fs/orangefs/waitqueue.c - kernel/msm-4.19 - Gitiles

 /*
  * (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 "pvfs2-kernel.h"
 #include "pvfs2-bufmap.h"

 /*
  * 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 pvfs2_kernel_op_s *op;

 	spin_lock(&pvfs2_request_list_lock);
 	list_for_each_entry(op, &pvfs2_request_list, list) {
 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			     "pvfs2-client-core: purging op tag %llu %s\n",
 			     llu(op->tag),
 			     get_opname_string(op));
 		spin_lock(&op->lock);
 		set_op_state_purged(op);
 		spin_unlock(&op->lock);
 		wake_up_interruptible(&op->waitq);
 	}
 	spin_unlock(&pvfs2_request_list_lock);
 }

 /*
  * submits a PVFS2 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 pvfs2_kernel_op_s *op,
 		      const char *op_name,
 		      int flags)
 {
 	/* flags to modify behavior */
 	sigset_t orig_sigset;
 	int ret = 0;

 	/* irqflags and wait_entry are only used IF the client-core aborts */
 	unsigned long irqflags;

 	DECLARE_WAITQUEUE(wait_entry, current);

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

 retry_servicing:
 	op->downcall.status = 0;
 	gossip_debug(GOSSIP_WAIT_DEBUG,
 		     "pvfs2: service_operation: %s %p\n",
 		     op_name,
 		     op);
 	gossip_debug(GOSSIP_WAIT_DEBUG,
 		     "pvfs2: operation posted by process: %s, pid: %i\n",
 		     current->comm,
 		     current->pid);

 	/* mask out signals if this operation is not to be interrupted */
 	if (!(flags & PVFS2_OP_INTERRUPTIBLE))
 		mask_blocked_signals(&orig_sigset);

 	if (!(flags & PVFS2_OP_NO_SEMAPHORE)) {
 		ret = mutex_lock_interruptible(&request_mutex);
 		/*
 		 * check to see if we were interrupted while waiting for
 		 * semaphore
 		 */
 		if (ret < 0) {
 			if (!(flags & PVFS2_OP_INTERRUPTIBLE))
 				unmask_blocked_signals(&orig_sigset);
 			op->downcall.status = ret;
 			gossip_debug(GOSSIP_WAIT_DEBUG,
 				     "pvfs2: service_operation interrupted.\n");
 			return ret;
 		}
 	}

 	gossip_debug(GOSSIP_WAIT_DEBUG,
 		     "%s:About to call is_daemon_in_service().\n",
 		     __func__);

 	if (is_daemon_in_service() < 0) {
 		/*
 		 * By incrementing the per-operation attempt counter, we
 		 * directly go into the timeout logic while waiting for
 		 * the matching downcall to be read
 		 */
 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			     "%s:client core is NOT in service(%d).\n",
 			     __func__,
 			     is_daemon_in_service());
 		op->attempts++;
 	}

 	/* queue up the operation */
 	if (flags & PVFS2_OP_PRIORITY) {
 		add_priority_op_to_request_list(op);
 	} else {
 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			     "%s:About to call add_op_to_request_list().\n",
 			     __func__);
 		add_op_to_request_list(op);
 	}

 	if (!(flags & PVFS2_OP_NO_SEMAPHORE))
 		mutex_unlock(&request_mutex);

 	/*
 	 * If we are asked to service an asynchronous operation from
 	 * VFS perspective, we are done.
 	 */
 	if (flags & PVFS2_OP_ASYNC)
 		return 0;

 	if (flags & PVFS2_OP_CANCELLATION) {
 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			     "%s:"
 			     "About to call wait_for_cancellation_downcall.\n",
 			     __func__);
 		ret = wait_for_cancellation_downcall(op);
 	} else {
 		ret = wait_for_matching_downcall(op);
 	}

 	if (ret < 0) {
 		/* failed to get matching downcall */
 		if (ret == -ETIMEDOUT) {
 			gossip_err("pvfs2: %s -- wait timed out; aborting attempt.\n",
 				   op_name);
 		}
 		op->downcall.status = ret;
 	} else {
 		/* got matching downcall; make sure status is in errno format */
 		op->downcall.status =
 		    pvfs2_normalize_to_errno(op->downcall.status);
 		ret = op->downcall.status;
 	}

 	if (!(flags & PVFS2_OP_INTERRUPTIBLE))
 		unmask_blocked_signals(&orig_sigset);

 	BUG_ON(ret != op->downcall.status);
 	/* retry if operation has not been serviced and if requested */
 	if (!op_state_serviced(op) && op->downcall.status == -EAGAIN) {
 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			     "pvfs2: tag %llu (%s)"
 			     " -- operation to be retried (%d attempt)\n",
 			     llu(op->tag),
 			     op_name,
 			     op->attempts + 1);

 		if (!op->uses_shared_memory)
 			/*
 			 * this operation doesn't use the shared memory
 			 * system
 			 */
 			goto retry_servicing;

 		/* op uses shared memory */
 		if (get_bufmap_init() == 0) {
 			/*
 			 * This operation uses the shared memory system AND
 			 * the system is not yet ready. This situation occurs
 			 * when the client-core is restarted AND there were
 			 * operations waiting to be processed or were already
 			 * in process.
 			 */
 			gossip_debug(GOSSIP_WAIT_DEBUG,
 				     "uses_shared_memory is true.\n");
 			gossip_debug(GOSSIP_WAIT_DEBUG,
 				     "Client core in-service status(%d).\n",
 				     is_daemon_in_service());
 			gossip_debug(GOSSIP_WAIT_DEBUG, "bufmap_init:%d.\n",
 				     get_bufmap_init());
 			gossip_debug(GOSSIP_WAIT_DEBUG,
 				     "operation's status is 0x%0x.\n",
 				     op->op_state);

 			/*
 			 * let process sleep for a few seconds so shared
 			 * memory system can be initialized.
 			 */
 			spin_lock_irqsave(&op->lock, irqflags);
 			add_wait_queue(&pvfs2_bufmap_init_waitq, &wait_entry);
 			spin_unlock_irqrestore(&op->lock, irqflags);

 			set_current_state(TASK_INTERRUPTIBLE);

 			/*
 			 * Wait for pvfs_bufmap_initialize() to wake me up
 			 * within the allotted time.
 			 */
 			ret = schedule_timeout(MSECS_TO_JIFFIES
 				(1000 * PVFS2_BUFMAP_WAIT_TIMEOUT_SECS));

 			gossip_debug(GOSSIP_WAIT_DEBUG,
 				     "Value returned from schedule_timeout:"
 				     "%d.\n",
 				     ret);
 			gossip_debug(GOSSIP_WAIT_DEBUG,
 				     "Is shared memory available? (%d).\n",
 				     get_bufmap_init());

 			spin_lock_irqsave(&op->lock, irqflags);
 			remove_wait_queue(&pvfs2_bufmap_init_waitq,
 					  &wait_entry);
 			spin_unlock_irqrestore(&op->lock, irqflags);

 			if (get_bufmap_init() == 0) {
 				gossip_err("%s:The shared memory system has not started in %d seconds after the client core restarted.  Aborting user's request(%s).\n",
 					   __func__,
 					   PVFS2_BUFMAP_WAIT_TIMEOUT_SECS,
 					   get_opname_string(op));
 				return -EIO;
 			}

 			/*
 			 * Return to the calling function and re-populate a
 			 * shared memory buffer.
 			 */
 			return -EAGAIN;
 		}
 	}

 	gossip_debug(GOSSIP_WAIT_DEBUG,
 		     "pvfs2: service_operation %s returning: %d for %p.\n",
 		     op_name,
 		     ret,
 		     op);
 	return ret;
 }

 void pvfs2_clean_up_interrupted_operation(struct pvfs2_kernel_op_s *op)
 {
 	/*
 	 * handle interrupted cases depending on what state we were in when
 	 * the interruption is detected.  there is a coarse grained lock
 	 * across the operation.
 	 *
 	 * NOTE: be sure not to reverse lock ordering by locking an op lock
 	 * while holding the request_list lock.  Here, we first lock the op
 	 * and then lock the appropriate list.
 	 */
 	if (!op) {
 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			    "%s: op is null, ignoring\n",
 			     __func__);
 		return;
 	}

 	/*
 	 * one more sanity check, make sure it's in one of the possible states
 	 * or don't try to cancel it
 	 */
 	if (!(op_state_waiting(op) ||
 	      op_state_in_progress(op) ||
 	      op_state_serviced(op) ||
 	      op_state_purged(op))) {
 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			     "%s: op %p not in a valid state (%0x), "
 			     "ignoring\n",
 			     __func__,
 			     op,
 			     op->op_state);
 		return;
 	}

 	spin_lock(&op->lock);

 	if (op_state_waiting(op)) {
 		/*
 		 * upcall hasn't been read; remove op from upcall request
 		 * list.
 		 */
 		spin_unlock(&op->lock);
 		remove_op_from_request_list(op);
 		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(&htable_ops_in_progress_lock);
 		list_del(&op->list);
 		spin_unlock(&htable_ops_in_progress_lock);
 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			     "Interrupted: Removed op %p"
 			     " from htable_ops_in_progress\n",
 			     op);
 	} else if (!op_state_serviced(op)) {
 		spin_unlock(&op->lock);
 		gossip_err("interrupted operation is in a weird state 0x%x\n",
 			   op->op_state);
 	} else {
 		/*
 		 * It is not intended for execution to flow here,
 		 * but having this unlock here makes sparse happy.
 		 */
 		gossip_err("%s: can't get here.\n", __func__);
 		spin_unlock(&op->lock);
 	}
 }

 /*
  * 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
  *
  * Post when this call returns to the caller, the specified op will no
  * longer be on any list or htable.
  *
  * 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.
  */
 int wait_for_matching_downcall(struct pvfs2_kernel_op_s *op)
 {
 	int ret = -EINVAL;
 	DECLARE_WAITQUEUE(wait_entry, current);

 	spin_lock(&op->lock);
 	add_wait_queue(&op->waitq, &wait_entry);
 	spin_unlock(&op->lock);

 	while (1) {
 		set_current_state(TASK_INTERRUPTIBLE);

 		spin_lock(&op->lock);
 		if (op_state_serviced(op)) {
 			spin_unlock(&op->lock);
 			ret = 0;
 			break;
 		}
 		spin_unlock(&op->lock);

 		if (!signal_pending(current)) {
 			/*
 			 * if this was our first attempt and client-core
 			 * has not purged our operation, we are happy to
 			 * simply wait
 			 */
 			spin_lock(&op->lock);
 			if (op->attempts == 0 && !op_state_purged(op)) {
 				spin_unlock(&op->lock);
 				schedule();
 			} else {
 				spin_unlock(&op->lock);
 				/*
 				 * subsequent attempts, we retry exactly once
 				 * with timeouts
 				 */
 				if (!schedule_timeout(MSECS_TO_JIFFIES
 				      (1000 * op_timeout_secs))) {
 					gossip_debug(GOSSIP_WAIT_DEBUG,
 						     "*** %s:"
 						     " operation timed out (tag"
 						     " %llu, %p, att %d)\n",
 						     __func__,
 						     llu(op->tag),
 						     op,
 						     op->attempts);
 					ret = -ETIMEDOUT;
 					pvfs2_clean_up_interrupted_operation
 					    (op);
 					break;
 				}
 			}
 			spin_lock(&op->lock);
 			op->attempts++;
 			/*
 			 * if the operation was purged in the meantime, it
 			 * is better to requeue it afresh but ensure that
 			 * we have not been purged repeatedly. This could
 			 * happen if client-core crashes when an op
 			 * is being serviced, so we requeue the op, client
 			 * core crashes again so we requeue the op, client
 			 * core starts, and so on...
 			 */
 			if (op_state_purged(op)) {
 				ret = (op->attempts < PVFS2_PURGE_RETRY_COUNT) ?
 					 -EAGAIN :
 					 -EIO;
 				spin_unlock(&op->lock);
 				gossip_debug(GOSSIP_WAIT_DEBUG,
 					     "*** %s:"
 					     " operation purged (tag "
 					     "%llu, %p, att %d)\n",
 					     __func__,
 					     llu(op->tag),
 					     op,
 					     op->attempts);
 				pvfs2_clean_up_interrupted_operation(op);
 				break;
 			}
 			spin_unlock(&op->lock);
 			continue;
 		}

 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			     "*** %s:"
 			     " operation interrupted by a signal (tag "
 			     "%llu, op %p)\n",
 			     __func__,
 			     llu(op->tag),
 			     op);
 		pvfs2_clean_up_interrupted_operation(op);
 		ret = -EINTR;
 		break;
 	}

 	set_current_state(TASK_RUNNING);

 	spin_lock(&op->lock);
 	remove_wait_queue(&op->waitq, &wait_entry);
 	spin_unlock(&op->lock);

 	return ret;
 }

 /*
  * similar to wait_for_matching_downcall(), but used in the special case
  * of I/O cancellations.
  *
  * Note we need a special wait function because if this is called we already
  *      know that a signal is pending in current and need to service the
  *      cancellation upcall anyway.  the only way to exit this is to either
  *      timeout or have the cancellation be serviced properly.
  */
 int wait_for_cancellation_downcall(struct pvfs2_kernel_op_s *op)
 {
 	int ret = -EINVAL;
 	DECLARE_WAITQUEUE(wait_entry, current);

 	spin_lock(&op->lock);
 	add_wait_queue(&op->waitq, &wait_entry);
 	spin_unlock(&op->lock);

 	while (1) {
 		set_current_state(TASK_INTERRUPTIBLE);

 		spin_lock(&op->lock);
 		if (op_state_serviced(op)) {
 			gossip_debug(GOSSIP_WAIT_DEBUG,
 				     "%s:op-state is SERVICED.\n",
 				     __func__);
 			spin_unlock(&op->lock);
 			ret = 0;
 			break;
 		}
 		spin_unlock(&op->lock);

 		if (signal_pending(current)) {
 			gossip_debug(GOSSIP_WAIT_DEBUG,
 				     "%s:operation interrupted by a signal (tag"
 				     " %llu, op %p)\n",
 				     __func__,
 				     llu(op->tag),
 				     op);
 			pvfs2_clean_up_interrupted_operation(op);
 			ret = -EINTR;
 			break;
 		}

 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			     "%s:About to call schedule_timeout.\n",
 			     __func__);
 		ret =
 		    schedule_timeout(MSECS_TO_JIFFIES(1000 * op_timeout_secs));

 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			     "%s:Value returned from schedule_timeout(%d).\n",
 			     __func__,
 			     ret);
 		if (!ret) {
 			gossip_debug(GOSSIP_WAIT_DEBUG,
 				     "%s:*** operation timed out: %p\n",
 				     __func__,
 				     op);
 			pvfs2_clean_up_interrupted_operation(op);
 			ret = -ETIMEDOUT;
 			break;
 		}

 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			     "%s:Breaking out of loop, regardless of value returned by schedule_timeout.\n",
 			     __func__);
 		ret = -ETIMEDOUT;
 		break;
 	}

 	set_current_state(TASK_RUNNING);

 	spin_lock(&op->lock);
 	remove_wait_queue(&op->waitq, &wait_entry);
 	spin_unlock(&op->lock);

 	gossip_debug(GOSSIP_WAIT_DEBUG,
 		     "%s:returning ret(%d)\n",
 		     __func__,
 		     ret);

 	return ret;
 }
	/*
	* (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 "pvfs2-kernel.h"
	#include "pvfs2-bufmap.h"

	/*
	* 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 pvfs2_kernel_op_s *op;

	spin_lock(&pvfs2_request_list_lock);
	list_for_each_entry(op, &pvfs2_request_list, list) {
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"pvfs2-client-core: purging op tag %llu %s\n",
	llu(op->tag),
	get_opname_string(op));
	spin_lock(&op->lock);
	set_op_state_purged(op);
	spin_unlock(&op->lock);
	wake_up_interruptible(&op->waitq);
	}
	spin_unlock(&pvfs2_request_list_lock);
	}

	/*
	* submits a PVFS2 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 pvfs2_kernel_op_s *op,
	const char *op_name,
	int flags)
	{
	/* flags to modify behavior */
	sigset_t orig_sigset;
	int ret = 0;

	/* irqflags and wait_entry are only used IF the client-core aborts */
	unsigned long irqflags;

	DECLARE_WAITQUEUE(wait_entry, current);

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

	retry_servicing:
	op->downcall.status = 0;
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"pvfs2: service_operation: %s %p\n",
	op_name,
	op);
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"pvfs2: operation posted by process: %s, pid: %i\n",
	current->comm,
	current->pid);

	/* mask out signals if this operation is not to be interrupted */
	if (!(flags & PVFS2_OP_INTERRUPTIBLE))
	mask_blocked_signals(&orig_sigset);

	if (!(flags & PVFS2_OP_NO_SEMAPHORE)) {
	ret = mutex_lock_interruptible(&request_mutex);
	/*
	* check to see if we were interrupted while waiting for
	* semaphore
	*/
	if (ret < 0) {
	if (!(flags & PVFS2_OP_INTERRUPTIBLE))
	unmask_blocked_signals(&orig_sigset);
	op->downcall.status = ret;
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"pvfs2: service_operation interrupted.\n");
	return ret;
	}
	}

	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s:About to call is_daemon_in_service().\n",
	__func__);

	if (is_daemon_in_service() < 0) {
	/*
	* By incrementing the per-operation attempt counter, we
	* directly go into the timeout logic while waiting for
	* the matching downcall to be read
	*/
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s:client core is NOT in service(%d).\n",
	__func__,
	is_daemon_in_service());
	op->attempts++;
	}

	/* queue up the operation */
	if (flags & PVFS2_OP_PRIORITY) {
	add_priority_op_to_request_list(op);
	} else {
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s:About to call add_op_to_request_list().\n",
	__func__);
	add_op_to_request_list(op);
	}

	if (!(flags & PVFS2_OP_NO_SEMAPHORE))
	mutex_unlock(&request_mutex);

	/*
	* If we are asked to service an asynchronous operation from
	* VFS perspective, we are done.
	*/
	if (flags & PVFS2_OP_ASYNC)
	return 0;

	if (flags & PVFS2_OP_CANCELLATION) {
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s:"
	"About to call wait_for_cancellation_downcall.\n",
	__func__);
	ret = wait_for_cancellation_downcall(op);
	} else {
	ret = wait_for_matching_downcall(op);
	}

	if (ret < 0) {
	/* failed to get matching downcall */
	if (ret == -ETIMEDOUT) {
	gossip_err("pvfs2: %s -- wait timed out; aborting attempt.\n",
	op_name);
	}
	op->downcall.status = ret;
	} else {
	/* got matching downcall; make sure status is in errno format */
	op->downcall.status =
	pvfs2_normalize_to_errno(op->downcall.status);
	ret = op->downcall.status;
	}

	if (!(flags & PVFS2_OP_INTERRUPTIBLE))
	unmask_blocked_signals(&orig_sigset);

	BUG_ON(ret != op->downcall.status);
	/* retry if operation has not been serviced and if requested */
	if (!op_state_serviced(op) && op->downcall.status == -EAGAIN) {
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"pvfs2: tag %llu (%s)"
	" -- operation to be retried (%d attempt)\n",
	llu(op->tag),
	op_name,
	op->attempts + 1);

	if (!op->uses_shared_memory)
	/*
	* this operation doesn't use the shared memory
	* system
	*/
	goto retry_servicing;

	/* op uses shared memory */
	if (get_bufmap_init() == 0) {
	/*
	* This operation uses the shared memory system AND
	* the system is not yet ready. This situation occurs
	* when the client-core is restarted AND there were
	* operations waiting to be processed or were already
	* in process.
	*/
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"uses_shared_memory is true.\n");
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"Client core in-service status(%d).\n",
	is_daemon_in_service());
	gossip_debug(GOSSIP_WAIT_DEBUG, "bufmap_init:%d.\n",
	get_bufmap_init());
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"operation's status is 0x%0x.\n",
	op->op_state);

	/*
	* let process sleep for a few seconds so shared
	* memory system can be initialized.
	*/
	spin_lock_irqsave(&op->lock, irqflags);
	add_wait_queue(&pvfs2_bufmap_init_waitq, &wait_entry);
	spin_unlock_irqrestore(&op->lock, irqflags);

	set_current_state(TASK_INTERRUPTIBLE);

	/*
	* Wait for pvfs_bufmap_initialize() to wake me up
	* within the allotted time.
	*/
	ret = schedule_timeout(MSECS_TO_JIFFIES
	(1000 * PVFS2_BUFMAP_WAIT_TIMEOUT_SECS));

	gossip_debug(GOSSIP_WAIT_DEBUG,
	"Value returned from schedule_timeout:"
	"%d.\n",
	ret);
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"Is shared memory available? (%d).\n",
	get_bufmap_init());

	spin_lock_irqsave(&op->lock, irqflags);
	remove_wait_queue(&pvfs2_bufmap_init_waitq,
	&wait_entry);
	spin_unlock_irqrestore(&op->lock, irqflags);

	if (get_bufmap_init() == 0) {
	gossip_err("%s:The shared memory system has not started in %d seconds after the client core restarted. Aborting user's request(%s).\n",
	__func__,
	PVFS2_BUFMAP_WAIT_TIMEOUT_SECS,
	get_opname_string(op));
	return -EIO;
	}

	/*
	* Return to the calling function and re-populate a
	* shared memory buffer.
	*/
	return -EAGAIN;
	}
	}

	gossip_debug(GOSSIP_WAIT_DEBUG,
	"pvfs2: service_operation %s returning: %d for %p.\n",
	op_name,
	ret,
	op);
	return ret;
	}

	void pvfs2_clean_up_interrupted_operation(struct pvfs2_kernel_op_s *op)
	{
	/*
	* handle interrupted cases depending on what state we were in when
	* the interruption is detected. there is a coarse grained lock
	* across the operation.
	*
	* NOTE: be sure not to reverse lock ordering by locking an op lock
	* while holding the request_list lock. Here, we first lock the op
	* and then lock the appropriate list.
	*/
	if (!op) {
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s: op is null, ignoring\n",
	__func__);
	return;
	}

	/*
	* one more sanity check, make sure it's in one of the possible states
	* or don't try to cancel it
	*/
	if (!(op_state_waiting(op) \|\|
	op_state_in_progress(op) \|\|
	op_state_serviced(op) \|\|
	op_state_purged(op))) {
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s: op %p not in a valid state (%0x), "
	"ignoring\n",
	__func__,
	op,
	op->op_state);
	return;
	}

	spin_lock(&op->lock);

	if (op_state_waiting(op)) {
	/*
	* upcall hasn't been read; remove op from upcall request
	* list.
	*/
	spin_unlock(&op->lock);
	remove_op_from_request_list(op);
	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(&htable_ops_in_progress_lock);
	list_del(&op->list);
	spin_unlock(&htable_ops_in_progress_lock);
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"Interrupted: Removed op %p"
	" from htable_ops_in_progress\n",
	op);
	} else if (!op_state_serviced(op)) {
	spin_unlock(&op->lock);
	gossip_err("interrupted operation is in a weird state 0x%x\n",
	op->op_state);
	} else {
	/*
	* It is not intended for execution to flow here,
	* but having this unlock here makes sparse happy.
	*/
	gossip_err("%s: can't get here.\n", __func__);
	spin_unlock(&op->lock);
	}
	}

	/*
	* 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
	*
	* Post when this call returns to the caller, the specified op will no
	* longer be on any list or htable.
	*
	* 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.
	*/
	int wait_for_matching_downcall(struct pvfs2_kernel_op_s *op)
	{
	int ret = -EINVAL;
	DECLARE_WAITQUEUE(wait_entry, current);

	spin_lock(&op->lock);
	add_wait_queue(&op->waitq, &wait_entry);
	spin_unlock(&op->lock);

	while (1) {
	set_current_state(TASK_INTERRUPTIBLE);

	spin_lock(&op->lock);
	if (op_state_serviced(op)) {
	spin_unlock(&op->lock);
	ret = 0;
	break;
	}
	spin_unlock(&op->lock);

	if (!signal_pending(current)) {
	/*
	* if this was our first attempt and client-core
	* has not purged our operation, we are happy to
	* simply wait
	*/
	spin_lock(&op->lock);
	if (op->attempts == 0 && !op_state_purged(op)) {
	spin_unlock(&op->lock);
	schedule();
	} else {
	spin_unlock(&op->lock);
	/*
	* subsequent attempts, we retry exactly once
	* with timeouts
	*/
	if (!schedule_timeout(MSECS_TO_JIFFIES
	(1000 * op_timeout_secs))) {
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"*** %s:"
	" operation timed out (tag"
	" %llu, %p, att %d)\n",
	__func__,
	llu(op->tag),
	op,
	op->attempts);
	ret = -ETIMEDOUT;
	pvfs2_clean_up_interrupted_operation
	(op);
	break;
	}
	}
	spin_lock(&op->lock);
	op->attempts++;
	/*
	* if the operation was purged in the meantime, it
	* is better to requeue it afresh but ensure that
	* we have not been purged repeatedly. This could
	* happen if client-core crashes when an op
	* is being serviced, so we requeue the op, client
	* core crashes again so we requeue the op, client
	* core starts, and so on...
	*/
	if (op_state_purged(op)) {
	ret = (op->attempts < PVFS2_PURGE_RETRY_COUNT) ?
	-EAGAIN :
	-EIO;
	spin_unlock(&op->lock);
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"*** %s:"
	" operation purged (tag "
	"%llu, %p, att %d)\n",
	__func__,
	llu(op->tag),
	op,
	op->attempts);
	pvfs2_clean_up_interrupted_operation(op);
	break;
	}
	spin_unlock(&op->lock);
	continue;
	}

	gossip_debug(GOSSIP_WAIT_DEBUG,
	"*** %s:"
	" operation interrupted by a signal (tag "
	"%llu, op %p)\n",
	__func__,
	llu(op->tag),
	op);
	pvfs2_clean_up_interrupted_operation(op);
	ret = -EINTR;
	break;
	}

	set_current_state(TASK_RUNNING);

	spin_lock(&op->lock);
	remove_wait_queue(&op->waitq, &wait_entry);
	spin_unlock(&op->lock);

	return ret;
	}

	/*
	* similar to wait_for_matching_downcall(), but used in the special case
	* of I/O cancellations.
	*
	* Note we need a special wait function because if this is called we already
	* know that a signal is pending in current and need to service the
	* cancellation upcall anyway. the only way to exit this is to either
	* timeout or have the cancellation be serviced properly.
	*/
	int wait_for_cancellation_downcall(struct pvfs2_kernel_op_s *op)
	{
	int ret = -EINVAL;
	DECLARE_WAITQUEUE(wait_entry, current);

	spin_lock(&op->lock);
	add_wait_queue(&op->waitq, &wait_entry);
	spin_unlock(&op->lock);

	while (1) {
	set_current_state(TASK_INTERRUPTIBLE);

	spin_lock(&op->lock);
	if (op_state_serviced(op)) {
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s:op-state is SERVICED.\n",
	__func__);
	spin_unlock(&op->lock);
	ret = 0;
	break;
	}
	spin_unlock(&op->lock);

	if (signal_pending(current)) {
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s:operation interrupted by a signal (tag"
	" %llu, op %p)\n",
	__func__,
	llu(op->tag),
	op);
	pvfs2_clean_up_interrupted_operation(op);
	ret = -EINTR;
	break;
	}

	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s:About to call schedule_timeout.\n",
	__func__);
	ret =
	schedule_timeout(MSECS_TO_JIFFIES(1000 * op_timeout_secs));

	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s:Value returned from schedule_timeout(%d).\n",
	__func__,
	ret);
	if (!ret) {
	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s:*** operation timed out: %p\n",
	__func__,
	op);
	pvfs2_clean_up_interrupted_operation(op);
	ret = -ETIMEDOUT;
	break;
	}

	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s:Breaking out of loop, regardless of value returned by schedule_timeout.\n",
	__func__);
	ret = -ETIMEDOUT;
	break;
	}

	set_current_state(TASK_RUNNING);

	spin_lock(&op->lock);
	remove_wait_queue(&op->waitq, &wait_entry);
	spin_unlock(&op->lock);

	gossip_debug(GOSSIP_WAIT_DEBUG,
	"%s:returning ret(%d)\n",
	__func__,
	ret);

	return ret;
	}