/*
 * 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/slow-work.h>

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

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_sbd *sdp, u64 blkno, unsigned int where)
{
        struct list_head *head = &sdp->sd_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_sbd *sdp, u64 blkno, unsigned int where)
{
        struct gfs2_revoke_replay *rr;
        int wrap, a, b, revoke;
        int found = 0;

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

        if (!found)
                return 0;

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

        return revoke;
}

void gfs2_revoke_clean(struct gfs2_sbd *sdp)
{
        struct list_head *head = &sdp->sd_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);
        }
}

static int gfs2_log_header_in(struct gfs2_log_header_host *lh, const void *buf)
{
        const struct gfs2_log_header *str = buf;

        if (str->lh_header.mh_magic != cpu_to_be32(GFS2_MAGIC) ||
            str->lh_header.mh_type != cpu_to_be32(GFS2_METATYPE_LH))
                return 1;

        lh->lh_sequence = be64_to_cpu(str->lh_sequence);
        lh->lh_flags = be32_to_cpu(str->lh_flags);
        lh->lh_tail = be32_to_cpu(str->lh_tail);
        lh->lh_blkno = be32_to_cpu(str->lh_blkno);
        lh->lh_hash = be32_to_cpu(str->lh_hash);
        return 0;
}

/**
 * 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 buffer_head *bh;
        struct gfs2_log_header_host uninitialized_var(lh);
        const u32 nothing = 0;
        u32 hash;
        int error;

        error = gfs2_replay_read_block(jd, blk, &bh);
        if (error)
                return error;

        hash = crc32_le((u32)~0, bh->b_data, sizeof(struct gfs2_log_header) -
                                             sizeof(u32));
        hash = crc32_le(hash, (unsigned char const *)&nothing, sizeof(nothing));
        hash ^= (u32)~0;
        error = gfs2_log_header_in(&lh, bh->b_data);
        brelse(bh);

        if (error || lh.lh_blkno != blk || lh.lh_hash != hash)
                return 1;

        *head = lh;

        return 0;
}

/**
 * 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, unsigned int 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(sdp, &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(sdp, &start);

                brelse(bh);
        }

        return 0;
}

/**
 * clean_journal - mark a dirty journal as being clean
 * @sdp: the filesystem
 * @jd: the journal
 * @gl: the journal's glock
 * @head: the head journal to start from
 *
 * Returns: errno
 */

static int clean_journal(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head)
{
        struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
        unsigned int lblock;
        struct gfs2_log_header *lh;
        u32 hash;
        struct buffer_head *bh;
        int error;
        struct buffer_head bh_map = { .b_state = 0, .b_blocknr = 0 };

        lblock = head->lh_blkno;
        gfs2_replay_incr_blk(sdp, &lblock);
        bh_map.b_size = 1 << ip->i_inode.i_blkbits;
        error = gfs2_block_map(&ip->i_inode, lblock, &bh_map, 0);
        if (error)
                return error;
        if (!bh_map.b_blocknr) {
                gfs2_consist_inode(ip);
                return -EIO;
        }

        bh = sb_getblk(sdp->sd_vfs, bh_map.b_blocknr);
        lock_buffer(bh);
        memset(bh->b_data, 0, bh->b_size);
        set_buffer_uptodate(bh);
        clear_buffer_dirty(bh);
        unlock_buffer(bh);

        lh = (struct gfs2_log_header *)bh->b_data;
        memset(lh, 0, sizeof(struct gfs2_log_header));
        lh->lh_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
        lh->lh_header.mh_type = cpu_to_be32(GFS2_METATYPE_LH);
        lh->lh_header.mh_format = cpu_to_be32(GFS2_FORMAT_LH);
        lh->lh_sequence = cpu_to_be64(head->lh_sequence + 1);
        lh->lh_flags = cpu_to_be32(GFS2_LOG_HEAD_UNMOUNT);
        lh->lh_blkno = cpu_to_be32(lblock);
        hash = gfs2_disk_hash((const char *)lh, sizeof(struct gfs2_log_header));
        lh->lh_hash = cpu_to_be32(hash);

        set_buffer_dirty(bh);
        if (sync_dirty_buffer(bh))
                gfs2_io_error_bh(sdp, bh);
        brelse(bh);

        return error;
}


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=%d", jid);
        sprintf(env_status, "RECOVERY=%s",
                message == LM_RD_SUCCESS ? "Done" : "Failed");
        kobject_uevent_env(&sdp->sd_kobj, KOBJ_CHANGE, envp);
}

static int gfs2_recover_get_ref(struct slow_work *work)
{
        struct gfs2_jdesc *jd = container_of(work, struct gfs2_jdesc, jd_work);
        if (test_and_set_bit(JDF_RECOVERY, &jd->jd_flags))
                return -EBUSY;
        return 0;
}

static void gfs2_recover_put_ref(struct slow_work *work)
{
        struct gfs2_jdesc *jd = container_of(work, struct gfs2_jdesc, jd_work);
        clear_bit(JDF_RECOVERY, &jd->jd_flags);
        smp_mb__after_clear_bit();
        wake_up_bit(&jd->jd_flags, JDF_RECOVERY);
}

static void gfs2_recover_work(struct slow_work *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, t_gh;
        unsigned long t;
        int ro = 0;
        unsigned int pass;
        int error;

        if (jd->jd_jid != sdp->sd_lockstruct.ls_jid) {
                fs_info(sdp, "jid=%u: Trying to acquire journal lock...\n",
                        jd->jd_jid);

                /* 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);
        }

        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;

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

                t = jiffies;

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

                error = gfs2_glock_nq_init(sdp->sd_trans_gl, LM_ST_SHARED,
                                           LM_FLAG_NOEXP | LM_FLAG_PRIORITY |
                                           GL_NOCACHE, &t_gh);
                if (error)
                        goto fail_gunlock_ji;

                if (test_bit(SDF_JOURNAL_CHECKED, &sdp->sd_flags)) {
                        if (!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
                                ro = 1;
                } else {
                        if (sdp->sd_vfs->s_flags & MS_RDONLY) {
                                /* 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_tr;
                }

                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_tr;
                }

                error = clean_journal(jd, &head);
                if (error)
                        goto fail_gunlock_tr;

                gfs2_glock_dq_uninit(&t_gh);
                t = DIV_ROUND_UP(jiffies - t, HZ);
                fs_info(sdp, "jid=%u: Journal replayed in %lus\n",
                        jd->jd_jid, t);
        }

        if (jd->jd_jid != sdp->sd_lockstruct.ls_jid)
                gfs2_glock_dq_uninit(&ji_gh);

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

        if (jd->jd_jid != sdp->sd_lockstruct.ls_jid)
                gfs2_glock_dq_uninit(&j_gh);

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

fail_gunlock_tr:
        gfs2_glock_dq_uninit(&t_gh);
fail_gunlock_ji:
        if (jd->jd_jid != sdp->sd_lockstruct.ls_jid) {
                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:
        gfs2_recovery_done(sdp, jd->jd_jid, LM_RD_GAVEUP);
}

struct slow_work_ops gfs2_recover_ops = {
        .owner   = THIS_MODULE,
        .get_ref = gfs2_recover_get_ref,
        .put_ref = gfs2_recover_put_ref,
        .execute = gfs2_recover_work,
};


static int gfs2_recovery_wait(void *word)
{
        schedule();
        return 0;
}

int gfs2_recover_journal(struct gfs2_jdesc *jd)
{
        int rv;
        rv = slow_work_enqueue(&jd->jd_work);
        if (rv)
                return rv;
        wait_on_bit(&jd->jd_flags, JDF_RECOVERY, gfs2_recovery_wait, TASK_UNINTERRUPTIBLE);
        return 0;
}