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/lm_interface.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"

 static void glock_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
 {
 	struct gfs2_glock *gl;
 	struct gfs2_trans *tr = current->journal_info;

 	tr->tr_touched = 1;

 	gl = container_of(le, struct gfs2_glock, gl_le);
 	if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(gl)))
 		return;

 	gfs2_log_lock(sdp);
 	if (!list_empty(&le->le_list)){
 		gfs2_log_unlock(sdp);
 		return;
 	}
 	gfs2_glock_hold(gl);
 	set_bit(GLF_DIRTY, &gl->gl_flags);
 	sdp->sd_log_num_gl++;
 	list_add(&le->le_list, &sdp->sd_log_le_gl);
 	gfs2_log_unlock(sdp);
 }

 static void glock_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
 {
 	struct list_head *head = &sdp->sd_log_le_gl;
 	struct gfs2_glock *gl;

 	while (!list_empty(head)) {
 		gl = list_entry(head->next, struct gfs2_glock, gl_le.le_list);
 		list_del_init(&gl->gl_le.le_list);
 		sdp->sd_log_num_gl--;

 		gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(gl));
 		gfs2_glock_put(gl);
 	}
 	gfs2_assert_warn(sdp, !sdp->sd_log_num_gl);
 }

 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_trans *tr;

 	gfs2_log_lock(sdp);
 	if (!list_empty(&bd->bd_list_tr)) {
 		gfs2_log_unlock(sdp);
 		return;
 	}
 	tr = current->journal_info;
 	tr->tr_touched = 1;
 	tr->tr_num_buf++;
 	list_add(&bd->bd_list_tr, &tr->tr_list_buf);
 	gfs2_log_unlock(sdp);

 	if (!list_empty(&le->le_list))
 		return;

 	gfs2_trans_add_gl(bd->bd_gl);

 	gfs2_meta_check(sdp, bd->bd_bh);
 	gfs2_pin(sdp, bd->bd_bh);
 	gfs2_log_lock(sdp);
 	sdp->sd_log_num_buf++;
 	list_add(&le->le_list, &sdp->sd_log_le_buf);
 	gfs2_log_unlock(sdp);

 	tr->tr_num_buf_new++;
 }

 static void buf_lo_incore_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 {
 	struct list_head *head = &tr->tr_list_buf;
 	struct gfs2_bufdata *bd;

 	gfs2_log_lock(sdp);
 	while (!list_empty(head)) {
 		bd = list_entry(head->next, struct gfs2_bufdata, bd_list_tr);
 		list_del_init(&bd->bd_list_tr);
 		tr->tr_num_buf--;
 	}
 	gfs2_log_unlock(sdp);
 	gfs2_assert_warn(sdp, !tr->tr_num_buf);
 }

 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 = sdp->sd_log_num_buf;
 	unsigned int offset = BUF_OFFSET;
 	unsigned int limit;
 	unsigned int num;
 	unsigned n;
 	__be64 *ptr;

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

 	bd1 = bd2 = list_prepare_entry(bd1, &sdp->sd_log_le_buf, bd_le.le_list);
 	while(total) {
 		num = total;
 		if (total > limit)
 			num = limit;
 		bh = gfs2_log_get_buf(sdp);
 		ld = (struct gfs2_log_descriptor *)bh->b_data;
 		ptr = (__be64 *)(bh->b_data + offset);
 		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(GFS2_LOG_DESC_METADATA);
 		ld->ld_length = cpu_to_be32(num + 1);
 		ld->ld_data1 = cpu_to_be32(num);
 		ld->ld_data2 = cpu_to_be32(0);
 		memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));

 		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;
 		}

 		set_buffer_dirty(bh);
 		ll_rw_block(WRITE, 1, &bh);

 		n = 0;
 		list_for_each_entry_continue(bd2, &sdp->sd_log_le_buf,
 					     bd_le.le_list) {
 			bh = gfs2_log_fake_buf(sdp, bd2->bd_bh);
 			set_buffer_dirty(bh);
 			ll_rw_block(WRITE, 1, &bh);
 			if (++n >= num)
 				break;
 		}

 		total -= num;
 	}
 }

 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++;

 	gfs2_log_lock(sdp);
 	sdp->sd_log_num_revoke++;
 	list_add(&le->le_list, &sdp->sd_log_le_revoke);
 	gfs2_log_unlock(sdp);
 }

 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_revoke *rv;

 	if (!sdp->sd_log_num_revoke)
 		return;

 	bh = gfs2_log_get_buf(sdp);
 	ld = (struct gfs2_log_descriptor *)bh->b_data;
 	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(GFS2_LOG_DESC_REVOKE);
 	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);
 	ld->ld_data2 = cpu_to_be32(0);
 	memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));
 	offset = sizeof(struct gfs2_log_descriptor);

 	while (!list_empty(head)) {
 		rv = list_entry(head->next, struct gfs2_revoke, rv_le.le_list);
 		list_del_init(&rv->rv_le.le_list);
 		sdp->sd_log_num_revoke--;

 		if (offset + sizeof(u64) > sdp->sd_sb.sb_bsize) {
 			set_buffer_dirty(bh);
 			ll_rw_block(WRITE, 1, &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(rv->rv_blkno);
 		kfree(rv);

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

 	set_buffer_dirty(bh);
 	ll_rw_block(WRITE, 1, &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)
 				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);

 	gfs2_log_lock(sdp);
 	if (!list_empty(&bd->bd_list_tr)) {
 		gfs2_log_unlock(sdp);
 		return;
 	}
 	tr->tr_touched = 1;
 	if (gfs2_is_jdata(ip)) {
 		tr->tr_num_buf++;
 		list_add(&bd->bd_list_tr, &tr->tr_list_buf);
 	}
 	gfs2_log_unlock(sdp);
 	if (!list_empty(&le->le_list))
 		return;

 	gfs2_trans_add_gl(bd->bd_gl);
 	if (gfs2_is_jdata(ip)) {
 		sdp->sd_log_num_jdata++;
 		gfs2_pin(sdp, bd->bd_bh);
 		tr->tr_num_databuf_new++;
 	}
 	sdp->sd_log_num_databuf++;
 	gfs2_log_lock(sdp);
 	list_add(&le->le_list, &sdp->sd_log_le_databuf);
 	gfs2_log_unlock(sdp);
 }

 static int gfs2_check_magic(struct buffer_head *bh)
 {
 	struct page *page = bh->b_page;
 	void *kaddr;
 	__be32 *ptr;
 	int rv = 0;

 	kaddr = kmap_atomic(page, KM_USER0);
 	ptr = kaddr + bh_offset(bh);
 	if (*ptr == cpu_to_be32(GFS2_MAGIC))
 		rv = 1;
 	kunmap_atomic(kaddr, KM_USER0);

 	return rv;
 }

 /**
  * databuf_lo_before_commit - Scan the data buffers, writing as we go
  *
  * Here we scan through the lists of buffers and make the assumption
  * that any buffer thats been pinned is being journaled, and that
  * any unpinned buffer is an ordered write data buffer and therefore
  * will be written back rather than journaled.
  */
 static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
 {
 	LIST_HEAD(started);
 	struct gfs2_bufdata *bd1 = NULL, *bd2, *bdt;
 	struct buffer_head *bh = NULL,*bh1 = NULL;
 	struct gfs2_log_descriptor *ld;
 	unsigned int limit;
 	unsigned int total_dbuf = sdp->sd_log_num_databuf;
 	unsigned int total_jdata = sdp->sd_log_num_jdata;
 	unsigned int num, n;
 	__be64 *ptr = NULL;

 	limit = databuf_limit(sdp);

 	/*
 	 * Start writing ordered buffers, write journaled buffers
 	 * into the log along with a header
 	 */
 	gfs2_log_lock(sdp);
 	bd2 = bd1 = list_prepare_entry(bd1, &sdp->sd_log_le_databuf,
 				       bd_le.le_list);
 	while(total_dbuf) {
 		num = total_jdata;
 		if (num > limit)
 			num = limit;
 		n = 0;
 		list_for_each_entry_safe_continue(bd1, bdt,
 						  &sdp->sd_log_le_databuf,
 						  bd_le.le_list) {
 			/* store off the buffer head in a local ptr since
 			 * gfs2_bufdata might change when we drop the log lock
 			 */
 			bh1 = bd1->bd_bh;

 			/* An ordered write buffer */
 			if (bh1 && !buffer_pinned(bh1)) {
 				list_move(&bd1->bd_le.le_list, &started);
 				if (bd1 == bd2) {
 					bd2 = NULL;
 					bd2 = list_prepare_entry(bd2,
 							&sdp->sd_log_le_databuf,
 							bd_le.le_list);
 				}
 				total_dbuf--;
 				if (bh1) {
 					if (buffer_dirty(bh1)) {
 						get_bh(bh1);

 						gfs2_log_unlock(sdp);

 						ll_rw_block(SWRITE, 1, &bh1);
 						brelse(bh1);

 						gfs2_log_lock(sdp);
 					}
 					continue;
 				}
 				continue;
 			} else if (bh1) { /* A journaled buffer */
 				int magic;
 				gfs2_log_unlock(sdp);
 				if (!bh) {
 					bh = gfs2_log_get_buf(sdp);
 					ld = (struct gfs2_log_descriptor *)
 					     bh->b_data;
 					ptr = (__be64 *)(bh->b_data +
 							 DATABUF_OFFSET);
 					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(GFS2_LOG_DESC_JDATA);
 					ld->ld_length = cpu_to_be32(num + 1);
 					ld->ld_data1 = cpu_to_be32(num);
 					ld->ld_data2 = cpu_to_be32(0);
 					memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));
 				}
 				magic = gfs2_check_magic(bh1);
 				*ptr++ = cpu_to_be64(bh1->b_blocknr);
 				*ptr++ = cpu_to_be64((__u64)magic);
 				clear_buffer_escaped(bh1);
 				if (unlikely(magic != 0))
 					set_buffer_escaped(bh1);
 				gfs2_log_lock(sdp);
 				if (++n >= num)
 					break;
 			} else if (!bh1) {
 				total_dbuf--;
 				sdp->sd_log_num_databuf--;
 				list_del_init(&bd1->bd_le.le_list);
 				if (bd1 == bd2) {
 					bd2 = NULL;
 					bd2 = list_prepare_entry(bd2,
 						&sdp->sd_log_le_databuf,
 						bd_le.le_list);
                                 }
 				kmem_cache_free(gfs2_bufdata_cachep, bd1);
 			}
 		}
 		gfs2_log_unlock(sdp);
 		if (bh) {
 			set_buffer_mapped(bh);
 			set_buffer_dirty(bh);
 			ll_rw_block(WRITE, 1, &bh);
 			bh = NULL;
 		}
 		n = 0;
 		gfs2_log_lock(sdp);
 		list_for_each_entry_continue(bd2, &sdp->sd_log_le_databuf,
 					     bd_le.le_list) {
 			if (!bd2->bd_bh)
 				continue;
 			/* copy buffer if it needs escaping */
 			gfs2_log_unlock(sdp);
 			if (unlikely(buffer_escaped(bd2->bd_bh))) {
 				void *kaddr;
 				struct page *page = bd2->bd_bh->b_page;
 				bh = gfs2_log_get_buf(sdp);
 				kaddr = kmap_atomic(page, KM_USER0);
 				memcpy(bh->b_data,
 				       kaddr + bh_offset(bd2->bd_bh),
 				       sdp->sd_sb.sb_bsize);
 				kunmap_atomic(kaddr, KM_USER0);
 				*(__be32 *)bh->b_data = 0;
 			} else {
 				bh = gfs2_log_fake_buf(sdp, bd2->bd_bh);
 			}
 			set_buffer_dirty(bh);
 			ll_rw_block(WRITE, 1, &bh);
 			gfs2_log_lock(sdp);
 			if (++n >= num)
 				break;
 		}
 		bh = NULL;
 		total_dbuf -= num;
 		total_jdata -= num;
 	}
 	gfs2_log_unlock(sdp);

 	/* Wait on all ordered buffers */
 	while (!list_empty(&started)) {
 		gfs2_log_lock(sdp);
 		bd1 = list_entry(started.next, struct gfs2_bufdata,
 				 bd_le.le_list);
 		list_del_init(&bd1->bd_le.le_list);
 		sdp->sd_log_num_databuf--;
 		bh = bd1->bd_bh;
 		if (bh) {
 			bh->b_private = NULL;
 			get_bh(bh);
 			gfs2_log_unlock(sdp);
 			wait_on_buffer(bh);
 			brelse(bh);
 		} else
 			gfs2_log_unlock(sdp);

 		kmem_cache_free(gfs2_bufdata_cachep, bd1);
 	}

 	/* We've removed all the ordered write bufs here, so only jdata left */
 	gfs2_assert_warn(sdp, sdp->sd_log_num_databuf == sdp->sd_log_num_jdata);
 }

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


 const struct gfs2_log_operations gfs2_glock_lops = {
 	.lo_add = glock_lo_add,
 	.lo_after_commit = glock_lo_after_commit,
 	.lo_name = "glock",
 };

 const struct gfs2_log_operations gfs2_buf_lops = {
 	.lo_add = buf_lo_add,
 	.lo_incore_commit = buf_lo_incore_commit,
 	.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_incore_commit = buf_lo_incore_commit,
 	.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_glock_lops,
 	&gfs2_buf_lops,
 	&gfs2_revoke_lops,
 	&gfs2_rg_lops,
 	&gfs2_databuf_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/lm_interface.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"

	static void glock_lo_add(struct gfs2_sbd sdp, struct gfs2_log_element le)
	{
	struct gfs2_glock *gl;
	struct gfs2_trans *tr = current->journal_info;

	tr->tr_touched = 1;

	gl = container_of(le, struct gfs2_glock, gl_le);
	if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(gl)))
	return;

	gfs2_log_lock(sdp);
	if (!list_empty(&le->le_list)){
	gfs2_log_unlock(sdp);
	return;
	}
	gfs2_glock_hold(gl);
	set_bit(GLF_DIRTY, &gl->gl_flags);
	sdp->sd_log_num_gl++;
	list_add(&le->le_list, &sdp->sd_log_le_gl);
	gfs2_log_unlock(sdp);
	}

	static void glock_lo_after_commit(struct gfs2_sbd sdp, struct gfs2_ail ai)
	{
	struct list_head *head = &sdp->sd_log_le_gl;
	struct gfs2_glock *gl;

	while (!list_empty(head)) {
	gl = list_entry(head->next, struct gfs2_glock, gl_le.le_list);
	list_del_init(&gl->gl_le.le_list);
	sdp->sd_log_num_gl--;

	gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(gl));
	gfs2_glock_put(gl);
	}
	gfs2_assert_warn(sdp, !sdp->sd_log_num_gl);
	}

	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_trans *tr;

	gfs2_log_lock(sdp);
	if (!list_empty(&bd->bd_list_tr)) {
	gfs2_log_unlock(sdp);
	return;
	}
	tr = current->journal_info;
	tr->tr_touched = 1;
	tr->tr_num_buf++;
	list_add(&bd->bd_list_tr, &tr->tr_list_buf);
	gfs2_log_unlock(sdp);

	if (!list_empty(&le->le_list))
	return;

	gfs2_trans_add_gl(bd->bd_gl);

	gfs2_meta_check(sdp, bd->bd_bh);
	gfs2_pin(sdp, bd->bd_bh);
	gfs2_log_lock(sdp);
	sdp->sd_log_num_buf++;
	list_add(&le->le_list, &sdp->sd_log_le_buf);
	gfs2_log_unlock(sdp);

	tr->tr_num_buf_new++;
	}

	static void buf_lo_incore_commit(struct gfs2_sbd sdp, struct gfs2_trans tr)
	{
	struct list_head *head = &tr->tr_list_buf;
	struct gfs2_bufdata *bd;

	gfs2_log_lock(sdp);
	while (!list_empty(head)) {
	bd = list_entry(head->next, struct gfs2_bufdata, bd_list_tr);
	list_del_init(&bd->bd_list_tr);
	tr->tr_num_buf--;
	}
	gfs2_log_unlock(sdp);
	gfs2_assert_warn(sdp, !tr->tr_num_buf);
	}

	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 = sdp->sd_log_num_buf;
	unsigned int offset = BUF_OFFSET;
	unsigned int limit;
	unsigned int num;
	unsigned n;
	__be64 *ptr;

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

	bd1 = bd2 = list_prepare_entry(bd1, &sdp->sd_log_le_buf, bd_le.le_list);
	while(total) {
	num = total;
	if (total > limit)
	num = limit;
	bh = gfs2_log_get_buf(sdp);
	ld = (struct gfs2_log_descriptor *)bh->b_data;
	ptr = (__be64 *)(bh->b_data + offset);
	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(GFS2_LOG_DESC_METADATA);
	ld->ld_length = cpu_to_be32(num + 1);
	ld->ld_data1 = cpu_to_be32(num);
	ld->ld_data2 = cpu_to_be32(0);
	memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));

	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;
	}

	set_buffer_dirty(bh);
	ll_rw_block(WRITE, 1, &bh);

	n = 0;
	list_for_each_entry_continue(bd2, &sdp->sd_log_le_buf,
	bd_le.le_list) {
	bh = gfs2_log_fake_buf(sdp, bd2->bd_bh);
	set_buffer_dirty(bh);
	ll_rw_block(WRITE, 1, &bh);
	if (++n >= num)
	break;
	}

	total -= num;
	}
	}

	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++;

	gfs2_log_lock(sdp);
	sdp->sd_log_num_revoke++;
	list_add(&le->le_list, &sdp->sd_log_le_revoke);
	gfs2_log_unlock(sdp);
	}

	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_revoke *rv;

	if (!sdp->sd_log_num_revoke)
	return;

	bh = gfs2_log_get_buf(sdp);
	ld = (struct gfs2_log_descriptor *)bh->b_data;
	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(GFS2_LOG_DESC_REVOKE);
	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);
	ld->ld_data2 = cpu_to_be32(0);
	memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));
	offset = sizeof(struct gfs2_log_descriptor);

	while (!list_empty(head)) {
	rv = list_entry(head->next, struct gfs2_revoke, rv_le.le_list);
	list_del_init(&rv->rv_le.le_list);
	sdp->sd_log_num_revoke--;

	if (offset + sizeof(u64) > sdp->sd_sb.sb_bsize) {
	set_buffer_dirty(bh);
	ll_rw_block(WRITE, 1, &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(rv->rv_blkno);
	kfree(rv);

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

	set_buffer_dirty(bh);
	ll_rw_block(WRITE, 1, &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)
	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);

	gfs2_log_lock(sdp);
	if (!list_empty(&bd->bd_list_tr)) {
	gfs2_log_unlock(sdp);
	return;
	}
	tr->tr_touched = 1;
	if (gfs2_is_jdata(ip)) {
	tr->tr_num_buf++;
	list_add(&bd->bd_list_tr, &tr->tr_list_buf);
	}
	gfs2_log_unlock(sdp);
	if (!list_empty(&le->le_list))
	return;

	gfs2_trans_add_gl(bd->bd_gl);
	if (gfs2_is_jdata(ip)) {
	sdp->sd_log_num_jdata++;
	gfs2_pin(sdp, bd->bd_bh);
	tr->tr_num_databuf_new++;
	}
	sdp->sd_log_num_databuf++;
	gfs2_log_lock(sdp);
	list_add(&le->le_list, &sdp->sd_log_le_databuf);
	gfs2_log_unlock(sdp);
	}

	static int gfs2_check_magic(struct buffer_head *bh)
	{
	struct page *page = bh->b_page;
	void *kaddr;
	__be32 *ptr;
	int rv = 0;

	kaddr = kmap_atomic(page, KM_USER0);
	ptr = kaddr + bh_offset(bh);
	if (*ptr == cpu_to_be32(GFS2_MAGIC))
	rv = 1;
	kunmap_atomic(kaddr, KM_USER0);

	return rv;
	}

	/**
	* databuf_lo_before_commit - Scan the data buffers, writing as we go
	*
	* Here we scan through the lists of buffers and make the assumption
	* that any buffer thats been pinned is being journaled, and that
	* any unpinned buffer is an ordered write data buffer and therefore
	* will be written back rather than journaled.
	*/
	static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
	{
	LIST_HEAD(started);
	struct gfs2_bufdata bd1 = NULL, bd2, *bdt;
	struct buffer_head bh = NULL,bh1 = NULL;
	struct gfs2_log_descriptor *ld;
	unsigned int limit;
	unsigned int total_dbuf = sdp->sd_log_num_databuf;
	unsigned int total_jdata = sdp->sd_log_num_jdata;
	unsigned int num, n;
	__be64 *ptr = NULL;

	limit = databuf_limit(sdp);

	/*
	* Start writing ordered buffers, write journaled buffers
	* into the log along with a header
	*/
	gfs2_log_lock(sdp);
	bd2 = bd1 = list_prepare_entry(bd1, &sdp->sd_log_le_databuf,
	bd_le.le_list);
	while(total_dbuf) {
	num = total_jdata;
	if (num > limit)
	num = limit;
	n = 0;
	list_for_each_entry_safe_continue(bd1, bdt,
	&sdp->sd_log_le_databuf,
	bd_le.le_list) {
	/* store off the buffer head in a local ptr since
	* gfs2_bufdata might change when we drop the log lock
	*/
	bh1 = bd1->bd_bh;

	/* An ordered write buffer */
	if (bh1 && !buffer_pinned(bh1)) {
	list_move(&bd1->bd_le.le_list, &started);
	if (bd1 == bd2) {
	bd2 = NULL;
	bd2 = list_prepare_entry(bd2,
	&sdp->sd_log_le_databuf,
	bd_le.le_list);
	}
	total_dbuf--;
	if (bh1) {
	if (buffer_dirty(bh1)) {
	get_bh(bh1);

	gfs2_log_unlock(sdp);

	ll_rw_block(SWRITE, 1, &bh1);
	brelse(bh1);

	gfs2_log_lock(sdp);
	}
	continue;
	}
	continue;
	} else if (bh1) { /* A journaled buffer */
	int magic;
	gfs2_log_unlock(sdp);
	if (!bh) {
	bh = gfs2_log_get_buf(sdp);
	ld = (struct gfs2_log_descriptor *)
	bh->b_data;
	ptr = (__be64 *)(bh->b_data +
	DATABUF_OFFSET);
	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(GFS2_LOG_DESC_JDATA);
	ld->ld_length = cpu_to_be32(num + 1);
	ld->ld_data1 = cpu_to_be32(num);
	ld->ld_data2 = cpu_to_be32(0);
	memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));
	}
	magic = gfs2_check_magic(bh1);
	*ptr++ = cpu_to_be64(bh1->b_blocknr);
	*ptr++ = cpu_to_be64((__u64)magic);
	clear_buffer_escaped(bh1);
	if (unlikely(magic != 0))
	set_buffer_escaped(bh1);
	gfs2_log_lock(sdp);
	if (++n >= num)
	break;
	} else if (!bh1) {
	total_dbuf--;
	sdp->sd_log_num_databuf--;
	list_del_init(&bd1->bd_le.le_list);
	if (bd1 == bd2) {
	bd2 = NULL;
	bd2 = list_prepare_entry(bd2,
	&sdp->sd_log_le_databuf,
	bd_le.le_list);
	}
	kmem_cache_free(gfs2_bufdata_cachep, bd1);
	}
	}
	gfs2_log_unlock(sdp);
	if (bh) {
	set_buffer_mapped(bh);
	set_buffer_dirty(bh);
	ll_rw_block(WRITE, 1, &bh);
	bh = NULL;
	}
	n = 0;
	gfs2_log_lock(sdp);
	list_for_each_entry_continue(bd2, &sdp->sd_log_le_databuf,
	bd_le.le_list) {
	if (!bd2->bd_bh)
	continue;
	/* copy buffer if it needs escaping */
	gfs2_log_unlock(sdp);
	if (unlikely(buffer_escaped(bd2->bd_bh))) {
	void *kaddr;
	struct page *page = bd2->bd_bh->b_page;
	bh = gfs2_log_get_buf(sdp);
	kaddr = kmap_atomic(page, KM_USER0);
	memcpy(bh->b_data,
	kaddr + bh_offset(bd2->bd_bh),
	sdp->sd_sb.sb_bsize);
	kunmap_atomic(kaddr, KM_USER0);
	(__be32 )bh->b_data = 0;
	} else {
	bh = gfs2_log_fake_buf(sdp, bd2->bd_bh);
	}
	set_buffer_dirty(bh);
	ll_rw_block(WRITE, 1, &bh);
	gfs2_log_lock(sdp);
	if (++n >= num)
	break;
	}
	bh = NULL;
	total_dbuf -= num;
	total_jdata -= num;
	}
	gfs2_log_unlock(sdp);

	/* Wait on all ordered buffers */
	while (!list_empty(&started)) {
	gfs2_log_lock(sdp);
	bd1 = list_entry(started.next, struct gfs2_bufdata,
	bd_le.le_list);
	list_del_init(&bd1->bd_le.le_list);
	sdp->sd_log_num_databuf--;
	bh = bd1->bd_bh;
	if (bh) {
	bh->b_private = NULL;
	get_bh(bh);
	gfs2_log_unlock(sdp);
	wait_on_buffer(bh);
	brelse(bh);
	} else
	gfs2_log_unlock(sdp);

	kmem_cache_free(gfs2_bufdata_cachep, bd1);
	}

	/* We've removed all the ordered write bufs here, so only jdata left */
	gfs2_assert_warn(sdp, sdp->sd_log_num_databuf == sdp->sd_log_num_jdata);
	}

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


	const struct gfs2_log_operations gfs2_glock_lops = {
	.lo_add = glock_lo_add,
	.lo_after_commit = glock_lo_after_commit,
	.lo_name = "glock",
	};

	const struct gfs2_log_operations gfs2_buf_lops = {
	.lo_add = buf_lo_add,
	.lo_incore_commit = buf_lo_incore_commit,
	.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_incore_commit = buf_lo_incore_commit,
	.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_glock_lops,
	&gfs2_buf_lops,
	&gfs2_revoke_lops,
	&gfs2_rg_lops,
	&gfs2_databuf_lops,
	NULL,
	};