2 * Copyright (c) 2000-2002 Silicon Graphics, Inc. All Rights Reserved.
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of version 2 of the GNU General Public License as
6 * published by the Free Software Foundation.
8 * This program is distributed in the hope that it would be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
12 * Further, this software is distributed without any warranty that it is
13 * free of the rightful claim of any third person regarding infringement
14 * or the like. Any license provided herein, whether implied or
15 * otherwise, applies only to this software file. Patent licenses, if
16 * any, provided herein do not apply to combinations of this program with
17 * other software, or any other product whatsoever.
19 * You should have received a copy of the GNU General Public License along
20 * with this program; if not, write the Free Software Foundation, Inc., 59
21 * Temple Place - Suite 330, Boston MA 02111-1307, USA.
23 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
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28 * For further information regarding this notice, see:
30 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
34 #include "xfs_types.h"
37 #include "xfs_trans.h"
40 #include "xfs_dmapi.h"
41 #include "xfs_mount.h"
42 #include "xfs_trans_priv.h"
43 #include "xfs_error.h"
45 STATIC void xfs_ail_insert(xfs_ail_entry_t *, xfs_log_item_t *);
46 STATIC xfs_log_item_t * xfs_ail_delete(xfs_ail_entry_t *, xfs_log_item_t *);
47 STATIC xfs_log_item_t * xfs_ail_min(xfs_ail_entry_t *);
48 STATIC xfs_log_item_t * xfs_ail_next(xfs_ail_entry_t *, xfs_log_item_t *);
51 STATIC void xfs_ail_check(xfs_ail_entry_t *);
53 #define xfs_ail_check(a)
58 * This is called by the log manager code to determine the LSN
59 * of the tail of the log. This is exactly the LSN of the first
60 * item in the AIL. If the AIL is empty, then this function
63 * We need the AIL lock in order to get a coherent read of the
64 * lsn of the last item in the AIL.
75 lip = xfs_ail_min(&(mp->m_ail));
89 * This routine is called to move the tail of the AIL
90 * forward. It does this by trying to flush items in the AIL
91 * whose lsns are below the given threshold_lsn.
93 * The routine returns the lsn of the tail of the log.
98 xfs_lsn_t threshold_lsn)
108 #define XFS_TRANS_PUSH_AIL_RESTARTS 10
111 lip = xfs_trans_first_ail(mp, &gen);
112 if (lip == NULL || XFS_FORCED_SHUTDOWN(mp)) {
114 * Just return if the AIL is empty.
120 XFS_STATS_INC(xs_push_ail);
123 * While the item we are looking at is below the given threshold
124 * try to flush it out. Make sure to limit the number of times
125 * we allow xfs_trans_next_ail() to restart scanning from the
126 * beginning of the list. We'd like not to stop until we've at least
127 * tried to push on everything in the AIL with an LSN less than
128 * the given threshold. However, we may give up before that if
129 * we realize that we've been holding the AIL_LOCK for 'too long',
130 * blocking interrupts. Currently, too long is < 500us roughly.
134 while (((restarts < XFS_TRANS_PUSH_AIL_RESTARTS) &&
135 (XFS_LSN_CMP(lip->li_lsn, threshold_lsn) < 0))) {
137 * If we can lock the item without sleeping, unlock
138 * the AIL lock and flush the item. Then re-grab the
139 * AIL lock so we can look for the next item on the
140 * AIL. Since we unlock the AIL while we flush the
141 * item, the next routine may start over again at the
142 * the beginning of the list if anything has changed.
143 * That is what the generation count is for.
145 * If we can't lock the item, either its holder will flush
146 * it or it is already being flushed or it is being relogged.
147 * In any of these case it is being taken care of and we
148 * can just skip to the next item in the list.
150 lock_result = IOP_TRYLOCK(lip);
151 switch (lock_result) {
152 case XFS_ITEM_SUCCESS:
154 XFS_STATS_INC(xs_push_ail_success);
159 case XFS_ITEM_PUSHBUF:
161 XFS_STATS_INC(xs_push_ail_pushbuf);
166 ASSERT(lip->li_ops->iop_pushbuf);
172 case XFS_ITEM_PINNED:
173 XFS_STATS_INC(xs_push_ail_pinned);
177 case XFS_ITEM_LOCKED:
178 XFS_STATS_INC(xs_push_ail_locked);
181 case XFS_ITEM_FLUSHING:
182 XFS_STATS_INC(xs_push_ail_flushing);
190 lip = xfs_trans_next_ail(mp, lip, &gen, &restarts);
194 if (XFS_FORCED_SHUTDOWN(mp)) {
196 * Just return if we shut down during the last try.
206 * If something we need to push out was pinned, then
207 * push out the log so it will become unpinned and
208 * move forward in the AIL.
211 XFS_STATS_INC(xs_push_ail_flush);
212 xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
216 lip = xfs_ail_min(&(mp->m_ail));
225 } /* xfs_trans_push_ail */
229 * This is to be called when an item is unlocked that may have
230 * been in the AIL. It will wake up the first member of the AIL
231 * wait list if this item's unlocking might allow it to progress.
232 * If the item is in the AIL, then we need to get the AIL lock
233 * while doing our checking so we don't race with someone going
234 * to sleep waiting for this event in xfs_trans_push_ail().
237 xfs_trans_unlocked_item(
241 xfs_log_item_t *min_lip;
244 * If we're forcibly shutting down, we may have
245 * unlocked log items arbitrarily. The last thing
246 * we want to do is to move the tail of the log
247 * over some potentially valid data.
249 if (!(lip->li_flags & XFS_LI_IN_AIL) ||
250 XFS_FORCED_SHUTDOWN(mp)) {
255 * This is the one case where we can call into xfs_ail_min()
256 * without holding the AIL lock because we only care about the
257 * case where we are at the tail of the AIL. If the object isn't
258 * at the tail, it doesn't matter what result we get back. This
259 * is slightly racy because since we were just unlocked, we could
260 * go to sleep between the call to xfs_ail_min and the call to
261 * xfs_log_move_tail, have someone else lock us, commit to us disk,
262 * move us out of the tail of the AIL, and then we wake up. However,
263 * the call to xfs_log_move_tail() doesn't do anything if there's
264 * not enough free space to wake people up so we're safe calling it.
266 min_lip = xfs_ail_min(&mp->m_ail);
269 xfs_log_move_tail(mp, 1);
270 } /* xfs_trans_unlocked_item */
274 * Update the position of the item in the AIL with the new
275 * lsn. If it is not yet in the AIL, add it. Otherwise, move
276 * it to its new position by removing it and re-adding it.
278 * Wakeup anyone with an lsn less than the item's lsn. If the item
279 * we move in the AIL is the minimum one, update the tail lsn in the
282 * Increment the AIL's generation count to indicate that the tree
285 * This function must be called with the AIL lock held. The lock
286 * is dropped before returning, so the caller must pass in the
287 * cookie returned by AIL_LOCK.
290 xfs_trans_update_ail(
296 xfs_ail_entry_t *ailp;
297 xfs_log_item_t *dlip=NULL;
298 xfs_log_item_t *mlip; /* ptr to minimum lip */
301 mlip = xfs_ail_min(ailp);
303 if (lip->li_flags & XFS_LI_IN_AIL) {
304 dlip = xfs_ail_delete(ailp, lip);
307 lip->li_flags |= XFS_LI_IN_AIL;
312 xfs_ail_insert(ailp, lip);
316 mlip = xfs_ail_min(&(mp->m_ail));
318 xfs_log_move_tail(mp, mlip->li_lsn);
324 } /* xfs_trans_update_ail */
327 * Delete the given item from the AIL. It must already be in
330 * Wakeup anyone with an lsn less than item's lsn. If the item
331 * we delete in the AIL is the minimum one, update the tail lsn in the
334 * Clear the IN_AIL flag from the item, reset its lsn to 0, and
335 * bump the AIL's generation count to indicate that the tree
338 * This function must be called with the AIL lock held. The lock
339 * is dropped before returning, so the caller must pass in the
340 * cookie returned by AIL_LOCK.
343 xfs_trans_delete_ail(
348 xfs_ail_entry_t *ailp;
349 xfs_log_item_t *dlip;
350 xfs_log_item_t *mlip;
352 if (lip->li_flags & XFS_LI_IN_AIL) {
354 mlip = xfs_ail_min(ailp);
355 dlip = xfs_ail_delete(ailp, lip);
359 lip->li_flags &= ~XFS_LI_IN_AIL;
364 mlip = xfs_ail_min(&(mp->m_ail));
366 xfs_log_move_tail(mp, (mlip ? mlip->li_lsn : 0));
373 * If the file system is not being shutdown, we are in
374 * serious trouble if we get to this stage.
376 if (XFS_FORCED_SHUTDOWN(mp))
379 xfs_cmn_err(XFS_PTAG_AILDELETE, CE_ALERT, mp,
380 "xfs_trans_delete_ail: attempting to delete a log item that is not in the AIL");
382 xfs_force_shutdown(mp, XFS_CORRUPT_INCORE);
390 * Return the item in the AIL with the smallest lsn.
391 * Return the current tree generation number for use
392 * in calls to xfs_trans_next_ail().
401 lip = xfs_ail_min(&(mp->m_ail));
402 *gen = (int)mp->m_ail_gen;
408 * If the generation count of the tree has not changed since the
409 * caller last took something from the AIL, then return the elmt
410 * in the tree which follows the one given. If the count has changed,
411 * then return the minimum elmt of the AIL and bump the restarts counter
421 xfs_log_item_t *nlip;
423 ASSERT(mp && lip && gen);
424 if (mp->m_ail_gen == *gen) {
425 nlip = xfs_ail_next(&(mp->m_ail), lip);
427 nlip = xfs_ail_min(&(mp->m_ail));
428 *gen = (int)mp->m_ail_gen;
429 if (restarts != NULL) {
430 XFS_STATS_INC(xs_push_ail_restarts);
440 * The active item list (AIL) is a doubly linked list of log
441 * items sorted by ascending lsn. The base of the list is
442 * a forw/back pointer pair embedded in the xfs mount structure.
443 * The base is initialized with both pointers pointing to the
444 * base. This case always needs to be distinguished, because
445 * the base has no lsn to look at. We almost always insert
446 * at the end of the list, so on inserts we search from the
447 * end of the list to find where the new item belongs.
451 * Initialize the doubly linked list to point only to itself.
457 mp->m_ail.ail_forw = (xfs_log_item_t*)&(mp->m_ail);
458 mp->m_ail.ail_back = (xfs_log_item_t*)&(mp->m_ail);
462 * Insert the given log item into the AIL.
463 * We almost always insert at the end of the list, so on inserts
464 * we search from the end of the list to find where the
469 xfs_ail_entry_t *base,
473 xfs_log_item_t *next_lip;
476 * If the list is empty, just insert the item.
478 if (base->ail_back == (xfs_log_item_t*)base) {
479 base->ail_forw = lip;
480 base->ail_back = lip;
481 lip->li_ail.ail_forw = (xfs_log_item_t*)base;
482 lip->li_ail.ail_back = (xfs_log_item_t*)base;
486 next_lip = base->ail_back;
487 while ((next_lip != (xfs_log_item_t*)base) &&
488 (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) > 0)) {
489 next_lip = next_lip->li_ail.ail_back;
491 ASSERT((next_lip == (xfs_log_item_t*)base) ||
492 (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0));
493 lip->li_ail.ail_forw = next_lip->li_ail.ail_forw;
494 lip->li_ail.ail_back = next_lip;
495 next_lip->li_ail.ail_forw = lip;
496 lip->li_ail.ail_forw->li_ail.ail_back = lip;
503 * Delete the given item from the AIL. Return a pointer to the item.
506 STATIC xfs_log_item_t *
508 xfs_ail_entry_t *base,
512 lip->li_ail.ail_forw->li_ail.ail_back = lip->li_ail.ail_back;
513 lip->li_ail.ail_back->li_ail.ail_forw = lip->li_ail.ail_forw;
514 lip->li_ail.ail_forw = NULL;
515 lip->li_ail.ail_back = NULL;
522 * Return a pointer to the first item in the AIL.
523 * If the AIL is empty, then return NULL.
525 STATIC xfs_log_item_t *
527 xfs_ail_entry_t *base)
530 register xfs_log_item_t *forw = base->ail_forw;
531 if (forw == (xfs_log_item_t*)base) {
538 * Return a pointer to the item which follows
539 * the given item in the AIL. If the given item
540 * is the last item in the list, then return NULL.
542 STATIC xfs_log_item_t *
544 xfs_ail_entry_t *base,
548 if (lip->li_ail.ail_forw == (xfs_log_item_t*)base) {
551 return lip->li_ail.ail_forw;
557 * Check that the list is sorted as it should be.
561 xfs_ail_entry_t *base)
564 xfs_log_item_t *prev_lip;
566 lip = base->ail_forw;
567 if (lip == (xfs_log_item_t*)base) {
569 * Make sure the pointers are correct when the list
572 ASSERT(base->ail_back == (xfs_log_item_t*)base);
577 * Walk the list checking forward and backward pointers,
578 * lsn ordering, and that every entry has the XFS_LI_IN_AIL
581 prev_lip = (xfs_log_item_t*)base;
582 while (lip != (xfs_log_item_t*)base) {
583 if (prev_lip != (xfs_log_item_t*)base) {
584 ASSERT(prev_lip->li_ail.ail_forw == lip);
585 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
587 ASSERT(lip->li_ail.ail_back == prev_lip);
588 ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
590 lip = lip->li_ail.ail_forw;
592 ASSERT(lip == (xfs_log_item_t*)base);
593 ASSERT(base->ail_back == prev_lip);