Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1352 insertions, 0 deletions

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
new file mode 100644
index 000000000..e021d5f50
--- /dev/null
+++ b/fs/gfs2/log.c
@@ -0,0 +1,1352 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2007 Red Hat, Inc.  All rights reserved.
+ */
+
+#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/crc32c.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"
+#include "trans.h"
+
+static void gfs2_log_shutdown(struct gfs2_sbd *sdp);
+
+/**
+ * gfs2_struct2blk - compute stuff
+ * @sdp: the filesystem
+ * @nstruct: the number of 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 blks;
+	unsigned int first, second;
+
+	/* The initial struct gfs2_log_descriptor block */
+	blks = 1;
+	first = sdp->sd_ldptrs;
+
+	if (nstruct > first) {
+		/* Subsequent struct gfs2_meta_header blocks */
+		second = sdp->sd_inptrs;
+		blks += DIV_ROUND_UP(nstruct - first, second);
+	}
+
+	return blks;
+}
+
+/**
+ * gfs2_remove_from_ail - Remove an entry from the ail lists, updating counters
+ * @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);
+}
+
+static int __gfs2_writepage(struct page *page, struct writeback_control *wbc,
+		       void *data)
+{
+	struct address_space *mapping = data;
+	int ret = mapping->a_ops->writepage(page, wbc);
+	mapping_set_error(mapping, ret);
+	return ret;
+}
+
+/**
+ * gfs2_ail1_start_one - Start I/O on a transaction
+ * @sdp: The superblock
+ * @wbc: The writeback control structure
+ * @tr: The transaction to start I/O on
+ * @plug: The block plug currently active
+ */
+
+static int gfs2_ail1_start_one(struct gfs2_sbd *sdp,
+			       struct writeback_control *wbc,
+			       struct gfs2_trans *tr, struct blk_plug *plug)
+__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;
+	int ret = 0;
+
+	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)) {
+				list_move(&bd->bd_ail_st_list,
+					  &tr->tr_ail2_list);
+				continue;
+			}
+			if (!cmpxchg(&sdp->sd_log_error, 0, -EIO)) {
+				gfs2_io_error_bh(sdp, bh);
+				gfs2_withdraw_delayed(sdp);
+			}
+		}
+
+		if (gfs2_withdrawn(sdp)) {
+			gfs2_remove_from_ail(bd);
+			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);
+		ret = write_cache_pages(mapping, wbc, __gfs2_writepage, mapping);
+		if (need_resched()) {
+			blk_finish_plug(plug);
+			cond_resched();
+			blk_start_plug(plug);
+		}
+		spin_lock(&sdp->sd_ail_lock);
+		if (ret == -ENODATA) /* if a jdata write into a new hole */
+			ret = 0; /* ignore it */
+		if (ret || wbc->nr_to_write <= 0)
+			break;
+		return -EBUSY;
+	}
+
+	return ret;
+}
+
+static void dump_ail_list(struct gfs2_sbd *sdp)
+{
+	struct gfs2_trans *tr;
+	struct gfs2_bufdata *bd;
+	struct buffer_head *bh;
+
+	list_for_each_entry_reverse(tr, &sdp->sd_ail1_list, tr_list) {
+		list_for_each_entry_reverse(bd, &tr->tr_ail1_list,
+					    bd_ail_st_list) {
+			bh = bd->bd_bh;
+			fs_err(sdp, "bd %p: blk:0x%llx bh=%p ", bd,
+			       (unsigned long long)bd->bd_blkno, bh);
+			if (!bh) {
+				fs_err(sdp, "\n");
+				continue;
+			}
+			fs_err(sdp, "0x%llx up2:%d dirt:%d lkd:%d req:%d "
+			       "map:%d new:%d ar:%d aw:%d delay:%d "
+			       "io err:%d unwritten:%d dfr:%d pin:%d esc:%d\n",
+			       (unsigned long long)bh->b_blocknr,
+			       buffer_uptodate(bh), buffer_dirty(bh),
+			       buffer_locked(bh), buffer_req(bh),
+			       buffer_mapped(bh), buffer_new(bh),
+			       buffer_async_read(bh), buffer_async_write(bh),
+			       buffer_delay(bh), buffer_write_io_error(bh),
+			       buffer_unwritten(bh),
+			       buffer_defer_completion(bh),
+			       buffer_pinned(bh), buffer_escaped(bh));
+		}
+	}
+}
+
+/**
+ * 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;
+	int ret;
+	unsigned long flush_start = jiffies;
+
+	trace_gfs2_ail_flush(sdp, wbc, 1);
+	blk_start_plug(&plug);
+	spin_lock(&sdp->sd_ail_lock);
+restart:
+	ret = 0;
+	if (time_after(jiffies, flush_start + (HZ * 600))) {
+		fs_err(sdp, "Error: In %s for ten minutes! t=%d\n",
+		       __func__, current->journal_info ? 1 : 0);
+		dump_ail_list(sdp);
+		goto out;
+	}
+	list_for_each_entry_reverse(tr, head, tr_list) {
+		if (wbc->nr_to_write <= 0)
+			break;
+		ret = gfs2_ail1_start_one(sdp, wbc, tr, &plug);
+		if (ret) {
+			if (ret == -EBUSY)
+				goto restart;
+			break;
+		}
+	}
+out:
+	spin_unlock(&sdp->sd_ail_lock);
+	blk_finish_plug(&plug);
+	if (ret) {
+		gfs2_lm(sdp, "gfs2_ail1_start_one returned: %d\n", ret);
+		gfs2_withdraw(sdp);
+	}
+	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);
+}
+
+static void gfs2_log_update_flush_tail(struct gfs2_sbd *sdp)
+{
+	unsigned int new_flush_tail = sdp->sd_log_head;
+	struct gfs2_trans *tr;
+
+	if (!list_empty(&sdp->sd_ail1_list)) {
+		tr = list_last_entry(&sdp->sd_ail1_list,
+				     struct gfs2_trans, tr_list);
+		new_flush_tail = tr->tr_first;
+	}
+	sdp->sd_log_flush_tail = new_flush_tail;
+}
+
+static void gfs2_log_update_head(struct gfs2_sbd *sdp)
+{
+	unsigned int new_head = sdp->sd_log_flush_head;
+
+	if (sdp->sd_log_flush_tail == sdp->sd_log_head)
+		sdp->sd_log_flush_tail = new_head;
+	sdp->sd_log_head = new_head;
+}
+
+/*
+ * gfs2_ail_empty_tr - empty one of the ail lists of a transaction
+ */
+
+static void gfs2_ail_empty_tr(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
+			      struct list_head *head)
+{
+	struct gfs2_bufdata *bd;
+
+	while (!list_empty(head)) {
+		bd = list_first_entry(head, struct gfs2_bufdata,
+				      bd_ail_st_list);
+		gfs2_assert(sdp, bd->bd_tr == tr);
+		gfs2_remove_from_ail(bd);
+	}
+}
+
+/**
+ * gfs2_ail1_empty_one - Check whether or not a trans in the AIL has been synced
+ * @sdp: the filesystem
+ * @tr: the transaction
+ * @max_revokes: If nonzero, issue revokes for the bd items for written buffers
+ *
+ * returns: the transaction's count of remaining active items
+ */
+
+static int gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
+				int *max_revokes)
+{
+	struct gfs2_bufdata *bd, *s;
+	struct buffer_head *bh;
+	int active_count = 0;
+
+	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 another process flagged an io error, e.g. writing to the
+		 * journal, error all other bhs and move them off the ail1 to
+		 * prevent a tight loop when unmount tries to flush ail1,
+		 * regardless of whether they're still busy. If no outside
+		 * errors were found and the buffer is busy, move to the next.
+		 * If the ail buffer is not busy and caught an error, flag it
+		 * for others.
+		 */
+		if (!sdp->sd_log_error && buffer_busy(bh)) {
+			active_count++;
+			continue;
+		}
+		if (!buffer_uptodate(bh) &&
+		    !cmpxchg(&sdp->sd_log_error, 0, -EIO)) {
+			gfs2_io_error_bh(sdp, bh);
+			gfs2_withdraw_delayed(sdp);
+		}
+		/*
+		 * If we have space for revokes and the bd is no longer on any
+		 * buf list, we can just add a revoke for it immediately and
+		 * avoid having to put it on the ail2 list, where it would need
+		 * to be revoked later.
+		 */
+		if (*max_revokes && list_empty(&bd->bd_list)) {
+			gfs2_add_revoke(sdp, bd);
+			(*max_revokes)--;
+			continue;
+		}
+		list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
+	}
+	return active_count;
+}
+
+/**
+ * gfs2_ail1_empty - Try to empty the ail1 lists
+ * @sdp: The superblock
+ * @max_revokes: If non-zero, add revokes where appropriate
+ *
+ * Tries to empty the ail1 lists, starting with the oldest first
+ */
+
+static int gfs2_ail1_empty(struct gfs2_sbd *sdp, int max_revokes)
+{
+	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) {
+		if (!gfs2_ail1_empty_one(sdp, tr, &max_revokes) && oldest_tr)
+			list_move(&tr->tr_list, &sdp->sd_ail2_list);
+		else
+			oldest_tr = 0;
+	}
+	gfs2_log_update_flush_tail(sdp);
+	ret = list_empty(&sdp->sd_ail1_list);
+	spin_unlock(&sdp->sd_ail_lock);
+
+	if (test_bit(SDF_WITHDRAWING, &sdp->sd_flags)) {
+		gfs2_lm(sdp, "fatal: I/O error(s)\n");
+		gfs2_withdraw(sdp);
+	}
+
+	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);
+}
+
+static void __ail2_empty(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
+{
+	gfs2_ail_empty_tr(sdp, tr, &tr->tr_ail2_list);
+	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));
+	gfs2_trans_free(sdp, tr);
+}
+
+static void ail2_empty(struct gfs2_sbd *sdp, unsigned int new_tail)
+{
+	struct list_head *ail2_list = &sdp->sd_ail2_list;
+	unsigned int old_tail = sdp->sd_log_tail;
+	struct gfs2_trans *tr, *safe;
+
+	spin_lock(&sdp->sd_ail_lock);
+	if (old_tail <= new_tail) {
+		list_for_each_entry_safe(tr, safe, ail2_list, tr_list) {
+			if (old_tail <= tr->tr_first && tr->tr_first < new_tail)
+				__ail2_empty(sdp, tr);
+		}
+	} else {
+		list_for_each_entry_safe(tr, safe, ail2_list, tr_list) {
+			if (old_tail <= tr->tr_first || tr->tr_first < new_tail)
+				__ail2_empty(sdp, tr);
+		}
+	}
+	spin_unlock(&sdp->sd_ail_lock);
+}
+
+/**
+ * gfs2_log_is_empty - Check if the log is empty
+ * @sdp: The GFS2 superblock
+ */
+
+bool gfs2_log_is_empty(struct gfs2_sbd *sdp) {
+	return atomic_read(&sdp->sd_log_blks_free) == sdp->sd_jdesc->jd_blocks;
+}
+
+static bool __gfs2_log_try_reserve_revokes(struct gfs2_sbd *sdp, unsigned int revokes)
+{
+	unsigned int available;
+
+	available = atomic_read(&sdp->sd_log_revokes_available);
+	while (available >= revokes) {
+		if (atomic_try_cmpxchg(&sdp->sd_log_revokes_available,
+				       &available, available - revokes))
+			return true;
+	}
+	return false;
+}
+
+/**
+ * gfs2_log_release_revokes - Release a given number of revokes
+ * @sdp: The GFS2 superblock
+ * @revokes: The number of revokes to release
+ *
+ * sdp->sd_log_flush_lock must be held.
+ */
+void gfs2_log_release_revokes(struct gfs2_sbd *sdp, unsigned int revokes)
+{
+	if (revokes)
+		atomic_add(revokes, &sdp->sd_log_revokes_available);
+}
+
+/**
+ * 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);
+	if (atomic_read(&sdp->sd_log_blks_needed))
+		wake_up(&sdp->sd_log_waitq);
+}
+
+/**
+ * __gfs2_log_try_reserve - Try to make a log reservation
+ * @sdp: The GFS2 superblock
+ * @blks: The number of blocks to reserve
+ * @taboo_blks: The number of blocks to leave free
+ *
+ * Try to do the same as __gfs2_log_reserve(), but fail if no more log
+ * space is immediately available.
+ */
+static bool __gfs2_log_try_reserve(struct gfs2_sbd *sdp, unsigned int blks,
+				   unsigned int taboo_blks)
+{
+	unsigned wanted = blks + taboo_blks;
+	unsigned int free_blocks;
+
+	free_blocks = atomic_read(&sdp->sd_log_blks_free);
+	while (free_blocks >= wanted) {
+		if (atomic_try_cmpxchg(&sdp->sd_log_blks_free, &free_blocks,
+				       free_blocks - blks)) {
+			trace_gfs2_log_blocks(sdp, -blks);
+			return true;
+		}
+	}
+	return false;
+}
+
+/**
+ * __gfs2_log_reserve - Make a log reservation
+ * @sdp: The GFS2 superblock
+ * @blks: The number of blocks to reserve
+ * @taboo_blks: The number of blocks to leave free
+ *
+ * @taboo_blks is set to 0 for logd, and to GFS2_LOG_FLUSH_MIN_BLOCKS
+ * for all other processes.  This ensures that when the log is almost full,
+ * logd will still be able to call gfs2_log_flush one more time  without
+ * blocking, which will advance the tail and make some more log space
+ * available.
+ *
+ * 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.
+ */
+
+static void __gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks,
+			       unsigned int taboo_blks)
+{
+	unsigned wanted = blks + taboo_blks;
+	unsigned int free_blocks;
+
+	atomic_add(blks, &sdp->sd_log_blks_needed);
+	for (;;) {
+		if (current != sdp->sd_logd_process)
+			wake_up(&sdp->sd_logd_waitq);
+		io_wait_event(sdp->sd_log_waitq,
+			(free_blocks = atomic_read(&sdp->sd_log_blks_free),
+			 free_blocks >= wanted));
+		do {
+			if (atomic_try_cmpxchg(&sdp->sd_log_blks_free,
+					       &free_blocks,
+					       free_blocks - blks))
+				goto reserved;
+		} while (free_blocks >= wanted);
+	}
+
+reserved:
+	trace_gfs2_log_blocks(sdp, -blks);
+	if (atomic_sub_return(blks, &sdp->sd_log_blks_needed))
+		wake_up(&sdp->sd_log_waitq);
+}
+
+/**
+ * gfs2_log_try_reserve - Try to make a log reservation
+ * @sdp: The GFS2 superblock
+ * @tr: The transaction
+ * @extra_revokes: The number of additional revokes reserved (output)
+ *
+ * This is similar to gfs2_log_reserve, but sdp->sd_log_flush_lock must be
+ * held for correct revoke accounting.
+ */
+
+bool gfs2_log_try_reserve(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
+			  unsigned int *extra_revokes)
+{
+	unsigned int blks = tr->tr_reserved;
+	unsigned int revokes = tr->tr_revokes;
+	unsigned int revoke_blks = 0;
+
+	*extra_revokes = 0;
+	if (revokes && !__gfs2_log_try_reserve_revokes(sdp, revokes)) {
+		revoke_blks = DIV_ROUND_UP(revokes, sdp->sd_inptrs);
+		*extra_revokes = revoke_blks * sdp->sd_inptrs - revokes;
+		blks += revoke_blks;
+	}
+	if (!blks)
+		return true;
+	if (__gfs2_log_try_reserve(sdp, blks, GFS2_LOG_FLUSH_MIN_BLOCKS))
+		return true;
+	if (!revoke_blks)
+		gfs2_log_release_revokes(sdp, revokes);
+	return false;
+}
+
+/**
+ * gfs2_log_reserve - Make a log reservation
+ * @sdp: The GFS2 superblock
+ * @tr: The transaction
+ * @extra_revokes: The number of additional revokes reserved (output)
+ *
+ * sdp->sd_log_flush_lock must not be held.
+ */
+
+void gfs2_log_reserve(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
+		      unsigned int *extra_revokes)
+{
+	unsigned int blks = tr->tr_reserved;
+	unsigned int revokes = tr->tr_revokes;
+	unsigned int revoke_blks;
+
+	*extra_revokes = 0;
+	if (revokes) {
+		revoke_blks = DIV_ROUND_UP(revokes, sdp->sd_inptrs);
+		*extra_revokes = revoke_blks * sdp->sd_inptrs - revokes;
+		blks += revoke_blks;
+	}
+	__gfs2_log_reserve(sdp, blks, GFS2_LOG_FLUSH_MIN_BLOCKS);
+}
+
+/**
+ * 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 keep reserved
+ * @sdp: The GFS2 superblock
+ *
+ * This is complex.  We need to reserve room for all our currently used
+ * metadata blocks (e.g. normal file I/O rewriting file time stamps) and
+ * all our journaled data blocks 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, corruption will follow.
+ *
+ * We can have metadata blocks and jdata blocks in the same journal.  Each
+ * type gets its own log descriptor, for which we need to reserve a block.
+ * In fact, each type has the potential for needing more than one log descriptor
+ * in cases where we have more blocks than will fit in a log descriptor.
+ * Metadata journal entries take up half the space of journaled buffer entries.
+ *
+ * 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 = GFS2_LOG_FLUSH_MIN_BLOCKS;
+	unsigned int blocks;
+	struct gfs2_trans *tr = sdp->sd_log_tr;
+
+	if (tr) {
+		blocks = tr->tr_num_buf_new - tr->tr_num_buf_rm;
+		reserved += blocks + DIV_ROUND_UP(blocks, buf_limit(sdp));
+		blocks = tr->tr_num_databuf_new - tr->tr_num_databuf_rm;
+		reserved += blocks + DIV_ROUND_UP(blocks, databuf_limit(sdp));
+	}
+	return reserved;
+}
+
+static void log_pull_tail(struct gfs2_sbd *sdp)
+{
+	unsigned int new_tail = sdp->sd_log_flush_tail;
+	unsigned int dist;
+
+	if (new_tail == sdp->sd_log_tail)
+		return;
+	dist = log_distance(sdp, new_tail, sdp->sd_log_tail);
+	ail2_empty(sdp, new_tail);
+	gfs2_log_release(sdp, dist);
+	sdp->sd_log_tail = new_tail;
+}
+
+
+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, const struct list_head *a, const 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 __ordered_del_inode(struct gfs2_inode *ip)
+{
+	if (!list_empty(&ip->i_ordered))
+		list_del_init(&ip->i_ordered);
+}
+
+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_ordered, &ip_cmp);
+	while (!list_empty(&sdp->sd_log_ordered)) {
+		ip = list_first_entry(&sdp->sd_log_ordered, struct gfs2_inode, i_ordered);
+		if (ip->i_inode.i_mapping->nrpages == 0) {
+			__ordered_del_inode(ip);
+			continue;
+		}
+		list_move(&ip->i_ordered, &written);
+		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_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_ordered)) {
+		ip = list_first_entry(&sdp->sd_log_ordered, struct gfs2_inode, i_ordered);
+		__ordered_del_inode(ip);
+		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);
+	__ordered_del_inode(ip);
+	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;
+
+	sdp->sd_log_num_revoke++;
+	if (atomic_inc_return(&gl->gl_revokes) == 1)
+		gfs2_glock_hold(gl);
+	bh->b_private = NULL;
+	bd->bd_blkno = bh->b_blocknr;
+	gfs2_remove_from_ail(bd); /* drops ref on bh */
+	bd->bd_bh = NULL;
+	set_bit(GLF_LFLUSH, &gl->gl_flags);
+	list_add(&bd->bd_list, &sdp->sd_log_revokes);
+}
+
+void gfs2_glock_remove_revoke(struct gfs2_glock *gl)
+{
+	if (atomic_dec_return(&gl->gl_revokes) == 0) {
+		clear_bit(GLF_LFLUSH, &gl->gl_flags);
+		gfs2_glock_queue_put(gl);
+	}
+}
+
+/**
+ * gfs2_flush_revokes - Add as many revokes to the system transaction as we can
+ * @sdp: The GFS2 superblock
+ *
+ * Our usual strategy is to defer writing revokes as much as we can in the hope
+ * that we'll eventually overwrite the journal, which will make those revokes
+ * go away.  This changes when we flush the log: at that point, there will
+ * likely be some left-over space in the last revoke block of that transaction.
+ * We can fill that space with additional revokes for blocks that have already
+ * been written back.  This will basically come at no cost now, and will save
+ * us from having to keep track of those blocks on the AIL2 list later.
+ */
+void gfs2_flush_revokes(struct gfs2_sbd *sdp)
+{
+	/* number of revokes we still have room for */
+	unsigned int max_revokes = atomic_read(&sdp->sd_log_revokes_available);
+
+	gfs2_log_lock(sdp);
+	gfs2_ail1_empty(sdp, max_revokes);
+	gfs2_log_unlock(sdp);
+}
+
+/**
+ * gfs2_write_log_header - Write a journal log header buffer at lblock
+ * @sdp: The GFS2 superblock
+ * @jd: journal descriptor of the journal to which we are writing
+ * @seq: sequence number
+ * @tail: tail of the log
+ * @lblock: value for lh_blkno (block number relative to start of journal)
+ * @flags: log header flags GFS2_LOG_HEAD_*
+ * @op_flags: flags to pass to the bio
+ *
+ * Returns: the initialized log buffer descriptor
+ */
+
+void gfs2_write_log_header(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd,
+			   u64 seq, u32 tail, u32 lblock, u32 flags,
+			   blk_opf_t op_flags)
+{
+	struct gfs2_log_header *lh;
+	u32 hash, crc;
+	struct page *page;
+	struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
+	struct timespec64 tv;
+	struct super_block *sb = sdp->sd_vfs;
+	u64 dblock;
+
+	if (gfs2_withdrawn(sdp))
+		return;
+
+	page = mempool_alloc(gfs2_page_pool, GFP_NOIO);
+	lh = page_address(page);
+	clear_page(lh);
+
+	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(seq);
+	lh->lh_flags = cpu_to_be32(flags);
+	lh->lh_tail = cpu_to_be32(tail);
+	lh->lh_blkno = cpu_to_be32(lblock);
+	hash = ~crc32(~0, lh, LH_V1_SIZE);
+	lh->lh_hash = cpu_to_be32(hash);
+
+	ktime_get_coarse_real_ts64(&tv);
+	lh->lh_nsec = cpu_to_be32(tv.tv_nsec);
+	lh->lh_sec = cpu_to_be64(tv.tv_sec);
+	if (!list_empty(&jd->extent_list))
+		dblock = gfs2_log_bmap(jd, lblock);
+	else {
+		unsigned int extlen;
+		int ret;
+
+		extlen = 1;
+		ret = gfs2_get_extent(jd->jd_inode, lblock, &dblock, &extlen);
+		if (gfs2_assert_withdraw(sdp, ret == 0))
+			return;
+	}
+	lh->lh_addr = cpu_to_be64(dblock);
+	lh->lh_jinode = cpu_to_be64(GFS2_I(jd->jd_inode)->i_no_addr);
+
+	/* We may only write local statfs, quota, etc., when writing to our
+	   own journal. The values are left 0 when recovering a journal
+	   different from our own. */
+	if (!(flags & GFS2_LOG_HEAD_RECOVERY)) {
+		lh->lh_statfs_addr =
+			cpu_to_be64(GFS2_I(sdp->sd_sc_inode)->i_no_addr);
+		lh->lh_quota_addr =
+			cpu_to_be64(GFS2_I(sdp->sd_qc_inode)->i_no_addr);
+
+		spin_lock(&sdp->sd_statfs_spin);
+		lh->lh_local_total = cpu_to_be64(l_sc->sc_total);
+		lh->lh_local_free = cpu_to_be64(l_sc->sc_free);
+		lh->lh_local_dinodes = cpu_to_be64(l_sc->sc_dinodes);
+		spin_unlock(&sdp->sd_statfs_spin);
+	}
+
+	BUILD_BUG_ON(offsetof(struct gfs2_log_header, lh_crc) != LH_V1_SIZE);
+
+	crc = crc32c(~0, (void *)lh + LH_V1_SIZE + 4,
+		     sb->s_blocksize - LH_V1_SIZE - 4);
+	lh->lh_crc = cpu_to_be32(crc);
+
+	gfs2_log_write(sdp, jd, page, sb->s_blocksize, 0, dblock);
+	gfs2_log_submit_bio(&jd->jd_log_bio, REQ_OP_WRITE | op_flags);
+}
+
+/**
+ * log_write_header - Get and initialize a journal header buffer
+ * @sdp: The GFS2 superblock
+ * @flags: The log header flags, including log header origin
+ *
+ * Returns: the initialized log buffer descriptor
+ */
+
+static void log_write_header(struct gfs2_sbd *sdp, u32 flags)
+{
+	blk_opf_t op_flags = REQ_PREFLUSH | REQ_FUA | REQ_META | REQ_SYNC;
+	enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);
+
+	gfs2_assert_withdraw(sdp, (state != SFS_FROZEN));
+
+	if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags)) {
+		gfs2_ordered_wait(sdp);
+		log_flush_wait(sdp);
+		op_flags = REQ_SYNC | REQ_META | REQ_PRIO;
+	}
+	sdp->sd_log_idle = (sdp->sd_log_flush_tail == sdp->sd_log_flush_head);
+	gfs2_write_log_header(sdp, sdp->sd_jdesc, sdp->sd_log_sequence++,
+			      sdp->sd_log_flush_tail, sdp->sd_log_flush_head,
+			      flags, op_flags);
+	gfs2_log_incr_head(sdp);
+	log_flush_wait(sdp);
+	log_pull_tail(sdp);
+	gfs2_log_update_head(sdp);
+}
+
+/**
+ * gfs2_ail_drain - drain the ail lists after a withdraw
+ * @sdp: Pointer to GFS2 superblock
+ */
+void gfs2_ail_drain(struct gfs2_sbd *sdp)
+{
+	struct gfs2_trans *tr;
+
+	spin_lock(&sdp->sd_ail_lock);
+	/*
+	 * For transactions on the sd_ail1_list we need to drain both the
+	 * ail1 and ail2 lists. That's because function gfs2_ail1_start_one
+	 * (temporarily) moves items from its tr_ail1 list to tr_ail2 list
+	 * before revokes are sent for that block. Items on the sd_ail2_list
+	 * should have already gotten beyond that point, so no need.
+	 */
+	while (!list_empty(&sdp->sd_ail1_list)) {
+		tr = list_first_entry(&sdp->sd_ail1_list, struct gfs2_trans,
+				      tr_list);
+		gfs2_ail_empty_tr(sdp, tr, &tr->tr_ail1_list);
+		gfs2_ail_empty_tr(sdp, tr, &tr->tr_ail2_list);
+		list_del(&tr->tr_list);
+		gfs2_trans_free(sdp, tr);
+	}
+	while (!list_empty(&sdp->sd_ail2_list)) {
+		tr = list_first_entry(&sdp->sd_ail2_list, struct gfs2_trans,
+				      tr_list);
+		gfs2_ail_empty_tr(sdp, tr, &tr->tr_ail2_list);
+		list_del(&tr->tr_list);
+		gfs2_trans_free(sdp, tr);
+	}
+	gfs2_drain_revokes(sdp);
+	spin_unlock(&sdp->sd_ail_lock);
+}
+
+/**
+ * empty_ail1_list - try to start IO and empty the ail1 list
+ * @sdp: Pointer to GFS2 superblock
+ */
+static void empty_ail1_list(struct gfs2_sbd *sdp)
+{
+	unsigned long start = jiffies;
+
+	for (;;) {
+		if (time_after(jiffies, start + (HZ * 600))) {
+			fs_err(sdp, "Error: In %s for 10 minutes! t=%d\n",
+			       __func__, current->journal_info ? 1 : 0);
+			dump_ail_list(sdp);
+			return;
+		}
+		gfs2_ail1_start(sdp);
+		gfs2_ail1_wait(sdp);
+		if (gfs2_ail1_empty(sdp, 0))
+			return;
+	}
+}
+
+/**
+ * trans_drain - drain the buf and databuf queue for a failed transaction
+ * @tr: the transaction to drain
+ *
+ * When this is called, we're taking an error exit for a log write that failed
+ * but since we bypassed the after_commit functions, we need to remove the
+ * items from the buf and databuf queue.
+ */
+static void trans_drain(struct gfs2_trans *tr)
+{
+	struct gfs2_bufdata *bd;
+	struct list_head *head;
+
+	if (!tr)
+		return;
+
+	head = &tr->tr_buf;
+	while (!list_empty(head)) {
+		bd = list_first_entry(head, struct gfs2_bufdata, bd_list);
+		list_del_init(&bd->bd_list);
+		if (!list_empty(&bd->bd_ail_st_list))
+			gfs2_remove_from_ail(bd);
+		kmem_cache_free(gfs2_bufdata_cachep, bd);
+	}
+	head = &tr->tr_databuf;
+	while (!list_empty(head)) {
+		bd = list_first_entry(head, struct gfs2_bufdata, bd_list);
+		list_del_init(&bd->bd_list);
+		if (!list_empty(&bd->bd_ail_st_list))
+			gfs2_remove_from_ail(bd);
+		kmem_cache_free(gfs2_bufdata_cachep, bd);
+	}
+}
+
+/**
+ * gfs2_log_flush - flush incore transaction(s)
+ * @sdp: The filesystem
+ * @gl: The glock structure to flush.  If NULL, flush the whole incore log
+ * @flags: The log header flags: GFS2_LOG_HEAD_FLUSH_* and debug flags
+ *
+ */
+
+void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags)
+{
+	struct gfs2_trans *tr = NULL;
+	unsigned int reserved_blocks = 0, used_blocks = 0;
+	enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);
+	unsigned int first_log_head;
+	unsigned int reserved_revokes = 0;
+
+	down_write(&sdp->sd_log_flush_lock);
+	trace_gfs2_log_flush(sdp, 1, flags);
+
+repeat:
+	/*
+	 * Do this check while holding the log_flush_lock to prevent new
+	 * buffers from being added to the ail via gfs2_pin()
+	 */
+	if (gfs2_withdrawn(sdp) || !test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
+		goto out;
+
+	/* Log might have been flushed while we waited for the flush lock */
+	if (gl && !test_bit(GLF_LFLUSH, &gl->gl_flags))
+		goto out;
+
+	first_log_head = sdp->sd_log_head;
+	sdp->sd_log_flush_head = first_log_head;
+
+	tr = sdp->sd_log_tr;
+	if (tr || sdp->sd_log_num_revoke) {
+		if (reserved_blocks)
+			gfs2_log_release(sdp, reserved_blocks);
+		reserved_blocks = sdp->sd_log_blks_reserved;
+		reserved_revokes = sdp->sd_log_num_revoke;
+		if (tr) {
+			sdp->sd_log_tr = NULL;
+			tr->tr_first = first_log_head;
+			if (unlikely (state == SFS_FROZEN)) {
+				if (gfs2_assert_withdraw_delayed(sdp,
+				       !tr->tr_num_buf_new && !tr->tr_num_databuf_new))
+					goto out_withdraw;
+			}
+		}
+	} else if (!reserved_blocks) {
+		unsigned int taboo_blocks = GFS2_LOG_FLUSH_MIN_BLOCKS;
+
+		reserved_blocks = GFS2_LOG_FLUSH_MIN_BLOCKS;
+		if (current == sdp->sd_logd_process)
+			taboo_blocks = 0;
+
+		if (!__gfs2_log_try_reserve(sdp, reserved_blocks, taboo_blocks)) {
+			up_write(&sdp->sd_log_flush_lock);
+			__gfs2_log_reserve(sdp, reserved_blocks, taboo_blocks);
+			down_write(&sdp->sd_log_flush_lock);
+			goto repeat;
+		}
+		BUG_ON(sdp->sd_log_num_revoke);
+	}
+
+	if (flags & GFS2_LOG_HEAD_FLUSH_SHUTDOWN)
+		clear_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
+
+	if (unlikely(state == SFS_FROZEN))
+		if (gfs2_assert_withdraw_delayed(sdp, !reserved_revokes))
+			goto out_withdraw;
+
+	gfs2_ordered_write(sdp);
+	if (gfs2_withdrawn(sdp))
+		goto out_withdraw;
+	lops_before_commit(sdp, tr);
+	if (gfs2_withdrawn(sdp))
+		goto out_withdraw;
+	gfs2_log_submit_bio(&sdp->sd_jdesc->jd_log_bio, REQ_OP_WRITE);
+	if (gfs2_withdrawn(sdp))
+		goto out_withdraw;
+
+	if (sdp->sd_log_head != sdp->sd_log_flush_head) {
+		log_write_header(sdp, flags);
+	} else if (sdp->sd_log_tail != sdp->sd_log_flush_tail && !sdp->sd_log_idle) {
+		log_write_header(sdp, flags);
+	}
+	if (gfs2_withdrawn(sdp))
+		goto out_withdraw;
+	lops_after_commit(sdp, tr);
+
+	gfs2_log_lock(sdp);
+	sdp->sd_log_blks_reserved = 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 (!(flags & GFS2_LOG_HEAD_FLUSH_NORMAL)) {
+		if (!sdp->sd_log_idle) {
+			empty_ail1_list(sdp);
+			if (gfs2_withdrawn(sdp))
+				goto out_withdraw;
+			log_write_header(sdp, flags);
+		}
+		if (flags & (GFS2_LOG_HEAD_FLUSH_SHUTDOWN |
+			     GFS2_LOG_HEAD_FLUSH_FREEZE))
+			gfs2_log_shutdown(sdp);
+		if (flags & GFS2_LOG_HEAD_FLUSH_FREEZE)
+			atomic_set(&sdp->sd_freeze_state, SFS_FROZEN);
+	}
+
+out_end:
+	used_blocks = log_distance(sdp, sdp->sd_log_flush_head, first_log_head);
+	reserved_revokes += atomic_read(&sdp->sd_log_revokes_available);
+	atomic_set(&sdp->sd_log_revokes_available, sdp->sd_ldptrs);
+	gfs2_assert_withdraw(sdp, reserved_revokes % sdp->sd_inptrs == sdp->sd_ldptrs);
+	if (reserved_revokes > sdp->sd_ldptrs)
+		reserved_blocks += (reserved_revokes - sdp->sd_ldptrs) / sdp->sd_inptrs;
+out:
+	if (used_blocks != reserved_blocks) {
+		gfs2_assert_withdraw_delayed(sdp, used_blocks < reserved_blocks);
+		gfs2_log_release(sdp, reserved_blocks - used_blocks);
+	}
+	up_write(&sdp->sd_log_flush_lock);
+	gfs2_trans_free(sdp, tr);
+	if (gfs2_withdrawing(sdp))
+		gfs2_withdraw(sdp);
+	trace_gfs2_log_flush(sdp, 0, flags);
+	return;
+
+out_withdraw:
+	trans_drain(tr);
+	/**
+	 * If the tr_list is empty, we're withdrawing during a log
+	 * flush that targets a transaction, but the transaction was
+	 * never queued onto any of the ail lists. Here we add it to
+	 * ail1 just so that ail_drain() will find and free it.
+	 */
+	spin_lock(&sdp->sd_ail_lock);
+	if (tr && list_empty(&tr->tr_list))
+		list_add(&tr->tr_list, &sdp->sd_ail1_list);
+	spin_unlock(&sdp->sd_ail_lock);
+	tr = NULL;
+	goto out_end;
+}
+
+/**
+ * gfs2_merge_trans - Merge a new transaction into a cached transaction
+ * @sdp: the filesystem
+ * @new: New transaction to be merged
+ */
+
+static void gfs2_merge_trans(struct gfs2_sbd *sdp, struct gfs2_trans *new)
+{
+	struct gfs2_trans *old = sdp->sd_log_tr;
+
+	WARN_ON_ONCE(!test_bit(TR_ATTACHED, &old->tr_flags));
+
+	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_revokes		+= new->tr_revokes;
+	old->tr_num_revoke	+= new->tr_num_revoke;
+
+	list_splice_tail_init(&new->tr_databuf, &old->tr_databuf);
+	list_splice_tail_init(&new->tr_buf, &old->tr_buf);
+
+	spin_lock(&sdp->sd_ail_lock);
+	list_splice_tail_init(&new->tr_ail1_list, &old->tr_ail1_list);
+	list_splice_tail_init(&new->tr_ail2_list, &old->tr_ail2_list);
+	spin_unlock(&sdp->sd_ail_lock);
+}
+
+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, tr);
+	} else if (tr->tr_num_buf_new || tr->tr_num_databuf_new) {
+		gfs2_assert_withdraw(sdp, !test_bit(TR_ONSTACK, &tr->tr_flags));
+		sdp->sd_log_tr = tr;
+		set_bit(TR_ATTACHED, &tr->tr_flags);
+	}
+
+	reserved = calc_reserved(sdp);
+	maxres = sdp->sd_log_blks_reserved + tr->tr_reserved;
+	gfs2_assert_withdraw(sdp, maxres >= reserved);
+	unused = maxres - reserved;
+	if (unused)
+		gfs2_log_release(sdp, unused);
+	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 2/5ths of journal size, thresh2 is 4/5ths 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
+ *
+ */
+
+static 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));
+
+	log_write_header(sdp, GFS2_LOG_HEAD_UNMOUNT | GFS2_LFC_SHUTDOWN);
+	log_pull_tail(sdp);
+
+	gfs2_assert_warn(sdp, sdp->sd_log_head == sdp->sd_log_tail);
+	gfs2_assert_warn(sdp, list_empty(&sdp->sd_ail2_list));
+}
+
+static inline int gfs2_jrnl_flush_reqd(struct gfs2_sbd *sdp)
+{
+	return (atomic_read(&sdp->sd_log_pinned) +
+		atomic_read(&sdp->sd_log_blks_needed) >=
+		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_blks_needed) >=
+		atomic_read(&sdp->sd_log_thresh2);
+}
+
+/**
+ * gfs2_logd - Update log tail as Active Items get flushed to in-place blocks
+ * @data: 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;
+
+	while (!kthread_should_stop()) {
+
+		if (gfs2_withdrawn(sdp)) {
+			msleep_interruptible(HZ);
+			continue;
+		}
+		/* Check for errors writing to the journal */
+		if (sdp->sd_log_error) {
+			gfs2_lm(sdp,
+				"GFS2: fsid=%s: error %d: "
+				"withdrawing the file system to "
+				"prevent further damage.\n",
+				sdp->sd_fsname, sdp->sd_log_error);
+			gfs2_withdraw(sdp);
+			continue;
+		}
+
+		if (gfs2_jrnl_flush_reqd(sdp) || t == 0) {
+			gfs2_ail1_empty(sdp, 0);
+			gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_NORMAL |
+						  GFS2_LFC_LOGD_JFLUSH_REQD);
+		}
+
+		if (test_bit(SDF_FORCE_AIL_FLUSH, &sdp->sd_flags) ||
+		    gfs2_ail_flush_reqd(sdp)) {
+			clear_bit(SDF_FORCE_AIL_FLUSH, &sdp->sd_flags);
+			gfs2_ail1_start(sdp);
+			gfs2_ail1_wait(sdp);
+			gfs2_ail1_empty(sdp, 0);
+			gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_NORMAL |
+						  GFS2_LFC_LOGD_AIL_FLUSH_REQD);
+		}
+
+		t = gfs2_tune_get(sdp, gt_logd_secs) * HZ;
+
+		try_to_freeze();
+
+		t = wait_event_interruptible_timeout(sdp->sd_logd_waitq,
+				test_bit(SDF_FORCE_AIL_FLUSH, &sdp->sd_flags) ||
+				gfs2_ail_flush_reqd(sdp) ||
+				gfs2_jrnl_flush_reqd(sdp) ||
+				kthread_should_stop(),
+				t);
+	}
+
+	return 0;
+}
+