Initial import

1 files changed, 950 insertions, 0 deletions

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
new file mode 100644
index 000000000..536e7a625
--- /dev/null
+++ b/fs/gfs2/log.c
@@ -0,0 +1,950 @@
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2007 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/crc32.h>
+#include <linux/delay.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/writeback.h>
+#include <linux/list_sort.h>
+
+#include "gfs2.h"
+#include "incore.h"
+#include "bmap.h"
+#include "glock.h"
+#include "log.h"
+#include "lops.h"
+#include "meta_io.h"
+#include "util.h"
+#include "dir.h"
+#include "trace_gfs2.h"
+
+/**
+ * gfs2_struct2blk - compute stuff
+ * @sdp: the filesystem
+ * @nstruct: the number of structures
+ * @ssize: the size of the structures
+ *
+ * Compute the number of log descriptor blocks needed to hold a certain number
+ * of structures of a certain size.
+ *
+ * Returns: the number of blocks needed (minimum is always 1)
+ */
+
+unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct,
+			     unsigned int ssize)
+{
+	unsigned int blks;
+	unsigned int first, second;
+
+	blks = 1;
+	first = (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_log_descriptor)) / ssize;
+
+	if (nstruct > first) {
+		second = (sdp->sd_sb.sb_bsize -
+			  sizeof(struct gfs2_meta_header)) / ssize;
+		blks += DIV_ROUND_UP(nstruct - first, second);
+	}
+
+	return blks;
+}
+
+/**
+ * gfs2_remove_from_ail - Remove an entry from the ail lists, updating counters
+ * @mapping: The associated mapping (maybe NULL)
+ * @bd: The gfs2_bufdata to remove
+ *
+ * The ail lock _must_ be held when calling this function
+ *
+ */
+
+void gfs2_remove_from_ail(struct gfs2_bufdata *bd)
+{
+	bd->bd_tr = NULL;
+	list_del_init(&bd->bd_ail_st_list);
+	list_del_init(&bd->bd_ail_gl_list);
+	atomic_dec(&bd->bd_gl->gl_ail_count);
+	brelse(bd->bd_bh);
+}
+
+/**
+ * gfs2_ail1_start_one - Start I/O on a part of the AIL
+ * @sdp: the filesystem
+ * @wbc: The writeback control structure
+ * @ai: The ail structure
+ *
+ */
+
+static int gfs2_ail1_start_one(struct gfs2_sbd *sdp,
+			       struct writeback_control *wbc,
+			       struct gfs2_trans *tr)
+__releases(&sdp->sd_ail_lock)
+__acquires(&sdp->sd_ail_lock)
+{
+	struct gfs2_glock *gl = NULL;
+	struct address_space *mapping;
+	struct gfs2_bufdata *bd, *s;
+	struct buffer_head *bh;
+
+	list_for_each_entry_safe_reverse(bd, s, &tr->tr_ail1_list, bd_ail_st_list) {
+		bh = bd->bd_bh;
+
+		gfs2_assert(sdp, bd->bd_tr == tr);
+
+		if (!buffer_busy(bh)) {
+			if (!buffer_uptodate(bh))
+				gfs2_io_error_bh(sdp, bh);
+			list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
+			continue;
+		}
+
+		if (!buffer_dirty(bh))
+			continue;
+		if (gl == bd->bd_gl)
+			continue;
+		gl = bd->bd_gl;
+		list_move(&bd->bd_ail_st_list, &tr->tr_ail1_list);
+		mapping = bh->b_page->mapping;
+		if (!mapping)
+			continue;
+		spin_unlock(&sdp->sd_ail_lock);
+		generic_writepages(mapping, wbc);
+		spin_lock(&sdp->sd_ail_lock);
+		if (wbc->nr_to_write <= 0)
+			break;
+		return 1;
+	}
+
+	return 0;
+}
+
+
+/**
+ * gfs2_ail1_flush - start writeback of some ail1 entries 
+ * @sdp: The super block
+ * @wbc: The writeback control structure
+ *
+ * Writes back some ail1 entries, according to the limits in the
+ * writeback control structure
+ */
+
+void gfs2_ail1_flush(struct gfs2_sbd *sdp, struct writeback_control *wbc)
+{
+	struct list_head *head = &sdp->sd_ail1_list;
+	struct gfs2_trans *tr;
+	struct blk_plug plug;
+
+	trace_gfs2_ail_flush(sdp, wbc, 1);
+	blk_start_plug(&plug);
+	spin_lock(&sdp->sd_ail_lock);
+restart:
+	list_for_each_entry_reverse(tr, head, tr_list) {
+		if (wbc->nr_to_write <= 0)
+			break;
+		if (gfs2_ail1_start_one(sdp, wbc, tr))
+			goto restart;
+	}
+	spin_unlock(&sdp->sd_ail_lock);
+	blk_finish_plug(&plug);
+	trace_gfs2_ail_flush(sdp, wbc, 0);
+}
+
+/**
+ * gfs2_ail1_start - start writeback of all ail1 entries
+ * @sdp: The superblock
+ */
+
+static void gfs2_ail1_start(struct gfs2_sbd *sdp)
+{
+	struct writeback_control wbc = {
+		.sync_mode = WB_SYNC_NONE,
+		.nr_to_write = LONG_MAX,
+		.range_start = 0,
+		.range_end = LLONG_MAX,
+	};
+
+	return gfs2_ail1_flush(sdp, &wbc);
+}
+
+/**
+ * gfs2_ail1_empty_one - Check whether or not a trans in the AIL has been synced
+ * @sdp: the filesystem
+ * @ai: the AIL entry
+ *
+ */
+
+static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
+{
+	struct gfs2_bufdata *bd, *s;
+	struct buffer_head *bh;
+
+	list_for_each_entry_safe_reverse(bd, s, &tr->tr_ail1_list,
+					 bd_ail_st_list) {
+		bh = bd->bd_bh;
+		gfs2_assert(sdp, bd->bd_tr == tr);
+		if (buffer_busy(bh))
+			continue;
+		if (!buffer_uptodate(bh))
+			gfs2_io_error_bh(sdp, bh);
+		list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
+	}
+
+}
+
+/**
+ * gfs2_ail1_empty - Try to empty the ail1 lists
+ * @sdp: The superblock
+ *
+ * Tries to empty the ail1 lists, starting with the oldest first
+ */
+
+static int gfs2_ail1_empty(struct gfs2_sbd *sdp)
+{
+	struct gfs2_trans *tr, *s;
+	int oldest_tr = 1;
+	int ret;
+
+	spin_lock(&sdp->sd_ail_lock);
+	list_for_each_entry_safe_reverse(tr, s, &sdp->sd_ail1_list, tr_list) {
+		gfs2_ail1_empty_one(sdp, tr);
+		if (list_empty(&tr->tr_ail1_list) && oldest_tr)
+			list_move(&tr->tr_list, &sdp->sd_ail2_list);
+		else
+			oldest_tr = 0;
+	}
+	ret = list_empty(&sdp->sd_ail1_list);
+	spin_unlock(&sdp->sd_ail_lock);
+
+	return ret;
+}
+
+static void gfs2_ail1_wait(struct gfs2_sbd *sdp)
+{
+	struct gfs2_trans *tr;
+	struct gfs2_bufdata *bd;
+	struct buffer_head *bh;
+
+	spin_lock(&sdp->sd_ail_lock);
+	list_for_each_entry_reverse(tr, &sdp->sd_ail1_list, tr_list) {
+		list_for_each_entry(bd, &tr->tr_ail1_list, bd_ail_st_list) {
+			bh = bd->bd_bh;
+			if (!buffer_locked(bh))
+				continue;
+			get_bh(bh);
+			spin_unlock(&sdp->sd_ail_lock);
+			wait_on_buffer(bh);
+			brelse(bh);
+			return;
+		}
+	}
+	spin_unlock(&sdp->sd_ail_lock);
+}
+
+/**
+ * gfs2_ail2_empty_one - Check whether or not a trans in the AIL has been synced
+ * @sdp: the filesystem
+ * @ai: the AIL entry
+ *
+ */
+
+static void gfs2_ail2_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
+{
+	struct list_head *head = &tr->tr_ail2_list;
+	struct gfs2_bufdata *bd;
+
+	while (!list_empty(head)) {
+		bd = list_entry(head->prev, struct gfs2_bufdata,
+				bd_ail_st_list);
+		gfs2_assert(sdp, bd->bd_tr == tr);
+		gfs2_remove_from_ail(bd);
+	}
+}
+
+static void ail2_empty(struct gfs2_sbd *sdp, unsigned int new_tail)
+{
+	struct gfs2_trans *tr, *safe;
+	unsigned int old_tail = sdp->sd_log_tail;
+	int wrap = (new_tail < old_tail);
+	int a, b, rm;
+
+	spin_lock(&sdp->sd_ail_lock);
+
+	list_for_each_entry_safe(tr, safe, &sdp->sd_ail2_list, tr_list) {
+		a = (old_tail <= tr->tr_first);
+		b = (tr->tr_first < new_tail);
+		rm = (wrap) ? (a || b) : (a && b);
+		if (!rm)
+			continue;
+
+		gfs2_ail2_empty_one(sdp, tr);
+		list_del(&tr->tr_list);
+		gfs2_assert_warn(sdp, list_empty(&tr->tr_ail1_list));
+		gfs2_assert_warn(sdp, list_empty(&tr->tr_ail2_list));
+		kfree(tr);
+	}
+
+	spin_unlock(&sdp->sd_ail_lock);
+}
+
+/**
+ * gfs2_log_release - Release a given number of log blocks
+ * @sdp: The GFS2 superblock
+ * @blks: The number of blocks
+ *
+ */
+
+void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks)
+{
+
+	atomic_add(blks, &sdp->sd_log_blks_free);
+	trace_gfs2_log_blocks(sdp, blks);
+	gfs2_assert_withdraw(sdp, atomic_read(&sdp->sd_log_blks_free) <=
+				  sdp->sd_jdesc->jd_blocks);
+	up_read(&sdp->sd_log_flush_lock);
+}
+
+/**
+ * gfs2_log_reserve - Make a log reservation
+ * @sdp: The GFS2 superblock
+ * @blks: The number of blocks to reserve
+ *
+ * Note that we never give out the last few blocks of the journal. Thats
+ * due to the fact that there is a small number of header blocks
+ * associated with each log flush. The exact number can't be known until
+ * flush time, so we ensure that we have just enough free blocks at all
+ * times to avoid running out during a log flush.
+ *
+ * We no longer flush the log here, instead we wake up logd to do that
+ * for us. To avoid the thundering herd and to ensure that we deal fairly
+ * with queued waiters, we use an exclusive wait. This means that when we
+ * get woken with enough journal space to get our reservation, we need to
+ * wake the next waiter on the list.
+ *
+ * Returns: errno
+ */
+
+int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks)
+{
+	int ret = 0;
+	unsigned reserved_blks = 7 * (4096 / sdp->sd_vfs->s_blocksize);
+	unsigned wanted = blks + reserved_blks;
+	DEFINE_WAIT(wait);
+	int did_wait = 0;
+	unsigned int free_blocks;
+
+	if (gfs2_assert_warn(sdp, blks) ||
+	    gfs2_assert_warn(sdp, blks <= sdp->sd_jdesc->jd_blocks))
+		return -EINVAL;
+retry:
+	free_blocks = atomic_read(&sdp->sd_log_blks_free);
+	if (unlikely(free_blocks <= wanted)) {
+		do {
+			prepare_to_wait_exclusive(&sdp->sd_log_waitq, &wait,
+					TASK_UNINTERRUPTIBLE);
+			wake_up(&sdp->sd_logd_waitq);
+			did_wait = 1;
+			if (atomic_read(&sdp->sd_log_blks_free) <= wanted)
+				io_schedule();
+			free_blocks = atomic_read(&sdp->sd_log_blks_free);
+		} while(free_blocks <= wanted);
+		finish_wait(&sdp->sd_log_waitq, &wait);
+	}
+	atomic_inc(&sdp->sd_reserving_log);
+	if (atomic_cmpxchg(&sdp->sd_log_blks_free, free_blocks,
+				free_blocks - blks) != free_blocks) {
+		if (atomic_dec_and_test(&sdp->sd_reserving_log))
+			wake_up(&sdp->sd_reserving_log_wait);
+		goto retry;
+	}
+	trace_gfs2_log_blocks(sdp, -blks);
+
+	/*
+	 * If we waited, then so might others, wake them up _after_ we get
+	 * our share of the log.
+	 */
+	if (unlikely(did_wait))
+		wake_up(&sdp->sd_log_waitq);
+
+	down_read(&sdp->sd_log_flush_lock);
+	if (unlikely(!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))) {
+		gfs2_log_release(sdp, blks);
+		ret = -EROFS;
+	}
+	if (atomic_dec_and_test(&sdp->sd_reserving_log))
+		wake_up(&sdp->sd_reserving_log_wait);
+	return ret;
+}
+
+/**
+ * log_distance - Compute distance between two journal blocks
+ * @sdp: The GFS2 superblock
+ * @newer: The most recent journal block of the pair
+ * @older: The older journal block of the pair
+ *
+ *   Compute the distance (in the journal direction) between two
+ *   blocks in the journal
+ *
+ * Returns: the distance in blocks
+ */
+
+static inline unsigned int log_distance(struct gfs2_sbd *sdp, unsigned int newer,
+					unsigned int older)
+{
+	int dist;
+
+	dist = newer - older;
+	if (dist < 0)
+		dist += sdp->sd_jdesc->jd_blocks;
+
+	return dist;
+}
+
+/**
+ * calc_reserved - Calculate the number of blocks to reserve when
+ *                 refunding a transaction's unused buffers.
+ * @sdp: The GFS2 superblock
+ *
+ * This is complex.  We need to reserve room for all our currently used
+ * metadata buffers (e.g. normal file I/O rewriting file time stamps) and 
+ * all our journaled data buffers for journaled files (e.g. files in the 
+ * meta_fs like rindex, or files for which chattr +j was done.)
+ * If we don't reserve enough space, gfs2_log_refund and gfs2_log_flush
+ * will count it as free space (sd_log_blks_free) and corruption will follow.
+ *
+ * We can have metadata bufs and jdata bufs in the same journal.  So each
+ * type gets its own log header, for which we need to reserve a block.
+ * In fact, each type has the potential for needing more than one header 
+ * in cases where we have more buffers than will fit on a journal page.
+ * Metadata journal entries take up half the space of journaled buffer entries.
+ * Thus, metadata entries have buf_limit (502) and journaled buffers have
+ * databuf_limit (251) before they cause a wrap around.
+ *
+ * Also, we need to reserve blocks for revoke journal entries and one for an
+ * overall header for the lot.
+ *
+ * Returns: the number of blocks reserved
+ */
+static unsigned int calc_reserved(struct gfs2_sbd *sdp)
+{
+	unsigned int reserved = 0;
+	unsigned int mbuf;
+	unsigned int dbuf;
+	struct gfs2_trans *tr = sdp->sd_log_tr;
+
+	if (tr) {
+		mbuf = tr->tr_num_buf_new - tr->tr_num_buf_rm;
+		dbuf = tr->tr_num_databuf_new - tr->tr_num_databuf_rm;
+		reserved = mbuf + dbuf;
+		/* Account for header blocks */
+		reserved += DIV_ROUND_UP(mbuf, buf_limit(sdp));
+		reserved += DIV_ROUND_UP(dbuf, databuf_limit(sdp));
+	}
+
+	if (sdp->sd_log_commited_revoke > 0)
+		reserved += gfs2_struct2blk(sdp, sdp->sd_log_commited_revoke,
+					  sizeof(u64));
+	/* One for the overall header */
+	if (reserved)
+		reserved++;
+	return reserved;
+}
+
+static unsigned int current_tail(struct gfs2_sbd *sdp)
+{
+	struct gfs2_trans *tr;
+	unsigned int tail;
+
+	spin_lock(&sdp->sd_ail_lock);
+
+	if (list_empty(&sdp->sd_ail1_list)) {
+		tail = sdp->sd_log_head;
+	} else {
+		tr = list_entry(sdp->sd_ail1_list.prev, struct gfs2_trans,
+				tr_list);
+		tail = tr->tr_first;
+	}
+
+	spin_unlock(&sdp->sd_ail_lock);
+
+	return tail;
+}
+
+static void log_pull_tail(struct gfs2_sbd *sdp, unsigned int new_tail)
+{
+	unsigned int dist = log_distance(sdp, new_tail, sdp->sd_log_tail);
+
+	ail2_empty(sdp, new_tail);
+
+	atomic_add(dist, &sdp->sd_log_blks_free);
+	trace_gfs2_log_blocks(sdp, dist);
+	gfs2_assert_withdraw(sdp, atomic_read(&sdp->sd_log_blks_free) <=
+			     sdp->sd_jdesc->jd_blocks);
+
+	sdp->sd_log_tail = new_tail;
+}
+
+
+static void log_flush_wait(struct gfs2_sbd *sdp)
+{
+	DEFINE_WAIT(wait);
+
+	if (atomic_read(&sdp->sd_log_in_flight)) {
+		do {
+			prepare_to_wait(&sdp->sd_log_flush_wait, &wait,
+					TASK_UNINTERRUPTIBLE);
+			if (atomic_read(&sdp->sd_log_in_flight))
+				io_schedule();
+		} while(atomic_read(&sdp->sd_log_in_flight));
+		finish_wait(&sdp->sd_log_flush_wait, &wait);
+	}
+}
+
+static int ip_cmp(void *priv, struct list_head *a, struct list_head *b)
+{
+	struct gfs2_inode *ipa, *ipb;
+
+	ipa = list_entry(a, struct gfs2_inode, i_ordered);
+	ipb = list_entry(b, struct gfs2_inode, i_ordered);
+
+	if (ipa->i_no_addr < ipb->i_no_addr)
+		return -1;
+	if (ipa->i_no_addr > ipb->i_no_addr)
+		return 1;
+	return 0;
+}
+
+static void gfs2_ordered_write(struct gfs2_sbd *sdp)
+{
+	struct gfs2_inode *ip;
+	LIST_HEAD(written);
+
+	spin_lock(&sdp->sd_ordered_lock);
+	list_sort(NULL, &sdp->sd_log_le_ordered, &ip_cmp);
+	while (!list_empty(&sdp->sd_log_le_ordered)) {
+		ip = list_entry(sdp->sd_log_le_ordered.next, struct gfs2_inode, i_ordered);
+		list_move(&ip->i_ordered, &written);
+		if (ip->i_inode.i_mapping->nrpages == 0)
+			continue;
+		spin_unlock(&sdp->sd_ordered_lock);
+		filemap_fdatawrite(ip->i_inode.i_mapping);
+		spin_lock(&sdp->sd_ordered_lock);
+	}
+	list_splice(&written, &sdp->sd_log_le_ordered);
+	spin_unlock(&sdp->sd_ordered_lock);
+}
+
+static void gfs2_ordered_wait(struct gfs2_sbd *sdp)
+{
+	struct gfs2_inode *ip;
+
+	spin_lock(&sdp->sd_ordered_lock);
+	while (!list_empty(&sdp->sd_log_le_ordered)) {
+		ip = list_entry(sdp->sd_log_le_ordered.next, struct gfs2_inode, i_ordered);
+		list_del(&ip->i_ordered);
+		WARN_ON(!test_and_clear_bit(GIF_ORDERED, &ip->i_flags));
+		if (ip->i_inode.i_mapping->nrpages == 0)
+			continue;
+		spin_unlock(&sdp->sd_ordered_lock);
+		filemap_fdatawait(ip->i_inode.i_mapping);
+		spin_lock(&sdp->sd_ordered_lock);
+	}
+	spin_unlock(&sdp->sd_ordered_lock);
+}
+
+void gfs2_ordered_del_inode(struct gfs2_inode *ip)
+{
+	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
+
+	spin_lock(&sdp->sd_ordered_lock);
+	if (test_and_clear_bit(GIF_ORDERED, &ip->i_flags))
+		list_del(&ip->i_ordered);
+	spin_unlock(&sdp->sd_ordered_lock);
+}
+
+void gfs2_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
+{
+	struct buffer_head *bh = bd->bd_bh;
+	struct gfs2_glock *gl = bd->bd_gl;
+
+	bh->b_private = NULL;
+	bd->bd_blkno = bh->b_blocknr;
+	gfs2_remove_from_ail(bd); /* drops ref on bh */
+	bd->bd_bh = NULL;
+	bd->bd_ops = &gfs2_revoke_lops;
+	sdp->sd_log_num_revoke++;
+	atomic_inc(&gl->gl_revokes);
+	set_bit(GLF_LFLUSH, &gl->gl_flags);
+	list_add(&bd->bd_list, &sdp->sd_log_le_revoke);
+}
+
+void gfs2_write_revokes(struct gfs2_sbd *sdp)
+{
+	struct gfs2_trans *tr;
+	struct gfs2_bufdata *bd, *tmp;
+	int have_revokes = 0;
+	int max_revokes = (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_log_descriptor)) / sizeof(u64);
+
+	gfs2_ail1_empty(sdp);
+	spin_lock(&sdp->sd_ail_lock);
+	list_for_each_entry(tr, &sdp->sd_ail1_list, tr_list) {
+		list_for_each_entry(bd, &tr->tr_ail2_list, bd_ail_st_list) {
+			if (list_empty(&bd->bd_list)) {
+				have_revokes = 1;
+				goto done;
+			}
+		}
+	}
+done:
+	spin_unlock(&sdp->sd_ail_lock);
+	if (have_revokes == 0)
+		return;
+	while (sdp->sd_log_num_revoke > max_revokes)
+		max_revokes += (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_meta_header)) / sizeof(u64);
+	max_revokes -= sdp->sd_log_num_revoke;
+	if (!sdp->sd_log_num_revoke) {
+		atomic_dec(&sdp->sd_log_blks_free);
+		/* If no blocks have been reserved, we need to also
+		 * reserve a block for the header */
+		if (!sdp->sd_log_blks_reserved)
+			atomic_dec(&sdp->sd_log_blks_free);
+	}
+	gfs2_log_lock(sdp);
+	spin_lock(&sdp->sd_ail_lock);
+	list_for_each_entry(tr, &sdp->sd_ail1_list, tr_list) {
+		list_for_each_entry_safe(bd, tmp, &tr->tr_ail2_list, bd_ail_st_list) {
+			if (max_revokes == 0)
+				goto out_of_blocks;
+			if (!list_empty(&bd->bd_list))
+				continue;
+			gfs2_add_revoke(sdp, bd);
+			max_revokes--;
+		}
+	}
+out_of_blocks:
+	spin_unlock(&sdp->sd_ail_lock);
+	gfs2_log_unlock(sdp);
+
+	if (!sdp->sd_log_num_revoke) {
+		atomic_inc(&sdp->sd_log_blks_free);
+		if (!sdp->sd_log_blks_reserved)
+			atomic_inc(&sdp->sd_log_blks_free);
+	}
+}
+
+/**
+ * log_write_header - Get and initialize a journal header buffer
+ * @sdp: The GFS2 superblock
+ *
+ * Returns: the initialized log buffer descriptor
+ */
+
+static void log_write_header(struct gfs2_sbd *sdp, u32 flags)
+{
+	struct gfs2_log_header *lh;
+	unsigned int tail;
+	u32 hash;
+	int rw = WRITE_FLUSH_FUA | REQ_META;
+	struct page *page = mempool_alloc(gfs2_page_pool, GFP_NOIO);
+	enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);
+	lh = page_address(page);
+	clear_page(lh);
+
+	gfs2_assert_withdraw(sdp, (state != SFS_FROZEN));
+
+	tail = current_tail(sdp);
+
+	lh->lh_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
+	lh->lh_header.mh_type = cpu_to_be32(GFS2_METATYPE_LH);
+	lh->lh_header.__pad0 = cpu_to_be64(0);
+	lh->lh_header.mh_format = cpu_to_be32(GFS2_FORMAT_LH);
+	lh->lh_header.mh_jid = cpu_to_be32(sdp->sd_jdesc->jd_jid);
+	lh->lh_sequence = cpu_to_be64(sdp->sd_log_sequence++);
+	lh->lh_flags = cpu_to_be32(flags);
+	lh->lh_tail = cpu_to_be32(tail);
+	lh->lh_blkno = cpu_to_be32(sdp->sd_log_flush_head);
+	hash = gfs2_disk_hash(page_address(page), sizeof(struct gfs2_log_header));
+	lh->lh_hash = cpu_to_be32(hash);
+
+	if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags)) {
+		gfs2_ordered_wait(sdp);
+		log_flush_wait(sdp);
+		rw = WRITE_SYNC | REQ_META | REQ_PRIO;
+	}
+
+	sdp->sd_log_idle = (tail == sdp->sd_log_flush_head);
+	gfs2_log_write_page(sdp, page);
+	gfs2_log_flush_bio(sdp, rw);
+	log_flush_wait(sdp);
+
+	if (sdp->sd_log_tail != tail)
+		log_pull_tail(sdp, tail);
+}
+
+/**
+ * gfs2_log_flush - flush incore transaction(s)
+ * @sdp: the filesystem
+ * @gl: The glock structure to flush.  If NULL, flush the whole incore log
+ *
+ */
+
+void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl,
+		    enum gfs2_flush_type type)
+{
+	struct gfs2_trans *tr;
+	enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);
+
+	down_write(&sdp->sd_log_flush_lock);
+
+	/* Log might have been flushed while we waited for the flush lock */
+	if (gl && !test_bit(GLF_LFLUSH, &gl->gl_flags)) {
+		up_write(&sdp->sd_log_flush_lock);
+		return;
+	}
+	trace_gfs2_log_flush(sdp, 1);
+
+	sdp->sd_log_flush_head = sdp->sd_log_head;
+	sdp->sd_log_flush_wrapped = 0;
+	tr = sdp->sd_log_tr;
+	if (tr) {
+		sdp->sd_log_tr = NULL;
+		INIT_LIST_HEAD(&tr->tr_ail1_list);
+		INIT_LIST_HEAD(&tr->tr_ail2_list);
+		tr->tr_first = sdp->sd_log_flush_head;
+		if (unlikely (state == SFS_FROZEN))
+			gfs2_assert_withdraw(sdp, !tr->tr_num_buf_new && !tr->tr_num_databuf_new);
+	}
+
+	if (unlikely(state == SFS_FROZEN))
+		gfs2_assert_withdraw(sdp, !sdp->sd_log_num_revoke);
+	gfs2_assert_withdraw(sdp,
+			sdp->sd_log_num_revoke == sdp->sd_log_commited_revoke);
+
+	gfs2_ordered_write(sdp);
+	lops_before_commit(sdp, tr);
+	gfs2_log_flush_bio(sdp, WRITE);
+
+	if (sdp->sd_log_head != sdp->sd_log_flush_head) {
+		log_flush_wait(sdp);
+		log_write_header(sdp, 0);
+	} else if (sdp->sd_log_tail != current_tail(sdp) && !sdp->sd_log_idle){
+		atomic_dec(&sdp->sd_log_blks_free); /* Adjust for unreserved buffer */
+		trace_gfs2_log_blocks(sdp, -1);
+		log_write_header(sdp, 0);
+	}
+	lops_after_commit(sdp, tr);
+
+	gfs2_log_lock(sdp);
+	sdp->sd_log_head = sdp->sd_log_flush_head;
+	sdp->sd_log_blks_reserved = 0;
+	sdp->sd_log_commited_revoke = 0;
+
+	spin_lock(&sdp->sd_ail_lock);
+	if (tr && !list_empty(&tr->tr_ail1_list)) {
+		list_add(&tr->tr_list, &sdp->sd_ail1_list);
+		tr = NULL;
+	}
+	spin_unlock(&sdp->sd_ail_lock);
+	gfs2_log_unlock(sdp);
+
+	if (type != NORMAL_FLUSH) {
+		if (!sdp->sd_log_idle) {
+			for (;;) {
+				gfs2_ail1_start(sdp);
+				gfs2_ail1_wait(sdp);
+				if (gfs2_ail1_empty(sdp))
+					break;
+			}
+			atomic_dec(&sdp->sd_log_blks_free); /* Adjust for unreserved buffer */
+			trace_gfs2_log_blocks(sdp, -1);
+			sdp->sd_log_flush_wrapped = 0;
+			log_write_header(sdp, 0);
+			sdp->sd_log_head = sdp->sd_log_flush_head;
+		}
+		if (type == SHUTDOWN_FLUSH || type == FREEZE_FLUSH)
+			gfs2_log_shutdown(sdp);
+		if (type == FREEZE_FLUSH)
+			atomic_set(&sdp->sd_freeze_state, SFS_FROZEN);
+	}
+
+	trace_gfs2_log_flush(sdp, 0);
+	up_write(&sdp->sd_log_flush_lock);
+
+	kfree(tr);
+}
+
+/**
+ * gfs2_merge_trans - Merge a new transaction into a cached transaction
+ * @old: Original transaction to be expanded
+ * @new: New transaction to be merged
+ */
+
+static void gfs2_merge_trans(struct gfs2_trans *old, struct gfs2_trans *new)
+{
+	WARN_ON_ONCE(old->tr_attached != 1);
+
+	old->tr_num_buf_new	+= new->tr_num_buf_new;
+	old->tr_num_databuf_new	+= new->tr_num_databuf_new;
+	old->tr_num_buf_rm	+= new->tr_num_buf_rm;
+	old->tr_num_databuf_rm	+= new->tr_num_databuf_rm;
+	old->tr_num_revoke	+= new->tr_num_revoke;
+	old->tr_num_revoke_rm	+= new->tr_num_revoke_rm;
+
+	list_splice_tail_init(&new->tr_databuf, &old->tr_databuf);
+	list_splice_tail_init(&new->tr_buf, &old->tr_buf);
+}
+
+static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
+{
+	unsigned int reserved;
+	unsigned int unused;
+	unsigned int maxres;
+
+	gfs2_log_lock(sdp);
+
+	if (sdp->sd_log_tr) {
+		gfs2_merge_trans(sdp->sd_log_tr, tr);
+	} else if (tr->tr_num_buf_new || tr->tr_num_databuf_new) {
+		gfs2_assert_withdraw(sdp, tr->tr_alloced);
+		sdp->sd_log_tr = tr;
+		tr->tr_attached = 1;
+	}
+
+	sdp->sd_log_commited_revoke += tr->tr_num_revoke - tr->tr_num_revoke_rm;
+	reserved = calc_reserved(sdp);
+	maxres = sdp->sd_log_blks_reserved + tr->tr_reserved;
+	gfs2_assert_withdraw(sdp, maxres >= reserved);
+	unused = maxres - reserved;
+	atomic_add(unused, &sdp->sd_log_blks_free);
+	trace_gfs2_log_blocks(sdp, unused);
+	gfs2_assert_withdraw(sdp, atomic_read(&sdp->sd_log_blks_free) <=
+			     sdp->sd_jdesc->jd_blocks);
+	sdp->sd_log_blks_reserved = reserved;
+
+	gfs2_log_unlock(sdp);
+}
+
+/**
+ * gfs2_log_commit - Commit a transaction to the log
+ * @sdp: the filesystem
+ * @tr: the transaction
+ *
+ * We wake up gfs2_logd if the number of pinned blocks exceed thresh1
+ * or the total number of used blocks (pinned blocks plus AIL blocks)
+ * is greater than thresh2.
+ *
+ * At mount time thresh1 is 1/3rd of journal size, thresh2 is 2/3rd of
+ * journal size.
+ *
+ * Returns: errno
+ */
+
+void gfs2_log_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
+{
+	log_refund(sdp, tr);
+
+	if (atomic_read(&sdp->sd_log_pinned) > atomic_read(&sdp->sd_log_thresh1) ||
+	    ((sdp->sd_jdesc->jd_blocks - atomic_read(&sdp->sd_log_blks_free)) >
+	    atomic_read(&sdp->sd_log_thresh2)))
+		wake_up(&sdp->sd_logd_waitq);
+}
+
+/**
+ * gfs2_log_shutdown - write a shutdown header into a journal
+ * @sdp: the filesystem
+ *
+ */
+
+void gfs2_log_shutdown(struct gfs2_sbd *sdp)
+{
+	gfs2_assert_withdraw(sdp, !sdp->sd_log_blks_reserved);
+	gfs2_assert_withdraw(sdp, !sdp->sd_log_num_revoke);
+	gfs2_assert_withdraw(sdp, list_empty(&sdp->sd_ail1_list));
+
+	sdp->sd_log_flush_head = sdp->sd_log_head;
+	sdp->sd_log_flush_wrapped = 0;
+
+	log_write_header(sdp, GFS2_LOG_HEAD_UNMOUNT);
+
+	gfs2_assert_warn(sdp, sdp->sd_log_head == sdp->sd_log_tail);
+	gfs2_assert_warn(sdp, list_empty(&sdp->sd_ail2_list));
+
+	sdp->sd_log_head = sdp->sd_log_flush_head;
+	sdp->sd_log_tail = sdp->sd_log_head;
+}
+
+static inline int gfs2_jrnl_flush_reqd(struct gfs2_sbd *sdp)
+{
+	return (atomic_read(&sdp->sd_log_pinned) >= atomic_read(&sdp->sd_log_thresh1));
+}
+
+static inline int gfs2_ail_flush_reqd(struct gfs2_sbd *sdp)
+{
+	unsigned int used_blocks = sdp->sd_jdesc->jd_blocks - atomic_read(&sdp->sd_log_blks_free);
+	return used_blocks >= atomic_read(&sdp->sd_log_thresh2);
+}
+
+/**
+ * gfs2_logd - Update log tail as Active Items get flushed to in-place blocks
+ * @sdp: Pointer to GFS2 superblock
+ *
+ * Also, periodically check to make sure that we're using the most recent
+ * journal index.
+ */
+
+int gfs2_logd(void *data)
+{
+	struct gfs2_sbd *sdp = data;
+	unsigned long t = 1;
+	DEFINE_WAIT(wait);
+
+	while (!kthread_should_stop()) {
+
+		if (gfs2_jrnl_flush_reqd(sdp) || t == 0) {
+			gfs2_ail1_empty(sdp);
+			gfs2_log_flush(sdp, NULL, NORMAL_FLUSH);
+		}
+
+		if (gfs2_ail_flush_reqd(sdp)) {
+			gfs2_ail1_start(sdp);
+			gfs2_ail1_wait(sdp);
+			gfs2_ail1_empty(sdp);
+			gfs2_log_flush(sdp, NULL, NORMAL_FLUSH);
+		}
+
+		if (!gfs2_ail_flush_reqd(sdp))
+			wake_up(&sdp->sd_log_waitq);
+
+		t = gfs2_tune_get(sdp, gt_logd_secs) * HZ;
+
+		try_to_freeze();
+
+		do {
+			prepare_to_wait(&sdp->sd_logd_waitq, &wait,
+					TASK_INTERRUPTIBLE);
+			if (!gfs2_ail_flush_reqd(sdp) &&
+			    !gfs2_jrnl_flush_reqd(sdp) &&
+			    !kthread_should_stop())
+				t = schedule_timeout(t);
+		} while(t && !gfs2_ail_flush_reqd(sdp) &&
+			!gfs2_jrnl_flush_reqd(sdp) &&
+			!kthread_should_stop());
+		finish_wait(&sdp->sd_logd_waitq, &wait);
+	}
+
+	return 0;
+}
+