X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=blobdiff_plain;f=lustre%2Fobdclass%2Flocal_storage.c;h=2cc4afe02c8023c5fe1bf1018b608fa0262f6eab;hp=179c32357954ec9c53f3ca226705c48bd1f525b6;hb=907a321c9b9e2cd5f5ccf488cc516ba05dee0ad8;hpb=98060d83459ba10409f295898f0ec917f938b4d3

diff --git a/lustre/obdclass/local_storage.c b/lustre/obdclass/local_storage.c
index 179c323..2cc4afe 100644
--- a/lustre/obdclass/local_storage.c
+++ b/lustre/obdclass/local_storage.c
@@ -20,7 +20,7 @@
  * GPL HEADER END
  */
 /*
- * Copyright (c) 2012, 2013, Intel Corporation.
+ * Copyright (c) 2012, 2014, Intel Corporation.
  */
 /*
  * lustre/obdclass/local_storage.c
@@ -35,7 +35,7 @@
 #include "local_storage.h"
 
 /* all initialized local storages on this node are linked on this */
-static CFS_LIST_HEAD(ls_list_head);
+static struct list_head ls_list_head = LIST_HEAD_INIT(ls_list_head);
 static DEFINE_MUTEX(ls_list_mutex);
 
 static int ls_object_init(const struct lu_env *env, struct lu_object *o,
@@ -68,14 +68,14 @@ static void ls_object_free(const struct lu_env *env, struct lu_object *o)
 	OBD_FREE_PTR(obj);
 }
 
-struct lu_object_operations ls_lu_obj_ops = {
+static struct lu_object_operations ls_lu_obj_ops = {
 	.loo_object_init  = ls_object_init,
 	.loo_object_free  = ls_object_free,
 };
 
-struct lu_object *ls_object_alloc(const struct lu_env *env,
-				  const struct lu_object_header *_h,
-				  struct lu_device *d)
+static struct lu_object *ls_object_alloc(const struct lu_env *env,
+					 const struct lu_object_header *_h,
+					 struct lu_device *d)
 {
 	struct lu_object_header	*h;
 	struct ls_object	*o;
@@ -108,9 +108,9 @@ static struct ls_device *__ls_find_dev(struct dt_device *dev)
 {
 	struct ls_device *ls, *ret = NULL;
 
-	cfs_list_for_each_entry(ls, &ls_list_head, ls_linkage) {
+	list_for_each_entry(ls, &ls_list_head, ls_linkage) {
 		if (ls->ls_osd == dev) {
-			cfs_atomic_inc(&ls->ls_refcount);
+			atomic_inc(&ls->ls_refcount);
 			ret = ls;
 			break;
 		}
@@ -155,8 +155,8 @@ struct ls_device *ls_device_get(struct dt_device *dev)
 	if (ls == NULL)
 		GOTO(out_ls, ls = ERR_PTR(-ENOMEM));
 
-	cfs_atomic_set(&ls->ls_refcount, 1);
-	CFS_INIT_LIST_HEAD(&ls->ls_los_list);
+	atomic_set(&ls->ls_refcount, 1);
+	INIT_LIST_HEAD(&ls->ls_los_list);
 	mutex_init(&ls->ls_los_mutex);
 
 	ls->ls_osd = dev;
@@ -167,7 +167,7 @@ struct ls_device *ls_device_get(struct dt_device *dev)
 	ls->ls_top_dev.dd_lu_dev.ld_site = dev->dd_lu_dev.ld_site;
 
 	/* finally add ls to the list */
-	cfs_list_add(&ls->ls_linkage, &ls_list_head);
+	list_add(&ls->ls_linkage, &ls_list_head);
 out_ls:
 	mutex_unlock(&ls_list_mutex);
 	RETURN(ls);
@@ -176,13 +176,13 @@ out_ls:
 void ls_device_put(const struct lu_env *env, struct ls_device *ls)
 {
 	LASSERT(env);
-	if (!cfs_atomic_dec_and_test(&ls->ls_refcount))
+	if (!atomic_dec_and_test(&ls->ls_refcount))
 		return;
 
 	mutex_lock(&ls_list_mutex);
-	if (cfs_atomic_read(&ls->ls_refcount) == 0) {
-		LASSERT(cfs_list_empty(&ls->ls_los_list));
-		cfs_list_del(&ls->ls_linkage);
+	if (atomic_read(&ls->ls_refcount) == 0) {
+		LASSERT(list_empty(&ls->ls_los_list));
+		list_del(&ls->ls_linkage);
 		lu_site_purge(env, ls->ls_top_dev.dd_lu_dev.ld_site, ~0);
 		lu_device_fini(&ls->ls_top_dev.dd_lu_dev);
 		OBD_FREE_PTR(ls);
@@ -208,7 +208,7 @@ int local_object_fid_generate(const struct lu_env *env,
 
 	mutex_lock(&los->los_id_lock);
 	fid->f_seq = los->los_seq;
-	fid->f_oid = los->los_last_oid++;
+	fid->f_oid = ++los->los_last_oid;
 	fid->f_ver = 0;
 	mutex_unlock(&los->los_id_lock);
 
@@ -229,8 +229,10 @@ int local_object_declare_create(const struct lu_env *env,
 	/* update fid generation file */
 	if (los != NULL) {
 		LASSERT(dt_object_exists(los->los_obj));
+		dti->dti_lb.lb_buf = NULL;
+		dti->dti_lb.lb_len = sizeof(struct los_ondisk);
 		rc = dt_declare_record_write(env, los->los_obj,
-					     sizeof(struct los_ondisk), 0, th);
+					     &dti->dti_lb, 0, th);
 		if (rc)
 			RETURN(rc);
 	}
@@ -252,7 +254,7 @@ int local_object_create(const struct lu_env *env,
 			struct dt_object_format *dof, struct thandle *th)
 {
 	struct dt_thread_info	*dti = dt_info(env);
-	struct los_ondisk	 losd;
+	u64			 lastid;
 	int			 rc;
 
 	ENTRY;
@@ -274,12 +276,11 @@ int local_object_create(const struct lu_env *env,
 
 	/* update local oid number on disk so that
 	 * we know the last one used after reboot */
-	losd.lso_magic = cpu_to_le32(LOS_MAGIC);
-	losd.lso_next_oid = cpu_to_le32(los->los_last_oid);
+	lastid = cpu_to_le64(los->los_last_oid);
 
 	dti->dti_off = 0;
-	dti->dti_lb.lb_buf = &losd;
-	dti->dti_lb.lb_len = sizeof(losd);
+	dti->dti_lb.lb_buf = &lastid;
+	dti->dti_lb.lb_len = sizeof(lastid);
 	rc = dt_record_write(env, los->los_obj, &dti->dti_lb, &dti->dti_off,
 			     th);
 	mutex_unlock(&los->los_id_lock);
@@ -290,20 +291,28 @@ int local_object_create(const struct lu_env *env,
 /*
  * Create local named object (file, directory or index) in parent directory.
  */
-struct dt_object *__local_file_create(const struct lu_env *env,
-				      const struct lu_fid *fid,
-				      struct local_oid_storage *los,
-				      struct ls_device *ls,
-				      struct dt_object *parent,
-				      const char *name, struct lu_attr *attr,
-				      struct dt_object_format *dof)
+static struct dt_object *__local_file_create(const struct lu_env *env,
+					     const struct lu_fid *fid,
+					     struct local_oid_storage *los,
+					     struct ls_device *ls,
+					     struct dt_object *parent,
+					     const char *name,
+					     struct lu_attr *attr,
+					     struct dt_object_format *dof)
 {
-	struct dt_thread_info	*dti = dt_info(env);
+	struct dt_thread_info	*dti	= dt_info(env);
+	struct lu_object_conf	*conf	= &dti->dti_conf;
+	struct dt_insert_rec	*rec	= &dti->dti_dt_rec;
 	struct dt_object	*dto;
 	struct thandle		*th;
 	int			 rc;
 
-	dto = ls_locate(env, ls, fid);
+	/* We know that the target object does not exist, to be created,
+	 * then give some hints - LOC_F_NEW to help low layer to handle
+	 * that efficiently and properly. */
+	memset(conf, 0, sizeof(*conf));
+	conf->loc_flags = LOC_F_NEW;
+	dto = ls_locate(env, ls, fid, conf);
 	if (unlikely(IS_ERR(dto)))
 		RETURN(dto);
 
@@ -320,11 +329,19 @@ struct dt_object *__local_file_create(const struct lu_env *env,
 		GOTO(trans_stop, rc);
 
 	if (dti->dti_dof.dof_type == DFT_DIR) {
-		dt_declare_ref_add(env, dto, th);
-		dt_declare_ref_add(env, parent, th);
+		rc = dt_declare_ref_add(env, dto, th);
+		if (rc < 0)
+			GOTO(trans_stop, rc);
+
+		rc = dt_declare_ref_add(env, parent, th);
+		if (rc < 0)
+			GOTO(trans_stop, rc);
 	}
 
-	rc = dt_declare_insert(env, parent, (void *)fid, (void *)name, th);
+	rec->rec_fid = fid;
+	rec->rec_type = dto->do_lu.lo_header->loh_attr;
+	rc = dt_declare_insert(env, parent, (const struct dt_rec *)rec,
+			       (const struct dt_key *)name, th);
 	if (rc)
 		GOTO(trans_stop, rc);
 
@@ -346,20 +363,27 @@ struct dt_object *__local_file_create(const struct lu_env *env,
 	if (dti->dti_dof.dof_type == DFT_DIR) {
 		if (!dt_try_as_dir(env, dto))
 			GOTO(destroy, rc = -ENOTDIR);
+
+		rec->rec_type = S_IFDIR;
+		rec->rec_fid = fid;
 		/* Add "." and ".." for newly created dir */
-		rc = dt_insert(env, dto, (void *)fid, (void *)".", th,
-			       BYPASS_CAPA, 1);
-		if (rc)
+		rc = dt_insert(env, dto, (const struct dt_rec *)rec,
+			       (const struct dt_key *)".", th, BYPASS_CAPA, 1);
+		if (rc != 0)
 			GOTO(destroy, rc);
+
 		dt_ref_add(env, dto, th);
-		rc = dt_insert(env, dto, (void *)lu_object_fid(&parent->do_lu),
-			       (void *)"..", th, BYPASS_CAPA, 1);
-		if (rc)
+		rec->rec_fid = lu_object_fid(&parent->do_lu);
+		rc = dt_insert(env, dto, (const struct dt_rec *)rec,
+			       (const struct dt_key *)"..", th, BYPASS_CAPA, 1);
+		if (rc != 0)
 			GOTO(destroy, rc);
 	}
 
+	rec->rec_fid = fid;
+	rec->rec_type = dto->do_lu.lo_header->loh_attr;
 	dt_write_lock(env, parent, 0);
-	rc = dt_insert(env, parent, (const struct dt_rec *)fid,
+	rc = dt_insert(env, parent, (const struct dt_rec *)rec,
 		       (const struct dt_key *)name, th, BYPASS_CAPA, 1);
 	if (dti->dti_dof.dof_type == DFT_DIR)
 		dt_ref_add(env, parent, th);
@@ -399,7 +423,8 @@ struct dt_object *local_file_find_or_create(const struct lu_env *env,
 	rc = dt_lookup_dir(env, parent, name, &dti->dti_fid);
 	if (rc == 0)
 		/* name is found, get the object */
-		dto = ls_locate(env, dt2ls_dev(los->los_dev), &dti->dti_fid);
+		dto = ls_locate(env, dt2ls_dev(los->los_dev),
+				&dti->dti_fid, NULL);
 	else if (rc != -ENOENT)
 		dto = ERR_PTR(rc);
 	else {
@@ -486,7 +511,8 @@ struct dt_object *local_index_find_or_create(const struct lu_env *env,
 	rc = dt_lookup_dir(env, parent, name, &dti->dti_fid);
 	if (rc == 0) {
 		/* name is found, get the object */
-		dto = ls_locate(env, dt2ls_dev(los->los_dev), &dti->dti_fid);
+		dto = ls_locate(env, dt2ls_dev(los->los_dev),
+				&dti->dti_fid, NULL);
 	} else if (rc != -ENOENT) {
 		dto = ERR_PTR(rc);
 	} else {
@@ -620,8 +646,11 @@ int local_object_unlink(const struct lu_env *env, struct dt_device *dt,
 
 	rc = dt_ref_del(env, dto, th);
 	if (rc < 0) {
-		rc = dt_insert(env, parent,
-			       (const struct dt_rec *)&dti->dti_fid,
+		struct dt_insert_rec *rec = &dti->dti_dt_rec;
+
+		rec->rec_fid = &dti->dti_fid;
+		rec->rec_type = dto->do_lu.lo_header->loh_attr;
+		rc = dt_insert(env, parent, (const struct dt_rec *)rec,
 			       (const struct dt_key *)name, th, BYPASS_CAPA, 1);
 		GOTO(unlock, rc);
 	}
@@ -641,9 +670,9 @@ struct local_oid_storage *dt_los_find(struct ls_device *ls, __u64 seq)
 {
 	struct local_oid_storage *los, *ret = NULL;
 
-	cfs_list_for_each_entry(los, &ls->ls_los_list, los_list) {
+	list_for_each_entry(los, &ls->ls_los_list, los_list) {
 		if (los->los_seq == seq) {
-			cfs_atomic_inc(&los->los_refcount);
+			atomic_inc(&los->los_refcount);
 			ret = los;
 			break;
 		}
@@ -653,13 +682,87 @@ struct local_oid_storage *dt_los_find(struct ls_device *ls, __u64 seq)
 
 void dt_los_put(struct local_oid_storage *los)
 {
-	if (cfs_atomic_dec_and_test(&los->los_refcount))
+	if (atomic_dec_and_test(&los->los_refcount))
 		/* should never happen, only local_oid_storage_fini should
 		 * drop refcount to zero */
 		LBUG();
 	return;
 }
 
+/* after Lustre 2.3 release there may be old file to store last generated FID
+ * If such file exists then we have to read its content
+ */
+static int lastid_compat_check(const struct lu_env *env, struct dt_device *dev,
+			       __u64 lastid_seq, __u32 *first_oid,
+			       struct ls_device *ls)
+{
+	struct dt_thread_info	*dti = dt_info(env);
+	struct dt_object	*root = NULL;
+	struct los_ondisk	 losd;
+	struct dt_object	*o = NULL;
+	int			 rc = 0;
+
+	rc = dt_root_get(env, dev, &dti->dti_fid);
+	if (rc)
+		return rc;
+
+	root = ls_locate(env, ls, &dti->dti_fid, NULL);
+	if (IS_ERR(root))
+		return PTR_ERR(root);
+
+	/* find old last_id file */
+	snprintf(dti->dti_buf, sizeof(dti->dti_buf), "seq-"LPX64"-lastid",
+		 lastid_seq);
+	rc = dt_lookup_dir(env, root, dti->dti_buf, &dti->dti_fid);
+	lu_object_put_nocache(env, &root->do_lu);
+	if (rc == -ENOENT) {
+		/* old llog lastid accessed by FID only */
+		if (lastid_seq != FID_SEQ_LLOG)
+			return 0;
+		dti->dti_fid.f_seq = FID_SEQ_LLOG;
+		dti->dti_fid.f_oid = 1;
+		dti->dti_fid.f_ver = 0;
+		o = ls_locate(env, ls, &dti->dti_fid, NULL);
+		if (IS_ERR(o))
+			return PTR_ERR(o);
+
+		if (!dt_object_exists(o)) {
+			lu_object_put_nocache(env, &o->do_lu);
+			return 0;
+		}
+		CDEBUG(D_INFO, "Found old llog lastid file\n");
+	} else if (rc < 0) {
+		return rc;
+	} else {
+		CDEBUG(D_INFO, "Found old lastid file for sequence "LPX64"\n",
+		       lastid_seq);
+		o = ls_locate(env, ls, &dti->dti_fid, NULL);
+		if (IS_ERR(o))
+			return PTR_ERR(o);
+	}
+	/* let's read seq-NNNNNN-lastid file value */
+	LASSERT(dt_object_exists(o));
+	dti->dti_off = 0;
+	dti->dti_lb.lb_buf = &losd;
+	dti->dti_lb.lb_len = sizeof(losd);
+	dt_read_lock(env, o, 0);
+	rc = dt_record_read(env, o, &dti->dti_lb, &dti->dti_off);
+	dt_read_unlock(env, o);
+	if (rc == 0 && le32_to_cpu(losd.lso_magic) != LOS_MAGIC) {
+		CERROR("%s: wrong content of seq-"LPX64"-lastid file, magic %x\n",
+		       o->do_lu.lo_dev->ld_obd->obd_name, lastid_seq,
+		       le32_to_cpu(losd.lso_magic));
+		rc = -EINVAL;
+	} else if (rc < 0) {
+		CERROR("%s: failed to read seq-"LPX64"-lastid: rc = %d\n",
+		       o->do_lu.lo_dev->ld_obd->obd_name, lastid_seq, rc);
+	}
+	lu_object_put_nocache(env, &o->do_lu);
+	if (rc == 0)
+		*first_oid = le32_to_cpu(losd.lso_next_oid);
+	return rc;
+}
+
 /**
  * Initialize local OID storage for required sequence.
  * That may be needed for services that uses local files and requires
@@ -683,11 +786,11 @@ int local_oid_storage_init(const struct lu_env *env, struct dt_device *dev,
 {
 	struct dt_thread_info	*dti = dt_info(env);
 	struct ls_device	*ls;
-	struct los_ondisk	 losd;
-	struct dt_object	*root = NULL;
+	u64			 lastid;
 	struct dt_object	*o = NULL;
 	struct thandle		*th;
-	int			 rc;
+	__u32			 first_oid = fid_oid(first_fid);
+	int			 rc = 0;
 
 	ENTRY;
 
@@ -705,36 +808,27 @@ int local_oid_storage_init(const struct lu_env *env, struct dt_device *dev,
 	if (*los == NULL)
 		GOTO(out, rc = -ENOMEM);
 
-	cfs_atomic_set(&(*los)->los_refcount, 1);
+	atomic_set(&(*los)->los_refcount, 1);
 	mutex_init(&(*los)->los_id_lock);
 	(*los)->los_dev = &ls->ls_top_dev;
-	cfs_atomic_inc(&ls->ls_refcount);
-	cfs_list_add(&(*los)->los_list, &ls->ls_los_list);
-
-	rc = dt_root_get(env, dev, &dti->dti_fid);
-	if (rc)
-		GOTO(out_los, rc);
-
-	root = ls_locate(env, ls, &dti->dti_fid);
-	if (IS_ERR(root))
-		GOTO(out_los, rc = PTR_ERR(root));
-
-	/* initialize data allowing to generate new fids,
-	 * literally we need a sequence */
-	snprintf(dti->dti_buf, sizeof(dti->dti_buf), "seq-%Lx-lastid",
-		 fid_seq(first_fid));
-	rc = dt_lookup_dir(env, root, dti->dti_buf, &dti->dti_fid);
-	if (rc == -ENOENT)
-		dti->dti_fid = *first_fid;
-	else if (rc < 0)
-		GOTO(out_los, rc);
-
-	o = ls_locate(env, ls, &dti->dti_fid);
+	atomic_inc(&ls->ls_refcount);
+	list_add(&(*los)->los_list, &ls->ls_los_list);
+
+	/* Use {seq, 0, 0} to create the LAST_ID file for every
+	 * sequence.  OIDs start at LUSTRE_FID_INIT_OID.
+	 */
+	dti->dti_fid.f_seq = fid_seq(first_fid);
+	dti->dti_fid.f_oid = LUSTRE_FID_LASTID_OID;
+	dti->dti_fid.f_ver = 0;
+	o = ls_locate(env, ls, &dti->dti_fid, NULL);
 	if (IS_ERR(o))
 		GOTO(out_los, rc = PTR_ERR(o));
-	LASSERT(fid_seq(&dti->dti_fid) == fid_seq(first_fid));
+
 	if (!dt_object_exists(o)) {
-		LASSERT(rc == -ENOENT);
+		rc = lastid_compat_check(env, dev, fid_seq(first_fid),
+					 &first_oid, ls);
+		if (rc < 0)
+			GOTO(out_los, rc);
 
 		th = dt_trans_create(env, dev);
 		if (IS_ERR(th))
@@ -749,14 +843,13 @@ int local_oid_storage_init(const struct lu_env *env, struct dt_device *dev,
 		if (rc)
 			GOTO(out_trans, rc);
 
-		rc = dt_declare_insert(env, root,
-				       (const struct dt_rec *)&dti->dti_fid,
-				       (const struct dt_key *)dti->dti_buf,
-				       th);
-		if (rc)
-			GOTO(out_trans, rc);
+		lastid = cpu_to_le64(first_oid);
 
-		rc = dt_declare_record_write(env, o, sizeof(losd), 0, th);
+		dti->dti_off = 0;
+		dti->dti_lb.lb_buf = &lastid;
+		dti->dti_lb.lb_len = sizeof(lastid);
+		rc = dt_declare_record_write(env, o, &dti->dti_lb, dti->dti_off,
+					     th);
 		if (rc)
 			GOTO(out_trans, rc);
 
@@ -764,7 +857,6 @@ int local_oid_storage_init(const struct lu_env *env, struct dt_device *dev,
 		if (rc)
 			GOTO(out_trans, rc);
 
-		dt_write_lock(env, root, 0);
 		dt_write_lock(env, o, 0);
 		if (dt_object_exists(o))
 			GOTO(out_lock, rc = 0);
@@ -774,54 +866,45 @@ int local_oid_storage_init(const struct lu_env *env, struct dt_device *dev,
 		if (rc)
 			GOTO(out_lock, rc);
 
-		losd.lso_magic = cpu_to_le32(LOS_MAGIC);
-		losd.lso_next_oid = cpu_to_le32(fid_oid(first_fid) + 1);
-
-		dti->dti_off = 0;
-		dti->dti_lb.lb_buf = &losd;
-		dti->dti_lb.lb_len = sizeof(losd);
 		rc = dt_record_write(env, o, &dti->dti_lb, &dti->dti_off, th);
 		if (rc)
 			GOTO(out_lock, rc);
-		rc = dt_insert(env, root,
-			       (const struct dt_rec *)&dti->dti_fid,
-			       (const struct dt_key *)dti->dti_buf,
-			       th, BYPASS_CAPA, 1);
-		if (rc)
-			GOTO(out_lock, rc);
 out_lock:
 		dt_write_unlock(env, o);
-		dt_write_unlock(env, root);
 out_trans:
 		dt_trans_stop(env, dev, th);
 	} else {
 		dti->dti_off = 0;
-		dti->dti_lb.lb_buf = &losd;
-		dti->dti_lb.lb_len = sizeof(losd);
+		dti->dti_lb.lb_buf = &lastid;
+		dti->dti_lb.lb_len = sizeof(lastid);
 		dt_read_lock(env, o, 0);
 		rc = dt_record_read(env, o, &dti->dti_lb, &dti->dti_off);
 		dt_read_unlock(env, o);
-		if (rc == 0 && le32_to_cpu(losd.lso_magic) != LOS_MAGIC) {
-			CERROR("local storage file "DFID" is corrupted\n",
-			       PFID(first_fid));
+		if (rc == 0 && le64_to_cpu(lastid) > OBIF_MAX_OID) {
+			CERROR("%s: bad oid "LPU64" is read from LAST_ID\n",
+			       o->do_lu.lo_dev->ld_obd->obd_name,
+			       le64_to_cpu(lastid));
 			rc = -EINVAL;
 		}
 	}
 out_los:
-	if (root != NULL && !IS_ERR(root))
-		lu_object_put_nocache(env, &root->do_lu);
-
 	if (rc != 0) {
-		cfs_list_del(&(*los)->los_list);
-		cfs_atomic_dec(&ls->ls_refcount);
+		list_del(&(*los)->los_list);
+		atomic_dec(&ls->ls_refcount);
 		OBD_FREE_PTR(*los);
 		*los = NULL;
 		if (o != NULL && !IS_ERR(o))
 			lu_object_put_nocache(env, &o->do_lu);
 	} else {
 		(*los)->los_seq = fid_seq(first_fid);
-		(*los)->los_last_oid = le32_to_cpu(losd.lso_next_oid);
+		(*los)->los_last_oid = le64_to_cpu(lastid);
 		(*los)->los_obj = o;
+		/* Read value should not be less than initial one
+		 * but possible after upgrade from older fs.
+		 * In this case just switch to the first_oid in memory and
+		 * it will be updated on disk with first object generated */
+		if ((*los)->los_last_oid < first_oid)
+			(*los)->los_last_oid = first_oid;
 	}
 out:
 	mutex_unlock(&ls->ls_los_mutex);
@@ -831,24 +914,26 @@ out:
 EXPORT_SYMBOL(local_oid_storage_init);
 
 void local_oid_storage_fini(const struct lu_env *env,
-                            struct local_oid_storage *los)
+			    struct local_oid_storage *los)
 {
 	struct ls_device *ls;
 
-	if (!cfs_atomic_dec_and_test(&los->los_refcount))
-		return;
-
 	LASSERT(env);
 	LASSERT(los->los_dev);
 	ls = dt2ls_dev(los->los_dev);
 
+	/* Take the mutex before decreasing the reference to avoid race
+	 * conditions as described in LU-4721. */
 	mutex_lock(&ls->ls_los_mutex);
-	if (cfs_atomic_read(&los->los_refcount) == 0) {
-		if (los->los_obj)
-			lu_object_put_nocache(env, &los->los_obj->do_lu);
-		cfs_list_del(&los->los_list);
-		OBD_FREE_PTR(los);
+	if (!atomic_dec_and_test(&los->los_refcount)) {
+		mutex_unlock(&ls->ls_los_mutex);
+		return;
 	}
+
+	if (los->los_obj)
+		lu_object_put_nocache(env, &los->los_obj->do_lu);
+	list_del(&los->los_list);
+	OBD_FREE_PTR(los);
 	mutex_unlock(&ls->ls_los_mutex);
 	ls_device_put(env, ls);
 }