patch-2.4.25 linux-2.4.25/fs/xfs/xfs_buf_item.c

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diff -urN linux-2.4.24/fs/xfs/xfs_buf_item.c linux-2.4.25/fs/xfs/xfs_buf_item.c
@@ -0,0 +1,1223 @@
+/*
+ * Copyright (c) 2000-2002 Silicon Graphics, Inc.  All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * Further, this software is distributed without any warranty that it is
+ * free of the rightful claim of any third person regarding infringement
+ * or the like.  Any license provided herein, whether implied or
+ * otherwise, applies only to this software file.  Patent licenses, if
+ * any, provided herein do not apply to combinations of this program with
+ * other software, or any other product whatsoever.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write the Free Software Foundation, Inc., 59
+ * Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
+ * Mountain View, CA  94043, or:
+ *
+ * http://www.sgi.com
+ *
+ * For further information regarding this notice, see:
+ *
+ * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
+ */
+
+/*
+ * This file contains the implementation of the xfs_buf_log_item.
+ * It contains the item operations used to manipulate the buf log
+ * items as well as utility routines used by the buffer specific
+ * transaction routines.
+ */
+
+#include "xfs.h"
+
+#include "xfs_macros.h"
+#include "xfs_types.h"
+#include "xfs_inum.h"
+#include "xfs_log.h"
+#include "xfs_trans.h"
+#include "xfs_buf_item.h"
+#include "xfs_sb.h"
+#include "xfs_dir.h"
+#include "xfs_dmapi.h"
+#include "xfs_mount.h"
+#include "xfs_trans_priv.h"
+#include "xfs_rw.h"
+#include "xfs_bit.h"
+#include "xfs_error.h"
+
+
+#define	ROUNDUPNBWORD(x)	(((x) + (NBWORD - 1)) & ~(NBWORD - 1))
+
+kmem_zone_t	*xfs_buf_item_zone;
+
+#ifdef XFS_TRANS_DEBUG
+/*
+ * This function uses an alternate strategy for tracking the bytes
+ * that the user requests to be logged.  This can then be used
+ * in conjunction with the bli_orig array in the buf log item to
+ * catch bugs in our callers' code.
+ *
+ * We also double check the bits set in xfs_buf_item_log using a
+ * simple algorithm to check that every byte is accounted for.
+ */
+STATIC void
+xfs_buf_item_log_debug(
+	xfs_buf_log_item_t	*bip,
+	uint			first,
+	uint			last)
+{
+	uint	x;
+	uint	byte;
+	uint	nbytes;
+	uint	chunk_num;
+	uint	word_num;
+	uint	bit_num;
+	uint	bit_set;
+	uint	*wordp;
+
+	ASSERT(bip->bli_logged != NULL);
+	byte = first;
+	nbytes = last - first + 1;
+	bfset(bip->bli_logged, first, nbytes);
+	for (x = 0; x < nbytes; x++) {
+		chunk_num = byte >> XFS_BLI_SHIFT;
+		word_num = chunk_num >> BIT_TO_WORD_SHIFT;
+		bit_num = chunk_num & (NBWORD - 1);
+		wordp = &(bip->bli_format.blf_data_map[word_num]);
+		bit_set = *wordp & (1 << bit_num);
+		ASSERT(bit_set);
+		byte++;
+	}
+}
+
+/*
+ * This function is called when we flush something into a buffer without
+ * logging it.  This happens for things like inodes which are logged
+ * separately from the buffer.
+ */
+void
+xfs_buf_item_flush_log_debug(
+	xfs_buf_t	*bp,
+	uint		first,
+	uint		last)
+{
+	xfs_buf_log_item_t	*bip;
+	uint			nbytes;
+
+	bip = XFS_BUF_FSPRIVATE(bp, xfs_buf_log_item_t*);
+	if ((bip == NULL) || (bip->bli_item.li_type != XFS_LI_BUF)) {
+		return;
+	}
+
+	ASSERT(bip->bli_logged != NULL);
+	nbytes = last - first + 1;
+	bfset(bip->bli_logged, first, nbytes);
+}
+
+/*
+ * This function is called to verify that our caller's have logged
+ * all the bytes that they changed.
+ *
+ * It does this by comparing the original copy of the buffer stored in
+ * the buf log item's bli_orig array to the current copy of the buffer
+ * and ensuring that all bytes which miscompare are set in the bli_logged
+ * array of the buf log item.
+ */
+STATIC void
+xfs_buf_item_log_check(
+	xfs_buf_log_item_t	*bip)
+{
+	char		*orig;
+	char		*buffer;
+	int		x;
+	xfs_buf_t	*bp;
+
+	ASSERT(bip->bli_orig != NULL);
+	ASSERT(bip->bli_logged != NULL);
+
+	bp = bip->bli_buf;
+	ASSERT(XFS_BUF_COUNT(bp) > 0);
+	ASSERT(XFS_BUF_PTR(bp) != NULL);
+	orig = bip->bli_orig;
+	buffer = XFS_BUF_PTR(bp);
+	for (x = 0; x < XFS_BUF_COUNT(bp); x++) {
+		if (orig[x] != buffer[x] && !btst(bip->bli_logged, x))
+			cmn_err(CE_PANIC,
+	"xfs_buf_item_log_check bip %x buffer %x orig %x index %d",
+				bip, bp, orig, x);
+	}
+}
+#else
+#define		xfs_buf_item_log_debug(x,y,z)
+#define		xfs_buf_item_log_check(x)
+#endif
+
+STATIC void	xfs_buf_error_relse(xfs_buf_t *bp);
+STATIC void	xfs_buf_do_callbacks(xfs_buf_t *bp, xfs_log_item_t *lip);
+
+/*
+ * 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.
+ */
+uint
+xfs_buf_item_size(
+	xfs_buf_log_item_t	*bip)
+{
+	uint		nvecs;
+	int		next_bit;
+	int		last_bit;
+	xfs_buf_t	*bp;
+
+	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.
+		 */
+		xfs_buf_item_trace("SIZE STALE", bip);
+		ASSERT(bip->bli_format.blf_flags & XFS_BLI_CANCEL);
+		return 1;
+	}
+
+	bp = bip->bli_buf;
+	ASSERT(bip->bli_flags & XFS_BLI_LOGGED);
+	nvecs = 1;
+	last_bit = xfs_next_bit(bip->bli_format.blf_data_map,
+					 bip->bli_format.blf_map_size, 0);
+	ASSERT(last_bit != -1);
+	nvecs++;
+	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(bip->bli_format.blf_data_map,
+						 bip->bli_format.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) {
+			last_bit = -1;
+		} else if (next_bit != last_bit + 1) {
+			last_bit = next_bit;
+			nvecs++;
+		} else if (xfs_buf_offset(bp, next_bit * XFS_BLI_CHUNK) !=
+			   (xfs_buf_offset(bp, last_bit * XFS_BLI_CHUNK) +
+			    XFS_BLI_CHUNK)) {
+			last_bit = next_bit;
+			nvecs++;
+		} else {
+			last_bit++;
+		}
+	}
+
+	xfs_buf_item_trace("SIZE NORM", bip);
+	return nvecs;
+}
+
+/*
+ * 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.
+ */
+void
+xfs_buf_item_format(
+	xfs_buf_log_item_t	*bip,
+	xfs_log_iovec_t		*log_vector)
+{
+	uint		base_size;
+	uint		nvecs;
+	xfs_log_iovec_t	*vecp;
+	xfs_buf_t	*bp;
+	int		first_bit;
+	int		last_bit;
+	int		next_bit;
+	uint		nbits;
+	uint		buffer_offset;
+
+	ASSERT(atomic_read(&bip->bli_refcount) > 0);
+	ASSERT((bip->bli_flags & XFS_BLI_LOGGED) ||
+	       (bip->bli_flags & XFS_BLI_STALE));
+	bp = bip->bli_buf;
+	ASSERT(XFS_BUF_BP_ISMAPPED(bp));
+	vecp = log_vector;
+
+	/*
+	 * The size of the base structure is the size of the
+	 * declared structure plus the space for the extra words
+	 * of the bitmap.  We subtract one from the map size, because
+	 * the first element of the bitmap is accounted for in the
+	 * size of the base structure.
+	 */
+	base_size =
+		(uint)(sizeof(xfs_buf_log_format_t) +
+		       ((bip->bli_format.blf_map_size - 1) * sizeof(uint)));
+	vecp->i_addr = (xfs_caddr_t)&bip->bli_format;
+	vecp->i_len = base_size;
+	vecp++;
+	nvecs = 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.
+		 */
+		xfs_buf_item_trace("FORMAT STALE", bip);
+		ASSERT(bip->bli_format.blf_flags & XFS_BLI_CANCEL);
+		bip->bli_format.blf_size = nvecs;
+		return;
+	}
+
+	/*
+	 * Fill in an iovec for each set of contiguous chunks.
+	 */
+	first_bit = xfs_next_bit(bip->bli_format.blf_data_map,
+					 bip->bli_format.blf_map_size, 0);
+	ASSERT(first_bit != -1);
+	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(bip->bli_format.blf_data_map,
+						 bip->bli_format.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) {
+			buffer_offset = first_bit * XFS_BLI_CHUNK;
+			vecp->i_addr = xfs_buf_offset(bp, buffer_offset);
+			vecp->i_len = nbits * XFS_BLI_CHUNK;
+			nvecs++;
+			break;
+		} else if (next_bit != last_bit + 1) {
+			buffer_offset = first_bit * XFS_BLI_CHUNK;
+			vecp->i_addr = xfs_buf_offset(bp, buffer_offset);
+			vecp->i_len = nbits * XFS_BLI_CHUNK;
+			nvecs++;
+			vecp++;
+			first_bit = next_bit;
+			last_bit = next_bit;
+			nbits = 1;
+		} else if (xfs_buf_offset(bp, next_bit << XFS_BLI_SHIFT) !=
+			   (xfs_buf_offset(bp, last_bit << XFS_BLI_SHIFT) +
+			    XFS_BLI_CHUNK)) {
+			buffer_offset = first_bit * XFS_BLI_CHUNK;
+			vecp->i_addr = xfs_buf_offset(bp, buffer_offset);
+			vecp->i_len = nbits * XFS_BLI_CHUNK;
+/* You would think we need to bump the nvecs here too, but we do not
+ * this number is used by recovery, and it gets confused by the boundary
+ * split here
+ *			nvecs++;
+ */
+			vecp++;
+			first_bit = next_bit;
+			last_bit = next_bit;
+			nbits = 1;
+		} else {
+			last_bit++;
+			nbits++;
+		}
+	}
+	bip->bli_format.blf_size = nvecs;
+
+	/*
+	 * Check to make sure everything is consistent.
+	 */
+	xfs_buf_item_trace("FORMAT NORM", bip);
+	xfs_buf_item_log_check(bip);
+}
+
+/*
+ * This is called to pin the buffer associated with the buf log
+ * item in memory so it cannot be written out.  Simply call bpin()
+ * on the buffer to do this.
+ */
+void
+xfs_buf_item_pin(
+	xfs_buf_log_item_t	*bip)
+{
+	xfs_buf_t	*bp;
+
+	bp = bip->bli_buf;
+	ASSERT(XFS_BUF_ISBUSY(bp));
+	ASSERT(atomic_read(&bip->bli_refcount) > 0);
+	ASSERT((bip->bli_flags & XFS_BLI_LOGGED) ||
+	       (bip->bli_flags & XFS_BLI_STALE));
+	xfs_buf_item_trace("PIN", bip);
+	xfs_buftrace("XFS_PIN", bp);
+	xfs_bpin(bp);
+}
+
+
+/*
+ * 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().
+ * Just call bunpin() on the buffer to do this.
+ *
+ * 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.
+ */
+void
+xfs_buf_item_unpin(
+	xfs_buf_log_item_t	*bip,
+	int			stale)
+{
+	xfs_mount_t	*mp;
+	xfs_buf_t	*bp;
+	int		freed;
+	SPLDECL(s);
+
+	bp = bip->bli_buf;
+	ASSERT(bp != NULL);
+	ASSERT(XFS_BUF_FSPRIVATE(bp, xfs_buf_log_item_t *) == bip);
+	ASSERT(atomic_read(&bip->bli_refcount) > 0);
+	xfs_buf_item_trace("UNPIN", bip);
+	xfs_buftrace("XFS_UNPIN", bp);
+
+	freed = atomic_dec_and_test(&bip->bli_refcount);
+	mp = bip->bli_item.li_mountp;
+	xfs_bunpin(bp);
+	if (freed && stale) {
+		ASSERT(bip->bli_flags & XFS_BLI_STALE);
+		ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
+		ASSERT(!(XFS_BUF_ISDELAYWRITE(bp)));
+		ASSERT(XFS_BUF_ISSTALE(bp));
+		ASSERT(bip->bli_format.blf_flags & XFS_BLI_CANCEL);
+		xfs_buf_item_trace("UNPIN STALE", bip);
+		xfs_buftrace("XFS_UNPIN STALE", bp);
+		/*
+		 * If we get called here because of an IO error, we may
+		 * or may not have the item on the AIL. xfs_trans_delete_ail()
+		 * will take care of that situation.
+		 * xfs_trans_delete_ail() drops the AIL lock.
+		 */
+		if (bip->bli_flags & XFS_BLI_STALE_INODE) {
+			xfs_buf_do_callbacks(bp, (xfs_log_item_t *)bip);
+			XFS_BUF_FSPRIVATE(bp, void *) = NULL;
+			XFS_BUF_CLR_IODONE_FUNC(bp);
+		} else {
+			AIL_LOCK(mp,s);
+			xfs_trans_delete_ail(mp, (xfs_log_item_t *)bip, s);
+			xfs_buf_item_relse(bp);
+			ASSERT(XFS_BUF_FSPRIVATE(bp, void *) == NULL);
+		}
+		xfs_buf_relse(bp);
+	}
+}
+
+/*
+ * this is called from uncommit in the forced-shutdown path.
+ * we need to check to see if the reference count on the log item
+ * is going to drop to zero.  If so, unpin will free the log item
+ * so we need to free the item's descriptor (that points to the item)
+ * in the transaction.
+ */
+void
+xfs_buf_item_unpin_remove(
+	xfs_buf_log_item_t	*bip,
+	xfs_trans_t		*tp)
+{
+	xfs_buf_t		*bp;
+	xfs_log_item_desc_t	*lidp;
+	int			stale = 0;
+
+	bp = bip->bli_buf;
+	/*
+	 * will xfs_buf_item_unpin() call xfs_buf_item_relse()?
+	 */
+	if ((atomic_read(&bip->bli_refcount) == 1) &&
+	    (bip->bli_flags & XFS_BLI_STALE)) {
+		ASSERT(XFS_BUF_VALUSEMA(bip->bli_buf) <= 0);
+		xfs_buf_item_trace("UNPIN REMOVE", bip);
+		xfs_buftrace("XFS_UNPIN_REMOVE", bp);
+		/*
+		 * yes -- clear the xaction descriptor in-use flag
+		 * and free the chunk if required.  We can safely
+		 * do some work here and then call buf_item_unpin
+		 * to do the rest because if the if is true, then
+		 * we are holding the buffer locked so no one else
+		 * will be able to bump up the refcount.
+		 */
+		lidp = xfs_trans_find_item(tp, (xfs_log_item_t *) bip);
+		stale = lidp->lid_flags & XFS_LID_BUF_STALE;
+		xfs_trans_free_item(tp, lidp);
+		/*
+		 * Since the transaction no longer refers to the buffer,
+		 * the buffer should no longer refer to the transaction.
+		 */
+		XFS_BUF_SET_FSPRIVATE2(bp, NULL);
+	}
+
+	xfs_buf_item_unpin(bip, stale);
+
+	return;
+}
+
+/*
+ * This is called to attempt to lock the buffer associated with this
+ * buf log item.  Don't sleep on the buffer lock.  If we can't get
+ * the lock right away, return 0.  If we can get the lock, pull the
+ * buffer from the free list, mark it busy, and return 1.
+ */
+uint
+xfs_buf_item_trylock(
+	xfs_buf_log_item_t	*bip)
+{
+	xfs_buf_t	*bp;
+
+	bp = bip->bli_buf;
+
+	if (XFS_BUF_ISPINNED(bp)) {
+		return XFS_ITEM_PINNED;
+	}
+
+	if (!XFS_BUF_CPSEMA(bp)) {
+		return XFS_ITEM_LOCKED;
+	}
+
+	/*
+	 * Remove the buffer from the free list.  Only do this
+	 * if it's on the free list.  Private buffers like the
+	 * superblock buffer are not.
+	 */
+	XFS_BUF_HOLD(bp);
+
+	ASSERT(!(bip->bli_flags & XFS_BLI_STALE));
+	xfs_buf_item_trace("TRYLOCK SUCCESS", bip);
+	return XFS_ITEM_SUCCESS;
+}
+
+/*
+ * 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.
+ *
+ * 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.
+ */
+void
+xfs_buf_item_unlock(
+	xfs_buf_log_item_t	*bip)
+{
+	int		aborted;
+	xfs_buf_t	*bp;
+	uint		hold;
+
+	bp = bip->bli_buf;
+	xfs_buftrace("XFS_UNLOCK", bp);
+
+	/*
+	 * Clear the buffer's association with this transaction.
+	 */
+	XFS_BUF_SET_FSPRIVATE2(bp, NULL);
+
+	/*
+	 * If this is a transaction abort, don't return early.
+	 * Instead, allow the brelse to happen.
+	 * Normally it would be done for stale (cancelled) buffers
+	 * at unpin time, but we'll never go through the pin/unpin
+	 * cycle if we abort inside commit.
+	 */
+	aborted = (bip->bli_item.li_flags & XFS_LI_ABORTED) != 0;
+
+	/*
+	 * If the buf item is marked stale, then don't do anything.
+	 * We'll unlock the buffer and free the buf item when the
+	 * buffer is unpinned for the last time.
+	 */
+	if (bip->bli_flags & XFS_BLI_STALE) {
+		bip->bli_flags &= ~XFS_BLI_LOGGED;
+		xfs_buf_item_trace("UNLOCK STALE", bip);
+		ASSERT(bip->bli_format.blf_flags & XFS_BLI_CANCEL);
+		if (!aborted)
+			return;
+	}
+
+	/*
+	 * Drop the transaction's reference to the log item if
+	 * it was not logged as part of the transaction.  Otherwise
+	 * we'll drop the reference in xfs_buf_item_unpin() when
+	 * the transaction is really through with the buffer.
+	 */
+	if (!(bip->bli_flags & XFS_BLI_LOGGED)) {
+		atomic_dec(&bip->bli_refcount);
+	} else {
+		/*
+		 * Clear the logged flag since this is per
+		 * transaction state.
+		 */
+		bip->bli_flags &= ~XFS_BLI_LOGGED;
+	}
+
+	/*
+	 * Before possibly freeing the buf item, determine if we should
+	 * release the buffer at the end of this routine.
+	 */
+	hold = bip->bli_flags & XFS_BLI_HOLD;
+	xfs_buf_item_trace("UNLOCK", bip);
+
+	/*
+	 * If the buf item isn't tracking any data, free it.
+	 * Otherwise, if XFS_BLI_HOLD is set clear it.
+	 */
+	if (xfs_count_bits(bip->bli_format.blf_data_map,
+			      bip->bli_format.blf_map_size, 0) == 0) {
+		xfs_buf_item_relse(bp);
+	} else if (hold) {
+		bip->bli_flags &= ~XFS_BLI_HOLD;
+	}
+
+	/*
+	 * Release the buffer if XFS_BLI_HOLD was not set.
+	 */
+	if (!hold) {
+		xfs_buf_relse(bp);
+	}
+}
+
+/*
+ * 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.
+ */
+xfs_lsn_t
+xfs_buf_item_committed(
+	xfs_buf_log_item_t	*bip,
+	xfs_lsn_t		lsn)
+{
+	xfs_buf_item_trace("COMMITTED", bip);
+	if ((bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF) &&
+	    (bip->bli_item.li_lsn != 0)) {
+		return bip->bli_item.li_lsn;
+	}
+	return (lsn);
+}
+
+/*
+ * This is called when the transaction holding the buffer is aborted.
+ * Just behave as if the transaction had been cancelled. If we're shutting down
+ * and have aborted this transaction, we'll trap this buffer when it tries to
+ * get written out.
+ */
+void
+xfs_buf_item_abort(
+	xfs_buf_log_item_t	*bip)
+{
+	xfs_buf_t	*bp;
+
+	bp = bip->bli_buf;
+	xfs_buftrace("XFS_ABORT", bp);
+	XFS_BUF_SUPER_STALE(bp);
+	xfs_buf_item_unlock(bip);
+	return;
+}
+
+/*
+ * This is called to asynchronously write the buffer associated with this
+ * buf log item out to disk. The buffer will already have been locked by
+ * a successful call to xfs_buf_item_trylock().  If the buffer still has
+ * B_DELWRI set, then get it going out to disk with a call to bawrite().
+ * If not, then just release the buffer.
+ */
+void
+xfs_buf_item_push(
+	xfs_buf_log_item_t	*bip)
+{
+	xfs_buf_t	*bp;
+
+	ASSERT(!(bip->bli_flags & XFS_BLI_STALE));
+	xfs_buf_item_trace("PUSH", bip);
+
+	bp = bip->bli_buf;
+
+	if (XFS_BUF_ISDELAYWRITE(bp)) {
+		xfs_bawrite(bip->bli_item.li_mountp, bp);
+	} else {
+		xfs_buf_relse(bp);
+	}
+}
+
+/* ARGSUSED */
+void
+xfs_buf_item_committing(xfs_buf_log_item_t *bip, xfs_lsn_t commit_lsn)
+{
+}
+
+/*
+ * This is the ops vector shared by all buf log items.
+ */
+struct xfs_item_ops xfs_buf_item_ops = {
+	.iop_size	= (uint(*)(xfs_log_item_t*))xfs_buf_item_size,
+	.iop_format	= (void(*)(xfs_log_item_t*, xfs_log_iovec_t*))
+					xfs_buf_item_format,
+	.iop_pin	= (void(*)(xfs_log_item_t*))xfs_buf_item_pin,
+	.iop_unpin	= (void(*)(xfs_log_item_t*, int))xfs_buf_item_unpin,
+	.iop_unpin_remove = (void(*)(xfs_log_item_t*, xfs_trans_t *))
+					xfs_buf_item_unpin_remove,
+	.iop_trylock	= (uint(*)(xfs_log_item_t*))xfs_buf_item_trylock,
+	.iop_unlock	= (void(*)(xfs_log_item_t*))xfs_buf_item_unlock,
+	.iop_committed	= (xfs_lsn_t(*)(xfs_log_item_t*, xfs_lsn_t))
+					xfs_buf_item_committed,
+	.iop_push	= (void(*)(xfs_log_item_t*))xfs_buf_item_push,
+	.iop_abort	= (void(*)(xfs_log_item_t*))xfs_buf_item_abort,
+	.iop_pushbuf	= NULL,
+	.iop_committing = (void(*)(xfs_log_item_t*, xfs_lsn_t))
+					xfs_buf_item_committing
+};
+
+
+/*
+ * Allocate a new buf log item to go with the given buffer.
+ * Set the buffer's b_fsprivate field to point to the new
+ * buf log item.  If there are other item's attached to the
+ * buffer (see xfs_buf_attach_iodone() below), then put the
+ * buf log item at the front.
+ */
+void
+xfs_buf_item_init(
+	xfs_buf_t	*bp,
+	xfs_mount_t	*mp)
+{
+	xfs_log_item_t		*lip;
+	xfs_buf_log_item_t	*bip;
+	int			chunks;
+	int			map_size;
+
+	/*
+	 * Check to see if there is already a buf log item for
+	 * this buffer.  If there is, it is guaranteed to be
+	 * the first.  If we do already have one, there is
+	 * nothing to do here so return.
+	 */
+	if (XFS_BUF_FSPRIVATE3(bp, xfs_mount_t *) != mp)
+		XFS_BUF_SET_FSPRIVATE3(bp, mp);
+	XFS_BUF_SET_BDSTRAT_FUNC(bp, xfs_bdstrat_cb);
+	if (XFS_BUF_FSPRIVATE(bp, void *) != NULL) {
+		lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
+		if (lip->li_type == XFS_LI_BUF) {
+			return;
+		}
+	}
+
+	/*
+	 * chunks is the number of XFS_BLI_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.
+	 */
+	chunks = (int)((XFS_BUF_COUNT(bp) + (XFS_BLI_CHUNK - 1)) >> XFS_BLI_SHIFT);
+	map_size = (int)((chunks + NBWORD) >> BIT_TO_WORD_SHIFT);
+
+	bip = (xfs_buf_log_item_t*)kmem_zone_zalloc(xfs_buf_item_zone,
+						    KM_SLEEP);
+	bip->bli_item.li_type = XFS_LI_BUF;
+	bip->bli_item.li_ops = &xfs_buf_item_ops;
+	bip->bli_item.li_mountp = mp;
+	bip->bli_buf = bp;
+	bip->bli_format.blf_type = XFS_LI_BUF;
+	bip->bli_format.blf_blkno = (__int64_t)XFS_BUF_ADDR(bp);
+	bip->bli_format.blf_len = (ushort)BTOBB(XFS_BUF_COUNT(bp));
+	bip->bli_format.blf_map_size = map_size;
+#ifdef XFS_BLI_TRACE
+	bip->bli_trace = ktrace_alloc(XFS_BLI_TRACE_SIZE, KM_SLEEP);
+#endif
+
+#ifdef XFS_TRANS_DEBUG
+	/*
+	 * Allocate the arrays for tracking what needs to be logged
+	 * and what our callers request to be logged.  bli_orig
+	 * holds a copy of the original, clean buffer for comparison
+	 * against, and bli_logged keeps a 1 bit flag per byte in
+	 * the buffer to indicate which bytes the callers have asked
+	 * to have logged.
+	 */
+	bip->bli_orig = (char *)kmem_alloc(XFS_BUF_COUNT(bp), KM_SLEEP);
+	memcpy(bip->bli_orig, XFS_BUF_PTR(bp), XFS_BUF_COUNT(bp));
+	bip->bli_logged = (char *)kmem_zalloc(XFS_BUF_COUNT(bp) / NBBY, KM_SLEEP);
+#endif
+
+	/*
+	 * Put the buf item into the list of items attached to the
+	 * buffer at the front.
+	 */
+	if (XFS_BUF_FSPRIVATE(bp, void *) != NULL) {
+		bip->bli_item.li_bio_list =
+				XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
+	}
+	XFS_BUF_SET_FSPRIVATE(bp, bip);
+}
+
+
+/*
+ * Mark bytes first through last inclusive as dirty in the buf
+ * item's bitmap.
+ */
+void
+xfs_buf_item_log(
+	xfs_buf_log_item_t	*bip,
+	uint			first,
+	uint			last)
+{
+	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;
+
+	/*
+	 * Mark the item as having some dirty data for
+	 * quick reference in xfs_buf_item_dirty.
+	 */
+	bip->bli_flags |= XFS_BLI_DIRTY;
+
+	/*
+	 * Convert byte offsets to bit numbers.
+	 */
+	first_bit = first >> XFS_BLI_SHIFT;
+	last_bit = last >> XFS_BLI_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 = &(bip->bli_format.blf_data_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 = ((1 << (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 = (1 << end_bit) - 1;
+		*wordp |= mask;
+	}
+
+	xfs_buf_item_log_debug(bip, first, last);
+}
+
+
+/*
+ * Return 1 if the buffer has some data that has been logged (at any
+ * point, not just the current transaction) and 0 if not.
+ */
+uint
+xfs_buf_item_dirty(
+	xfs_buf_log_item_t	*bip)
+{
+	return (bip->bli_flags & XFS_BLI_DIRTY);
+}
+
+/*
+ * This is called when the buf log item is no longer needed.  It should
+ * free the buf log item associated with the given buffer and clear
+ * the buffer's pointer to the buf log item.  If there are no more
+ * items in the list, clear the b_iodone field of the buffer (see
+ * xfs_buf_attach_iodone() below).
+ */
+void
+xfs_buf_item_relse(
+	xfs_buf_t	*bp)
+{
+	xfs_buf_log_item_t	*bip;
+
+	xfs_buftrace("XFS_RELSE", bp);
+	bip = XFS_BUF_FSPRIVATE(bp, xfs_buf_log_item_t*);
+	XFS_BUF_SET_FSPRIVATE(bp, bip->bli_item.li_bio_list);
+	if ((XFS_BUF_FSPRIVATE(bp, void *) == NULL) &&
+	    (XFS_BUF_IODONE_FUNC(bp) != NULL)) {
+		ASSERT((XFS_BUF_ISUNINITIAL(bp)) == 0);
+		XFS_BUF_CLR_IODONE_FUNC(bp);
+	}
+
+#ifdef XFS_TRANS_DEBUG
+	kmem_free(bip->bli_orig, XFS_BUF_COUNT(bp));
+	bip->bli_orig = NULL;
+	kmem_free(bip->bli_logged, XFS_BUF_COUNT(bp) / NBBY);
+	bip->bli_logged = NULL;
+#endif /* XFS_TRANS_DEBUG */
+
+#ifdef XFS_BLI_TRACE
+	ktrace_free(bip->bli_trace);
+#endif
+	kmem_zone_free(xfs_buf_item_zone, bip);
+}
+
+
+/*
+ * Add the given log item with its callback to the list of callbacks
+ * to be called when the buffer's I/O completes.  If it is not set
+ * already, set the buffer's b_iodone() routine to be
+ * xfs_buf_iodone_callbacks() and link the log item into the list of
+ * items rooted at b_fsprivate.  Items are always added as the second
+ * entry in the list if there is a first, because the buf item code
+ * assumes that the buf log item is first.
+ */
+void
+xfs_buf_attach_iodone(
+	xfs_buf_t	*bp,
+	void		(*cb)(xfs_buf_t *, xfs_log_item_t *),
+	xfs_log_item_t	*lip)
+{
+	xfs_log_item_t	*head_lip;
+
+	ASSERT(XFS_BUF_ISBUSY(bp));
+	ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
+
+	lip->li_cb = cb;
+	if (XFS_BUF_FSPRIVATE(bp, void *) != NULL) {
+		head_lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
+		lip->li_bio_list = head_lip->li_bio_list;
+		head_lip->li_bio_list = lip;
+	} else {
+		XFS_BUF_SET_FSPRIVATE(bp, lip);
+	}
+
+	ASSERT((XFS_BUF_IODONE_FUNC(bp) == xfs_buf_iodone_callbacks) ||
+	       (XFS_BUF_IODONE_FUNC(bp) == NULL));
+	XFS_BUF_SET_IODONE_FUNC(bp, xfs_buf_iodone_callbacks);
+}
+
+STATIC void
+xfs_buf_do_callbacks(
+	xfs_buf_t	*bp,
+	xfs_log_item_t	*lip)
+{
+	xfs_log_item_t	*nlip;
+
+	while (lip != NULL) {
+		nlip = lip->li_bio_list;
+		ASSERT(lip->li_cb != NULL);
+		/*
+		 * Clear the next pointer so we don't have any
+		 * confusion if the item is added to another buf.
+		 * Don't touch the log item after calling its
+		 * callback, because it could have freed itself.
+		 */
+		lip->li_bio_list = NULL;
+		lip->li_cb(bp, lip);
+		lip = nlip;
+	}
+}
+
+/*
+ * This is the iodone() function for buffers which have had callbacks
+ * attached to them by xfs_buf_attach_iodone().  It should remove each
+ * log item from the buffer's list and call the callback of each in turn.
+ * When done, the buffer's fsprivate field is set to NULL and the buffer
+ * is unlocked with a call to iodone().
+ */
+void
+xfs_buf_iodone_callbacks(
+	xfs_buf_t	*bp)
+{
+	xfs_log_item_t	*lip;
+	static ulong	lasttime;
+	static xfs_buftarg_t *lasttarg;
+	xfs_mount_t	*mp;
+
+	ASSERT(XFS_BUF_FSPRIVATE(bp, void *) != NULL);
+	lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
+
+	if (XFS_BUF_GETERROR(bp) != 0) {
+		/*
+		 * If we've already decided to shutdown the filesystem
+		 * because of IO errors, there's no point in giving this
+		 * a retry.
+		 */
+		mp = lip->li_mountp;
+		if (XFS_FORCED_SHUTDOWN(mp)) {
+			ASSERT(XFS_BUF_TARGET(bp) == mp->m_ddev_targp);
+			XFS_BUF_SUPER_STALE(bp);
+			xfs_buftrace("BUF_IODONE_CB", bp);
+			xfs_buf_do_callbacks(bp, lip);
+			XFS_BUF_SET_FSPRIVATE(bp, NULL);
+			XFS_BUF_CLR_IODONE_FUNC(bp);
+
+			/*
+			 * XFS_SHUT flag gets set when we go thru the
+			 * entire buffer cache and deliberately start
+			 * throwing away delayed write buffers.
+			 * Since there's no biowait done on those,
+			 * we should just brelse them.
+			 */
+			if (XFS_BUF_ISSHUT(bp)) {
+			    XFS_BUF_UNSHUT(bp);
+				xfs_buf_relse(bp);
+			} else {
+				xfs_biodone(bp);
+			}
+
+			return;
+		}
+
+		if ((XFS_BUF_TARGET(bp) != lasttarg) ||
+		    (time_after(jiffies, (lasttime + 5*HZ)))) {
+			lasttime = jiffies;
+			prdev("XFS write error in file system meta-data "
+			      "block 0x%Lx in %s",
+			      XFS_BUF_TARGET(bp),
+			      XFS_BUF_ADDR(bp), mp->m_fsname);
+		}
+		lasttarg = XFS_BUF_TARGET(bp);
+
+		if (XFS_BUF_ISASYNC(bp)) {
+			/*
+			 * If the write was asynchronous then noone will be
+			 * looking for the error.  Clear the error state
+			 * and write the buffer out again delayed write.
+			 *
+			 * XXXsup This is OK, so long as we catch these
+			 * before we start the umount; we don't want these
+			 * DELWRI metadata bufs to be hanging around.
+			 */
+			XFS_BUF_ERROR(bp,0); /* errno of 0 unsets the flag */
+
+			if (!(XFS_BUF_ISSTALE(bp))) {
+				XFS_BUF_DELAYWRITE(bp);
+				XFS_BUF_DONE(bp);
+				XFS_BUF_SET_START(bp);
+			}
+			ASSERT(XFS_BUF_IODONE_FUNC(bp));
+			xfs_buftrace("BUF_IODONE ASYNC", bp);
+			xfs_buf_relse(bp);
+		} else {
+			/*
+			 * If the write of the buffer was not asynchronous,
+			 * then we want to make sure to return the error
+			 * to the caller of bwrite().  Because of this we
+			 * cannot clear the B_ERROR state at this point.
+			 * Instead we install a callback function that
+			 * will be called when the buffer is released, and
+			 * that routine will clear the error state and
+			 * set the buffer to be written out again after
+			 * some delay.
+			 */
+			/* We actually overwrite the existing b-relse
+			   function at times, but we're gonna be shutting down
+			   anyway. */
+			XFS_BUF_SET_BRELSE_FUNC(bp,xfs_buf_error_relse);
+			XFS_BUF_DONE(bp);
+			XFS_BUF_V_IODONESEMA(bp);
+		}
+		return;
+	}
+#ifdef XFSERRORDEBUG
+	xfs_buftrace("XFS BUFCB NOERR", bp);
+#endif
+	xfs_buf_do_callbacks(bp, lip);
+	XFS_BUF_SET_FSPRIVATE(bp, NULL);
+	XFS_BUF_CLR_IODONE_FUNC(bp);
+	xfs_biodone(bp);
+}
+
+/*
+ * This is a callback routine attached to a buffer which gets an error
+ * when being written out synchronously.
+ */
+STATIC void
+xfs_buf_error_relse(
+	xfs_buf_t	*bp)
+{
+	xfs_log_item_t	*lip;
+	xfs_mount_t	*mp;
+
+	lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
+	mp = (xfs_mount_t *)lip->li_mountp;
+	ASSERT(XFS_BUF_TARGET(bp) == mp->m_ddev_targp);
+
+	XFS_BUF_STALE(bp);
+	XFS_BUF_DONE(bp);
+	XFS_BUF_UNDELAYWRITE(bp);
+	XFS_BUF_ERROR(bp,0);
+	xfs_buftrace("BUF_ERROR_RELSE", bp);
+	if (! XFS_FORCED_SHUTDOWN(mp))
+		xfs_force_shutdown(mp, XFS_METADATA_IO_ERROR);
+	/*
+	 * We have to unpin the pinned buffers so do the
+	 * callbacks.
+	 */
+	xfs_buf_do_callbacks(bp, lip);
+	XFS_BUF_SET_FSPRIVATE(bp, NULL);
+	XFS_BUF_CLR_IODONE_FUNC(bp);
+	XFS_BUF_SET_BRELSE_FUNC(bp,NULL);
+	xfs_buf_relse(bp);
+}
+
+
+/*
+ * This is the iodone() function for buffers which have been
+ * logged.  It is called when they are eventually flushed out.
+ * It should remove the buf item from the AIL, and free the buf item.
+ * It is called by xfs_buf_iodone_callbacks() above which will take
+ * care of cleaning up the buffer itself.
+ */
+/* ARGSUSED */
+void
+xfs_buf_iodone(
+	xfs_buf_t		*bp,
+	xfs_buf_log_item_t	*bip)
+{
+	struct xfs_mount	*mp;
+	SPLDECL(s);
+
+	ASSERT(bip->bli_buf == bp);
+
+	mp = bip->bli_item.li_mountp;
+
+	/*
+	 * 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_delete_ail() takes care of these.
+	 *
+	 * Either way, AIL is useless if we're forcing a shutdown.
+	 */
+	AIL_LOCK(mp,s);
+	/*
+	 * xfs_trans_delete_ail() drops the AIL lock.
+	 */
+	xfs_trans_delete_ail(mp, (xfs_log_item_t *)bip, s);
+
+#ifdef XFS_TRANS_DEBUG
+	kmem_free(bip->bli_orig, XFS_BUF_COUNT(bp));
+	bip->bli_orig = NULL;
+	kmem_free(bip->bli_logged, XFS_BUF_COUNT(bp) / NBBY);
+	bip->bli_logged = NULL;
+#endif /* XFS_TRANS_DEBUG */
+
+#ifdef XFS_BLI_TRACE
+	ktrace_free(bip->bli_trace);
+#endif
+	kmem_zone_free(xfs_buf_item_zone, bip);
+}
+
+#if defined(XFS_BLI_TRACE)
+void
+xfs_buf_item_trace(
+	char			*id,
+	xfs_buf_log_item_t	*bip)
+{
+	xfs_buf_t		*bp;
+	ASSERT(bip->bli_trace != NULL);
+
+	bp = bip->bli_buf;
+	ktrace_enter(bip->bli_trace,
+		     (void *)id,
+		     (void *)bip->bli_buf,
+		     (void *)((unsigned long)bip->bli_flags),
+		     (void *)((unsigned long)bip->bli_recur),
+		     (void *)((unsigned long)atomic_read(&bip->bli_refcount)),
+		     (void *)((unsigned long)
+				(0xFFFFFFFF & XFS_BUF_ADDR(bp) >> 32)),
+		     (void *)((unsigned long)(0xFFFFFFFF & XFS_BUF_ADDR(bp))),
+		     (void *)((unsigned long)XFS_BUF_COUNT(bp)),
+		     (void *)((unsigned long)XFS_BUF_BFLAGS(bp)),
+		     XFS_BUF_FSPRIVATE(bp, void *),
+		     XFS_BUF_FSPRIVATE2(bp, void *),
+		     (void *)(unsigned long)XFS_BUF_ISPINNED(bp),
+		     (void *)XFS_BUF_IODONE_FUNC(bp),
+		     (void *)((unsigned long)(XFS_BUF_VALUSEMA(bp))),
+		     (void *)bip->bli_item.li_desc,
+		     (void *)((unsigned long)bip->bli_item.li_flags));
+}
+#endif /* XFS_BLI_TRACE */
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)