/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms 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.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_error.h"
#include "xfs_log_priv.h"
#include "xfs_buf_item.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_log_recover.h"
#include "xfs_trans_priv.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_rw.h"
#include "xfs_trace.h"

kmem_zone_t	*xfs_log_ticket_zone;

/* Local miscellaneous function prototypes */
STATIC int	 xlog_commit_record(struct log *log, struct xlog_ticket *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(struct log *log, atomic64_t *head);
STATIC int	 xlog_sync(xlog_t *log, xlog_in_core_t *iclog);
STATIC void	 xlog_dealloc_log(xlog_t *log);

/* 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 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 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(struct log	*log,
				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);

#if defined(DEBUG)
STATIC void	xlog_verify_dest_ptr(xlog_t *log, char *ptr);
STATIC void	xlog_verify_grant_tail(struct log *log);
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_tail(a)
#define xlog_verify_iclog(a,b,c,d)
#define xlog_verify_tail_lsn(a,b,c)
#endif

STATIC int	xlog_iclogs_empty(xlog_t *log);

static void
xlog_grant_sub_space(
	struct log	*log,
	atomic64_t	*head,
	int		bytes)
{
	int64_t	head_val = atomic64_read(head);
	int64_t new, old;

	do {
		int	cycle, space;

		xlog_crack_grant_head_val(head_val, &cycle, &space);

		space -= bytes;
		if (space < 0) {
			space += log->l_logsize;
			cycle--;
		}

		old = head_val;
		new = xlog_assign_grant_head_val(cycle, space);
		head_val = atomic64_cmpxchg(head, old, new);
	} while (head_val != old);
}

static void
xlog_grant_add_space(
	struct log	*log,
	atomic64_t	*head,
	int		bytes)
{
	int64_t	head_val = atomic64_read(head);
	int64_t new, old;

	do {
		int		tmp;
		int		cycle, space;

		xlog_crack_grant_head_val(head_val, &cycle, &space);

		tmp = log->l_logsize - space;
		if (tmp > bytes)
			space += bytes;
		else {
			space = bytes - tmp;
			cycle++;
		}

		old = head_val;
		new = xlog_assign_grant_head_val(cycle, space);
		head_val = atomic64_cmpxchg(head, old, new);
	} while (head_val != old);
}

static void
xlog_tic_reset_res(xlog_ticket_t *tic)
{
	tic->t_res_num = 0;
	tic->t_res_arr_sum = 0;
	tic->t_res_num_ophdrs = 0;
}

static void
xlog_tic_add_region(xlog_ticket_t *tic, uint len, uint type)
{
	if (tic->t_res_num == XLOG_TIC_LEN_MAX) {
		/* add to overflow and start again */
		tic->t_res_o_flow += tic->t_res_arr_sum;
		tic->t_res_num = 0;
		tic->t_res_arr_sum = 0;
	}

	tic->t_res_arr[tic->t_res_num].r_len = len;
	tic->t_res_arr[tic->t_res_num].r_type = type;
	tic->t_res_arr_sum += len;
	tic->t_res_num++;
}

/*
 * 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(
	struct xfs_mount	*mp,
	struct xlog_ticket	*ticket,
	struct xlog_in_core	**iclog,
	uint			flags)
{
	struct log		*log = mp->m_log;
	xfs_lsn_t		lsn = 0;

	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(log, ticket, 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)) {
		trace_xfs_log_done_nonperm(log, ticket);

		/*
		 * Release ticket if not permanent reservation or a specific
		 * request has been made to release a permanent reservation.
		 */
		xlog_ungrant_log_space(log, ticket);
		xfs_log_ticket_put(ticket);
	} else {
		trace_xfs_log_done_perm(log, ticket);

		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.
		 */
		ticket->t_flags |= XLOG_TIC_INITED;
	}

	return lsn;
}

/*
 * 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(
	struct xfs_mount	*mp,
	struct xlog_in_core	*iclog,
	xfs_log_callback_t	*cb)
{
	int	abortflg;

	spin_lock(&iclog->ic_callback_lock);
	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);
	}
	spin_unlock(&iclog->ic_callback_lock);
	return abortflg;
}

int
xfs_log_release_iclog(
	struct xfs_mount	*mp,
	struct xlog_in_core	*iclog)
{
	if (xlog_state_release_iclog(mp->m_log, iclog)) {
		xfs_force_shutdown(mp, SHUTDOWN_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(
	struct xfs_mount	*mp,
	int		 	unit_bytes,
	int		 	cnt,
	struct xlog_ticket	**ticket,
	__uint8_t	 	client,
	uint		 	flags,
	uint		 	t_type)
{
	struct log		*log = mp->m_log;
	struct xlog_ticket	*internal_ticket;
	int			retval = 0;

	ASSERT(client == XFS_TRANSACTION || client == XFS_LOG);

	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 = *ticket;

		/*
		 * this is a new transaction on the ticket, so we need to
		 * change the transaction ID so that the next transaction has a
		 * different TID in the log. Just add one to the existing tid
		 * so that we can see chains of rolling transactions in the log
		 * easily.
		 */
		internal_ticket->t_tid++;

		trace_xfs_log_reserve(log, internal_ticket);

		xlog_grant_push_ail(log, 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_alloc(log, unit_bytes, cnt,
						  client, flags,
						  KM_SLEEP|KM_MAYFAIL);
		if (!internal_ticket)
			return XFS_ERROR(ENOMEM);
		internal_ticket->t_trans_type = t_type;
		*ticket = internal_ticket;

		trace_xfs_log_reserve(log, internal_ticket);

		xlog_grant_push_ail(log,
				    (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)
{
	int		error;

	if (!(mp->m_flags & XFS_MOUNT_NORECOVERY))
		xfs_notice(mp, "Mounting Filesystem");
	else {
		xfs_notice(mp,
"Mounting filesystem in no-recovery mode.  Filesystem will be inconsistent.");
		ASSERT(mp->m_flags & XFS_MOUNT_RDONLY);
	}

	mp->m_log = xlog_alloc_log(mp, log_target, blk_offset, num_bblks);
	if (IS_ERR(mp->m_log)) {
		error = -PTR_ERR(mp->m_log);
		goto out;
	}

	/*
	 * Initialize the AIL now we have a log.
	 */
	error = xfs_trans_ail_init(mp);
	if (error) {
		xfs_warn(mp, "AIL initialisation failed: error %d", error);
		goto out_free_log;
	}
	mp->m_log->l_ailp = mp->m_ail;

	/*
	 * skip log recovery on a norecovery mount.  pretend it all
	 * just worked.
	 */
	if (!(mp->m_flags & XFS_MOUNT_NORECOVERY)) {
		int	readonly = (mp->m_flags & XFS_MOUNT_RDONLY);

		if (readonly)
			mp->m_flags &= ~XFS_MOUNT_RDONLY;

		error = xlog_recover(mp->m_log);

		if (readonly)
			mp->m_flags |= XFS_MOUNT_RDONLY;
		if (error) {
			xfs_warn(mp, "log mount/recovery failed: error %d",
				error);
			goto out_destroy_ail;
		}
	}

	/* Normal transactions can now occur */
	mp->m_log->l_flags &= ~XLOG_ACTIVE_RECOVERY;

	/*
	 * Now the log has been fully initialised and we know were our
	 * space grant counters are, we can initialise the permanent ticket
	 * needed for delayed logging to work.
	 */
	xlog_cil_init_post_recovery(mp->m_log);

	return 0;

out_destroy_ail:
	xfs_trans_ail_destroy(mp);
out_free_log:
	xlog_dealloc_log(mp->m_log);
out:
	return error;
}

/*
 * 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	error;

	if (!(mp->m_flags & XFS_MOUNT_NORECOVERY))
		error = xlog_recover_finish(mp->m_log);
	else {
		error = 0;
		ASSERT(mp->m_flags & XFS_MOUNT_RDONLY);
	}

	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
	xlog_ticket_t	*tic = NULL;
	xfs_lsn_t	 lsn;
	int		 error;

	/*
	 * Don't write out unmount record on read-only mounts.
	 * Or, if we are doing a forced umount (typically because of IO errors).
	 */
	if (mp->m_flags & XFS_MOUNT_RDONLY)
		return 0;

	error = _xfs_log_force(mp, XFS_LOG_SYNC, NULL);
	ASSERT(error || !(XLOG_FORCED_SHUTDOWN(log)));

#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))) {
		error = xfs_log_reserve(mp, 600, 1, &tic,
					XFS_LOG, 0, XLOG_UNMOUNT_REC_TYPE);
		if (!error) {
			/* 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 = {
				.magic = XLOG_UNMOUNT_TYPE,
			};
			struct xfs_log_iovec reg = {
				.i_addr = &magic,
				.i_len = sizeof(magic),
				.i_type = XLOG_REG_TYPE_UNMOUNT,
			};
			struct xfs_log_vec vec = {
				.lv_niovecs = 1,
				.lv_iovecp = &reg,
			};

			/* remove inited flag */
			tic->t_flags = 0;
			error = xlog_write(log, &vec, 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_alert(mp, "%s: unmount record failed", __func__);


		spin_lock(&log->l_icloglock);
		iclog = log->l_iclog;
		atomic_inc(&iclog->ic_refcnt);
		xlog_state_want_sync(log, iclog);
		spin_unlock(&log->l_icloglock);
		error = xlog_state_release_iclog(log, iclog);

		spin_lock(&log->l_icloglock);
		if (!(iclog->ic_state == XLOG_STATE_ACTIVE ||
		      iclog->ic_state == XLOG_STATE_DIRTY)) {
			if (!XLOG_FORCED_SHUTDOWN(log)) {
				xlog_wait(&iclog->ic_force_wait,
							&log->l_icloglock);
			} else {
				spin_unlock(&log->l_icloglock);
			}
		} else {
			spin_unlock(&log->l_icloglock);
		}
		if (tic) {
			trace_xfs_log_umount_write(log, tic);
			xlog_ungrant_log_space(log, tic);
			xfs_log_ticket_put(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/Os 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..
		 */
		spin_lock(&log->l_icloglock);
		iclog = log->l_iclog;
		atomic_inc(&iclog->ic_refcnt);

		xlog_state_want_sync(log, iclog);
		spin_unlock(&log->l_icloglock);
		error =  xlog_state_release_iclog(log, iclog);

		spin_lock(&log->l_icloglock);

		if ( ! (   iclog->ic_state == XLOG_STATE_ACTIVE
			|| iclog->ic_state == XLOG_STATE_DIRTY
			|| iclog->ic_state == XLOG_STATE_IOERROR) ) {

				xlog_wait(&iclog->ic_force_wait,
							&log->l_icloglock);
		} else {
			spin_unlock(&log->l_icloglock);
		}
	}

	return error;
}	/* xfs_log_unmount_write */

/*
 * Deallocate log structures for unmount/relocation.
 *
 * We need to stop the aild from running before we destroy
 * and deallocate the log as the aild references the log.
 */
void
xfs_log_unmount(xfs_mount_t *mp)
{
	xfs_trans_ail_destroy(mp);
	xlog_dealloc_log(mp->m_log);
}

void
xfs_log_item_init(
	struct xfs_mount	*mp,
	struct xfs_log_item	*item,
	int			type,
	struct xfs_item_ops	*ops)
{
	item->li_mountp = mp;
	item->li_ailp = mp->m_ail;
	item->li_type = type;
	item->li_ops = ops;
	item->li_lv = NULL;

	INIT_LIST_HEAD(&item->li_ail);
	INIT_LIST_HEAD(&item->li_cil);
}

/*
 * 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(). However, it is important
 * to note that the transaction reservation code makes an assumption about the
 * number of log headers a transaction requires that may be violated if you
 * don't pass all the transaction vectors in one call....
 */
int
xfs_log_write(
	struct xfs_mount	*mp,
	struct xfs_log_iovec	reg[],
	int			nentries,
	struct xlog_ticket	*tic,
	xfs_lsn_t		*start_lsn)
{
	struct log		*log = mp->m_log;
	int			error;
	struct xfs_log_vec	vec = {
		.lv_niovecs = nentries,
		.lv_iovecp = reg,
	};

	if (XLOG_FORCED_SHUTDOWN(log))
		return XFS_ERROR(EIO);

	error = xlog_write(log, &vec, tic, start_lsn, NULL, 0);
	if (error)
		xfs_force_shutdown(mp, SHUTDOWN_LOG_IO_ERROR);
	return error;
}

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;

	if (XLOG_FORCED_SHUTDOWN(log))
		return;

	if (tail_lsn == 0)
		tail_lsn = atomic64_read(&log->l_last_sync_lsn);

	/* tail_lsn == 1 implies that we weren't passed a valid value.  */
	if (tail_lsn != 1)
		atomic64_set(&log->l_tail_lsn, tail_lsn);

	if (!list_empty_careful(&log->l_writeq)) {
#ifdef DEBUG
		if (log->l_flags & XLOG_ACTIVE_RECOVERY)
			panic("Recovery problem");
#endif
		spin_lock(&log->l_grant_write_lock);
		free_bytes = xlog_space_left(log, &log->l_grant_write_head);
		list_for_each_entry(tic, &log->l_writeq, t_queue) {
			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;
			trace_xfs_log_regrant_write_wake_up(log, tic);
			wake_up(&tic->t_wait);
		}
		spin_unlock(&log->l_grant_write_lock);
	}

	if (!list_empty_careful(&log->l_reserveq)) {
#ifdef DEBUG
		if (log->l_flags & XLOG_ACTIVE_RECOVERY)
			panic("Recovery problem");
#endif
		spin_lock(&log->l_grant_reserve_lock);
		free_bytes = xlog_space_left(log, &log->l_grant_reserve_head);
		list_for_each_entry(tic, &log->l_reserveq, t_queue) {
			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;
			trace_xfs_log_grant_wake_up(log, tic);
			wake_up(&tic->t_wait);
		}
		spin_unlock(&log->l_grant_reserve_lock);
	}
}

/*
 * Determine if we have a transaction that has gone to disk
 * that needs to be covered. To begin the transition to the idle state
 * firstly the log needs to be idle (no AIL and nothing in the iclogs).
 * If we are then in a state where covering is needed, the caller is informed
 * that dummy transactions are required to move the log into the idle state.
 *
 * Because this is called as part of the sync process, we should also indicate
 * that dummy transactions should be issued in anything but the covered or
 * idle states. This ensures that the log tail is accurately reflected in
 * the log at the end of the sync, hence if a crash occurrs avoids replay
 * of transactions where the metadata is already on disk.
 */
int
xfs_log_need_covered(xfs_mount_t *mp)
{
	int		needed = 0;
	xlog_t		*log = mp->m_log;

	if (!xfs_fs_writable(mp))
		return 0;

	spin_lock(&log->l_icloglock);
	switch (log->l_covered_state) {
	case XLOG_STATE_COVER_DONE:
	case XLOG_STATE_COVER_DONE2:
	case XLOG_STATE_COVER_IDLE:
		break;
	case XLOG_STATE_COVER_NEED:
	case XLOG_STATE_COVER_NEED2:
		if (!xfs_ail_min_lsn(log->l_ailp) &&
		    xlog_iclogs_empty(log)) {
			if (log->l_covered_state == XLOG_STATE_COVER_NEED)
				log->l_covered_state = XLOG_STATE_COVER_DONE;
			else
				log->l_covered_state = XLOG_STATE_COVER_DONE2;
		}
		/* FALLTHRU */
	default:
		needed = 1;
		break;
	}
	spin_unlock(&log->l_icloglock);
	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(
	struct xfs_mount	*mp)
{
	xfs_lsn_t		tail_lsn;
	struct log		*log = mp->m_log;

	tail_lsn = xfs_ail_min_lsn(mp->m_ail);
	if (!tail_lsn)
		tail_lsn = atomic64_read(&log->l_last_sync_lsn);

	atomic64_set(&log->l_tail_lsn, tail_lsn);
	return 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.
 */
STATIC int
xlog_space_left(
	struct log	*log,
	atomic64_t	*head)
{
	int		free_bytes;
	int		tail_bytes;
	int		tail_cycle;
	int		head_cycle;
	int		head_bytes;

	xlog_crack_grant_head(head, &head_cycle, &head_bytes);
	xlog_crack_atomic_lsn(&log->l_tail_lsn, &tail_cycle, &tail_bytes);
	tail_bytes = BBTOB(tail_bytes);
	if (tail_cycle == head_cycle && head_bytes >= tail_bytes)
		free_bytes = log->l_logsize - (head_bytes - tail_bytes);
	else if (tail_cycle + 1 < head_cycle)
		return 0;
	else if (tail_cycle < head_cycle) {
		ASSERT(tail_cycle == (head_cycle - 1));
		free_bytes = tail_bytes - head_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_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, head_cycle, head_bytes);
		ASSERT(0);
		free_bytes = log->l_logsize;
	}
	return free_bytes;
}


/*
 * 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 = bp->b_fspriv;
	xlog_t		*l = iclog->ic_log;
	int		aborted = 0;

	/*
	 * 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, SHUTDOWN_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;
	}

	/* log I/O is always issued ASYNC */
	ASSERT(XFS_BUF_ISASYNC(bp));
	xlog_state_done_syncing(iclog, aborted);
	/*
	 * do not reference the buffer (bp) here as we could race
	 * with it being freed after writing the unmount record to the
	 * log.
	 */

}	/* xlog_iodone */

/*
 * Return size of each in-core log record buffer.
 *
 * All machines get 8 x 32kB buffers by default, unless tuned otherwise.
 *
 * 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 (mp->m_logbufs <= 0)
		log->l_iclog_bufs = XLOG_MAX_ICLOGS;
	else
		log->l_iclog_bufs = mp->m_logbufs;

	/*
	 * Buffer size passed in from mount system call.
	 */
	if (mp->m_logbsize > 0) {
		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;
		}
		goto done;
	}

	/* All machines use 32kB buffers by default. */
	log->l_iclog_size = XLOG_BIG_RECORD_BSIZE;
	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;

done:
	/* are we being asked to make the sizes selected above visible? */
	if (mp->m_logbufs == 0)
		mp->m_logbufs = log->l_iclog_bufs;
	if (mp->m_logbsize == 0)
		mp->m_logbsize = log->l_iclog_size;
}	/* 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			error = ENOMEM;
	uint			log2_size = 0;

	log = kmem_zalloc(sizeof(xlog_t), KM_MAYFAIL);
	if (!log) {
		xfs_warn(mp, "Log allocation failed: No memory!");
		goto out;
	}

	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;
	/* log->l_tail_lsn = 0x100000000LL; cycle = 1; current block = 0 */
	xlog_assign_atomic_lsn(&log->l_tail_lsn, 1, 0);
	xlog_assign_atomic_lsn(&log->l_last_sync_lsn, 1, 0);
	log->l_curr_cycle  = 1;	    /* 0 is bad since this is initial value */
	xlog_assign_grant_head(&log->l_grant_reserve_head, 1, 0);
	xlog_assign_grant_head(&log->l_grant_write_head, 1, 0);
	INIT_LIST_HEAD(&log->l_reserveq);
	INIT_LIST_HEAD(&log->l_writeq);
	spin_lock_init(&log->l_grant_reserve_lock);
	spin_lock_init(&log->l_grant_write_lock);

	error = EFSCORRUPTED;
	if (xfs_sb_version_hassector(&mp->m_sb)) {
	        log2_size = mp->m_sb.sb_logsectlog;
		if (log2_size < BBSHIFT) {
			xfs_warn(mp, "Log sector size too small (0x%x < 0x%x)",
				log2_size, BBSHIFT);
			goto out_free_log;
		}

	        log2_size -= BBSHIFT;
		if (log2_size > mp->m_sectbb_log) {
			xfs_warn(mp, "Log sector size too large (0x%x > 0x%x)",
				log2_size, mp->m_sectbb_log);
			goto out_free_log;
		}

		/* for larger sector sizes, must have v2 or external log */
		if (log2_size && log->l_logBBstart > 0 &&
			    !xfs_sb_version_haslogv2(&mp->m_sb)) {
			xfs_warn(mp,
		"log sector size (0x%x) invalid for configuration.",
				log2_size);
			goto out_free_log;
		}
	}
	log->l_sectBBsize = 1 << log2_size;

	xlog_get_iclog_buffer_size(mp, log);

	error = ENOMEM;
	bp = xfs_buf_get_empty(log->l_iclog_size, mp->m_logdev_targp);
	if (!bp)
		goto out_free_log;
	bp->b_iodone = xlog_iodone;
	ASSERT(xfs_buf_islocked(bp));
	log->l_xbuf = bp;

	spin_lock_init(&log->l_icloglock);
	init_waitqueue_head(&log->l_flush_wait);

	/* 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.
	 */
	ASSERT(log->l_iclog_size >= 4096);
	for (i=0; i < log->l_iclog_bufs; i++) {
		*iclogp = kmem_zalloc(sizeof(xlog_in_core_t), KM_MAYFAIL);
		if (!*iclogp)
			goto out_free_iclog;

		iclog = *iclogp;
		iclog->ic_prev = prev_iclog;
		prev_iclog = iclog;

		bp = xfs_buf_get_uncached(mp->m_logdev_targp,
						log->l_iclog_size, 0);
		if (!bp)
			goto out_free_iclog;

		bp->b_iodone = xlog_iodone;
		iclog->ic_bp = bp;
		iclog->ic_data = bp->b_addr;
#ifdef DEBUG
		log->l_iclog_bak[i] = (xfs_caddr_t)&(iclog->ic_header);
#endif
		head = &iclog->ic_header;
		memset(head, 0, sizeof(xlog_rec_header_t));
		head->h_magicno = cpu_to_be32(XLOG_HEADER_MAGIC_NUM);
		head->h_version = cpu_to_be32(
			xfs_sb_version_haslogv2(&log->l_mp->m_sb) ? 2 : 1);
		head->h_size = cpu_to_be32(log->l_iclog_size);
		/* new fields */
		head->h_fmt = cpu_to_be32(XLOG_FMT);
		memcpy(&head->h_fs_uuid, &mp->m_sb.sb_uuid, sizeof(uuid_t));

		iclog->ic_size = XFS_BUF_SIZE(bp) - log->l_iclog_hsize;
		iclog->ic_state = XLOG_STATE_ACTIVE;
		iclog->ic_log = log;
		atomic_set(&iclog->ic_refcnt, 0);
		spin_lock_init(&iclog->ic_callback_lock);
		iclog->ic_callback_tail = &(iclog->ic_callback);
		iclog->ic_datap = (char *)iclog->ic_data + log->l_iclog_hsize;

		ASSERT(xfs_buf_islocked(iclog->ic_bp));
		init_waitqueue_head(&iclog->ic_force_wait);
		init_waitqueue_head(&iclog->ic_write_wait);

		iclogp = &iclog->ic_next;
	}
	*iclogp = log->l_iclog;			/* complete ring */
	log->l_iclog->ic_prev = prev_iclog;	/* re-write 1st prev ptr */

	error = xlog_cil_init(log);
	if (error)
		goto out_free_iclog;
	return log;

out_free_iclog:
	for (iclog = log->l_iclog; iclog; iclog = prev_iclog) {
		prev_iclog = iclog->ic_next;
		if (iclog->ic_bp)
			xfs_buf_free(iclog->ic_bp);
		kmem_free(iclog);
	}
	spinlock_destroy(&log->l_icloglock);
	xfs_buf_free(log->l_xbuf);
out_free_log:
	kmem_free(log);
out:
	return ERR_PTR(-error);
}	/* 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(
	struct log		*log,
	struct xlog_ticket	*ticket,
	struct xlog_in_core	**iclog,
	xfs_lsn_t		*commitlsnp)
{
	struct xfs_mount *mp = log->l_mp;
	int	error;
	struct xfs_log_iovec reg = {
		.i_addr = NULL,
		.i_len = 0,
		.i_type = XLOG_REG_TYPE_COMMIT,
	};
	struct xfs_log_vec vec = {
		.lv_niovecs = 1,
		.lv_iovecp = &reg,
	};

	ASSERT_ALWAYS(iclog);
	error = xlog_write(log, &vec, ticket, commitlsnp, iclog,
					XLOG_COMMIT_TRANS);
	if (error)
		xfs_force_shutdown(mp, SHUTDOWN_LOG_IO_ERROR);
	return error;
}

/*
 * 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.
 */
STATIC void
xlog_grant_push_ail(
	struct log	*log,
	int		need_bytes)
{
	xfs_lsn_t	threshold_lsn = 0;
	xfs_lsn_t	last_sync_lsn;
	int		free_blocks;
	int		free_bytes;
	int		threshold_block;
	int		threshold_cycle;
	int		free_threshold;

	ASSERT(BTOBB(need_bytes) < log->l_logBBsize);

	free_bytes = xlog_space_left(log, &log->l_grant_reserve_head);
	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)
		return;

	xlog_crack_atomic_lsn(&log->l_tail_lsn, &threshold_cycle,
						&threshold_block);
	threshold_block += free_threshold;
	if (threshold_block >= log->l_logBBsize) {
		threshold_block -= log->l_logBBsize;
		threshold_cycle += 1;
	}
	threshold_lsn = xlog_assign_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. Use a snapshot of the last sync lsn
	 * so that it doesn't change between the compare and the set.
	 */
	last_sync_lsn = atomic64_read(&log->l_last_sync_lsn);
	if (XFS_LSN_CMP(threshold_lsn, last_sync_lsn) > 0)
		threshold_lsn = last_sync_lsn;

	/*
	 * 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 (!XLOG_FORCED_SHUTDOWN(log))
		xfs_ail_push(log->l_ailp, threshold_lsn);
}

/*
 * 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(
	struct xfs_buf		*bp)
{
	struct xlog_in_core	*iclog = bp->b_fspriv;

	if (iclog->ic_state & XLOG_STATE_IOERROR) {
		xfs_buf_ioerror(bp, EIO);
		XFS_BUF_STALE(bp);
		xfs_buf_ioend(bp, 0);
		/*
		 * It would seem logical to return EIO here, but we rely on
		 * the log state machine to propagate I/O errors instead of
		 * doing it here.
		 */
		return 0;
	}

	xfs_buf_iorequest(bp);
	return 0;
}

/*
 * 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().
 */

STATIC 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;
	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;
	int		v2 = xfs_sb_version_haslogv2(&log->l_mp->m_sb);

	XFS_STATS_INC(xs_log_writes);
	ASSERT(atomic_read(&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 */
	xlog_grant_add_space(log, &log->l_grant_reserve_head, roundoff);
	xlog_grant_add_space(log, &log->l_grant_write_head, roundoff);

	/* put cycle number in every block */
	xlog_pack_data(log, iclog, roundoff); 

	/* real byte length */
	if (v2) {
		iclog->ic_header.h_len =
			cpu_to_be32(iclog->ic_offset + roundoff);
	} else {
		iclog->ic_header.h_len =
			cpu_to_be32(iclog->ic_offset);
	}

	bp = iclog->ic_bp;
	XFS_BUF_SET_ADDR(bp, BLOCK_LSN(be64_to_cpu(iclog->ic_header.h_lsn)));

	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_COUNT(bp, count);
	bp->b_fspriv = iclog;
	XFS_BUF_ZEROFLAGS(bp);
	XFS_BUF_ASYNC(bp);
	bp->b_flags |= XBF_SYNCIO;

	if (log->l_mp->m_flags & XFS_MOUNT_BARRIER) {
		bp->b_flags |= XBF_FUA;

		/*
		 * Flush the data device before flushing the log to make
		 * sure all meta data written back from the AIL actually made
		 * it to disk before stamping the new log tail LSN into the
		 * log buffer.  For an external log we need to issue the
		 * flush explicitly, and unfortunately synchronously here;
		 * for an internal log we can simply use the block layer
		 * state machine for preflushes.
		 */
		if (log->l_mp->m_logdev_targp != log->l_mp->m_ddev_targp)
			xfs_blkdev_issue_flush(log->l_mp->m_ddev_targp);
		else
			bp->b_flags |= XBF_FLUSH;
	}

	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 = xlog_bdstrat(bp))) {
		xfs_ioerror_alert("xlog_sync", log->l_mp, bp,
				  XFS_BUF_ADDR(bp));
		return error;
	}
	if (split) {
		bp = iclog->ic_log->l_xbuf;
		XFS_BUF_SET_ADDR(bp, 0);	     /* logical 0 */
		xfs_buf_associate_memory(bp,
				(char *)&iclog->ic_header + count, split);
		bp->b_fspriv = iclog;
		XFS_BUF_ZEROFLAGS(bp);
		XFS_BUF_ASYNC(bp);
		bp->b_flags |= XBF_SYNCIO;
		if (log->l_mp->m_flags & XFS_MOUNT_BARRIER)
			bp->b_flags |= XBF_FUA;
		dptr = bp->b_addr;
		/*
		 * 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) {
			be32_add_cpu((__be32 *)dptr, 1);
			if (be32_to_cpu(*(__be32 *)dptr) == XLOG_HEADER_MAGIC_NUM)
				be32_add_cpu((__be32 *)dptr, 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 doesn't start at block #0 */
		XFS_BUF_SET_ADDR(bp, XFS_BUF_ADDR(bp) + log->l_logBBstart);
		XFS_BUF_WRITE(bp);
		if ((error = xlog_bdstrat(bp))) {
			xfs_ioerror_alert("xlog_sync (split)", log->l_mp,
					  bp, XFS_BUF_ADDR(bp));
			return error;
		}
	}
	return 0;
}	/* xlog_sync */


/*
 * Deallocate a log structure
 */
STATIC void
xlog_dealloc_log(xlog_t *log)
{
	xlog_in_core_t	*iclog, *next_iclog;
	int		i;

	xlog_cil_destroy(log);

	/*
	 * always need to ensure that the extra buffer does not point to memory
	 * owned by another log buffer before we free it.
	 */
	xfs_buf_set_empty(log->l_xbuf, log->l_iclog_size);
	xfs_buf_free(log->l_xbuf);

	iclog = log->l_iclog;
	for (i=0; i<log->l_iclog_bufs; i++) {
		xfs_buf_free(iclog->ic_bp);
		next_iclog = iclog->ic_next;
		kmem_free(iclog);
		iclog = next_iclog;
	}
	spinlock_destroy(&log->l_icloglock);

	log->l_mp->m_log = NULL;
	kmem_free(log);
}	/* xlog_dealloc_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)
{
	spin_lock(&log->l_icloglock);

	be32_add_cpu(&iclog->ic_header.h_num_logops, record_cnt);
	iclog->ic_offset += copy_bytes;

	spin_unlock(&log->l_icloglock);
}	/* xlog_state_finish_copy */




/*
 * print out info relating to regions written which consume
 * the reservation
 */
void
xlog_print_tic_res(
	struct xfs_mount	*mp,
	struct xlog_ticket	*ticket)
{
	uint i;
	uint ophdr_spc = ticket->t_res_num_ophdrs * (uint)sizeof(xlog_op_header_t);

	/* match with XLOG_REG_TYPE_* in xfs_log.h */
	static char *res_type_str[XLOG_REG_TYPE_MAX] = {
	    "bformat",
	    "bchunk",
	    "efi_format",
	    "efd_format",
	    "iformat",
	    "icore",
	    "iext",
	    "ibroot",
	    "ilocal",
	    "iattr_ext",
	    "iattr_broot",
	    "iattr_local",
	    "qformat",
	    "dquot",
	    "quotaoff",
	    "LR header",
	    "unmount",
	    "commit",
	    "trans header"
	};
	static char *trans_type_str[XFS_TRANS_TYPE_MAX] = {
	    "SETATTR_NOT_SIZE",
	    "SETATTR_SIZE",
	    "INACTIVE",
	    "CREATE",
	    "CREATE_TRUNC",
	    "TRUNCATE_FILE",
	    "REMOVE",
	    "LINK",
	    "RENAME",
	    "MKDIR",
	    "RMDIR",
	    "SYMLINK",
	    "SET_DMATTRS",
	    "GROWFS",
	    "STRAT_WRITE",
	    "DIOSTRAT",
	    "WRITE_SYNC",
	    "WRITEID",
	    "ADDAFORK",
	    "ATTRINVAL",
	    "ATRUNCATE",
	    "ATTR_SET",
	    "ATTR_RM",
	    "ATTR_FLAG",
	    "CLEAR_AGI_BUCKET",
	    "QM_SBCHANGE",
	    "DUMMY1",
	    "DUMMY2",
	    "QM_QUOTAOFF",
	    "QM_DQALLOC",
	    "QM_SETQLIM",
	    "QM_DQCLUSTER",
	    "QM_QINOCREATE",
	    "QM_QUOTAOFF_END",
	    "SB_UNIT",
	    "FSYNC_TS",
	    "GROWFSRT_ALLOC",
	    "GROWFSRT_ZERO",
	    "GROWFSRT_FREE",
	    "SWAPEXT"
	};

	xfs_warn(mp,
		"xfs_log_write: reservation summary:\n"
		"  trans type  = %s (%u)\n"
		"  unit res    = %d bytes\n"
		"  current res = %d bytes\n"
		"  total reg   = %u bytes (o/flow = %u bytes)\n"
		"  ophdrs      = %u (ophdr space = %u bytes)\n"
		"  ophdr + reg = %u bytes\n"
		"  num regions = %u\n",
		((ticket->t_trans_type <= 0 ||
		  ticket->t_trans_type > XFS_TRANS_TYPE_MAX) ?
		  "bad-trans-type" : trans_type_str[ticket->t_trans_type-1]),
		ticket->t_trans_type,
		ticket->t_unit_res,
		ticket->t_curr_res,
		ticket->t_res_arr_sum, ticket->t_res_o_flow,
		ticket->t_res_num_ophdrs, ophdr_spc,
		ticket->t_res_arr_sum +
		ticket->t_res_o_flow + ophdr_spc,
		ticket->t_res_num);

	for (i = 0; i < ticket->t_res_num; i++) {
		uint r_type = ticket->t_res_arr[i].r_type;
		xfs_warn(mp, "region[%u]: %s - %u bytes\n", i,
			    ((r_type <= 0 || r_type > XLOG_REG_TYPE_MAX) ?
			    "bad-rtype" : res_type_str[r_type-1]),
			    ticket->t_res_arr[i].r_len);
	}

	xfs_alert_tag(mp, XFS_PTAG_LOGRES,
		"xfs_log_write: reservation ran out. Need to up reservation");
	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
}

/*
 * Calculate the potential space needed by the log vector.  Each region gets
 * its own xlog_op_header_t and may need to be double word aligned.
 */
static int
xlog_write_calc_vec_length(
	struct xlog_ticket	*ticket,
	struct xfs_log_vec	*log_vector)
{
	struct xfs_log_vec	*lv;
	int			headers = 0;
	int			len = 0;
	int			i;

	/* acct for start rec of xact */
	if (ticket->t_flags & XLOG_TIC_INITED)
		headers++;

	for (lv = log_vector; lv; lv = lv->lv_next) {
		headers += lv->lv_niovecs;

		for (i = 0; i < lv->lv_niovecs; i++) {
			struct xfs_log_iovec	*vecp = &lv->lv_iovecp[i];

			len += vecp->i_len;
			xlog_tic_add_region(ticket, vecp->i_len, vecp->i_type);
		}
	}

	ticket->t_res_num_ophdrs += headers;
	len += headers * sizeof(struct xlog_op_header);

	return len;
}

/*
 * 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.
 */
static int
xlog_write_start_rec(
	struct xlog_op_header	*ophdr,
	struct xlog_ticket	*ticket)
{
	if (!(ticket->t_flags & XLOG_TIC_INITED))
		return 0;

	ophdr->oh_tid	= cpu_to_be32(ticket->t_tid);
	ophdr->oh_clientid = ticket->t_clientid;
	ophdr->oh_len = 0;
	ophdr->oh_flags = XLOG_START_TRANS;
	ophdr->oh_res2 = 0;

	ticket->t_flags &= ~XLOG_TIC_INITED;

	return sizeof(struct xlog_op_header);
}

static xlog_op_header_t *
xlog_write_setup_ophdr(
	struct log		*log,
	struct xlog_op_header	*ophdr,
	struct xlog_ticket	*ticket,
	uint			flags)
{
	ophdr->oh_tid = cpu_to_be32(ticket->t_tid);
	ophdr->oh_clientid = ticket->t_clientid;
	ophdr->oh_res2 = 0;

	/* are we copying a commit or unmount record? */
	ophdr->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 (ophdr->oh_clientid)  {
	case XFS_TRANSACTION:
	case XFS_VOLUME:
	case XFS_LOG:
		break;
	default:
		xfs_warn(log->l_mp,
			"Bad XFS transaction clientid 0x%x in ticket 0x%p",
			ophdr->oh_clientid, ticket);
		return NULL;
	}

	return ophdr;
}

/*
 * Set up the parameters of the region copy into the log. This has
 * to handle region write split across multiple log buffers - this
 * state is kept external to this function so that this code can
 * can be written in an obvious, self documenting manner.
 */
static int
xlog_write_setup_copy(
	struct xlog_ticket	*ticket,
	struct xlog_op_header	*ophdr,
	int			space_available,
	int			space_required,
	int			*copy_off,
	int			*copy_len,
	int			*last_was_partial_copy,
	int			*bytes_consumed)
{
	int			still_to_copy;

	still_to_copy = space_required - *bytes_consumed;
	*copy_off = *bytes_consumed;

	if (still_to_copy <= space_available) {
		/* write of region completes here */
		*copy_len = still_to_copy;
		ophdr->oh_len = cpu_to_be32(*copy_len);
		if (*last_was_partial_copy)
			ophdr->oh_flags |= (XLOG_END_TRANS|XLOG_WAS_CONT_TRANS);
		*last_was_partial_copy = 0;
		*bytes_consumed = 0;
		return 0;
	}

	/* partial write of region, needs extra log op header reservation */
	*copy_len = space_available;
	ophdr->oh_len = cpu_to_be32(*copy_len);
	ophdr->oh_flags |= XLOG_CONTINUE_TRANS;
	if (*last_was_partial_copy)
		ophdr->oh_flags |= XLOG_WAS_CONT_TRANS;
	*bytes_consumed += *copy_len;
	(*last_was_partial_copy)++;

	/* account for new log op header */
	ticket->t_curr_res -= sizeof(struct xlog_op_header);
	ticket->t_res_num_ophdrs++;

	return sizeof(struct xlog_op_header);
}

static int
xlog_write_copy_finish(
	struct log		*log,
	struct xlog_in_core	*iclog,
	uint			flags,
	int			*record_cnt,
	int			*data_cnt,
	int			*partial_copy,
	int			*partial_copy_len,
	int			log_offset,
	struct xlog_in_core	**commit_iclog)
{
	if (*partial_copy) {
		/*
		 * This iclog has already been marked WANT_SYNC by
		 * xlog_state_get_iclog_space.
		 */
		xlog_state_finish_copy(log, iclog, *record_cnt, *data_cnt);
		*record_cnt = 0;
		*data_cnt = 0;
		return xlog_state_release_iclog(log, iclog);
	}

	*partial_copy = 0;
	*partial_copy_len = 0;

	if (iclog->ic_size - log_offset <= sizeof(xlog_op_header_t)) {
		/* no more space in this iclog - push it. */
		xlog_state_finish_copy(log, iclog, *record_cnt, *data_cnt);
		*record_cnt = 0;
		*data_cnt = 0;

		spin_lock(&log->l_icloglock);
		xlog_state_want_sync(log, iclog);
		spin_unlock(&log->l_icloglock);

		if (!commit_iclog)
			return xlog_state_release_iclog(log, iclog);
		ASSERT(flags & XLOG_COMMIT_TRANS);
		*commit_iclog = iclog;
	}

	return 0;
}

/*
 * 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 cu…