// 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;
  
  	blks = 1;

  	first = sdp->sd_ldptrs;

  
  	if (nstruct > first) {

  		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
   * @mapping: The associated mapping (maybe NULL)
   * @bd: The gfs2_bufdata to remove
   *

   * The ail lock _must_ be held when calling this function

   *
   */

  static 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;

  	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 = generic_writepages(mapping, wbc);

  		spin_lock(&sdp->sd_ail_lock);

  		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, "
  ");
  				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
  ",
  			       (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
  ",
  		       __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);
  		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 (generic_writepages) "
  			"returned: %d
  ", 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);

  }
  
  /**
   * 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

   *
   */

  static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
  				int *max_revokes)

  {
  	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 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))

  			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);

  	}

  }

  /**
   * 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) {

  		gfs2_ail1_empty_one(sdp, tr, &max_revokes);

  		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);

  	if (test_bit(SDF_WITHDRAWING, &sdp->sd_flags)) {

  		gfs2_lm(sdp, "fatal: I/O error(s)
  ");
  		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);
  }

  
  /**

   * gfs2_ail_empty_tr - empty one of the ail lists for 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);

  	}
  }

  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_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);

  	}

  	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;

  	atomic_add(blks, &sdp->sd_log_blks_needed);

  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;

  	}

  	atomic_sub(blks, &sdp->sd_log_blks_needed);

  	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_committed_revoke > 0)
  		reserved += gfs2_struct2blk(sdp, sdp->sd_log_committed_revoke);

  	/* 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_last_entry(&sdp->sd_ail1_list, 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;
  }

  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 __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_write_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_write_revokes(struct gfs2_sbd *sdp)
  {

  	/* number of revokes we still have room for */

  	int max_revokes = (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_log_descriptor)) / sizeof(u64);

  	gfs2_log_lock(sdp);

  	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_ail1_empty(sdp, max_revokes);

  	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);
  	}
  }

  /**

   * 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,
  			   int 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))
  		goto out;
  
  	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 {
  		int ret = gfs2_lblk_to_dblk(jd->jd_inode, lblock, &dblock);
  		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, page, sb->s_blocksize, 0, dblock);

  	gfs2_log_submit_bio(&sdp->sd_log_bio, REQ_OP_WRITE | op_flags);

  out:

  	log_flush_wait(sdp);
  }
  
  /**
   * 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)
  {
  	unsigned int tail;
  	int 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));
  	tail = current_tail(sdp);

  	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 = (tail == sdp->sd_log_flush_head);

  	gfs2_write_log_header(sdp, sdp->sd_jdesc, sdp->sd_log_sequence++, tail,

  			      sdp->sd_log_flush_head, flags, op_flags);

  	gfs2_log_incr_head(sdp);

  
  	if (sdp->sd_log_tail != tail)
  		log_pull_tail(sdp, tail);

  }
  
  /**

   * ail_drain - drain the ail lists after a withdraw
   * @sdp: Pointer to GFS2 superblock
   */
  static void 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);

  	}
  	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
  ",
  			       __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;
  	}
  }
  
  /**

   * 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;

  	enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);

  	down_write(&sdp->sd_log_flush_lock);

  	/*
  	 * 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))
  		goto out;

  	/* 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, flags);

  	if (flags & GFS2_LOG_HEAD_FLUSH_SHUTDOWN)

  		clear_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);

  	sdp->sd_log_flush_head = sdp->sd_log_head;

  	tr = sdp->sd_log_tr;
  	if (tr) {
  		sdp->sd_log_tr = NULL;

  		tr->tr_first = sdp->sd_log_flush_head;

  		if (unlikely (state == SFS_FROZEN))

  			if (gfs2_assert_withdraw_delayed(sdp,
  			       !tr->tr_num_buf_new && !tr->tr_num_databuf_new))
  				goto out;

  	}

  	if (unlikely(state == SFS_FROZEN))

  		if (gfs2_assert_withdraw_delayed(sdp, !sdp->sd_log_num_revoke))
  			goto out;
  	if (gfs2_assert_withdraw_delayed(sdp,
  			sdp->sd_log_num_revoke == sdp->sd_log_committed_revoke))
  		goto out;

  	gfs2_ordered_write(sdp);

  	if (gfs2_withdrawn(sdp))
  		goto out;

  	lops_before_commit(sdp, tr);

  	if (gfs2_withdrawn(sdp))
  		goto out;

  	gfs2_log_submit_bio(&sdp->sd_log_bio, REQ_OP_WRITE);

  	if (gfs2_withdrawn(sdp))
  		goto out;

  	if (sdp->sd_log_head != sdp->sd_log_flush_head) {

  		log_flush_wait(sdp);

  		log_write_header(sdp, flags);

  	} 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, flags);

  	}

  	if (gfs2_withdrawn(sdp))
  		goto out;

  	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_committed_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 (!(flags & GFS2_LOG_HEAD_FLUSH_NORMAL)) {

  		if (!sdp->sd_log_idle) {

  			empty_ail1_list(sdp);

  			if (gfs2_withdrawn(sdp))
  				goto out;

  			atomic_dec(&sdp->sd_log_blks_free); /* Adjust for unreserved buffer */
  			trace_gfs2_log_blocks(sdp, -1);

  			log_write_header(sdp, flags);

  			sdp->sd_log_head = sdp->sd_log_flush_head;
  		}

  		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:

  	if (gfs2_withdrawn(sdp)) {

  		/**
  		 * 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);

  		ail_drain(sdp); /* frees all transactions */
  		tr = NULL;
  	}

  	trace_gfs2_log_flush(sdp, 0, flags);

  	up_write(&sdp->sd_log_flush_lock);

  	gfs2_trans_free(sdp, 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_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_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);

  
  	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_ALLOCED, &tr->tr_flags));

  		sdp->sd_log_tr = tr;

  		set_bit(TR_ATTACHED, &tr->tr_flags);

  	}

  	sdp->sd_log_committed_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
   *
   */

  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));
  
  	sdp->sd_log_flush_head = sdp->sd_log_head;

  	log_write_header(sdp, GFS2_LOG_HEAD_UNMOUNT | GFS2_LFC_SHUTDOWN);

  	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_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);

  
  	if (test_and_clear_bit(SDF_FORCE_AIL_FLUSH, &sdp->sd_flags))
  		return 1;

  	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
   * @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);

  	bool did_flush;

  
  	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.
  ",
  				sdp->sd_fsname, sdp->sd_log_error);
  			gfs2_withdraw(sdp);

  			continue;

  		}

  		did_flush = false;

  		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);

  			did_flush = true;

  		}

  		if (gfs2_ail_flush_reqd(sdp)) {
  			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);

  			did_flush = true;

  		}

  		if (!gfs2_ail_flush_reqd(sdp) || did_flush)

  			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;
  }