Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 3560 insertions, 0 deletions

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
new file mode 100644
index 00000000000..092d5fb096b
--- /dev/null
+++ b/fs/xfs/xfs_log.c
@@ -0,0 +1,3560 @@
+/*
+ * Copyright (c) 2000-2004 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/
+ */
+
+/*
+ * High level interface routines for log manager
+ */
+
+#include "xfs.h"
+#include "xfs_macros.h"
+#include "xfs_types.h"
+#include "xfs_inum.h"
+#include "xfs_ag.h"
+#include "xfs_sb.h"
+#include "xfs_log.h"
+#include "xfs_trans.h"
+#include "xfs_dir.h"
+#include "xfs_dmapi.h"
+#include "xfs_mount.h"
+#include "xfs_error.h"
+#include "xfs_log_priv.h"
+#include "xfs_buf_item.h"
+#include "xfs_alloc_btree.h"
+#include "xfs_log_recover.h"
+#include "xfs_bit.h"
+#include "xfs_rw.h"
+#include "xfs_trans_priv.h"
+
+
+#define xlog_write_adv_cnt(ptr, len, off, bytes) \
+	{ (ptr) += (bytes); \
+	  (len) -= (bytes); \
+	  (off) += (bytes);}
+
+/* Local miscellaneous function prototypes */
+STATIC int	 xlog_bdstrat_cb(struct xfs_buf *);
+STATIC int	 xlog_commit_record(xfs_mount_t *mp, xlog_ticket_t *ticket,
+				    xlog_in_core_t **, xfs_lsn_t *);
+STATIC xlog_t *  xlog_alloc_log(xfs_mount_t	*mp,
+				xfs_buftarg_t	*log_target,
+				xfs_daddr_t	blk_offset,
+				int		num_bblks);
+STATIC int	 xlog_space_left(xlog_t *log, int cycle, int bytes);
+STATIC int	 xlog_sync(xlog_t *log, xlog_in_core_t *iclog);
+STATIC void	 xlog_unalloc_log(xlog_t *log);
+STATIC int	 xlog_write(xfs_mount_t *mp, xfs_log_iovec_t region[],
+			    int nentries, xfs_log_ticket_t tic,
+			    xfs_lsn_t *start_lsn,
+			    xlog_in_core_t **commit_iclog,
+			    uint flags);
+
+/* local state machine functions */
+STATIC void xlog_state_done_syncing(xlog_in_core_t *iclog, int);
+STATIC void xlog_state_do_callback(xlog_t *log,int aborted, xlog_in_core_t *iclog);
+STATIC int  xlog_state_get_iclog_space(xlog_t		*log,
+				       int		len,
+				       xlog_in_core_t	**iclog,
+				       xlog_ticket_t	*ticket,
+				       int		*continued_write,
+				       int		*logoffsetp);
+STATIC void xlog_state_put_ticket(xlog_t	*log,
+				  xlog_ticket_t *tic);
+STATIC int  xlog_state_release_iclog(xlog_t		*log,
+				     xlog_in_core_t	*iclog);
+STATIC void xlog_state_switch_iclogs(xlog_t		*log,
+				     xlog_in_core_t *iclog,
+				     int		eventual_size);
+STATIC int  xlog_state_sync(xlog_t *log, xfs_lsn_t lsn, uint flags);
+STATIC int  xlog_state_sync_all(xlog_t *log, uint flags);
+STATIC void xlog_state_want_sync(xlog_t	*log, xlog_in_core_t *iclog);
+
+/* local functions to manipulate grant head */
+STATIC int  xlog_grant_log_space(xlog_t		*log,
+				 xlog_ticket_t	*xtic);
+STATIC void xlog_grant_push_ail(xfs_mount_t	*mp,
+				int		need_bytes);
+STATIC void xlog_regrant_reserve_log_space(xlog_t	 *log,
+					   xlog_ticket_t *ticket);
+STATIC int xlog_regrant_write_log_space(xlog_t		*log,
+					 xlog_ticket_t  *ticket);
+STATIC void xlog_ungrant_log_space(xlog_t	 *log,
+				   xlog_ticket_t *ticket);
+
+
+/* local ticket functions */
+STATIC void		xlog_state_ticket_alloc(xlog_t *log);
+STATIC xlog_ticket_t	*xlog_ticket_get(xlog_t *log,
+					 int	unit_bytes,
+					 int	count,
+					 char	clientid,
+					 uint	flags);
+STATIC void		xlog_ticket_put(xlog_t *log, xlog_ticket_t *ticket);
+
+/* local debug functions */
+#if defined(DEBUG) && !defined(XLOG_NOLOG)
+STATIC void	xlog_verify_dest_ptr(xlog_t *log, __psint_t ptr);
+STATIC void	xlog_verify_grant_head(xlog_t *log, int equals);
+STATIC void	xlog_verify_iclog(xlog_t *log, xlog_in_core_t *iclog,
+				  int count, boolean_t syncing);
+STATIC void	xlog_verify_tail_lsn(xlog_t *log, xlog_in_core_t *iclog,
+				     xfs_lsn_t tail_lsn);
+#else
+#define xlog_verify_dest_ptr(a,b)
+#define xlog_verify_grant_head(a,b)
+#define xlog_verify_iclog(a,b,c,d)
+#define xlog_verify_tail_lsn(a,b,c)
+#endif
+
+int		xlog_iclogs_empty(xlog_t *log);
+
+#ifdef DEBUG
+int xlog_do_error = 0;
+int xlog_req_num  = 0;
+int xlog_error_mod = 33;
+#endif
+
+#define XLOG_FORCED_SHUTDOWN(log)	(log->l_flags & XLOG_IO_ERROR)
+
+/*
+ * 0 => disable log manager
+ * 1 => enable log manager
+ * 2 => enable log manager and log debugging
+ */
+#if defined(XLOG_NOLOG) || defined(DEBUG)
+int   xlog_debug = 1;
+xfs_buftarg_t *xlog_target;
+#endif
+
+#if defined(XFS_LOG_TRACE)
+
+void
+xlog_trace_loggrant(xlog_t *log, xlog_ticket_t *tic, xfs_caddr_t string)
+{
+	if (! log->l_grant_trace) {
+		log->l_grant_trace = ktrace_alloc(1024, KM_NOSLEEP);
+		if (! log->l_grant_trace)
+			return;
+	}
+
+	ktrace_enter(log->l_grant_trace,
+		     (void *)tic,
+		     (void *)log->l_reserve_headq,
+		     (void *)log->l_write_headq,
+		     (void *)((unsigned long)log->l_grant_reserve_cycle),
+		     (void *)((unsigned long)log->l_grant_reserve_bytes),
+		     (void *)((unsigned long)log->l_grant_write_cycle),
+		     (void *)((unsigned long)log->l_grant_write_bytes),
+		     (void *)((unsigned long)log->l_curr_cycle),
+		     (void *)((unsigned long)log->l_curr_block),
+		     (void *)((unsigned long)CYCLE_LSN(log->l_tail_lsn)),
+		     (void *)((unsigned long)BLOCK_LSN(log->l_tail_lsn)),
+		     (void *)string,
+		     (void *)((unsigned long)13),
+		     (void *)((unsigned long)14),
+		     (void *)((unsigned long)15),
+		     (void *)((unsigned long)16));
+}
+
+void
+xlog_trace_iclog(xlog_in_core_t *iclog, uint state)
+{
+	pid_t pid;
+
+	pid = current_pid();
+
+	if (!iclog->ic_trace)
+		iclog->ic_trace = ktrace_alloc(256, KM_SLEEP);
+	ktrace_enter(iclog->ic_trace,
+		     (void *)((unsigned long)state),
+		     (void *)((unsigned long)pid),
+		     (void *)0,
+		     (void *)0,
+		     (void *)0,
+		     (void *)0,
+		     (void *)0,
+		     (void *)0,
+		     (void *)0,
+		     (void *)0,
+		     (void *)0,
+		     (void *)0,
+		     (void *)0,
+		     (void *)0,
+		     (void *)0,
+		     (void *)0);
+}
+
+#else
+#define	xlog_trace_loggrant(log,tic,string)
+#define	xlog_trace_iclog(iclog,state)
+#endif /* XFS_LOG_TRACE */
+
+/*
+ * NOTES:
+ *
+ *	1. currblock field gets updated at startup and after in-core logs
+ *		marked as with WANT_SYNC.
+ */
+
+/*
+ * This routine is called when a user of a log manager ticket is done with
+ * the reservation.  If the ticket was ever used, then a commit record for
+ * the associated transaction is written out as a log operation header with
+ * no data.  The flag XLOG_TIC_INITED is set when the first write occurs with
+ * a given ticket.  If the ticket was one with a permanent reservation, then
+ * a few operations are done differently.  Permanent reservation tickets by
+ * default don't release the reservation.  They just commit the current
+ * transaction with the belief that the reservation is still needed.  A flag
+ * must be passed in before permanent reservations are actually released.
+ * When these type of tickets are not released, they need to be set into
+ * the inited state again.  By doing this, a start record will be written
+ * out when the next write occurs.
+ */
+xfs_lsn_t
+xfs_log_done(xfs_mount_t	*mp,
+	     xfs_log_ticket_t	xtic,
+	     void		**iclog,
+	     uint		flags)
+{
+	xlog_t		*log    = mp->m_log;
+	xlog_ticket_t	*ticket = (xfs_log_ticket_t) xtic;
+	xfs_lsn_t	lsn	= 0;
+
+#if defined(DEBUG) || defined(XLOG_NOLOG)
+	if (!xlog_debug && xlog_target == log->l_targ)
+		return 0;
+#endif
+
+	if (XLOG_FORCED_SHUTDOWN(log) ||
+	    /*
+	     * If nothing was ever written, don't write out commit record.
+	     * If we get an error, just continue and give back the log ticket.
+	     */
+	    (((ticket->t_flags & XLOG_TIC_INITED) == 0) &&
+	     (xlog_commit_record(mp, ticket,
+				 (xlog_in_core_t **)iclog, &lsn)))) {
+		lsn = (xfs_lsn_t) -1;
+		if (ticket->t_flags & XLOG_TIC_PERM_RESERV) {
+			flags |= XFS_LOG_REL_PERM_RESERV;
+		}
+	}
+
+
+	if ((ticket->t_flags & XLOG_TIC_PERM_RESERV) == 0 ||
+	    (flags & XFS_LOG_REL_PERM_RESERV)) {
+		/*
+		 * Release ticket if not permanent reservation or a specifc
+		 * request has been made to release a permanent reservation.
+		 */
+		xlog_ungrant_log_space(log, ticket);
+		xlog_state_put_ticket(log, ticket);
+	} else {
+		xlog_regrant_reserve_log_space(log, ticket);
+	}
+
+	/* If this ticket was a permanent reservation and we aren't
+	 * trying to release it, reset the inited flags; so next time
+	 * we write, a start record will be written out.
+	 */
+	if ((ticket->t_flags & XLOG_TIC_PERM_RESERV) &&
+	    (flags & XFS_LOG_REL_PERM_RESERV) == 0)
+		ticket->t_flags |= XLOG_TIC_INITED;
+
+	return lsn;
+}	/* xfs_log_done */
+
+
+/*
+ * Force the in-core log to disk.  If flags == XFS_LOG_SYNC,
+ *	the force is done synchronously.
+ *
+ * Asynchronous forces are implemented by setting the WANT_SYNC
+ * bit in the appropriate in-core log and then returning.
+ *
+ * Synchronous forces are implemented with a semaphore.  All callers
+ * to force a given lsn to disk will wait on a semaphore attached to the
+ * specific in-core log.  When given in-core log finally completes its
+ * write to disk, that thread will wake up all threads waiting on the
+ * semaphore.
+ */
+int
+xfs_log_force(xfs_mount_t *mp,
+	      xfs_lsn_t	  lsn,
+	      uint	  flags)
+{
+	int	rval;
+	xlog_t *log = mp->m_log;
+
+#if defined(DEBUG) || defined(XLOG_NOLOG)
+	if (!xlog_debug && xlog_target == log->l_targ)
+		return 0;
+#endif
+
+	ASSERT(flags & XFS_LOG_FORCE);
+
+	XFS_STATS_INC(xs_log_force);
+
+	if ((log->l_flags & XLOG_IO_ERROR) == 0) {
+		if (lsn == 0)
+			rval = xlog_state_sync_all(log, flags);
+		else
+			rval = xlog_state_sync(log, lsn, flags);
+	} else {
+		rval = XFS_ERROR(EIO);
+	}
+
+	return rval;
+
+}	/* xfs_log_force */
+
+/*
+ * Attaches a new iclog I/O completion callback routine during
+ * transaction commit.  If the log is in error state, a non-zero
+ * return code is handed back and the caller is responsible for
+ * executing the callback at an appropriate time.
+ */
+int
+xfs_log_notify(xfs_mount_t	  *mp,		/* mount of partition */
+	       void		  *iclog_hndl,	/* iclog to hang callback off */
+	       xfs_log_callback_t *cb)
+{
+	xlog_t *log = mp->m_log;
+	xlog_in_core_t	  *iclog = (xlog_in_core_t *)iclog_hndl;
+	int	abortflg, spl;
+
+#if defined(DEBUG) || defined(XLOG_NOLOG)
+	if (!xlog_debug && xlog_target == log->l_targ)
+		return 0;
+#endif
+	cb->cb_next = NULL;
+	spl = LOG_LOCK(log);
+	abortflg = (iclog->ic_state & XLOG_STATE_IOERROR);
+	if (!abortflg) {
+		ASSERT_ALWAYS((iclog->ic_state == XLOG_STATE_ACTIVE) ||
+			      (iclog->ic_state == XLOG_STATE_WANT_SYNC));
+		cb->cb_next = NULL;
+		*(iclog->ic_callback_tail) = cb;
+		iclog->ic_callback_tail = &(cb->cb_next);
+	}
+	LOG_UNLOCK(log, spl);
+	return abortflg;
+}	/* xfs_log_notify */
+
+int
+xfs_log_release_iclog(xfs_mount_t *mp,
+		      void	  *iclog_hndl)
+{
+	xlog_t *log = mp->m_log;
+	xlog_in_core_t	  *iclog = (xlog_in_core_t *)iclog_hndl;
+
+	if (xlog_state_release_iclog(log, iclog)) {
+		xfs_force_shutdown(mp, XFS_LOG_IO_ERROR);
+		return(EIO);
+	}
+
+	return 0;
+}
+
+/*
+ *  1. Reserve an amount of on-disk log space and return a ticket corresponding
+ *	to the reservation.
+ *  2. Potentially, push buffers at tail of log to disk.
+ *
+ * Each reservation is going to reserve extra space for a log record header.
+ * When writes happen to the on-disk log, we don't subtract the length of the
+ * log record header from any reservation.  By wasting space in each
+ * reservation, we prevent over allocation problems.
+ */
+int
+xfs_log_reserve(xfs_mount_t	 *mp,
+		int		 unit_bytes,
+		int		 cnt,
+		xfs_log_ticket_t *ticket,
+		__uint8_t	 client,
+		uint		 flags)
+{
+	xlog_t		*log = mp->m_log;
+	xlog_ticket_t	*internal_ticket;
+	int		retval;
+
+#if defined(DEBUG) || defined(XLOG_NOLOG)
+	if (!xlog_debug && xlog_target == log->l_targ)
+		return 0;
+#endif
+	retval = 0;
+	ASSERT(client == XFS_TRANSACTION || client == XFS_LOG);
+	ASSERT((flags & XFS_LOG_NOSLEEP) == 0);
+
+	if (XLOG_FORCED_SHUTDOWN(log))
+		return XFS_ERROR(EIO);
+
+	XFS_STATS_INC(xs_try_logspace);
+
+	if (*ticket != NULL) {
+		ASSERT(flags & XFS_LOG_PERM_RESERV);
+		internal_ticket = (xlog_ticket_t *)*ticket;
+		xlog_grant_push_ail(mp, internal_ticket->t_unit_res);
+		retval = xlog_regrant_write_log_space(log, internal_ticket);
+	} else {
+		/* may sleep if need to allocate more tickets */
+		internal_ticket = xlog_ticket_get(log, unit_bytes, cnt,
+						  client, flags);
+		*ticket = internal_ticket;
+		xlog_grant_push_ail(mp,
+				    (internal_ticket->t_unit_res *
+				     internal_ticket->t_cnt));
+		retval = xlog_grant_log_space(log, internal_ticket);
+	}
+
+	return retval;
+}	/* xfs_log_reserve */
+
+
+/*
+ * Mount a log filesystem
+ *
+ * mp		- ubiquitous xfs mount point structure
+ * log_target	- buftarg of on-disk log device
+ * blk_offset	- Start block # where block size is 512 bytes (BBSIZE)
+ * num_bblocks	- Number of BBSIZE blocks in on-disk log
+ *
+ * Return error or zero.
+ */
+int
+xfs_log_mount(xfs_mount_t	*mp,
+	      xfs_buftarg_t	*log_target,
+	      xfs_daddr_t	blk_offset,
+	      int		num_bblks)
+{
+	if (!(mp->m_flags & XFS_MOUNT_NORECOVERY))
+		cmn_err(CE_NOTE, "XFS mounting filesystem %s", mp->m_fsname);
+	else {
+		cmn_err(CE_NOTE,
+			"!Mounting filesystem \"%s\" in no-recovery mode.  Filesystem will be inconsistent.",
+			mp->m_fsname);
+		ASSERT(XFS_MTOVFS(mp)->vfs_flag & VFS_RDONLY);
+	}
+
+	mp->m_log = xlog_alloc_log(mp, log_target, blk_offset, num_bblks);
+
+#if defined(DEBUG) || defined(XLOG_NOLOG)
+	if (!xlog_debug) {
+		cmn_err(CE_NOTE, "log dev: %s", XFS_BUFTARG_NAME(log_target));
+		return 0;
+	}
+#endif
+	/*
+	 * skip log recovery on a norecovery mount.  pretend it all
+	 * just worked.
+	 */
+	if (!(mp->m_flags & XFS_MOUNT_NORECOVERY)) {
+		int	error;
+		vfs_t	*vfsp = XFS_MTOVFS(mp);
+		int	readonly = (vfsp->vfs_flag & VFS_RDONLY);
+
+		if (readonly)
+			vfsp->vfs_flag &= ~VFS_RDONLY;
+
+		error = xlog_recover(mp->m_log, readonly);
+
+		if (readonly)
+			vfsp->vfs_flag |= VFS_RDONLY;
+		if (error) {
+			cmn_err(CE_WARN, "XFS: log mount/recovery failed: error %d", error);
+			xlog_unalloc_log(mp->m_log);
+			return error;
+		}
+	}
+
+	/* Normal transactions can now occur */
+	mp->m_log->l_flags &= ~XLOG_ACTIVE_RECOVERY;
+
+	/* End mounting message in xfs_log_mount_finish */
+	return 0;
+}	/* xfs_log_mount */
+
+/*
+ * Finish the recovery of the file system.  This is separate from
+ * the xfs_log_mount() call, because it depends on the code in
+ * xfs_mountfs() to read in the root and real-time bitmap inodes
+ * between calling xfs_log_mount() and here.
+ *
+ * mp		- ubiquitous xfs mount point structure
+ */
+int
+xfs_log_mount_finish(xfs_mount_t *mp, int mfsi_flags)
+{
+	int	error;
+
+	if (!(mp->m_flags & XFS_MOUNT_NORECOVERY))
+		error = xlog_recover_finish(mp->m_log, mfsi_flags);
+	else {
+		error = 0;
+		ASSERT(XFS_MTOVFS(mp)->vfs_flag & VFS_RDONLY);
+	}
+
+	return error;
+}
+
+/*
+ * Unmount processing for the log.
+ */
+int
+xfs_log_unmount(xfs_mount_t *mp)
+{
+	int		error;
+
+	error = xfs_log_unmount_write(mp);
+	xfs_log_unmount_dealloc(mp);
+	return (error);
+}
+
+/*
+ * Final log writes as part of unmount.
+ *
+ * Mark the filesystem clean as unmount happens.  Note that during relocation
+ * this routine needs to be executed as part of source-bag while the
+ * deallocation must not be done until source-end.
+ */
+
+/*
+ * Unmount record used to have a string "Unmount filesystem--" in the
+ * data section where the "Un" was really a magic number (XLOG_UNMOUNT_TYPE).
+ * We just write the magic number now since that particular field isn't
+ * currently architecture converted and "nUmount" is a bit foo.
+ * As far as I know, there weren't any dependencies on the old behaviour.
+ */
+
+int
+xfs_log_unmount_write(xfs_mount_t *mp)
+{
+	xlog_t		 *log = mp->m_log;
+	xlog_in_core_t	 *iclog;
+#ifdef DEBUG
+	xlog_in_core_t	 *first_iclog;
+#endif
+	xfs_log_iovec_t  reg[1];
+	xfs_log_ticket_t tic = NULL;
+	xfs_lsn_t	 lsn;
+	int		 error;
+	SPLDECL(s);
+
+	/* the data section must be 32 bit size aligned */
+	struct {
+	    __uint16_t magic;
+	    __uint16_t pad1;
+	    __uint32_t pad2; /* may as well make it 64 bits */
+	} magic = { XLOG_UNMOUNT_TYPE, 0, 0 };
+
+#if defined(DEBUG) || defined(XLOG_NOLOG)
+	if (!xlog_debug && xlog_target == log->l_targ)
+		return 0;
+#endif
+
+	/*
+	 * Don't write out unmount record on read-only mounts.
+	 * Or, if we are doing a forced umount (typically because of IO errors).
+	 */
+	if (XFS_MTOVFS(mp)->vfs_flag & VFS_RDONLY)
+		return 0;
+
+	xfs_log_force(mp, 0, XFS_LOG_FORCE|XFS_LOG_SYNC);
+
+#ifdef DEBUG
+	first_iclog = iclog = log->l_iclog;
+	do {
+		if (!(iclog->ic_state & XLOG_STATE_IOERROR)) {
+			ASSERT(iclog->ic_state & XLOG_STATE_ACTIVE);
+			ASSERT(iclog->ic_offset == 0);
+		}
+		iclog = iclog->ic_next;
+	} while (iclog != first_iclog);
+#endif
+	if (! (XLOG_FORCED_SHUTDOWN(log))) {
+		reg[0].i_addr = (void*)&magic;
+		reg[0].i_len  = sizeof(magic);
+
+		error = xfs_log_reserve(mp, 600, 1, &tic, XFS_LOG, 0);
+		if (!error) {
+			/* remove inited flag */
+			((xlog_ticket_t *)tic)->t_flags = 0;
+			error = xlog_write(mp, reg, 1, tic, &lsn,
+					   NULL, XLOG_UNMOUNT_TRANS);
+			/*
+			 * At this point, we're umounting anyway,
+			 * so there's no point in transitioning log state
+			 * to IOERROR. Just continue...
+			 */
+		}
+
+		if (error) {
+			xfs_fs_cmn_err(CE_ALERT, mp,
+				"xfs_log_unmount: unmount record failed");
+		}
+
+
+		s = LOG_LOCK(log);
+		iclog = log->l_iclog;
+		iclog->ic_refcnt++;
+		LOG_UNLOCK(log, s);
+		xlog_state_want_sync(log, iclog);
+		(void) xlog_state_release_iclog(log, iclog);
+
+		s = LOG_LOCK(log);
+		if (!(iclog->ic_state == XLOG_STATE_ACTIVE ||
+		      iclog->ic_state == XLOG_STATE_DIRTY)) {
+			if (!XLOG_FORCED_SHUTDOWN(log)) {
+				sv_wait(&iclog->ic_forcesema, PMEM,
+					&log->l_icloglock, s);
+			} else {
+				LOG_UNLOCK(log, s);
+			}
+		} else {
+			LOG_UNLOCK(log, s);
+		}
+		if (tic)
+			xlog_state_put_ticket(log, tic);
+	} else {
+		/*
+		 * We're already in forced_shutdown mode, couldn't
+		 * even attempt to write out the unmount transaction.
+		 *
+		 * Go through the motions of sync'ing and releasing
+		 * the iclog, even though no I/O will actually happen,
+		 * we need to wait for other log I/O's that may already
+		 * be in progress.  Do this as a separate section of
+		 * code so we'll know if we ever get stuck here that
+		 * we're in this odd situation of trying to unmount
+		 * a file system that went into forced_shutdown as
+		 * the result of an unmount..
+		 */
+		s = LOG_LOCK(log);
+		iclog = log->l_iclog;
+		iclog->ic_refcnt++;
+		LOG_UNLOCK(log, s);
+
+		xlog_state_want_sync(log, iclog);
+		(void) xlog_state_release_iclog(log, iclog);
+
+		s = LOG_LOCK(log);
+
+		if ( ! (   iclog->ic_state == XLOG_STATE_ACTIVE
+			|| iclog->ic_state == XLOG_STATE_DIRTY
+			|| iclog->ic_state == XLOG_STATE_IOERROR) ) {
+
+				sv_wait(&iclog->ic_forcesema, PMEM,
+					&log->l_icloglock, s);
+		} else {
+			LOG_UNLOCK(log, s);
+		}
+	}
+
+	return 0;
+}	/* xfs_log_unmount_write */
+
+/*
+ * Deallocate log structures for unmount/relocation.
+ */
+void
+xfs_log_unmount_dealloc(xfs_mount_t *mp)
+{
+	xlog_unalloc_log(mp->m_log);
+}
+
+/*
+ * Write region vectors to log.  The write happens using the space reservation
+ * of the ticket (tic).  It is not a requirement that all writes for a given
+ * transaction occur with one call to xfs_log_write().
+ */
+int
+xfs_log_write(xfs_mount_t *	mp,
+	      xfs_log_iovec_t	reg[],
+	      int		nentries,
+	      xfs_log_ticket_t	tic,
+	      xfs_lsn_t		*start_lsn)
+{
+	int	error;
+	xlog_t *log = mp->m_log;
+
+#if defined(DEBUG) || defined(XLOG_NOLOG)
+	if (!xlog_debug && xlog_target == log->l_targ) {
+		*start_lsn = 0;
+		return 0;
+	}
+#endif
+	if (XLOG_FORCED_SHUTDOWN(log))
+		return XFS_ERROR(EIO);
+
+	if ((error = xlog_write(mp, reg, nentries, tic, start_lsn, NULL, 0))) {
+		xfs_force_shutdown(mp, XFS_LOG_IO_ERROR);
+	}
+	return (error);
+}	/* xfs_log_write */
+
+
+void
+xfs_log_move_tail(xfs_mount_t	*mp,
+		  xfs_lsn_t	tail_lsn)
+{
+	xlog_ticket_t	*tic;
+	xlog_t		*log = mp->m_log;
+	int		need_bytes, free_bytes, cycle, bytes;
+	SPLDECL(s);
+
+#if defined(DEBUG) || defined(XLOG_NOLOG)
+	if (!xlog_debug && xlog_target == log->l_targ)
+		return;
+#endif
+	/* XXXsup tmp */
+	if (XLOG_FORCED_SHUTDOWN(log))
+		return;
+	ASSERT(!XFS_FORCED_SHUTDOWN(mp));
+
+	if (tail_lsn == 0) {
+		/* needed since sync_lsn is 64 bits */
+		s = LOG_LOCK(log);
+		tail_lsn = log->l_last_sync_lsn;
+		LOG_UNLOCK(log, s);
+	}
+
+	s = GRANT_LOCK(log);
+
+	/* Also an invalid lsn.  1 implies that we aren't passing in a valid
+	 * tail_lsn.
+	 */
+	if (tail_lsn != 1) {
+		log->l_tail_lsn = tail_lsn;
+	}
+
+	if ((tic = log->l_write_headq)) {
+#ifdef DEBUG
+		if (log->l_flags & XLOG_ACTIVE_RECOVERY)
+			panic("Recovery problem");
+#endif
+		cycle = log->l_grant_write_cycle;
+		bytes = log->l_grant_write_bytes;
+		free_bytes = xlog_space_left(log, cycle, bytes);
+		do {
+			ASSERT(tic->t_flags & XLOG_TIC_PERM_RESERV);
+
+			if (free_bytes < tic->t_unit_res && tail_lsn != 1)
+				break;
+			tail_lsn = 0;
+			free_bytes -= tic->t_unit_res;
+			sv_signal(&tic->t_sema);
+			tic = tic->t_next;
+		} while (tic != log->l_write_headq);
+	}
+	if ((tic = log->l_reserve_headq)) {
+#ifdef DEBUG
+		if (log->l_flags & XLOG_ACTIVE_RECOVERY)
+			panic("Recovery problem");
+#endif
+		cycle = log->l_grant_reserve_cycle;
+		bytes = log->l_grant_reserve_bytes;
+		free_bytes = xlog_space_left(log, cycle, bytes);
+		do {
+			if (tic->t_flags & XLOG_TIC_PERM_RESERV)
+				need_bytes = tic->t_unit_res*tic->t_cnt;
+			else
+				need_bytes = tic->t_unit_res;
+			if (free_bytes < need_bytes && tail_lsn != 1)
+				break;
+			tail_lsn = 0;
+			free_bytes -= need_bytes;
+			sv_signal(&tic->t_sema);
+			tic = tic->t_next;
+		} while (tic != log->l_reserve_headq);
+	}
+	GRANT_UNLOCK(log, s);
+}	/* xfs_log_move_tail */
+
+/*
+ * Determine if we have a transaction that has gone to disk
+ * that needs to be covered. Log activity needs to be idle (no AIL and
+ * nothing in the iclogs). And, we need to be in the right state indicating
+ * something has gone out.
+ */
+int
+xfs_log_need_covered(xfs_mount_t *mp)
+{
+	SPLDECL(s);
+	int		needed = 0, gen;
+	xlog_t		*log = mp->m_log;
+	vfs_t		*vfsp = XFS_MTOVFS(mp);
+
+	if (fs_frozen(vfsp) || XFS_FORCED_SHUTDOWN(mp) ||
+	    (vfsp->vfs_flag & VFS_RDONLY))
+		return 0;
+
+	s = LOG_LOCK(log);
+	if (((log->l_covered_state == XLOG_STATE_COVER_NEED) ||
+		(log->l_covered_state == XLOG_STATE_COVER_NEED2))
+			&& !xfs_trans_first_ail(mp, &gen)
+			&& xlog_iclogs_empty(log)) {
+		if (log->l_covered_state == XLOG_STATE_COVER_NEED)
+			log->l_covered_state = XLOG_STATE_COVER_DONE;
+		else {
+			ASSERT(log->l_covered_state == XLOG_STATE_COVER_NEED2);
+			log->l_covered_state = XLOG_STATE_COVER_DONE2;
+		}
+		needed = 1;
+	}
+	LOG_UNLOCK(log, s);
+	return(needed);
+}
+
+/******************************************************************************
+ *
+ *	local routines
+ *
+ ******************************************************************************
+ */
+
+/* xfs_trans_tail_ail returns 0 when there is nothing in the list.
+ * The log manager must keep track of the last LR which was committed
+ * to disk.  The lsn of this LR will become the new tail_lsn whenever
+ * xfs_trans_tail_ail returns 0.  If we don't do this, we run into
+ * the situation where stuff could be written into the log but nothing
+ * was ever in the AIL when asked.  Eventually, we panic since the
+ * tail hits the head.
+ *
+ * We may be holding the log iclog lock upon entering this routine.
+ */
+xfs_lsn_t
+xlog_assign_tail_lsn(xfs_mount_t *mp)
+{
+	xfs_lsn_t tail_lsn;
+	SPLDECL(s);
+	xlog_t	  *log = mp->m_log;
+
+	tail_lsn = xfs_trans_tail_ail(mp);
+	s = GRANT_LOCK(log);
+	if (tail_lsn != 0) {
+		log->l_tail_lsn = tail_lsn;
+	} else {
+		tail_lsn = log->l_tail_lsn = log->l_last_sync_lsn;
+	}
+	GRANT_UNLOCK(log, s);
+
+	return tail_lsn;
+}	/* xlog_assign_tail_lsn */
+
+
+/*
+ * Return the space in the log between the tail and the head.  The head
+ * is passed in the cycle/bytes formal parms.  In the special case where
+ * the reserve head has wrapped passed the tail, this calculation is no
+ * longer valid.  In this case, just return 0 which means there is no space
+ * in the log.  This works for all places where this function is called
+ * with the reserve head.  Of course, if the write head were to ever
+ * wrap the tail, we should blow up.  Rather than catch this case here,
+ * we depend on other ASSERTions in other parts of the code.   XXXmiken
+ *
+ * This code also handles the case where the reservation head is behind
+ * the tail.  The details of this case are described below, but the end
+ * result is that we return the size of the log as the amount of space left.
+ */
+int
+xlog_space_left(xlog_t *log, int cycle, int bytes)
+{
+	int free_bytes;
+	int tail_bytes;
+	int tail_cycle;
+
+	tail_bytes = BBTOB(BLOCK_LSN(log->l_tail_lsn));
+	tail_cycle = CYCLE_LSN(log->l_tail_lsn);
+	if ((tail_cycle == cycle) && (bytes >= tail_bytes)) {
+		free_bytes = log->l_logsize - (bytes - tail_bytes);
+	} else if ((tail_cycle + 1) < cycle) {
+		return 0;
+	} else if (tail_cycle < cycle) {
+		ASSERT(tail_cycle == (cycle - 1));
+		free_bytes = tail_bytes - bytes;
+	} else {
+		/*
+		 * The reservation head is behind the tail.
+		 * In this case we just want to return the size of the
+		 * log as the amount of space left.
+		 */
+		xfs_fs_cmn_err(CE_ALERT, log->l_mp,
+			"xlog_space_left: head behind tail\n"
+			"  tail_cycle = %d, tail_bytes = %d\n"
+			"  GH   cycle = %d, GH   bytes = %d",
+			tail_cycle, tail_bytes, cycle, bytes);
+		ASSERT(0);
+		free_bytes = log->l_logsize;
+	}
+	return free_bytes;
+}	/* xlog_space_left */
+
+
+/*
+ * Log function which is called when an io completes.
+ *
+ * The log manager needs its own routine, in order to control what
+ * happens with the buffer after the write completes.
+ */
+void
+xlog_iodone(xfs_buf_t *bp)
+{
+	xlog_in_core_t	*iclog;
+	xlog_t		*l;
+	int		aborted;
+
+	iclog = XFS_BUF_FSPRIVATE(bp, xlog_in_core_t *);
+	ASSERT(XFS_BUF_FSPRIVATE2(bp, unsigned long) == (unsigned long) 2);
+	XFS_BUF_SET_FSPRIVATE2(bp, (unsigned long)1);
+	aborted = 0;
+
+	/*
+	 * Some versions of cpp barf on the recursive definition of
+	 * ic_log -> hic_fields.ic_log and expand ic_log twice when
+	 * it is passed through two macros.  Workaround broken cpp.
+	 */
+	l = iclog->ic_log;
+
+	/*
+	 * Race to shutdown the filesystem if we see an error.
+	 */
+	if (XFS_TEST_ERROR((XFS_BUF_GETERROR(bp)), l->l_mp,
+			XFS_ERRTAG_IODONE_IOERR, XFS_RANDOM_IODONE_IOERR)) {
+		xfs_ioerror_alert("xlog_iodone", l->l_mp, bp, XFS_BUF_ADDR(bp));
+		XFS_BUF_STALE(bp);
+		xfs_force_shutdown(l->l_mp, XFS_LOG_IO_ERROR);
+		/*
+		 * This flag will be propagated to the trans-committed
+		 * callback routines to let them know that the log-commit
+		 * didn't succeed.
+		 */
+		aborted = XFS_LI_ABORTED;
+	} else if (iclog->ic_state & XLOG_STATE_IOERROR) {
+		aborted = XFS_LI_ABORTED;
+	}
+	xlog_state_done_syncing(iclog, aborted);
+	if (!(XFS_BUF_ISASYNC(bp))) {
+		/*
+		 * Corresponding psema() will be done in bwrite().  If we don't
+		 * vsema() here, panic.
+		 */
+		XFS_BUF_V_IODONESEMA(bp);
+	}
+}	/* xlog_iodone */
+
+/*
+ * The bdstrat callback function for log bufs. This gives us a central
+ * place to trap bufs in case we get hit by a log I/O error and need to
+ * shutdown. Actually, in practice, even when we didn't get a log error,
+ * we transition the iclogs to IOERROR state *after* flushing all existing
+ * iclogs to disk. This is because we don't want anymore new transactions to be
+ * started or completed afterwards.
+ */
+STATIC int
+xlog_bdstrat_cb(struct xfs_buf *bp)
+{
+	xlog_in_core_t *iclog;
+
+	iclog = XFS_BUF_FSPRIVATE(bp, xlog_in_core_t *);
+
+	if ((iclog->ic_state & XLOG_STATE_IOERROR) == 0) {
+	  /* note for irix bstrat will need  struct bdevsw passed
+	   * Fix the following macro if the code ever is merged
+	   */
+	    XFS_bdstrat(bp);
+		return 0;
+	}
+
+	xfs_buftrace("XLOG__BDSTRAT IOERROR", bp);
+	XFS_BUF_ERROR(bp, EIO);
+	XFS_BUF_STALE(bp);
+	xfs_biodone(bp);
+	return (XFS_ERROR(EIO));
+
+
+}
+
+/*
+ * Return size of each in-core log record buffer.
+ *
+ * Low memory machines only get 2 16KB buffers.  We don't want to waste
+ * memory here.  However, all other machines get at least 2 32KB buffers.
+ * The number is hard coded because we don't care about the minimum
+ * memory size, just 32MB systems.
+ *
+ * If the filesystem blocksize is too large, we may need to choose a
+ * larger size since the directory code currently logs entire blocks.
+ */
+
+STATIC void
+xlog_get_iclog_buffer_size(xfs_mount_t	*mp,
+			   xlog_t	*log)
+{
+	int size;
+	int xhdrs;
+
+#if defined(DEBUG) || defined(XLOG_NOLOG)
+	/*
+	 * When logbufs == 0, someone has disabled the log from the FSTAB
+	 * file.  This is not a documented feature.  We need to set xlog_debug
+	 * to zero (this deactivates the log) and set xlog_target to the
+	 * appropriate device.  Only one filesystem may be affected as such
+	 * since this is just a performance hack to test what we might be able
+	 * to get if the log were not present.
+	 */
+	if (mp->m_logbufs == 0) {
+		xlog_debug = 0;
+		xlog_target = log->l_targ;
+		log->l_iclog_bufs = XLOG_MIN_ICLOGS;
+	} else
+#endif
+	{
+		/*
+		 * This is the normal path.  If m_logbufs == -1, then the
+		 * admin has chosen to use the system defaults for logbuffers.
+		 */
+		if (mp->m_logbufs == -1) { 
+			if (xfs_physmem <= btoc(128*1024*1024)) { 
+				log->l_iclog_bufs = XLOG_MIN_ICLOGS; 
+			} else if (xfs_physmem <= btoc(400*1024*1024)) { 
+				log->l_iclog_bufs = XLOG_MED_ICLOGS; 
+			} else {
+				/* 256K with 32K bufs */
+				log->l_iclog_bufs = XLOG_MAX_ICLOGS;
+			}
+		} else
+			log->l_iclog_bufs = mp->m_logbufs;
+
+#if defined(DEBUG) || defined(XLOG_NOLOG)
+		/* We are reactivating a filesystem after it was inactive */
+		if (log->l_targ == xlog_target) {
+			xlog_target = NULL;
+			xlog_debug = 1;
+		}
+#endif
+	}
+
+	/*
+	 * Buffer size passed in from mount system call.
+	 */
+	if (mp->m_logbsize != -1) {
+		size = log->l_iclog_size = mp->m_logbsize;
+		log->l_iclog_size_log = 0;
+		while (size != 1) {
+			log->l_iclog_size_log++;
+			size >>= 1;
+		}
+
+		if (XFS_SB_VERSION_HASLOGV2(&mp->m_sb)) {
+			/* # headers = size / 32K
+			 * one header holds cycles from 32K of data
+			 */
+
+			xhdrs = mp->m_logbsize / XLOG_HEADER_CYCLE_SIZE;
+			if (mp->m_logbsize % XLOG_HEADER_CYCLE_SIZE)
+				xhdrs++;
+			log->l_iclog_hsize = xhdrs << BBSHIFT;
+			log->l_iclog_heads = xhdrs;
+		} else {
+			ASSERT(mp->m_logbsize <= XLOG_BIG_RECORD_BSIZE);
+			log->l_iclog_hsize = BBSIZE;
+			log->l_iclog_heads = 1;
+		}
+		return;
+	}
+
+	/*
+	 * Special case machines that have less than 32MB of memory.
+	 * All machines with more memory use 32KB buffers.
+	 */
+	if (xfs_physmem <= btoc(32*1024*1024)) {
+		/* Don't change; min configuration */
+		log->l_iclog_size = XLOG_RECORD_BSIZE;		/* 16k */
+		log->l_iclog_size_log = XLOG_RECORD_BSHIFT;
+	} else {
+		log->l_iclog_size = XLOG_BIG_RECORD_BSIZE;	/* 32k */
+		log->l_iclog_size_log = XLOG_BIG_RECORD_BSHIFT;
+	}
+
+	/* the default log size is 16k or 32k which is one header sector */
+	log->l_iclog_hsize = BBSIZE;
+	log->l_iclog_heads = 1;
+
+	/*
+	 * For 16KB, we use 3 32KB buffers.  For 32KB block sizes, we use
+	 * 4 32KB buffers.  For 64KB block sizes, we use 8 32KB buffers.
+	 */
+	if (mp->m_sb.sb_blocksize >= 16*1024) {
+		log->l_iclog_size = XLOG_BIG_RECORD_BSIZE;
+		log->l_iclog_size_log = XLOG_BIG_RECORD_BSHIFT;
+		if (mp->m_logbufs == -1) {
+			switch (mp->m_sb.sb_blocksize) {
+			    case 16*1024:			/* 16 KB */
+				log->l_iclog_bufs = 3;
+				break;
+			    case 32*1024:			/* 32 KB */
+				log->l_iclog_bufs = 4;
+				break;
+			    case 64*1024:			/* 64 KB */
+				log->l_iclog_bufs = 8;
+				break;
+			    default:
+				xlog_panic("XFS: Invalid blocksize");
+				break;
+			}
+		}
+	}
+}	/* xlog_get_iclog_buffer_size */
+
+
+/*
+ * This routine initializes some of the log structure for a given mount point.
+ * Its primary purpose is to fill in enough, so recovery can occur.  However,
+ * some other stuff may be filled in too.
+ */
+STATIC xlog_t *
+xlog_alloc_log(xfs_mount_t	*mp,
+	       xfs_buftarg_t	*log_target,
+	       xfs_daddr_t	blk_offset,
+	       int		num_bblks)
+{
+	xlog_t			*log;
+	xlog_rec_header_t	*head;
+	xlog_in_core_t		**iclogp;
+	xlog_in_core_t		*iclog, *prev_iclog=NULL;
+	xfs_buf_t		*bp;
+	int			i;
+	int			iclogsize;
+
+	log = (xlog_t *)kmem_zalloc(sizeof(xlog_t), KM_SLEEP);
+
+	log->l_mp	   = mp;
+	log->l_targ	   = log_target;
+	log->l_logsize     = BBTOB(num_bblks);
+	log->l_logBBstart  = blk_offset;
+	log->l_logBBsize   = num_bblks;
+	log->l_covered_state = XLOG_STATE_COVER_IDLE;
+	log->l_flags	   |= XLOG_ACTIVE_RECOVERY;
+
+	log->l_prev_block  = -1;
+	ASSIGN_ANY_LSN_HOST(log->l_tail_lsn, 1, 0);
+	/* log->l_tail_lsn = 0x100000000LL; cycle = 1; current block = 0 */
+	log->l_last_sync_lsn = log->l_tail_lsn;
+	log->l_curr_cycle  = 1;	    /* 0 is bad since this is initial value */
+	log->l_grant_reserve_cycle = 1;
+	log->l_grant_write_cycle = 1;
+
+	if (XFS_SB_VERSION_HASSECTOR(&mp->m_sb)) {
+		log->l_sectbb_log = mp->m_sb.sb_logsectlog - BBSHIFT;
+		ASSERT(log->l_sectbb_log <= mp->m_sectbb_log);
+		/* for larger sector sizes, must have v2 or external log */
+		ASSERT(log->l_sectbb_log == 0 ||
+			log->l_logBBstart == 0 ||
+			XFS_SB_VERSION_HASLOGV2(&mp->m_sb));
+		ASSERT(mp->m_sb.sb_logsectlog >= BBSHIFT);
+	}
+	log->l_sectbb_mask = (1 << log->l_sectbb_log) - 1;
+
+	xlog_get_iclog_buffer_size(mp, log);
+
+	bp = xfs_buf_get_empty(log->l_iclog_size, mp->m_logdev_targp);
+	XFS_BUF_SET_IODONE_FUNC(bp, xlog_iodone);
+	XFS_BUF_SET_BDSTRAT_FUNC(bp, xlog_bdstrat_cb);
+	XFS_BUF_SET_FSPRIVATE2(bp, (unsigned long)1);
+	ASSERT(XFS_BUF_ISBUSY(bp));
+	ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
+	log->l_xbuf = bp;
+
+	spinlock_init(&log->l_icloglock, "iclog");
+	spinlock_init(&log->l_grant_lock, "grhead_iclog");
+	initnsema(&log->l_flushsema, 0, "ic-flush");
+	xlog_state_ticket_alloc(log);  /* wait until after icloglock inited */
+
+	/* log record size must be multiple of BBSIZE; see xlog_rec_header_t */
+	ASSERT((XFS_BUF_SIZE(bp) & BBMASK) == 0);
+
+	iclogp = &log->l_iclog;
+	/*
+	 * The amount of memory to allocate for the iclog structure is
+	 * rather funky due to the way the structure is defined.  It is
+	 * done this way so that we can use different sizes for machines
+	 * with different amounts of memory.  See the definition of
+	 * xlog_in_core_t in xfs_log_priv.h for details.
+	 */
+	iclogsize = log->l_iclog_size;
+	ASSERT(log->l_iclog_size >= 4096);
+	for (i=0; i < log->l_iclog_bufs; i++) {
+		*iclogp = (xlog_in_core_t *)
+			  kmem_zalloc(sizeof(xlog_in_core_t), KM_SLEEP);
+		iclog = *iclogp;
+		iclog->hic_data = (xlog_in_core_2_t *)
+			  kmem_zalloc(iclogsize, KM_SLEEP);
+
+		iclog->ic_prev = prev_iclog;
+		prev_iclog = iclog;
+		log->l_iclog_bak[i] = (xfs_caddr_t)&(iclog->ic_header);
+
+		head = &iclog->ic_header;
+		memset(head, 0, sizeof(xlog_rec_header_t));
+		INT_SET(head->h_magicno, ARCH_CONVERT, XLOG_HEADER_MAGIC_NUM);
+		INT_SET(head->h_version, ARCH_CONVERT,
+			XFS_SB_VERSION_HASLOGV2(&log->l_mp->m_sb) ? 2 : 1);
+		INT_SET(head->h_size, ARCH_CONVERT, log->l_iclog_size);
+		/* new fields */
+		INT_SET(head->h_fmt, ARCH_CONVERT, XLOG_FMT);
+		memcpy(&head->h_fs_uuid, &mp->m_sb.sb_uuid, sizeof(uuid_t));
+
+		bp = xfs_buf_get_empty(log->l_iclog_size, mp->m_logdev_targp);
+		XFS_BUF_SET_IODONE_FUNC(bp, xlog_iodone);
+		XFS_BUF_SET_BDSTRAT_FUNC(bp, xlog_bdstrat_cb);
+		XFS_BUF_SET_FSPRIVATE2(bp, (unsigned long)1);
+		iclog->ic_bp = bp;
+
+		iclog->ic_size = XFS_BUF_SIZE(bp) - log->l_iclog_hsize;
+		iclog->ic_state = XLOG_STATE_ACTIVE;
+		iclog->ic_log = log;
+		iclog->ic_callback_tail = &(iclog->ic_callback);
+		iclog->ic_datap = (char *)iclog->hic_data + log->l_iclog_hsize;
+
+		ASSERT(XFS_BUF_ISBUSY(iclog->ic_bp));
+		ASSERT(XFS_BUF_VALUSEMA(iclog->ic_bp) <= 0);
+		sv_init(&iclog->ic_forcesema, SV_DEFAULT, "iclog-force");
+		sv_init(&iclog->ic_writesema, SV_DEFAULT, "iclog-write");
+
+		iclogp = &iclog->ic_next;
+	}
+	*iclogp = log->l_iclog;			/* complete ring */
+	log->l_iclog->ic_prev = prev_iclog;	/* re-write 1st prev ptr */
+
+	return log;
+}	/* xlog_alloc_log */
+
+
+/*
+ * Write out the commit record of a transaction associated with the given
+ * ticket.  Return the lsn of the commit record.
+ */
+STATIC int
+xlog_commit_record(xfs_mount_t  *mp,
+		   xlog_ticket_t *ticket,
+		   xlog_in_core_t **iclog,
+		   xfs_lsn_t	*commitlsnp)
+{
+	int		error;
+	xfs_log_iovec_t	reg[1];
+
+	reg[0].i_addr = NULL;
+	reg[0].i_len = 0;
+
+	ASSERT_ALWAYS(iclog);
+	if ((error = xlog_write(mp, reg, 1, ticket, commitlsnp,
+			       iclog, XLOG_COMMIT_TRANS))) {
+		xfs_force_shutdown(mp, XFS_LOG_IO_ERROR);
+	}
+	return (error);
+}	/* xlog_commit_record */
+
+
+/*
+ * Push on the buffer cache code if we ever use more than 75% of the on-disk
+ * log space.  This code pushes on the lsn which would supposedly free up
+ * the 25% which we want to leave free.  We may need to adopt a policy which
+ * pushes on an lsn which is further along in the log once we reach the high
+ * water mark.  In this manner, we would be creating a low water mark.
+ */
+void
+xlog_grant_push_ail(xfs_mount_t	*mp,
+		    int		need_bytes)
+{
+    xlog_t	*log = mp->m_log;	/* pointer to the log */
+    xfs_lsn_t	tail_lsn;		/* lsn of the log tail */
+    xfs_lsn_t	threshold_lsn = 0;	/* lsn we'd like to be at */
+    int		free_blocks;		/* free blocks left to write to */
+    int		free_bytes;		/* free bytes left to write to */
+    int		threshold_block;	/* block in lsn we'd like to be at */
+    int		threshold_cycle;	/* lsn cycle we'd like to be at */
+    int		free_threshold;
+    SPLDECL(s);
+
+    ASSERT(BTOBB(need_bytes) < log->l_logBBsize);
+
+    s = GRANT_LOCK(log);
+    free_bytes = xlog_space_left(log,
+				 log->l_grant_reserve_cycle,
+				 log->l_grant_reserve_bytes);
+    tail_lsn = log->l_tail_lsn;
+    free_blocks = BTOBBT(free_bytes);
+
+    /*
+     * Set the threshold for the minimum number of free blocks in the
+     * log to the maximum of what the caller needs, one quarter of the
+     * log, and 256 blocks.
+     */
+    free_threshold = BTOBB(need_bytes);
+    free_threshold = MAX(free_threshold, (log->l_logBBsize >> 2));
+    free_threshold = MAX(free_threshold, 256);
+    if (free_blocks < free_threshold) {
+	threshold_block = BLOCK_LSN(tail_lsn) + free_threshold;
+	threshold_cycle = CYCLE_LSN(tail_lsn);
+	if (threshold_block >= log->l_logBBsize) {
+	    threshold_block -= log->l_logBBsize;
+	    threshold_cycle += 1;
+	}
+	ASSIGN_ANY_LSN_HOST(threshold_lsn, threshold_cycle,
+		       threshold_block);
+
+	/* Don't pass in an lsn greater than the lsn of the last
+	 * log record known to be on disk.
+	 */
+	if (XFS_LSN_CMP(threshold_lsn, log->l_last_sync_lsn) > 0)
+	    threshold_lsn = log->l_last_sync_lsn;
+    }
+    GRANT_UNLOCK(log, s);
+
+    /*
+     * Get the transaction layer to kick the dirty buffers out to
+     * disk asynchronously. No point in trying to do this if
+     * the filesystem is shutting down.
+     */
+    if (threshold_lsn &&
+	!XLOG_FORCED_SHUTDOWN(log))
+	    xfs_trans_push_ail(mp, threshold_lsn);
+}	/* xlog_grant_push_ail */
+
+
+/*
+ * Flush out the in-core log (iclog) to the on-disk log in an asynchronous 
+ * fashion.  Previously, we should have moved the current iclog
+ * ptr in the log to point to the next available iclog.  This allows further
+ * write to continue while this code syncs out an iclog ready to go.
+ * Before an in-core log can be written out, the data section must be scanned
+ * to save away the 1st word of each BBSIZE block into the header.  We replace
+ * it with the current cycle count.  Each BBSIZE block is tagged with the
+ * cycle count because there in an implicit assumption that drives will
+ * guarantee that entire 512 byte blocks get written at once.  In other words,
+ * we can't have part of a 512 byte block written and part not written.  By
+ * tagging each block, we will know which blocks are valid when recovering
+ * after an unclean shutdown.
+ *
+ * This routine is single threaded on the iclog.  No other thread can be in
+ * this routine with the same iclog.  Changing contents of iclog can there-
+ * fore be done without grabbing the state machine lock.  Updating the global
+ * log will require grabbing the lock though.
+ *
+ * The entire log manager uses a logical block numbering scheme.  Only
+ * log_sync (and then only bwrite()) know about the fact that the log may
+ * not start with block zero on a given device.  The log block start offset
+ * is added immediately before calling bwrite().
+ */
+
+int
+xlog_sync(xlog_t		*log,
+	  xlog_in_core_t	*iclog)
+{
+	xfs_caddr_t	dptr;		/* pointer to byte sized element */
+	xfs_buf_t	*bp;
+	int		i, ops;
+	uint		count;		/* byte count of bwrite */
+	uint		count_init;	/* initial count before roundup */
+	int		roundoff;       /* roundoff to BB or stripe */
+	int		split = 0;	/* split write into two regions */
+	int		error;
+	SPLDECL(s);
+	int		v2 = XFS_SB_VERSION_HASLOGV2(&log->l_mp->m_sb);
+
+	XFS_STATS_INC(xs_log_writes);
+	ASSERT(iclog->ic_refcnt == 0);
+
+	/* Add for LR header */
+	count_init = log->l_iclog_hsize + iclog->ic_offset;
+
+	/* Round out the log write size */
+	if (v2 && log->l_mp->m_sb.sb_logsunit > 1) {
+		/* we have a v2 stripe unit to use */
+		count = XLOG_LSUNITTOB(log, XLOG_BTOLSUNIT(log, count_init));
+	} else {
+		count = BBTOB(BTOBB(count_init));
+	}
+	roundoff = count - count_init;
+	ASSERT(roundoff >= 0);
+	ASSERT((v2 && log->l_mp->m_sb.sb_logsunit > 1 && 
+                roundoff < log->l_mp->m_sb.sb_logsunit)
+		|| 
+		(log->l_mp->m_sb.sb_logsunit <= 1 && 
+		 roundoff < BBTOB(1)));
+
+	/* move grant heads by roundoff in sync */
+	s = GRANT_LOCK(log);
+	XLOG_GRANT_ADD_SPACE(log, roundoff, 'w');
+	XLOG_GRANT_ADD_SPACE(log, roundoff, 'r');
+	GRANT_UNLOCK(log, s);
+
+	/* put cycle number in every block */
+	xlog_pack_data(log, iclog, roundoff); 
+
+	/* real byte length */
+	if (v2) {
+		INT_SET(iclog->ic_header.h_len, 
+			ARCH_CONVERT,
+			iclog->ic_offset + roundoff);
+	} else {
+		INT_SET(iclog->ic_header.h_len, ARCH_CONVERT, iclog->ic_offset);
+	}
+
+	/* put ops count in correct order */
+	ops = iclog->ic_header.h_num_logops;
+	INT_SET(iclog->ic_header.h_num_logops, ARCH_CONVERT, ops);
+
+	bp	    = iclog->ic_bp;
+	ASSERT(XFS_BUF_FSPRIVATE2(bp, unsigned long) == (unsigned long)1);
+	XFS_BUF_SET_FSPRIVATE2(bp, (unsigned long)2);
+	XFS_BUF_SET_ADDR(bp, BLOCK_LSN(INT_GET(iclog->ic_header.h_lsn, ARCH_CONVERT)));
+
+	XFS_STATS_ADD(xs_log_blocks, BTOBB(count));
+
+	/* Do we need to split this write into 2 parts? */
+	if (XFS_BUF_ADDR(bp) + BTOBB(count) > log->l_logBBsize) {
+		split = count - (BBTOB(log->l_logBBsize - XFS_BUF_ADDR(bp)));
+		count = BBTOB(log->l_logBBsize - XFS_BUF_ADDR(bp));
+		iclog->ic_bwritecnt = 2;	/* split into 2 writes */
+	} else {
+		iclog->ic_bwritecnt = 1;
+	}
+	XFS_BUF_SET_PTR(bp, (xfs_caddr_t) &(iclog->ic_header), count);
+	XFS_BUF_SET_FSPRIVATE(bp, iclog);	/* save for later */
+	XFS_BUF_BUSY(bp);
+	XFS_BUF_ASYNC(bp);
+	/*
+	 * Do a disk write cache flush for the log block.
+	 * This is a bit of a sledgehammer, it would be better
+	 * to use a tag barrier here that just prevents reordering.
+	 * It may not be needed to flush the first split block in the log wrap
+	 * case, but do it anyways to be safe -AK
+	 */
+	if (!(log->l_mp->m_flags & XFS_MOUNT_NOLOGFLUSH))
+		XFS_BUF_FLUSH(bp);
+
+	ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1);
+	ASSERT(XFS_BUF_ADDR(bp) + BTOBB(count) <= log->l_logBBsize);
+
+	xlog_verify_iclog(log, iclog, count, B_TRUE);
+
+	/* account for log which doesn't start at block #0 */
+	XFS_BUF_SET_ADDR(bp, XFS_BUF_ADDR(bp) + log->l_logBBstart);
+	/*
+	 * Don't call xfs_bwrite here. We do log-syncs even when the filesystem
+	 * is shutting down.
+	 */
+	XFS_BUF_WRITE(bp);
+
+	if ((error = XFS_bwrite(bp))) {
+		xfs_ioerror_alert("xlog_sync", log->l_mp, bp,
+				  XFS_BUF_ADDR(bp));
+		return (error);
+	}
+	if (split) {
+		bp		= iclog->ic_log->l_xbuf;
+		ASSERT(XFS_BUF_FSPRIVATE2(bp, unsigned long) ==
+							(unsigned long)1);
+		XFS_BUF_SET_FSPRIVATE2(bp, (unsigned long)2);
+		XFS_BUF_SET_ADDR(bp, 0);	     /* logical 0 */
+		XFS_BUF_SET_PTR(bp, (xfs_caddr_t)((__psint_t)&(iclog->ic_header)+
+					    (__psint_t)count), split);
+		XFS_BUF_SET_FSPRIVATE(bp, iclog);
+		XFS_BUF_BUSY(bp);
+		XFS_BUF_ASYNC(bp);
+		if (!(log->l_mp->m_flags & XFS_MOUNT_NOLOGFLUSH))
+			XFS_BUF_FLUSH(bp);
+		dptr = XFS_BUF_PTR(bp);
+		/*
+		 * Bump the cycle numbers at the start of each block
+		 * since this part of the buffer is at the start of
+		 * a new cycle.  Watch out for the header magic number
+		 * case, though.
+		 */
+		for (i=0; i<split; i += BBSIZE) {
+			INT_MOD(*(uint *)dptr, ARCH_CONVERT, +1);
+			if (INT_GET(*(uint *)dptr, ARCH_CONVERT) == XLOG_HEADER_MAGIC_NUM)
+				INT_MOD(*(uint *)dptr, ARCH_CONVERT, +1);
+			dptr += BBSIZE;
+		}
+
+		ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1);
+		ASSERT(XFS_BUF_ADDR(bp) + BTOBB(count) <= log->l_logBBsize);
+
+		/* account for internal log which does't start at block #0 */
+		XFS_BUF_SET_ADDR(bp, XFS_BUF_ADDR(bp) + log->l_logBBstart);
+		XFS_BUF_WRITE(bp);
+		if ((error = XFS_bwrite(bp))) {
+			xfs_ioerror_alert("xlog_sync (split)", log->l_mp,
+					  bp, XFS_BUF_ADDR(bp));
+			return (error);
+		}
+	}
+	return (0);
+}	/* xlog_sync */
+
+
+/*
+ * Unallocate a log structure
+ */
+void
+xlog_unalloc_log(xlog_t *log)
+{
+	xlog_in_core_t	*iclog, *next_iclog;
+	xlog_ticket_t	*tic, *next_tic;
+	int		i;
+
+
+	iclog = log->l_iclog;
+	for (i=0; i<log->l_iclog_bufs; i++) {
+		sv_destroy(&iclog->ic_forcesema);
+		sv_destroy(&iclog->ic_writesema);
+		xfs_buf_free(iclog->ic_bp);
+#ifdef XFS_LOG_TRACE
+		if (iclog->ic_trace != NULL) {
+			ktrace_free(iclog->ic_trace);
+		}
+#endif
+		next_iclog = iclog->ic_next;
+		kmem_free(iclog->hic_data, log->l_iclog_size);
+		kmem_free(iclog, sizeof(xlog_in_core_t));
+		iclog = next_iclog;
+	}
+	freesema(&log->l_flushsema);
+	spinlock_destroy(&log->l_icloglock);
+	spinlock_destroy(&log->l_grant_lock);
+
+	/* XXXsup take a look at this again. */
+	if ((log->l_ticket_cnt != log->l_ticket_tcnt)  &&
+	    !XLOG_FORCED_SHUTDOWN(log)) {
+		xfs_fs_cmn_err(CE_WARN, log->l_mp,
+			"xlog_unalloc_log: (cnt: %d, total: %d)",
+			log->l_ticket_cnt, log->l_ticket_tcnt);
+		/* ASSERT(log->l_ticket_cnt == log->l_ticket_tcnt); */
+
+	} else {
+		tic = log->l_unmount_free;
+		while (tic) {
+			next_tic = tic->t_next;
+			kmem_free(tic, NBPP);
+			tic = next_tic;
+		}
+	}
+	xfs_buf_free(log->l_xbuf);
+#ifdef XFS_LOG_TRACE
+	if (log->l_trace != NULL) {
+		ktrace_free(log->l_trace);
+	}
+	if (log->l_grant_trace != NULL) {
+		ktrace_free(log->l_grant_trace);
+	}
+#endif
+	log->l_mp->m_log = NULL;
+	kmem_free(log, sizeof(xlog_t));
+}	/* xlog_unalloc_log */
+
+/*
+ * Update counters atomically now that memcpy is done.
+ */
+/* ARGSUSED */
+static inline void
+xlog_state_finish_copy(xlog_t		*log,
+		       xlog_in_core_t	*iclog,
+		       int		record_cnt,
+		       int		copy_bytes)
+{
+	SPLDECL(s);
+
+	s = LOG_LOCK(log);
+
+	iclog->ic_header.h_num_logops += record_cnt;
+	iclog->ic_offset += copy_bytes;
+
+	LOG_UNLOCK(log, s);
+}	/* xlog_state_finish_copy */
+
+
+
+
+/*
+ * Write some region out to in-core log
+ *
+ * This will be called when writing externally provided regions or when
+ * writing out a commit record for a given transaction.
+ *
+ * General algorithm:
+ *	1. Find total length of this write.  This may include adding to the
+ *		lengths passed in.
+ *	2. Check whether we violate the tickets reservation.
+ *	3. While writing to this iclog
+ *	    A. Reserve as much space in this iclog as can get
+ *	    B. If this is first write, save away start lsn
+ *	    C. While writing this region:
+ *		1. If first write of transaction, write start record
+ *		2. Write log operation header (header per region)
+ *		3. Find out if we can fit entire region into this iclog
+ *		4. Potentially, verify destination memcpy ptr
+ *		5. Memcpy (partial) region
+ *		6. If partial copy, release iclog; otherwise, continue
+ *			copying more regions into current iclog
+ *	4. Mark want sync bit (in simulation mode)
+ *	5. Release iclog for potential flush to on-disk log.
+ *
+ * ERRORS:
+ * 1.	Panic if reservation is overrun.  This should never happen since
+ *	reservation amounts are generated internal to the filesystem.
+ * NOTES:
+ * 1. Tickets are single threaded data structures.
+ * 2. The XLOG_END_TRANS & XLOG_CONTINUE_TRANS flags are passed down to the
+ *	syncing routine.  When a single log_write region needs to span
+ *	multiple in-core logs, the XLOG_CONTINUE_TRANS bit should be set
+ *	on all log operation writes which don't contain the end of the
+ *	region.  The XLOG_END_TRANS bit is used for the in-core log
+ *	operation which contains the end of the continued log_write region.
+ * 3. When xlog_state_get_iclog_space() grabs the rest of the current iclog,
+ *	we don't really know exactly how much space will be used.  As a result,
+ *	we don't update ic_offset until the end when we know exactly how many
+ *	bytes have been written out.
+ */
+int
+xlog_write(xfs_mount_t *	mp,
+	   xfs_log_iovec_t	reg[],
+	   int			nentries,
+	   xfs_log_ticket_t	tic,
+	   xfs_lsn_t		*start_lsn,
+	   xlog_in_core_t	**commit_iclog,
+	   uint			flags)
+{
+    xlog_t	     *log    = mp->m_log;
+    xlog_ticket_t    *ticket = (xlog_ticket_t *)tic;
+    xlog_op_header_t *logop_head;    /* ptr to log operation header */
+    xlog_in_core_t   *iclog;	     /* ptr to current in-core log */
+    __psint_t	     ptr;	     /* copy address into data region */
+    int		     len;	     /* # xlog_write() bytes 2 still copy */
+    int		     index;	     /* region index currently copying */
+    int		     log_offset;     /* offset (from 0) into data region */
+    int		     start_rec_copy; /* # bytes to copy for start record */
+    int		     partial_copy;   /* did we split a region? */
+    int		     partial_copy_len;/* # bytes copied if split region */
+    int		     need_copy;	     /* # bytes need to memcpy this region */
+    int		     copy_len;	     /* # bytes actually memcpy'ing */
+    int		     copy_off;	     /* # bytes from entry start */
+    int		     contwr;	     /* continued write of in-core log? */
+    int		     error;
+    int		     record_cnt = 0, data_cnt = 0;
+
+    partial_copy_len = partial_copy = 0;
+
+    /* Calculate potential maximum space.  Each region gets its own
+     * xlog_op_header_t and may need to be double word aligned.
+     */
+    len = 0;
+    if (ticket->t_flags & XLOG_TIC_INITED)     /* acct for start rec of xact */
+	len += sizeof(xlog_op_header_t);
+
+    for (index = 0; index < nentries; index++) {
+	len += sizeof(xlog_op_header_t);	    /* each region gets >= 1 */
+	len += reg[index].i_len;
+    }
+    contwr = *start_lsn = 0;
+
+    if (ticket->t_curr_res < len) {
+#ifdef DEBUG
+	xlog_panic(
+		"xfs_log_write: reservation ran out. Need to up reservation");
+#else
+	/* Customer configurable panic */
+	xfs_cmn_err(XFS_PTAG_LOGRES, CE_ALERT, mp,
+		"xfs_log_write: reservation ran out. Need to up reservation");
+	/* If we did not panic, shutdown the filesystem */
+	xfs_force_shutdown(mp, XFS_CORRUPT_INCORE);
+#endif
+    } else
+	ticket->t_curr_res -= len;
+
+    for (index = 0; index < nentries; ) {
+	if ((error = xlog_state_get_iclog_space(log, len, &iclog, ticket,
+					       &contwr, &log_offset)))
+		return (error);
+
+	ASSERT(log_offset <= iclog->ic_size - 1);
+	ptr = (__psint_t) ((char *)iclog->ic_datap+log_offset);
+
+	/* start_lsn is the first lsn written to. That's all we need. */
+	if (! *start_lsn)
+	    *start_lsn = INT_GET(iclog->ic_header.h_lsn, ARCH_CONVERT);
+
+	/* This loop writes out as many regions as can fit in the amount
+	 * of space which was allocated by xlog_state_get_iclog_space().
+	 */
+	while (index < nentries) {
+	    ASSERT(reg[index].i_len % sizeof(__int32_t) == 0);
+	    ASSERT((__psint_t)ptr % sizeof(__int32_t) == 0);
+	    start_rec_copy = 0;
+
+	    /* If first write for transaction, insert start record.
+	     * We can't be trying to commit if we are inited.  We can't
+	     * have any "partial_copy" if we are inited.
+	     */
+	    if (ticket->t_flags & XLOG_TIC_INITED) {
+		logop_head		= (xlog_op_header_t *)ptr;
+		INT_SET(logop_head->oh_tid, ARCH_CONVERT, ticket->t_tid);
+		logop_head->oh_clientid = ticket->t_clientid;
+		logop_head->oh_len	= 0;
+		logop_head->oh_flags    = XLOG_START_TRANS;
+		logop_head->oh_res2	= 0;
+		ticket->t_flags		&= ~XLOG_TIC_INITED;	/* clear bit */
+		record_cnt++;
+
+		start_rec_copy = sizeof(xlog_op_header_t);
+		xlog_write_adv_cnt(ptr, len, log_offset, start_rec_copy);
+	    }
+
+	    /* Copy log operation header directly into data section */
+	    logop_head			= (xlog_op_header_t *)ptr;
+	    INT_SET(logop_head->oh_tid, ARCH_CONVERT, ticket->t_tid);
+	    logop_head->oh_clientid	= ticket->t_clientid;
+	    logop_head->oh_res2		= 0;
+
+	    /* header copied directly */
+	    xlog_write_adv_cnt(ptr, len, log_offset, sizeof(xlog_op_header_t));
+
+	    /* are we copying a commit or unmount record? */
+	    logop_head->oh_flags = flags;
+
+	    /*
+	     * We've seen logs corrupted with bad transaction client
+	     * ids.  This makes sure that XFS doesn't generate them on.
+	     * Turn this into an EIO and shut down the filesystem.
+	     */
+	    switch (logop_head->oh_clientid)  {
+	    case XFS_TRANSACTION:
+	    case XFS_VOLUME:
+	    case XFS_LOG:
+		break;
+	    default:
+		xfs_fs_cmn_err(CE_WARN, mp,
+		    "Bad XFS transaction clientid 0x%x in ticket 0x%p",
+		    logop_head->oh_clientid, tic);
+		return XFS_ERROR(EIO);
+	    }
+
+	    /* Partial write last time? => (partial_copy != 0)
+	     * need_copy is the amount we'd like to copy if everything could
+	     * fit in the current memcpy.
+	     */
+	    need_copy =	reg[index].i_len - partial_copy_len;
+
+	    copy_off = partial_copy_len;
+	    if (need_copy <= iclog->ic_size - log_offset) { /*complete write */
+		INT_SET(logop_head->oh_len, ARCH_CONVERT, copy_len = need_copy);
+		if (partial_copy)
+		    logop_head->oh_flags|= (XLOG_END_TRANS|XLOG_WAS_CONT_TRANS);
+		partial_copy_len = partial_copy = 0;
+	    } else {					    /* partial write */
+		copy_len = iclog->ic_size - log_offset;
+		INT_SET(logop_head->oh_len, ARCH_CONVERT, copy_len);
+		logop_head->oh_flags |= XLOG_CONTINUE_TRANS;
+		if (partial_copy)
+			logop_head->oh_flags |= XLOG_WAS_CONT_TRANS;
+		partial_copy_len += copy_len;
+		partial_copy++;
+		len += sizeof(xlog_op_header_t); /* from splitting of region */
+		/* account for new log op header */
+		ticket->t_curr_res -= sizeof(xlog_op_header_t);
+	    }
+	    xlog_verify_dest_ptr(log, ptr);
+
+	    /* copy region */
+	    ASSERT(copy_len >= 0);
+	    memcpy((xfs_caddr_t)ptr, reg[index].i_addr + copy_off, copy_len);
+	    xlog_write_adv_cnt(ptr, len, log_offset, copy_len);
+
+	    /* make copy_len total bytes copied, including headers */
+	    copy_len += start_rec_copy + sizeof(xlog_op_header_t);
+	    record_cnt++;
+	    data_cnt += contwr ? copy_len : 0;
+	    if (partial_copy) {			/* copied partial region */
+		    /* already marked WANT_SYNC by xlog_state_get_iclog_space */
+		    xlog_state_finish_copy(log, iclog, record_cnt, data_cnt);
+		    record_cnt = data_cnt = 0;
+		    if ((error = xlog_state_release_iclog(log, iclog)))
+			    return (error);
+		    break;			/* don't increment index */
+	    } else {				/* copied entire region */
+		index++;
+		partial_copy_len = partial_copy = 0;
+
+		if (iclog->ic_size - log_offset <= sizeof(xlog_op_header_t)) {
+		    xlog_state_finish_copy(log, iclog, record_cnt, data_cnt);
+		    record_cnt = data_cnt = 0;
+		    xlog_state_want_sync(log, iclog);
+		    if (commit_iclog) {
+			ASSERT(flags & XLOG_COMMIT_TRANS);
+			*commit_iclog = iclog;
+		    } else if ((error = xlog_state_release_iclog(log, iclog)))
+			   return (error);
+		    if (index == nentries)
+			    return 0;		/* we are done */
+		    else
+			    break;
+		}
+	    } /* if (partial_copy) */
+	} /* while (index < nentries) */
+    } /* for (index = 0; index < nentries; ) */
+    ASSERT(len == 0);
+
+    xlog_state_finish_copy(log, iclog, record_cnt, data_cnt);
+    if (commit_iclog) {
+	ASSERT(flags & XLOG_COMMIT_TRANS);
+	*commit_iclog = iclog;
+	return 0;
+    }
+    return (xlog_state_release_iclog(log, iclog));
+}	/* xlog_write */
+
+
+/*****************************************************************************
+ *
+ *		State Machine functions
+ *
+ *****************************************************************************
+ */
+
+/* Clean iclogs starting from the head.  This ordering must be
+ * maintained, so an iclog doesn't become ACTIVE beyond one that
+ * is SYNCING.  This is also required to maintain the notion that we use
+ * a counting semaphore to hold off would be writers to the log when every
+ * iclog is trying to sync to disk.
+ *
+ * State Change: DIRTY -> ACTIVE
+ */
+void
+xlog_state_clean_log(xlog_t *log)
+{
+	xlog_in_core_t	*iclog;
+	int changed = 0;
+
+	iclog = log->l_iclog;
+	do {
+		if (iclog->ic_state == XLOG_STATE_DIRTY) {
+			iclog->ic_state	= XLOG_STATE_ACTIVE;
+			iclog->ic_offset       = 0;
+			iclog->ic_callback	= NULL;   /* don't need to free */
+			/*
+			 * If the number of ops in this iclog indicate it just
+			 * contains the dummy transaction, we can
+			 * change state into IDLE (the second time around).
+			 * Otherwise we should change the state into
+			 * NEED a dummy.
+			 * We don't need to cover the dummy.
+			 */
+			if (!changed &&
+			   (INT_GET(iclog->ic_header.h_num_logops, ARCH_CONVERT) == XLOG_COVER_OPS)) {
+				changed = 1;
+			} else {
+				/*
+				 * We have two dirty iclogs so start over
+				 * This could also be num of ops indicates
+				 * this is not the dummy going out.
+				 */
+				changed = 2;
+			}
+			iclog->ic_header.h_num_logops = 0;
+			memset(iclog->ic_header.h_cycle_data, 0,
+			      sizeof(iclog->ic_header.h_cycle_data));
+			iclog->ic_header.h_lsn = 0;
+		} else if (iclog->ic_state == XLOG_STATE_ACTIVE)
+			/* do nothing */;
+		else
+			break;	/* stop cleaning */
+		iclog = iclog->ic_next;
+	} while (iclog != log->l_iclog);
+
+	/* log is locked when we are called */
+	/*
+	 * Change state for the dummy log recording.
+	 * We usually go to NEED. But we go to NEED2 if the changed indicates
+	 * we are done writing the dummy record.
+	 * If we are done with the second dummy recored (DONE2), then
+	 * we go to IDLE.
+	 */
+	if (changed) {
+		switch (log->l_covered_state) {
+		case XLOG_STATE_COVER_IDLE:
+		case XLOG_STATE_COVER_NEED:
+		case XLOG_STATE_COVER_NEED2:
+			log->l_covered_state = XLOG_STATE_COVER_NEED;
+			break;
+
+		case XLOG_STATE_COVER_DONE:
+			if (changed == 1)
+				log->l_covered_state = XLOG_STATE_COVER_NEED2;
+			else
+				log->l_covered_state = XLOG_STATE_COVER_NEED;
+			break;
+
+		case XLOG_STATE_COVER_DONE2:
+			if (changed == 1)
+				log->l_covered_state = XLOG_STATE_COVER_IDLE;
+			else
+				log->l_covered_state = XLOG_STATE_COVER_NEED;
+			break;
+
+		default:
+			ASSERT(0);
+		}
+	}
+}	/* xlog_state_clean_log */
+
+STATIC xfs_lsn_t
+xlog_get_lowest_lsn(
+	xlog_t		*log)
+{
+	xlog_in_core_t  *lsn_log;
+	xfs_lsn_t	lowest_lsn, lsn;
+
+	lsn_log = log->l_iclog;
+	lowest_lsn = 0;
+	do {
+	    if (!(lsn_log->ic_state & (XLOG_STATE_ACTIVE|XLOG_STATE_DIRTY))) {
+		lsn = INT_GET(lsn_log->ic_header.h_lsn, ARCH_CONVERT);
+		if ((lsn && !lowest_lsn) ||
+		    (XFS_LSN_CMP(lsn, lowest_lsn) < 0)) {
+			lowest_lsn = lsn;
+		}
+	    }
+	    lsn_log = lsn_log->ic_next;
+	} while (lsn_log != log->l_iclog);
+	return(lowest_lsn);
+}
+
+
+STATIC void
+xlog_state_do_callback(
+	xlog_t		*log,
+	int		aborted,
+	xlog_in_core_t	*ciclog)
+{
+	xlog_in_core_t	   *iclog;
+	xlog_in_core_t	   *first_iclog;	/* used to know when we've
+						 * processed all iclogs once */
+	xfs_log_callback_t *cb, *cb_next;
+	int		   flushcnt = 0;
+	xfs_lsn_t	   lowest_lsn;
+	int		   ioerrors;	/* counter: iclogs with errors */
+	int		   loopdidcallbacks; /* flag: inner loop did callbacks*/
+	int		   funcdidcallbacks; /* flag: function did callbacks */
+	int		   repeats;	/* for issuing console warnings if
+					 * looping too many times */
+	SPLDECL(s);
+
+	s = LOG_LOCK(log);
+	first_iclog = iclog = log->l_iclog;
+	ioerrors = 0;
+	funcdidcallbacks = 0;
+	repeats = 0;
+
+	do {
+		/*
+		 * Scan all iclogs starting with the one pointed to by the
+		 * log.  Reset this starting point each time the log is
+		 * unlocked (during callbacks).
+		 *
+		 * Keep looping through iclogs until one full pass is made
+		 * without running any callbacks.
+		 */
+		first_iclog = log->l_iclog;
+		iclog = log->l_iclog;
+		loopdidcallbacks = 0;
+		repeats++;
+
+		do {
+
+			/* skip all iclogs in the ACTIVE & DIRTY states */
+			if (iclog->ic_state &
+			    (XLOG_STATE_ACTIVE|XLOG_STATE_DIRTY)) {
+				iclog = iclog->ic_next;
+				continue;
+			}
+
+			/*
+			 * Between marking a filesystem SHUTDOWN and stopping
+			 * the log, we do flush all iclogs to disk (if there
+			 * wasn't a log I/O error). So, we do want things to
+			 * go smoothly in case of just a SHUTDOWN  w/o a
+			 * LOG_IO_ERROR.
+			 */
+			if (!(iclog->ic_state & XLOG_STATE_IOERROR)) {
+				/*
+				 * Can only perform callbacks in order.  Since
+				 * this iclog is not in the DONE_SYNC/
+				 * DO_CALLBACK state, we skip the rest and
+				 * just try to clean up.  If we set our iclog
+				 * to DO_CALLBACK, we will not process it when
+				 * we retry since a previous iclog is in the
+				 * CALLBACK and the state cannot change since
+				 * we are holding the LOG_LOCK.
+				 */
+				if (!(iclog->ic_state &
+					(XLOG_STATE_DONE_SYNC |
+						 XLOG_STATE_DO_CALLBACK))) {
+					if (ciclog && (ciclog->ic_state ==
+							XLOG_STATE_DONE_SYNC)) {
+						ciclog->ic_state = XLOG_STATE_DO_CALLBACK;
+					}
+					break;
+				}
+				/*
+				 * We now have an iclog that is in either the
+				 * DO_CALLBACK or DONE_SYNC states. The other
+				 * states (WANT_SYNC, SYNCING, or CALLBACK were
+				 * caught by the above if and are going to
+				 * clean (i.e. we aren't doing their callbacks)
+				 * see the above if.
+				 */
+
+				/*
+				 * We will do one more check here to see if we
+				 * have chased our tail around.
+				 */
+
+				lowest_lsn = xlog_get_lowest_lsn(log);
+				if (lowest_lsn && (
+					XFS_LSN_CMP(
+						lowest_lsn,
+						INT_GET(iclog->ic_header.h_lsn, ARCH_CONVERT)
+					)<0)) {
+					iclog = iclog->ic_next;
+					continue; /* Leave this iclog for
+						   * another thread */
+				}
+
+				iclog->ic_state = XLOG_STATE_CALLBACK;
+
+				LOG_UNLOCK(log, s);
+
+				/* l_last_sync_lsn field protected by
+				 * GRANT_LOCK. Don't worry about iclog's lsn.
+				 * No one else can be here except us.
+				 */
+				s = GRANT_LOCK(log);
+				ASSERT(XFS_LSN_CMP(
+						log->l_last_sync_lsn,
+						INT_GET(iclog->ic_header.h_lsn, ARCH_CONVERT)
+					)<=0);
+				log->l_last_sync_lsn = INT_GET(iclog->ic_header.h_lsn, ARCH_CONVERT);
+				GRANT_UNLOCK(log, s);
+
+				/*
+				 * Keep processing entries in the callback list
+				 * until we come around and it is empty.  We
+				 * need to atomically see that the list is
+				 * empty and change the state to DIRTY so that
+				 * we don't miss any more callbacks being added.
+				 */
+				s = LOG_LOCK(log);
+			} else {
+				ioerrors++;
+			}
+			cb = iclog->ic_callback;
+
+			while (cb != 0) {
+				iclog->ic_callback_tail = &(iclog->ic_callback);
+				iclog->ic_callback = NULL;
+				LOG_UNLOCK(log, s);
+
+				/* perform callbacks in the order given */
+				for (; cb != 0; cb = cb_next) {
+					cb_next = cb->cb_next;
+					cb->cb_func(cb->cb_arg, aborted);
+				}
+				s = LOG_LOCK(log);
+				cb = iclog->ic_callback;
+			}
+
+			loopdidcallbacks++;
+			funcdidcallbacks++;
+
+			ASSERT(iclog->ic_callback == 0);
+			if (!(iclog->ic_state & XLOG_STATE_IOERROR))
+				iclog->ic_state = XLOG_STATE_DIRTY;
+
+			/*
+			 * Transition from DIRTY to ACTIVE if applicable.
+			 * NOP if STATE_IOERROR.
+			 */
+			xlog_state_clean_log(log);
+
+			/* wake up threads waiting in xfs_log_force() */
+			sv_broadcast(&iclog->ic_forcesema);
+
+			iclog = iclog->ic_next;
+		} while (first_iclog != iclog);
+		if (repeats && (repeats % 10) == 0) {
+			xfs_fs_cmn_err(CE_WARN, log->l_mp,
+				"xlog_state_do_callback: looping %d", repeats);
+		}
+	} while (!ioerrors && loopdidcallbacks);
+
+	/*
+	 * make one last gasp attempt to see if iclogs are being left in
+	 * limbo..
+	 */
+#ifdef DEBUG
+	if (funcdidcallbacks) {
+		first_iclog = iclog = log->l_iclog;
+		do {
+			ASSERT(iclog->ic_state != XLOG_STATE_DO_CALLBACK);
+			/*
+			 * Terminate the loop if iclogs are found in states
+			 * which will cause other threads to clean up iclogs.
+			 *
+			 * SYNCING - i/o completion will go through logs
+			 * DONE_SYNC - interrupt thread should be waiting for
+			 *              LOG_LOCK
+			 * IOERROR - give up hope all ye who enter here
+			 */
+			if (iclog->ic_state == XLOG_STATE_WANT_SYNC ||
+			    iclog->ic_state == XLOG_STATE_SYNCING ||
+			    iclog->ic_state == XLOG_STATE_DONE_SYNC ||
+			    iclog->ic_state == XLOG_STATE_IOERROR )
+				break;
+			iclog = iclog->ic_next;
+		} while (first_iclog != iclog);
+	}
+#endif
+
+	if (log->l_iclog->ic_state & (XLOG_STATE_ACTIVE|XLOG_STATE_IOERROR)) {
+		flushcnt = log->l_flushcnt;
+		log->l_flushcnt = 0;
+	}
+	LOG_UNLOCK(log, s);
+	while (flushcnt--)
+		vsema(&log->l_flushsema);
+}	/* xlog_state_do_callback */
+
+
+/*
+ * Finish transitioning this iclog to the dirty state.
+ *
+ * Make sure that we completely execute this routine only when this is
+ * the last call to the iclog.  There is a good chance that iclog flushes,
+ * when we reach the end of the physical log, get turned into 2 separate
+ * calls to bwrite.  Hence, one iclog flush could generate two calls to this
+ * routine.  By using the reference count bwritecnt, we guarantee that only
+ * the second completion goes through.
+ *
+ * Callbacks could take time, so they are done outside the scope of the
+ * global state machine log lock.  Assume that the calls to cvsema won't
+ * take a long time.  At least we know it won't sleep.
+ */
+void
+xlog_state_done_syncing(
+	xlog_in_core_t	*iclog,
+	int		aborted)
+{
+	xlog_t		   *log = iclog->ic_log;
+	SPLDECL(s);
+
+	s = LOG_LOCK(log);
+
+	ASSERT(iclog->ic_state == XLOG_STATE_SYNCING ||
+	       iclog->ic_state == XLOG_STATE_IOERROR);
+	ASSERT(iclog->ic_refcnt == 0);
+	ASSERT(iclog->ic_bwritecnt == 1 || iclog->ic_bwritecnt == 2);
+
+
+	/*
+	 * If we got an error, either on the first buffer, or in the case of
+	 * split log writes, on the second, we mark ALL iclogs STATE_IOERROR,
+	 * and none should ever be attempted to be written to disk
+	 * again.
+	 */
+	if (iclog->ic_state != XLOG_STATE_IOERROR) {
+		if (--iclog->ic_bwritecnt == 1) {
+			LOG_UNLOCK(log, s);
+			return;
+		}
+		iclog->ic_state = XLOG_STATE_DONE_SYNC;
+	}
+
+	/*
+	 * Someone could be sleeping prior to writing out the next
+	 * iclog buffer, we wake them all, one will get to do the
+	 * I/O, the others get to wait for the result.
+	 */
+	sv_broadcast(&iclog->ic_writesema);
+	LOG_UNLOCK(log, s);
+	xlog_state_do_callback(log, aborted, iclog);	/* also cleans log */
+}	/* xlog_state_done_syncing */
+
+
+/*
+ * If the head of the in-core log ring is not (ACTIVE or DIRTY), then we must
+ * sleep.  The flush semaphore is set to the number of in-core buffers and
+ * decremented around disk syncing.  Therefore, if all buffers are syncing,
+ * this semaphore will cause new writes to sleep until a sync completes.
+ * Otherwise, this code just does p() followed by v().  This approximates
+ * a sleep/wakeup except we can't race.
+ *
+ * The in-core logs are used in a circular fashion. They are not used
+ * out-of-order even when an iclog past the head is free.
+ *
+ * return:
+ *	* log_offset where xlog_write() can start writing into the in-core
+ *		log's data space.
+ *	* in-core log pointer to which xlog_write() should write.
+ *	* boolean indicating this is a continued write to an in-core log.
+ *		If this is the last write, then the in-core log's offset field
+ *		needs to be incremented, depending on the amount of data which
+ *		is copied.
+ */
+int
+xlog_state_get_iclog_space(xlog_t	  *log,
+			   int		  len,
+			   xlog_in_core_t **iclogp,
+			   xlog_ticket_t  *ticket,
+			   int		  *continued_write,
+			   int		  *logoffsetp)
+{
+	SPLDECL(s);
+	int		  log_offset;
+	xlog_rec_header_t *head;
+	xlog_in_core_t	  *iclog;
+	int		  error;
+
+restart:
+	s = LOG_LOCK(log);
+	if (XLOG_FORCED_SHUTDOWN(log)) {
+		LOG_UNLOCK(log, s);
+		return XFS_ERROR(EIO);
+	}
+
+	iclog = log->l_iclog;
+	if (! (iclog->ic_state == XLOG_STATE_ACTIVE)) {
+		log->l_flushcnt++;
+		LOG_UNLOCK(log, s);
+		xlog_trace_iclog(iclog, XLOG_TRACE_SLEEP_FLUSH);
+		XFS_STATS_INC(xs_log_noiclogs);
+		/* Ensure that log writes happen */
+		psema(&log->l_flushsema, PINOD);
+		goto restart;
+	}
+	ASSERT(iclog->ic_state == XLOG_STATE_ACTIVE);
+	head = &iclog->ic_header;
+
+	iclog->ic_refcnt++;			/* prevents sync */
+	log_offset = iclog->ic_offset;
+
+	/* On the 1st write to an iclog, figure out lsn.  This works
+	 * if iclogs marked XLOG_STATE_WANT_SYNC always write out what they are
+	 * committing to.  If the offset is set, that's how many blocks
+	 * must be written.
+	 */
+	if (log_offset == 0) {
+		ticket->t_curr_res -= log->l_iclog_hsize;
+		INT_SET(head->h_cycle, ARCH_CONVERT, log->l_curr_cycle);
+		ASSIGN_LSN(head->h_lsn, log);
+		ASSERT(log->l_curr_block >= 0);
+	}
+
+	/* If there is enough room to write everything, then do it.  Otherwise,
+	 * claim the rest of the region and make sure the XLOG_STATE_WANT_SYNC
+	 * bit is on, so this will get flushed out.  Don't update ic_offset
+	 * until you know exactly how many bytes get copied.  Therefore, wait
+	 * until later to update ic_offset.
+	 *
+	 * xlog_write() algorithm assumes that at least 2 xlog_op_header_t's
+	 * can fit into remaining data section.
+	 */
+	if (iclog->ic_size - iclog->ic_offset < 2*sizeof(xlog_op_header_t)) {
+		xlog_state_switch_iclogs(log, iclog, iclog->ic_size);
+
+		/* If I'm the only one writing to this iclog, sync it to disk */
+		if (iclog->ic_refcnt == 1) {
+			LOG_UNLOCK(log, s);
+			if ((error = xlog_state_release_iclog(log, iclog)))
+				return (error);
+		} else {
+			iclog->ic_refcnt--;
+			LOG_UNLOCK(log, s);
+		}
+		goto restart;
+	}
+
+	/* Do we have enough room to write the full amount in the remainder
+	 * of this iclog?  Or must we continue a write on the next iclog and
+	 * mark this iclog as completely taken?  In the case where we switch
+	 * iclogs (to mark it taken), this particular iclog will release/sync
+	 * to disk in xlog_write().
+	 */
+	if (len <= iclog->ic_size - iclog->ic_offset) {
+		*continued_write = 0;
+		iclog->ic_offset += len;
+	} else {
+		*continued_write = 1;
+		xlog_state_switch_iclogs(log, iclog, iclog->ic_size);
+	}
+	*iclogp = iclog;
+
+	ASSERT(iclog->ic_offset <= iclog->ic_size);
+	LOG_UNLOCK(log, s);
+
+	*logoffsetp = log_offset;
+	return 0;
+}	/* xlog_state_get_iclog_space */
+
+/*
+ * Atomically get the log space required for a log ticket.
+ *
+ * Once a ticket gets put onto the reserveq, it will only return after
+ * the needed reservation is satisfied.
+ */
+STATIC int
+xlog_grant_log_space(xlog_t	   *log,
+		     xlog_ticket_t *tic)
+{
+	int		 free_bytes;
+	int		 need_bytes;
+	SPLDECL(s);
+#ifdef DEBUG
+	xfs_lsn_t	 tail_lsn;
+#endif
+
+
+#ifdef DEBUG
+	if (log->l_flags & XLOG_ACTIVE_RECOVERY)
+		panic("grant Recovery problem");
+#endif
+
+	/* Is there space or do we need to sleep? */
+	s = GRANT_LOCK(log);
+	xlog_trace_loggrant(log, tic, "xlog_grant_log_space: enter");
+
+	/* something is already sleeping; insert new transaction at end */
+	if (log->l_reserve_headq) {
+		XLOG_INS_TICKETQ(log->l_reserve_headq, tic);
+		xlog_trace_loggrant(log, tic,
+				    "xlog_grant_log_space: sleep 1");
+		/*
+		 * Gotta check this before going to sleep, while we're
+		 * holding the grant lock.
+		 */
+		if (XLOG_FORCED_SHUTDOWN(log))
+			goto error_return;
+
+		XFS_STATS_INC(xs_sleep_logspace);
+		sv_wait(&tic->t_sema, PINOD|PLTWAIT, &log->l_grant_lock, s);
+		/*
+		 * If we got an error, and the filesystem is shutting down,
+		 * we'll catch it down below. So just continue...
+		 */
+		xlog_trace_loggrant(log, tic,
+				    "xlog_grant_log_space: wake 1");
+		s = GRANT_LOCK(log);
+	}
+	if (tic->t_flags & XFS_LOG_PERM_RESERV)
+		need_bytes = tic->t_unit_res*tic->t_ocnt;
+	else
+		need_bytes = tic->t_unit_res;
+
+redo:
+	if (XLOG_FORCED_SHUTDOWN(log))
+		goto error_return;
+
+	free_bytes = xlog_space_left(log, log->l_grant_reserve_cycle,
+				     log->l_grant_reserve_bytes);
+	if (free_bytes < need_bytes) {
+		if ((tic->t_flags & XLOG_TIC_IN_Q) == 0)
+			XLOG_INS_TICKETQ(log->l_reserve_headq, tic);
+		xlog_trace_loggrant(log, tic,
+				    "xlog_grant_log_space: sleep 2");
+		XFS_STATS_INC(xs_sleep_logspace);
+		sv_wait(&tic->t_sema, PINOD|PLTWAIT, &log->l_grant_lock, s);
+
+		if (XLOG_FORCED_SHUTDOWN(log)) {
+			s = GRANT_LOCK(log);
+			goto error_return;
+		}
+
+		xlog_trace_loggrant(log, tic,
+				    "xlog_grant_log_space: wake 2");
+		xlog_grant_push_ail(log->l_mp, need_bytes);
+		s = GRANT_LOCK(log);
+		goto redo;
+	} else if (tic->t_flags & XLOG_TIC_IN_Q)
+		XLOG_DEL_TICKETQ(log->l_reserve_headq, tic);
+
+	/* we've got enough space */
+	XLOG_GRANT_ADD_SPACE(log, need_bytes, 'w');
+	XLOG_GRANT_ADD_SPACE(log, need_bytes, 'r');
+#ifdef DEBUG
+	tail_lsn = log->l_tail_lsn;
+	/*
+	 * Check to make sure the grant write head didn't just over lap the
+	 * tail.  If the cycles are the same, we can't be overlapping.
+	 * Otherwise, make sure that the cycles differ by exactly one and
+	 * check the byte count.
+	 */
+	if (CYCLE_LSN(tail_lsn) != log->l_grant_write_cycle) {
+		ASSERT(log->l_grant_write_cycle-1 == CYCLE_LSN(tail_lsn));
+		ASSERT(log->l_grant_write_bytes <= BBTOB(BLOCK_LSN(tail_lsn)));
+	}
+#endif
+	xlog_trace_loggrant(log, tic, "xlog_grant_log_space: exit");
+	xlog_verify_grant_head(log, 1);
+	GRANT_UNLOCK(log, s);
+	return 0;
+
+ error_return:
+	if (tic->t_flags & XLOG_TIC_IN_Q)
+		XLOG_DEL_TICKETQ(log->l_reserve_headq, tic);
+	xlog_trace_loggrant(log, tic, "xlog_grant_log_space: err_ret");
+	/*
+	 * If we are failing, make sure the ticket doesn't have any
+	 * current reservations. We don't want to add this back when
+	 * the ticket/transaction gets cancelled.
+	 */
+	tic->t_curr_res = 0;
+	tic->t_cnt = 0; /* ungrant will give back unit_res * t_cnt. */
+	GRANT_UNLOCK(log, s);
+	return XFS_ERROR(EIO);
+}	/* xlog_grant_log_space */
+
+
+/*
+ * Replenish the byte reservation required by moving the grant write head.
+ *
+ *
+ */
+STATIC int
+xlog_regrant_write_log_space(xlog_t	   *log,
+			     xlog_ticket_t *tic)
+{
+	SPLDECL(s);
+	int		free_bytes, need_bytes;
+	xlog_ticket_t	*ntic;
+#ifdef DEBUG
+	xfs_lsn_t	tail_lsn;
+#endif
+
+	tic->t_curr_res = tic->t_unit_res;
+
+	if (tic->t_cnt > 0)
+		return (0);
+
+#ifdef DEBUG
+	if (log->l_flags & XLOG_ACTIVE_RECOVERY)
+		panic("regrant Recovery problem");
+#endif
+
+	s = GRANT_LOCK(log);
+	xlog_trace_loggrant(log, tic, "xlog_regrant_write_log_space: enter");
+
+	if (XLOG_FORCED_SHUTDOWN(log))
+		goto error_return;
+
+	/* If there are other waiters on the queue then give them a
+	 * chance at logspace before us. Wake up the first waiters,
+	 * if we do not wake up all the waiters then go to sleep waiting
+	 * for more free space, otherwise try to get some space for
+	 * this transaction.
+	 */
+
+	if ((ntic = log->l_write_headq)) {
+		free_bytes = xlog_space_left(log, log->l_grant_write_cycle,
+					     log->l_grant_write_bytes);
+		do {
+			ASSERT(ntic->t_flags & XLOG_TIC_PERM_RESERV);
+
+			if (free_bytes < ntic->t_unit_res)
+				break;
+			free_bytes -= ntic->t_unit_res;
+			sv_signal(&ntic->t_sema);
+			ntic = ntic->t_next;
+		} while (ntic != log->l_write_headq);
+
+		if (ntic != log->l_write_headq) {
+			if ((tic->t_flags & XLOG_TIC_IN_Q) == 0)
+				XLOG_INS_TICKETQ(log->l_write_headq, tic);
+
+			xlog_trace_loggrant(log, tic,
+				    "xlog_regrant_write_log_space: sleep 1");
+			XFS_STATS_INC(xs_sleep_logspace);
+			sv_wait(&tic->t_sema, PINOD|PLTWAIT,
+				&log->l_grant_lock, s);
+
+			/* If we're shutting down, this tic is already
+			 * off the queue */
+			if (XLOG_FORCED_SHUTDOWN(log)) {
+				s = GRANT_LOCK(log);
+				goto error_return;
+			}
+
+			xlog_trace_loggrant(log, tic,
+				    "xlog_regrant_write_log_space: wake 1");
+			xlog_grant_push_ail(log->l_mp, tic->t_unit_res);
+			s = GRANT_LOCK(log);
+		}
+	}
+
+	need_bytes = tic->t_unit_res;
+
+redo:
+	if (XLOG_FORCED_SHUTDOWN(log))
+		goto error_return;
+
+	free_bytes = xlog_space_left(log, log->l_grant_write_cycle,
+				     log->l_grant_write_bytes);
+	if (free_bytes < need_bytes) {
+		if ((tic->t_flags & XLOG_TIC_IN_Q) == 0)
+			XLOG_INS_TICKETQ(log->l_write_headq, tic);
+		XFS_STATS_INC(xs_sleep_logspace);
+		sv_wait(&tic->t_sema, PINOD|PLTWAIT, &log->l_grant_lock, s);
+
+		/* If we're shutting down, this tic is already off the queue */
+		if (XLOG_FORCED_SHUTDOWN(log)) {
+			s = GRANT_LOCK(log);
+			goto error_return;
+		}
+
+		xlog_trace_loggrant(log, tic,
+				    "xlog_regrant_write_log_space: wake 2");
+		xlog_grant_push_ail(log->l_mp, need_bytes);
+		s = GRANT_LOCK(log);
+		goto redo;
+	} else if (tic->t_flags & XLOG_TIC_IN_Q)
+		XLOG_DEL_TICKETQ(log->l_write_headq, tic);
+
+	XLOG_GRANT_ADD_SPACE(log, need_bytes, 'w'); /* we've got enough space */
+#ifdef DEBUG
+	tail_lsn = log->l_tail_lsn;
+	if (CYCLE_LSN(tail_lsn) != log->l_grant_write_cycle) {
+		ASSERT(log->l_grant_write_cycle-1 == CYCLE_LSN(tail_lsn));
+		ASSERT(log->l_grant_write_bytes <= BBTOB(BLOCK_LSN(tail_lsn)));
+	}
+#endif
+
+	xlog_trace_loggrant(log, tic, "xlog_regrant_write_log_space: exit");
+	xlog_verify_grant_head(log, 1);
+	GRANT_UNLOCK(log, s);
+	return (0);
+
+
+ error_return:
+	if (tic->t_flags & XLOG_TIC_IN_Q)
+		XLOG_DEL_TICKETQ(log->l_reserve_headq, tic);
+	xlog_trace_loggrant(log, tic, "xlog_regrant_write_log_space: err_ret");
+	/*
+	 * If we are failing, make sure the ticket doesn't have any
+	 * current reservations. We don't want to add this back when
+	 * the ticket/transaction gets cancelled.
+	 */
+	tic->t_curr_res = 0;
+	tic->t_cnt = 0; /* ungrant will give back unit_res * t_cnt. */
+	GRANT_UNLOCK(log, s);
+	return XFS_ERROR(EIO);
+}	/* xlog_regrant_write_log_space */
+
+
+/* The first cnt-1 times through here we don't need to
+ * move the grant write head because the permanent
+ * reservation has reserved cnt times the unit amount.
+ * Release part of current permanent unit reservation and
+ * reset current reservation to be one units worth.  Also
+ * move grant reservation head forward.
+ */
+STATIC void
+xlog_regrant_reserve_log_space(xlog_t	     *log,
+			       xlog_ticket_t *ticket)
+{
+	SPLDECL(s);
+
+	xlog_trace_loggrant(log, ticket,
+			    "xlog_regrant_reserve_log_space: enter");
+	if (ticket->t_cnt > 0)
+		ticket->t_cnt--;
+
+	s = GRANT_LOCK(log);
+	XLOG_GRANT_SUB_SPACE(log, ticket->t_curr_res, 'w');
+	XLOG_GRANT_SUB_SPACE(log, ticket->t_curr_res, 'r');
+	ticket->t_curr_res = ticket->t_unit_res;
+	xlog_trace_loggrant(log, ticket,
+			    "xlog_regrant_reserve_log_space: sub current res");
+	xlog_verify_grant_head(log, 1);
+
+	/* just return if we still have some of the pre-reserved space */
+	if (ticket->t_cnt > 0) {
+		GRANT_UNLOCK(log, s);
+		return;
+	}
+
+	XLOG_GRANT_ADD_SPACE(log, ticket->t_unit_res, 'r');
+	xlog_trace_loggrant(log, ticket,
+			    "xlog_regrant_reserve_log_space: exit");
+	xlog_verify_grant_head(log, 0);
+	GRANT_UNLOCK(log, s);
+	ticket->t_curr_res = ticket->t_unit_res;
+}	/* xlog_regrant_reserve_log_space */
+
+
+/*
+ * Give back the space left from a reservation.
+ *
+ * All the information we need to make a correct determination of space left
+ * is present.  For non-permanent reservations, things are quite easy.  The
+ * count should have been decremented to zero.  We only need to deal with the
+ * space remaining in the current reservation part of the ticket.  If the
+ * ticket contains a permanent reservation, there may be left over space which
+ * needs to be released.  A count of N means that N-1 refills of the current
+ * reservation can be done before we need to ask for more space.  The first
+ * one goes to fill up the first current reservation.  Once we run out of
+ * space, the count will stay at zero and the only space remaining will be
+ * in the current reservation field.
+ */
+STATIC void
+xlog_ungrant_log_space(xlog_t	     *log,
+		       xlog_ticket_t *ticket)
+{
+	SPLDECL(s);
+
+	if (ticket->t_cnt > 0)
+		ticket->t_cnt--;
+
+	s = GRANT_LOCK(log);
+	xlog_trace_loggrant(log, ticket, "xlog_ungrant_log_space: enter");
+
+	XLOG_GRANT_SUB_SPACE(log, ticket->t_curr_res, 'w');
+	XLOG_GRANT_SUB_SPACE(log, ticket->t_curr_res, 'r');
+
+	xlog_trace_loggrant(log, ticket, "xlog_ungrant_log_space: sub current");
+
+	/* If this is a permanent reservation ticket, we may be able to free
+	 * up more space based on the remaining count.
+	 */
+	if (ticket->t_cnt > 0) {
+		ASSERT(ticket->t_flags & XLOG_TIC_PERM_RESERV);
+		XLOG_GRANT_SUB_SPACE(log, ticket->t_unit_res*ticket->t_cnt,'w');
+		XLOG_GRANT_SUB_SPACE(log, ticket->t_unit_res*ticket->t_cnt,'r');
+	}
+
+	xlog_trace_loggrant(log, ticket, "xlog_ungrant_log_space: exit");
+	xlog_verify_grant_head(log, 1);
+	GRANT_UNLOCK(log, s);
+	xfs_log_move_tail(log->l_mp, 1);
+}	/* xlog_ungrant_log_space */
+
+
+/*
+ * Atomically put back used ticket.
+ */
+void
+xlog_state_put_ticket(xlog_t	    *log,
+		      xlog_ticket_t *tic)
+{
+	unsigned long s;
+
+	s = LOG_LOCK(log);
+	xlog_ticket_put(log, tic);
+	LOG_UNLOCK(log, s);
+}	/* xlog_state_put_ticket */
+
+/*
+ * Flush iclog to disk if this is the last reference to the given iclog and
+ * the WANT_SYNC bit is set.
+ *
+ * When this function is entered, the iclog is not necessarily in the
+ * WANT_SYNC state.  It may be sitting around waiting to get filled.
+ *
+ *
+ */
+int
+xlog_state_release_iclog(xlog_t		*log,
+			 xlog_in_core_t	*iclog)
+{
+	SPLDECL(s);
+	int		sync = 0;	/* do we sync? */
+
+	xlog_assign_tail_lsn(log->l_mp);
+
+	s = LOG_LOCK(log);
+
+	if (iclog->ic_state & XLOG_STATE_IOERROR) {
+		LOG_UNLOCK(log, s);
+		return XFS_ERROR(EIO);
+	}
+
+	ASSERT(iclog->ic_refcnt > 0);
+	ASSERT(iclog->ic_state == XLOG_STATE_ACTIVE ||
+	       iclog->ic_state == XLOG_STATE_WANT_SYNC);
+
+	if (--iclog->ic_refcnt == 0 &&
+	    iclog->ic_state == XLOG_STATE_WANT_SYNC) {
+		sync++;
+		iclog->ic_state = XLOG_STATE_SYNCING;
+		INT_SET(iclog->ic_header.h_tail_lsn, ARCH_CONVERT, log->l_tail_lsn);
+		xlog_verify_tail_lsn(log, iclog, log->l_tail_lsn);
+		/* cycle incremented when incrementing curr_block */
+	}
+
+	LOG_UNLOCK(log, s);
+
+	/*
+	 * We let the log lock go, so it's possible that we hit a log I/O
+	 * error or someother SHUTDOWN condition that marks the iclog
+	 * as XLOG_STATE_IOERROR before the bwrite. However, we know that
+	 * this iclog has consistent data, so we ignore IOERROR
+	 * flags after this point.
+	 */
+	if (sync) {
+		return xlog_sync(log, iclog);
+	}
+	return (0);
+
+}	/* xlog_state_release_iclog */
+
+
+/*
+ * This routine will mark the current iclog in the ring as WANT_SYNC
+ * and move the current iclog pointer to the next iclog in the ring.
+ * When this routine is called from xlog_state_get_iclog_space(), the
+ * exact size of the iclog has not yet been determined.  All we know is
+ * that every data block.  We have run out of space in this log record.
+ */
+STATIC void
+xlog_state_switch_iclogs(xlog_t		*log,
+			 xlog_in_core_t *iclog,
+			 int		eventual_size)
+{
+	ASSERT(iclog->ic_state == XLOG_STATE_ACTIVE);
+	if (!eventual_size)
+		eventual_size = iclog->ic_offset;
+	iclog->ic_state = XLOG_STATE_WANT_SYNC;
+	INT_SET(iclog->ic_header.h_prev_block, ARCH_CONVERT, log->l_prev_block);
+	log->l_prev_block = log->l_curr_block;
+	log->l_prev_cycle = log->l_curr_cycle;
+
+	/* roll log?: ic_offset changed later */
+	log->l_curr_block += BTOBB(eventual_size)+BTOBB(log->l_iclog_hsize);
+
+	/* Round up to next log-sunit */
+	if (XFS_SB_VERSION_HASLOGV2(&log->l_mp->m_sb) &&
+	    log->l_mp->m_sb.sb_logsunit > 1) {
+		__uint32_t sunit_bb = BTOBB(log->l_mp->m_sb.sb_logsunit);
+		log->l_curr_block = roundup(log->l_curr_block, sunit_bb);
+	}
+
+	if (log->l_curr_block >= log->l_logBBsize) {
+		log->l_curr_cycle++;
+		if (log->l_curr_cycle == XLOG_HEADER_MAGIC_NUM)
+			log->l_curr_cycle++;
+		log->l_curr_block -= log->l_logBBsize;
+		ASSERT(log->l_curr_block >= 0);
+	}
+	ASSERT(iclog == log->l_iclog);
+	log->l_iclog = iclog->ic_next;
+}	/* xlog_state_switch_iclogs */
+
+
+/*
+ * Write out all data in the in-core log as of this exact moment in time.
+ *
+ * Data may be written to the in-core log during this call.  However,
+ * we don't guarantee this data will be written out.  A change from past
+ * implementation means this routine will *not* write out zero length LRs.
+ *
+ * Basically, we try and perform an intelligent scan of the in-core logs.
+ * If we determine there is no flushable data, we just return.  There is no
+ * flushable data if:
+ *
+ *	1. the current iclog is active and has no data; the previous iclog
+ *		is in the active or dirty state.
+ *	2. the current iclog is drity, and the previous iclog is in the
+ *		active or dirty state.
+ *
+ * We may sleep (call psema) if:
+ *
+ *	1. the current iclog is not in the active nor dirty state.
+ *	2. the current iclog dirty, and the previous iclog is not in the
+ *		active nor dirty state.
+ *	3. the current iclog is active, and there is another thread writing
+ *		to this particular iclog.
+ *	4. a) the current iclog is active and has no other writers
+ *	   b) when we return from flushing out this iclog, it is still
+ *		not in the active nor dirty state.
+ */
+STATIC int
+xlog_state_sync_all(xlog_t *log, uint flags)
+{
+	xlog_in_core_t	*iclog;
+	xfs_lsn_t	lsn;
+	SPLDECL(s);
+
+	s = LOG_LOCK(log);
+
+	iclog = log->l_iclog;
+	if (iclog->ic_state & XLOG_STATE_IOERROR) {
+		LOG_UNLOCK(log, s);
+		return XFS_ERROR(EIO);
+	}
+
+	/* If the head iclog is not active nor dirty, we just attach
+	 * ourselves to the head and go to sleep.
+	 */
+	if (iclog->ic_state == XLOG_STATE_ACTIVE ||
+	    iclog->ic_state == XLOG_STATE_DIRTY) {
+		/*
+		 * If the head is dirty or (active and empty), then
+		 * we need to look at the previous iclog.  If the previous
+		 * iclog is active or dirty we are done.  There is nothing
+		 * to sync out.  Otherwise, we attach ourselves to the
+		 * previous iclog and go to sleep.
+		 */
+		if (iclog->ic_state == XLOG_STATE_DIRTY ||
+		    (iclog->ic_refcnt == 0 && iclog->ic_offset == 0)) {
+			iclog = iclog->ic_prev;
+			if (iclog->ic_state == XLOG_STATE_ACTIVE ||
+			    iclog->ic_state == XLOG_STATE_DIRTY)
+				goto no_sleep;
+			else
+				goto maybe_sleep;
+		} else {
+			if (iclog->ic_refcnt == 0) {
+				/* We are the only one with access to this
+				 * iclog.  Flush it out now.  There should
+				 * be a roundoff of zero to show that someone
+				 * has already taken care of the roundoff from
+				 * the previous sync.
+				 */
+				iclog->ic_refcnt++;
+				lsn = INT_GET(iclog->ic_header.h_lsn, ARCH_CONVERT);
+				xlog_state_switch_iclogs(log, iclog, 0);
+				LOG_UNLOCK(log, s);
+
+				if (xlog_state_release_iclog(log, iclog))
+					return XFS_ERROR(EIO);
+				s = LOG_LOCK(log);
+				if (INT_GET(iclog->ic_header.h_lsn, ARCH_CONVERT) == lsn &&
+				    iclog->ic_state != XLOG_STATE_DIRTY)
+					goto maybe_sleep;
+				else
+					goto no_sleep;
+			} else {
+				/* Someone else is writing to this iclog.
+				 * Use its call to flush out the data.  However,
+				 * the other thread may not force out this LR,
+				 * so we mark it WANT_SYNC.
+				 */
+				xlog_state_switch_iclogs(log, iclog, 0);
+				goto maybe_sleep;
+			}
+		}
+	}
+
+	/* By the time we come around again, the iclog could've been filled
+	 * which would give it another lsn.  If we have a new lsn, just
+	 * return because the relevant data has been flushed.
+	 */
+maybe_sleep:
+	if (flags & XFS_LOG_SYNC) {
+		/*
+		 * We must check if we're shutting down here, before
+		 * we wait, while we're holding the LOG_LOCK.
+		 * Then we check again after waking up, in case our
+		 * sleep was disturbed by a bad news.
+		 */
+		if (iclog->ic_state & XLOG_STATE_IOERROR) {
+			LOG_UNLOCK(log, s);
+			return XFS_ERROR(EIO);
+		}
+		XFS_STATS_INC(xs_log_force_sleep);
+		sv_wait(&iclog->ic_forcesema, PINOD, &log->l_icloglock, s);
+		/*
+		 * No need to grab the log lock here since we're
+		 * only deciding whether or not to return EIO
+		 * and the memory read should be atomic.
+		 */
+		if (iclog->ic_state & XLOG_STATE_IOERROR)
+			return XFS_ERROR(EIO);
+
+	} else {
+
+no_sleep:
+		LOG_UNLOCK(log, s);
+	}
+	return 0;
+}	/* xlog_state_sync_all */
+
+
+/*
+ * Used by code which implements synchronous log forces.
+ *
+ * Find in-core log with lsn.
+ *	If it is in the DIRTY state, just return.
+ *	If it is in the ACTIVE state, move the in-core log into the WANT_SYNC
+ *		state and go to sleep or return.
+ *	If it is in any other state, go to sleep or return.
+ *
+ * If filesystem activity goes to zero, the iclog will get flushed only by
+ * bdflush().
+ */
+int
+xlog_state_sync(xlog_t	  *log,
+		xfs_lsn_t lsn,
+		uint	  flags)
+{
+    xlog_in_core_t	*iclog;
+    int			already_slept = 0;
+    SPLDECL(s);
+
+
+try_again:
+    s = LOG_LOCK(log);
+    iclog = log->l_iclog;
+
+    if (iclog->ic_state & XLOG_STATE_IOERROR) {
+	    LOG_UNLOCK(log, s);
+	    return XFS_ERROR(EIO);
+    }
+
+    do {
+	if (INT_GET(iclog->ic_header.h_lsn, ARCH_CONVERT) != lsn) {
+	    iclog = iclog->ic_next;
+	    continue;
+	}
+
+	if (iclog->ic_state == XLOG_STATE_DIRTY) {
+		LOG_UNLOCK(log, s);
+		return 0;
+	}
+
+	if (iclog->ic_state == XLOG_STATE_ACTIVE) {
+		/*
+		 * We sleep here if we haven't already slept (e.g.
+		 * this is the first time we've looked at the correct
+		 * iclog buf) and the buffer before us is going to
+		 * be sync'ed. The reason for this is that if we
+		 * are doing sync transactions here, by waiting for
+		 * the previous I/O to complete, we can allow a few
+		 * more transactions into this iclog before we close
+		 * it down.
+		 *
+		 * Otherwise, we mark the buffer WANT_SYNC, and bump
+		 * up the refcnt so we can release the log (which drops
+		 * the ref count).  The state switch keeps new transaction
+		 * commits from using this buffer.  When the current commits
+		 * finish writing into the buffer, the refcount will drop to
+		 * zero and the buffer will go out then.
+		 */
+		if (!already_slept &&
+		    (iclog->ic_prev->ic_state & (XLOG_STATE_WANT_SYNC |
+						 XLOG_STATE_SYNCING))) {
+			ASSERT(!(iclog->ic_state & XLOG_STATE_IOERROR));
+			XFS_STATS_INC(xs_log_force_sleep);
+			sv_wait(&iclog->ic_prev->ic_writesema, PSWP,
+				&log->l_icloglock, s);
+			already_slept = 1;
+			goto try_again;
+		} else {
+			iclog->ic_refcnt++;
+			xlog_state_switch_iclogs(log, iclog, 0);
+			LOG_UNLOCK(log, s);
+			if (xlog_state_release_iclog(log, iclog))
+				return XFS_ERROR(EIO);
+			s = LOG_LOCK(log);
+		}
+	}
+
+	if ((flags & XFS_LOG_SYNC) && /* sleep */
+	    !(iclog->ic_state & (XLOG_STATE_ACTIVE | XLOG_STATE_DIRTY))) {
+
+		/*
+		 * Don't wait on the forcesema if we know that we've
+		 * gotten a log write error.
+		 */
+		if (iclog->ic_state & XLOG_STATE_IOERROR) {
+			LOG_UNLOCK(log, s);
+			return XFS_ERROR(EIO);
+		}
+		XFS_STATS_INC(xs_log_force_sleep);
+		sv_wait(&iclog->ic_forcesema, PSWP, &log->l_icloglock, s);
+		/*
+		 * No need to grab the log lock here since we're
+		 * only deciding whether or not to return EIO
+		 * and the memory read should be atomic.
+		 */
+		if (iclog->ic_state & XLOG_STATE_IOERROR)
+			return XFS_ERROR(EIO);
+	} else {		/* just return */
+		LOG_UNLOCK(log, s);
+	}
+	return 0;
+
+    } while (iclog != log->l_iclog);
+
+    LOG_UNLOCK(log, s);
+    return (0);
+}	/* xlog_state_sync */
+
+
+/*
+ * Called when we want to mark the current iclog as being ready to sync to
+ * disk.
+ */
+void
+xlog_state_want_sync(xlog_t *log, xlog_in_core_t *iclog)
+{
+	SPLDECL(s);
+
+	s = LOG_LOCK(log);
+
+	if (iclog->ic_state == XLOG_STATE_ACTIVE) {
+		xlog_state_switch_iclogs(log, iclog, 0);
+	} else {
+		ASSERT(iclog->ic_state &
+			(XLOG_STATE_WANT_SYNC|XLOG_STATE_IOERROR));
+	}
+
+	LOG_UNLOCK(log, s);
+}	/* xlog_state_want_sync */
+
+
+
+/*****************************************************************************
+ *
+ *		TICKET functions
+ *
+ *****************************************************************************
+ */
+
+/*
+ *	Algorithm doesn't take into account page size. ;-(
+ */
+STATIC void
+xlog_state_ticket_alloc(xlog_t *log)
+{
+	xlog_ticket_t	*t_list;
+	xlog_ticket_t	*next;
+	xfs_caddr_t	buf;
+	uint		i = (NBPP / sizeof(xlog_ticket_t)) - 2;
+	SPLDECL(s);
+
+	/*
+	 * The kmem_zalloc may sleep, so we shouldn't be holding the
+	 * global lock.  XXXmiken: may want to use zone allocator.
+	 */
+	buf = (xfs_caddr_t) kmem_zalloc(NBPP, KM_SLEEP);
+
+	s = LOG_LOCK(log);
+
+	/* Attach 1st ticket to Q, so we can keep track of allocated memory */
+	t_list = (xlog_ticket_t *)buf;
+	t_list->t_next = log->l_unmount_free;
+	log->l_unmount_free = t_list++;
+	log->l_ticket_cnt++;
+	log->l_ticket_tcnt++;
+
+	/* Next ticket becomes first ticket attached to ticket free list */
+	if (log->l_freelist != NULL) {
+		ASSERT(log->l_tail != NULL);
+		log->l_tail->t_next = t_list;
+	} else {
+		log->l_freelist = t_list;
+	}
+	log->l_ticket_cnt++;
+	log->l_ticket_tcnt++;
+
+	/* Cycle through rest of alloc'ed memory, building up free Q */
+	for ( ; i > 0; i--) {
+		next = t_list + 1;
+		t_list->t_next = next;
+		t_list = next;
+		log->l_ticket_cnt++;
+		log->l_ticket_tcnt++;
+	}
+	t_list->t_next = NULL;
+	log->l_tail = t_list;
+	LOG_UNLOCK(log, s);
+}	/* xlog_state_ticket_alloc */
+
+
+/*
+ * Put ticket into free list
+ *
+ * Assumption: log lock is held around this call.
+ */
+STATIC void
+xlog_ticket_put(xlog_t		*log,
+		xlog_ticket_t	*ticket)
+{
+	sv_destroy(&ticket->t_sema);
+
+	/*
+	 * Don't think caching will make that much difference.  It's
+	 * more important to make debug easier.
+	 */
+#if 0
+	/* real code will want to use LIFO for caching */
+	ticket->t_next = log->l_freelist;
+	log->l_freelist = ticket;
+	/* no need to clear fields */
+#else
+	/* When we debug, it is easier if tickets are cycled */
+	ticket->t_next     = NULL;
+	if (log->l_tail != 0) {
+		log->l_tail->t_next = ticket;
+	} else {
+		ASSERT(log->l_freelist == 0);
+		log->l_freelist = ticket;
+	}
+	log->l_tail	    = ticket;
+#endif /* DEBUG */
+	log->l_ticket_cnt++;
+}	/* xlog_ticket_put */
+
+
+/*
+ * Grab ticket off freelist or allocation some more
+ */
+xlog_ticket_t *
+xlog_ticket_get(xlog_t		*log,
+		int		unit_bytes,
+		int		cnt,
+		char		client,
+		uint		xflags)
+{
+	xlog_ticket_t	*tic;
+	uint		num_headers;
+	SPLDECL(s);
+
+ alloc:
+	if (log->l_freelist == NULL)
+		xlog_state_ticket_alloc(log);		/* potentially sleep */
+
+	s = LOG_LOCK(log);
+	if (log->l_freelist == NULL) {
+		LOG_UNLOCK(log, s);
+		goto alloc;
+	}
+	tic		= log->l_freelist;
+	log->l_freelist	= tic->t_next;
+	if (log->l_freelist == NULL)
+		log->l_tail = NULL;
+	log->l_ticket_cnt--;
+	LOG_UNLOCK(log, s);
+
+	/*
+	 * Permanent reservations have up to 'cnt'-1 active log operations
+	 * in the log.  A unit in this case is the amount of space for one
+	 * of these log operations.  Normal reservations have a cnt of 1
+	 * and their unit amount is the total amount of space required.
+	 *
+	 * The following lines of code account for non-transaction data
+	 * which occupy space in the on-disk log. 
+	 */
+
+	/* for start-rec */
+	unit_bytes += sizeof(xlog_op_header_t); 
+
+	/* for padding */
+	if (XFS_SB_VERSION_HASLOGV2(&log->l_mp->m_sb) &&
+		log->l_mp->m_sb.sb_logsunit > 1) {
+		/* log su roundoff */
+		unit_bytes += log->l_mp->m_sb.sb_logsunit;  
+	} else {
+		/* BB roundoff */
+		unit_bytes += BBSIZE;
+        }
+
+	/* for commit-rec */
+	unit_bytes += sizeof(xlog_op_header_t);
+ 
+	/* for LR headers */
+	num_headers = ((unit_bytes + log->l_iclog_size-1) >> log->l_iclog_size_log);
+	unit_bytes += log->l_iclog_hsize * num_headers;
+
+	tic->t_unit_res		= unit_bytes;
+	tic->t_curr_res		= unit_bytes;
+	tic->t_cnt		= cnt;
+	tic->t_ocnt		= cnt;
+	tic->t_tid		= (xlog_tid_t)((__psint_t)tic & 0xffffffff);
+	tic->t_clientid		= client;
+	tic->t_flags		= XLOG_TIC_INITED;
+	if (xflags & XFS_LOG_PERM_RESERV)
+		tic->t_flags |= XLOG_TIC_PERM_RESERV;
+	sv_init(&(tic->t_sema), SV_DEFAULT, "logtick");
+
+	return tic;
+}	/* xlog_ticket_get */
+
+
+/******************************************************************************
+ *
+ *		Log debug routines
+ *
+ ******************************************************************************
+ */
+#if defined(DEBUG) && !defined(XLOG_NOLOG)
+/*
+ * Make sure that the destination ptr is within the valid data region of
+ * one of the iclogs.  This uses backup pointers stored in a different
+ * part of the log in case we trash the log structure.
+ */
+void
+xlog_verify_dest_ptr(xlog_t     *log,
+		     __psint_t  ptr)
+{
+	int i;
+	int good_ptr = 0;
+
+	for (i=0; i < log->l_iclog_bufs; i++) {
+		if (ptr >= (__psint_t)log->l_iclog_bak[i] &&
+		    ptr <= (__psint_t)log->l_iclog_bak[i]+log->l_iclog_size)
+			good_ptr++;
+	}
+	if (! good_ptr)
+		xlog_panic("xlog_verify_dest_ptr: invalid ptr");
+}	/* xlog_verify_dest_ptr */
+
+STATIC void
+xlog_verify_grant_head(xlog_t *log, int equals)
+{
+    if (log->l_grant_reserve_cycle == log->l_grant_write_cycle) {
+	if (equals)
+	    ASSERT(log->l_grant_reserve_bytes >= log->l_grant_write_bytes);
+	else
+	    ASSERT(log->l_grant_reserve_bytes > log->l_grant_write_bytes);
+    } else {
+	ASSERT(log->l_grant_reserve_cycle-1 == log->l_grant_write_cycle);
+	ASSERT(log->l_grant_write_bytes >= log->l_grant_reserve_bytes);
+    }
+}	/* xlog_verify_grant_head */
+
+/* check if it will fit */
+STATIC void
+xlog_verify_tail_lsn(xlog_t	    *log,
+		     xlog_in_core_t *iclog,
+		     xfs_lsn_t	    tail_lsn)
+{
+    int blocks;
+
+    if (CYCLE_LSN(tail_lsn) == log->l_prev_cycle) {
+	blocks =
+	    log->l_logBBsize - (log->l_prev_block - BLOCK_LSN(tail_lsn));
+	if (blocks < BTOBB(iclog->ic_offset)+BTOBB(log->l_iclog_hsize))
+	    xlog_panic("xlog_verify_tail_lsn: ran out of log space");
+    } else {
+	ASSERT(CYCLE_LSN(tail_lsn)+1 == log->l_prev_cycle);
+
+	if (BLOCK_LSN(tail_lsn) == log->l_prev_block)
+	    xlog_panic("xlog_verify_tail_lsn: tail wrapped");
+
+	blocks = BLOCK_LSN(tail_lsn) - log->l_prev_block;
+	if (blocks < BTOBB(iclog->ic_offset) + 1)
+	    xlog_panic("xlog_verify_tail_lsn: ran out of log space");
+    }
+}	/* xlog_verify_tail_lsn */
+
+/*
+ * Perform a number of checks on the iclog before writing to disk.
+ *
+ * 1. Make sure the iclogs are still circular
+ * 2. Make sure we have a good magic number
+ * 3. Make sure we don't have magic numbers in the data
+ * 4. Check fields of each log operation header for:
+ *	A. Valid client identifier
+ *	B. tid ptr value falls in valid ptr space (user space code)
+ *	C. Length in log record header is correct according to the
+ *		individual operation headers within record.
+ * 5. When a bwrite will occur within 5 blocks of the front of the physical
+ *	log, check the preceding blocks of the physical log to make sure all
+ *	the cycle numbers agree with the current cycle number.
+ */
+STATIC void
+xlog_verify_iclog(xlog_t	 *log,
+		  xlog_in_core_t *iclog,
+		  int		 count,
+		  boolean_t	 syncing)
+{
+	xlog_op_header_t	*ophead;
+	xlog_in_core_t		*icptr;
+	xlog_in_core_2_t	*xhdr;
+	xfs_caddr_t		ptr;
+	xfs_caddr_t		base_ptr;
+	__psint_t		field_offset;
+	__uint8_t		clientid;
+	int			len, i, j, k, op_len;
+	int			idx;
+	SPLDECL(s);
+
+	/* check validity of iclog pointers */
+	s = LOG_LOCK(log);
+	icptr = log->l_iclog;
+	for (i=0; i < log->l_iclog_bufs; i++) {
+		if (icptr == 0)
+			xlog_panic("xlog_verify_iclog: invalid ptr");
+		icptr = icptr->ic_next;
+	}
+	if (icptr != log->l_iclog)
+		xlog_panic("xlog_verify_iclog: corrupt iclog ring");
+	LOG_UNLOCK(log, s);
+
+	/* check log magic numbers */
+	ptr = (xfs_caddr_t) &(iclog->ic_header);
+	if (INT_GET(*(uint *)ptr, ARCH_CONVERT) != XLOG_HEADER_MAGIC_NUM)
+		xlog_panic("xlog_verify_iclog: invalid magic num");
+
+	for (ptr += BBSIZE; ptr < ((xfs_caddr_t)&(iclog->ic_header))+count;
+	     ptr += BBSIZE) {
+		if (INT_GET(*(uint *)ptr, ARCH_CONVERT) == XLOG_HEADER_MAGIC_NUM)
+			xlog_panic("xlog_verify_iclog: unexpected magic num");
+	}
+
+	/* check fields */
+	len = INT_GET(iclog->ic_header.h_num_logops, ARCH_CONVERT);
+	ptr = iclog->ic_datap;
+	base_ptr = ptr;
+	ophead = (xlog_op_header_t *)ptr;
+	xhdr = (xlog_in_core_2_t *)&iclog->ic_header;
+	for (i = 0; i < len; i++) {
+		ophead = (xlog_op_header_t *)ptr;
+
+		/* clientid is only 1 byte */
+		field_offset = (__psint_t)
+			       ((xfs_caddr_t)&(ophead->oh_clientid) - base_ptr);
+		if (syncing == B_FALSE || (field_offset & 0x1ff)) {
+			clientid = ophead->oh_clientid;
+		} else {
+			idx = BTOBBT((xfs_caddr_t)&(ophead->oh_clientid) - iclog->ic_datap);
+			if (idx >= (XLOG_HEADER_CYCLE_SIZE / BBSIZE)) {
+				j = idx / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
+				k = idx % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
+				clientid = GET_CLIENT_ID(xhdr[j].hic_xheader.xh_cycle_data[k], ARCH_CONVERT);
+			} else {
+				clientid = GET_CLIENT_ID(iclog->ic_header.h_cycle_data[idx], ARCH_CONVERT);
+			}
+		}
+		if (clientid != XFS_TRANSACTION && clientid != XFS_LOG)
+			cmn_err(CE_WARN, "xlog_verify_iclog: invalid clientid %d op 0x%p offset 0x%x", clientid, ophead, field_offset);
+
+		/* check length */
+		field_offset = (__psint_t)
+			       ((xfs_caddr_t)&(ophead->oh_len) - base_ptr);
+		if (syncing == B_FALSE || (field_offset & 0x1ff)) {
+			op_len = INT_GET(ophead->oh_len, ARCH_CONVERT);
+		} else {
+			idx = BTOBBT((__psint_t)&ophead->oh_len -
+				    (__psint_t)iclog->ic_datap);
+			if (idx >= (XLOG_HEADER_CYCLE_SIZE / BBSIZE)) {
+				j = idx / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
+				k = idx % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
+				op_len = INT_GET(xhdr[j].hic_xheader.xh_cycle_data[k], ARCH_CONVERT);
+			} else {
+				op_len = INT_GET(iclog->ic_header.h_cycle_data[idx], ARCH_CONVERT);
+			}
+		}
+		ptr += sizeof(xlog_op_header_t) + op_len;
+	}
+}	/* xlog_verify_iclog */
+#endif /* DEBUG && !XLOG_NOLOG */
+
+/*
+ * Mark all iclogs IOERROR. LOG_LOCK is held by the caller.
+ */
+STATIC int
+xlog_state_ioerror(
+	xlog_t	*log)
+{
+	xlog_in_core_t	*iclog, *ic;
+
+	iclog = log->l_iclog;
+	if (! (iclog->ic_state & XLOG_STATE_IOERROR)) {
+		/*
+		 * Mark all the incore logs IOERROR.
+		 * From now on, no log flushes will result.
+		 */
+		ic = iclog;
+		do {
+			ic->ic_state = XLOG_STATE_IOERROR;
+			ic = ic->ic_next;
+		} while (ic != iclog);
+		return (0);
+	}
+	/*
+	 * Return non-zero, if state transition has already happened.
+	 */
+	return (1);
+}
+
+/*
+ * This is called from xfs_force_shutdown, when we're forcibly
+ * shutting down the filesystem, typically because of an IO error.
+ * Our main objectives here are to make sure that:
+ *	a. the filesystem gets marked 'SHUTDOWN' for all interested
+ *	   parties to find out, 'atomically'.
+ *	b. those who're sleeping on log reservations, pinned objects and
+ *	    other resources get woken up, and be told the bad news.
+ *	c. nothing new gets queued up after (a) and (b) are done.
+ *	d. if !logerror, flush the iclogs to disk, then seal them off
+ *	   for business.
+ */
+int
+xfs_log_force_umount(
+	struct xfs_mount	*mp,
+	int			logerror)
+{
+	xlog_ticket_t	*tic;
+	xlog_t		*log;
+	int		retval;
+	SPLDECL(s);
+	SPLDECL(s2);
+
+	log = mp->m_log;
+
+	/*
+	 * If this happens during log recovery, don't worry about
+	 * locking; the log isn't open for business yet.
+	 */
+	if (!log ||
+	    log->l_flags & XLOG_ACTIVE_RECOVERY) {
+		mp->m_flags |= XFS_MOUNT_FS_SHUTDOWN;
+		XFS_BUF_DONE(mp->m_sb_bp);
+		return (0);
+	}
+
+	/*
+	 * Somebody could've already done the hard work for us.
+	 * No need to get locks for this.
+	 */
+	if (logerror && log->l_iclog->ic_state & XLOG_STATE_IOERROR) {
+		ASSERT(XLOG_FORCED_SHUTDOWN(log));
+		return (1);
+	}
+	retval = 0;
+	/*
+	 * We must hold both the GRANT lock and the LOG lock,
+	 * before we mark the filesystem SHUTDOWN and wake
+	 * everybody up to tell the bad news.
+	 */
+	s = GRANT_LOCK(log);
+	s2 = LOG_LOCK(log);
+	mp->m_flags |= XFS_MOUNT_FS_SHUTDOWN;
+	XFS_BUF_DONE(mp->m_sb_bp);
+	/*
+	 * This flag is sort of redundant because of the mount flag, but
+	 * it's good to maintain the separation between the log and the rest
+	 * of XFS.
+	 */
+	log->l_flags |= XLOG_IO_ERROR;
+
+	/*
+	 * If we hit a log error, we want to mark all the iclogs IOERROR
+	 * while we're still holding the loglock.
+	 */
+	if (logerror)
+		retval = xlog_state_ioerror(log);
+	LOG_UNLOCK(log, s2);
+
+	/*
+	 * We don't want anybody waiting for log reservations
+	 * after this. That means we have to wake up everybody
+	 * queued up on reserve_headq as well as write_headq.
+	 * In addition, we make sure in xlog_{re}grant_log_space
+	 * that we don't enqueue anything once the SHUTDOWN flag
+	 * is set, and this action is protected by the GRANTLOCK.
+	 */
+	if ((tic = log->l_reserve_headq)) {
+		do {
+			sv_signal(&tic->t_sema);
+			tic = tic->t_next;
+		} while (tic != log->l_reserve_headq);
+	}
+
+	if ((tic = log->l_write_headq)) {
+		do {
+			sv_signal(&tic->t_sema);
+			tic = tic->t_next;
+		} while (tic != log->l_write_headq);
+	}
+	GRANT_UNLOCK(log, s);
+
+	if (! (log->l_iclog->ic_state & XLOG_STATE_IOERROR)) {
+		ASSERT(!logerror);
+		/*
+		 * Force the incore logs to disk before shutting the
+		 * log down completely.
+		 */
+		xlog_state_sync_all(log, XFS_LOG_FORCE|XFS_LOG_SYNC);
+		s2 = LOG_LOCK(log);
+		retval = xlog_state_ioerror(log);
+		LOG_UNLOCK(log, s2);
+	}
+	/*
+	 * Wake up everybody waiting on xfs_log_force.
+	 * Callback all log item committed functions as if the
+	 * log writes were completed.
+	 */
+	xlog_state_do_callback(log, XFS_LI_ABORTED, NULL);
+
+#ifdef XFSERRORDEBUG
+	{
+		xlog_in_core_t	*iclog;
+
+		s = LOG_LOCK(log);
+		iclog = log->l_iclog;
+		do {
+			ASSERT(iclog->ic_callback == 0);
+			iclog = iclog->ic_next;
+		} while (iclog != log->l_iclog);
+		LOG_UNLOCK(log, s);
+	}
+#endif
+	/* return non-zero if log IOERROR transition had already happened */
+	return (retval);
+}
+
+int
+xlog_iclogs_empty(xlog_t *log)
+{
+	xlog_in_core_t	*iclog;
+
+	iclog = log->l_iclog;
+	do {
+		/* endianness does not matter here, zero is zero in
+		 * any language.
+		 */
+		if (iclog->ic_header.h_num_logops)
+			return(0);
+		iclog = iclog->ic_next;
+	} while (iclog != log->l_iclog);
+	return(1);
+}