Initial import

1 files changed, 1007 insertions, 0 deletions

diff --git a/drivers/staging/lustre/lustre/obdclass/llog.c b/drivers/staging/lustre/lustre/obdclass/llog.c
new file mode 100644
index 000000000..114be4a78
--- /dev/null
+++ b/drivers/staging/lustre/lustre/obdclass/llog.c
@@ -0,0 +1,1007 @@
+/*
+ * GPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License version 2 for more details (a copy is included
+ * in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; If not, see
+ * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ * GPL HEADER END
+ */
+/*
+ * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Use is subject to license terms.
+ *
+ * Copyright (c) 2012, Intel Corporation.
+ */
+/*
+ * This file is part of Lustre, http://www.lustre.org/
+ * Lustre is a trademark of Sun Microsystems, Inc.
+ *
+ * lustre/obdclass/llog.c
+ *
+ * OST<->MDS recovery logging infrastructure.
+ * Invariants in implementation:
+ * - we do not share logs among different OST<->MDS connections, so that
+ *   if an OST or MDS fails it need only look at log(s) relevant to itself
+ *
+ * Author: Andreas Dilger <adilger@clusterfs.com>
+ * Author: Alex Zhuravlev <bzzz@whamcloud.com>
+ * Author: Mikhail Pershin <tappro@whamcloud.com>
+ */
+
+#define DEBUG_SUBSYSTEM S_LOG
+
+
+#include "../include/obd_class.h"
+#include "../include/lustre_log.h"
+#include "llog_internal.h"
+
+/*
+ * Allocate a new log or catalog handle
+ * Used inside llog_open().
+ */
+static struct llog_handle *llog_alloc_handle(void)
+{
+	struct llog_handle *loghandle;
+
+	OBD_ALLOC_PTR(loghandle);
+	if (loghandle == NULL)
+		return NULL;
+
+	init_rwsem(&loghandle->lgh_lock);
+	spin_lock_init(&loghandle->lgh_hdr_lock);
+	INIT_LIST_HEAD(&loghandle->u.phd.phd_entry);
+	atomic_set(&loghandle->lgh_refcount, 1);
+
+	return loghandle;
+}
+
+/*
+ * Free llog handle and header data if exists. Used in llog_close() only
+ */
+static void llog_free_handle(struct llog_handle *loghandle)
+{
+	LASSERT(loghandle != NULL);
+
+	/* failed llog_init_handle */
+	if (!loghandle->lgh_hdr)
+		goto out;
+
+	if (loghandle->lgh_hdr->llh_flags & LLOG_F_IS_PLAIN)
+		LASSERT(list_empty(&loghandle->u.phd.phd_entry));
+	else if (loghandle->lgh_hdr->llh_flags & LLOG_F_IS_CAT)
+		LASSERT(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);
+}
+
+void llog_handle_get(struct llog_handle *loghandle)
+{
+	atomic_inc(&loghandle->lgh_refcount);
+}
+
+void llog_handle_put(struct llog_handle *loghandle)
+{
+	LASSERT(atomic_read(&loghandle->lgh_refcount) > 0);
+	if (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(const struct lu_env *env, struct llog_handle *loghandle,
+		    int index)
+{
+	struct llog_log_hdr *llh = loghandle->lgh_hdr;
+	int rc = 0;
+
+	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;
+	}
+
+	spin_lock(&loghandle->lgh_hdr_lock);
+	if (!ext2_clear_bit(index, llh->llh_bitmap)) {
+		spin_unlock(&loghandle->lgh_hdr_lock);
+		CDEBUG(D_RPCTRACE, "Catalog index %u already clear?\n", index);
+		return -ENOENT;
+	}
+
+	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)) {
+		spin_unlock(&loghandle->lgh_hdr_lock);
+		rc = llog_destroy(env, loghandle);
+		if (rc < 0) {
+			CERROR("%s: can't destroy empty llog #"DOSTID
+			       "#%08x: rc = %d\n",
+			       loghandle->lgh_ctxt->loc_obd->obd_name,
+			       POSTID(&loghandle->lgh_id.lgl_oi),
+			       loghandle->lgh_id.lgl_ogen, rc);
+			goto out_err;
+		}
+		return 1;
+	}
+	spin_unlock(&loghandle->lgh_hdr_lock);
+
+	rc = llog_write(env, loghandle, &llh->llh_hdr, NULL, 0, NULL, 0);
+	if (rc < 0) {
+		CERROR("%s: fail to write header for llog #"DOSTID
+		       "#%08x: rc = %d\n",
+		       loghandle->lgh_ctxt->loc_obd->obd_name,
+		       POSTID(&loghandle->lgh_id.lgl_oi),
+		       loghandle->lgh_id.lgl_ogen, rc);
+		goto out_err;
+	}
+	return 0;
+out_err:
+	spin_lock(&loghandle->lgh_hdr_lock);
+	ext2_set_bit(index, llh->llh_bitmap);
+	llh->llh_count++;
+	spin_unlock(&loghandle->lgh_hdr_lock);
+	return rc;
+}
+EXPORT_SYMBOL(llog_cancel_rec);
+
+static int llog_read_header(const struct lu_env *env,
+			    struct llog_handle *handle,
+			    struct obd_uuid *uuid)
+{
+	struct llog_operations *lop;
+	int rc;
+
+	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 = get_seconds();
+		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;
+}
+
+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;
+
+	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");
+			rc = -EINVAL;
+			goto out;
+		} 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");
+			rc = -EINVAL;
+			goto out;
+		}
+		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);
+			rc = -EEXIST;
+			goto out;
+		}
+	}
+	if (flags & LLOG_F_IS_CAT) {
+		LASSERT(list_empty(&handle->u.chd.chd_head));
+		INIT_LIST_HEAD(&handle->u.chd.chd_head);
+		llh->llh_size = sizeof(struct llog_logid_rec);
+	} else if (!(flags & LLOG_F_IS_PLAIN)) {
+		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;
+	}
+	return rc;
+}
+EXPORT_SYMBOL(llog_init_handle);
+
+static int llog_process_thread(void *arg)
+{
+	struct llog_process_info	*lpi = arg;
+	struct llog_handle		*loghandle = lpi->lpi_loghandle;
+	struct llog_log_hdr		*llh = loghandle->lgh_hdr;
+	struct llog_process_cat_data	*cd  = lpi->lpi_catdata;
+	char				*buf;
+	__u64				 cur_offset = LLOG_CHUNK_SIZE;
+	__u64				 last_offset;
+	int				 rc = 0, index = 1, last_index;
+	int				 saved_index = 0;
+	int				 last_called_index = 0;
+
+	LASSERT(llh);
+
+	OBD_ALLOC(buf, LLOG_CHUNK_SIZE);
+	if (!buf) {
+		lpi->lpi_rc = -ENOMEM;
+		return 0;
+	}
+
+	if (cd != NULL) {
+		last_called_index = cd->lpcd_first_idx;
+		index = cd->lpcd_first_idx + 1;
+	}
+	if (cd != NULL && cd->lpcd_last_idx)
+		last_index = cd->lpcd_last_idx;
+	else
+		last_index = LLOG_BITMAP_BYTES * 8 - 1;
+
+	while (rc == 0) {
+		struct llog_rec_hdr *rec;
+
+		/* skip records not set in bitmap */
+		while (index <= last_index &&
+		       !ext2_test_bit(index, llh->llh_bitmap))
+			++index;
+
+		LASSERT(index <= last_index + 1);
+		if (index == last_index + 1)
+			break;
+repeat:
+		CDEBUG(D_OTHER, "index: %d last_index %d\n",
+		       index, last_index);
+
+		/* get the buf with our target record; avoid old garbage */
+		memset(buf, 0, LLOG_CHUNK_SIZE);
+		last_offset = cur_offset;
+		rc = llog_next_block(lpi->lpi_env, loghandle, &saved_index,
+				     index, &cur_offset, buf, LLOG_CHUNK_SIZE);
+		if (rc)
+			goto out;
+
+		/* NB: when rec->lrh_len is accessed it is already swabbed
+		 * since it is used at the "end" of the loop and the rec
+		 * swabbing is done at the beginning of the loop. */
+		for (rec = (struct llog_rec_hdr *)buf;
+		     (char *)rec < buf + LLOG_CHUNK_SIZE;
+		     rec = (struct llog_rec_hdr *)((char *)rec + rec->lrh_len)){
+
+			CDEBUG(D_OTHER, "processing rec 0x%p type %#x\n",
+			       rec, rec->lrh_type);
+
+			if (LLOG_REC_HDR_NEEDS_SWABBING(rec))
+				lustre_swab_llog_rec(rec);
+
+			CDEBUG(D_OTHER, "after swabbing, type=%#x idx=%d\n",
+			       rec->lrh_type, rec->lrh_index);
+
+			if (rec->lrh_index == 0) {
+				/* probably another rec just got added? */
+				rc = 0;
+				if (index <= loghandle->lgh_last_idx)
+					goto repeat;
+				goto out; /* no more records */
+			}
+			if (rec->lrh_len == 0 ||
+			    rec->lrh_len > LLOG_CHUNK_SIZE) {
+				CWARN("invalid length %d in llog record for index %d/%d\n",
+				      rec->lrh_len,
+				      rec->lrh_index, index);
+				rc = -EINVAL;
+				goto out;
+			}
+
+			if (rec->lrh_index < index) {
+				CDEBUG(D_OTHER, "skipping lrh_index %d\n",
+				       rec->lrh_index);
+				continue;
+			}
+
+			CDEBUG(D_OTHER,
+			       "lrh_index: %d lrh_len: %d (%d remains)\n",
+			       rec->lrh_index, rec->lrh_len,
+			       (int)(buf + LLOG_CHUNK_SIZE - (char *)rec));
+
+			loghandle->lgh_cur_idx = rec->lrh_index;
+			loghandle->lgh_cur_offset = (char *)rec - (char *)buf +
+						    last_offset;
+
+			/* if set, process the callback on this record */
+			if (ext2_test_bit(index, llh->llh_bitmap)) {
+				rc = lpi->lpi_cb(lpi->lpi_env, loghandle, rec,
+						 lpi->lpi_cbdata);
+				last_called_index = index;
+				if (rc == LLOG_PROC_BREAK) {
+					goto out;
+				} else if (rc == LLOG_DEL_RECORD) {
+					llog_cancel_rec(lpi->lpi_env,
+							loghandle,
+							rec->lrh_index);
+					rc = 0;
+				}
+				if (rc)
+					goto out;
+			} else {
+				CDEBUG(D_OTHER, "Skipped index %d\n", index);
+			}
+
+			/* next record, still in buffer? */
+			++index;
+			if (index > last_index) {
+				rc = 0;
+				goto out;
+			}
+		}
+	}
+
+out:
+	if (cd != NULL)
+		cd->lpcd_last_idx = last_called_index;
+
+	OBD_FREE(buf, LLOG_CHUNK_SIZE);
+	lpi->lpi_rc = rc;
+	return 0;
+}
+
+static int llog_process_thread_daemonize(void *arg)
+{
+	struct llog_process_info	*lpi = arg;
+	struct lu_env			 env;
+	int				 rc;
+
+	unshare_fs_struct();
+
+	/* client env has no keys, tags is just 0 */
+	rc = lu_env_init(&env, LCT_LOCAL | LCT_MG_THREAD);
+	if (rc)
+		goto out;
+	lpi->lpi_env = &env;
+
+	rc = llog_process_thread(arg);
+
+	lu_env_fini(&env);
+out:
+	complete(&lpi->lpi_completion);
+	return rc;
+}
+
+int llog_process_or_fork(const struct lu_env *env,
+			 struct llog_handle *loghandle,
+			 llog_cb_t cb, void *data, void *catdata, bool fork)
+{
+	struct llog_process_info *lpi;
+	int		      rc;
+
+	OBD_ALLOC_PTR(lpi);
+	if (lpi == NULL) {
+		CERROR("cannot alloc pointer\n");
+		return -ENOMEM;
+	}
+	lpi->lpi_loghandle = loghandle;
+	lpi->lpi_cb	= cb;
+	lpi->lpi_cbdata    = data;
+	lpi->lpi_catdata   = catdata;
+
+	if (fork) {
+		/* The new thread can't use parent env,
+		 * init the new one in llog_process_thread_daemonize. */
+		lpi->lpi_env = NULL;
+		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;
+		}
+		wait_for_completion(&lpi->lpi_completion);
+	} else {
+		lpi->lpi_env = env;
+		llog_process_thread(lpi);
+	}
+	rc = lpi->lpi_rc;
+	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, true);
+}
+EXPORT_SYMBOL(llog_process);
+
+int llog_reverse_process(const struct lu_env *env,
+			 struct llog_handle *loghandle, llog_cb_t cb,
+			 void *data, void *catdata)
+{
+	struct llog_log_hdr *llh = loghandle->lgh_hdr;
+	struct llog_process_cat_data *cd = catdata;
+	void *buf;
+	int rc = 0, first_index = 1, index, idx;
+
+	OBD_ALLOC(buf, LLOG_CHUNK_SIZE);
+	if (!buf)
+		return -ENOMEM;
+
+	if (cd != NULL)
+		first_index = cd->lpcd_first_idx + 1;
+	if (cd != NULL && cd->lpcd_last_idx)
+		index = cd->lpcd_last_idx;
+	else
+		index = LLOG_BITMAP_BYTES * 8 - 1;
+
+	while (rc == 0) {
+		struct llog_rec_hdr *rec;
+		struct llog_rec_tail *tail;
+
+		/* skip records not set in bitmap */
+		while (index >= first_index &&
+		       !ext2_test_bit(index, llh->llh_bitmap))
+			--index;
+
+		LASSERT(index >= first_index - 1);
+		if (index == first_index - 1)
+			break;
+
+		/* get the buf with our target record; avoid old garbage */
+		memset(buf, 0, LLOG_CHUNK_SIZE);
+		rc = llog_prev_block(env, loghandle, index, buf,
+				     LLOG_CHUNK_SIZE);
+		if (rc)
+			goto out;
+
+		rec = buf;
+		idx = rec->lrh_index;
+		CDEBUG(D_RPCTRACE, "index %u : idx %u\n", index, idx);
+		while (idx < index) {
+			rec = (void *)rec + rec->lrh_len;
+			if (LLOG_REC_HDR_NEEDS_SWABBING(rec))
+				lustre_swab_llog_rec(rec);
+			idx ++;
+		}
+		LASSERT(idx == index);
+		tail = (void *)rec + rec->lrh_len - sizeof(*tail);
+
+		/* process records in buffer, starting where we found one */
+		while ((void *)tail > buf) {
+			if (tail->lrt_index == 0) {
+				/* no more records */
+				rc = 0;
+				goto out;
+			}
+
+			/* if set, process the callback on this record */
+			if (ext2_test_bit(index, llh->llh_bitmap)) {
+				rec = (void *)tail - tail->lrt_len +
+				      sizeof(*tail);
+
+				rc = cb(env, loghandle, rec, data);
+				if (rc == LLOG_PROC_BREAK) {
+					goto out;
+				} else if (rc == LLOG_DEL_RECORD) {
+					llog_cancel_rec(env, loghandle,
+							tail->lrt_index);
+					rc = 0;
+				}
+				if (rc)
+					goto out;
+			}
+
+			/* previous record, still in buffer? */
+			--index;
+			if (index < first_index) {
+				rc = 0;
+				goto out;
+			}
+			tail = (void *)tail - tail->lrt_len;
+		}
+	}
+
+out:
+	if (buf)
+		OBD_FREE(buf, LLOG_CHUNK_SIZE);
+	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;
+
+	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;
+
+	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;
+
+	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;
+
+	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;
+
+	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;
+
+	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;
+
+	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;
+
+	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)) {
+		rc = PTR_ERR(th);
+		goto out;
+	}
+
+	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;
+
+	/* 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;
+
+	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 = dt_trans_start_local(env, dt, th);
+	if (rc)
+		goto out_trans;
+
+	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;
+
+	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;
+
+	rc = llog_handle2ops(loghandle, &lop);
+	if (rc)
+		goto out;
+	if (lop->lop_close == NULL) {
+		rc = -EOPNOTSUPP;
+		goto out;
+	}
+	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 = llog_init_handle(env, llh, LLOG_F_IS_PLAIN, NULL);
+	if (rc)
+		goto out_close;
+	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;
+
+
+
+	/* 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;
+
+	/* Make sure there's no old backup log */
+	rc = llog_erase(env, bctxt, NULL, backup);
+	if (rc < 0 && rc != -ENOENT)
+		goto out_close;
+
+	/* 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;
+	}
+
+	/* 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);
+		rc = -EEXIST;
+		goto out_backup;
+	}
+
+	rc = llog_init_handle(env, bllh, LLOG_F_IS_PLAIN, NULL);
+	if (rc)
+		goto out_backup;
+
+	/* 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);