[lustre-devel] [PATCH 04/21] lustre: use list*entry macros in place of container_of()

[NeilBrown]

There are a number of places that use container_of() but where
list_first_entry(), or list_last_entry() make the meaning more clear.
So change them over.

Signed-off-by: NeilBrown <neilb at suse.com>
---
 drivers/staging/lustre/lustre/ldlm/ldlm_resource.c |    4 ++--
 drivers/staging/lustre/lustre/obdclass/cl_io.c     |    4 ++--
 drivers/staging/lustre/lustre/obdclass/cl_object.c |   13 ++++++++-----
 drivers/staging/lustre/lustre/obdclass/cl_page.c   |    4 ++--
 drivers/staging/lustre/lustre/obdclass/lu_object.c |    7 +++----
 5 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c b/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c
index 85c5047f4ba2..74c7644d6ef8 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c
@@ -987,8 +987,8 @@ struct ldlm_namespace *ldlm_namespace_first_locked(enum ldlm_side client)
 {
 	LASSERT(mutex_is_locked(ldlm_namespace_lock(client)));
 	LASSERT(!list_empty(ldlm_namespace_list(client)));
-	return container_of(ldlm_namespace_list(client)->next,
-		struct ldlm_namespace, ns_list_chain);
+	return list_first_entry(ldlm_namespace_list(client),
+				struct ldlm_namespace, ns_list_chain);
 }
 
 /** Create and initialize new resource. */
diff --git a/drivers/staging/lustre/lustre/obdclass/cl_io.c b/drivers/staging/lustre/lustre/obdclass/cl_io.c
index 7bf02350f19d..34b4e63e7d1a 100644
--- a/drivers/staging/lustre/lustre/obdclass/cl_io.c
+++ b/drivers/staging/lustre/lustre/obdclass/cl_io.c
@@ -93,8 +93,8 @@ void cl_io_fini(const struct lu_env *env, struct cl_io *io)
 	LINVRNT(cl_io_invariant(io));
 
 	while (!list_empty(&io->ci_layers)) {
-		slice = container_of(io->ci_layers.prev, struct cl_io_slice,
-				     cis_linkage);
+		slice = list_last_entry(&io->ci_layers, struct cl_io_slice,
+					cis_linkage);
 		list_del_init(&slice->cis_linkage);
 		if (slice->cis_iop->op[io->ci_type].cio_fini)
 			slice->cis_iop->op[io->ci_type].cio_fini(env, slice);
diff --git a/drivers/staging/lustre/lustre/obdclass/cl_object.c b/drivers/staging/lustre/lustre/obdclass/cl_object.c
index 05d784ae7a6c..f724b2d62df1 100644
--- a/drivers/staging/lustre/lustre/obdclass/cl_object.c
+++ b/drivers/staging/lustre/lustre/obdclass/cl_object.c
@@ -649,8 +649,8 @@ static struct lu_env *cl_env_obtain(void *debug)
 	if (cl_envs[cpu].cec_count > 0) {
 		int rc;
 
-		cle = container_of(cl_envs[cpu].cec_envs.next, struct cl_env,
-				   ce_linkage);
+		cle = list_first_entry(&cl_envs[cpu].cec_envs, struct cl_env,
+				       ce_linkage);
 		list_del_init(&cle->ce_linkage);
 		cl_envs[cpu].cec_count--;
 		read_unlock(&cl_envs[cpu].cec_guard);
@@ -748,9 +748,12 @@ unsigned int cl_env_cache_purge(unsigned int nr)
 
 	for_each_possible_cpu(i) {
 		write_lock(&cl_envs[i].cec_guard);
-		for (; !list_empty(&cl_envs[i].cec_envs) && nr > 0; --nr) {
-			cle = container_of(cl_envs[i].cec_envs.next,
-					   struct cl_env, ce_linkage);
+		for (; nr >0 &&
+			     (cle = list_first_entry_or_null(
+				     &cl_envs[i].cec_envs,
+				     struct cl_env,
+				     ce_linkage)) != NULL;
+		     --nr) {
 			list_del_init(&cle->ce_linkage);
 			LASSERT(cl_envs[i].cec_count > 0);
 			cl_envs[i].cec_count--;
diff --git a/drivers/staging/lustre/lustre/obdclass/cl_page.c b/drivers/staging/lustre/lustre/obdclass/cl_page.c
index b1b4dc7ea22f..d025ea55818f 100644
--- a/drivers/staging/lustre/lustre/obdclass/cl_page.c
+++ b/drivers/staging/lustre/lustre/obdclass/cl_page.c
@@ -690,8 +690,8 @@ int cl_page_is_vmlocked(const struct lu_env *env, const struct cl_page *pg)
 	const struct cl_page_slice *slice;
 	int result;
 
-	slice = container_of(pg->cp_layers.next,
-			     const struct cl_page_slice, cpl_linkage);
+	slice = list_first_entry(&pg->cp_layers,
+				 const struct cl_page_slice, cpl_linkage);
 	PASSERT(env, pg, slice->cpl_ops->cpo_is_vmlocked);
 	/*
 	 * Call ->cpo_is_vmlocked() directly instead of going through
diff --git a/drivers/staging/lustre/lustre/obdclass/lu_object.c b/drivers/staging/lustre/lustre/obdclass/lu_object.c
index 3bd48748f46c..639c298b6a90 100644
--- a/drivers/staging/lustre/lustre/obdclass/lu_object.c
+++ b/drivers/staging/lustre/lustre/obdclass/lu_object.c
@@ -349,7 +349,7 @@ static void lu_object_free(const struct lu_env *env, struct lu_object *o)
 		 * lives as long as possible and ->loo_object_free() methods
 		 * can look at its contents.
 		 */
-		o = container_of(splice.prev, struct lu_object, lo_linkage);
+		o = list_last_entry(&splice, struct lu_object, lo_linkage);
 		list_del_init(&o->lo_linkage);
 		o->lo_ops->loo_object_free(env, o);
 	}
@@ -432,9 +432,8 @@ int lu_site_purge_objects(const struct lu_env *env, struct lu_site *s,
 		 * Free everything on the dispose list. This is safe against
 		 * races due to the reasons described in lu_object_put().
 		 */
-		while (!list_empty(&dispose)) {
-			h = container_of(dispose.next,
-					 struct lu_object_header, loh_lru);
+		while ((h = list_first_entry_or_null(
+				&dispose, struct lu_object_header, loh_lru)) != NULL) {
 			list_del_init(&h->loh_lru);
 			lu_object_free(env, lu_object_top(h));
 			lprocfs_counter_incr(s->ls_stats, LU_SS_LRU_PURGED);