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

• Lines: 597
• Date: 2004-02-18 05:36:32.000000000 -0800
• Orig file: linux-2.4.24/fs/xfs/xfs_trans_ail.c
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.24/fs/xfs/xfs_trans_ail.c linux-2.4.25/fs/xfs/xfs_trans_ail.c
@@ -0,0 +1,596 @@
+/*
+ * Copyright (c) 2000-2002 Silicon Graphics, Inc.  All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * Further, this software is distributed without any warranty that it is
+ * free of the rightful claim of any third person regarding infringement
+ * or the like.  Any license provided herein, whether implied or
+ * otherwise, applies only to this software file.  Patent licenses, if
+ * any, provided herein do not apply to combinations of this program with
+ * other software, or any other product whatsoever.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write the Free Software Foundation, Inc., 59
+ * Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
+ * Mountain View, CA  94043, or:
+ *
+ * http://www.sgi.com
+ *
+ * For further information regarding this notice, see:
+ *
+ * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
+ */
+
+#include "xfs.h"
+#include "xfs_macros.h"
+#include "xfs_types.h"
+#include "xfs_inum.h"
+#include "xfs_log.h"
+#include "xfs_trans.h"
+#include "xfs_sb.h"
+#include "xfs_dir.h"
+#include "xfs_dmapi.h"
+#include "xfs_mount.h"
+#include "xfs_trans_priv.h"
+#include "xfs_error.h"
+
+STATIC void xfs_ail_insert(xfs_ail_entry_t *, xfs_log_item_t *);
+STATIC xfs_log_item_t * xfs_ail_delete(xfs_ail_entry_t *, xfs_log_item_t *);
+STATIC xfs_log_item_t * xfs_ail_min(xfs_ail_entry_t *);
+STATIC xfs_log_item_t * xfs_ail_next(xfs_ail_entry_t *, xfs_log_item_t *);
+
+#ifdef XFSDEBUG
+STATIC void xfs_ail_check(xfs_ail_entry_t *);
+#else
+#define	xfs_ail_check(a)
+#endif /* XFSDEBUG */
+
+
+/*
+ * This is called by the log manager code to determine the LSN
+ * of the tail of the log.  This is exactly the LSN of the first
+ * item in the AIL.  If the AIL is empty, then this function
+ * returns 0.
+ *
+ * We need the AIL lock in order to get a coherent read of the
+ * lsn of the last item in the AIL.
+ */
+xfs_lsn_t
+xfs_trans_tail_ail(
+	xfs_mount_t	*mp)
+{
+	xfs_lsn_t	lsn;
+	xfs_log_item_t	*lip;
+	SPLDECL(s);
+
+	AIL_LOCK(mp,s);
+	lip = xfs_ail_min(&(mp->m_ail));
+	if (lip == NULL) {
+		lsn = (xfs_lsn_t)0;
+	} else {
+		lsn = lip->li_lsn;
+	}
+	AIL_UNLOCK(mp, s);
+
+	return lsn;
+}
+
+/*
+ * xfs_trans_push_ail
+ *
+ * This routine is called to move the tail of the AIL
+ * forward.  It does this by trying to flush items in the AIL
+ * whose lsns are below the given threshold_lsn.
+ *
+ * The routine returns the lsn of the tail of the log.
+ */
+xfs_lsn_t
+xfs_trans_push_ail(
+	xfs_mount_t		*mp,
+	xfs_lsn_t		threshold_lsn)
+{
+	xfs_lsn_t		lsn;
+	xfs_log_item_t		*lip;
+	int			gen;
+	int			restarts;
+	int			lock_result;
+	int			flush_log;
+	SPLDECL(s);
+
+#define	XFS_TRANS_PUSH_AIL_RESTARTS	10
+
+	AIL_LOCK(mp,s);
+	lip = xfs_trans_first_ail(mp, &gen);
+	if (lip == NULL || XFS_FORCED_SHUTDOWN(mp)) {
+		/*
+		 * Just return if the AIL is empty.
+		 */
+		AIL_UNLOCK(mp, s);
+		return (xfs_lsn_t)0;
+	}
+
+	XFS_STATS_INC(xs_push_ail);
+
+	/*
+	 * While the item we are looking at is below the given threshold
+	 * try to flush it out.  Make sure to limit the number of times
+	 * we allow xfs_trans_next_ail() to restart scanning from the
+	 * beginning of the list.  We'd like not to stop until we've at least
+	 * tried to push on everything in the AIL with an LSN less than
+	 * the given threshold. However, we may give up before that if
+	 * we realize that we've been holding the AIL_LOCK for 'too long',
+	 * blocking interrupts. Currently, too long is < 500us roughly.
+	 */
+	flush_log = 0;
+	restarts = 0;
+	while (((restarts < XFS_TRANS_PUSH_AIL_RESTARTS) &&
+		(XFS_LSN_CMP(lip->li_lsn, threshold_lsn) < 0))) {
+		/*
+		 * If we can lock the item without sleeping, unlock
+		 * the AIL lock and flush the item.  Then re-grab the
+		 * AIL lock so we can look for the next item on the
+		 * AIL.  Since we unlock the AIL while we flush the
+		 * item, the next routine may start over again at the
+		 * the beginning of the list if anything has changed.
+		 * That is what the generation count is for.
+		 *
+		 * If we can't lock the item, either its holder will flush
+		 * it or it is already being flushed or it is being relogged.
+		 * In any of these case it is being taken care of and we
+		 * can just skip to the next item in the list.
+		 */
+		lock_result = IOP_TRYLOCK(lip);
+		switch (lock_result) {
+		      case XFS_ITEM_SUCCESS:
+			AIL_UNLOCK(mp, s);
+			XFS_STATS_INC(xs_push_ail_success);
+			IOP_PUSH(lip);
+			AIL_LOCK(mp,s);
+			break;
+
+		      case XFS_ITEM_PUSHBUF:
+			AIL_UNLOCK(mp, s);
+			XFS_STATS_INC(xs_push_ail_pushbuf);
+#ifdef XFSRACEDEBUG
+			delay_for_intr();
+			delay(300);
+#endif
+			ASSERT(lip->li_ops->iop_pushbuf);
+			ASSERT(lip);
+			IOP_PUSHBUF(lip);
+			AIL_LOCK(mp,s);
+			break;
+
+		      case XFS_ITEM_PINNED:
+			XFS_STATS_INC(xs_push_ail_pinned);
+			flush_log = 1;
+			break;
+
+		      case XFS_ITEM_LOCKED:
+			XFS_STATS_INC(xs_push_ail_locked);
+			break;
+
+		      case XFS_ITEM_FLUSHING:
+			XFS_STATS_INC(xs_push_ail_flushing);
+			break;
+
+		      default:
+			ASSERT(0);
+			break;
+		}
+
+		lip = xfs_trans_next_ail(mp, lip, &gen, &restarts);
+		if (lip == NULL) {
+			break;
+		}
+		if (XFS_FORCED_SHUTDOWN(mp)) {
+			/*
+			 * Just return if we shut down during the last try.
+			 */
+			AIL_UNLOCK(mp, s);
+			return (xfs_lsn_t)0;
+		}
+
+	}
+
+	if (flush_log) {
+		/*
+		 * If something we need to push out was pinned, then
+		 * push out the log so it will become unpinned and
+		 * move forward in the AIL.
+		 */
+		AIL_UNLOCK(mp, s);
+		XFS_STATS_INC(xs_push_ail_flush);
+		xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
+		AIL_LOCK(mp, s);
+	}
+
+	lip = xfs_ail_min(&(mp->m_ail));
+	if (lip == NULL) {
+		lsn = (xfs_lsn_t)0;
+	} else {
+		lsn = lip->li_lsn;
+	}
+
+	AIL_UNLOCK(mp, s);
+	return lsn;
+}	/* xfs_trans_push_ail */
+
+
+/*
+ * This is to be called when an item is unlocked that may have
+ * been in the AIL.  It will wake up the first member of the AIL
+ * wait list if this item's unlocking might allow it to progress.
+ * If the item is in the AIL, then we need to get the AIL lock
+ * while doing our checking so we don't race with someone going
+ * to sleep waiting for this event in xfs_trans_push_ail().
+ */
+void
+xfs_trans_unlocked_item(
+	xfs_mount_t	*mp,
+	xfs_log_item_t	*lip)
+{
+	xfs_log_item_t	*min_lip;
+
+	/*
+	 * If we're forcibly shutting down, we may have
+	 * unlocked log items arbitrarily. The last thing
+	 * we want to do is to move the tail of the log
+	 * over some potentially valid data.
+	 */
+	if (!(lip->li_flags & XFS_LI_IN_AIL) ||
+	    XFS_FORCED_SHUTDOWN(mp)) {
+		return;
+	}
+
+	/*
+	 * This is the one case where we can call into xfs_ail_min()
+	 * without holding the AIL lock because we only care about the
+	 * case where we are at the tail of the AIL.  If the object isn't
+	 * at the tail, it doesn't matter what result we get back.  This
+	 * is slightly racy because since we were just unlocked, we could
+	 * go to sleep between the call to xfs_ail_min and the call to
+	 * xfs_log_move_tail, have someone else lock us, commit to us disk,
+	 * move us out of the tail of the AIL, and then we wake up.  However,
+	 * the call to xfs_log_move_tail() doesn't do anything if there's
+	 * not enough free space to wake people up so we're safe calling it.
+	 */
+	min_lip = xfs_ail_min(&mp->m_ail);
+
+	if (min_lip == lip)
+		xfs_log_move_tail(mp, 1);
+}	/* xfs_trans_unlocked_item */
+
+
+/*
+ * Update the position of the item in the AIL with the new
+ * lsn.  If it is not yet in the AIL, add it.  Otherwise, move
+ * it to its new position by removing it and re-adding it.
+ *
+ * Wakeup anyone with an lsn less than the item's lsn.  If the item
+ * we move in the AIL is the minimum one, update the tail lsn in the
+ * log manager.
+ *
+ * Increment the AIL's generation count to indicate that the tree
+ * has changed.
+ *
+ * This function must be called with the AIL lock held.  The lock
+ * is dropped before returning, so the caller must pass in the
+ * cookie returned by AIL_LOCK.
+ */
+void
+xfs_trans_update_ail(
+	xfs_mount_t	*mp,
+	xfs_log_item_t	*lip,
+	xfs_lsn_t	lsn,
+	unsigned long	s)
+{
+	xfs_ail_entry_t		*ailp;
+	xfs_log_item_t		*dlip=NULL;
+	xfs_log_item_t		*mlip;	/* ptr to minimum lip */
+
+	ailp = &(mp->m_ail);
+	mlip = xfs_ail_min(ailp);
+
+	if (lip->li_flags & XFS_LI_IN_AIL) {
+		dlip = xfs_ail_delete(ailp, lip);
+		ASSERT(dlip == lip);
+	} else {
+		lip->li_flags |= XFS_LI_IN_AIL;
+	}
+
+	lip->li_lsn = lsn;
+
+	xfs_ail_insert(ailp, lip);
+	mp->m_ail_gen++;
+
+	if (mlip == dlip) {
+		mlip = xfs_ail_min(&(mp->m_ail));
+		AIL_UNLOCK(mp, s);
+		xfs_log_move_tail(mp, mlip->li_lsn);
+	} else {
+		AIL_UNLOCK(mp, s);
+	}
+
+
+}	/* xfs_trans_update_ail */
+
+/*
+ * Delete the given item from the AIL.  It must already be in
+ * the AIL.
+ *
+ * Wakeup anyone with an lsn less than item's lsn.    If the item
+ * we delete in the AIL is the minimum one, update the tail lsn in the
+ * log manager.
+ *
+ * Clear the IN_AIL flag from the item, reset its lsn to 0, and
+ * bump the AIL's generation count to indicate that the tree
+ * has changed.
+ *
+ * This function must be called with the AIL lock held.  The lock
+ * is dropped before returning, so the caller must pass in the
+ * cookie returned by AIL_LOCK.
+ */
+void
+xfs_trans_delete_ail(
+	xfs_mount_t	*mp,
+	xfs_log_item_t	*lip,
+	unsigned long	s)
+{
+	xfs_ail_entry_t		*ailp;
+	xfs_log_item_t		*dlip;
+	xfs_log_item_t		*mlip;
+
+	if (lip->li_flags & XFS_LI_IN_AIL) {
+		ailp = &(mp->m_ail);
+		mlip = xfs_ail_min(ailp);
+		dlip = xfs_ail_delete(ailp, lip);
+		ASSERT(dlip == lip);
+
+
+		lip->li_flags &= ~XFS_LI_IN_AIL;
+		lip->li_lsn = 0;
+		mp->m_ail_gen++;
+
+		if (mlip == dlip) {
+			mlip = xfs_ail_min(&(mp->m_ail));
+			AIL_UNLOCK(mp, s);
+			xfs_log_move_tail(mp, (mlip ? mlip->li_lsn : 0));
+		} else {
+			AIL_UNLOCK(mp, s);
+		}
+	}
+	else {
+		/*
+		 * If the file system is not being shutdown, we are in
+		 * serious trouble if we get to this stage.
+		 */
+		if (XFS_FORCED_SHUTDOWN(mp))
+			AIL_UNLOCK(mp, s);
+		else {
+			xfs_cmn_err(XFS_PTAG_AILDELETE, CE_ALERT, mp,
+				"xfs_trans_delete_ail: attempting to delete a log item that is not in the AIL");
+			xfs_force_shutdown(mp, XFS_CORRUPT_INCORE);
+			AIL_UNLOCK(mp, s);
+		}
+	}
+}
+
+
+
+/*
+ * Return the item in the AIL with the smallest lsn.
+ * Return the current tree generation number for use
+ * in calls to xfs_trans_next_ail().
+ */
+xfs_log_item_t *
+xfs_trans_first_ail(
+	xfs_mount_t	*mp,
+	int		*gen)
+{
+	xfs_log_item_t	*lip;
+
+	lip = xfs_ail_min(&(mp->m_ail));
+	*gen = (int)mp->m_ail_gen;
+
+	return (lip);
+}
+
+/*
+ * If the generation count of the tree has not changed since the
+ * caller last took something from the AIL, then return the elmt
+ * in the tree which follows the one given.  If the count has changed,
+ * then return the minimum elmt of the AIL and bump the restarts counter
+ * if one is given.
+ */
+xfs_log_item_t *
+xfs_trans_next_ail(
+	xfs_mount_t	*mp,
+	xfs_log_item_t	*lip,
+	int		*gen,
+	int		*restarts)
+{
+	xfs_log_item_t	*nlip;
+
+	ASSERT(mp && lip && gen);
+	if (mp->m_ail_gen == *gen) {
+		nlip = xfs_ail_next(&(mp->m_ail), lip);
+	} else {
+		nlip = xfs_ail_min(&(mp->m_ail));
+		*gen = (int)mp->m_ail_gen;
+		if (restarts != NULL) {
+			XFS_STATS_INC(xs_push_ail_restarts);
+			(*restarts)++;
+		}
+	}
+
+	return (nlip);
+}
+
+
+/*
+ * The active item list (AIL) is a doubly linked list of log
+ * items sorted by ascending lsn.  The base of the list is
+ * a forw/back pointer pair embedded in the xfs mount structure.
+ * The base is initialized with both pointers pointing to the
+ * base.  This case always needs to be distinguished, because
+ * the base has no lsn to look at.  We almost always insert
+ * at the end of the list, so on inserts we search from the
+ * end of the list to find where the new item belongs.
+ */
+
+/*
+ * Initialize the doubly linked list to point only to itself.
+ */
+void
+xfs_trans_ail_init(
+	xfs_mount_t	*mp)
+{
+	mp->m_ail.ail_forw = (xfs_log_item_t*)&(mp->m_ail);
+	mp->m_ail.ail_back = (xfs_log_item_t*)&(mp->m_ail);
+}
+
+/*
+ * Insert the given log item into the AIL.
+ * We almost always insert at the end of the list, so on inserts
+ * we search from the end of the list to find where the
+ * new item belongs.
+ */
+STATIC void
+xfs_ail_insert(
+	xfs_ail_entry_t	*base,
+	xfs_log_item_t	*lip)
+/* ARGSUSED */
+{
+	xfs_log_item_t	*next_lip;
+
+	/*
+	 * If the list is empty, just insert the item.
+	 */
+	if (base->ail_back == (xfs_log_item_t*)base) {
+		base->ail_forw = lip;
+		base->ail_back = lip;
+		lip->li_ail.ail_forw = (xfs_log_item_t*)base;
+		lip->li_ail.ail_back = (xfs_log_item_t*)base;
+		return;
+	}
+
+	next_lip = base->ail_back;
+	while ((next_lip != (xfs_log_item_t*)base) &&
+	       (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) > 0)) {
+		next_lip = next_lip->li_ail.ail_back;
+	}
+	ASSERT((next_lip == (xfs_log_item_t*)base) ||
+	       (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0));
+	lip->li_ail.ail_forw = next_lip->li_ail.ail_forw;
+	lip->li_ail.ail_back = next_lip;
+	next_lip->li_ail.ail_forw = lip;
+	lip->li_ail.ail_forw->li_ail.ail_back = lip;
+
+	xfs_ail_check(base);
+	return;
+}
+
+/*
+ * Delete the given item from the AIL.  Return a pointer to the item.
+ */
+/*ARGSUSED*/
+STATIC xfs_log_item_t *
+xfs_ail_delete(
+	xfs_ail_entry_t	*base,
+	xfs_log_item_t	*lip)
+/* ARGSUSED */
+{
+	lip->li_ail.ail_forw->li_ail.ail_back = lip->li_ail.ail_back;
+	lip->li_ail.ail_back->li_ail.ail_forw = lip->li_ail.ail_forw;
+	lip->li_ail.ail_forw = NULL;
+	lip->li_ail.ail_back = NULL;
+
+	xfs_ail_check(base);
+	return lip;
+}
+
+/*
+ * Return a pointer to the first item in the AIL.
+ * If the AIL is empty, then return NULL.
+ */
+STATIC xfs_log_item_t *
+xfs_ail_min(
+	xfs_ail_entry_t	*base)
+/* ARGSUSED */
+{
+	register xfs_log_item_t *forw = base->ail_forw;
+	if (forw == (xfs_log_item_t*)base) {
+		return NULL;
+	}
+	return forw;
+}
+
+/*
+ * Return a pointer to the item which follows
+ * the given item in the AIL.  If the given item
+ * is the last item in the list, then return NULL.
+ */
+STATIC xfs_log_item_t *
+xfs_ail_next(
+	xfs_ail_entry_t	*base,
+	xfs_log_item_t	*lip)
+/* ARGSUSED */
+{
+	if (lip->li_ail.ail_forw == (xfs_log_item_t*)base) {
+		return NULL;
+	}
+	return lip->li_ail.ail_forw;
+
+}
+
+#ifdef XFSDEBUG
+/*
+ * Check that the list is sorted as it should be.
+ */
+STATIC void
+xfs_ail_check(
+	xfs_ail_entry_t *base)
+{
+	xfs_log_item_t	*lip;
+	xfs_log_item_t	*prev_lip;
+
+	lip = base->ail_forw;
+	if (lip == (xfs_log_item_t*)base) {
+		/*
+		 * Make sure the pointers are correct when the list
+		 * is empty.
+		 */
+		ASSERT(base->ail_back == (xfs_log_item_t*)base);
+		return;
+	}
+
+	/*
+	 * Walk the list checking forward and backward pointers,
+	 * lsn ordering, and that every entry has the XFS_LI_IN_AIL
+	 * flag set.
+	 */
+	prev_lip = (xfs_log_item_t*)base;
+	while (lip != (xfs_log_item_t*)base) {
+		if (prev_lip != (xfs_log_item_t*)base) {
+			ASSERT(prev_lip->li_ail.ail_forw == lip);
+			ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
+		}
+		ASSERT(lip->li_ail.ail_back == prev_lip);
+		ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
+		prev_lip = lip;
+		lip = lip->li_ail.ail_forw;
+	}
+	ASSERT(lip == (xfs_log_item_t*)base);
+	ASSERT(base->ail_back == prev_lip);
+}
+#endif /* XFSDEBUG */