fs/gfs2/recovery.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
  * Copyright (C) 2004-2005 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 v.2.
  */

 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/completion.h>
 #include <linux/buffer_head.h>
 #include <asm/semaphore.h>

 #include "gfs2.h"
 #include "bmap.h"
 #include "glock.h"
 #include "glops.h"
 #include "lm.h"
 #include "lops.h"
 #include "meta_io.h"
 #include "recovery.h"
 #include "super.h"

 int gfs2_replay_read_block(struct gfs2_jdesc *jd, unsigned int blk,
 			   struct buffer_head **bh)
 {
 	struct gfs2_glock *gl = get_v2ip(jd->jd_inode)->i_gl;
 	int new = 0;
 	uint64_t dblock;
 	uint32_t extlen;
 	int error;

 	error = gfs2_block_map(get_v2ip(jd->jd_inode), blk, &new, &dblock,
 			       &extlen);
 	if (error)
 		return error;
 	if (!dblock) {
 		gfs2_consist_inode(get_v2ip(jd->jd_inode));
 		return -EIO;
 	}

 	gfs2_meta_ra(gl, dblock, extlen);
 	error = gfs2_meta_read(gl, dblock, DIO_START | DIO_WAIT, bh);

 	return error;
 }

 int gfs2_revoke_add(struct gfs2_sbd *sdp, uint64_t 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_KERNEL);
 	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, uint64_t 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);
 	}
 }

 /**
  * 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 *head)
 {
 	struct buffer_head *bh;
 	struct gfs2_log_header lh;
 	uint32_t hash;
 	int error;

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

 	memcpy(&lh, bh->b_data, sizeof(struct gfs2_log_header));
 	lh.lh_hash = 0;
 	hash = gfs2_disk_hash((char *)&lh, sizeof(struct gfs2_log_header));
 	gfs2_log_header_in(&lh, bh->b_data);

 	brelse(bh);

 	if (lh.lh_header.mh_magic != GFS2_MAGIC ||
 	    lh.lh_header.mh_type != GFS2_METATYPE_LH ||
 	    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 *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(get_v2ip(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 *head)
 {
 	unsigned int blk = head->lh_blkno;
 	struct gfs2_log_header 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(get_v2ip(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 *head)
 {
 	struct gfs2_log_header lh_1, lh_m;
 	uint32_t 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 = get_v2ip(jd->jd_inode)->i_sbd;
 	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 (be16_to_cpu(ld->ld_header.mh_type) == GFS2_METATYPE_LH) {
 			struct gfs2_log_header lh;
 			error = get_log_header(jd, start, &lh);
 			if (!error) {
 				gfs2_replay_incr_blk(sdp, &start);
 				continue;
 			}
 			if (error == 1) {
 				gfs2_consist_inode(get_v2ip(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 *head)
 {
 	struct gfs2_inode *ip = get_v2ip(jd->jd_inode);
 	struct gfs2_sbd *sdp = ip->i_sbd;
 	unsigned int lblock;
 	int new = 0;
 	uint64_t dblock;
 	struct gfs2_log_header *lh;
 	uint32_t hash;
 	struct buffer_head *bh;
 	int error;

 	lblock = head->lh_blkno;
 	gfs2_replay_incr_blk(sdp, &lblock);
 	error = gfs2_block_map(ip, lblock, &new, &dblock, NULL);
 	if (error)
 		return error;
 	if (!dblock) {
 		gfs2_consist_inode(ip);
 		return -EIO;
 	}

 	bh = sb_getblk(sdp->sd_vfs, dblock);
 	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_be16(GFS2_METATYPE_LH);
 	lh->lh_header.mh_format = cpu_to_be16(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;
 }

 /**
  * gfs2_recover_journal - recovery a given journal
  * @jd: the struct gfs2_jdesc describing the journal
  * @wait: Don't return until the journal is clean (or an error is encountered)
  *
  * Acquire the journal's lock, check to see if the journal is clean, and
  * do recovery if necessary.
  *
  * Returns: errno
  */

 int gfs2_recover_journal(struct gfs2_jdesc *jd, int wait)
 {
 	struct gfs2_sbd *sdp = get_v2ip(jd->jd_inode)->i_sbd;
 	struct gfs2_log_header head;
 	struct gfs2_holder j_gh, ji_gh, t_gh;
 	unsigned long t;
 	int ro = 0;
 	unsigned int pass;
 	int error;

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

 	/* Aquire 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 |
 				  ((wait) ? 0 : 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(get_v2ip(jd->jd_inode)->i_gl, LM_ST_SHARED,
 				   LM_FLAG_NOEXP, &ji_gh);
 	if (error)
 		goto fail_gunlock_j;

 	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_NEVER_RECURSE |
 					   GL_NOCANCEL |
 					   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)
 				ro = 1;
 		}

 		if (ro) {
 			fs_warn(sdp, "jid=%u: Can't replay: read-only FS\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_RU(jiffies - t, HZ);

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

 	gfs2_glock_dq_uninit(&ji_gh);

 	gfs2_lm_recovery_done(sdp, jd->jd_jid, LM_RD_SUCCESS);

 	gfs2_glock_dq_uninit(&j_gh);

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

 	return 0;

  fail_gunlock_tr:
 	gfs2_glock_dq_uninit(&t_gh);

  fail_gunlock_ji:
 	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_lm_recovery_done(sdp, jd->jd_jid, LM_RD_GAVEUP);

 	return error;
 }

 /**
  * gfs2_check_journals - Recover any dirty journals
  * @sdp: the filesystem
  *
  */

 void gfs2_check_journals(struct gfs2_sbd *sdp)
 {
 	struct gfs2_jdesc *jd;

 	for (;;) {
 		jd = gfs2_jdesc_find_dirty(sdp);
 		if (!jd)
 			break;

 		if (jd != sdp->sd_jdesc)
 			gfs2_recover_journal(jd, NO_WAIT);
 	}
 }
	/*
	* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
	* Copyright (C) 2004-2005 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 v.2.
	*/

	#include <linux/sched.h>
	#include <linux/slab.h>
	#include <linux/spinlock.h>
	#include <linux/completion.h>
	#include <linux/buffer_head.h>
	#include <asm/semaphore.h>

	#include "gfs2.h"
	#include "bmap.h"
	#include "glock.h"
	#include "glops.h"
	#include "lm.h"
	#include "lops.h"
	#include "meta_io.h"
	#include "recovery.h"
	#include "super.h"

	int gfs2_replay_read_block(struct gfs2_jdesc *jd, unsigned int blk,
	struct buffer_head **bh)
	{
	struct gfs2_glock *gl = get_v2ip(jd->jd_inode)->i_gl;
	int new = 0;
	uint64_t dblock;
	uint32_t extlen;
	int error;

	error = gfs2_block_map(get_v2ip(jd->jd_inode), blk, &new, &dblock,
	&extlen);
	if (error)
	return error;
	if (!dblock) {
	gfs2_consist_inode(get_v2ip(jd->jd_inode));
	return -EIO;
	}

	gfs2_meta_ra(gl, dblock, extlen);
	error = gfs2_meta_read(gl, dblock, DIO_START \| DIO_WAIT, bh);

	return error;
	}

	int gfs2_revoke_add(struct gfs2_sbd *sdp, uint64_t 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_KERNEL);
	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, uint64_t 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);
	}
	}

	/**
	* 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 *head)
	{
	struct buffer_head *bh;
	struct gfs2_log_header lh;
	uint32_t hash;
	int error;

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

	memcpy(&lh, bh->b_data, sizeof(struct gfs2_log_header));
	lh.lh_hash = 0;
	hash = gfs2_disk_hash((char *)&lh, sizeof(struct gfs2_log_header));
	gfs2_log_header_in(&lh, bh->b_data);

	brelse(bh);

	if (lh.lh_header.mh_magic != GFS2_MAGIC \|\|
	lh.lh_header.mh_type != GFS2_METATYPE_LH \|\|
	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 *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(get_v2ip(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 head)
	{
	unsigned int blk = head->lh_blkno;
	struct gfs2_log_header 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(get_v2ip(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 head)
	{
	struct gfs2_log_header lh_1, lh_m;
	uint32_t 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 = get_v2ip(jd->jd_inode)->i_sbd;
	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 (be16_to_cpu(ld->ld_header.mh_type) == GFS2_METATYPE_LH) {
	struct gfs2_log_header lh;
	error = get_log_header(jd, start, &lh);
	if (!error) {
	gfs2_replay_incr_blk(sdp, &start);
	continue;
	}
	if (error == 1) {
	gfs2_consist_inode(get_v2ip(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 head)
	{
	struct gfs2_inode *ip = get_v2ip(jd->jd_inode);
	struct gfs2_sbd *sdp = ip->i_sbd;
	unsigned int lblock;
	int new = 0;
	uint64_t dblock;
	struct gfs2_log_header *lh;
	uint32_t hash;
	struct buffer_head *bh;
	int error;

	lblock = head->lh_blkno;
	gfs2_replay_incr_blk(sdp, &lblock);
	error = gfs2_block_map(ip, lblock, &new, &dblock, NULL);
	if (error)
	return error;
	if (!dblock) {
	gfs2_consist_inode(ip);
	return -EIO;
	}

	bh = sb_getblk(sdp->sd_vfs, dblock);
	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_be16(GFS2_METATYPE_LH);
	lh->lh_header.mh_format = cpu_to_be16(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;
	}

	/**
	* gfs2_recover_journal - recovery a given journal
	* @jd: the struct gfs2_jdesc describing the journal
	* @wait: Don't return until the journal is clean (or an error is encountered)
	*
	* Acquire the journal's lock, check to see if the journal is clean, and
	* do recovery if necessary.
	*
	* Returns: errno
	*/

	int gfs2_recover_journal(struct gfs2_jdesc *jd, int wait)
	{
	struct gfs2_sbd *sdp = get_v2ip(jd->jd_inode)->i_sbd;
	struct gfs2_log_header head;
	struct gfs2_holder j_gh, ji_gh, t_gh;
	unsigned long t;
	int ro = 0;
	unsigned int pass;
	int error;

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

	/* Aquire 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 \|
	((wait) ? 0 : 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(get_v2ip(jd->jd_inode)->i_gl, LM_ST_SHARED,
	LM_FLAG_NOEXP, &ji_gh);
	if (error)
	goto fail_gunlock_j;

	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_NEVER_RECURSE \|
	GL_NOCANCEL \|
	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)
	ro = 1;
	}

	if (ro) {
	fs_warn(sdp, "jid=%u: Can't replay: read-only FS\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_RU(jiffies - t, HZ);

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

	gfs2_glock_dq_uninit(&ji_gh);

	gfs2_lm_recovery_done(sdp, jd->jd_jid, LM_RD_SUCCESS);

	gfs2_glock_dq_uninit(&j_gh);

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

	return 0;

	fail_gunlock_tr:
	gfs2_glock_dq_uninit(&t_gh);

	fail_gunlock_ji:
	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_lm_recovery_done(sdp, jd->jd_jid, LM_RD_GAVEUP);

	return error;
	}

	/**
	* gfs2_check_journals - Recover any dirty journals
	* @sdp: the filesystem
	*
	*/

	void gfs2_check_journals(struct gfs2_sbd *sdp)
	{
	struct gfs2_jdesc *jd;

	for (;;) {
	jd = gfs2_jdesc_find_dirty(sdp);
	if (!jd)
	break;

	if (jd != sdp->sd_jdesc)
	gfs2_recover_journal(jd, NO_WAIT);
	}
	}