy_device);
         rcu_read_lock();
     }
     rcu_read_unlock();
 }
 
 /* aligned 4kByte */
 struct meta_data_on_disk {
     u64 la_size_sect;      /* last agreed size. */
     u64 uuid[UI_SIZE];   /* UUIDs. */
     u64 device_uuid;
     u64 reserved_u64_1;
     u32 flags;             /* MDF */
     u32 magic;
     u32 md_size_sect;
     u32 al_offset;         /* offset to this block */
     u32 al_nr_extents;     /* important for restoring the AL (userspace) */
           /* `-- act_log->nr_elements <-- ldev->dc.al_extents */
     u32 bm_offset;         /* offset to the bitmap, from here */
     u32 bm_bytes_per_bit;  /* BM_BLOCK_SIZE */
     u32 la_peer_max_bio_size;   /* last peer max_bio_size */
 
     /* see al_tr_number_to_on_disk_sector() */
     u32 al_stripes;
     u32 al_stripe_size_4k;
 
     u8 reserved_u8[4096 - (7*8 + 10*4)];
 } __packed;
 
 
 
 void drbd_md_write(struct drbd_device *device, void *b)
 {
     struct meta_data_on_disk *buffer = b;
     sector_t sector;
     int i;
 
     memset(buffer, 0, sizeof(*buffer));
 
     buffer->la_size_sect = cpu_to_be64(get_capacity(device->vdisk));
     for (i = UI_CURRENT; i < UI_SIZE; i++)
         buffer->uuid[i] = cpu_to_be64(device->ldev->md.uuid[i]);
     buffer->flags = cpu_to_be32(device->ldev->md.flags);
     buffer->magic = cpu_to_be32(DRBD_MD_MAGIC_84_UNCLEAN);
 
     buffer->md_size_sect  = cpu_to_be32(device->ldev->md.md_size_sect);
     buffer->al_offset     = cpu_to_be32(device->ldev->md.al_offset);
     buffer->al_nr_extents = cpu_to_be32(device->act_log->nr_elements);
     buffer->bm_bytes_per_bit = cpu_to_be32(BM_BLOCK_SIZE);
     buffer->device_uuid = cpu_to_be64(device->ldev->md.device_uuid);
 
     buffer->bm_offset = cpu_to_be32(device->ldev->md.bm_offset);
     buffer->la_peer_max_bio_size = cpu_to_be32(device->peer_max_bio_size);
 
     buffer->al_stripes = cpu_to_be32(device->ldev->md.al_stripes);
     buffer->al_stripe_size_4k = cpu_to_be32(device->ldev->md.al_stripe_size_4k);
 
     D_ASSERT(device, drbd_md_ss(device->ldev) == device->ldev->md.md_offset);
     sector = device->ldev->md.md_offset;
 
     if (drbd_md_sync_page_io(device, device->ldev, sector, REQ_OP_WRITE)) {
         /* this was a try anyways ... */
         drbd_err(device, "meta data update failed!\n");
         drbd_chk_io_error(device, 1, DRBD_META_IO_ERROR);
     }
 }
 
 /**
  * drbd_md_sync() - Writes the meta data super block if the MD_DIRTY flag bit is set
  * @device: DRBD device.
  */
 void drbd_md_sync(struct drbd_device *device)
 {
     struct meta_data_on_disk *buffer;
 
     /* Don't accidentally change the DRBD meta data layout. */
     BUILD_BUG_ON(UI_SIZE != 4);
     BUILD_BUG_ON(sizeof(struct meta_data_on_disk) != 4096);
 
     del_timer(&device->md_sync_timer);
     /* timer may be rearmed by drbd_md_mark_dirty() now. */
     if (!test_and_clear_bit(MD_DIRTY, &device->flags))
         return;
 
     /* We use here D_FAILED and not D_ATTACHING because we try to write
      * metadata even if we detach due to a disk failure! */
     if (!get_ldev_if_state(device, D_FAILED))
         return;
 
     buffer = drbd_md_get_buffer(device, __func__);
     if (!buffer)
         goto out;
 
     drbd_md_write(device, buffer);
 
     /* Update device->ldev->md.la_size_sect,
      * since we updated it on metadata. */
     device->ldev->md.la_size_sect = get_capacity(device->vdisk);
 
     drbd_md_put_buffer(device);
 out:
     put_ldev(device);
 }
 
 static int check_activity_log_stripe_size(struct drbd_device *device,
         struct meta_data_on_disk *on_disk,
         struct drbd_md *in_core)
 {
     u32 al_stripes = be32_to_cpu(on_disk->al_stripes);
     u32 al_stripe_size_4k = be32_to_cpu(on_disk->al_stripe_size_4k);
     u64 al_size_4k;
 
     /* both not set: default to old fixed size activity log */
     if (al_stripes == 0 && al_stripe_size_4k == 0) {
         al_stripes = 1;
         al_stripe_size_4k = MD_32kB_SECT/8;
     }
 
     /* some paranoia plausibility checks */
 
     /* we need both values to be set */
     if (al_stripes == 0 || al_stripe_size_4k == 0)
         goto err;
 
     al_size_4k = (u64)al_stripes * al_stripe_size_4k;
 
     /* Upper limit of activity log area, to avoid potential overflow
      * problems in al_tr_number_to_on_disk_sector(). As right now, more
      * than 72 * 4k blocks total only increases the amount of history,
      * limiting this arbitrarily to 16 GB is not a real limitation ;-)  */
     if (al_size_4k > (16 * 1024 * 1024/4))
         goto err;
 
     /* Lower limit: we need at least 8 transaction slots (32kB)
      * to not break existing setups */
     if (al_size_4k < MD_32kB_SECT/8)
         goto err;
 
     in_core->al_stripe_size_4k = al_stripe_size_4k;
     in_core->al_stripes = al_stripes;
     in_core->al_size_4k = al_size_4k;
 
     return 0;
 err:
     drbd_err(device, "invalid activity log striping: al_stripes=%u, al_stripe_size_4k=%u\n",
             al_stripes, al_stripe_size_4k);
     return -EINVAL;
 }
 
 static int check_offsets_and_sizes(struct drbd_device *device, struct drbd_backing_dev *bdev)
 {
     sector_t capacity = drbd_get_capacity(bdev->md_bdev);
     struct drbd_md *in_core = &bdev->md;
     s32 on_disk_al_sect;
     s32 on_disk_bm_sect;
 
     /* The on-disk size of the activity log, calculated from offsets, and
      * the size of the activity log calculated from the stripe settings,
      * should match.
      * Though we could relax this a bit: it is ok, if the striped activity log
      * fits in the available on-disk activity log size.
      * Right now, that would break how resize is implemented.
      * TODO: make drbd_determine_dev_size() (and the drbdmeta tool) aware
      * of possible unused padding space in the on disk layout. */
     if (in_core->al_offset < 0) {
         if (in_core->bm_offset > in_core->al_offset)
             goto err;
         on_disk_al_sect = -in_core->al_offset;
         on_disk_bm_sect = in_core->al_offset - in_core->bm_offset;
     } else {
         if (in_core->al_offset != MD_4kB_SECT)
             goto err;
         if (in_core->bm_offset < in_core->al_offset + in_core->al_size_4k * MD_4kB_SECT)
             goto err;
 
         on_disk_al_sect = in_core->bm_offset - MD_4kB_SECT;
         on_disk_bm_sect = in_core->md_size_sect - in_core->bm_offset;
     }
 
     /* old fixed size meta data is exactly that: fixed. */
     if (in_core->meta_dev_idx >= 0) {
         if (in_core->md_size_sect != MD_128MB_SECT
         ||  in_core->al_offset != MD_4kB_SECT
         ||  in_core->bm_offset != MD_4kB_SECT + MD_32kB_SECT
         ||  in_core->al_stripes != 1
         ||  in_core->al_stripe_size_4k != MD_32kB_SECT/8)
             goto err;
     }
 
     if (capacity < in_core->md_size_sect)
         goto err;
     if (capacity - in_core->md_size_sect < drbd_md_first_sector(bdev))
         goto err;
 
     /* should be aligned, and at least 32k */
     if ((on_disk_al_sect & 7) || (on_disk_al_sect < MD_32kB_SECT))
         goto err;
 
     /* should fit (for now: exactly) into the available on-disk space;
      * overflow prevention is in check_activity_log_stripe_size() above. */
     if (on_disk_al_sect != in_core->al_size_4k * MD_4kB_SECT)
         goto err;
 
     /* again, should be aligned */
     if (in_core->bm_offset & 7)
         goto err;
 
     /* FIXME check for device grow with flex external meta data? */
 
     /* can the available bitmap space cover the last agreed device size? */
     if (on_disk_bm_sect < (in_core->la_size_sect+7)/MD_4kB_SECT/8/512)
         goto err;
 
     return 0;
 
 err:
     drbd_err(device, "meta data offsets don't make sense: idx=%d "
             "al_s=%u, al_sz4k=%u, al_offset=%d, bm_offset=%d, "
             "md_size_sect=%u, la_size=%llu, md_capacity=%llu\n",
             in_core->meta_dev_idx,
             in_core->al_stripes, in_core->al_stripe_size_4k,
             in_core->al_offset, in_core->bm_offset, in_core->md_size_sect,
             (unsigned long long)in_core->la_size_sect,
             (unsigned long long)capacity);
 
     return -EINVAL;
 }
 
 
 /**
  * drbd_md_read() - Reads in the meta data super block
  * @device: DRBD device.
  * @bdev:   Device from which the meta data should be read in.
  *
  * Return NO_ERROR on success, and an enum drbd_ret_code in case
  * something goes wrong.
  *
  * Called exactly once during drbd_adm_attach(), while still being D_DISKLESS,
  * even before @bdev is assigned to @device->ldev.
  */
 int drbd_md_read(struct drbd_device *device, struct drbd_backing_dev *bdev)
 {
     struct meta_data_on_disk *buffer;
     u32 magic, flags;
     int i, rv = NO_ERROR;
 
     if (device->state.disk != D_DISKLESS)
         return ERR_DISK_CONFIGURED;
 
     buffer = drbd_md_get_buffer(device, __func__);
     if (!buffer)
         return ERR_NOMEM;
 
     /* First, figure out where our meta data superblock is located,
      * and read it. */
     bdev->md.meta_dev_idx = bdev->disk_conf->meta_dev_idx;
     bdev->md.md_offset = drbd_md_ss(bdev);
     /* Even for (flexible or indexed) external meta data,
      * initially restrict us to the 4k superblock for now.
      * Affects the paranoia out-of-range access check in drbd_md_sync_page_io(). */
     bdev->md.md_size_sect = 8;
 
     if (drbd_md_sync_page_io(device, bdev, bdev->md.md_offset,
                  REQ_OP_READ)) {
         /* NOTE: can't do normal error processing here as this is
            called BEFORE disk is attached */
         drbd_err(device, "Error while reading metadata.\n");
         rv = ERR_IO_MD_DISK;
         goto err;
     }
 
     magic = be32_to_cpu(buffer->magic);
     flags = be32_to_cpu(buffer->flags);
     if (magic == DRBD_MD_MAGIC_84_UNCLEAN ||
         (magic == DRBD_MD_MAGIC_08 && !(flags & MDF_AL_CLEAN))) {
             /* btw: that's Activity Log clean, not "all" clean. */
         drbd_err(device, "Found unclean meta data. Did you \"drbdadm apply-al\"?\n");
         rv = ERR_MD_UNCLEAN;
         goto err;
     }
 
     rv = ERR_MD_INVALID;
     if (magic != DRBD_MD_MAGIC_08) {
         if (magic == DRBD_MD_MAGIC_07)
             drbd_err(device, "Found old (0.7) meta data magic. Did you \"drbdadm create-md\"?\n");
         else
             drbd_err(device, "Meta data magic not found. Did you \"drbdadm create-md\"?\n");
         goto err;
     }
 
     if (be32_to_cpu(buffer->bm_bytes_per_bit) != BM_BLOCK_SIZE) {
         drbd_err(device, "unexpected bm_bytes_per_bit: %u (expected %u)\n",
             be32_to_cpu(buffer->bm_bytes_per_bit), BM_BLOCK_SIZE);
         goto err;
     }
 
 
     /* convert to in_core endian */
     bdev->md.la_size_sect = be64_to_cpu(buffer->la_size_sect);
     for (i = UI_CURRENT; i < UI_SIZE; i++)
         bdev->md.uuid[i] = be64_to_cpu(buffer->uuid[i]);
     bdev->md.flags = be32_to_cpu(buffer->flags);
     bdev->md.device_uuid = be64_to_cpu(buffer->device_uuid);
 
     bdev->md.md_size_sect = be32_to_cpu(buffer->md_size_sect);
     bdev->md.al_offset = be32_to_cpu(buffer->al_offset);
     bdev->md.bm_offset = be32_to_cpu(buffer->bm_offset);
 
     if (check_activity_log_stripe_size(device, buffer, &bdev->md))
         goto err;
     if (check_offsets_and_sizes(device, bdev))
         goto err;
 
     if (be32_to_cpu(buffer->bm_offset) != bdev->md.bm_offset) {
         drbd_err(device, "unexpected bm_offset: %d (expected %d)\n",
             be32_to_cpu(buffer->bm_offset), bdev->md.bm_offset);
         goto err;
     }
     if (be32_to_cpu(buffer->md_size_sect) != bdev->md.md_size_sect) {
         drbd_err(device, "unexpected md_size: %u (expected %u)\n",
             be32_to_cpu(buffer->md_size_sect), bdev->md.md_size_sect);
         goto err;
     }
 
     rv = NO_ERROR;
 
     spin_lock_irq(&device->resource->req_lock);
     if (device->state.conn < C_CONNECTED) {
         unsigned int peer;
         peer = be32_to_cpu(buffer->la_peer_max_bio_size);
         peer = max(peer, DRBD_MAX_BIO_SIZE_SAFE);
         device->peer_max_bio_size = peer;
     }
     spin_unlock_irq(&device->resource->req_lock);
 
  err:
     drbd_md_put_buffer(device);
 
     return rv;
 }
 
 /**
  * drbd_md_mark_dirty() - Mark meta data super block as dirty
  * @device: DRBD device.
  *
  * Call this function if you change anything that should be written to
  * the meta-data super block. This function sets MD_DIRTY, and starts a
  * timer that ensures that within five seconds you have to call drbd_md_sync().
  */
 void drbd_md_mark_dirty(struct drbd_device *device)
 {
     if (!test_and_set_bit(MD_DIRTY, &device->flags))
         mod_timer(&device->md_sync_timer, jiffies + 5*HZ);
 }
 
 void drbd_uuid_move_history(struct drbd_device *device) __must_hold(local)
 {
     int i;
 
     for (i = UI_HISTORY_START; i < UI_HISTORY_END; i++)
         device->ldev->md.uuid[i+1] = device->ldev->md.uuid[i];
 }
 
 void __drbd_uuid_set(struct drbd_device *device, int idx, u64 val) __must_hold(local)
 {
     if (idx == UI_CURRENT) {
         if (device->state.role == R_PRIMARY)
             val |= 1;
         else
             val &= ~((u64)1);
 
         drbd_set_ed_uuid(device, val);
     }
 
     device->ldev->md.uuid[idx] = val;
     drbd_md_mark_dirty(device);
 }
 
 void _drbd_uuid_set(struct drbd_device *device, int idx, u64 val) __must_hold(local)
 {
     unsigned long flags;
     spin_lock_irqsave(&device->ldev->md.uuid_lock, flags);
     __drbd_uuid_set(device, idx, val);
     spin_unlock_irqrestore(&device->ldev->md.uuid_lock, flags);
 }
 
 void drbd_uuid_set(struct drbd_device *device, int idx, u64 val) __must_hold(local)
 {
     unsigned long flags;
     spin_lock_irqsave(&device->ldev->md.uuid_lock, flags);
     if (device->ldev->md.uuid[idx]) {
         drbd_uuid_move_history(device);
         device->ldev->md.uuid[UI_HISTORY_START] = device->ldev->md.uuid[idx];
     }
     __drbd_uuid_set(device, idx, val);
     spin_unlock_irqrestore(&device->ldev->md.uuid_lock, flags);
 }
 
 /**
  * drbd_uuid_new_current() - Creates a new current UUID
  * @device: DRBD device.
  *
  * Creates a new current UUID, and rotates the old current UUID into
  * the bitmap slot. Causes an incremental resync upon next connect.
  */
 void drbd_uuid_new_current(struct drbd_device *device) __must_hold(local)
 {
     u64 val;
     unsigned long long bm_uuid;
 
     get_random_bytes(&val, sizeof(u64));
 
     spin_lock_irq(&device->ldev->md.uuid_lock);
     bm_uuid = device->ldev->md.uuid[UI_BITMAP];
 
     if (bm_uuid)
         drbd_warn(device, "bm UUID was already set: %llX\n", bm_uuid);
 
     device->ldev->md.uuid[UI_BITMAP] = device->ldev->md.uuid[UI_CURRENT];
     __drbd_uuid_set(device, UI_CURRENT, val);
     spin_unlock_irq(&device->ldev->md.uuid_lock);
 
     drbd_print_uuids(device, "new current UUID");
     /* get it to stable storage _now_ */
     drbd_md_sync(device);
 }
 
 void drbd_uuid_set_bm(struct drbd_device *device, u64 val) __must_hold(local)
 {
     unsigned long flags;
     if (device->ldev->md.uuid[UI_BITMAP] == 0 && val == 0)
         return;
 
     spin_lock_irqsave(&device->ldev->md.uuid_lock, flags);
     if (val == 0) {
         drbd_uuid_move_history(device);
         device->ldev->md.uuid[UI_HISTORY_START] = device->ldev->md.uuid[UI_BITMAP];
         device->ldev->md.uuid[UI_BITMAP] = 0;
     } else {
         unsigned long long bm_uuid = device->ldev->md.uuid[UI_BITMAP];
         if (bm_uuid)
             drbd_warn(device, "bm UUID was already set: %llX\n", bm_uuid);
 
         device->ldev->md.uuid[UI_BITMAP] = val & ~((u64)1);
     }
     spin_unlock_irqrestore(&device->ldev->md.uuid_lock, flags);
 
     drbd_md_mark_dirty(device);
 }
 
 /**
  * drbd_bmio_set_n_write() - io_fn for drbd_queue_bitmap_io() or drbd_bitmap_io()
  * @device: DRBD device.
  *
  * Sets all bits in the bitmap and writes the whole bitmap to stable storage.
  */
 int drbd_bmio_set_n_write(struct drbd_device *device) __must_hold(local)
 {
     int rv = -EIO;
 
     drbd_md_set_flag(device, MDF_FULL_SYNC);
     drbd_md_sync(device);
     drbd_bm_set_all(device);
 
     rv = drbd_bm_write(device);
 
     if (!rv) {
         drbd_md_clear_flag(device, MDF_FULL_SYNC);
         drbd_md_sync(device);
     }
 
     return rv;
 }
 
 /**
  * drbd_bmio_clear_n_write() - io_fn for drbd_queue_bitmap_io() or drbd_bitmap_io()
  * @device: DRBD device.
  *
  * Clears all bits in the bitmap and writes the whole bitmap to stable storage.
  */
 int drbd_bmio_clear_n_write(struct drbd_device *device) __must_hold(local)
 {
     drbd_resume_al(device);
     drbd_bm_clear_all(device);
     return drbd_bm_write(device);
 }
 
 static int w_bitmap_io(struct drbd_work *w, int unused)
 {
     struct drbd_device *device =
         container_of(w, struct drbd_device, bm_io_work.w);
     struct bm_io_work *work = &device->bm_io_work;
     int rv = -EIO;
 
     if (work->flags != BM_LOCKED_CHANGE_ALLOWED) {
         int cnt = atomic_read(&device->ap_bio_cnt);
         if (cnt)
             drbd_err(device, "FIXME: ap_bio_cnt %d, expected 0; queued for '%s'\n",
                     cnt, work->why);
     }
 
     if (get_ldev(device)) {
         drbd_bm_lock(device, work->why, work->flags);
         rv = work->io_fn(device);
         drbd_bm_unlock(device);
         put_ldev(device);
     }
 
     clear_bit_unlock(BITMAP_IO, &device->flags);
     wake_up(&device->misc_wait);
 
     if (work->done)
         work->done(device, rv);
 
     clear_bit(BITMAP_IO_QUEUED, &device->flags);
     work->why = NULL;
     work->flags = 0;
 
     return 0;
 }
 
 /**
  * drbd_queue_bitmap_io() - Queues an IO operation on the whole bitmap
  * @device: DRBD device.
  * @io_fn:  IO callback to be called when bitmap IO is possible
  * @done:   callback to be called after the bitmap IO was performed
  * @why:    Descriptive text of the reason for doing the IO
  * @flags:  Bitmap flags
  *
  * While IO on the bitmap happens we freeze application IO thus we ensure
  * that drbd_set_out_of_sync() can not be called. This function MAY ONLY be
  * called from worker context. It MUST NOT be used while a previous such
  * work is still pending!
  *
  * Its worker function encloses the call of io_fn() by get_ldev() and
  * put_ldev().
  */
 void drbd_queue_bitmap_io(struct drbd_device *device,
               int (*io_fn)(struct drbd_device *),
               void (*done)(struct drbd_device *, int),
               char *why, enum bm_flag flags)
 {
     D_ASSERT(device, current == first_peer_device(device)->connection->worker.task);
 
     D_ASSERT(device, !test_bit(BITMAP_IO_QUEUED, &device->flags));
     D_ASSERT(device, !test_bit(BITMAP_IO, &device->flags));
     D_ASSERT(device, list_empty(&device->bm_io_work.w.list));
     if (device->bm_io_work.why)
         drbd_err(device, "FIXME going to queue '%s' but '%s' still pending?\n",
             why, device->bm_io_work.why);
 
     device->bm_io_work.io_fn = io_fn;
     device->bm_io_work.done = done;
     device->bm_io_work.why = why;
     device->bm_io_work.flags = flags;
 
     spin_lock_irq(&device->resource->req_lock);
     set_bit(BITMAP_IO, &device->flags);
     /* don't wait for pending application IO if the caller indicates that
      * application IO does not conflict anyways. */
     if (flags == BM_LOCKED_CHANGE_ALLOWED || atomic_read(&device->ap_bio_cnt) == 0) {
         if (!test_and_set_bit(BITMAP_IO_QUEUED, &device->flags))
             drbd_queue_work(&first_peer_device(device)->connection->sender_work,
                     &device->bm_io_work.w);
     }
     spin_unlock_irq(&device->resource->req_lock);
 }
 
 /**
  * drbd_bitmap_io() -  Does an IO operation on the whole bitmap
  * @device: DRBD device.
  * @io_fn:  IO callback to be called when bitmap IO is possible
  * @why:    Descriptive text of the reason for doing the IO
  * @flags:  Bitmap flags
  *
  * freezes application IO while that the actual IO operations runs. This
  * functions MAY NOT be called from worker context.
  */
 int drbd_bitmap_io(struct drbd_device *device, int (*io_fn)(struct drbd_device *),
         char *why, enum bm_flag flags)
 {
     /* Only suspend io, if some operation is supposed to be locked out */
     const bool do_suspend_io = flags & (BM_DONT_CLEAR|BM_DONT_SET|BM_DONT_TEST);
     int rv;
 
     D_ASSERT(device, current != first_peer_device(device)->connection->worker.task);
 
     if (do_suspend_io)
         drbd_suspend_io(device);
 
     drbd_bm_lock(device, why, flags);
     rv = io_fn(device);
     drbd_bm_unlock(device);
 
     if (do_suspend_io)
         drbd_resume_io(device);
 
     return rv;
 }
 
 void drbd_md_set_flag(struct drbd_device *device, int flag) __must_hold(local)
 {
     if ((device->ldev->md.flags & flag) != flag) {
         drbd_md_mark_dirty(device);
         device->ldev->md.flags |= flag;
     }
 }
 
 void drbd_md_clear_flag(struct drbd_device *device, int flag) __must_hold(local)
 {
     if ((device->ldev->md.flags & flag) != 0) {
         drbd_md_mark_dirty(device);
         device->ldev->md.flags &= ~flag;
     }
 }
 int drbd_md_test_flag(struct drbd_backing_dev *bdev, int flag)
 {
     return (bdev->md.flags & flag) != 0;
 }
 
 static void md_sync_timer_fn(struct timer_list *t)
 {
     struct drbd_device *device = from_timer(device, t, md_sync_timer);
     drbd_device_post_work(device, MD_SYNC);
 }
 
 const char *cmdname(enum drbd_packet cmd)
 {
     /* THINK may need to become several global tables
      * when we want to support more than
      * one PRO_VERSION */
     static const char *cmdnames[] = {
 
         [P_DATA]            = "Data",
         [P_DATA_REPLY]          = "DataReply",
         [P_RS_DATA_REPLY]   = "RSDataReply",
         [P_BARRIER]         = "Barrier",
         [P_BITMAP]          = "ReportBitMap",
         [P_BECOME_SYNC_TARGET]  = "BecomeSyncTarget",
         [P_BECOME_SYNC_SOURCE]  = "BecomeSyncSource",
         [P_UNPLUG_REMOTE]   = "UnplugRemote",
         [P_DATA_REQUEST]    = "DataRequest",
         [P_RS_DATA_REQUEST]     = "RSDataRequest",
         [P_SYNC_PARAM]          = "SyncParam",
         [P_PROTOCOL]            = "ReportProtocol",
         [P_UUIDS]           = "ReportUUIDs",
         [P_SIZES]           = "ReportSizes",
         [P_STATE]           = "ReportState",
         [P_SYNC_UUID]           = "ReportSyncUUID",
         [P_AUTH_CHALLENGE]      = "AuthChallenge",
         [P_AUTH_RESPONSE]   = "AuthResponse",
         [P_STATE_CHG_REQ]       = "StateChgRequest",
         [P_PING]        = "Ping",
         [P_PING_ACK]            = "PingAck",
         [P_RECV_ACK]            = "RecvAck",
         [P_WRITE_ACK]           = "WriteAck",
         [P_RS_WRITE_ACK]    = "RSWriteAck",
         [P_SUPERSEDED]          = "Superseded",
         [P_NEG_ACK]         = "NegAck",
         [P_NEG_DREPLY]          = "NegDReply",
         [P_NEG_RS_DREPLY]   = "NegRSDReply",
         [P_BARRIER_ACK]         = "BarrierAck",
         [P_STATE_CHG_REPLY]     = "StateChgReply",
         [P_OV_REQUEST]          = "OVRequest",
         [P_OV_REPLY]            = "OVReply",
         [P_OV_RESULT]           = "OVResult",
         [P_CSUM_RS_REQUEST]     = "CsumRSRequest",
         [P_RS_IS_IN_SYNC]   = "CsumRSIsInSync",
         [P_SYNC_PARAM89]    = "SyncParam89",
         [P_COMPRESSED_BITMAP]   = "CBitmap",
         [P_DELAY_PROBE]         = "DelayProbe",
         [P_OUT_OF_SYNC]     = "OutOfSync",
         [P_RS_CANCEL]       = "RSCancel",
         [P_CONN_ST_CHG_REQ] = "conn_st_chg_req",
         [P_CONN_ST_CHG_REPLY]   = "conn_st_chg_reply",
         [P_PROTOCOL_UPDATE] = "protocol_update",
         [P_TRIM]            = "Trim",
         [P_RS_THIN_REQ]         = "rs_thin_req",
         [P_RS_DEALLOCATED]      = "rs_deallocated",
         [P_WSAME]           = "WriteSame",
         [P_ZEROES]      = "Zeroes",
 
         /* enum drbd_packet, but not commands - obsoleted flags:
          *  P_MAY_IGNORE
          *  P_MAX_OPT_CMD
          */
     };
 
     /* too big for the array: 0xfffX */
     if (cmd == P_INITIAL_META)
         return "InitialMeta";
     if (cmd == P_INITIAL_DATA)
         return "InitialData";
     if (cmd == P_CONNECTION_FEATURES)
         return "ConnectionFeatures";
     if (cmd >= ARRAY_SIZE(cmdnames))
         return "Unknown";
     return cmdnames[cmd];
 }
 
 /**
  * drbd_wait_misc  -  wait for a request to make progress
  * @device: device associated with the request
  * @i:      the struct drbd_interval embedded in struct drbd_request or
  *      struct drbd_peer_request
  */
 int drbd_wait_misc(struct drbd_device *device, struct drbd_interval *i)
 {
     struct net_conf *nc;
     DEFINE_WAIT(wait);
     long timeout;
 
     rcu_read_lock();
     nc = rcu_dereference(first_peer_device(device)->connection->net_conf);
     if (!nc) {
         rcu_read_unlock();
         return -ETIMEDOUT;
     }
     timeout = nc->ko_count ? nc->timeout * HZ / 10 * nc->ko_count : MAX_SCHEDULE_TIMEOUT;
     rcu_read_unlock();
 
     /* Indicate to wake up device->misc_wait on progress.  */
     i->waiting = true;
     prepare_to_wait(&device->misc_wait, &wait, TASK_INTERRUPTIBLE);
     spin_unlock_irq(&device->resource->req_lock);
     timeout = schedule_timeout(timeout);
     finish_wait(&device->misc_wait, &wait);
     spin_lock_irq(&device->resource->req_lock);
     if (!timeout || device->state.conn < C_CONNECTED)
         return -ETIMEDOUT;
     if (signal_pending(current))
         return -ERESTARTSYS;
     return 0;
 }
 
 void lock_all_resources(void)
 {
     struct drbd_resource *resource;
     int __maybe_unused i = 0;
 
     mutex_lock(&resources_mutex);
     local_irq_disable();
     for_each_resource(resource, &drbd_resources)
         spin_lock_nested(&resource->req_lock, i++);
 }
 
 void unlock_all_resources(void)
 {
     struct drbd_resource *resource;
 
     for_each_resource(resource, &drbd_resources)
         spin_unlock(&resource->req_lock);
     local_irq_enable();
     mutex_unlock(&resources_mutex);
 }
 
 #ifdef CONFIG_DRBD_FAULT_INJECTION
 /* Fault insertion support including random number generator shamelessly
  * stolen from kernel/rcutorture.c */
 struct fault_random_state {
     unsigned long state;
     unsigned long count;
 };
 
 #define FAULT_RANDOM_MULT 39916801  /* prime */
 #define FAULT_RANDOM_ADD    479001701 /* prime */
 #define FAULT_RANDOM_REFRESH 10000
 
 /*
  * Crude but fast random-number generator.  Uses a linear congruential
  * generator, with occasional help from get_random_bytes().
  */
 static unsigned long
 _drbd_fault_random(struct fault_random_state *rsp)
 {
     long refresh;
 
     if (!rsp->count--) {
         get_random_bytes(&refresh, sizeof(refresh));
         rsp->state += refresh;
         rsp->count = FAULT_RANDOM_REFRESH;
     }
     rsp->state = rsp->state * FAULT_RANDOM_MULT + FAULT_RANDOM_ADD;
     return swahw32(rsp->state);
 }
 
 static char *
 _drbd_fault_str(unsigned int type) {
     static char *_faults[] = {
         [DRBD_FAULT_MD_WR] = "Meta-data write",
         [DRBD_FAULT_MD_RD] = "Meta-data read",
         [DRBD_FAULT_RS_WR] = "Resync write",
         [DRBD_FAULT_RS_RD] = "Resync read",
         [DRBD_FAULT_DT_WR] = "Data write",
         [DRBD_FAULT_DT_RD] = "Data read",
         [DRBD_FAULT_DT_RA] = "Data read ahead",
         [DRBD_FAULT_BM_ALLOC] = "BM allocation",
         [DRBD_FAULT_AL_EE] = "EE allocation",
         [DRBD_FAULT_RECEIVE] = "receive data corruption",
     };
 
     return (type < DRBD_FAULT_MAX) ? _faults[type] : "**Unknown**";
 }
 
 unsigned int
 _drbd_insert_fault(struct drbd_device *device, unsigned int type)
 {
     static struct fault_random_state rrs = {0, 0};
 
     unsigned int ret = (
         (drbd_fault_devs == 0 ||
             ((1 << device_to_minor(device)) & drbd_fault_devs) != 0) &&
         (((_drbd_fault_random(&rrs) % 100) + 1) <= drbd_fault_rate));
 
     if (ret) {
         drbd_fault_count++;
 
         if (__ratelimit(&drbd_ratelimit_state))
             drbd_warn(device, "***Simulating %s failure\n",
                 _drbd_fault_str(type));
     }
 
     return ret;
 }
 #endif
 
 const char *drbd_buildtag(void)
 {
     /* DRBD built from external sources has here a reference to the
        git hash of the source code. */
 
     static char buildtag[38] = "\0uilt-in";
 
     if (buildtag[0] == 0) {
 #ifdef MODULE
         sprintf(buildtag, "srcversion: %-24s", THIS_MODULE->srcversion);
 #else
         buildtag[0] = 'b';
 #endif
     }
 
     return buildtag;
 }
 
 module_init(drbd_init)
 module_exit(drbd_cleanup)
 
 EXPORT_SYMBOL(drbd_conn_str);
 EXPORT_SYMBOL(drbd_role_str);
 EXPORT_SYMBOL(drbd_disk_str);
 EXPORT_SYMBOL(drbd_set_st_err_str);