fs/gfs2/lops.c - kernel/msm-4.9 - Gitiles

 /*
  * 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/sched.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/bio.h>
 #include <linux/fs.h>

 #include "gfs2.h"
 #include "incore.h"
 #include "inode.h"
 #include "glock.h"
 #include "log.h"
 #include "lops.h"
 #include "meta_io.h"
 #include "recovery.h"
 #include "rgrp.h"
 #include "trans.h"
 #include "util.h"
 #include "trace_gfs2.h"

 /**
  * gfs2_pin - Pin a buffer in memory
  * @sdp: The superblock
  * @bh: The buffer to be pinned
  *
  * The log lock must be held when calling this function
  */
 static void gfs2_pin(struct gfs2_sbd *sdp, struct buffer_head *bh)
 {
 	struct gfs2_bufdata *bd;

 	gfs2_assert_withdraw(sdp, test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags));

 	clear_buffer_dirty(bh);
 	if (test_set_buffer_pinned(bh))
 		gfs2_assert_withdraw(sdp, 0);
 	if (!buffer_uptodate(bh))
 		gfs2_io_error_bh(sdp, bh);
 	bd = bh->b_private;
 	/* If this buffer is in the AIL and it has already been written
 	 * to in-place disk block, remove it from the AIL.
 	 */
 	spin_lock(&sdp->sd_ail_lock);
 	if (bd->bd_ail)
 		list_move(&bd->bd_ail_st_list, &bd->bd_ail->ai_ail2_list);
 	spin_unlock(&sdp->sd_ail_lock);
 	get_bh(bh);
 	atomic_inc(&sdp->sd_log_pinned);
 	trace_gfs2_pin(bd, 1);
 }

 /**
  * gfs2_unpin - Unpin a buffer
  * @sdp: the filesystem the buffer belongs to
  * @bh: The buffer to unpin
  * @ai:
  *
  */

 static void gfs2_unpin(struct gfs2_sbd *sdp, struct buffer_head *bh,
 		       struct gfs2_ail *ai)
 {
 	struct gfs2_bufdata *bd = bh->b_private;

 	gfs2_assert_withdraw(sdp, buffer_uptodate(bh));

 	if (!buffer_pinned(bh))
 		gfs2_assert_withdraw(sdp, 0);

 	lock_buffer(bh);
 	mark_buffer_dirty(bh);
 	clear_buffer_pinned(bh);

 	spin_lock(&sdp->sd_ail_lock);
 	if (bd->bd_ail) {
 		list_del(&bd->bd_ail_st_list);
 		brelse(bh);
 	} else {
 		struct gfs2_glock *gl = bd->bd_gl;
 		list_add(&bd->bd_ail_gl_list, &gl->gl_ail_list);
 		atomic_inc(&gl->gl_ail_count);
 	}
 	bd->bd_ail = ai;
 	list_add(&bd->bd_ail_st_list, &ai->ai_ail1_list);
 	spin_unlock(&sdp->sd_ail_lock);

 	if (test_and_clear_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags))
 		gfs2_glock_schedule_for_reclaim(bd->bd_gl);
 	trace_gfs2_pin(bd, 0);
 	unlock_buffer(bh);
 	atomic_dec(&sdp->sd_log_pinned);
 }


 static inline struct gfs2_log_descriptor *bh_log_desc(struct buffer_head *bh)
 {
 	return (struct gfs2_log_descriptor *)bh->b_data;
 }

 static inline __be64 *bh_log_ptr(struct buffer_head *bh)
 {
 	struct gfs2_log_descriptor *ld = bh_log_desc(bh);
 	return (__force __be64 *)(ld + 1);
 }

 static inline __be64 *bh_ptr_end(struct buffer_head *bh)
 {
 	return (__force __be64 *)(bh->b_data + bh->b_size);
 }


 static struct buffer_head *gfs2_get_log_desc(struct gfs2_sbd *sdp, u32 ld_type)
 {
 	struct buffer_head *bh = gfs2_log_get_buf(sdp);
 	struct gfs2_log_descriptor *ld = bh_log_desc(bh);
 	ld->ld_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
 	ld->ld_header.mh_type = cpu_to_be32(GFS2_METATYPE_LD);
 	ld->ld_header.mh_format = cpu_to_be32(GFS2_FORMAT_LD);
 	ld->ld_type = cpu_to_be32(ld_type);
 	ld->ld_length = 0;
 	ld->ld_data1 = 0;
 	ld->ld_data2 = 0;
 	memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));
 	return bh;
 }

 static void buf_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
 {
 	struct gfs2_bufdata *bd = container_of(le, struct gfs2_bufdata, bd_le);
 	struct gfs2_meta_header *mh;
 	struct gfs2_trans *tr;

 	lock_buffer(bd->bd_bh);
 	gfs2_log_lock(sdp);
 	if (!list_empty(&bd->bd_list_tr))
 		goto out;
 	tr = current->journal_info;
 	tr->tr_touched = 1;
 	tr->tr_num_buf++;
 	list_add(&bd->bd_list_tr, &tr->tr_list_buf);
 	if (!list_empty(&le->le_list))
 		goto out;
 	set_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
 	set_bit(GLF_DIRTY, &bd->bd_gl->gl_flags);
 	gfs2_meta_check(sdp, bd->bd_bh);
 	gfs2_pin(sdp, bd->bd_bh);
 	mh = (struct gfs2_meta_header *)bd->bd_bh->b_data;
 	mh->__pad0 = cpu_to_be64(0);
 	mh->mh_jid = cpu_to_be32(sdp->sd_jdesc->jd_jid);
 	sdp->sd_log_num_buf++;
 	list_add(&le->le_list, &sdp->sd_log_le_buf);
 	tr->tr_num_buf_new++;
 out:
 	gfs2_log_unlock(sdp);
 	unlock_buffer(bd->bd_bh);
 }

 static void buf_lo_before_commit(struct gfs2_sbd *sdp)
 {
 	struct buffer_head *bh;
 	struct gfs2_log_descriptor *ld;
 	struct gfs2_bufdata *bd1 = NULL, *bd2;
 	unsigned int total;
 	unsigned int limit;
 	unsigned int num;
 	unsigned n;
 	__be64 *ptr;

 	limit = buf_limit(sdp);
 	/* for 4k blocks, limit = 503 */

 	gfs2_log_lock(sdp);
 	total = sdp->sd_log_num_buf;
 	bd1 = bd2 = list_prepare_entry(bd1, &sdp->sd_log_le_buf, bd_le.le_list);
 	while(total) {
 		num = total;
 		if (total > limit)
 			num = limit;
 		gfs2_log_unlock(sdp);
 		bh = gfs2_get_log_desc(sdp, GFS2_LOG_DESC_METADATA);
 		gfs2_log_lock(sdp);
 		ld = bh_log_desc(bh);
 		ptr = bh_log_ptr(bh);
 		ld->ld_length = cpu_to_be32(num + 1);
 		ld->ld_data1 = cpu_to_be32(num);

 		n = 0;
 		list_for_each_entry_continue(bd1, &sdp->sd_log_le_buf,
 					     bd_le.le_list) {
 			*ptr++ = cpu_to_be64(bd1->bd_bh->b_blocknr);
 			if (++n >= num)
 				break;
 		}

 		gfs2_log_unlock(sdp);
 		submit_bh(WRITE_SYNC, bh);
 		gfs2_log_lock(sdp);

 		n = 0;
 		list_for_each_entry_continue(bd2, &sdp->sd_log_le_buf,
 					     bd_le.le_list) {
 			get_bh(bd2->bd_bh);
 			gfs2_log_unlock(sdp);
 			lock_buffer(bd2->bd_bh);
 			bh = gfs2_log_fake_buf(sdp, bd2->bd_bh);
 			submit_bh(WRITE_SYNC, bh);
 			gfs2_log_lock(sdp);
 			if (++n >= num)
 				break;
 		}

 		BUG_ON(total < num);
 		total -= num;
 	}
 	gfs2_log_unlock(sdp);
 }

 static void buf_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
 {
 	struct list_head *head = &sdp->sd_log_le_buf;
 	struct gfs2_bufdata *bd;

 	while (!list_empty(head)) {
 		bd = list_entry(head->next, struct gfs2_bufdata, bd_le.le_list);
 		list_del_init(&bd->bd_le.le_list);
 		sdp->sd_log_num_buf--;

 		gfs2_unpin(sdp, bd->bd_bh, ai);
 	}
 	gfs2_assert_warn(sdp, !sdp->sd_log_num_buf);
 }

 static void buf_lo_before_scan(struct gfs2_jdesc *jd,
 			       struct gfs2_log_header_host *head, int pass)
 {
 	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

 	if (pass != 0)
 		return;

 	sdp->sd_found_blocks = 0;
 	sdp->sd_replayed_blocks = 0;
 }

 static int buf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
 				struct gfs2_log_descriptor *ld, __be64 *ptr,
 				int pass)
 {
 	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
 	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 	struct gfs2_glock *gl = ip->i_gl;
 	unsigned int blks = be32_to_cpu(ld->ld_data1);
 	struct buffer_head *bh_log, *bh_ip;
 	u64 blkno;
 	int error = 0;

 	if (pass != 1 || be32_to_cpu(ld->ld_type) != GFS2_LOG_DESC_METADATA)
 		return 0;

 	gfs2_replay_incr_blk(sdp, &start);

 	for (; blks; gfs2_replay_incr_blk(sdp, &start), blks--) {
 		blkno = be64_to_cpu(*ptr++);

 		sdp->sd_found_blocks++;

 		if (gfs2_revoke_check(sdp, blkno, start))
 			continue;

 		error = gfs2_replay_read_block(jd, start, &bh_log);
 		if (error)
 			return error;

 		bh_ip = gfs2_meta_new(gl, blkno);
 		memcpy(bh_ip->b_data, bh_log->b_data, bh_log->b_size);

 		if (gfs2_meta_check(sdp, bh_ip))
 			error = -EIO;
 		else
 			mark_buffer_dirty(bh_ip);

 		brelse(bh_log);
 		brelse(bh_ip);

 		if (error)
 			break;

 		sdp->sd_replayed_blocks++;
 	}

 	return error;
 }

 static void buf_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
 {
 	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
 	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

 	if (error) {
 		gfs2_meta_sync(ip->i_gl);
 		return;
 	}
 	if (pass != 1)
 		return;

 	gfs2_meta_sync(ip->i_gl);

 	fs_info(sdp, "jid=%u: Replayed %u of %u blocks\n",
 	        jd->jd_jid, sdp->sd_replayed_blocks, sdp->sd_found_blocks);
 }

 static void revoke_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
 {
 	struct gfs2_trans *tr;

 	tr = current->journal_info;
 	tr->tr_touched = 1;
 	tr->tr_num_revoke++;
 	sdp->sd_log_num_revoke++;
 	list_add(&le->le_list, &sdp->sd_log_le_revoke);
 }

 static void revoke_lo_before_commit(struct gfs2_sbd *sdp)
 {
 	struct gfs2_log_descriptor *ld;
 	struct gfs2_meta_header *mh;
 	struct buffer_head *bh;
 	unsigned int offset;
 	struct list_head *head = &sdp->sd_log_le_revoke;
 	struct gfs2_bufdata *bd;

 	if (!sdp->sd_log_num_revoke)
 		return;

 	bh = gfs2_get_log_desc(sdp, GFS2_LOG_DESC_REVOKE);
 	ld = bh_log_desc(bh);
 	ld->ld_length = cpu_to_be32(gfs2_struct2blk(sdp, sdp->sd_log_num_revoke,
 						    sizeof(u64)));
 	ld->ld_data1 = cpu_to_be32(sdp->sd_log_num_revoke);
 	offset = sizeof(struct gfs2_log_descriptor);

 	while (!list_empty(head)) {
 		bd = list_entry(head->next, struct gfs2_bufdata, bd_le.le_list);
 		list_del_init(&bd->bd_le.le_list);
 		sdp->sd_log_num_revoke--;

 		if (offset + sizeof(u64) > sdp->sd_sb.sb_bsize) {
 			submit_bh(WRITE_SYNC, bh);

 			bh = gfs2_log_get_buf(sdp);
 			mh = (struct gfs2_meta_header *)bh->b_data;
 			mh->mh_magic = cpu_to_be32(GFS2_MAGIC);
 			mh->mh_type = cpu_to_be32(GFS2_METATYPE_LB);
 			mh->mh_format = cpu_to_be32(GFS2_FORMAT_LB);
 			offset = sizeof(struct gfs2_meta_header);
 		}

 		*(__be64 *)(bh->b_data + offset) = cpu_to_be64(bd->bd_blkno);
 		kmem_cache_free(gfs2_bufdata_cachep, bd);

 		offset += sizeof(u64);
 	}
 	gfs2_assert_withdraw(sdp, !sdp->sd_log_num_revoke);

 	submit_bh(WRITE_SYNC, bh);
 }

 static void revoke_lo_before_scan(struct gfs2_jdesc *jd,
 				  struct gfs2_log_header_host *head, int pass)
 {
 	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

 	if (pass != 0)
 		return;

 	sdp->sd_found_revokes = 0;
 	sdp->sd_replay_tail = head->lh_tail;
 }

 static int revoke_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
 				   struct gfs2_log_descriptor *ld, __be64 *ptr,
 				   int pass)
 {
 	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 	unsigned int blks = be32_to_cpu(ld->ld_length);
 	unsigned int revokes = be32_to_cpu(ld->ld_data1);
 	struct buffer_head *bh;
 	unsigned int offset;
 	u64 blkno;
 	int first = 1;
 	int error;

 	if (pass != 0 || be32_to_cpu(ld->ld_type) != GFS2_LOG_DESC_REVOKE)
 		return 0;

 	offset = sizeof(struct gfs2_log_descriptor);

 	for (; blks; gfs2_replay_incr_blk(sdp, &start), blks--) {
 		error = gfs2_replay_read_block(jd, start, &bh);
 		if (error)
 			return error;

 		if (!first)
 			gfs2_metatype_check(sdp, bh, GFS2_METATYPE_LB);

 		while (offset + sizeof(u64) <= sdp->sd_sb.sb_bsize) {
 			blkno = be64_to_cpu(*(__be64 *)(bh->b_data + offset));

 			error = gfs2_revoke_add(sdp, blkno, start);
 			if (error < 0) {
 				brelse(bh);
 				return error;
 			}
 			else if (error)
 				sdp->sd_found_revokes++;

 			if (!--revokes)
 				break;
 			offset += sizeof(u64);
 		}

 		brelse(bh);
 		offset = sizeof(struct gfs2_meta_header);
 		first = 0;
 	}

 	return 0;
 }

 static void revoke_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
 {
 	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

 	if (error) {
 		gfs2_revoke_clean(sdp);
 		return;
 	}
 	if (pass != 1)
 		return;

 	fs_info(sdp, "jid=%u: Found %u revoke tags\n",
 	        jd->jd_jid, sdp->sd_found_revokes);

 	gfs2_revoke_clean(sdp);
 }

 static void rg_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
 {
 	struct gfs2_rgrpd *rgd;
 	struct gfs2_trans *tr = current->journal_info;

 	tr->tr_touched = 1;

 	rgd = container_of(le, struct gfs2_rgrpd, rd_le);

 	gfs2_log_lock(sdp);
 	if (!list_empty(&le->le_list)){
 		gfs2_log_unlock(sdp);
 		return;
 	}
 	gfs2_rgrp_bh_hold(rgd);
 	sdp->sd_log_num_rg++;
 	list_add(&le->le_list, &sdp->sd_log_le_rg);
 	gfs2_log_unlock(sdp);
 }

 static void rg_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
 {
 	struct list_head *head = &sdp->sd_log_le_rg;
 	struct gfs2_rgrpd *rgd;

 	while (!list_empty(head)) {
 		rgd = list_entry(head->next, struct gfs2_rgrpd, rd_le.le_list);
 		list_del_init(&rgd->rd_le.le_list);
 		sdp->sd_log_num_rg--;

 		gfs2_rgrp_repolish_clones(rgd);
 		gfs2_rgrp_bh_put(rgd);
 	}
 	gfs2_assert_warn(sdp, !sdp->sd_log_num_rg);
 }

 /**
  * databuf_lo_add - Add a databuf to the transaction.
  *
  * This is used in two distinct cases:
  * i) In ordered write mode
  *    We put the data buffer on a list so that we can ensure that its
  *    synced to disk at the right time
  * ii) In journaled data mode
  *    We need to journal the data block in the same way as metadata in
  *    the functions above. The difference is that here we have a tag
  *    which is two __be64's being the block number (as per meta data)
  *    and a flag which says whether the data block needs escaping or
  *    not. This means we need a new log entry for each 251 or so data
  *    blocks, which isn't an enormous overhead but twice as much as
  *    for normal metadata blocks.
  */
 static void databuf_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
 {
 	struct gfs2_bufdata *bd = container_of(le, struct gfs2_bufdata, bd_le);
 	struct gfs2_trans *tr = current->journal_info;
 	struct address_space *mapping = bd->bd_bh->b_page->mapping;
 	struct gfs2_inode *ip = GFS2_I(mapping->host);

 	lock_buffer(bd->bd_bh);
 	gfs2_log_lock(sdp);
 	if (tr) {
 		if (!list_empty(&bd->bd_list_tr))
 			goto out;
 		tr->tr_touched = 1;
 		if (gfs2_is_jdata(ip)) {
 			tr->tr_num_buf++;
 			list_add(&bd->bd_list_tr, &tr->tr_list_buf);
 		}
 	}
 	if (!list_empty(&le->le_list))
 		goto out;

 	set_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
 	set_bit(GLF_DIRTY, &bd->bd_gl->gl_flags);
 	if (gfs2_is_jdata(ip)) {
 		gfs2_pin(sdp, bd->bd_bh);
 		tr->tr_num_databuf_new++;
 		sdp->sd_log_num_databuf++;
 		list_add_tail(&le->le_list, &sdp->sd_log_le_databuf);
 	} else {
 		list_add_tail(&le->le_list, &sdp->sd_log_le_ordered);
 	}
 out:
 	gfs2_log_unlock(sdp);
 	unlock_buffer(bd->bd_bh);
 }

 static void gfs2_check_magic(struct buffer_head *bh)
 {
 	void *kaddr;
 	__be32 *ptr;

 	clear_buffer_escaped(bh);
 	kaddr = kmap_atomic(bh->b_page, KM_USER0);
 	ptr = kaddr + bh_offset(bh);
 	if (*ptr == cpu_to_be32(GFS2_MAGIC))
 		set_buffer_escaped(bh);
 	kunmap_atomic(kaddr, KM_USER0);
 }

 static void gfs2_write_blocks(struct gfs2_sbd *sdp, struct buffer_head *bh,
 			      struct list_head *list, struct list_head *done,
 			      unsigned int n)
 {
 	struct buffer_head *bh1;
 	struct gfs2_log_descriptor *ld;
 	struct gfs2_bufdata *bd;
 	__be64 *ptr;

 	if (!bh)
 		return;

 	ld = bh_log_desc(bh);
 	ld->ld_length = cpu_to_be32(n + 1);
 	ld->ld_data1 = cpu_to_be32(n);

 	ptr = bh_log_ptr(bh);

 	get_bh(bh);
 	submit_bh(WRITE_SYNC, bh);
 	gfs2_log_lock(sdp);
 	while(!list_empty(list)) {
 		bd = list_entry(list->next, struct gfs2_bufdata, bd_le.le_list);
 		list_move_tail(&bd->bd_le.le_list, done);
 		get_bh(bd->bd_bh);
 		while (be64_to_cpu(*ptr) != bd->bd_bh->b_blocknr) {
 			gfs2_log_incr_head(sdp);
 			ptr += 2;
 		}
 		gfs2_log_unlock(sdp);
 		lock_buffer(bd->bd_bh);
 		if (buffer_escaped(bd->bd_bh)) {
 			void *kaddr;
 			bh1 = gfs2_log_get_buf(sdp);
 			kaddr = kmap_atomic(bd->bd_bh->b_page, KM_USER0);
 			memcpy(bh1->b_data, kaddr + bh_offset(bd->bd_bh),
 			       bh1->b_size);
 			kunmap_atomic(kaddr, KM_USER0);
 			*(__be32 *)bh1->b_data = 0;
 			clear_buffer_escaped(bd->bd_bh);
 			unlock_buffer(bd->bd_bh);
 			brelse(bd->bd_bh);
 		} else {
 			bh1 = gfs2_log_fake_buf(sdp, bd->bd_bh);
 		}
 		submit_bh(WRITE_SYNC, bh1);
 		gfs2_log_lock(sdp);
 		ptr += 2;
 	}
 	gfs2_log_unlock(sdp);
 	brelse(bh);
 }

 /**
  * databuf_lo_before_commit - Scan the data buffers, writing as we go
  *
  */

 static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
 {
 	struct gfs2_bufdata *bd = NULL;
 	struct buffer_head *bh = NULL;
 	unsigned int n = 0;
 	__be64 *ptr = NULL, *end = NULL;
 	LIST_HEAD(processed);
 	LIST_HEAD(in_progress);

 	gfs2_log_lock(sdp);
 	while (!list_empty(&sdp->sd_log_le_databuf)) {
 		if (ptr == end) {
 			gfs2_log_unlock(sdp);
 			gfs2_write_blocks(sdp, bh, &in_progress, &processed, n);
 			n = 0;
 			bh = gfs2_get_log_desc(sdp, GFS2_LOG_DESC_JDATA);
 			ptr = bh_log_ptr(bh);
 			end = bh_ptr_end(bh) - 1;
 			gfs2_log_lock(sdp);
 			continue;
 		}
 		bd = list_entry(sdp->sd_log_le_databuf.next, struct gfs2_bufdata, bd_le.le_list);
 		list_move_tail(&bd->bd_le.le_list, &in_progress);
 		gfs2_check_magic(bd->bd_bh);
 		*ptr++ = cpu_to_be64(bd->bd_bh->b_blocknr);
 		*ptr++ = cpu_to_be64(buffer_escaped(bh) ? 1 : 0);
 		n++;
 	}
 	gfs2_log_unlock(sdp);
 	gfs2_write_blocks(sdp, bh, &in_progress, &processed, n);
 	gfs2_log_lock(sdp);
 	list_splice(&processed, &sdp->sd_log_le_databuf);
 	gfs2_log_unlock(sdp);
 }

 static int databuf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
 				    struct gfs2_log_descriptor *ld,
 				    __be64 *ptr, int pass)
 {
 	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
 	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 	struct gfs2_glock *gl = ip->i_gl;
 	unsigned int blks = be32_to_cpu(ld->ld_data1);
 	struct buffer_head *bh_log, *bh_ip;
 	u64 blkno;
 	u64 esc;
 	int error = 0;

 	if (pass != 1 || be32_to_cpu(ld->ld_type) != GFS2_LOG_DESC_JDATA)
 		return 0;

 	gfs2_replay_incr_blk(sdp, &start);
 	for (; blks; gfs2_replay_incr_blk(sdp, &start), blks--) {
 		blkno = be64_to_cpu(*ptr++);
 		esc = be64_to_cpu(*ptr++);

 		sdp->sd_found_blocks++;

 		if (gfs2_revoke_check(sdp, blkno, start))
 			continue;

 		error = gfs2_replay_read_block(jd, start, &bh_log);
 		if (error)
 			return error;

 		bh_ip = gfs2_meta_new(gl, blkno);
 		memcpy(bh_ip->b_data, bh_log->b_data, bh_log->b_size);

 		/* Unescape */
 		if (esc) {
 			__be32 *eptr = (__be32 *)bh_ip->b_data;
 			*eptr = cpu_to_be32(GFS2_MAGIC);
 		}
 		mark_buffer_dirty(bh_ip);

 		brelse(bh_log);
 		brelse(bh_ip);
 		if (error)
 			break;

 		sdp->sd_replayed_blocks++;
 	}

 	return error;
 }

 /* FIXME: sort out accounting for log blocks etc. */

 static void databuf_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
 {
 	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
 	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

 	if (error) {
 		gfs2_meta_sync(ip->i_gl);
 		return;
 	}
 	if (pass != 1)
 		return;

 	/* data sync? */
 	gfs2_meta_sync(ip->i_gl);

 	fs_info(sdp, "jid=%u: Replayed %u of %u data blocks\n",
 		jd->jd_jid, sdp->sd_replayed_blocks, sdp->sd_found_blocks);
 }

 static void databuf_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
 {
 	struct list_head *head = &sdp->sd_log_le_databuf;
 	struct gfs2_bufdata *bd;

 	while (!list_empty(head)) {
 		bd = list_entry(head->next, struct gfs2_bufdata, bd_le.le_list);
 		list_del_init(&bd->bd_le.le_list);
 		sdp->sd_log_num_databuf--;
 		gfs2_unpin(sdp, bd->bd_bh, ai);
 	}
 	gfs2_assert_warn(sdp, !sdp->sd_log_num_databuf);
 }


 const struct gfs2_log_operations gfs2_buf_lops = {
 	.lo_add = buf_lo_add,
 	.lo_before_commit = buf_lo_before_commit,
 	.lo_after_commit = buf_lo_after_commit,
 	.lo_before_scan = buf_lo_before_scan,
 	.lo_scan_elements = buf_lo_scan_elements,
 	.lo_after_scan = buf_lo_after_scan,
 	.lo_name = "buf",
 };

 const struct gfs2_log_operations gfs2_revoke_lops = {
 	.lo_add = revoke_lo_add,
 	.lo_before_commit = revoke_lo_before_commit,
 	.lo_before_scan = revoke_lo_before_scan,
 	.lo_scan_elements = revoke_lo_scan_elements,
 	.lo_after_scan = revoke_lo_after_scan,
 	.lo_name = "revoke",
 };

 const struct gfs2_log_operations gfs2_rg_lops = {
 	.lo_add = rg_lo_add,
 	.lo_after_commit = rg_lo_after_commit,
 	.lo_name = "rg",
 };

 const struct gfs2_log_operations gfs2_databuf_lops = {
 	.lo_add = databuf_lo_add,
 	.lo_before_commit = databuf_lo_before_commit,
 	.lo_after_commit = databuf_lo_after_commit,
 	.lo_scan_elements = databuf_lo_scan_elements,
 	.lo_after_scan = databuf_lo_after_scan,
 	.lo_name = "databuf",
 };

 const struct gfs2_log_operations *gfs2_log_ops[] = {
 	&gfs2_databuf_lops,
 	&gfs2_buf_lops,
 	&gfs2_rg_lops,
 	&gfs2_revoke_lops,
 	NULL,
 };
	/*
	* 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/sched.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/bio.h>
	#include <linux/fs.h>

	#include "gfs2.h"
	#include "incore.h"
	#include "inode.h"
	#include "glock.h"
	#include "log.h"
	#include "lops.h"
	#include "meta_io.h"
	#include "recovery.h"
	#include "rgrp.h"
	#include "trans.h"
	#include "util.h"
	#include "trace_gfs2.h"

	/**
	* gfs2_pin - Pin a buffer in memory
	* @sdp: The superblock
	* @bh: The buffer to be pinned
	*
	* The log lock must be held when calling this function
	*/
	static void gfs2_pin(struct gfs2_sbd sdp, struct buffer_head bh)
	{
	struct gfs2_bufdata *bd;

	gfs2_assert_withdraw(sdp, test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags));

	clear_buffer_dirty(bh);
	if (test_set_buffer_pinned(bh))
	gfs2_assert_withdraw(sdp, 0);
	if (!buffer_uptodate(bh))
	gfs2_io_error_bh(sdp, bh);
	bd = bh->b_private;
	/* If this buffer is in the AIL and it has already been written
	* to in-place disk block, remove it from the AIL.
	*/
	spin_lock(&sdp->sd_ail_lock);
	if (bd->bd_ail)
	list_move(&bd->bd_ail_st_list, &bd->bd_ail->ai_ail2_list);
	spin_unlock(&sdp->sd_ail_lock);
	get_bh(bh);
	atomic_inc(&sdp->sd_log_pinned);
	trace_gfs2_pin(bd, 1);
	}

	/**
	* gfs2_unpin - Unpin a buffer
	* @sdp: the filesystem the buffer belongs to
	* @bh: The buffer to unpin
	* @ai:
	*
	*/

	static void gfs2_unpin(struct gfs2_sbd sdp, struct buffer_head bh,
	struct gfs2_ail *ai)
	{
	struct gfs2_bufdata *bd = bh->b_private;

	gfs2_assert_withdraw(sdp, buffer_uptodate(bh));

	if (!buffer_pinned(bh))
	gfs2_assert_withdraw(sdp, 0);

	lock_buffer(bh);
	mark_buffer_dirty(bh);
	clear_buffer_pinned(bh);

	spin_lock(&sdp->sd_ail_lock);
	if (bd->bd_ail) {
	list_del(&bd->bd_ail_st_list);
	brelse(bh);
	} else {
	struct gfs2_glock *gl = bd->bd_gl;
	list_add(&bd->bd_ail_gl_list, &gl->gl_ail_list);
	atomic_inc(&gl->gl_ail_count);
	}
	bd->bd_ail = ai;
	list_add(&bd->bd_ail_st_list, &ai->ai_ail1_list);
	spin_unlock(&sdp->sd_ail_lock);

	if (test_and_clear_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags))
	gfs2_glock_schedule_for_reclaim(bd->bd_gl);
	trace_gfs2_pin(bd, 0);
	unlock_buffer(bh);
	atomic_dec(&sdp->sd_log_pinned);
	}


	static inline struct gfs2_log_descriptor bh_log_desc(struct buffer_head bh)
	{
	return (struct gfs2_log_descriptor *)bh->b_data;
	}

	static inline __be64 bh_log_ptr(struct buffer_head bh)
	{
	struct gfs2_log_descriptor *ld = bh_log_desc(bh);
	return (__force __be64 *)(ld + 1);
	}

	static inline __be64 bh_ptr_end(struct buffer_head bh)
	{
	return (__force __be64 *)(bh->b_data + bh->b_size);
	}


	static struct buffer_head gfs2_get_log_desc(struct gfs2_sbd sdp, u32 ld_type)
	{
	struct buffer_head *bh = gfs2_log_get_buf(sdp);
	struct gfs2_log_descriptor *ld = bh_log_desc(bh);
	ld->ld_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
	ld->ld_header.mh_type = cpu_to_be32(GFS2_METATYPE_LD);
	ld->ld_header.mh_format = cpu_to_be32(GFS2_FORMAT_LD);
	ld->ld_type = cpu_to_be32(ld_type);
	ld->ld_length = 0;
	ld->ld_data1 = 0;
	ld->ld_data2 = 0;
	memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));
	return bh;
	}

	static void buf_lo_add(struct gfs2_sbd sdp, struct gfs2_log_element le)
	{
	struct gfs2_bufdata *bd = container_of(le, struct gfs2_bufdata, bd_le);
	struct gfs2_meta_header *mh;
	struct gfs2_trans *tr;

	lock_buffer(bd->bd_bh);
	gfs2_log_lock(sdp);
	if (!list_empty(&bd->bd_list_tr))
	goto out;
	tr = current->journal_info;
	tr->tr_touched = 1;
	tr->tr_num_buf++;
	list_add(&bd->bd_list_tr, &tr->tr_list_buf);
	if (!list_empty(&le->le_list))
	goto out;
	set_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
	set_bit(GLF_DIRTY, &bd->bd_gl->gl_flags);
	gfs2_meta_check(sdp, bd->bd_bh);
	gfs2_pin(sdp, bd->bd_bh);
	mh = (struct gfs2_meta_header *)bd->bd_bh->b_data;
	mh->__pad0 = cpu_to_be64(0);
	mh->mh_jid = cpu_to_be32(sdp->sd_jdesc->jd_jid);
	sdp->sd_log_num_buf++;
	list_add(&le->le_list, &sdp->sd_log_le_buf);
	tr->tr_num_buf_new++;
	out:
	gfs2_log_unlock(sdp);
	unlock_buffer(bd->bd_bh);
	}

	static void buf_lo_before_commit(struct gfs2_sbd *sdp)
	{
	struct buffer_head *bh;
	struct gfs2_log_descriptor *ld;
	struct gfs2_bufdata bd1 = NULL, bd2;
	unsigned int total;
	unsigned int limit;
	unsigned int num;
	unsigned n;
	__be64 *ptr;

	limit = buf_limit(sdp);
	/* for 4k blocks, limit = 503 */

	gfs2_log_lock(sdp);
	total = sdp->sd_log_num_buf;
	bd1 = bd2 = list_prepare_entry(bd1, &sdp->sd_log_le_buf, bd_le.le_list);
	while(total) {
	num = total;
	if (total > limit)
	num = limit;
	gfs2_log_unlock(sdp);
	bh = gfs2_get_log_desc(sdp, GFS2_LOG_DESC_METADATA);
	gfs2_log_lock(sdp);
	ld = bh_log_desc(bh);
	ptr = bh_log_ptr(bh);
	ld->ld_length = cpu_to_be32(num + 1);
	ld->ld_data1 = cpu_to_be32(num);

	n = 0;
	list_for_each_entry_continue(bd1, &sdp->sd_log_le_buf,
	bd_le.le_list) {
	*ptr++ = cpu_to_be64(bd1->bd_bh->b_blocknr);
	if (++n >= num)
	break;
	}

	gfs2_log_unlock(sdp);
	submit_bh(WRITE_SYNC, bh);
	gfs2_log_lock(sdp);

	n = 0;
	list_for_each_entry_continue(bd2, &sdp->sd_log_le_buf,
	bd_le.le_list) {
	get_bh(bd2->bd_bh);
	gfs2_log_unlock(sdp);
	lock_buffer(bd2->bd_bh);
	bh = gfs2_log_fake_buf(sdp, bd2->bd_bh);
	submit_bh(WRITE_SYNC, bh);
	gfs2_log_lock(sdp);
	if (++n >= num)
	break;
	}

	BUG_ON(total < num);
	total -= num;
	}
	gfs2_log_unlock(sdp);
	}

	static void buf_lo_after_commit(struct gfs2_sbd sdp, struct gfs2_ail ai)
	{
	struct list_head *head = &sdp->sd_log_le_buf;
	struct gfs2_bufdata *bd;

	while (!list_empty(head)) {
	bd = list_entry(head->next, struct gfs2_bufdata, bd_le.le_list);
	list_del_init(&bd->bd_le.le_list);
	sdp->sd_log_num_buf--;

	gfs2_unpin(sdp, bd->bd_bh, ai);
	}
	gfs2_assert_warn(sdp, !sdp->sd_log_num_buf);
	}

	static void buf_lo_before_scan(struct gfs2_jdesc *jd,
	struct gfs2_log_header_host *head, int pass)
	{
	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

	if (pass != 0)
	return;

	sdp->sd_found_blocks = 0;
	sdp->sd_replayed_blocks = 0;
	}

	static int buf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
	struct gfs2_log_descriptor ld, __be64 ptr,
	int pass)
	{
	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
	struct gfs2_glock *gl = ip->i_gl;
	unsigned int blks = be32_to_cpu(ld->ld_data1);
	struct buffer_head bh_log, bh_ip;
	u64 blkno;
	int error = 0;

	if (pass != 1 \|\| be32_to_cpu(ld->ld_type) != GFS2_LOG_DESC_METADATA)
	return 0;

	gfs2_replay_incr_blk(sdp, &start);

	for (; blks; gfs2_replay_incr_blk(sdp, &start), blks--) {
	blkno = be64_to_cpu(*ptr++);

	sdp->sd_found_blocks++;

	if (gfs2_revoke_check(sdp, blkno, start))
	continue;

	error = gfs2_replay_read_block(jd, start, &bh_log);
	if (error)
	return error;

	bh_ip = gfs2_meta_new(gl, blkno);
	memcpy(bh_ip->b_data, bh_log->b_data, bh_log->b_size);

	if (gfs2_meta_check(sdp, bh_ip))
	error = -EIO;
	else
	mark_buffer_dirty(bh_ip);

	brelse(bh_log);
	brelse(bh_ip);

	if (error)
	break;

	sdp->sd_replayed_blocks++;
	}

	return error;
	}

	static void buf_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
	{
	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

	if (error) {
	gfs2_meta_sync(ip->i_gl);
	return;
	}
	if (pass != 1)
	return;

	gfs2_meta_sync(ip->i_gl);

	fs_info(sdp, "jid=%u: Replayed %u of %u blocks\n",
	jd->jd_jid, sdp->sd_replayed_blocks, sdp->sd_found_blocks);
	}

	static void revoke_lo_add(struct gfs2_sbd sdp, struct gfs2_log_element le)
	{
	struct gfs2_trans *tr;

	tr = current->journal_info;
	tr->tr_touched = 1;
	tr->tr_num_revoke++;
	sdp->sd_log_num_revoke++;
	list_add(&le->le_list, &sdp->sd_log_le_revoke);
	}

	static void revoke_lo_before_commit(struct gfs2_sbd *sdp)
	{
	struct gfs2_log_descriptor *ld;
	struct gfs2_meta_header *mh;
	struct buffer_head *bh;
	unsigned int offset;
	struct list_head *head = &sdp->sd_log_le_revoke;
	struct gfs2_bufdata *bd;

	if (!sdp->sd_log_num_revoke)
	return;

	bh = gfs2_get_log_desc(sdp, GFS2_LOG_DESC_REVOKE);
	ld = bh_log_desc(bh);
	ld->ld_length = cpu_to_be32(gfs2_struct2blk(sdp, sdp->sd_log_num_revoke,
	sizeof(u64)));
	ld->ld_data1 = cpu_to_be32(sdp->sd_log_num_revoke);
	offset = sizeof(struct gfs2_log_descriptor);

	while (!list_empty(head)) {
	bd = list_entry(head->next, struct gfs2_bufdata, bd_le.le_list);
	list_del_init(&bd->bd_le.le_list);
	sdp->sd_log_num_revoke--;

	if (offset + sizeof(u64) > sdp->sd_sb.sb_bsize) {
	submit_bh(WRITE_SYNC, bh);

	bh = gfs2_log_get_buf(sdp);
	mh = (struct gfs2_meta_header *)bh->b_data;
	mh->mh_magic = cpu_to_be32(GFS2_MAGIC);
	mh->mh_type = cpu_to_be32(GFS2_METATYPE_LB);
	mh->mh_format = cpu_to_be32(GFS2_FORMAT_LB);
	offset = sizeof(struct gfs2_meta_header);
	}

	(__be64 )(bh->b_data + offset) = cpu_to_be64(bd->bd_blkno);
	kmem_cache_free(gfs2_bufdata_cachep, bd);

	offset += sizeof(u64);
	}
	gfs2_assert_withdraw(sdp, !sdp->sd_log_num_revoke);

	submit_bh(WRITE_SYNC, bh);
	}

	static void revoke_lo_before_scan(struct gfs2_jdesc *jd,
	struct gfs2_log_header_host *head, int pass)
	{
	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

	if (pass != 0)
	return;

	sdp->sd_found_revokes = 0;
	sdp->sd_replay_tail = head->lh_tail;
	}

	static int revoke_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
	struct gfs2_log_descriptor ld, __be64 ptr,
	int pass)
	{
	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
	unsigned int blks = be32_to_cpu(ld->ld_length);
	unsigned int revokes = be32_to_cpu(ld->ld_data1);
	struct buffer_head *bh;
	unsigned int offset;
	u64 blkno;
	int first = 1;
	int error;

	if (pass != 0 \|\| be32_to_cpu(ld->ld_type) != GFS2_LOG_DESC_REVOKE)
	return 0;

	offset = sizeof(struct gfs2_log_descriptor);

	for (; blks; gfs2_replay_incr_blk(sdp, &start), blks--) {
	error = gfs2_replay_read_block(jd, start, &bh);
	if (error)
	return error;

	if (!first)
	gfs2_metatype_check(sdp, bh, GFS2_METATYPE_LB);

	while (offset + sizeof(u64) <= sdp->sd_sb.sb_bsize) {
	blkno = be64_to_cpu((__be64 )(bh->b_data + offset));

	error = gfs2_revoke_add(sdp, blkno, start);
	if (error < 0) {
	brelse(bh);
	return error;
	}
	else if (error)
	sdp->sd_found_revokes++;

	if (!--revokes)
	break;
	offset += sizeof(u64);
	}

	brelse(bh);
	offset = sizeof(struct gfs2_meta_header);
	first = 0;
	}

	return 0;
	}

	static void revoke_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
	{
	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

	if (error) {
	gfs2_revoke_clean(sdp);
	return;
	}
	if (pass != 1)
	return;

	fs_info(sdp, "jid=%u: Found %u revoke tags\n",
	jd->jd_jid, sdp->sd_found_revokes);

	gfs2_revoke_clean(sdp);
	}

	static void rg_lo_add(struct gfs2_sbd sdp, struct gfs2_log_element le)
	{
	struct gfs2_rgrpd *rgd;
	struct gfs2_trans *tr = current->journal_info;

	tr->tr_touched = 1;

	rgd = container_of(le, struct gfs2_rgrpd, rd_le);

	gfs2_log_lock(sdp);
	if (!list_empty(&le->le_list)){
	gfs2_log_unlock(sdp);
	return;
	}
	gfs2_rgrp_bh_hold(rgd);
	sdp->sd_log_num_rg++;
	list_add(&le->le_list, &sdp->sd_log_le_rg);
	gfs2_log_unlock(sdp);
	}

	static void rg_lo_after_commit(struct gfs2_sbd sdp, struct gfs2_ail ai)
	{
	struct list_head *head = &sdp->sd_log_le_rg;
	struct gfs2_rgrpd *rgd;

	while (!list_empty(head)) {
	rgd = list_entry(head->next, struct gfs2_rgrpd, rd_le.le_list);
	list_del_init(&rgd->rd_le.le_list);
	sdp->sd_log_num_rg--;

	gfs2_rgrp_repolish_clones(rgd);
	gfs2_rgrp_bh_put(rgd);
	}
	gfs2_assert_warn(sdp, !sdp->sd_log_num_rg);
	}

	/**
	* databuf_lo_add - Add a databuf to the transaction.
	*
	* This is used in two distinct cases:
	* i) In ordered write mode
	* We put the data buffer on a list so that we can ensure that its
	* synced to disk at the right time
	* ii) In journaled data mode
	* We need to journal the data block in the same way as metadata in
	* the functions above. The difference is that here we have a tag
	* which is two __be64's being the block number (as per meta data)
	* and a flag which says whether the data block needs escaping or
	* not. This means we need a new log entry for each 251 or so data
	* blocks, which isn't an enormous overhead but twice as much as
	* for normal metadata blocks.
	*/
	static void databuf_lo_add(struct gfs2_sbd sdp, struct gfs2_log_element le)
	{
	struct gfs2_bufdata *bd = container_of(le, struct gfs2_bufdata, bd_le);
	struct gfs2_trans *tr = current->journal_info;
	struct address_space *mapping = bd->bd_bh->b_page->mapping;
	struct gfs2_inode *ip = GFS2_I(mapping->host);

	lock_buffer(bd->bd_bh);
	gfs2_log_lock(sdp);
	if (tr) {
	if (!list_empty(&bd->bd_list_tr))
	goto out;
	tr->tr_touched = 1;
	if (gfs2_is_jdata(ip)) {
	tr->tr_num_buf++;
	list_add(&bd->bd_list_tr, &tr->tr_list_buf);
	}
	}
	if (!list_empty(&le->le_list))
	goto out;

	set_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
	set_bit(GLF_DIRTY, &bd->bd_gl->gl_flags);
	if (gfs2_is_jdata(ip)) {
	gfs2_pin(sdp, bd->bd_bh);
	tr->tr_num_databuf_new++;
	sdp->sd_log_num_databuf++;
	list_add_tail(&le->le_list, &sdp->sd_log_le_databuf);
	} else {
	list_add_tail(&le->le_list, &sdp->sd_log_le_ordered);
	}
	out:
	gfs2_log_unlock(sdp);
	unlock_buffer(bd->bd_bh);
	}

	static void gfs2_check_magic(struct buffer_head *bh)
	{
	void *kaddr;
	__be32 *ptr;

	clear_buffer_escaped(bh);
	kaddr = kmap_atomic(bh->b_page, KM_USER0);
	ptr = kaddr + bh_offset(bh);
	if (*ptr == cpu_to_be32(GFS2_MAGIC))
	set_buffer_escaped(bh);
	kunmap_atomic(kaddr, KM_USER0);
	}

	static void gfs2_write_blocks(struct gfs2_sbd sdp, struct buffer_head bh,
	struct list_head list, struct list_head done,
	unsigned int n)
	{
	struct buffer_head *bh1;
	struct gfs2_log_descriptor *ld;
	struct gfs2_bufdata *bd;
	__be64 *ptr;

	if (!bh)
	return;

	ld = bh_log_desc(bh);
	ld->ld_length = cpu_to_be32(n + 1);
	ld->ld_data1 = cpu_to_be32(n);

	ptr = bh_log_ptr(bh);

	get_bh(bh);
	submit_bh(WRITE_SYNC, bh);
	gfs2_log_lock(sdp);
	while(!list_empty(list)) {
	bd = list_entry(list->next, struct gfs2_bufdata, bd_le.le_list);
	list_move_tail(&bd->bd_le.le_list, done);
	get_bh(bd->bd_bh);
	while (be64_to_cpu(*ptr) != bd->bd_bh->b_blocknr) {
	gfs2_log_incr_head(sdp);
	ptr += 2;
	}
	gfs2_log_unlock(sdp);
	lock_buffer(bd->bd_bh);
	if (buffer_escaped(bd->bd_bh)) {
	void *kaddr;
	bh1 = gfs2_log_get_buf(sdp);
	kaddr = kmap_atomic(bd->bd_bh->b_page, KM_USER0);
	memcpy(bh1->b_data, kaddr + bh_offset(bd->bd_bh),
	bh1->b_size);
	kunmap_atomic(kaddr, KM_USER0);
	(__be32 )bh1->b_data = 0;
	clear_buffer_escaped(bd->bd_bh);
	unlock_buffer(bd->bd_bh);
	brelse(bd->bd_bh);
	} else {
	bh1 = gfs2_log_fake_buf(sdp, bd->bd_bh);
	}
	submit_bh(WRITE_SYNC, bh1);
	gfs2_log_lock(sdp);
	ptr += 2;
	}
	gfs2_log_unlock(sdp);
	brelse(bh);
	}

	/**
	* databuf_lo_before_commit - Scan the data buffers, writing as we go
	*
	*/

	static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
	{
	struct gfs2_bufdata *bd = NULL;
	struct buffer_head *bh = NULL;
	unsigned int n = 0;
	__be64 ptr = NULL, end = NULL;
	LIST_HEAD(processed);
	LIST_HEAD(in_progress);

	gfs2_log_lock(sdp);
	while (!list_empty(&sdp->sd_log_le_databuf)) {
	if (ptr == end) {
	gfs2_log_unlock(sdp);
	gfs2_write_blocks(sdp, bh, &in_progress, &processed, n);
	n = 0;
	bh = gfs2_get_log_desc(sdp, GFS2_LOG_DESC_JDATA);
	ptr = bh_log_ptr(bh);
	end = bh_ptr_end(bh) - 1;
	gfs2_log_lock(sdp);
	continue;
	}
	bd = list_entry(sdp->sd_log_le_databuf.next, struct gfs2_bufdata, bd_le.le_list);
	list_move_tail(&bd->bd_le.le_list, &in_progress);
	gfs2_check_magic(bd->bd_bh);
	*ptr++ = cpu_to_be64(bd->bd_bh->b_blocknr);
	*ptr++ = cpu_to_be64(buffer_escaped(bh) ? 1 : 0);
	n++;
	}
	gfs2_log_unlock(sdp);
	gfs2_write_blocks(sdp, bh, &in_progress, &processed, n);
	gfs2_log_lock(sdp);
	list_splice(&processed, &sdp->sd_log_le_databuf);
	gfs2_log_unlock(sdp);
	}

	static int databuf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
	struct gfs2_log_descriptor *ld,
	__be64 *ptr, int pass)
	{
	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
	struct gfs2_glock *gl = ip->i_gl;
	unsigned int blks = be32_to_cpu(ld->ld_data1);
	struct buffer_head bh_log, bh_ip;
	u64 blkno;
	u64 esc;
	int error = 0;

	if (pass != 1 \|\| be32_to_cpu(ld->ld_type) != GFS2_LOG_DESC_JDATA)
	return 0;

	gfs2_replay_incr_blk(sdp, &start);
	for (; blks; gfs2_replay_incr_blk(sdp, &start), blks--) {
	blkno = be64_to_cpu(*ptr++);
	esc = be64_to_cpu(*ptr++);

	sdp->sd_found_blocks++;

	if (gfs2_revoke_check(sdp, blkno, start))
	continue;

	error = gfs2_replay_read_block(jd, start, &bh_log);
	if (error)
	return error;

	bh_ip = gfs2_meta_new(gl, blkno);
	memcpy(bh_ip->b_data, bh_log->b_data, bh_log->b_size);

	/* Unescape */
	if (esc) {
	__be32 eptr = (__be32 )bh_ip->b_data;
	*eptr = cpu_to_be32(GFS2_MAGIC);
	}
	mark_buffer_dirty(bh_ip);

	brelse(bh_log);
	brelse(bh_ip);
	if (error)
	break;

	sdp->sd_replayed_blocks++;
	}

	return error;
	}

	/* FIXME: sort out accounting for log blocks etc. */

	static void databuf_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
	{
	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

	if (error) {
	gfs2_meta_sync(ip->i_gl);
	return;
	}
	if (pass != 1)
	return;

	/* data sync? */
	gfs2_meta_sync(ip->i_gl);

	fs_info(sdp, "jid=%u: Replayed %u of %u data blocks\n",
	jd->jd_jid, sdp->sd_replayed_blocks, sdp->sd_found_blocks);
	}

	static void databuf_lo_after_commit(struct gfs2_sbd sdp, struct gfs2_ail ai)
	{
	struct list_head *head = &sdp->sd_log_le_databuf;
	struct gfs2_bufdata *bd;

	while (!list_empty(head)) {
	bd = list_entry(head->next, struct gfs2_bufdata, bd_le.le_list);
	list_del_init(&bd->bd_le.le_list);
	sdp->sd_log_num_databuf--;
	gfs2_unpin(sdp, bd->bd_bh, ai);
	}
	gfs2_assert_warn(sdp, !sdp->sd_log_num_databuf);
	}


	const struct gfs2_log_operations gfs2_buf_lops = {
	.lo_add = buf_lo_add,
	.lo_before_commit = buf_lo_before_commit,
	.lo_after_commit = buf_lo_after_commit,
	.lo_before_scan = buf_lo_before_scan,
	.lo_scan_elements = buf_lo_scan_elements,
	.lo_after_scan = buf_lo_after_scan,
	.lo_name = "buf",
	};

	const struct gfs2_log_operations gfs2_revoke_lops = {
	.lo_add = revoke_lo_add,
	.lo_before_commit = revoke_lo_before_commit,
	.lo_before_scan = revoke_lo_before_scan,
	.lo_scan_elements = revoke_lo_scan_elements,
	.lo_after_scan = revoke_lo_after_scan,
	.lo_name = "revoke",
	};

	const struct gfs2_log_operations gfs2_rg_lops = {
	.lo_add = rg_lo_add,
	.lo_after_commit = rg_lo_after_commit,
	.lo_name = "rg",
	};

	const struct gfs2_log_operations gfs2_databuf_lops = {
	.lo_add = databuf_lo_add,
	.lo_before_commit = databuf_lo_before_commit,
	.lo_after_commit = databuf_lo_after_commit,
	.lo_scan_elements = databuf_lo_scan_elements,
	.lo_after_scan = databuf_lo_after_scan,
	.lo_name = "databuf",
	};

	const struct gfs2_log_operations *gfs2_log_ops[] = {
	&gfs2_databuf_lops,
	&gfs2_buf_lops,
	&gfs2_rg_lops,
	&gfs2_revoke_lops,
	NULL,
	};