/*
 * 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) 2007, 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/include/lustre_log.h
 *
 * Generic infrastructure for managing a collection of logs.
 * These logs are used for:
 *
 * - orphan recovery: OST adds record on create
 * - mtime/size consistency: the OST adds a record on first write
 * - open/unlinked objects: OST adds a record on destroy
 *
 * - mds unlink log: the MDS adds an entry upon delete
 *
 * - raid1 replication log between OST's
 * - MDS replication logs
 */

#ifndef _LUSTRE_LOG_H
#define _LUSTRE_LOG_H

/** \defgroup log log
 *
 * @{
 */

#if defined(__linux__)
#include <linux/lustre_log.h>
#elif defined(__APPLE__)
#include <darwin/lustre_log.h>
#elif defined(__WINNT__)
#include <winnt/lustre_log.h>
#else
#error Unsupported operating system.
#endif

#include <obd_class.h>
#include <obd_ost.h>
#include <lustre/lustre_idl.h>
#include <dt_object.h>

#define LOG_NAME_LIMIT(logname, name)                   \
        snprintf(logname, sizeof(logname), "LOGS/%s", name)
#define LLOG_EEMPTY 4711

enum llog_open_param {
	LLOG_OPEN_EXISTS	= 0x0000,
	LLOG_OPEN_NEW		= 0x0001,
};

struct plain_handle_data {
        cfs_list_t          phd_entry;
        struct llog_handle *phd_cat_handle;
        struct llog_cookie  phd_cookie; /* cookie of this log in its cat */
};

struct cat_handle_data {
        cfs_list_t              chd_head;
        struct llog_handle     *chd_current_log; /* currently open log */
	struct llog_handle	*chd_next_log; /* llog to be used next */
};

static inline void logid_to_fid(struct llog_logid *id, struct lu_fid *fid)
{
	/* For compatibility purposes we identify pre-OSD (~< 2.3.51 MDS)
	 * logid's by non-zero ogen (inode generation) and convert them
	 * into IGIF */
	if (id->lgl_ogen == 0) {
		fid->f_seq = id->lgl_oseq;
		fid->f_oid = id->lgl_oid;
		fid->f_ver = 0;
	} else {
		lu_igif_build(fid, id->lgl_oid, id->lgl_ogen);
	}
}

static inline void fid_to_logid(struct lu_fid *fid, struct llog_logid *id)
{
	id->lgl_oseq = fid->f_seq;
	id->lgl_oid = fid->f_oid;
	id->lgl_ogen = 0;
}

struct llog_handle;

/* llog.c  -  general API */
int llog_init_handle(const struct lu_env *env, struct llog_handle *handle,
		     int flags, struct obd_uuid *uuid);
int llog_process(const struct lu_env *env, struct llog_handle *loghandle,
		 llog_cb_t cb, void *data, void *catdata);
int llog_process_or_fork(const struct lu_env *env,
			 struct llog_handle *loghandle,
			 llog_cb_t cb, void *data, void *catdata, bool fork);
int llog_reverse_process(const struct lu_env *env,
			 struct llog_handle *loghandle, llog_cb_t cb,
			 void *data, void *catdata);
int llog_cancel_rec(const struct lu_env *env, struct llog_handle *loghandle,
		    int index);
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 llog_close(const struct lu_env *env, struct llog_handle *cathandle);
int llog_get_size(struct llog_handle *loghandle);

/* llog_process flags */
#define LLOG_FLAG_NODEAMON 0x0001

/* llog_cat.c - catalog api */
struct llog_process_data {
        /**
         * Any useful data needed while processing catalog. This is
         * passed later to process callback.
         */
        void                *lpd_data;
        /**
         * Catalog process callback function, called for each record
         * in catalog.
         */
        llog_cb_t            lpd_cb;
        /**
         * Start processing the catalog from startcat/startidx
         */
        int                  lpd_startcat;
        int                  lpd_startidx;
};

struct llog_process_cat_data {
        /**
         * Temporary stored first_idx while scanning log.
         */
        int                  lpcd_first_idx;
        /**
         * Temporary stored last_idx while scanning log.
         */
        int                  lpcd_last_idx;
};

struct llog_process_cat_args {
        /**
         * Llog context used in recovery thread on OST (recov_thread.c)
         */
        struct llog_ctxt    *lpca_ctxt;
        /**
         * Llog callback used in recovery thread on OST (recov_thread.c)
         */
        void                *lpca_cb;
        /**
         * Data pointer for llog callback.
         */
        void                *lpca_arg;
};

int llog_cat_close(const struct lu_env *env, struct llog_handle *cathandle);
int llog_cat_add_rec(const struct lu_env *env, struct llog_handle *cathandle,
		     struct llog_rec_hdr *rec, struct llog_cookie *reccookie,
		     void *buf, struct thandle *th);
int llog_cat_declare_add_rec(const struct lu_env *env,
			     struct llog_handle *cathandle,
			     struct llog_rec_hdr *rec, struct thandle *th);
int llog_cat_add(const struct lu_env *env, struct llog_handle *cathandle,
		 struct llog_rec_hdr *rec, struct llog_cookie *reccookie,
		 void *buf);
int llog_cat_cancel_records(const struct lu_env *env,
			    struct llog_handle *cathandle, int count,
			    struct llog_cookie *cookies);
int llog_cat_process_or_fork(const struct lu_env *env,
			     struct llog_handle *cat_llh, llog_cb_t cb,
			     void *data, int startcat, int startidx, bool fork);
int llog_cat_process(const struct lu_env *env, struct llog_handle *cat_llh,
		     llog_cb_t cb, void *data, int startcat, int startidx);
int llog_cat_process_thread(void *data);
int llog_cat_reverse_process(const struct lu_env *env,
			     struct llog_handle *cat_llh, llog_cb_t cb,
			     void *data);
int llog_cat_init_and_process(const struct lu_env *env,
			      struct llog_handle *llh);

/* llog_obd.c */
int llog_setup(const struct lu_env *env, struct obd_device *obd,
	       struct obd_llog_group *olg, int index,
	       struct obd_device *disk_obd, struct llog_operations *op);
int __llog_ctxt_put(const struct lu_env *env, struct llog_ctxt *ctxt);
int llog_cleanup(const struct lu_env *env, struct llog_ctxt *);
int llog_sync(struct llog_ctxt *ctxt, struct obd_export *exp, int flags);
int llog_obd_add(const struct lu_env *env, struct llog_ctxt *ctxt,
		 struct llog_rec_hdr *rec, struct lov_stripe_md *lsm,
		 struct llog_cookie *logcookies, int numcookies);
int llog_cancel(const struct lu_env *env, struct llog_ctxt *ctxt,
		struct lov_stripe_md *lsm, int count,
		struct llog_cookie *cookies, int flags);
int llog_obd_origin_add(const struct lu_env *env, struct llog_ctxt *ctxt,
			struct llog_rec_hdr *rec, struct lov_stripe_md *lsm,
			struct llog_cookie *logcookies, int numcookies);

int obd_llog_init(struct obd_device *obd, struct obd_llog_group *olg,
                  struct obd_device *disk_obd, int *idx);

int obd_llog_finish(struct obd_device *obd, int count);

/* llog_ioctl.c */
int llog_ioctl(const struct lu_env *env, struct llog_ctxt *ctxt, int cmd,
	       struct obd_ioctl_data *data);
int llog_catalog_list(struct obd_device *obd, int count,
                      struct obd_ioctl_data *data);

/* llog_net.c */
int llog_initiator_connect(struct llog_ctxt *ctxt);
int llog_receptor_accept(struct llog_ctxt *ctxt, struct obd_import *imp);
int llog_origin_connect(struct llog_ctxt *ctxt,
                        struct llog_logid *logid, struct llog_gen *gen,
                        struct obd_uuid *uuid);
int llog_handle_connect(struct ptlrpc_request *req);

/* recov_thread.c */
int llog_obd_repl_cancel(const struct lu_env *env, struct llog_ctxt *ctxt,
			 struct lov_stripe_md *lsm, int count,
			 struct llog_cookie *cookies, int flags);
int llog_obd_repl_sync(struct llog_ctxt *ctxt, struct obd_export *exp,
		       int flags);
int llog_obd_repl_connect(struct llog_ctxt *ctxt,
                          struct llog_logid *logid, struct llog_gen *gen,
                          struct obd_uuid *uuid);

struct llog_operations {
	int (*lop_destroy)(const struct lu_env *env,
			   struct llog_handle *handle);
	int (*lop_next_block)(const struct lu_env *env, struct llog_handle *h,
			      int *curr_idx, int next_idx, __u64 *offset,
			      void *buf, int len);
	int (*lop_prev_block)(const struct lu_env *env, struct llog_handle *h,
			      int prev_idx, void *buf, int len);
	int (*lop_read_header)(const struct lu_env *env,
			       struct llog_handle *handle);
	int (*lop_setup)(const struct lu_env *env, struct obd_device *obd,
			 struct obd_llog_group *olg, int ctxt_idx,
			 struct obd_device *disk_obd);
	int (*lop_sync)(struct llog_ctxt *ctxt, struct obd_export *exp,
			int flags);
	int (*lop_cleanup)(const struct lu_env *env, struct llog_ctxt *ctxt);
	int (*lop_cancel)(const struct lu_env *env, struct llog_ctxt *ctxt,
			  struct lov_stripe_md *lsm, int count,
			  struct llog_cookie *cookies, int flags);
	int (*lop_connect)(struct llog_ctxt *ctxt, struct llog_logid *logid,
			   struct llog_gen *gen, struct obd_uuid *uuid);
	/**
	 * Any llog file must be opened first using llog_open().  Llog can be
	 * opened by name, logid or without both, in last case the new logid
	 * will be generated.
	 */
	int (*lop_open)(const struct lu_env *env, struct llog_handle *lgh,
			struct llog_logid *logid, char *name,
			enum llog_open_param);
	/**
	 * Opened llog may not exist and this must be checked where needed using
	 * the llog_exist() call.
	 */
	int (*lop_exist)(struct llog_handle *lgh);
	/**
	 * Close llog file and calls llog_free_handle() implicitly.
	 * Any opened llog must be closed by llog_close() call.
	 */
	int (*lop_close)(const struct lu_env *env, struct llog_handle *handle);
	/**
	 * Create new llog file. The llog must be opened.
	 * Must be used only for local llog operations.
	 */
	int (*lop_declare_create)(const struct lu_env *env,
				  struct llog_handle *handle,
				  struct thandle *th);
	int (*lop_create)(const struct lu_env *env, struct llog_handle *handle,
			  struct thandle *th);
	/**
	 * write new record in llog. It appends records usually but can edit
	 * existing records too.
	 */
	int (*lop_declare_write_rec)(const struct lu_env *env,
				     struct llog_handle *lgh,
				     struct llog_rec_hdr *rec,
				     int idx, struct thandle *th);
	int (*lop_write_rec)(const struct lu_env *env,
			     struct llog_handle *loghandle,
			     struct llog_rec_hdr *rec,
			     struct llog_cookie *cookie, int cookiecount,
			     void *buf, int idx, struct thandle *th);
	/**
	 * Add new record in llog catalog. Does the same as llog_write_rec()
	 * but using llog catalog.
	 */
	int (*lop_declare_add)(const struct lu_env *env,
			       struct llog_handle *lgh,
			       struct llog_rec_hdr *rec, struct thandle *th);
	int (*lop_add)(const struct lu_env *env, struct llog_handle *lgh,
		       struct llog_rec_hdr *rec, struct llog_cookie *cookie,
		       void *buf, struct thandle *th);
	/* Old llog_add version, used in MDS-LOV-OSC now and will gone with
	 * LOD/OSP replacement */
	int (*lop_obd_add)(const struct lu_env *env, struct llog_ctxt *ctxt,
			   struct llog_rec_hdr *rec, struct lov_stripe_md *lsm,
			   struct llog_cookie *logcookies, int numcookies);
};

/* In-memory descriptor for a log object or log catalog */
struct llog_handle {
	struct rw_semaphore	 lgh_lock;
	spinlock_t		 lgh_hdr_lock; /* protect lgh_hdr data */
	struct llog_logid	 lgh_id; /* id of this log */
	struct llog_log_hdr	*lgh_hdr;
	struct file		*lgh_file;
	struct dt_object	*lgh_obj;
	int			 lgh_last_idx;
	int			 lgh_cur_idx; /* used during llog_process */
	__u64			 lgh_cur_offset; /* used during llog_process */
	struct llog_ctxt	*lgh_ctxt;
	union {
		struct plain_handle_data	 phd;
		struct cat_handle_data		 chd;
	} u;
	char			*lgh_name;
	void			*private_data;
	struct llog_operations	*lgh_logops;
};

/* llog_lvfs.c */
extern struct llog_operations llog_lvfs_ops;
int llog_get_cat_list(struct obd_device *disk_obd,
                      char *name, int idx, int count,
                      struct llog_catid *idarray);

int llog_put_cat_list(struct obd_device *disk_obd,
                      char *name, int idx, int count, struct llog_catid *idarray);

/* llog_osd.c */
extern struct llog_operations llog_osd_ops;
int llog_osd_get_cat_list(const struct lu_env *env, struct dt_device *d,
			  int idx, int count, struct llog_catid *idarray);
int llog_osd_put_cat_list(const struct lu_env *env, struct dt_device *d,
			  int idx, int count, struct llog_catid *idarray);

#define LLOG_CTXT_FLAG_UNINITIALIZED     0x00000001
#define LLOG_CTXT_FLAG_STOP		 0x00000002

struct llog_ctxt {
        int                      loc_idx; /* my index the obd array of ctxt's */
        struct llog_gen          loc_gen;
        struct obd_device       *loc_obd; /* points back to the containing obd*/
        struct obd_llog_group   *loc_olg; /* group containing that ctxt */
        struct obd_export       *loc_exp; /* parent "disk" export (e.g. MDS) */
        struct obd_import       *loc_imp; /* to use in RPC's: can be backward
                                             pointing import */
        struct llog_operations  *loc_logops;
        struct llog_handle      *loc_handle;
        struct llog_commit_master *loc_lcm;
        struct llog_canceld_ctxt *loc_llcd;
	struct mutex		 loc_mutex; /* protect loc_llcd and loc_imp */
        cfs_atomic_t             loc_refcount;
        void                    *llog_proc_cb;
        long                     loc_flags; /* flags, see above defines */
	struct dt_object	*loc_dir;
};

#define LCM_NAME_SIZE 64

struct llog_commit_master {
        /**
         * Thread control flags (start, stop, etc.)
         */
        long                       lcm_flags;
        /**
         * Number of llcds onthis lcm.
         */
        cfs_atomic_t               lcm_count;
        /**
         * The refcount for lcm
         */
         cfs_atomic_t              lcm_refcount;
        /**
         * Thread control structure. Used for control commit thread.
         */
        struct ptlrpcd_ctl         lcm_pc;
        /**
         * Lock protecting list of llcds.
         */
	spinlock_t		   lcm_lock;
        /**
         * Llcds in flight for debugging purposes.
         */
        cfs_list_t                 lcm_llcds;
        /**
         * Commit thread name buffer. Only used for thread start.
         */
        char                       lcm_name[LCM_NAME_SIZE];
};

static inline struct llog_commit_master
*lcm_get(struct llog_commit_master *lcm)
{
        cfs_atomic_inc(&lcm->lcm_refcount);
        return lcm;
}

static inline void
lcm_put(struct llog_commit_master *lcm)
{
        LASSERT_ATOMIC_POS(&lcm->lcm_refcount);
        if (cfs_atomic_dec_and_test(&lcm->lcm_refcount))
                OBD_FREE_PTR(lcm);
}

struct llog_canceld_ctxt {
        /**
         * Llog context this llcd is attached to. Used for accessing
         * ->loc_import and others in process of canceling cookies
         * gathered in this llcd.
         */
        struct llog_ctxt          *llcd_ctxt;
        /**
         * Cancel thread control stucture pointer. Used for accessing
         * it to see if should stop processing and other needs.
         */
        struct llog_commit_master *llcd_lcm;
        /**
         * Maximal llcd size. Used in calculations on how much of room
         * left in llcd to cookie comming cookies.
         */
        int                        llcd_size;
        /**
         * Link to lcm llcds list.
         */
        cfs_list_t                 llcd_list;
        /**
         * Current llcd size while gathering cookies. This should not be
         * more than ->llcd_size. Used for determining if we need to
         * send this llcd (if full) and allocate new one. This is also
         * used for copying new cookie at the end of buffer.
         */
        int                        llcd_cookiebytes;
        /**
         * Pointer to the start of cookies buffer.
         */
        struct llog_cookie         llcd_cookies[0];
};

/* ptlrpc/recov_thread.c */
extern struct llog_commit_master *llog_recov_thread_init(char *name);
extern void llog_recov_thread_fini(struct llog_commit_master *lcm,
                                   int force);
extern int llog_recov_thread_start(struct llog_commit_master *lcm);
extern void llog_recov_thread_stop(struct llog_commit_master *lcm,
                                    int force);

static inline void llog_gen_init(struct llog_ctxt *ctxt)
{
        struct obd_device *obd = ctxt->loc_exp->exp_obd;

        LASSERTF(obd->u.obt.obt_magic == OBT_MAGIC,
                 "%s: wrong obt magic %#x\n",
                 obd->obd_name, obd->u.obt.obt_magic);
        ctxt->loc_gen.mnt_cnt = obd->u.obt.obt_mount_count;
        ctxt->loc_gen.conn_cnt++;
}

static inline int llog_gen_lt(struct llog_gen a, struct llog_gen b)
{
        if (a.mnt_cnt < b.mnt_cnt)
                return 1;
        if (a.mnt_cnt > b.mnt_cnt)
                return 0;
        return(a.conn_cnt < b.conn_cnt ? 1 : 0);
}

#define LLOG_PROC_BREAK 0x0001
#define LLOG_DEL_RECORD 0x0002

static inline int llog_obd2ops(struct llog_ctxt *ctxt,
                               struct llog_operations **lop)
{
        if (ctxt == NULL)
                return -ENOTCONN;

        *lop = ctxt->loc_logops;
        if (*lop == NULL)
                return -EOPNOTSUPP;

        return 0;
}

static inline int llog_handle2ops(struct llog_handle *loghandle,
                                  struct llog_operations **lop)
{
	if (loghandle == NULL || loghandle->lgh_logops == NULL)
		return -EINVAL;

	*lop = loghandle->lgh_logops;
	return 0;
}

static inline int llog_data_len(int len)
{
        return cfs_size_round(len);
}

static inline struct llog_ctxt *llog_ctxt_get(struct llog_ctxt *ctxt)
{
        cfs_atomic_inc(&ctxt->loc_refcount);
        CDEBUG(D_INFO, "GETting ctxt %p : new refcount %d\n", ctxt,
               cfs_atomic_read(&ctxt->loc_refcount));
        return ctxt;
}

static inline void llog_ctxt_put(struct llog_ctxt *ctxt)
{
        if (ctxt == NULL)
                return;
        LASSERT_ATOMIC_GT_LT(&ctxt->loc_refcount, 0, LI_POISON);
        CDEBUG(D_INFO, "PUTting ctxt %p : new refcount %d\n", ctxt,
               cfs_atomic_read(&ctxt->loc_refcount) - 1);
	__llog_ctxt_put(NULL, ctxt);
}

static inline void llog_group_init(struct obd_llog_group *olg, int group)
{
	cfs_waitq_init(&olg->olg_waitq);
	spin_lock_init(&olg->olg_lock);
	mutex_init(&olg->olg_cat_processing);
	olg->olg_seq = group;
}

static inline void llog_group_set_export(struct obd_llog_group *olg,
                                         struct obd_export *exp)
{
	LASSERT(exp != NULL);

	spin_lock(&olg->olg_lock);
	if (olg->olg_exp != NULL && olg->olg_exp != exp)
		CWARN("%s: export for group %d is changed: 0x%p -> 0x%p\n",
		      exp->exp_obd->obd_name, olg->olg_seq,
		      olg->olg_exp, exp);
	olg->olg_exp = exp;
	spin_unlock(&olg->olg_lock);
}

static inline int llog_group_set_ctxt(struct obd_llog_group *olg,
                                      struct llog_ctxt *ctxt, int index)
{
	LASSERT(index >= 0 && index < LLOG_MAX_CTXTS);

	spin_lock(&olg->olg_lock);
	if (olg->olg_ctxts[index] != NULL) {
		spin_unlock(&olg->olg_lock);
		return -EEXIST;
	}
	olg->olg_ctxts[index] = ctxt;
	spin_unlock(&olg->olg_lock);
	return 0;
}

static inline struct llog_ctxt *llog_group_get_ctxt(struct obd_llog_group *olg,
                                                    int index)
{
	struct llog_ctxt *ctxt;

	LASSERT(index >= 0 && index < LLOG_MAX_CTXTS);

	spin_lock(&olg->olg_lock);
	if (olg->olg_ctxts[index] == NULL)
		ctxt = NULL;
	else
		ctxt = llog_ctxt_get(olg->olg_ctxts[index]);
	spin_unlock(&olg->olg_lock);
	return ctxt;
}

static inline void llog_group_clear_ctxt(struct obd_llog_group *olg, int index)
{
	LASSERT(index >= 0 && index < LLOG_MAX_CTXTS);
	spin_lock(&olg->olg_lock);
	olg->olg_ctxts[index] = NULL;
	spin_unlock(&olg->olg_lock);
}

static inline struct llog_ctxt *llog_get_context(struct obd_device *obd,
                                                 int index)
{
        return llog_group_get_ctxt(&obd->obd_olg, index);
}

static inline int llog_group_ctxt_null(struct obd_llog_group *olg, int index)
{
        return (olg->olg_ctxts[index] == NULL);
}

static inline int llog_ctxt_null(struct obd_device *obd, int index)
{
        return (llog_group_ctxt_null(&obd->obd_olg, index));
}

static inline int llog_destroy(const struct lu_env *env,
			       struct llog_handle *handle)
{
	struct llog_operations *lop;
	int rc;

	ENTRY;

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

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

static inline int llog_next_block(const struct lu_env *env,
				  struct llog_handle *loghandle, int *cur_idx,
				  int next_idx, __u64 *cur_offset, void *buf,
				  int len)
{
	struct llog_operations *lop;
	int rc;

	ENTRY;

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

	rc = lop->lop_next_block(env, loghandle, cur_idx, next_idx,
				 cur_offset, buf, len);
	RETURN(rc);
}

static inline int llog_prev_block(const struct lu_env *env,
				  struct llog_handle *loghandle,
				  int prev_idx, void *buf, int len)
{
	struct llog_operations *lop;
	int rc;

	ENTRY;

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

	rc = lop->lop_prev_block(env, loghandle, prev_idx, buf, len);
	RETURN(rc);
}

static inline int llog_connect(struct llog_ctxt *ctxt,
			       struct llog_logid *logid, struct llog_gen *gen,
			       struct obd_uuid *uuid)
{
	struct llog_operations	*lop;
	int			 rc;

	ENTRY;

	rc = llog_obd2ops(ctxt, &lop);
	if (rc)
		RETURN(rc);
	if (lop->lop_connect == NULL)
		RETURN(-EOPNOTSUPP);

	rc = lop->lop_connect(ctxt, logid, gen, uuid);
	RETURN(rc);
}

/* llog.c */
int llog_exist(struct llog_handle *loghandle);
int llog_declare_create(const struct lu_env *env,
			struct llog_handle *loghandle, struct thandle *th);
int llog_create(const struct lu_env *env, struct llog_handle *handle,
		struct thandle *th);
int llog_declare_write_rec(const struct lu_env *env,
			   struct llog_handle *handle,
			   struct llog_rec_hdr *rec, int idx,
			   struct thandle *th);
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);
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 llog_declare_add(const struct lu_env *env, struct llog_handle *lgh,
		     struct llog_rec_hdr *rec, struct thandle *th);
int lustre_process_log(struct super_block *sb, char *logname,
		       struct config_llog_instance *cfg);
int lustre_end_log(struct super_block *sb, char *logname,
		   struct config_llog_instance *cfg);
int llog_open_create(const struct lu_env *env, struct llog_ctxt *ctxt,
		     struct llog_handle **res, struct llog_logid *logid,
		     char *name);
int llog_erase(const struct lu_env *env, struct llog_ctxt *ctxt,
	       struct llog_logid *logid, char *name);
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);

/** @} log */

#endif