// SPDX-License-Identifier: GPL-2.0

/*
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2012, 2017, Intel Corporation.
 */

/*
 * This file is part of Lustre, http://www.lustre.org/
 *
 * 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 <linux/fs_struct.h>
#include <linux/pid_namespace.h>
#include <linux/kthread.h>
#include <llog_swab.h>
#include <lustre_log.h>
#include <obd_support.h>
#include <obd_class.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_rwsem(&loghandle->lgh_last_sem);
	INIT_LIST_HEAD(&loghandle->u.phd.phd_entry);
	refcount_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 == NULL)
		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));
	OBD_FREE_LARGE(loghandle->lgh_hdr, loghandle->lgh_hdr_size);
out:
	OBD_FREE_PTR(loghandle);
}

struct llog_handle *llog_handle_get(struct llog_handle *loghandle)
{
	if (refcount_inc_not_zero(&loghandle->lgh_refcount))
		return loghandle;
	return NULL;
}

int llog_handle_put(const struct lu_env *env, struct llog_handle *loghandle)
{
	int rc = 0;

	if (refcount_dec_and_test(&loghandle->lgh_refcount)) {
		const struct llog_operations *lop;

		rc = llog_handle2ops(loghandle, &lop);
		if (!rc) {
			if (lop->lop_close)
				rc = lop->lop_close(env, loghandle);
			else
				rc = -EOPNOTSUPP;
		}
		llog_free_handle(loghandle);
	}
	return rc;
}

static int llog_declare_destroy(const struct lu_env *env,
				struct llog_handle *handle,
				struct thandle *th)
{
	const struct llog_operations *lop;
	int rc;

	ENTRY;

	rc = llog_handle2ops(handle, &lop);
	if (rc)
		RETURN(rc);
	if (lop->lop_declare_destroy == NULL)
		RETURN(-EOPNOTSUPP);

	rc = lop->lop_declare_destroy(env, handle, th);

	RETURN(rc);
}

int llog_trans_destroy(const struct lu_env *env, struct llog_handle *handle,
		       struct thandle *th)
{
	const struct llog_operations *lop;
	int rc;
	ENTRY;

	rc = llog_handle2ops(handle, &lop);
	if (rc < 0)
		RETURN(rc);
	if (lop->lop_destroy == NULL)
		RETURN(-EOPNOTSUPP);

	LASSERT(handle->lgh_obj != NULL);
	if (!llog_exist(handle))
		RETURN(0);

	rc = lop->lop_destroy(env, handle, th);

	RETURN(rc);
}

int llog_destroy(const struct lu_env *env, struct llog_handle *handle)
{
	const struct llog_operations *lop;
	struct dt_device *dt;
	struct thandle *th;
	int rc;

	ENTRY;

	rc = llog_handle2ops(handle, &lop);
	if (rc < 0)
		RETURN(rc);
	if (lop->lop_destroy == NULL)
		RETURN(-EOPNOTSUPP);

	if (handle->lgh_obj == NULL) {
		/* if lgh_obj == NULL, then it is from client side destroy */
		rc = lop->lop_destroy(env, handle, NULL);
		RETURN(rc);
	}

	if (!llog_exist(handle))
		RETURN(0);

	dt = lu2dt_dev(handle->lgh_obj->do_lu.lo_dev);

	if (unlikely(unlikely(dt->dd_rdonly)))
		RETURN(-EROFS);

	th = dt_trans_create(env, dt);
	if (IS_ERR(th))
		RETURN(PTR_ERR(th));
	th->th_wait_submit = 1;

	rc = llog_declare_destroy(env, handle, th);
	if (rc != 0)
		GOTO(out_trans, rc);

	rc = dt_trans_start_local(env, dt, th);
	if (rc < 0)
		GOTO(out_trans, rc);

	rc = lop->lop_destroy(env, handle, th);

out_trans:
	dt_trans_stop(env, dt, th);

	RETURN(rc);
}
EXPORT_SYMBOL(llog_destroy);

/* returns negative on error; 0 if success; 1 if success & log destroyed */
int llog_cancel_arr_rec(const struct lu_env *env, struct llog_handle *loghandle,
			int num, int *index)
{
	struct llog_thread_info *lgi = llog_info(env);
	struct dt_device	*dt;
	struct llog_log_hdr	*llh;
	struct thandle		*th;
	__u32			 tmp_lgc_index;
	int			 old_cat = -1;
	int			 rc, i = 0;
	int rc1;
	bool subtract_count = false;

	ENTRY;

	LASSERT(loghandle != NULL);
	LASSERT(loghandle->lgh_ctxt != NULL);
	LASSERT(loghandle->lgh_obj != NULL);

	llh = loghandle->lgh_hdr;

	CDEBUG(D_OTHER, "Canceling %d records, first %d in log "DFID"\n",
	       num, index[0], PLOGID(&loghandle->lgh_id));

	dt = lu2dt_dev(loghandle->lgh_obj->do_lu.lo_dev);

	if (unlikely(unlikely(dt->dd_rdonly)))
		RETURN(0);

	th = dt_trans_create(env, dt);
	if (IS_ERR(th))
		RETURN(PTR_ERR(th));

	rc = llog_declare_write_rec(env, loghandle, &llh->llh_hdr, 0, th);
	if (rc < 0)
		GOTO(out_trans, rc);

	if ((llh->llh_flags & LLOG_F_ZAP_WHEN_EMPTY)) {
		rc = llog_declare_destroy(env, loghandle, th);
		if (rc < 0)
			GOTO(out_trans, rc);
	}
	if (llh->llh_flags & LLOG_F_IS_CAT)
		dt_declare_attr_set(env, loghandle->lgh_obj, NULL, th);

	th->th_wait_submit = 1;
	rc = dt_trans_start_local(env, dt, th);
	if (rc < 0)
		GOTO(out_trans, rc);

	down_write(&loghandle->lgh_lock);
	/* clear bitmap */
	spin_lock(&loghandle->lgh_hdr_lock);
	for (i = 0; i < num; ++i) {
		if (index[i] == 0) {
			spin_unlock(&loghandle->lgh_hdr_lock);
			CERROR("Can't cancel index 0 which is header\n");
			GOTO(out_unlock, rc = -EINVAL);
		}
		if (!__test_and_clear_bit_le(index[i], LLOG_HDR_BITMAP(llh))) {
			spin_unlock(&loghandle->lgh_hdr_lock);
			CDEBUG(D_OTHER, "Catalog index %u already clear?\n",
			       index[i]);
			GOTO(out_unlock, rc = -ENOENT);
		}
	}
	loghandle->lgh_hdr->llh_count -= num;
	subtract_count = true;
	spin_unlock(&loghandle->lgh_hdr_lock);

	if (llh->llh_flags & LLOG_F_IS_CAT) {
		old_cat = llh->llh_cat_idx;
		llog_cat_set_first_idx(loghandle, index[0]);
	}
	/* Since llog_process_thread use lgi_cookie, it`s better to save them
	 * and restore after using
	 */
	tmp_lgc_index = lgi->lgi_cookie.lgc_index;
	/* Pass this index to llog_osd_write_rec(), which will use the index
	 * to only update the necesary bitmap. */
	lgi->lgi_cookie.lgc_index = index[0];
	/* update header */
	rc = llog_write_rec(env, loghandle, &llh->llh_hdr, (num != 1 ? NULL :
			    &lgi->lgi_cookie), LLOG_HEADER_IDX, th);
	lgi->lgi_cookie.lgc_index = tmp_lgc_index;

	if (rc != 0)
		GOTO(out_unlock, rc);

	if ((llh->llh_flags & LLOG_F_ZAP_WHEN_EMPTY) &&
	    (llh->llh_count == 1) &&
	    ((loghandle->lgh_last_idx == llog_max_idx(llh)) ||
	     (loghandle->u.phd.phd_cat_handle != NULL &&
	      loghandle->u.phd.phd_cat_handle->u.chd.chd_current_log !=
		loghandle))) {
		/* never try to destroy it again */
		llh->llh_flags &= ~LLOG_F_ZAP_WHEN_EMPTY;
		rc = llog_trans_destroy(env, loghandle, th);
		if (rc < 0) {
			/* Sigh, can not destroy the final plain llog, but
			 * the bitmap has been clearly, so the record can not
			 * be accessed anymore, let's return 0 for now, and
			 * the orphan will be handled by LFSCK. */
			CERROR("%s: can't destroy empty llog "DFID": rc = %d\n",
			       loghandle2name(loghandle),
			       PLOGID(&loghandle->lgh_id), rc);
			GOTO(out_unlock, rc = 0);
		}
		rc = LLOG_DEL_PLAIN;
	}

	/* update for catalog which doesn't happen very often */
	if (llh->llh_flags & LLOG_F_IS_CAT) {
		lgi->lgi_attr.la_valid = LA_MTIME;
		lgi->lgi_attr.la_mtime = ktime_get_real_seconds();
		dt_attr_set(env, loghandle->lgh_obj, &lgi->lgi_attr, th);
	}

out_unlock:
	if (rc < 0) {
		if (old_cat != -1) {
			llh->llh_cat_idx = old_cat;
			old_cat = -1;
		}
		/* restore bitmap while holding a mutex */
		spin_lock(&loghandle->lgh_hdr_lock);
		if (subtract_count) {
			loghandle->lgh_hdr->llh_count += num;
			subtract_count = false;
		}
		for (i = i - 1; i >= 0; i--)
			set_bit_le(index[i], LLOG_HDR_BITMAP(llh));
		spin_unlock(&loghandle->lgh_hdr_lock);
	}
	up_write(&loghandle->lgh_lock);
out_trans:
	rc1 = dt_trans_stop(env, dt, th);
	if (rc == 0)
		rc = rc1;
	if (rc1 < 0) {
		if (old_cat != -1)
			llh->llh_cat_idx = old_cat;
		spin_lock(&loghandle->lgh_hdr_lock);
		if (subtract_count)
			loghandle->lgh_hdr->llh_count += num;
		for (i = i - 1; i >= 0; i--)
			set_bit_le(index[i], LLOG_HDR_BITMAP(llh));
		spin_unlock(&loghandle->lgh_hdr_lock);
	}
	RETURN(rc);
}

int llog_cancel_rec(const struct lu_env *env, struct llog_handle *loghandle,
		    int index)
{
	return llog_cancel_arr_rec(env, loghandle, 1, &index);
}

int llog_read_header(const struct lu_env *env, struct llog_handle *handle,
		     const struct obd_uuid *uuid)
{
	const struct llog_operations *lop;
	int rc;
	ENTRY;

	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;

		/* lrh_len should be initialized in llog_init_handle */
		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;
		LASSERT(handle->lgh_ctxt->loc_chunk_size >=
						LLOG_MIN_CHUNK_SIZE);
		llh->llh_hdr.lrh_len = handle->lgh_ctxt->loc_chunk_size;
		llh->llh_hdr.lrh_index = 0;
		llh->llh_timestamp = ktime_get_real_seconds();
		if (uuid)
			memcpy(&llh->llh_tgtuuid, uuid,
			       sizeof(llh->llh_tgtuuid));
		llh->llh_bitmap_offset = offsetof(typeof(*llh), llh_bitmap);
		/* Since update llog header might also call this function,
		 * let's reset the bitmap to 0 here */
		memset(LLOG_HDR_BITMAP(llh), 0, llh->llh_hdr.lrh_len -
						llh->llh_bitmap_offset -
						sizeof(llh->llh_tail));
		set_bit_le(0, LLOG_HDR_BITMAP(llh));
		LLOG_HDR_TAIL(llh)->lrt_len = llh->llh_hdr.lrh_len;
		LLOG_HDR_TAIL(llh)->lrt_index = llh->llh_hdr.lrh_index;
		handle->lgh_cur_offset = llh->llh_hdr.lrh_len;
		rc = 0;
	}
	RETURN(rc);
}
EXPORT_SYMBOL(llog_read_header);

int llog_init_handle(const struct lu_env *env, struct llog_handle *handle,
		     int flags, struct obd_uuid *uuid)
{
	struct llog_log_hdr *llh;
	enum llog_flag fmt = flags & LLOG_F_EXT_MASK;
	int rc;
	int chunk_size = handle->lgh_ctxt->loc_chunk_size;

	ENTRY;

	LASSERT(handle->lgh_hdr == NULL);

	LASSERT(chunk_size >= LLOG_MIN_CHUNK_SIZE);
	OBD_ALLOC_LARGE(llh, chunk_size);
	if (llh == NULL)
		RETURN(-ENOMEM);

	handle->lgh_hdr = llh;
	handle->lgh_hdr_size = chunk_size;
	/* 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",
			       loghandle2name(handle),
			       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",
			       loghandle2name(handle),
			       (char *)uuid->uuid,
			       (char *)llh->llh_tgtuuid.uuid);
			GOTO(out, rc = -EINVAL);
		}
	}
	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);
		llh->llh_flags |= LLOG_F_IS_FIXSIZE;
		/* Fixing llh_cat_idx if it has problem */
		if (rc == 0)
			llog_cat_set_first_idx(handle, llh->llh_cat_idx);
	} else if (!(flags & LLOG_F_IS_PLAIN)) {
		CERROR("%s: unknown flags: %#x (expected %#x or %#x)\n",
		       loghandle2name(handle), flags, LLOG_F_IS_CAT,
		       LLOG_F_IS_PLAIN);
		rc = -EINVAL;
	}
	llh->llh_flags |= fmt;
out:
	if (rc) {
		OBD_FREE_LARGE(llh, chunk_size);
		handle->lgh_hdr = NULL;
	}
	RETURN(rc);
}
EXPORT_SYMBOL(llog_init_handle);

#define LLOG_ERROR_REC(lgh, rec, format, a...) \
	CDEBUG(D_OTHER, "%s: "DFID" rec type=%x idx=%u len=%u, " format "\n", \
	       loghandle2name(lgh), PLOGID(&lgh->lgh_id), (rec)->lrh_type, \
	       (rec)->lrh_index, (rec)->lrh_len, ##a)

int llog_verify_record(const struct llog_handle *llh, struct llog_rec_hdr *rec)
{
	int chunk_size = llh->lgh_hdr->llh_hdr.lrh_len;

	if ((rec->lrh_type & LLOG_OP_MASK) != LLOG_OP_MAGIC)
		LLOG_ERROR_REC(llh, rec, "magic is bad");
	else if (rec->lrh_len == 0 || rec->lrh_len > chunk_size ||
		 rec->lrh_len < LLOG_MIN_REC_SIZE)
		LLOG_ERROR_REC(llh, rec, "bad record len, chunk size is %d",
			       chunk_size);
	else if (rec->lrh_index > llog_max_idx(llh->lgh_hdr))
		LLOG_ERROR_REC(llh, rec, "index is too high");
	else
		return 0;

	return -EINVAL;
}
EXPORT_SYMBOL(llog_verify_record);

static inline bool llog_is_index_skipable(int idx, struct llog_log_hdr *llh,
					  struct llog_process_cat_data *cd)
{
	if (cd && (cd->lpcd_read_mode & LLOG_READ_MODE_RAW))
		return false;

	return !test_bit_le(idx, LLOG_HDR_BITMAP(llh));
}

static inline int llog_skip_gap(struct llog_rec_hdr *start, char *end)
{
	struct llog_rec_hdr *rec = start;

	/* skipping zero gap */
	while ((rec->lrh_index == 0 || rec->lrh_len == 0) &&
	       (char *)rec < (char *)end)
		rec = (typeof(rec))(((char *)rec) + 4);

	if ((char *)rec > end ||
	    !((rec->lrh_type & LLOG_OP_MASK) == LLOG_OP_MAGIC ||
	      ((rec->lrh_type & __swab32(LLOG_OP_MASK)) ==
	       __swab32(LLOG_OP_MAGIC))))
		return -ENOENT;

	return (int)((char *)rec - (char *)start);
}

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;
	struct llog_thread_info *lti;
	char *buf;
	size_t chunk_size;
	__u64 cur_offset;
	int rc = 0, index = 1, last_index;
	int saved_index = 0;
	int last_called_index = 0;
	bool repeated = false;
	struct lu_env *env = NULL, _env;

	ENTRY;

	if (llh == NULL)
		RETURN(-EINVAL);

	/*
	 * this can be called as a separate thread processing llog or
	 * as a part of more functional thread like osp sync thread with
	 * an existing env
	 */
	env = lu_env_find();
	if (env == NULL) {
		rc = lu_env_init(&_env, LCT_DT_THREAD | LCT_MD_THREAD);
		if (rc)
			RETURN(rc);
		env = &_env;
		rc = lu_env_add(&_env);
		if (unlikely(rc))
			GOTO(out_fini, rc);
	}
	lti = llog_info(env);

	cur_offset = chunk_size = llh->llh_hdr.lrh_len;
	/* expect chunk_size to be power of two */
	LASSERT(is_power_of_2(chunk_size));

	OBD_ALLOC_LARGE(buf, chunk_size);
	if (unlikely(buf == NULL))
		GOTO(out_env, rc = -ENOMEM);

	last_index = llog_max_idx(llh);
	if (cd) {
		if (cd->lpcd_first_idx >= llog_max_idx(llh))
			/* End of the indexes -> Nothing to do */
			GOTO(out, rc = 0);

		index = cd->lpcd_first_idx + 1;
		last_called_index = cd->lpcd_first_idx;
		if (cd->lpcd_last_idx > 0 &&
		    cd->lpcd_last_idx <= llog_max_idx(llh))
			last_index = cd->lpcd_last_idx;
		else if (cd->lpcd_read_mode & LLOG_READ_MODE_RAW)
			last_index = loghandle->lgh_last_idx;
	}

	while (rc == 0) {
		struct llog_rec_hdr *rec;
		off_t chunk_offset = 0;
		off_t last_chunk_offset = 0;
		unsigned int buf_offset = 0;
		int lh_last_idx;
		int synced_idx = 0;

		/* skip records not set in bitmap */
		while (index <= last_index &&
		       llog_is_index_skipable(index, llh, cd))
			++index;

		/* There are no indices prior the last_index */
		if (index > last_index)
			break;

		CDEBUG(D_OTHER, "index: %d last_index %d\n", index,
		       last_index);

repeat:
		/* get the buf with our target record; avoid old garbage */
		memset(buf, 0, chunk_size);
		/* the record index for outdated chunk data */
		/* it is safe to process buffer until saved lgh_last_idx */
		lh_last_idx = LLOG_HDR_TAIL(llh)->lrt_index;
		rc = llog_next_block(env, loghandle, &saved_index,
				     index, &cur_offset, buf, chunk_size);
		if (repeated && rc)
			CDEBUG(D_OTHER, "cur_offset %llu, chunk_offset %llu,"
			       " buf_offset %u, rc = %d\n", cur_offset,
			       (__u64)chunk_offset, buf_offset, rc);
		if (rc == -ESTALE)
			GOTO(out, rc = 0);
		/* we`ve tried to reread the chunk, but there is no
		 * new records */
		if (repeated && (chunk_offset + buf_offset) == cur_offset &&
		    (rc == -EBADR || rc == -EIO))
			GOTO(out, rc = 0);
		/* EOF while trying to skip to the next chunk */
		if (!index && rc == -EBADR)
			GOTO(out, rc = 0);
		if (rc != 0)
			GOTO(out, rc);

		/* NB: after llog_next_block() call the cur_offset is the
		 * offset of the next block after read one.
		 * The absolute offset of the current chunk is calculated
		 * from cur_offset value and stored in chunk_offset variable.
		 */
		last_chunk_offset = chunk_offset;
		if ((cur_offset & (chunk_size - 1)) != 0)
			chunk_offset = cur_offset & ~(chunk_size - 1);
		else
			chunk_offset = cur_offset - chunk_size;

		/* When reread a chunk with zeores at the end, it could
		 * happened that index was found at next chunk. Start
		 * processing from a beginning.
		 */
		if (last_chunk_offset != chunk_offset)
			buf_offset = 0;

		/* 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 + buf_offset);
		     (char *)rec <= buf + chunk_size - LLOG_MIN_REC_SIZE;
		     rec = llog_rec_hdr_next(rec)) {

			if (LLOG_REC_HDR_NEEDS_SWABBING(rec))
				lustre_swab_llog_rec(rec);

			CDEBUG(D_OTHER, "processing rec 0x%px type=%#x idx=%d\n",
			       rec, rec->lrh_type, rec->lrh_index);

			/* start with first rec if block was skipped */
			if (!index) {
				CDEBUG(D_OTHER,
				       "%s: skipping to the index %u\n",
				       loghandle2name(loghandle),
				       rec->lrh_index);
				index = rec->lrh_index;
			}

			if (index == (synced_idx + 1) &&
			    synced_idx == LLOG_HDR_TAIL(llh)->lrt_index)
				GOTO(out, rc = 0);

			if (CFS_FAIL_PRECHECK(OBD_FAIL_LLOG_PROCESS_TIMEOUT) &&
				cfs_fail_val == (unsigned int)
					(loghandle->lgh_id.lgl_oi.oi.oi_id &
					 0xFFFFFFFF)) {
				CFS_RACE(OBD_FAIL_LLOG_PROCESS_TIMEOUT);
			}

			/* the bitmap could be changed during processing
			 * records from the chunk. For wrapped catalog
			 * it means we can read deleted record and try to
			 * process it. Check this case and reread the chunk.
			 * It is safe to process to lh_last_idx, including
			 * lh_last_idx if it was synced. We can not do <=
			 * comparison, cause for wrapped catalog lgh_last_idx
			 * could be less than index. So we detect last index
			 * for processing as index == lh_last_idx+1. But when
			 * catalog is wrapped and full lgh_last_idx=llh_cat_idx,
			 * the first processing index is llh_cat_idx+1.The
			 * exception is !(lgh_last_idx == llh_cat_idx &&
			 * index == llh_cat_idx + 1), and after simplification
			 * it turns to
			 * lh_last_idx != LLOG_HDR_TAIL(llh)->lrt_index
			 * This exception is working for catalog only.
			 * The last check is for the partial chunk boundary,
			 * if it is reached then try to re-read for possible
			 * new records once.
			 */
			if ((index == lh_last_idx && synced_idx != index) ||
			    (index == (lh_last_idx + 1) &&
			     lh_last_idx != LLOG_HDR_TAIL(llh)->lrt_index) ||
			    (((char *)rec - buf >= cur_offset - chunk_offset) &&
			    !repeated)) {
				/* save offset inside buffer for the re-read */
				buf_offset = (char *)rec - (char *)buf;
				cur_offset = chunk_offset;
				repeated = true;
				/* We need to be sure lgh_last_idx
				 * record was saved to disk
				 */
				down_read(&loghandle->lgh_last_sem);
				synced_idx = LLOG_HDR_TAIL(llh)->lrt_index;
				up_read(&loghandle->lgh_last_sem);
				CDEBUG(D_OTHER, "synced_idx: %d\n", synced_idx);
				goto repeat;
			}
			repeated = false;

			rc = llog_verify_record(loghandle, rec);
			if (rc) {
				int gap_size;

				CDEBUG(D_OTHER, "invalid record at index %d\n",
				       index);
				/*
				 * for fixed-sized llogs we can skip one record
				 * by using llh_size from llog header.
				 */
				rc = 0;
				if (llh->llh_flags & LLOG_F_IS_FIXSIZE) {
					rec->lrh_len = llh->llh_size;
					goto next_rec;
				}
				/*
				 * for zero gap we can find a next record.
				 * Otherwise skip the next llog chunk.
				 */
				gap_size = llog_skip_gap(rec, buf + chunk_size -
							 LLOG_MIN_REC_SIZE);
				if (gap_size > 0) {
					rec->lrh_len = gap_size;
					goto next_rec;
				}
				/* make sure that is always next block */
				cur_offset = chunk_offset + chunk_size;
				/* no goal to find, just next block to read */
				index = 0;
				break;
			}

			if (rec->lrh_index < index) {
				CDEBUG(D_OTHER, "skipping lrh_index %d\n",
				       rec->lrh_index);
				continue;
			}

			if (rec->lrh_index > index) {
				/* the record itself looks good, but we met a
				 * gap which can be result of old bugs, just
				 * keep going */
				LLOG_ERROR_REC(loghandle, rec,
					       "gap in index, expected %u",
					       index);
				index = rec->lrh_index;
			}

			CDEBUG(D_OTHER,
			       "lrh_index: %d lrh_len: %d (%d remains)\n",
			       rec->lrh_index, rec->lrh_len,
			       (int)(buf + chunk_size - (char *)rec));

			/* lgh_cur_offset is used only at llog_test_3 and
			 * changelog
			 */
			if (unlikely(loghandle->lgh_ctxt->loc_idx ==
				     LLOG_TEST_ORIG_CTXT))
				loghandle->lgh_cur_offset = (char *)rec -
						(char *)buf + chunk_offset;

			/* if needed, process the callback on this record */
			if (!llog_is_index_skipable(index, llh, cd)) {
				struct llog_cookie *lgc;
				__u64	tmp_off;
				int	tmp_idx;

				CDEBUG((llh->llh_flags & LLOG_F_IS_CAT ?
					D_HA : D_OTHER),
				       "index: %d, lh_last_idx: %d "
				       "synced_idx: %d lgh_last_idx: %d\n",
				       index, lh_last_idx, synced_idx,
				       loghandle->lgh_last_idx);

				if (lti != NULL) {
					lgc = &lti->lgi_cookie;
					/* store lu_env for recursive calls */
					tmp_off = lgc->lgc_offset;
					tmp_idx = lgc->lgc_index;

					lgc->lgc_offset = (char *)rec -
						(char *)buf + chunk_offset;
					lgc->lgc_index = rec->lrh_index;
				}
				/* using lu_env for passing record offset to
				 * llog_write through various callbacks */
				rc = lpi->lpi_cb(env, loghandle, rec,
						 lpi->lpi_cbdata);
				last_called_index = index;

				if (lti != NULL) {
					lgc->lgc_offset = tmp_off;
					lgc->lgc_index = tmp_idx;
				}

				if (rc == LLOG_PROC_BREAK ||
				    rc == LLOG_SKIP_PLAIN) {
					GOTO(out, rc);
				} else if (rc == LLOG_DEL_RECORD) {
					rc = llog_cancel_rec(env,
							     loghandle,
							     rec->lrh_index);
					/* Allow parallel cancelling, ENOENT
					 * means record was canceled at another
					 * processing thread or callback
					 */
					if (rc == -ENOENT)
						rc = 0;
				}
				if (rc)
					GOTO(out, rc);
				/* some stupid callbacks directly cancel records
				 * and delete llog. Check it and stop
				 * processing. */
				if (loghandle->lgh_hdr == NULL ||
				    loghandle->lgh_hdr->llh_count == 1)
					GOTO(out, rc = 0);
			}
next_rec:
			/* exit if the last index is reached */
			if (index >= last_index)
				GOTO(out, rc = 0);
			++index;
		}
	}

out:
	CDEBUG(D_HA, "stop processing %s "DFID" index %d count %d\n",
	       ((llh->llh_flags & LLOG_F_IS_CAT) ? "catalog" : "plain"),
	       PLOGID(&loghandle->lgh_id), index, llh->llh_count);

	if (cd != NULL)
		cd->lpcd_last_idx = last_called_index;

	if ((rc == -EIO || rc == -EINVAL) && loghandle->lgh_obj != NULL) {
		if (dt_object_remote(loghandle->lgh_obj)) {
			/* If it is remote object, then -EIO might means
			 * disconnection or eviction, let's return -EAGAIN,
			 * so for update recovery log processing, it will
			 * retry until the umount or abort recovery, see
			 * lod_sub_recovery_thread() */
			CERROR("%s retry remote llog process\n",
			       loghandle2name(loghandle));
			rc = -EAGAIN;
		} else {
			/* something bad happened to the processing of a local
			 * llog file, probably I/O error or the log got
			 * corrupted to be able to finally release the log we
			 * discard any remaining bits in the header */
			CERROR("%s: local llog is corrupted "DFID" %s index %d count %d\n",
			       loghandle2name(loghandle),
			       PLOGID(&loghandle->lgh_id),
			       ((llh->llh_flags & LLOG_F_IS_CAT) ? "catalog" :
			       "plain"), index, llh->llh_count);

			while (index <= last_index) {
				if (test_bit_le(index,
						  LLOG_HDR_BITMAP(llh)) != 0)
					llog_cancel_rec(env, loghandle,
							index);
				index++;
			}
			rc = 0;
		}
	}

	OBD_FREE_LARGE(buf, chunk_size);
out_env:
	if (env == &_env) {
		lu_env_remove(&_env);
out_fini:
		lu_env_fini(&_env);
	}

	lpi->lpi_rc = rc;
	return 0;
}

static int llog_process_thread_daemonize(void *arg)
{
	struct llog_process_info	*lpi = arg;
	int				 rc;
	struct nsproxy			*new_ns, *curr_ns = current->nsproxy;

	task_lock(lpi->lpi_reftask);
	new_ns = lpi->lpi_reftask->nsproxy;
	if (curr_ns != new_ns) {
		get_nsproxy(new_ns);

		current->nsproxy = new_ns;
		/* XXX: we should call put_nsproxy() instead of
		 * atomic_dec(&ns->count) directly. But put_nsproxy() cannot be
		 * used outside of the kernel itself, because it calls
		 * free_nsproxy() which is not exported by the kernel
		 * (defined in kernel/nsproxy.c) */
		if (curr_ns)
			nsproxy_dec(curr_ns);
	}
	task_unlock(lpi->lpi_reftask);

	unshare_fs_struct();

	rc = llog_process_thread(arg);

	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;
	struct llog_process_data *d = data;
	struct llog_process_cat_data *cd = catdata;
	__u32 flags = loghandle->lgh_hdr->llh_flags;
	int rc;

	ENTRY;

	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;

	CDEBUG(D_OTHER, "Processing "DFID" flags 0x%03x startcat %d startidx %d first_idx %d last_idx %d read_mode %d\n",
	       PLOGID(&loghandle->lgh_id), flags,
	       (flags & LLOG_F_IS_CAT) && d ? d->lpd_startcat : -1,
	       (flags & LLOG_F_IS_CAT) && d ? d->lpd_startidx : -1,
	       cd ? cd->lpcd_first_idx : -1, cd ? cd->lpcd_last_idx : -1,
	       cd ? cd->lpcd_read_mode : -1);
	if (fork) {
		struct task_struct *task;

		/* The new thread can't use parent env,
		 * init the new one in llog_process_thread_daemonize. */
		init_completion(&lpi->lpi_completion);
		/* take reference to current, so that
		 * llog_process_thread_daemonize() can use it to switch to
		 * namespace associated with current  */
		lpi->lpi_reftask = current;
		task = kthread_run(llog_process_thread_daemonize, lpi,
				   "llog_process_thread");
		if (IS_ERR(task)) {
			rc = PTR_ERR(task);
			CERROR("%s: cannot start thread: rc = %d\n",
			       loghandle2name(loghandle), rc);
			GOTO(out_lpi, rc);
		}
		wait_for_completion(&lpi->lpi_completion);
	} else {
		llog_process_thread(lpi);
	}
	rc = lpi->lpi_rc;

out_lpi:
	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)
{
	int rc;
	rc = llog_process_or_fork(env, loghandle, cb, data, catdata, true);
	return rc == LLOG_DEL_PLAIN ? 0 : rc;
}
EXPORT_SYMBOL(llog_process);

static inline const struct cred *llog_raise_resource(void)
{
	struct cred *cred = NULL;

	if (cap_raised(current_cap(), CAP_SYS_RESOURCE))
		return cred;

	cred = prepare_creds();
	if (!cred)
		return cred;

	cap_raise(cred->cap_effective, CAP_SYS_RESOURCE);
	return override_creds(cred);
}

static inline void llog_restore_resource(const struct cred *old_cred)
{
	if (old_cred)
		revert_creds(old_cred);
}

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;
	__u32	chunk_size = llh->llh_hdr.lrh_len;
        ENTRY;

	OBD_ALLOC_LARGE(buf, chunk_size);
	if (buf == NULL)
		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_max_idx(llh);

	while (rc == 0) {
		struct llog_rec_hdr *rec;
		struct llog_rec_tail *tail;

		/* skip records not set in bitmap */
		while (index >= first_index &&
		       llog_is_index_skipable(index, llh, cd))
			--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, chunk_size);
		rc = llog_prev_block(env, loghandle, index, buf, chunk_size);
		if (rc)
			GOTO(out, rc);

		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)
				GOTO(out, rc = 0); /* no more records */

			/* if needed, process the callback on this record */
			if (!llog_is_index_skipable(index, llh, cd)) {
				rec = (void *)tail - tail->lrt_len +
				      sizeof(*tail);

				rc = cb(env, loghandle, rec, data);
				if (rc == LLOG_PROC_BREAK ||
				    rc == LLOG_SKIP_PLAIN) {
					GOTO(out, rc);
				} else if (rc == LLOG_DEL_RECORD) {
					rc = llog_cancel_rec(env, loghandle,
							     tail->lrt_index);
				}
                                if (rc)
                                        GOTO(out, rc);
                        }

                        /* previous record, still in buffer? */
                        --index;
                        if (index < first_index)
                                GOTO(out, rc = 0);
			tail = (void *)tail - tail->lrt_len;
                }
        }

out:
	if (buf != NULL)
		OBD_FREE_LARGE(buf, chunk_size);
        RETURN(rc);
}
EXPORT_SYMBOL(llog_reverse_process);

/**
 * llog_exist() - new llog API
 * @loghandle: llog handle of the current llog
 *
 * 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
 *
 * Return:
 * * %0 on success
 * * %negative on error
 */
int llog_exist(struct llog_handle *loghandle)
{
	const 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)
{
	const struct cred *old_cred;
	const struct llog_operations *lop;
	int rc;

	ENTRY;

	rc = llog_handle2ops(loghandle, &lop);
	if (rc)
		RETURN(rc);
	if (lop->lop_declare_create == NULL)
		RETURN(-EOPNOTSUPP);

	old_cred = llog_raise_resource();
	rc = lop->lop_declare_create(env, loghandle, th);
	llog_restore_resource(old_cred);
	RETURN(rc);
}

int llog_create(const struct lu_env *env, struct llog_handle *handle,
		struct thandle *th)
{
	const struct cred *old_cred;
	const struct llog_operations *lop;
	int rc;

	ENTRY;

	rc = llog_handle2ops(handle, &lop);
	if (rc)
		RETURN(rc);
	if (lop->lop_create == NULL)
		RETURN(-EOPNOTSUPP);

	old_cred = llog_raise_resource();
	rc = lop->lop_create(env, handle, th);
	llog_restore_resource(old_cred);
	RETURN(rc);
}

int llog_declare_write_rec(const struct lu_env *env,
			   struct llog_handle *handle,
			   struct llog_rec_hdr *rec, int idx,
			   struct thandle *th)
{
	const struct cred *old_cred;
	const struct llog_operations *lop;
	int rc;

	ENTRY;

	rc = llog_handle2ops(handle, &lop);
	if (rc)
		RETURN(rc);
	LASSERT(lop);
	if (lop->lop_declare_write_rec == NULL)
		RETURN(-EOPNOTSUPP);

	old_cred = llog_raise_resource();
	rc = lop->lop_declare_write_rec(env, handle, rec, idx, th);
	llog_restore_resource(old_cred);
	RETURN(rc);
}

int llog_write_rec(const struct lu_env *env, struct llog_handle *handle,
		   struct llog_rec_hdr *rec, struct llog_cookie *logcookies,
		   int idx, struct thandle *th)
{
	const struct cred *old_cred;
	const struct llog_operations *lop;
	int rc, buflen;

	ENTRY;

	/* API sanity checks */
	if (handle == NULL) {
		CERROR("loghandle is missed\n");
		RETURN(-EPROTO);
	} else if (handle->lgh_obj == NULL) {
		CERROR("loghandle %p with NULL object\n",
			handle);
		RETURN(-EPROTO);
	} else if (th == NULL) {
		CERROR("%s: missed transaction handle\n",
		       loghandle2name(handle));
		RETURN(-EPROTO);
	} else if (handle->lgh_hdr == NULL) {
		CERROR("%s: loghandle %p with no header\n",
		       loghandle2name(handle), handle);
		RETURN(-EPROTO);
	}

	rc = llog_handle2ops(handle, &lop);
	if (rc)
		RETURN(rc);

	if (lop->lop_write_rec == NULL)
		RETURN(-EOPNOTSUPP);

	buflen = rec->lrh_len;
	LASSERT(round_up(buflen, 8) == buflen);

	old_cred = llog_raise_resource();
	rc = lop->lop_write_rec(env, handle, rec, logcookies, idx, th);
	llog_restore_resource(old_cred);
	RETURN(rc);
}

int llog_add(const struct lu_env *env, struct llog_handle *lgh,
	     struct llog_rec_hdr *rec, struct llog_cookie *logcookies,
	     struct thandle *th)
{
	const struct cred *old_cred;
	int rc;

	ENTRY;

	if (lgh->lgh_logops->lop_add == NULL)
		RETURN(-EOPNOTSUPP);

	old_cred = llog_raise_resource();
	rc = lgh->lgh_logops->lop_add(env, lgh, rec, logcookies, th);
	llog_restore_resource(old_cred);
	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)
{
	const struct cred *old_cred;
	int rc;

	ENTRY;

	if (lgh->lgh_logops->lop_declare_add == NULL)
		RETURN(-EOPNOTSUPP);

	old_cred = llog_raise_resource();
	rc = lgh->lgh_logops->lop_declare_add(env, lgh, rec, th);
	llog_restore_resource(old_cred);
	RETURN(rc);
}
EXPORT_SYMBOL(llog_declare_add);

/**
 * llog_open_create() - open/create llog
 * @env: current lustre environment
 * @ctxt: llog context
 * @res: llog handle of the newly created/open llog [out]
 * @logid: llog unique id
 * @name: llog name
 *
 * Helper function to open llog or create it if doesn't exist.
 * It hides all transaction handling from caller.
 *
 * Return:
 * * %0 on success
 * * %negative on error
 */
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);

	if (unlikely(unlikely(d->dd_rdonly)))
		GOTO(out, rc = -EROFS);

	th = dt_trans_create(env, d);
	if (IS_ERR(th))
		GOTO(out, rc = PTR_ERR(th));

	/* Create update llog object synchronously, which
	 * happens during inialization process see
	 * lod_sub_prep_llog(), to make sure the update
	 * llog object is created before corss-MDT writing
	 * updates into the llog object */
	if (ctxt->loc_flags & LLOG_CTXT_FLAG_NORMAL_FID)
		th->th_sync = 1;

	th->th_wait_submit = 1;
	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);

/**
 * llog_erase() - Helper function to delete existent llog.
 * @env: current lustre environment
 * @ctxt: llog context
 * @logid: llog unique id
 * @name: llog name
 *
 * Return:
 * * %0 on success
 * * %negative on error
 */
int llog_erase(const struct lu_env *env, struct llog_ctxt *ctxt,
	       struct llog_logid *logid, char *name)
{
	struct llog_handle *handle;
	int rc;

	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_destroy(env, handle);
	llog_close(env, handle);

	RETURN(rc);
}
EXPORT_SYMBOL(llog_erase);

/*
 * Get record cookie, with record file offset, should be called only by
 * llog_process_thread() callbacks.
 */
void llog_get_cookie(const struct lu_env *env, struct llog_cookie *out)
{
	struct llog_thread_info *lti = llog_info(env);

	LASSERT(out && env && lti);

	memcpy(out, &lti->lgi_cookie, sizeof(lti->lgi_cookie));

	return;
}
EXPORT_SYMBOL(llog_get_cookie);

/**
 * llog_write_cookie() - write record in llog with a custom cookie.
 * @env: execution environment
 * @loghandle: llog handle of the current llog
 * @rec: llog record header. This is a real header of
 *	the full llog record to write. This is
 *	the beginning of buffer to write, the length
 *	of buffer is stored in @rec::lrh_len
 * @cookie: pointer to the cookie to return back if needed.
 *	It is used for further cancel of this llog
 *	record. [in, out]
 * @idx: index of the llog record. If @idx == -1 then
 *	this is append case, otherwise @idx is
 *	the index of record to modify
 * Helper function for write record in llog with a custom cookie.
 * It hides all transaction handling from caller.
 * Valid only with local llog.
 *
 * Return:
 * * %0 on successful write && @cookie == NULL
 * * %1 on successful write && @cookie != NULL
 * * %negative error if write failed
 */
int llog_write_cookie(const struct lu_env *env, struct llog_handle *loghandle,
		      struct llog_rec_hdr *rec, struct llog_cookie *cookie,
		      int idx)
{
	struct dt_device	*dt;
	struct thandle		*th;
	struct llog_thread_info *lgi = llog_info(env);
	bool need_cookie;
	bool update_attr;
	unsigned long timestamp;
	int rc;

	ENTRY;

	LASSERT(loghandle);
	LASSERT(loghandle->lgh_ctxt);
	LASSERT(loghandle->lgh_obj != NULL);

	dt = lu2dt_dev(loghandle->lgh_obj->do_lu.lo_dev);

	if (unlikely(unlikely(dt->dd_rdonly)))
		RETURN(-EROFS);

	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);

	/*
	 * update mtime given 1) append mode, no overhead since inode
	 * size/block needs to be written anyway; 2) update for catalog
	 * since this doesn't happen very often
	 */
	timestamp = ktime_get_real_seconds();

	update_attr = (timestamp != loghandle->lgh_timestamp) &&
		       (idx == LLOG_NEXT_IDX ||
		       (loghandle->lgh_hdr &&
			loghandle->lgh_hdr->llh_flags & LLOG_F_IS_CAT));
	if (update_attr)
		dt_declare_attr_set(env, loghandle->lgh_obj, NULL, th);

	th->th_wait_submit = 1;
	rc = dt_trans_start_local(env, dt, th);
	if (rc)
		GOTO(out_trans, rc);

	need_cookie = !(idx == LLOG_HEADER_IDX || idx == LLOG_NEXT_IDX);

	down_write(&loghandle->lgh_lock);
	if (need_cookie && !cookie) {
		struct llog_thread_info *lti = llog_info(env);

		/* cookie comes from llog_process_thread */
		rc = llog_write_rec(env, loghandle, rec, &lti->lgi_cookie,
				    rec->lrh_index, th);
		/* upper layer didn`t pass cookie so change rc */
		rc = (rc == 1 ? 0 : rc);
	} else {
		rc = llog_write_rec(env, loghandle, rec, cookie, idx, th);
	}
	if (rc == 0 && update_attr) {
		loghandle->lgh_timestamp = timestamp;
		lgi->lgi_attr.la_valid = LA_MTIME;
		lgi->lgi_attr.la_mtime = timestamp;
		dt_attr_set(env, loghandle->lgh_obj, &lgi->lgi_attr, th);
	}

	up_write(&loghandle->lgh_lock);
out_trans:
	dt_trans_stop(env, dt, th);
	RETURN(rc);
}
EXPORT_SYMBOL(llog_write_cookie);

int llog_write(const struct lu_env *env, struct llog_handle *loghandle,
	       struct llog_rec_hdr *rec, int idx)
{
	return llog_write_cookie(env, loghandle, rec, NULL, idx);
}
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)
{
	const struct cred *old_cred;
	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;

	old_cred = llog_raise_resource();
	rc = ctxt->loc_logops->lop_open(env, *lgh, logid, name, open_param);
	llog_restore_resource(old_cred);
	if (rc) {
		CDEBUG(D_OTHER, "%s: Failed to open llog %s: rc %d\n",
		       ctxt->loc_obd->obd_name, name ? name : "", 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)
{
	return llog_handle_put(env, loghandle);
}
EXPORT_SYMBOL(llog_close);

/**
 * llog_is_empty() -  get the llog size in records
 * @env: execution environment
 * @ctxt: llog context
 * @name: llog name
 *
 * Helper function to get the llog size in records. It is used by MGS
 * mostly to check that config llog exists and contains data.
 *
 * Return:
 * * %true if there are records in llog besides a header
 * * %false on error or llog without records
 */
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:
	/* The header is record 1, the llog is still considered as empty
	 * if there is only header */
	return (rc <= 1);
}
EXPORT_SYMBOL(llog_is_empty);

/* this callback run in raw read mode (canceled record are processed) */
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;
	int idx = rec->lrh_index;
	int rc;

	ENTRY;

	if (CFS_FAIL_CHECK(OBD_FAIL_LLOG_BACKUP_ENOSPC))
		RETURN(-ENOSPC);

	/* Append all records */
	rc = llog_write(env, copy_llh, rec, LLOG_NEXT_IDX);

	/* Cancel the record if it is canceled on the source */
	if (!rc && !test_bit_le(idx, LLOG_HDR_BITMAP(llh->lgh_hdr)))
		rc = llog_cancel_rec(env, copy_llh, copy_llh->lgh_last_idx);

	RETURN(rc);
}

/* 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;
	struct llog_process_cat_data cd = {0};
	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,
			      &llh->lgh_hdr->llh_tgtuuid);
	if (rc)
		GOTO(out_backup, rc);

	/* Read canceled records to have an exact copy */
	cd.lpcd_read_mode = LLOG_READ_MODE_RAW;
	/* Copy log record by record */
	rc = llog_process_or_fork(env, llh, llog_copy_handler, (void *)bllh,
				  &cd, 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);

/* just count processed records */
static inline int llog_validate_record(const struct lu_env *env,
				       struct llog_handle *llh,
				       struct llog_rec_hdr *rec, void *data)
{
	int *recs = data;

	(*recs)++;
	return 0;
}

/* validate plain llog by reading all its records */
int llog_validate(const struct lu_env *env, struct llog_ctxt *ctxt, char *name)
{
	struct llog_handle *llh;
	struct llog_process_cat_data cd = { 0 };
	unsigned int recs;
	unsigned int processed = 1; /* one for header */
	int rc;

	ENTRY;

	rc = llog_open(env, ctxt, &llh, NULL, name, LLOG_OPEN_EXISTS);
	if (rc < 0)
		RETURN(rc);

	rc = llog_init_handle(env, llh, LLOG_F_IS_PLAIN, NULL);
	if (rc)
		GOTO(out_close, rc);

	recs = llog_get_size(llh);
	if (recs <= 1)
		GOTO(out_close, rc = -ENOENT);

	rc = llog_process_or_fork(env, llh, llog_validate_record, &processed,
				  &cd, false);
	if (rc) {
		CWARN("%s: can't validate log %s: rc = %d\n",
		      ctxt->loc_obd->obd_name, name, rc);
	} else if (recs != processed) {
		rc = -EINVAL;
		CWARN("%s: %s has %d recs but %d were processed: rc = %d\n",
		      ctxt->loc_obd->obd_name, name, recs, processed, rc);
	}
out_close:
	llog_close(env, llh);
	RETURN(rc);
}
EXPORT_SYMBOL(llog_validate);

/* Get size of llog */
__u64 llog_size(const struct lu_env *env, struct llog_handle *llh)
{
	int rc;
	struct lu_attr la;

	rc = llh->lgh_obj->do_ops->do_attr_get(env, llh->lgh_obj, &la);
	if (rc) {
		CERROR("%s: attr_get failed for "DFID": rc = %d\n",
		       loghandle2name(llh), PLOGID(&llh->lgh_id), rc);
		return 0;
	}

	return la.la_size;
}
EXPORT_SYMBOL(llog_size);

/* set llog ctime to current, and set LLOG_F_RM_ON_ERR|LLOG_F_MAX_AGE flag in
 * log header. It will be reclaimed when expired (UPDATE_LOG_MAX_AGE old).
 */
int llog_retain(const struct lu_env *env, struct llog_handle *log)
{
	struct dt_object *dto = log->lgh_obj;
	struct dt_device *dt = lu2dt_dev(log->lgh_obj->do_lu.lo_dev);
	struct lu_attr la = { 0 };
	struct thandle *th;
	int rc;

	la.la_ctime = ktime_get_real_seconds();
	la.la_valid = LA_CTIME;

	th = dt_trans_create(env, dt);
	if (IS_ERR(th))
		return PTR_ERR(th);

	th->th_wait_submit = 1;
	log->lgh_hdr->llh_flags |= LLOG_F_MAX_AGE | LLOG_F_RM_ON_ERR;
	rc = llog_declare_write_rec(env, log, &log->lgh_hdr->llh_hdr, -1, th);
	if (rc)
		goto out_trans;

	rc = dt_declare_attr_set(env, dto, &la, th);
	if (rc)
		goto out_trans;

	rc = dt_trans_start_local(env, dt, th);
	if (rc)
		goto out_trans;

	rc = llog_write_rec(env, log, &log->lgh_hdr->llh_hdr, NULL,
			    LLOG_HEADER_IDX, th);
	if (rc)
		goto out_trans;

	rc = dt_attr_set(env, dto, &la, th);
out_trans:
	dt_trans_stop(env, dt, th);

	CDEBUG(D_OTHER, "retain log "DFID" rc = %d\n",
	       PLOGID(&log->lgh_id), rc);
	return rc;
}
EXPORT_SYMBOL(llog_retain);
