/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/gfs2_ondisk.h>
#include <linux/crc32.h>
#include <linux/crc32c.h>
#include <linux/ktime.h>

#include "gfs2.h"
#include "incore.h"
#include "bmap.h"
#include "glock.h"
#include "glops.h"
#include "log.h"
#include "lops.h"
#include "meta_io.h"
#include "recovery.h"
#include "super.h"
#include "util.h"
#include "dir.h"

struct workqueue_struct *gfs_recovery_wq;

int gfs2_replay_read_block(struct gfs2_jdesc *jd, unsigned int blk,
                           struct buffer_head **bh)
{
        struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
        struct gfs2_glock *gl = ip->i_gl;
        int new = 0;
        u64 dblock;
        u32 extlen;
        int error;

        error = gfs2_extent_map(&ip->i_inode, blk, &new, &dblock, &extlen);
        if (error)
                return error;
        if (!dblock) {
                gfs2_consist_inode(ip);
                return -EIO;
        }

        *bh = gfs2_meta_ra(gl, dblock, extlen);

        return error;
}

int gfs2_revoke_add(struct gfs2_jdesc *jd, u64 blkno, unsigned int where)
{
        struct list_head *head = &jd->jd_revoke_list;
        struct gfs2_revoke_replay *rr;
        int found = 0;

        list_for_each_entry(rr, head, rr_list) {
                if (rr->rr_blkno == blkno) {
                        found = 1;
                        break;
                }
        }

        if (found) {
                rr->rr_where = where;
                return 0;
        }

        rr = kmalloc(sizeof(struct gfs2_revoke_replay), GFP_NOFS);
        if (!rr)
                return -ENOMEM;

        rr->rr_blkno = blkno;
        rr->rr_where = where;
        list_add(&rr->rr_list, head);

        return 1;
}

int gfs2_revoke_check(struct gfs2_jdesc *jd, u64 blkno, unsigned int where)
{
        struct gfs2_revoke_replay *rr;
        int wrap, a, b, revoke;
        int found = 0;

        list_for_each_entry(rr, &jd->jd_revoke_list, rr_list) {
                if (rr->rr_blkno == blkno) {
                        found = 1;
                        break;
                }
        }

        if (!found)
                return 0;

        wrap = (rr->rr_where < jd->jd_replay_tail);
        a = (jd->jd_replay_tail < where);
        b = (where < rr->rr_where);
        revoke = (wrap) ? (a || b) : (a && b);

        return revoke;
}

void gfs2_revoke_clean(struct gfs2_jdesc *jd)
{
        struct list_head *head = &jd->jd_revoke_list;
        struct gfs2_revoke_replay *rr;

        while (!list_empty(head)) {
                rr = list_entry(head->next, struct gfs2_revoke_replay, rr_list);
                list_del(&rr->rr_list);
                kfree(rr);
        }
}

/**
 * get_log_header - read the log header for a given segment
 * @jd: the journal
 * @blk: the block to look at
 * @lh: the log header to return
 *
 * Read the log header for a given segement in a given journal.  Do a few
 * sanity checks on it.
 *
 * Returns: 0 on success,
 *          1 if the header was invalid or incomplete,
 *          errno on error
 */

static int get_log_header(struct gfs2_jdesc *jd, unsigned int blk,
                          struct gfs2_log_header_host *head)
{
        struct gfs2_log_header *lh;
        struct buffer_head *bh;
        u32 hash, crc;
        int error;

        error = gfs2_replay_read_block(jd, blk, &bh);
        if (error)
                return error;
        lh = (void *)bh->b_data;

        hash = crc32(~0, lh, LH_V1_SIZE - 4);
        hash = ~crc32_le_shift(hash, 4);  /* assume lh_hash is zero */

        crc = crc32c(~0, (void *)lh + LH_V1_SIZE + 4,
                     bh->b_size - LH_V1_SIZE - 4);

        error = lh->lh_header.mh_magic != cpu_to_be32(GFS2_MAGIC) ||
                lh->lh_header.mh_type != cpu_to_be32(GFS2_METATYPE_LH) ||
                be32_to_cpu(lh->lh_blkno) != blk ||
                be32_to_cpu(lh->lh_hash) != hash ||
                (lh->lh_crc != 0 && be32_to_cpu(lh->lh_crc) != crc);

        brelse(bh);

        if (!error) {
                head->lh_sequence = be64_to_cpu(lh->lh_sequence);
                head->lh_flags = be32_to_cpu(lh->lh_flags);
                head->lh_tail = be32_to_cpu(lh->lh_tail);
                head->lh_blkno = be32_to_cpu(lh->lh_blkno);
        }
        return error;
}

/**
 * find_good_lh - find a good log header
 * @jd: the journal
 * @blk: the segment to start searching from
 * @lh: the log header to fill in
 * @forward: if true search forward in the log, else search backward
 *
 * Call get_log_header() to get a log header for a segment, but if the
 * segment is bad, either scan forward or backward until we find a good one.
 *
 * Returns: errno
 */

static int find_good_lh(struct gfs2_jdesc *jd, unsigned int *blk,
                        struct gfs2_log_header_host *head)
{
        unsigned int orig_blk = *blk;
        int error;

        for (;;) {
                error = get_log_header(jd, *blk, head);
                if (error <= 0)
                        return error;

                if (++*blk == jd->jd_blocks)
                        *blk = 0;

                if (*blk == orig_blk) {
                        gfs2_consist_inode(GFS2_I(jd->jd_inode));
                        return -EIO;
                }
        }
}

/**
 * jhead_scan - make sure we've found the head of the log
 * @jd: the journal
 * @head: this is filled in with the log descriptor of the head
 *
 * At this point, seg and lh should be either the head of the log or just
 * before.  Scan forward until we find the head.
 *
 * Returns: errno
 */

static int jhead_scan(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head)
{
        unsigned int blk = head->lh_blkno;
        struct gfs2_log_header_host lh;
        int error;

        for (;;) {
                if (++blk == jd->jd_blocks)
                        blk = 0;

                error = get_log_header(jd, blk, &lh);
                if (error < 0)
                        return error;
                if (error == 1)
                        continue;

                if (lh.lh_sequence == head->lh_sequence) {
                        gfs2_consist_inode(GFS2_I(jd->jd_inode));
                        return -EIO;
                }
                if (lh.lh_sequence < head->lh_sequence)
                        break;

                *head = lh;
        }

        return 0;
}

/**
 * gfs2_find_jhead - find the head of a log
 * @jd: the journal
 * @head: the log descriptor for the head of the log is returned here
 *
 * Do a binary search of a journal and find the valid log entry with the
 * highest sequence number.  (i.e. the log head)
 *
 * Returns: errno
 */

int gfs2_find_jhead(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head)
{
        struct gfs2_log_header_host lh_1, lh_m;
        u32 blk_1, blk_2, blk_m;
        int error;

        blk_1 = 0;
        blk_2 = jd->jd_blocks - 1;

        for (;;) {
                blk_m = (blk_1 + blk_2) / 2;

                error = find_good_lh(jd, &blk_1, &lh_1);
                if (error)
                        return error;

                error = find_good_lh(jd, &blk_m, &lh_m);
                if (error)
                        return error;

                if (blk_1 == blk_m || blk_m == blk_2)
                        break;

                if (lh_1.lh_sequence <= lh_m.lh_sequence)
                        blk_1 = blk_m;
                else
                        blk_2 = blk_m;
        }

        error = jhead_scan(jd, &lh_1);
        if (error)
                return error;

        *head = lh_1;

        return error;
}

/**
 * foreach_descriptor - go through the active part of the log
 * @jd: the journal
 * @start: the first log header in the active region
 * @end: the last log header (don't process the contents of this entry))
 *
 * Call a given function once for every log descriptor in the active
 * portion of the log.
 *
 * Returns: errno
 */

static int foreach_descriptor(struct gfs2_jdesc *jd, u32 start,
                              unsigned int end, int pass)
{
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
        struct buffer_head *bh;
        struct gfs2_log_descriptor *ld;
        int error = 0;
        u32 length;
        __be64 *ptr;
        unsigned int offset = sizeof(struct gfs2_log_descriptor);
        offset += sizeof(__be64) - 1;
        offset &= ~(sizeof(__be64) - 1);

        while (start != end) {
                error = gfs2_replay_read_block(jd, start, &bh);
                if (error)
                        return error;
                if (gfs2_meta_check(sdp, bh)) {
                        brelse(bh);
                        return -EIO;
                }
                ld = (struct gfs2_log_descriptor *)bh->b_data;
                length = be32_to_cpu(ld->ld_length);

                if (be32_to_cpu(ld->ld_header.mh_type) == GFS2_METATYPE_LH) {
                        struct gfs2_log_header_host lh;
                        error = get_log_header(jd, start, &lh);
                        if (!error) {
                                gfs2_replay_incr_blk(jd, &start);
                                brelse(bh);
                                continue;
                        }
                        if (error == 1) {
                                gfs2_consist_inode(GFS2_I(jd->jd_inode));
                                error = -EIO;
                        }
                        brelse(bh);
                        return error;
                } else if (gfs2_metatype_check(sdp, bh, GFS2_METATYPE_LD)) {
                        brelse(bh);
                        return -EIO;
                }
                ptr = (__be64 *)(bh->b_data + offset);
                error = lops_scan_elements(jd, start, ld, ptr, pass);
                if (error) {
                        brelse(bh);
                        return error;
                }

                while (length--)
                        gfs2_replay_incr_blk(jd, &start);

                brelse(bh);
        }

        return 0;
}

/**
 * clean_journal - mark a dirty journal as being clean
 * @jd: the journal
 * @head: the head journal to start from
 *
 * Returns: errno
 */

static void clean_journal(struct gfs2_jdesc *jd,
                          struct gfs2_log_header_host *head)
{
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
        u32 lblock = head->lh_blkno;

        gfs2_replay_incr_blk(jd, &lblock);
        if (jd->jd_jid == sdp->sd_lockstruct.ls_jid)
                sdp->sd_log_flush_head = lblock;
        gfs2_write_log_header(sdp, jd, head->lh_sequence + 1, 0, lblock,
                              GFS2_LOG_HEAD_UNMOUNT | GFS2_LOG_HEAD_RECOVERY,
                              REQ_PREFLUSH | REQ_FUA | REQ_META | REQ_SYNC);
}


static void gfs2_recovery_done(struct gfs2_sbd *sdp, unsigned int jid,
                               unsigned int message)
{
        char env_jid[20];
        char env_status[20];
        char *envp[] = { env_jid, env_status, NULL };
        struct lm_lockstruct *ls = &sdp->sd_lockstruct;

        ls->ls_recover_jid_done = jid;
        ls->ls_recover_jid_status = message;
        sprintf(env_jid, "JID=%u", jid);
        sprintf(env_status, "RECOVERY=%s",
                message == LM_RD_SUCCESS ? "Done" : "Failed");
        kobject_uevent_env(&sdp->sd_kobj, KOBJ_CHANGE, envp);

        if (sdp->sd_lockstruct.ls_ops->lm_recovery_result)
                sdp->sd_lockstruct.ls_ops->lm_recovery_result(sdp, jid, message);
}

void gfs2_recover_func(struct work_struct *work)
{
        struct gfs2_jdesc *jd = container_of(work, struct gfs2_jdesc, jd_work);
        struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
        struct gfs2_log_header_host head;
        struct gfs2_holder j_gh, ji_gh, thaw_gh;
        ktime_t t_start, t_jlck, t_jhd, t_tlck, t_rep;
        int ro = 0;
        unsigned int pass;
        int error = 0;
        int jlocked = 0;

        t_start = ktime_get();
        if (sdp->sd_args.ar_spectator)
                goto fail;
        if (jd->jd_jid != sdp->sd_lockstruct.ls_jid) {
                fs_info(sdp, "jid=%u: Trying to acquire journal lock...\n",
                        jd->jd_jid);
                jlocked = 1;
                /* Acquire the journal lock so we can do recovery */

                error = gfs2_glock_nq_num(sdp, jd->jd_jid, &gfs2_journal_glops,
                                          LM_ST_EXCLUSIVE,
                                          LM_FLAG_NOEXP | LM_FLAG_TRY | GL_NOCACHE,
                                          &j_gh);
                switch (error) {
                case 0:
                        break;

                case GLR_TRYFAILED:
                        fs_info(sdp, "jid=%u: Busy\n", jd->jd_jid);
                        error = 0;

                default:
                        goto fail;
                };

                error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED,
                                           LM_FLAG_NOEXP | GL_NOCACHE, &ji_gh);
                if (error)
                        goto fail_gunlock_j;
        } else {
                fs_info(sdp, "jid=%u, already locked for use\n", jd->jd_jid);
        }

        t_jlck = ktime_get();
        fs_info(sdp, "jid=%u: Looking at journal...\n", jd->jd_jid);

        error = gfs2_jdesc_check(jd);
        if (error)
                goto fail_gunlock_ji;

        error = gfs2_find_jhead(jd, &head);
        if (error)
                goto fail_gunlock_ji;
        t_jhd = ktime_get();

        if (!(head.lh_flags & GFS2_LOG_HEAD_UNMOUNT)) {
                fs_info(sdp, "jid=%u: Acquiring the transaction lock...\n",
                        jd->jd_jid);

                /* Acquire a shared hold on the freeze lock */

                error = gfs2_glock_nq_init(sdp->sd_freeze_gl, LM_ST_SHARED,
                                           LM_FLAG_NOEXP | LM_FLAG_PRIORITY,
                                           &thaw_gh);
                if (error)
                        goto fail_gunlock_ji;

                if (test_bit(SDF_RORECOVERY, &sdp->sd_flags)) {
                        ro = 1;
                } else if (test_bit(SDF_JOURNAL_CHECKED, &sdp->sd_flags)) {
                        if (!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
                                ro = 1;
                } else {
                        if (sb_rdonly(sdp->sd_vfs)) {
                                /* check if device itself is read-only */
                                ro = bdev_read_only(sdp->sd_vfs->s_bdev);
                                if (!ro) {
                                        fs_info(sdp, "recovery required on "
                                                "read-only filesystem.\n");
                                        fs_info(sdp, "write access will be "
                                                "enabled during recovery.\n");
                                }
                        }
                }

                if (ro) {
                        fs_warn(sdp, "jid=%u: Can't replay: read-only block "
                                "device\n", jd->jd_jid);
                        error = -EROFS;
                        goto fail_gunlock_thaw;
                }

                t_tlck = ktime_get();
                fs_info(sdp, "jid=%u: Replaying journal...\n", jd->jd_jid);

                for (pass = 0; pass < 2; pass++) {
                        lops_before_scan(jd, &head, pass);
                        error = foreach_descriptor(jd, head.lh_tail,
                                                   head.lh_blkno, pass);
                        lops_after_scan(jd, error, pass);
                        if (error)
                                goto fail_gunlock_thaw;
                }

                clean_journal(jd, &head);

                gfs2_glock_dq_uninit(&thaw_gh);
                t_rep = ktime_get();
                fs_info(sdp, "jid=%u: Journal replayed in %lldms [jlck:%lldms, "
                        "jhead:%lldms, tlck:%lldms, replay:%lldms]\n",
                        jd->jd_jid, ktime_ms_delta(t_rep, t_start),
                        ktime_ms_delta(t_jlck, t_start),
                        ktime_ms_delta(t_jhd, t_jlck),
                        ktime_ms_delta(t_tlck, t_jhd),
                        ktime_ms_delta(t_rep, t_tlck));
        }

        gfs2_recovery_done(sdp, jd->jd_jid, LM_RD_SUCCESS);

        if (jlocked) {
                gfs2_glock_dq_uninit(&ji_gh);
                gfs2_glock_dq_uninit(&j_gh);
        }

        fs_info(sdp, "jid=%u: Done\n", jd->jd_jid);
        goto done;

fail_gunlock_thaw:
        gfs2_glock_dq_uninit(&thaw_gh);
fail_gunlock_ji:
        if (jlocked) {
                gfs2_glock_dq_uninit(&ji_gh);
fail_gunlock_j:
                gfs2_glock_dq_uninit(&j_gh);
        }

        fs_info(sdp, "jid=%u: %s\n", jd->jd_jid, (error) ? "Failed" : "Done");
fail:
        jd->jd_recover_error = error;
        gfs2_recovery_done(sdp, jd->jd_jid, LM_RD_GAVEUP);
done:
        clear_bit(JDF_RECOVERY, &jd->jd_flags);
        smp_mb__after_atomic();
        wake_up_bit(&jd->jd_flags, JDF_RECOVERY);
}

int gfs2_recover_journal(struct gfs2_jdesc *jd, bool wait)
{
        int rv;

        if (test_and_set_bit(JDF_RECOVERY, &jd->jd_flags))
                return -EBUSY;

        /* we have JDF_RECOVERY, queue should always succeed */
        rv = queue_work(gfs_recovery_wq, &jd->jd_work);
        BUG_ON(!rv);

        if (wait)
                wait_on_bit(&jd->jd_flags, JDF_RECOVERY,
                            TASK_UNINTERRUPTIBLE);

        return wait ? jd->jd_recover_error : 0;
}