/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
 * vim:expandtab:shiftwidth=8:tabstop=8:
 *
 *  Copyright (C) 2001-2003 Cluster File Systems, Inc.
 *   Author: Andreas Dilger <adilger@clusterfs.com>
 *
 *   This file is part of Lustre, http://www.lustre.org.
 *
 *   Lustre is free software; you can redistribute it and/or
 *   modify it under the terms of version 2 of the GNU General Public
 *   License as published by the Free Software Foundation.
 *
 *   Lustre 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 for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with Lustre; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * 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
 */

#define DEBUG_SUBSYSTEM S_LOG

#ifndef EXPORT_SYMTAB
#define EXPORT_SYMTAB
#endif

#ifdef __KERNEL__
#include <linux/fs.h>
#else
#include <liblustre.h>
#endif

#include <linux/lustre_log.h>

/* Allocate a new log or catalog handle */
struct llog_handle *llog_alloc_handle(void)
{
        struct llog_handle *loghandle;
        ENTRY;

        OBD_ALLOC(loghandle, sizeof(*loghandle));
        if (loghandle == NULL)
                RETURN(ERR_PTR(-ENOMEM));

        init_rwsem(&loghandle->lgh_lock);

        RETURN(loghandle);
}
EXPORT_SYMBOL(llog_alloc_handle);

void llog_free_handle(struct llog_handle *loghandle)
{
        if (!loghandle)
                return;

        if (!loghandle->lgh_hdr)
                goto out;
        if (le32_to_cpu(loghandle->lgh_hdr->llh_flags) & LLOG_F_IS_PLAIN)
                list_del_init(&loghandle->u.phd.phd_entry);
        if (le32_to_cpu(loghandle->lgh_hdr->llh_flags) & LLOG_F_IS_CAT)
                LASSERT(list_empty(&loghandle->u.chd.chd_head));
        OBD_FREE(loghandle->lgh_hdr, LLOG_CHUNK_SIZE);

 out:
        OBD_FREE(loghandle, sizeof(*loghandle));
}
EXPORT_SYMBOL(llog_free_handle);

/* returns negative on error; 0 if success; 1 if success & log destroyed */
int llog_cancel_rec(struct llog_handle *loghandle, int index)
{
        struct llog_log_hdr *llh = loghandle->lgh_hdr;
        int rc = 0;
        ENTRY;

        CDEBUG(D_HA, "canceling %d in log "LPX64"\n",
               index, loghandle->lgh_id.lgl_oid);

        if (index == 0) {
                CERROR("cannot cancel index 0 (which is header)\n");
                RETURN(-EINVAL);
        }

        if (!ext2_clear_bit(index, llh->llh_bitmap)) {
                CERROR("catalog index %u already clear?\n", index);
                RETURN(-EINVAL);
        }

        llh->llh_count = cpu_to_le32(le32_to_cpu(llh->llh_count) - 1);

        if ((le32_to_cpu(llh->llh_flags) & LLOG_F_ZAP_WHEN_EMPTY) &&
            (le32_to_cpu(llh->llh_count) == 1) &&
            (loghandle->lgh_last_idx == (LLOG_BITMAP_BYTES * 8) - 1)) {
                rc = llog_destroy(loghandle);
                if (rc) {
                        CERROR("failure destroying log after last cancel: %d\n",
                               rc);
                        ext2_set_bit(index, llh->llh_bitmap);
                        llh->llh_count++;
                } else {
                        rc = 1;
                }
                RETURN(rc);
        }

        rc = llog_write_rec(loghandle, &llh->llh_hdr, NULL, 0, NULL, 0);
        if (rc) {
                CERROR("failure re-writing header %d\n", rc);
                ext2_set_bit(index, llh->llh_bitmap);
                llh->llh_count++;
        }
        RETURN(rc);
}
EXPORT_SYMBOL(llog_cancel_rec);

int llog_init_handle(struct llog_handle *handle, int flags,
                     struct obd_uuid *uuid)
{
        int rc;
        struct llog_log_hdr *llh;
        ENTRY;
        LASSERT(handle->lgh_hdr == NULL);

        OBD_ALLOC(llh, sizeof(*llh));
        if (llh == NULL)
                RETURN(-ENOMEM);
        handle->lgh_hdr = llh;
        /* first assign flags to use llog_client_ops */
        llh->llh_flags = cpu_to_le32(flags);
        rc = llog_read_header(handle);
        if (rc == 0) {
                flags = le32_to_cpu(llh->llh_flags);
                if (uuid)
                        LASSERT(obd_uuid_equals(uuid, &llh->llh_tgtuuid));
                GOTO(out, rc);
        } else if (rc != LLOG_EEMPTY || !flags) {
                /* set a pesudo flag for initialization */
                flags = LLOG_F_IS_CAT;
                GOTO(out, rc);
        }
        rc = 0;

        handle->lgh_last_idx = 0; /* header is record with index 0 */
        llh->llh_count = cpu_to_le32(1);         /* for the header record */
        llh->llh_hdr.lrh_type = cpu_to_le32(LLOG_HDR_MAGIC);
        llh->llh_hdr.lrh_len = llh->llh_tail.lrt_len =
                cpu_to_le32(LLOG_CHUNK_SIZE);
        llh->llh_hdr.lrh_index = llh->llh_tail.lrt_index = 0;
        llh->llh_timestamp = cpu_to_le64(LTIME_S(CURRENT_TIME));
        if (uuid)
                memcpy(&llh->llh_tgtuuid, uuid, sizeof(llh->llh_tgtuuid));
        llh->llh_bitmap_offset = cpu_to_le32(offsetof(typeof(*llh),llh_bitmap));
        ext2_set_bit(0, llh->llh_bitmap);

out:
        if (flags & LLOG_F_IS_CAT) {
                INIT_LIST_HEAD(&handle->u.chd.chd_head);
                llh->llh_size = cpu_to_le32(sizeof(struct llog_logid_rec));
        }
        else if (flags & LLOG_F_IS_PLAIN)
                INIT_LIST_HEAD(&handle->u.phd.phd_entry);
        else
                LBUG();

        if (rc) {
                OBD_FREE(llh, sizeof(*llh));
                handle->lgh_hdr = NULL;
        }
        RETURN(rc);
}
EXPORT_SYMBOL(llog_init_handle);

int llog_close(struct llog_handle *loghandle)
{
        struct llog_operations *lop;
        int rc;
        ENTRY;

        rc = llog_handle2ops(loghandle, &lop);
        if (rc)
                GOTO(out, rc);
        if (lop->lop_close == NULL)
                GOTO(out, rc = -EOPNOTSUPP);
        rc = lop->lop_close(loghandle);
 out:
        llog_free_handle(loghandle);
        RETURN(rc);
}
EXPORT_SYMBOL(llog_close);

int llog_process(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;
        __u64 cur_offset = LLOG_CHUNK_SIZE;
        int rc = 0, index = 1, last_index, idx;
        int saved_index = 0;
        ENTRY;

        OBD_ALLOC(buf, LLOG_CHUNK_SIZE);
        if (!buf)
                RETURN(-ENOMEM);

        if (cd != NULL)
                index = cd->first_idx + 1;
        if (cd != NULL && cd->last_idx)
                last_index = cd->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;

                /* get the buf with our target record; avoid old garbage */
                memset(buf, 0, LLOG_CHUNK_SIZE);
                rc = llog_next_block(loghandle, &saved_index, index,
                                     &cur_offset, buf, LLOG_CHUNK_SIZE);
                if (rc)
                        GOTO(out, rc);

                rec = buf;
                idx = le32_to_cpu(rec->lrh_index);
                if (idx < index)
                        CDEBUG(D_HA, "index %u : idx %u\n", index, idx);
                while (idx < index) {
                        rec = ((void *)rec + le32_to_cpu(rec->lrh_len));
                        idx ++;
                }

                /* process records in buffer, starting where we found one */
                while ((void *)rec < buf + LLOG_CHUNK_SIZE) {
                        if (rec->lrh_index == 0)
                                GOTO(out, rc = 0); /* no more records */

                        /* if set, process the callback on this record */
                        if (ext2_test_bit(index, llh->llh_bitmap)) {
                                rc = cb(loghandle, rec, data);
                                if (rc == LLOG_PROC_BREAK) {
                                        CDEBUG(D_HA, "recovery from log: "LPX64":%x"
                                              " stopped\n",
                                              loghandle->lgh_id.lgl_oid,
                                              loghandle->lgh_id.lgl_ogen);
                                        GOTO(out, rc);
                                } else if (rc == LLOG_DEL_RECORD) {
                                        llog_cancel_rec(loghandle, rec->lrh_index);
                                        rc = 0;
                                } 
                                if (rc)
                                        GOTO(out, rc);
                        }
                        /* next record, still in buffer? */
                        ++index;
                        if (index > last_index)
                                GOTO(out, rc = 0);
                        rec = ((void *)rec + le32_to_cpu(rec->lrh_len));
                }
        }

 out:
        if (buf)
                OBD_FREE(buf, LLOG_CHUNK_SIZE);
        RETURN(rc);
}
EXPORT_SYMBOL(llog_process);

int llog_reverse_process(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;
        struct llog_rec_tail *tail;
        ENTRY;

        OBD_ALLOC(buf, LLOG_CHUNK_SIZE);
        if (!buf)
                RETURN(-ENOMEM);

        if (cd != NULL)
                first_index = cd->first_idx + 1;
        if (cd != NULL && cd->last_idx)
                index = cd->last_idx;
        else
                index = LLOG_BITMAP_BYTES * 8 - 1;

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

                /* 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(loghandle, index, buf, LLOG_CHUNK_SIZE);
                if (rc)
                        GOTO(out, rc);

                rec = buf;
                idx = le32_to_cpu(rec->lrh_index);
                if (idx < index)
                        CDEBUG(D_HA, "index %u : idx %u\n", index, idx);
                while (idx < index) {
                        rec = ((void *)rec + le32_to_cpu(rec->lrh_len));
                        idx ++;
                }

                /* process records in buffer, starting where we found one */
                while ((void *)rec >= buf) {
                        if (rec->lrh_index == 0)
                                GOTO(out, 0); /* no more records */

                        /* if set, process the callback on this record */
                        if (ext2_test_bit(index, llh->llh_bitmap)) {
                                rc = cb(loghandle, rec, data);
                                if (rc == LLOG_PROC_BREAK) {
                                        CWARN("recovery from log: "LPX64":%x"
                                              " stopped\n",
                                              loghandle->lgh_id.lgl_oid,
                                              loghandle->lgh_id.lgl_ogen);
                                        GOTO(out, rc);
                                }
                                if (rc)
                                        GOTO(out, rc);
                        }

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

                        if ((void *)rec == buf)
                                break;

                        tail = (void *)rec - sizeof(struct llog_rec_tail);
                        rec = ((void *)rec - le32_to_cpu(tail->lrt_len));
                }
        }

 out:
        if (buf)
                OBD_FREE(buf, LLOG_CHUNK_SIZE);
        RETURN(rc);
}
EXPORT_SYMBOL(llog_reverse_process);