/*
 * (C) 2001 Clemson University and The University of Chicago
 * (C) 2011 Omnibond Systems
 *
 * Changes by Acxiom Corporation to implement generic service_operation()
 * function, Copyright Acxiom Corporation, 2005.
 *
 * See COPYING in top-level directory.
 */

/*
 *  In-kernel waitqueue operations.
 */

#include "protocol.h"
#include "orangefs-kernel.h"
#include "orangefs-bufmap.h"

static int wait_for_matching_downcall(struct orangefs_kernel_op_s *, long, bool);
static void orangefs_clean_up_interrupted_operation(struct orangefs_kernel_op_s *);

/*
 * What we do in this function is to walk the list of operations that are
 * present in the request queue and mark them as purged.
 * NOTE: This is called from the device close after client-core has
 * guaranteed that no new operations could appear on the list since the
 * client-core is anyway going to exit.
 */
void purge_waiting_ops(void)
{
        struct orangefs_kernel_op_s *op;

        spin_lock(&orangefs_request_list_lock);
        list_for_each_entry(op, &orangefs_request_list, list) {
                gossip_debug(GOSSIP_WAIT_DEBUG,
                             "pvfs2-client-core: purging op tag %llu %s\n",
                             llu(op->tag),
                             get_opname_string(op));
                set_op_state_purged(op);
                gossip_debug(GOSSIP_DEV_DEBUG,
                             "%s: op:%s: op_state:%d: process:%s:\n",
                             __func__,
                             get_opname_string(op),
                             op->op_state,
                             current->comm);
        }
        spin_unlock(&orangefs_request_list_lock);
}

/*
 * submits a ORANGEFS operation and waits for it to complete
 *
 * Note op->downcall.status will contain the status of the operation (in
 * errno format), whether provided by pvfs2-client or a result of failure to
 * service the operation.  If the caller wishes to distinguish, then
 * op->state can be checked to see if it was serviced or not.
 *
 * Returns contents of op->downcall.status for convenience
 */
int service_operation(struct orangefs_kernel_op_s *op,
                      const char *op_name,
                      int flags)
{
        long timeout = MAX_SCHEDULE_TIMEOUT;
        int ret = 0;

        DEFINE_WAIT(wait_entry);

        op->upcall.tgid = current->tgid;
        op->upcall.pid = current->pid;

retry_servicing:
        op->downcall.status = 0;
        gossip_debug(GOSSIP_WAIT_DEBUG,
                     "%s: %s op:%p: process:%s: pid:%d:\n",
                     __func__,
                     op_name,
                     op,
                     current->comm,
                     current->pid);

        /*
         * If ORANGEFS_OP_NO_MUTEX was set in flags, we need to avoid
         * acquiring the request_mutex because we're servicing a
         * high priority remount operation and the request_mutex is
         * already taken.
         */
        if (!(flags & ORANGEFS_OP_NO_MUTEX)) {
                if (flags & ORANGEFS_OP_INTERRUPTIBLE)
                        ret = mutex_lock_interruptible(&orangefs_request_mutex);
                else
                        ret = mutex_lock_killable(&orangefs_request_mutex);
                /*
                 * check to see if we were interrupted while waiting for
                 * mutex
                 */
                if (ret < 0) {
                        op->downcall.status = ret;
                        gossip_debug(GOSSIP_WAIT_DEBUG,
                                     "%s: service_operation interrupted.\n",
                                     __func__);
                        return ret;
                }
        }

        /* queue up the operation */
        spin_lock(&orangefs_request_list_lock);
        spin_lock(&op->lock);
        set_op_state_waiting(op);
        gossip_debug(GOSSIP_DEV_DEBUG,
                     "%s: op:%s: op_state:%d: process:%s:\n",
                     __func__,
                     get_opname_string(op),
                     op->op_state,
                     current->comm);
        /* add high priority remount op to the front of the line. */
        if (flags & ORANGEFS_OP_PRIORITY)
                list_add(&op->list, &orangefs_request_list);
        else
                list_add_tail(&op->list, &orangefs_request_list);
        spin_unlock(&op->lock);
        wake_up_interruptible(&orangefs_request_list_waitq);
        if (!__is_daemon_in_service()) {
                gossip_debug(GOSSIP_WAIT_DEBUG,
                             "%s:client core is NOT in service.\n",
                             __func__);
                timeout = op_timeout_secs * HZ;
        }
        spin_unlock(&orangefs_request_list_lock);

        if (!(flags & ORANGEFS_OP_NO_MUTEX))
                mutex_unlock(&orangefs_request_mutex);

        ret = wait_for_matching_downcall(op, timeout,
                                         flags & ORANGEFS_OP_INTERRUPTIBLE);

        gossip_debug(GOSSIP_WAIT_DEBUG,
                     "%s: wait_for_matching_downcall returned %d for %p\n",
                     __func__,
                     ret,
                     op);

        /* got matching downcall; make sure status is in errno format */
        if (!ret) {
                spin_unlock(&op->lock);
                op->downcall.status =
                    orangefs_normalize_to_errno(op->downcall.status);
                ret = op->downcall.status;
                goto out;
        }

        /* failed to get matching downcall */
        if (ret == -ETIMEDOUT) {
                gossip_err("%s: %s -- wait timed out; aborting attempt.\n",
                           __func__,
                           op_name);
        }

        /*
         * remove a waiting op from the request list or
         * remove an in-progress op from the in-progress list.
         */
        orangefs_clean_up_interrupted_operation(op);

        op->downcall.status = ret;
        /* retry if operation has not been serviced and if requested */
        if (ret == -EAGAIN) {
                op->attempts++;
                timeout = op_timeout_secs * HZ;
                gossip_debug(GOSSIP_WAIT_DEBUG,
                             "orangefs: tag %llu (%s)"
                             " -- operation to be retried (%d attempt)\n",
                             llu(op->tag),
                             op_name,
                             op->attempts);

                /*
                 * io ops (ops that use the shared memory buffer) have
                 * to be returned to their caller for a retry. Other ops
                 * can just be recycled here.
                 */
                if (!op->uses_shared_memory)
                        goto retry_servicing;
        }

out:
        gossip_debug(GOSSIP_WAIT_DEBUG,
                     "%s: %s returning: %d for %p.\n",
                     __func__,
                     op_name,
                     ret,
                     op);
        return ret;
}

/* This can get called on an I/O op if it had a bad service_operation. */
bool orangefs_cancel_op_in_progress(struct orangefs_kernel_op_s *op)
{
        u64 tag = op->tag;
        if (!op_state_in_progress(op))
                return false;

        op->slot_to_free = op->upcall.req.io.buf_index;
        memset(&op->upcall, 0, sizeof(op->upcall));
        memset(&op->downcall, 0, sizeof(op->downcall));
        op->upcall.type = ORANGEFS_VFS_OP_CANCEL;
        op->upcall.req.cancel.op_tag = tag;
        op->downcall.type = ORANGEFS_VFS_OP_INVALID;
        op->downcall.status = -1;
        orangefs_new_tag(op);

        spin_lock(&orangefs_request_list_lock);
        /* orangefs_request_list_lock is enough of a barrier here */
        if (!__is_daemon_in_service()) {
                spin_unlock(&orangefs_request_list_lock);
                return false;
        }
        spin_lock(&op->lock);
        set_op_state_waiting(op);
        gossip_debug(GOSSIP_DEV_DEBUG,
                     "%s: op:%s: op_state:%d: process:%s:\n",
                     __func__,
                     get_opname_string(op),
                     op->op_state,
                     current->comm);
        list_add(&op->list, &orangefs_request_list);
        spin_unlock(&op->lock);
        spin_unlock(&orangefs_request_list_lock);

        gossip_debug(GOSSIP_WAIT_DEBUG,
                     "Attempting ORANGEFS operation cancellation of tag %llu\n",
                     llu(tag));
        return true;
}

/*
 * Change an op to the "given up" state and remove it from its list.
 */
static void
        orangefs_clean_up_interrupted_operation(struct orangefs_kernel_op_s *op)
{
        /*
         * handle interrupted cases depending on what state we were in when
         * the interruption is detected.
         *
         * Called with op->lock held.
         */

        /*
         * List manipulation code elsewhere will ignore ops that
         * have been given up upon.
         */
        op->op_state |= OP_VFS_STATE_GIVEN_UP;

        if (list_empty(&op->list)) {
                /* caught copying to/from daemon */
                BUG_ON(op_state_serviced(op));
                spin_unlock(&op->lock);
                wait_for_completion(&op->waitq);
        } else if (op_state_waiting(op)) {
                /*
                 * upcall hasn't been read; remove op from upcall request
                 * list.
                 */
                spin_unlock(&op->lock);
                spin_lock(&orangefs_request_list_lock);
                list_del_init(&op->list);
                spin_unlock(&orangefs_request_list_lock);
                gossip_debug(GOSSIP_WAIT_DEBUG,
                             "Interrupted: Removed op %p from request_list\n",
                             op);
        } else if (op_state_in_progress(op)) {
                /* op must be removed from the in progress htable */
                spin_unlock(&op->lock);
                spin_lock(&orangefs_htable_ops_in_progress_lock);
                list_del_init(&op->list);
                spin_unlock(&orangefs_htable_ops_in_progress_lock);
                gossip_debug(GOSSIP_WAIT_DEBUG,
                             "Interrupted: Removed op %p"
                             " from htable_ops_in_progress\n",
                             op);
        } else {
                spin_unlock(&op->lock);
                gossip_err("interrupted operation is in a weird state 0x%x\n",
                           op->op_state);
        }
        reinit_completion(&op->waitq);
}

/*
 * Sleeps on waitqueue waiting for matching downcall.
 * If client-core finishes servicing, then we are good to go.
 * else if client-core exits, we get woken up here, and retry with a timeout
 *
 * When this call returns to the caller, the specified op will no
 * longer be in either the in_progress hash table or on the request list.
 *
 * Returns 0 on success and -errno on failure
 * Errors are:
 * EAGAIN in case we want the caller to requeue and try again..
 * EINTR/EIO/ETIMEDOUT indicating we are done trying to service this
 * operation since client-core seems to be exiting too often
 * or if we were interrupted.
 *
 * Returns with op->lock taken.
 */
static int wait_for_matching_downcall(struct orangefs_kernel_op_s *op,
                                      long timeout,
                                      bool interruptible)
{
        long n;

        /*
         * There's a "schedule_timeout" inside of these wait
         * primitives, during which the op is out of the hands of the
         * user process that needs something done and is being
         * manipulated by the client-core process.
         */
        if (interruptible)
                n = wait_for_completion_interruptible_timeout(&op->waitq,
                                                              timeout);
        else
                n = wait_for_completion_killable_timeout(&op->waitq, timeout);

        spin_lock(&op->lock);

        if (op_state_serviced(op))
                return 0;

        if (unlikely(n < 0)) {
                gossip_debug(GOSSIP_WAIT_DEBUG,
                             "%s: operation interrupted, tag %llu, %p\n",
                             __func__,
                             llu(op->tag),
                             op);
                return -EINTR;
        }
        if (op_state_purged(op)) {
                gossip_debug(GOSSIP_WAIT_DEBUG,
                             "%s: operation purged, tag %llu, %p, %d\n",
                             __func__,
                             llu(op->tag),
                             op,
                             op->attempts);
                return (op->attempts < ORANGEFS_PURGE_RETRY_COUNT) ?
                         -EAGAIN :
                         -EIO;
        }
        /* must have timed out, then... */
        gossip_debug(GOSSIP_WAIT_DEBUG,
                     "%s: operation timed out, tag %llu, %p, %d)\n",
                     __func__,
                     llu(op->tag),
                     op,
                     op->attempts);
        return -ETIMEDOUT;
}