// SPDX-License-Identifier: GPL-2.0

  /*

   * Copyright (c) 2000-2005 Silicon Graphics, Inc.
   * All Rights Reserved.

   */

  #include "xfs.h"

  #include "xfs_fs.h"

  #include "xfs_shared.h"

  #include "xfs_format.h"

  #include "xfs_log_format.h"
  #include "xfs_trans_resv.h"

  #include "xfs_bit.h"

  #include "xfs_mount.h"

  #include "xfs_trans.h"

  #include "xfs_trans_priv.h"

  #include "xfs_buf_item.h"

  #include "xfs_inode.h"
  #include "xfs_inode_item.h"

  #include "xfs_quota.h"
  #include "xfs_dquot_item.h"
  #include "xfs_dquot.h"

  #include "xfs_trace.h"

  #include "xfs_log.h"

  
  
  kmem_zone_t	*xfs_buf_item_zone;

  static inline struct xfs_buf_log_item *BUF_ITEM(struct xfs_log_item *lip)
  {
  	return container_of(lip, struct xfs_buf_log_item, bli_item);
  }

  /* Is this log iovec plausibly large enough to contain the buffer log format? */
  bool
  xfs_buf_log_check_iovec(
  	struct xfs_log_iovec		*iovec)
  {
  	struct xfs_buf_log_format	*blfp = iovec->i_addr;
  	char				*bmp_end;
  	char				*item_end;
  
  	if (offsetof(struct xfs_buf_log_format, blf_data_map) > iovec->i_len)
  		return false;
  
  	item_end = (char *)iovec->i_addr + iovec->i_len;
  	bmp_end = (char *)&blfp->blf_data_map[blfp->blf_map_size];
  	return bmp_end <= item_end;
  }

  static inline int
  xfs_buf_log_format_size(
  	struct xfs_buf_log_format *blfp)
  {
  	return offsetof(struct xfs_buf_log_format, blf_data_map) +
  			(blfp->blf_map_size * sizeof(blfp->blf_data_map[0]));
  }

  /*
   * This returns the number of log iovecs needed to log the
   * given buf log item.
   *
   * It calculates this as 1 iovec for the buf log format structure
   * and 1 for each stretch of non-contiguous chunks to be logged.
   * Contiguous chunks are logged in a single iovec.
   *
   * If the XFS_BLI_STALE flag has been set, then log nothing.
   */

  STATIC void

  xfs_buf_item_size_segment(

  	struct xfs_buf_log_item		*bip,
  	struct xfs_buf_log_format	*blfp,
  	int				*nvecs,
  	int				*nbytes)

  {

  	struct xfs_buf			*bp = bip->bli_buf;
  	int				next_bit;
  	int				last_bit;

  	last_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);
  	if (last_bit == -1)

  		return;

  
  	/*
  	 * initial count for a dirty buffer is 2 vectors - the format structure
  	 * and the first dirty region.
  	 */

  	*nvecs += 2;
  	*nbytes += xfs_buf_log_format_size(blfp) + XFS_BLF_CHUNK;

  	while (last_bit != -1) {
  		/*
  		 * This takes the bit number to start looking from and
  		 * returns the next set bit from there.  It returns -1
  		 * if there are no more bits set or the start bit is
  		 * beyond the end of the bitmap.
  		 */

  		next_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size,
  					last_bit + 1);

  		/*
  		 * If we run out of bits, leave the loop,
  		 * else if we find a new set of bits bump the number of vecs,
  		 * else keep scanning the current set of bits.
  		 */
  		if (next_bit == -1) {

  			break;

  		} else if (next_bit != last_bit + 1) {
  			last_bit = next_bit;

  			(*nvecs)++;

  		} else if (xfs_buf_offset(bp, next_bit * XFS_BLF_CHUNK) !=
  			   (xfs_buf_offset(bp, last_bit * XFS_BLF_CHUNK) +
  			    XFS_BLF_CHUNK)) {

  			last_bit = next_bit;

  			(*nvecs)++;

  		} else {
  			last_bit++;
  		}

  		*nbytes += XFS_BLF_CHUNK;

  	}

  }
  
  /*

   * This returns the number of log iovecs needed to log the given buf log item.
   *
   * It calculates this as 1 iovec for the buf log format structure and 1 for each
   * stretch of non-contiguous chunks to be logged.  Contiguous chunks are logged
   * in a single iovec.
   *

   * Discontiguous buffers need a format structure per region that is being

   * logged. This makes the changes in the buffer appear to log recovery as though
   * they came from separate buffers, just like would occur if multiple buffers
   * were used instead of a single discontiguous buffer. This enables
   * discontiguous buffers to be in-memory constructs, completely transparent to
   * what ends up on disk.
   *
   * If the XFS_BLI_STALE flag has been set, then log nothing but the buf log
   * format structures.

   */

  STATIC void

  xfs_buf_item_size(

  	struct xfs_log_item	*lip,
  	int			*nvecs,
  	int			*nbytes)

  {

  	struct xfs_buf_log_item	*bip = BUF_ITEM(lip);

  	int			i;
  
  	ASSERT(atomic_read(&bip->bli_refcount) > 0);
  	if (bip->bli_flags & XFS_BLI_STALE) {
  		/*
  		 * The buffer is stale, so all we need to log
  		 * is the buf log format structure with the
  		 * cancel flag in it.
  		 */
  		trace_xfs_buf_item_size_stale(bip);

  		ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);

  		*nvecs += bip->bli_format_count;
  		for (i = 0; i < bip->bli_format_count; i++) {
  			*nbytes += xfs_buf_log_format_size(&bip->bli_formats[i]);
  		}
  		return;

  	}
  
  	ASSERT(bip->bli_flags & XFS_BLI_LOGGED);

  	if (bip->bli_flags & XFS_BLI_ORDERED) {
  		/*
  		 * The buffer has been logged just to order it.
  		 * It is not being included in the transaction
  		 * commit, so no vectors are used at all.
  		 */
  		trace_xfs_buf_item_size_ordered(bip);

  		*nvecs = XFS_LOG_VEC_ORDERED;
  		return;

  	}

  	/*
  	 * the vector count is based on the number of buffer vectors we have
  	 * dirty bits in. This will only be greater than one when we have a
  	 * compound buffer with more than one segment dirty. Hence for compound
  	 * buffers we need to track which segment the dirty bits correspond to,
  	 * and when we move from one segment to the next increment the vector
  	 * count for the extra buf log format structure that will need to be
  	 * written.
  	 */

  	for (i = 0; i < bip->bli_format_count; i++) {

  		xfs_buf_item_size_segment(bip, &bip->bli_formats[i],
  					  nvecs, nbytes);

  	}

  	trace_xfs_buf_item_size(bip);

  }

  static inline void

  xfs_buf_item_copy_iovec(

  	struct xfs_log_vec	*lv,

  	struct xfs_log_iovec	**vecp,

  	struct xfs_buf		*bp,
  	uint			offset,
  	int			first_bit,
  	uint			nbits)
  {
  	offset += first_bit * XFS_BLF_CHUNK;

  	xlog_copy_iovec(lv, vecp, XLOG_REG_TYPE_BCHUNK,

  			xfs_buf_offset(bp, offset),
  			nbits * XFS_BLF_CHUNK);

  }
  
  static inline bool
  xfs_buf_item_straddle(
  	struct xfs_buf		*bp,
  	uint			offset,
  	int			next_bit,
  	int			last_bit)
  {
  	return xfs_buf_offset(bp, offset + (next_bit << XFS_BLF_SHIFT)) !=
  		(xfs_buf_offset(bp, offset + (last_bit << XFS_BLF_SHIFT)) +
  		 XFS_BLF_CHUNK);
  }

  static void

  xfs_buf_item_format_segment(
  	struct xfs_buf_log_item	*bip,

  	struct xfs_log_vec	*lv,

  	struct xfs_log_iovec	**vecp,

  	uint			offset,
  	struct xfs_buf_log_format *blfp)
  {

  	struct xfs_buf		*bp = bip->bli_buf;
  	uint			base_size;
  	int			first_bit;
  	int			last_bit;
  	int			next_bit;
  	uint			nbits;

  	/* copy the flags across from the base format item */

  	blfp->blf_flags = bip->__bli_format.blf_flags;

  
  	/*

  	 * Base size is the actual size of the ondisk structure - it reflects
  	 * the actual size of the dirty bitmap rather than the size of the in
  	 * memory structure.

  	 */

  	base_size = xfs_buf_log_format_size(blfp);

  	first_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);
  	if (!(bip->bli_flags & XFS_BLI_STALE) && first_bit == -1) {
  		/*
  		 * If the map is not be dirty in the transaction, mark
  		 * the size as zero and do not advance the vector pointer.
  		 */

  		return;

  	}

  	blfp = xlog_copy_iovec(lv, vecp, XLOG_REG_TYPE_BFORMAT, blfp, base_size);
  	blfp->blf_size = 1;

  
  	if (bip->bli_flags & XFS_BLI_STALE) {
  		/*
  		 * The buffer is stale, so all we need to log
  		 * is the buf log format structure with the
  		 * cancel flag in it.
  		 */

  		trace_xfs_buf_item_format_stale(bip);

  		ASSERT(blfp->blf_flags & XFS_BLF_CANCEL);

  		return;

  	}

  	/*
  	 * Fill in an iovec for each set of contiguous chunks.
  	 */

  	last_bit = first_bit;
  	nbits = 1;
  	for (;;) {
  		/*
  		 * This takes the bit number to start looking from and
  		 * returns the next set bit from there.  It returns -1
  		 * if there are no more bits set or the start bit is
  		 * beyond the end of the bitmap.
  		 */

  		next_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size,
  					(uint)last_bit + 1);

  		/*

  		 * If we run out of bits fill in the last iovec and get out of
  		 * the loop.  Else if we start a new set of bits then fill in
  		 * the iovec for the series we were looking at and start
  		 * counting the bits in the new one.  Else we're still in the
  		 * same set of bits so just keep counting and scanning.

  		 */
  		if (next_bit == -1) {

  			xfs_buf_item_copy_iovec(lv, vecp, bp, offset,

  						first_bit, nbits);

  			blfp->blf_size++;

  			break;

  		} else if (next_bit != last_bit + 1 ||
  		           xfs_buf_item_straddle(bp, offset, next_bit, last_bit)) {

  			xfs_buf_item_copy_iovec(lv, vecp, bp, offset,

  						first_bit, nbits);

  			blfp->blf_size++;

  			first_bit = next_bit;
  			last_bit = next_bit;
  			nbits = 1;
  		} else {
  			last_bit++;
  			nbits++;
  		}
  	}

  }
  
  /*
   * This is called to fill in the vector of log iovecs for the
   * given log buf item.  It fills the first entry with a buf log
   * format structure, and the rest point to contiguous chunks
   * within the buffer.
   */
  STATIC void
  xfs_buf_item_format(
  	struct xfs_log_item	*lip,

  	struct xfs_log_vec	*lv)

  {
  	struct xfs_buf_log_item	*bip = BUF_ITEM(lip);
  	struct xfs_buf		*bp = bip->bli_buf;

  	struct xfs_log_iovec	*vecp = NULL;

  	uint			offset = 0;
  	int			i;
  
  	ASSERT(atomic_read(&bip->bli_refcount) > 0);
  	ASSERT((bip->bli_flags & XFS_BLI_LOGGED) ||
  	       (bip->bli_flags & XFS_BLI_STALE));

  	ASSERT((bip->bli_flags & XFS_BLI_STALE) ||
  	       (xfs_blft_from_flags(&bip->__bli_format) > XFS_BLFT_UNKNOWN_BUF
  	        && xfs_blft_from_flags(&bip->__bli_format) < XFS_BLFT_MAX_BUF));

  	ASSERT(!(bip->bli_flags & XFS_BLI_ORDERED) ||
  	       (bip->bli_flags & XFS_BLI_STALE));

  
  	/*
  	 * If it is an inode buffer, transfer the in-memory state to the

  	 * format flags and clear the in-memory state.
  	 *
  	 * For buffer based inode allocation, we do not transfer

  	 * this state if the inode buffer allocation has not yet been committed
  	 * to the log as setting the XFS_BLI_INODE_BUF flag will prevent
  	 * correct replay of the inode allocation.

  	 *
  	 * For icreate item based inode allocation, the buffers aren't written
  	 * to the journal during allocation, and hence we should always tag the
  	 * buffer as an inode buffer so that the correct unlinked list replay
  	 * occurs during recovery.

  	 */
  	if (bip->bli_flags & XFS_BLI_INODE_BUF) {

  		if (xfs_sb_version_has_v3inode(&lip->li_mountp->m_sb) ||

  		    !((bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF) &&

  		      xfs_log_item_in_current_chkpt(lip)))

  			bip->__bli_format.blf_flags |= XFS_BLF_INODE_BUF;

  		bip->bli_flags &= ~XFS_BLI_INODE_BUF;
  	}
  
  	for (i = 0; i < bip->bli_format_count; i++) {

  		xfs_buf_item_format_segment(bip, lv, &vecp, offset,

  					    &bip->bli_formats[i]);

  		offset += BBTOB(bp->b_maps[i].bm_len);

  	}

  
  	/*
  	 * Check to make sure everything is consistent.
  	 */

  	trace_xfs_buf_item_format(bip);

  }
  
  /*

   * This is called to pin the buffer associated with the buf log item in memory

   * so it cannot be written out.

   *
   * We also always take a reference to the buffer log item here so that the bli
   * is held while the item is pinned in memory. This means that we can
   * unconditionally drop the reference count a transaction holds when the
   * transaction is completed.

   */

  STATIC void

  xfs_buf_item_pin(

  	struct xfs_log_item	*lip)

  {

  	struct xfs_buf_log_item	*bip = BUF_ITEM(lip);

  	ASSERT(atomic_read(&bip->bli_refcount) > 0);
  	ASSERT((bip->bli_flags & XFS_BLI_LOGGED) ||

  	       (bip->bli_flags & XFS_BLI_ORDERED) ||

  	       (bip->bli_flags & XFS_BLI_STALE));

  	trace_xfs_buf_item_pin(bip);

  
  	atomic_inc(&bip->bli_refcount);
  	atomic_inc(&bip->bli_buf->b_pin_count);

  }

  /*
   * This is called to unpin the buffer associated with the buf log
   * item which was previously pinned with a call to xfs_buf_item_pin().

   *
   * Also drop the reference to the buf item for the current transaction.
   * If the XFS_BLI_STALE flag is set and we are the last reference,
   * then free up the buf log item and unlock the buffer.

   *
   * If the remove flag is set we are called from uncommit in the
   * forced-shutdown path.  If that is true and the reference count on
   * the log item is going to drop to zero we need to free the item's
   * descriptor in the transaction.

   */

  STATIC void

  xfs_buf_item_unpin(

  	struct xfs_log_item	*lip,

  	int			remove)

  {

  	struct xfs_buf_log_item	*bip = BUF_ITEM(lip);

  	xfs_buf_t		*bp = bip->bli_buf;

  	int			stale = bip->bli_flags & XFS_BLI_STALE;
  	int			freed;

  	ASSERT(bp->b_log_item == bip);

  	ASSERT(atomic_read(&bip->bli_refcount) > 0);

  	trace_xfs_buf_item_unpin(bip);

  
  	freed = atomic_dec_and_test(&bip->bli_refcount);

  
  	if (atomic_dec_and_test(&bp->b_pin_count))
  		wake_up_all(&bp->b_waiters);

  	if (freed && stale) {
  		ASSERT(bip->bli_flags & XFS_BLI_STALE);

  		ASSERT(xfs_buf_islocked(bp));

  		ASSERT(bp->b_flags & XBF_STALE);

  		ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);

  		trace_xfs_buf_item_unpin_stale(bip);

  		if (remove) {
  			/*

  			 * If we are in a transaction context, we have to
  			 * remove the log item from the transaction as we are
  			 * about to release our reference to the buffer.  If we
  			 * don't, the unlock that occurs later in
  			 * xfs_trans_uncommit() will try to reference the

  			 * buffer which we no longer have a hold on.
  			 */

  			if (!list_empty(&lip->li_trans))

  				xfs_trans_del_item(lip);

  
  			/*
  			 * Since the transaction no longer refers to the buffer,
  			 * the buffer should no longer refer to the transaction.
  			 */

  			bp->b_transp = NULL;

  		}

  		/*

  		 * If we get called here because of an IO error, we may or may
  		 * not have the item on the AIL. xfs_trans_ail_delete() will
  		 * take care of that situation. xfs_trans_ail_delete() drops
  		 * the AIL lock.

  		 */
  		if (bip->bli_flags & XFS_BLI_STALE_INODE) {

  			xfs_buf_item_done(bp);

  			xfs_buf_inode_iodone(bp);

  			ASSERT(list_empty(&bp->b_li_list));

  		} else {

  			xfs_trans_ail_delete(lip, SHUTDOWN_LOG_IO_ERROR);

  			xfs_buf_item_relse(bp);

  			ASSERT(bp->b_log_item == NULL);

  		}
  		xfs_buf_relse(bp);

  	} else if (freed && remove) {

  		/*

  		 * The buffer must be locked and held by the caller to simulate
  		 * an async I/O failure.

  		 */

  		xfs_buf_lock(bp);

  		xfs_buf_hold(bp);
  		bp->b_flags |= XBF_ASYNC;

  		xfs_buf_ioend_fail(bp);

  	}
  }

  STATIC uint

  xfs_buf_item_push(
  	struct xfs_log_item	*lip,
  	struct list_head	*buffer_list)

  {

  	struct xfs_buf_log_item	*bip = BUF_ITEM(lip);
  	struct xfs_buf		*bp = bip->bli_buf;

  	uint			rval = XFS_ITEM_SUCCESS;

  	if (xfs_buf_ispinned(bp))

  		return XFS_ITEM_PINNED;

  	if (!xfs_buf_trylock(bp)) {
  		/*
  		 * If we have just raced with a buffer being pinned and it has
  		 * been marked stale, we could end up stalling until someone else
  		 * issues a log force to unpin the stale buffer. Check for the
  		 * race condition here so xfsaild recognizes the buffer is pinned
  		 * and queues a log force to move it along.
  		 */
  		if (xfs_buf_ispinned(bp))
  			return XFS_ITEM_PINNED;

  		return XFS_ITEM_LOCKED;

  	}

  	ASSERT(!(bip->bli_flags & XFS_BLI_STALE));

  
  	trace_xfs_buf_item_push(bip);

  	/* has a previous flush failed due to IO errors? */

  	if (bp->b_flags & XBF_WRITE_FAIL) {
  		xfs_buf_alert_ratelimited(bp, "XFS: Failing async write",
  	    "Failing async write on buffer block 0x%llx. Retrying async write.",
  					  (long long)bp->b_bn);

  	}

  	if (!xfs_buf_delwri_queue(bp, buffer_list))
  		rval = XFS_ITEM_FLUSHING;
  	xfs_buf_unlock(bp);
  	return rval;

  }
  
  /*

   * Drop the buffer log item refcount and take appropriate action. This helper
   * determines whether the bli must be freed or not, since a decrement to zero
   * does not necessarily mean the bli is unused.
   *
   * Return true if the bli is freed, false otherwise.
   */
  bool
  xfs_buf_item_put(
  	struct xfs_buf_log_item	*bip)
  {
  	struct xfs_log_item	*lip = &bip->bli_item;
  	bool			aborted;
  	bool			dirty;
  
  	/* drop the bli ref and return if it wasn't the last one */
  	if (!atomic_dec_and_test(&bip->bli_refcount))
  		return false;
  
  	/*
  	 * We dropped the last ref and must free the item if clean or aborted.
  	 * If the bli is dirty and non-aborted, the buffer was clean in the
  	 * transaction but still awaiting writeback from previous changes. In
  	 * that case, the bli is freed on buffer writeback completion.
  	 */
  	aborted = test_bit(XFS_LI_ABORTED, &lip->li_flags) ||
  		  XFS_FORCED_SHUTDOWN(lip->li_mountp);
  	dirty = bip->bli_flags & XFS_BLI_DIRTY;
  	if (dirty && !aborted)
  		return false;
  
  	/*
  	 * The bli is aborted or clean. An aborted item may be in the AIL
  	 * regardless of dirty state.  For example, consider an aborted
  	 * transaction that invalidated a dirty bli and cleared the dirty
  	 * state.
  	 */
  	if (aborted)

  		xfs_trans_ail_delete(lip, 0);

  	xfs_buf_item_relse(bip->bli_buf);
  	return true;
  }
  
  /*

   * Release the buffer associated with the buf log item.  If there is no dirty
   * logged data associated with the buffer recorded in the buf log item, then
   * free the buf log item and remove the reference to it in the buffer.

   *

   * This call ignores the recursion count.  It is only called when the buffer
   * should REALLY be unlocked, regardless of the recursion count.

   *

   * We unconditionally drop the transaction's reference to the log item. If the
   * item was logged, then another reference was taken when it was pinned, so we
   * can safely drop the transaction reference now.  This also allows us to avoid
   * potential races with the unpin code freeing the bli by not referencing the
   * bli after we've dropped the reference count.
   *
   * If the XFS_BLI_HOLD flag is set in the buf log item, then free the log item
   * if necessary but do not unlock the buffer.  This is for support of
   * xfs_trans_bhold(). Make sure the XFS_BLI_HOLD field is cleared if we don't
   * free the item.

   */

  STATIC void

  xfs_buf_item_release(

  	struct xfs_log_item	*lip)

  {

  	struct xfs_buf_log_item	*bip = BUF_ITEM(lip);
  	struct xfs_buf		*bp = bip->bli_buf;

  	bool			released;

  	bool			hold = bip->bli_flags & XFS_BLI_HOLD;

  	bool			stale = bip->bli_flags & XFS_BLI_STALE;

  #if defined(DEBUG) || defined(XFS_WARN)

  	bool			ordered = bip->bli_flags & XFS_BLI_ORDERED;

  	bool			dirty = bip->bli_flags & XFS_BLI_DIRTY;

  	bool			aborted = test_bit(XFS_LI_ABORTED,
  						   &lip->li_flags);

  #endif

  	trace_xfs_buf_item_release(bip);

  
  	/*

  	 * The bli dirty state should match whether the blf has logged segments
  	 * except for ordered buffers, where only the bli should be dirty.

  	 */

  	ASSERT((!ordered && dirty == xfs_buf_item_dirty_format(bip)) ||
  	       (ordered && dirty && !xfs_buf_item_dirty_format(bip)));

  	ASSERT(!stale || (bip->__bli_format.blf_flags & XFS_BLF_CANCEL));

  	/*

  	 * Clear the buffer's association with this transaction and
  	 * per-transaction state from the bli, which has been copied above.
  	 */
  	bp->b_transp = NULL;
  	bip->bli_flags &= ~(XFS_BLI_LOGGED | XFS_BLI_HOLD | XFS_BLI_ORDERED);
  
  	/*

  	 * Unref the item and unlock the buffer unless held or stale. Stale
  	 * buffers remain locked until final unpin unless the bli is freed by
  	 * the unref call. The latter implies shutdown because buffer
  	 * invalidation dirties the bli and transaction.

  	 */

  	released = xfs_buf_item_put(bip);
  	if (hold || (stale && !released))

  		return;

  	ASSERT(!stale || aborted);

  	xfs_buf_relse(bp);

  }

  STATIC void
  xfs_buf_item_committing(
  	struct xfs_log_item	*lip,
  	xfs_lsn_t		commit_lsn)
  {
  	return xfs_buf_item_release(lip);
  }

  /*
   * This is called to find out where the oldest active copy of the
   * buf log item in the on disk log resides now that the last log
   * write of it completed at the given lsn.
   * We always re-log all the dirty data in a buffer, so usually the
   * latest copy in the on disk log is the only one that matters.  For
   * those cases we simply return the given lsn.
   *
   * The one exception to this is for buffers full of newly allocated
   * inodes.  These buffers are only relogged with the XFS_BLI_INODE_BUF
   * flag set, indicating that only the di_next_unlinked fields from the
   * inodes in the buffers will be replayed during recovery.  If the
   * original newly allocated inode images have not yet been flushed
   * when the buffer is so relogged, then we need to make sure that we
   * keep the old images in the 'active' portion of the log.  We do this
   * by returning the original lsn of that transaction here rather than
   * the current one.
   */

  STATIC xfs_lsn_t

  xfs_buf_item_committed(

  	struct xfs_log_item	*lip,

  	xfs_lsn_t		lsn)
  {

  	struct xfs_buf_log_item	*bip = BUF_ITEM(lip);

  	trace_xfs_buf_item_committed(bip);

  	if ((bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF) && lip->li_lsn != 0)
  		return lip->li_lsn;
  	return lsn;

  }

  static const struct xfs_item_ops xfs_buf_item_ops = {

  	.iop_size	= xfs_buf_item_size,
  	.iop_format	= xfs_buf_item_format,
  	.iop_pin	= xfs_buf_item_pin,
  	.iop_unpin	= xfs_buf_item_unpin,

  	.iop_release	= xfs_buf_item_release,
  	.iop_committing	= xfs_buf_item_committing,

  	.iop_committed	= xfs_buf_item_committed,
  	.iop_push	= xfs_buf_item_push,

  };

  STATIC void

  xfs_buf_item_get_format(
  	struct xfs_buf_log_item	*bip,
  	int			count)
  {
  	ASSERT(bip->bli_formats == NULL);
  	bip->bli_format_count = count;
  
  	if (count == 1) {

  		bip->bli_formats = &bip->__bli_format;

  		return;

  	}
  
  	bip->bli_formats = kmem_zalloc(count * sizeof(struct xfs_buf_log_format),

  				0);

  }
  
  STATIC void
  xfs_buf_item_free_format(
  	struct xfs_buf_log_item	*bip)
  {

  	if (bip->bli_formats != &bip->__bli_format) {

  		kmem_free(bip->bli_formats);
  		bip->bli_formats = NULL;
  	}
  }

  
  /*
   * Allocate a new buf log item to go with the given buffer.

   * Set the buffer's b_log_item field to point to the new
   * buf log item.

   */

  int

  xfs_buf_item_init(

  	struct xfs_buf	*bp,
  	struct xfs_mount *mp)

  {

  	struct xfs_buf_log_item	*bip = bp->b_log_item;

  	int			chunks;
  	int			map_size;

  	int			i;

  
  	/*
  	 * Check to see if there is already a buf log item for

  	 * this buffer. If we do already have one, there is

  	 * nothing to do here so return.
  	 */

  	ASSERT(bp->b_mount == mp);

  	if (bip) {

  		ASSERT(bip->bli_item.li_type == XFS_LI_BUF);

  		ASSERT(!bp->b_transp);
  		ASSERT(bip->bli_buf == bp);

  		return 0;

  	}

  	bip = kmem_cache_zalloc(xfs_buf_item_zone, GFP_KERNEL | __GFP_NOFAIL);

  	xfs_log_item_init(mp, &bip->bli_item, XFS_LI_BUF, &xfs_buf_item_ops);

  	bip->bli_buf = bp;

  
  	/*
  	 * chunks is the number of XFS_BLF_CHUNK size pieces the buffer
  	 * can be divided into. Make sure not to truncate any pieces.
  	 * map_size is the size of the bitmap needed to describe the
  	 * chunks of the buffer.
  	 *
  	 * Discontiguous buffer support follows the layout of the underlying
  	 * buffer. This makes the implementation as simple as possible.
  	 */

  	xfs_buf_item_get_format(bip, bp->b_map_count);

  
  	for (i = 0; i < bip->bli_format_count; i++) {
  		chunks = DIV_ROUND_UP(BBTOB(bp->b_maps[i].bm_len),
  				      XFS_BLF_CHUNK);
  		map_size = DIV_ROUND_UP(chunks, NBWORD);

  		if (map_size > XFS_BLF_DATAMAP_SIZE) {
  			kmem_cache_free(xfs_buf_item_zone, bip);
  			xfs_err(mp,
  	"buffer item dirty bitmap (%u uints) too small to reflect %u bytes!",
  					map_size,
  					BBTOB(bp->b_maps[i].bm_len));
  			return -EFSCORRUPTED;
  		}

  		bip->bli_formats[i].blf_type = XFS_LI_BUF;
  		bip->bli_formats[i].blf_blkno = bp->b_maps[i].bm_bn;
  		bip->bli_formats[i].blf_len = bp->b_maps[i].bm_len;
  		bip->bli_formats[i].blf_map_size = map_size;
  	}

  	bp->b_log_item = bip;

  	xfs_buf_hold(bp);
  	return 0;

  }
  
  
  /*
   * Mark bytes first through last inclusive as dirty in the buf
   * item's bitmap.
   */

  static void

  xfs_buf_item_log_segment(

  	uint			first,

  	uint			last,
  	uint			*map)

  {
  	uint		first_bit;
  	uint		last_bit;
  	uint		bits_to_set;
  	uint		bits_set;
  	uint		word_num;
  	uint		*wordp;
  	uint		bit;
  	uint		end_bit;
  	uint		mask;

  	ASSERT(first < XFS_BLF_DATAMAP_SIZE * XFS_BLF_CHUNK * NBWORD);
  	ASSERT(last < XFS_BLF_DATAMAP_SIZE * XFS_BLF_CHUNK * NBWORD);

  	/*

  	 * Convert byte offsets to bit numbers.
  	 */

  	first_bit = first >> XFS_BLF_SHIFT;
  	last_bit = last >> XFS_BLF_SHIFT;

  
  	/*
  	 * Calculate the total number of bits to be set.
  	 */
  	bits_to_set = last_bit - first_bit + 1;
  
  	/*
  	 * Get a pointer to the first word in the bitmap
  	 * to set a bit in.
  	 */
  	word_num = first_bit >> BIT_TO_WORD_SHIFT;

  	wordp = &map[word_num];

  
  	/*
  	 * Calculate the starting bit in the first word.
  	 */
  	bit = first_bit & (uint)(NBWORD - 1);
  
  	/*
  	 * First set any bits in the first word of our range.
  	 * If it starts at bit 0 of the word, it will be
  	 * set below rather than here.  That is what the variable
  	 * bit tells us. The variable bits_set tracks the number
  	 * of bits that have been set so far.  End_bit is the number
  	 * of the last bit to be set in this word plus one.
  	 */
  	if (bit) {

  		end_bit = min(bit + bits_to_set, (uint)NBWORD);

  		mask = ((1U << (end_bit - bit)) - 1) << bit;

  		*wordp |= mask;
  		wordp++;
  		bits_set = end_bit - bit;
  	} else {
  		bits_set = 0;
  	}
  
  	/*
  	 * Now set bits a whole word at a time that are between
  	 * first_bit and last_bit.
  	 */
  	while ((bits_to_set - bits_set) >= NBWORD) {

  		*wordp = 0xffffffff;

  		bits_set += NBWORD;
  		wordp++;
  	}
  
  	/*
  	 * Finally, set any bits left to be set in one last partial word.
  	 */
  	end_bit = bits_to_set - bits_set;
  	if (end_bit) {

  		mask = (1U << end_bit) - 1;

  		*wordp |= mask;
  	}

  }

  /*
   * Mark bytes first through last inclusive as dirty in the buf
   * item's bitmap.
   */
  void
  xfs_buf_item_log(

  	struct xfs_buf_log_item	*bip,

  	uint			first,
  	uint			last)
  {
  	int			i;
  	uint			start;
  	uint			end;
  	struct xfs_buf		*bp = bip->bli_buf;
  
  	/*

  	 * walk each buffer segment and mark them dirty appropriately.
  	 */
  	start = 0;
  	for (i = 0; i < bip->bli_format_count; i++) {
  		if (start > last)
  			break;

  		end = start + BBTOB(bp->b_maps[i].bm_len) - 1;
  
  		/* skip to the map that includes the first byte to log */

  		if (first > end) {
  			start += BBTOB(bp->b_maps[i].bm_len);
  			continue;
  		}

  
  		/*
  		 * Trim the range to this segment and mark it in the bitmap.
  		 * Note that we must convert buffer offsets to segment relative
  		 * offsets (e.g., the first byte of each segment is byte 0 of
  		 * that segment).
  		 */

  		if (first < start)
  			first = start;
  		if (end > last)
  			end = last;

  		xfs_buf_item_log_segment(first - start, end - start,

  					 &bip->bli_formats[i].blf_data_map[0]);

  		start += BBTOB(bp->b_maps[i].bm_len);

  	}
  }

  /*
   * Return true if the buffer has any ranges logged/dirtied by a transaction,
   * false otherwise.
   */
  bool
  xfs_buf_item_dirty_format(
  	struct xfs_buf_log_item	*bip)
  {
  	int			i;
  
  	for (i = 0; i < bip->bli_format_count; i++) {
  		if (!xfs_bitmap_empty(bip->bli_formats[i].blf_data_map,
  			     bip->bli_formats[i].blf_map_size))
  			return true;
  	}
  
  	return false;
  }

  STATIC void
  xfs_buf_item_free(

  	struct xfs_buf_log_item	*bip)

  {

  	xfs_buf_item_free_format(bip);

  	kmem_free(bip->bli_item.li_lv_shadow);

  	kmem_cache_free(xfs_buf_item_zone, bip);

  }

  /*

   * xfs_buf_item_relse() is called when the buf log item is no longer needed.

   */
  void
  xfs_buf_item_relse(
  	xfs_buf_t	*bp)
  {

  	struct xfs_buf_log_item	*bip = bp->b_log_item;

  	trace_xfs_buf_item_relse(bp, _RET_IP_);

  	ASSERT(!test_bit(XFS_LI_IN_AIL, &bip->bli_item.li_flags));

  	bp->b_log_item = NULL;

  	xfs_buf_rele(bp);
  	xfs_buf_item_free(bip);

  }

  void

  xfs_buf_item_done(

  	struct xfs_buf		*bp)
  {

  	/*
  	 * If we are forcibly shutting down, this may well be off the AIL
  	 * already. That's because we simulate the log-committed callbacks to
  	 * unpin these buffers. Or we may never have put this item on AIL
  	 * because of the transaction was aborted forcibly.
  	 * xfs_trans_ail_delete() takes care of these.
  	 *
  	 * Either way, AIL is useless if we're forcing a shutdown.

  	 *
  	 * Note that log recovery writes might have buffer items that are not on
  	 * the AIL even when the file system is not shut down.

  	 */

  	xfs_trans_ail_delete(&bp->b_log_item->bli_item,

  			     (bp->b_flags & _XBF_LOGRECOVERY) ? 0 :

  			     SHUTDOWN_CORRUPT_INCORE);
  	xfs_buf_item_relse(bp);

  }