X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=blobdiff_plain;f=lustre%2Fobdclass%2Fllog.c;h=a69023305e054b5c8ef792dd1cfa9d63efe934d7;hp=fdd4a338726b63406bdabc48e6c1e7f145a4eedb;hb=c3d20d0a57e1eebd021ec34323b1223a20e7df16;hpb=3925b3aa87aede47531fdf632e55bfdfb8947957

diff --git a/lustre/obdclass/llog.c b/lustre/obdclass/llog.c
index fdd4a33..a690233 100644
--- a/lustre/obdclass/llog.c
+++ b/lustre/obdclass/llog.c
@@ -26,6 +26,8 @@
 /*
  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
+ *
+ * Copyright (c) 2012, 2013, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
@@ -53,158 +55,213 @@
 #include <lustre_log.h>
 #include "llog_internal.h"
 
-/* Allocate a new log or catalog handle */
+/*
+ * Allocate a new log or catalog handle
+ * Used inside llog_open().
+ */
 struct llog_handle *llog_alloc_handle(void)
 {
-        struct llog_handle *loghandle;
-        ENTRY;
+	struct llog_handle *loghandle;
 
 	OBD_ALLOC_PTR(loghandle);
-        if (loghandle == NULL)
-                RETURN(ERR_PTR(-ENOMEM));
+	if (loghandle == NULL)
+		return NULL;
 
-        cfs_init_rwsem(&loghandle->lgh_lock);
-	cfs_spin_lock_init(&loghandle->lgh_hdr_lock);
+	init_rwsem(&loghandle->lgh_lock);
+	spin_lock_init(&loghandle->lgh_hdr_lock);
 	CFS_INIT_LIST_HEAD(&loghandle->u.phd.phd_entry);
+	cfs_atomic_set(&loghandle->lgh_refcount, 1);
 
-        RETURN(loghandle);
+	return loghandle;
 }
-EXPORT_SYMBOL(llog_alloc_handle);
-
 
+/*
+ * Free llog handle and header data if exists. Used in llog_close() only
+ */
 void llog_free_handle(struct llog_handle *loghandle)
 {
-        if (!loghandle)
-                return;
-
-        if (!loghandle->lgh_hdr)
-                goto out;
-        if (loghandle->lgh_hdr->llh_flags & LLOG_F_IS_PLAIN)
-                cfs_list_del_init(&loghandle->u.phd.phd_entry);
-        if (loghandle->lgh_hdr->llh_flags & LLOG_F_IS_CAT)
-                LASSERT(cfs_list_empty(&loghandle->u.chd.chd_head));
+	LASSERT(loghandle != NULL);
+
+	/* failed llog_init_handle */
+	if (!loghandle->lgh_hdr)
+		goto out;
+
+	if (loghandle->lgh_hdr->llh_flags & LLOG_F_IS_PLAIN)
+		LASSERT(cfs_list_empty(&loghandle->u.phd.phd_entry));
+	else if (loghandle->lgh_hdr->llh_flags & LLOG_F_IS_CAT)
+		LASSERT(cfs_list_empty(&loghandle->u.chd.chd_head));
 	LASSERT(sizeof(*(loghandle->lgh_hdr)) == LLOG_CHUNK_SIZE);
 	OBD_FREE(loghandle->lgh_hdr, LLOG_CHUNK_SIZE);
-
 out:
 	OBD_FREE_PTR(loghandle);
 }
-EXPORT_SYMBOL(llog_free_handle);
+
+void llog_handle_get(struct llog_handle *loghandle)
+{
+	cfs_atomic_inc(&loghandle->lgh_refcount);
+}
+
+void llog_handle_put(struct llog_handle *loghandle)
+{
+	LASSERT(cfs_atomic_read(&loghandle->lgh_refcount) > 0);
+	if (cfs_atomic_dec_and_test(&loghandle->lgh_refcount))
+		llog_free_handle(loghandle);
+}
 
 /* returns negative on error; 0 if success; 1 if success & log destroyed */
-int llog_cancel_rec(struct llog_handle *loghandle, int index)
+int llog_cancel_rec(const struct lu_env *env, struct llog_handle *loghandle,
+		    int index)
 {
         struct llog_log_hdr *llh = loghandle->lgh_hdr;
         int rc = 0;
         ENTRY;
 
-        CDEBUG(D_RPCTRACE, "Canceling %d in log "LPX64"\n",
-               index, loghandle->lgh_id.lgl_oid);
+        CDEBUG(D_RPCTRACE, "Canceling %d in log "DOSTID"\n",
+               index, POSTID(&loghandle->lgh_id.lgl_oi));
 
         if (index == 0) {
                 CERROR("Can't cancel index 0 which is header\n");
                 RETURN(-EINVAL);
         }
 
-	cfs_spin_lock(&loghandle->lgh_hdr_lock);
+	spin_lock(&loghandle->lgh_hdr_lock);
 	if (!ext2_clear_bit(index, llh->llh_bitmap)) {
-		cfs_spin_unlock(&loghandle->lgh_hdr_lock);
-                CDEBUG(D_RPCTRACE, "Catalog index %u already clear?\n", index);
-                RETURN(-ENOENT);
-        }
+		spin_unlock(&loghandle->lgh_hdr_lock);
+		CDEBUG(D_RPCTRACE, "Catalog index %u already clear?\n", index);
+		RETURN(-ENOENT);
+	}
 
-        llh->llh_count--;
+	llh->llh_count--;
 
-        if ((llh->llh_flags & LLOG_F_ZAP_WHEN_EMPTY) &&
-            (llh->llh_count == 1) &&
-            (loghandle->lgh_last_idx == (LLOG_BITMAP_BYTES * 8) - 1)) {
-		cfs_spin_unlock(&loghandle->lgh_hdr_lock);
-		rc = llog_destroy(loghandle);
+	if ((llh->llh_flags & LLOG_F_ZAP_WHEN_EMPTY) &&
+	    (llh->llh_count == 1) &&
+	    (loghandle->lgh_last_idx == (LLOG_BITMAP_BYTES * 8) - 1)) {
+		spin_unlock(&loghandle->lgh_hdr_lock);
+		rc = llog_destroy(env, loghandle);
 		if (rc < 0) {
-			CERROR("%s: can't destroy empty llog #"LPX64"#"LPX64
+			CERROR("%s: can't destroy empty llog #"DOSTID
 			       "#%08x: rc = %d\n",
 			       loghandle->lgh_ctxt->loc_obd->obd_name,
-			       loghandle->lgh_id.lgl_oid,
-			       loghandle->lgh_id.lgl_oseq,
+			       POSTID(&loghandle->lgh_id.lgl_oi),
 			       loghandle->lgh_id.lgl_ogen, rc);
 			GOTO(out_err, rc);
 		}
 		RETURN(1);
 	}
-	cfs_spin_unlock(&loghandle->lgh_hdr_lock);
+	spin_unlock(&loghandle->lgh_hdr_lock);
 
-	rc = llog_write_rec(loghandle, &llh->llh_hdr, NULL, 0, NULL, 0);
+	rc = llog_write(env, loghandle, &llh->llh_hdr, NULL, 0, NULL, 0);
 	if (rc < 0) {
-		CERROR("%s: fail to write header for llog #"LPX64"#"LPX64
+		CERROR("%s: fail to write header for llog #"DOSTID
 		       "#%08x: rc = %d\n",
 		       loghandle->lgh_ctxt->loc_obd->obd_name,
-		       loghandle->lgh_id.lgl_oid,
-		       loghandle->lgh_id.lgl_oseq,
+		       POSTID(&loghandle->lgh_id.lgl_oi),
 		       loghandle->lgh_id.lgl_ogen, rc);
 		GOTO(out_err, rc);
 	}
 	RETURN(0);
 out_err:
-	cfs_spin_lock(&loghandle->lgh_hdr_lock);
+	spin_lock(&loghandle->lgh_hdr_lock);
 	ext2_set_bit(index, llh->llh_bitmap);
 	llh->llh_count++;
-	cfs_spin_unlock(&loghandle->lgh_hdr_lock);
+	spin_unlock(&loghandle->lgh_hdr_lock);
 	return rc;
 }
 EXPORT_SYMBOL(llog_cancel_rec);
 
-int llog_init_handle(struct llog_handle *handle, int flags,
-                     struct obd_uuid *uuid)
+static int llog_read_header(const struct lu_env *env,
+			    struct llog_handle *handle,
+			    struct obd_uuid *uuid)
 {
-        int rc;
-        struct llog_log_hdr *llh;
-        ENTRY;
-        LASSERT(handle->lgh_hdr == NULL);
+	struct llog_operations *lop;
+	int rc;
 
-	OBD_ALLOC_PTR(llh);
-        if (llh == NULL)
-                RETURN(-ENOMEM);
-        handle->lgh_hdr = llh;
-        /* first assign flags to use llog_client_ops */
-        llh->llh_flags = flags;
-        rc = llog_read_header(handle);
-        if (rc == 0) {
-                flags = llh->llh_flags;
-                if (uuid && !obd_uuid_equals(uuid, &llh->llh_tgtuuid)) {
-                        CERROR("uuid mismatch: %s/%s\n", (char *)uuid->uuid,
-                               (char *)llh->llh_tgtuuid.uuid);
-                        rc = -EEXIST;
-                }
-                GOTO(out, rc);
-        } else if (rc != LLOG_EEMPTY || !flags) {
-                /* set a pesudo flag for initialization */
-                flags = LLOG_F_IS_CAT;
-                GOTO(out, rc);
-        }
-        rc = 0;
-
-        handle->lgh_last_idx = 0; /* header is record with index 0 */
-        llh->llh_count = 1;         /* for the header record */
-        llh->llh_hdr.lrh_type = LLOG_HDR_MAGIC;
-        llh->llh_hdr.lrh_len = llh->llh_tail.lrt_len = LLOG_CHUNK_SIZE;
-        llh->llh_hdr.lrh_index = llh->llh_tail.lrt_index = 0;
-        llh->llh_timestamp = cfs_time_current_sec();
-        if (uuid)
-                memcpy(&llh->llh_tgtuuid, uuid, sizeof(llh->llh_tgtuuid));
-        llh->llh_bitmap_offset = offsetof(typeof(*llh),llh_bitmap);
-        ext2_set_bit(0, llh->llh_bitmap);
+	rc = llog_handle2ops(handle, &lop);
+	if (rc)
+		RETURN(rc);
+
+	if (lop->lop_read_header == NULL)
+		RETURN(-EOPNOTSUPP);
+
+	rc = lop->lop_read_header(env, handle);
+	if (rc == LLOG_EEMPTY) {
+		struct llog_log_hdr *llh = handle->lgh_hdr;
+
+		handle->lgh_last_idx = 0; /* header is record with index 0 */
+		llh->llh_count = 1;         /* for the header record */
+		llh->llh_hdr.lrh_type = LLOG_HDR_MAGIC;
+		llh->llh_hdr.lrh_len = llh->llh_tail.lrt_len = LLOG_CHUNK_SIZE;
+		llh->llh_hdr.lrh_index = llh->llh_tail.lrt_index = 0;
+		llh->llh_timestamp = cfs_time_current_sec();
+		if (uuid)
+			memcpy(&llh->llh_tgtuuid, uuid,
+			       sizeof(llh->llh_tgtuuid));
+		llh->llh_bitmap_offset = offsetof(typeof(*llh), llh_bitmap);
+		ext2_set_bit(0, llh->llh_bitmap);
+		rc = 0;
+	}
+	return rc;
+}
 
-out:
-        if (flags & LLOG_F_IS_CAT) {
+int llog_init_handle(const struct lu_env *env, struct llog_handle *handle,
+		     int flags, struct obd_uuid *uuid)
+{
+	struct llog_log_hdr	*llh;
+	int			 rc;
+
+	ENTRY;
+	LASSERT(handle->lgh_hdr == NULL);
+
+	OBD_ALLOC_PTR(llh);
+	if (llh == NULL)
+		RETURN(-ENOMEM);
+	handle->lgh_hdr = llh;
+	/* first assign flags to use llog_client_ops */
+	llh->llh_flags = flags;
+	rc = llog_read_header(env, handle, uuid);
+	if (rc == 0) {
+		if (unlikely((llh->llh_flags & LLOG_F_IS_PLAIN &&
+			      flags & LLOG_F_IS_CAT) ||
+			     (llh->llh_flags & LLOG_F_IS_CAT &&
+			      flags & LLOG_F_IS_PLAIN))) {
+			CERROR("%s: llog type is %s but initializing %s\n",
+			       handle->lgh_ctxt->loc_obd->obd_name,
+			       llh->llh_flags & LLOG_F_IS_CAT ?
+			       "catalog" : "plain",
+			       flags & LLOG_F_IS_CAT ? "catalog" : "plain");
+			GOTO(out, rc = -EINVAL);
+		} else if (llh->llh_flags &
+			   (LLOG_F_IS_PLAIN | LLOG_F_IS_CAT)) {
+			/*
+			 * it is possible to open llog without specifying llog
+			 * type so it is taken from llh_flags
+			 */
+			flags = llh->llh_flags;
+		} else {
+			/* for some reason the llh_flags has no type set */
+			CERROR("llog type is not specified!\n");
+			GOTO(out, rc = -EINVAL);
+		}
+		if (unlikely(uuid &&
+			     !obd_uuid_equals(uuid, &llh->llh_tgtuuid))) {
+			CERROR("%s: llog uuid mismatch: %s/%s\n",
+			       handle->lgh_ctxt->loc_obd->obd_name,
+			       (char *)uuid->uuid,
+			       (char *)llh->llh_tgtuuid.uuid);
+			GOTO(out, rc = -EEXIST);
+		}
+	}
+	if (flags & LLOG_F_IS_CAT) {
 		LASSERT(cfs_list_empty(&handle->u.chd.chd_head));
 		CFS_INIT_LIST_HEAD(&handle->u.chd.chd_head);
 		llh->llh_size = sizeof(struct llog_logid_rec);
 	} else if (!(flags & LLOG_F_IS_PLAIN)) {
-		CERROR("Unknown flags: %#x (Expected %#x or %#x\n",
+		CERROR("%s: unknown flags: %#x (expected %#x or %#x)\n",
+		       handle->lgh_ctxt->loc_obd->obd_name,
 		       flags, LLOG_F_IS_CAT, LLOG_F_IS_PLAIN);
 		rc = -EINVAL;
 	}
-
+out:
 	if (rc) {
 		OBD_FREE_PTR(llh);
 		handle->lgh_hdr = NULL;
@@ -213,24 +270,6 @@ out:
 }
 EXPORT_SYMBOL(llog_init_handle);
 
-int llog_close(struct llog_handle *loghandle)
-{
-        struct llog_operations *lop;
-        int rc;
-        ENTRY;
-
-        rc = llog_handle2ops(loghandle, &lop);
-        if (rc)
-                GOTO(out, rc);
-        if (lop->lop_close == NULL)
-                GOTO(out, -EOPNOTSUPP);
-        rc = lop->lop_close(loghandle);
- out:
-        llog_free_handle(loghandle);
-        RETURN(rc);
-}
-EXPORT_SYMBOL(llog_close);
-
 static int llog_process_thread(void *arg)
 {
 	struct llog_process_info	*lpi = arg;
@@ -281,8 +320,8 @@ repeat:
                 /* get the buf with our target record; avoid old garbage */
                 memset(buf, 0, LLOG_CHUNK_SIZE);
                 last_offset = cur_offset;
-                rc = llog_next_block(loghandle, &saved_index, index,
-                                     &cur_offset, buf, LLOG_CHUNK_SIZE);
+		rc = llog_next_block(lpi->lpi_env, loghandle, &saved_index,
+				     index, &cur_offset, buf, LLOG_CHUNK_SIZE);
                 if (rc)
                         GOTO(out, rc);
 
@@ -333,14 +372,15 @@ repeat:
 
                         /* if set, process the callback on this record */
                         if (ext2_test_bit(index, llh->llh_bitmap)) {
-                                rc = lpi->lpi_cb(loghandle, rec,
-                                                 lpi->lpi_cbdata);
-                                last_called_index = index;
-                                if (rc == LLOG_PROC_BREAK) {
-                                        GOTO(out, rc);
-                                } else if (rc == LLOG_DEL_RECORD) {
-                                        llog_cancel_rec(loghandle,
-                                                        rec->lrh_index);
+				rc = lpi->lpi_cb(lpi->lpi_env, loghandle, rec,
+						 lpi->lpi_cbdata);
+				last_called_index = index;
+				if (rc == LLOG_PROC_BREAK) {
+					GOTO(out, rc);
+				} else if (rc == LLOG_DEL_RECORD) {
+					llog_cancel_rec(lpi->lpi_env,
+							loghandle,
+							rec->lrh_index);
                                         rc = 0;
                                 }
                                 if (rc)
@@ -372,10 +412,10 @@ static int llog_process_thread_daemonize(void *arg)
 	struct lu_env			 env;
 	int				 rc;
 
-	cfs_daemonize_ctxt("llog_process_thread");
+	unshare_fs_struct();
 
 	/* client env has no keys, tags is just 0 */
-	rc = lu_env_init(&env, LCT_LOCAL);
+	rc = lu_env_init(&env, LCT_LOCAL | LCT_MG_THREAD);
 	if (rc)
 		goto out;
 	lpi->lpi_env = &env;
@@ -384,7 +424,7 @@ static int llog_process_thread_daemonize(void *arg)
 
 	lu_env_fini(&env);
 out:
-	cfs_complete(&lpi->lpi_completion);
+	complete(&lpi->lpi_completion);
 	return rc;
 }
 #endif
@@ -413,16 +453,16 @@ int llog_process_or_fork(const struct lu_env *env,
 		/* The new thread can't use parent env,
 		 * init the new one in llog_process_thread_daemonize. */
 		lpi->lpi_env = NULL;
-		cfs_init_completion(&lpi->lpi_completion);
-		rc = cfs_create_thread(llog_process_thread_daemonize, lpi,
-				       CFS_DAEMON_FLAGS);
-		if (rc < 0) {
+		init_completion(&lpi->lpi_completion);
+		rc = PTR_ERR(kthread_run(llog_process_thread_daemonize, lpi,
+					     "llog_process_thread"));
+		if (IS_ERR_VALUE(rc)) {
 			CERROR("%s: cannot start thread: rc = %d\n",
 			       loghandle->lgh_ctxt->loc_obd->obd_name, rc);
 			OBD_FREE_PTR(lpi);
 			RETURN(rc);
 		}
-		cfs_wait_for_completion(&lpi->lpi_completion);
+		wait_for_completion(&lpi->lpi_completion);
 	} else {
 		lpi->lpi_env = env;
 		llog_process_thread(lpi);
@@ -435,22 +475,15 @@ int llog_process_or_fork(const struct lu_env *env,
         OBD_FREE_PTR(lpi);
         RETURN(rc);
 }
+EXPORT_SYMBOL(llog_process_or_fork);
 
 int llog_process(const struct lu_env *env, struct llog_handle *loghandle,
 		 llog_cb_t cb, void *data, void *catdata)
 {
-	return llog_process_or_fork(env, loghandle, cb, data, catdata, false);
+	return llog_process_or_fork(env, loghandle, cb, data, catdata, true);
 }
 EXPORT_SYMBOL(llog_process);
 
-inline int llog_get_size(struct llog_handle *loghandle)
-{
-        if (loghandle && loghandle->lgh_hdr)
-                return loghandle->lgh_hdr->llh_count;
-        return 0;
-}
-EXPORT_SYMBOL(llog_get_size);
-
 int llog_reverse_process(const struct lu_env *env,
 			 struct llog_handle *loghandle, llog_cb_t cb,
 			 void *data, void *catdata)
@@ -487,11 +520,12 @@ int llog_reverse_process(const struct lu_env *env,
 
                 /* get the buf with our target record; avoid old garbage */
                 memset(buf, 0, LLOG_CHUNK_SIZE);
-                rc = llog_prev_block(loghandle, index, buf, LLOG_CHUNK_SIZE);
-                if (rc)
-                        GOTO(out, rc);
+		rc = llog_prev_block(env, loghandle, index, buf,
+				     LLOG_CHUNK_SIZE);
+		if (rc)
+			GOTO(out, rc);
 
-                rec = buf;
+		rec = buf;
 		idx = rec->lrh_index;
 		CDEBUG(D_RPCTRACE, "index %u : idx %u\n", index, idx);
                 while (idx < index) {
@@ -513,11 +547,11 @@ int llog_reverse_process(const struct lu_env *env,
 				rec = (void *)tail - tail->lrt_len +
 				      sizeof(*tail);
 
-                                rc = cb(loghandle, rec, data);
-                                if (rc == LLOG_PROC_BREAK) {
-                                        GOTO(out, rc);
+				rc = cb(env, loghandle, rec, data);
+				if (rc == LLOG_PROC_BREAK) {
+					GOTO(out, rc);
 				} else if (rc == LLOG_DEL_RECORD) {
-					llog_cancel_rec(loghandle,
+					llog_cancel_rec(env, loghandle,
 							tail->lrt_index);
 					rc = 0;
 				}
@@ -539,3 +573,459 @@ out:
         RETURN(rc);
 }
 EXPORT_SYMBOL(llog_reverse_process);
+
+/**
+ * new llog API
+ *
+ * API functions:
+ *      llog_open - open llog, may not exist
+ *      llog_exist - check if llog exists
+ *      llog_close - close opened llog, pair for open, frees llog_handle
+ *      llog_declare_create - declare llog creation
+ *      llog_create - create new llog on disk, need transaction handle
+ *      llog_declare_write_rec - declaration of llog write
+ *      llog_write_rec - write llog record on disk, need transaction handle
+ *      llog_declare_add - declare llog catalog record addition
+ *      llog_add - add llog record in catalog, need transaction handle
+ */
+int llog_exist(struct llog_handle *loghandle)
+{
+	struct llog_operations	*lop;
+	int			 rc;
+
+	ENTRY;
+
+	rc = llog_handle2ops(loghandle, &lop);
+	if (rc)
+		RETURN(rc);
+	if (lop->lop_exist == NULL)
+		RETURN(-EOPNOTSUPP);
+
+	rc = lop->lop_exist(loghandle);
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_exist);
+
+int llog_declare_create(const struct lu_env *env,
+			struct llog_handle *loghandle, struct thandle *th)
+{
+	struct llog_operations	*lop;
+	int			 raised, rc;
+
+	ENTRY;
+
+	rc = llog_handle2ops(loghandle, &lop);
+	if (rc)
+		RETURN(rc);
+	if (lop->lop_declare_create == NULL)
+		RETURN(-EOPNOTSUPP);
+
+	raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
+	if (!raised)
+		cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+	rc = lop->lop_declare_create(env, loghandle, th);
+	if (!raised)
+		cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_declare_create);
+
+int llog_create(const struct lu_env *env, struct llog_handle *handle,
+		struct thandle *th)
+{
+	struct llog_operations	*lop;
+	int			 raised, rc;
+
+	ENTRY;
+
+	rc = llog_handle2ops(handle, &lop);
+	if (rc)
+		RETURN(rc);
+	if (lop->lop_create == NULL)
+		RETURN(-EOPNOTSUPP);
+
+	raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
+	if (!raised)
+		cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+	rc = lop->lop_create(env, handle, th);
+	if (!raised)
+		cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_create);
+
+int llog_declare_write_rec(const struct lu_env *env,
+			   struct llog_handle *handle,
+			   struct llog_rec_hdr *rec, int idx,
+			   struct thandle *th)
+{
+	struct llog_operations	*lop;
+	int			 raised, rc;
+
+	ENTRY;
+
+	rc = llog_handle2ops(handle, &lop);
+	if (rc)
+		RETURN(rc);
+	LASSERT(lop);
+	if (lop->lop_declare_write_rec == NULL)
+		RETURN(-EOPNOTSUPP);
+
+	raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
+	if (!raised)
+		cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+	rc = lop->lop_declare_write_rec(env, handle, rec, idx, th);
+	if (!raised)
+		cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_declare_write_rec);
+
+int llog_write_rec(const struct lu_env *env, struct llog_handle *handle,
+		   struct llog_rec_hdr *rec, struct llog_cookie *logcookies,
+		   int numcookies, void *buf, int idx, struct thandle *th)
+{
+	struct llog_operations	*lop;
+	int			 raised, rc, buflen;
+
+	ENTRY;
+
+	rc = llog_handle2ops(handle, &lop);
+	if (rc)
+		RETURN(rc);
+
+	LASSERT(lop);
+	if (lop->lop_write_rec == NULL)
+		RETURN(-EOPNOTSUPP);
+
+	if (buf)
+		buflen = rec->lrh_len + sizeof(struct llog_rec_hdr) +
+			 sizeof(struct llog_rec_tail);
+	else
+		buflen = rec->lrh_len;
+	LASSERT(cfs_size_round(buflen) == buflen);
+
+	raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
+	if (!raised)
+		cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+	rc = lop->lop_write_rec(env, handle, rec, logcookies, numcookies,
+				buf, idx, th);
+	if (!raised)
+		cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_write_rec);
+
+int llog_add(const struct lu_env *env, struct llog_handle *lgh,
+	     struct llog_rec_hdr *rec, struct llog_cookie *logcookies,
+	     void *buf, struct thandle *th)
+{
+	int raised, rc;
+
+	ENTRY;
+
+	if (lgh->lgh_logops->lop_add == NULL)
+		RETURN(-EOPNOTSUPP);
+
+	raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
+	if (!raised)
+		cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+	rc = lgh->lgh_logops->lop_add(env, lgh, rec, logcookies, buf, th);
+	if (!raised)
+		cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_add);
+
+int llog_declare_add(const struct lu_env *env, struct llog_handle *lgh,
+		     struct llog_rec_hdr *rec, struct thandle *th)
+{
+	int raised, rc;
+
+	ENTRY;
+
+	if (lgh->lgh_logops->lop_declare_add == NULL)
+		RETURN(-EOPNOTSUPP);
+
+	raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
+	if (!raised)
+		cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+	rc = lgh->lgh_logops->lop_declare_add(env, lgh, rec, th);
+	if (!raised)
+		cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_declare_add);
+
+/**
+ * Helper function to open llog or create it if doesn't exist.
+ * It hides all transaction handling from caller.
+ */
+int llog_open_create(const struct lu_env *env, struct llog_ctxt *ctxt,
+		     struct llog_handle **res, struct llog_logid *logid,
+		     char *name)
+{
+	struct dt_device	*d;
+	struct thandle		*th;
+	int			 rc;
+
+	ENTRY;
+
+	rc = llog_open(env, ctxt, res, logid, name, LLOG_OPEN_NEW);
+	if (rc)
+		RETURN(rc);
+
+	if (llog_exist(*res))
+		RETURN(0);
+
+	LASSERT((*res)->lgh_obj != NULL);
+
+	d = lu2dt_dev((*res)->lgh_obj->do_lu.lo_dev);
+
+	th = dt_trans_create(env, d);
+	if (IS_ERR(th))
+		GOTO(out, rc = PTR_ERR(th));
+
+	rc = llog_declare_create(env, *res, th);
+	if (rc == 0) {
+		rc = dt_trans_start_local(env, d, th);
+		if (rc == 0)
+			rc = llog_create(env, *res, th);
+	}
+	dt_trans_stop(env, d, th);
+out:
+	if (rc)
+		llog_close(env, *res);
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_open_create);
+
+/**
+ * Helper function to delete existent llog.
+ */
+int llog_erase(const struct lu_env *env, struct llog_ctxt *ctxt,
+	       struct llog_logid *logid, char *name)
+{
+	struct llog_handle	*handle;
+	int			 rc = 0, rc2;
+
+	ENTRY;
+
+	/* nothing to erase */
+	if (name == NULL && logid == NULL)
+		RETURN(0);
+
+	rc = llog_open(env, ctxt, &handle, logid, name, LLOG_OPEN_EXISTS);
+	if (rc < 0)
+		RETURN(rc);
+
+	rc = llog_init_handle(env, handle, LLOG_F_IS_PLAIN, NULL);
+	if (rc == 0)
+		rc = llog_destroy(env, handle);
+
+	rc2 = llog_close(env, handle);
+	if (rc == 0)
+		rc = rc2;
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_erase);
+
+/*
+ * Helper function for write record in llog.
+ * It hides all transaction handling from caller.
+ * Valid only with local llog.
+ */
+int llog_write(const struct lu_env *env, struct llog_handle *loghandle,
+	       struct llog_rec_hdr *rec, struct llog_cookie *reccookie,
+	       int cookiecount, void *buf, int idx)
+{
+	struct dt_device	*dt;
+	struct thandle		*th;
+	int			 rc;
+
+	ENTRY;
+
+	LASSERT(loghandle);
+	LASSERT(loghandle->lgh_ctxt);
+	LASSERT(loghandle->lgh_obj != NULL);
+
+	dt = lu2dt_dev(loghandle->lgh_obj->do_lu.lo_dev);
+
+	th = dt_trans_create(env, dt);
+	if (IS_ERR(th))
+		RETURN(PTR_ERR(th));
+
+	rc = llog_declare_write_rec(env, loghandle, rec, idx, th);
+	if (rc)
+		GOTO(out_trans, rc);
+
+	rc = dt_trans_start_local(env, dt, th);
+	if (rc)
+		GOTO(out_trans, rc);
+
+	down_write(&loghandle->lgh_lock);
+	rc = llog_write_rec(env, loghandle, rec, reccookie,
+			    cookiecount, buf, idx, th);
+	up_write(&loghandle->lgh_lock);
+out_trans:
+	dt_trans_stop(env, dt, th);
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_write);
+
+int llog_open(const struct lu_env *env, struct llog_ctxt *ctxt,
+	      struct llog_handle **lgh, struct llog_logid *logid,
+	      char *name, enum llog_open_param open_param)
+{
+	int	 raised;
+	int	 rc;
+
+	ENTRY;
+
+	LASSERT(ctxt);
+	LASSERT(ctxt->loc_logops);
+
+	if (ctxt->loc_logops->lop_open == NULL) {
+		*lgh = NULL;
+		RETURN(-EOPNOTSUPP);
+	}
+
+	*lgh = llog_alloc_handle();
+	if (*lgh == NULL)
+		RETURN(-ENOMEM);
+	(*lgh)->lgh_ctxt = ctxt;
+	(*lgh)->lgh_logops = ctxt->loc_logops;
+
+	raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
+	if (!raised)
+		cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+	rc = ctxt->loc_logops->lop_open(env, *lgh, logid, name, open_param);
+	if (!raised)
+		cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+	if (rc) {
+		llog_free_handle(*lgh);
+		*lgh = NULL;
+	}
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_open);
+
+int llog_close(const struct lu_env *env, struct llog_handle *loghandle)
+{
+	struct llog_operations	*lop;
+	int			 rc;
+
+	ENTRY;
+
+	rc = llog_handle2ops(loghandle, &lop);
+	if (rc)
+		GOTO(out, rc);
+	if (lop->lop_close == NULL)
+		GOTO(out, rc = -EOPNOTSUPP);
+	rc = lop->lop_close(env, loghandle);
+out:
+	llog_handle_put(loghandle);
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_close);
+
+int llog_is_empty(const struct lu_env *env, struct llog_ctxt *ctxt,
+		  char *name)
+{
+	struct llog_handle	*llh;
+	int			 rc = 0;
+
+	rc = llog_open(env, ctxt, &llh, NULL, name, LLOG_OPEN_EXISTS);
+	if (rc < 0) {
+		if (likely(rc == -ENOENT))
+			rc = 0;
+		GOTO(out, rc);
+	}
+
+	rc = llog_init_handle(env, llh, LLOG_F_IS_PLAIN, NULL);
+	if (rc)
+		GOTO(out_close, rc);
+	rc = llog_get_size(llh);
+
+out_close:
+	llog_close(env, llh);
+out:
+	/* header is record 1 */
+	return (rc <= 1);
+}
+EXPORT_SYMBOL(llog_is_empty);
+
+int llog_copy_handler(const struct lu_env *env, struct llog_handle *llh,
+		      struct llog_rec_hdr *rec, void *data)
+{
+	struct llog_handle	*copy_llh = data;
+
+	/* Append all records */
+	return llog_write(env, copy_llh, rec, NULL, 0, NULL, -1);
+}
+EXPORT_SYMBOL(llog_copy_handler);
+
+/* backup plain llog */
+int llog_backup(const struct lu_env *env, struct obd_device *obd,
+		struct llog_ctxt *ctxt, struct llog_ctxt *bctxt,
+		char *name, char *backup)
+{
+	struct llog_handle	*llh, *bllh;
+	int			 rc;
+
+	ENTRY;
+
+	/* open original log */
+	rc = llog_open(env, ctxt, &llh, NULL, name, LLOG_OPEN_EXISTS);
+	if (rc < 0) {
+		/* the -ENOENT case is also reported to the caller
+		 * but silently so it should handle that if needed.
+		 */
+		if (rc != -ENOENT)
+			CERROR("%s: failed to open log %s: rc = %d\n",
+			       obd->obd_name, name, rc);
+		RETURN(rc);
+	}
+
+	rc = llog_init_handle(env, llh, LLOG_F_IS_PLAIN, NULL);
+	if (rc)
+		GOTO(out_close, rc);
+
+	/* Make sure there's no old backup log */
+	rc = llog_erase(env, bctxt, NULL, backup);
+	if (rc < 0 && rc != -ENOENT)
+		GOTO(out_close, rc);
+
+	/* open backup log */
+	rc = llog_open_create(env, bctxt, &bllh, NULL, backup);
+	if (rc) {
+		CERROR("%s: failed to open backup logfile %s: rc = %d\n",
+		       obd->obd_name, backup, rc);
+		GOTO(out_close, rc);
+	}
+
+	/* check that backup llog is not the same object as original one */
+	if (llh->lgh_obj == bllh->lgh_obj) {
+		CERROR("%s: backup llog %s to itself (%s), objects %p/%p\n",
+		       obd->obd_name, name, backup, llh->lgh_obj,
+		       bllh->lgh_obj);
+		GOTO(out_backup, rc = -EEXIST);
+	}
+
+	rc = llog_init_handle(env, bllh, LLOG_F_IS_PLAIN, NULL);
+	if (rc)
+		GOTO(out_backup, rc);
+
+	/* Copy log record by record */
+	rc = llog_process_or_fork(env, llh, llog_copy_handler, (void *)bllh,
+				  NULL, false);
+	if (rc)
+		CERROR("%s: failed to backup log %s: rc = %d\n",
+		       obd->obd_name, name, rc);
+out_backup:
+	llog_close(env, bllh);
+out_close:
+	llog_close(env, llh);
+	RETURN(rc);
+}
+EXPORT_SYMBOL(llog_backup);