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Commit 3ac5a675 authored by NeilBrown's avatar NeilBrown Committed by Greg Kroah-Hartman
Browse files

staging: lustre: ldlm: tidy list walking in ldlm_flock() 



Use list_for_each_entry variants to
avoid the explicit list_entry() calls.
This allows us to use list_for_each_entry_safe_from()
instread of adding a local list-walking macro.

Also improve some comments so that it is more obvious
that the locks are sorted per-owner and that we need
to find the insertion point.

Signed-off-by: default avatarNeilBrown <neilb@suse.com>
Reviewed-by: default avatarAndreas Dilger <andreas.dilger@intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 60751d49

drivers/staging/lustre/lustre/ldlm/ldlm_flock.c

+19 −26
Original line number Diff line number Diff line
@@ -59,17 +59,6 @@ 
#include <linux/list.h>

#include "ldlm_internal.h"



/**

 * list_for_remaining_safe - iterate over the remaining entries in a list

 *	      and safeguard against removal of a list entry.

 * \param pos   the &struct list_head to use as a loop counter. pos MUST

 *	      have been initialized prior to using it in this macro.

 * \param n     another &struct list_head to use as temporary storage

 * \param head  the head for your list.

 */

#define list_for_remaining_safe(pos, n, head) \

	for (n = pos->next; pos != (head); pos = n, n = pos->next)



static inline int

ldlm_same_flock_owner(struct ldlm_lock *lock, struct ldlm_lock *new)

{
@@ -125,8 +114,8 @@ static int ldlm_process_flock_lock(struct ldlm_lock *req) 
{

	struct ldlm_resource *res = req->l_resource;

	struct ldlm_namespace *ns = ldlm_res_to_ns(res);

	struct list_head *tmp;

	struct list_head *ownlocks = NULL;

	struct ldlm_lock *tmp;

	struct ldlm_lock *ownlocks = NULL;

	struct ldlm_lock *lock = NULL;

	struct ldlm_lock *new = req;

	struct ldlm_lock *new2 = NULL;
@@ -151,23 +140,23 @@ static int ldlm_process_flock_lock(struct ldlm_lock *req) 
	/* This loop determines where this processes locks start

	 * in the resource lr_granted list.

	 */

	list_for_each(tmp, &res->lr_granted) {

		lock = list_entry(tmp, struct ldlm_lock,

				  l_res_link);

	list_for_each_entry(lock, &res->lr_granted, l_res_link) {

		if (ldlm_same_flock_owner(lock, req)) {

			ownlocks = tmp;

			ownlocks = lock;

			break;

		}

	}



	/* Scan the locks owned by this process that overlap this request.

	/* Scan the locks owned by this process to find the insertion point

	 * (as locks are ordered), and to handle overlaps.

	 * We may have to merge or split existing locks.

	 */

	if (!ownlocks)

		ownlocks = &res->lr_granted;



	list_for_remaining_safe(ownlocks, tmp, &res->lr_granted) {

		lock = list_entry(ownlocks, struct ldlm_lock, l_res_link);

	if (ownlocks)

		lock = ownlocks;

	else

		lock = list_entry(&res->lr_granted,

				  struct ldlm_lock, l_res_link);

	list_for_each_entry_safe_from(lock, tmp, &res->lr_granted, l_res_link) {



		if (!ldlm_same_flock_owner(lock, new))

			break;
@@ -295,7 +284,7 @@ static int ldlm_process_flock_lock(struct ldlm_lock *req) 
						 lock->l_granted_mode);



		/* insert new2 at lock */

		ldlm_resource_add_lock(res, ownlocks, new2);

		ldlm_resource_add_lock(res, &lock->l_res_link, new2);

		LDLM_LOCK_RELEASE(new2);

		break;

	}
@@ -309,8 +298,12 @@ static int ldlm_process_flock_lock(struct ldlm_lock *req) 


	if (!added) {

		list_del_init(&req->l_res_link);

		/* insert new lock before ownlocks in list. */

		ldlm_resource_add_lock(res, ownlocks, req);

		/* insert new lock before "lock", which might be the

		 * next lock for this owner, or might be the first

		 * lock for the next owner, or might not be a lock at

		 * all, but instead points at the head of the list

		 */

		ldlm_resource_add_lock(res, &lock->l_res_link, req);

	}



	/* In case we're reprocessing the requested lock we can't destroy