/*
   * 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 "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"

  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);
  	}
  }

  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(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
   * @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(jd, &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.__pad0 = cpu_to_be64(0);

  	lh->lh_header.mh_format = cpu_to_be32(GFS2_FORMAT_LH);

  	lh->lh_header.mh_jid = cpu_to_be32(sdp->sd_jdesc->jd_jid);

  	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=%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;

  	unsigned long t;
  	int ro = 0;
  	unsigned int pass;
  	int error;

  	int jlocked = 0;

  	if (sdp->sd_args.ar_spectator ||
  	    (jd->jd_jid != sdp->sd_lockstruct.ls_jid)) {

  		fs_info(sdp, "jid=%u: Trying to acquire journal lock...
  ",
  			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
  ", 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
  ", jd->jd_jid);
  	}

  
  	fs_info(sdp, "jid=%u: Looking at journal...
  ", 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...
  ",
  			jd->jd_jid);
  
  		t = jiffies;

  		/* 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 (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.
  ");
  					fs_info(sdp, "write access will be "
  						"enabled during recovery.
  ");
  				}
  			}

  		}
  
  		if (ro) {

  			fs_warn(sdp, "jid=%u: Can't replay: read-only block "
  				"device
  ", jd->jd_jid);

  			error = -EROFS;

  			goto fail_gunlock_thaw;

  		}
  
  		fs_info(sdp, "jid=%u: Replaying journal...
  ", 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;

  		}
  
  		error = clean_journal(jd, &head);
  		if (error)

  			goto fail_gunlock_thaw;

  		gfs2_glock_dq_uninit(&thaw_gh);

  		t = DIV_ROUND_UP(jiffies - t, HZ);

  		fs_info(sdp, "jid=%u: Journal replayed in %lus
  ",
  			jd->jd_jid, t);
  	}

  	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
  ", 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
  ", 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;

  }