staging: lustre: add container_of_safe()

Luster has a container_of0() function which is similar to
container_of() but passes an IS_ERR_OR_NULL() pointer through
unchanged.
This could be generally useful: bcache at last has a similar function.

Naming is hard, but the precedent set by hlist_entry_safe() suggests
a _safe suffix might be most consistent.

So add container_of_safe() to kernel.h, and replace all occurrences of
container_of0() with one of
  - list_first_entry, list_next_entry, when that is a better fit,
  - container_of(), when the pointer is used as a validpointer in
    surrounding code,
  - container_of_safe() when there is no obviously better alternative.

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 8 insertions, 8 deletions

diff --git a/drivers/staging/lustre/lustre/osc/osc_cl_internal.h b/drivers/staging/lustre/lustre/osc/osc_cl_internal.h
index 1449013722f6..dc25dd12d7d5 100644
--- a/drivers/staging/lustre/lustre/osc/osc_cl_internal.h
+++ b/drivers/staging/lustre/lustre/osc/osc_cl_internal.h
@@ -460,7 +460,7 @@ static inline int osc_is_object(const struct lu_object *obj)
 static inline struct osc_device *lu2osc_dev(const struct lu_device *d)
 {
 	LINVRNT(d->ld_type == &osc_device_type);
-	return container_of0(d, struct osc_device, od_cl.cd_lu_dev);
+	return container_of(d, struct osc_device, od_cl.cd_lu_dev);
 }
 
 static inline struct obd_export *osc_export(const struct osc_object *obj)
@@ -476,7 +476,7 @@ static inline struct client_obd *osc_cli(const struct osc_object *obj)
 static inline struct osc_object *cl2osc(const struct cl_object *obj)
 {
 	LINVRNT(osc_is_object(&obj->co_lu));
-	return container_of0(obj, struct osc_object, oo_cl);
+	return container_of(obj, struct osc_object, oo_cl);
 }
 
 static inline struct cl_object *osc2cl(const struct osc_object *obj)
@@ -509,12 +509,12 @@ static inline enum cl_lock_mode osc_ldlm2cl_lock(enum ldlm_mode mode)
 static inline struct osc_page *cl2osc_page(const struct cl_page_slice *slice)
 {
 	LINVRNT(osc_is_object(&slice->cpl_obj->co_lu));
-	return container_of0(slice, struct osc_page, ops_cl);
+	return container_of(slice, struct osc_page, ops_cl);
 }
 
 static inline struct osc_page *oap2osc(struct osc_async_page *oap)
 {
-	return container_of0(oap, struct osc_page, ops_oap);
+	return container_of_safe(oap, struct osc_page, ops_oap);
 }
 
 static inline pgoff_t osc_index(struct osc_page *opg)
@@ -545,7 +545,7 @@ osc_cl_page_osc(struct cl_page *page, struct osc_object *osc)
 static inline struct osc_lock *cl2osc_lock(const struct cl_lock_slice *slice)
 {
 	LINVRNT(osc_is_object(&slice->cls_obj->co_lu));
-	return container_of0(slice, struct osc_lock, ols_cl);
+	return container_of(slice, struct osc_lock, ols_cl);
 }
 
 static inline struct osc_lock *osc_lock_at(const struct cl_lock *lock)
diff --git a/drivers/staging/lustre/lustre/osc/osc_internal.h b/drivers/staging/lustre/lustre/osc/osc_internal.h
index 1c8ba4ad6e7f..fca020568c19 100644
--- a/drivers/staging/lustre/lustre/osc/osc_internal.h
+++ b/drivers/staging/lustre/lustre/osc/osc_internal.h
@@ -180,7 +180,7 @@ struct osc_device {
 
 static inline struct osc_device *obd2osc_dev(const struct obd_device *d)
 {
-	return container_of0(d->obd_lu_dev, struct osc_device, od_cl.cd_lu_dev);
+	return container_of_safe(d->obd_lu_dev, struct osc_device, od_cl.cd_lu_dev);
 }
 
 extern struct lu_kmem_descr osc_caches[];
diff --git a/drivers/staging/lustre/lustre/osc/osc_io.c b/drivers/staging/lustre/lustre/osc/osc_io.c
index 76743faf3e6d..67734a8ed331 100644
--- a/drivers/staging/lustre/lustre/osc/osc_io.c
+++ b/drivers/staging/lustre/lustre/osc/osc_io.c
@@ -55,7 +55,7 @@
 static struct osc_io *cl2osc_io(const struct lu_env *env,
 				const struct cl_io_slice *slice)
 {
-	struct osc_io *oio = container_of0(slice, struct osc_io, oi_cl);
+	struct osc_io *oio = container_of_safe(slice, struct osc_io, oi_cl);
 
 	LINVRNT(oio == osc_env_io(env));
 	return oio;
diff --git a/drivers/staging/lustre/lustre/osc/osc_object.c b/drivers/staging/lustre/lustre/osc/osc_object.c
index 4f81dd16f4f5..84240181c7ea 100644
--- a/drivers/staging/lustre/lustre/osc/osc_object.c
+++ b/drivers/staging/lustre/lustre/osc/osc_object.c
@@ -58,7 +58,7 @@ static struct lu_object *osc2lu(struct osc_object *osc)
 static struct osc_object *lu2osc(const struct lu_object *obj)
 {
 	LINVRNT(osc_is_object(obj));
-	return container_of0(obj, struct osc_object, oo_cl.co_lu);
+	return container_of(obj, struct osc_object, oo_cl.co_lu);
 }
 
 /*****************************************************************************