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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /fs/xfs/xfs_trans_ail.c
Linux-2.6.12-rc2v2.6.12-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!
Diffstat (limited to 'fs/xfs/xfs_trans_ail.c')
-rw-r--r--fs/xfs/xfs_trans_ail.c596
1 files changed, 596 insertions, 0 deletions
diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
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1/*
2 * Copyright (c) 2000-2002 Silicon Graphics, Inc. All Rights Reserved.
3 *
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.
7 *
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.
11 *
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.
18 *
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.
22 *
23 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
24 * Mountain View, CA 94043, or:
25 *
26 * http://www.sgi.com
27 *
28 * For further information regarding this notice, see:
29 *
30 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
31 */
32
33#include "xfs.h"
34#include "xfs_macros.h"
35#include "xfs_types.h"
36#include "xfs_inum.h"
37#include "xfs_log.h"
38#include "xfs_trans.h"
39#include "xfs_sb.h"
40#include "xfs_dir.h"
41#include "xfs_dmapi.h"
42#include "xfs_mount.h"
43#include "xfs_trans_priv.h"
44#include "xfs_error.h"
45
46STATIC void xfs_ail_insert(xfs_ail_entry_t *, xfs_log_item_t *);
47STATIC xfs_log_item_t * xfs_ail_delete(xfs_ail_entry_t *, xfs_log_item_t *);
48STATIC xfs_log_item_t * xfs_ail_min(xfs_ail_entry_t *);
49STATIC xfs_log_item_t * xfs_ail_next(xfs_ail_entry_t *, xfs_log_item_t *);
50
51#ifdef DEBUG
52STATIC void xfs_ail_check(xfs_ail_entry_t *);
53#else
54#define xfs_ail_check(a)
55#endif /* DEBUG */
56
57
58/*
59 * This is called by the log manager code to determine the LSN
60 * of the tail of the log. This is exactly the LSN of the first
61 * item in the AIL. If the AIL is empty, then this function
62 * returns 0.
63 *
64 * We need the AIL lock in order to get a coherent read of the
65 * lsn of the last item in the AIL.
66 */
67xfs_lsn_t
68xfs_trans_tail_ail(
69 xfs_mount_t *mp)
70{
71 xfs_lsn_t lsn;
72 xfs_log_item_t *lip;
73 SPLDECL(s);
74
75 AIL_LOCK(mp,s);
76 lip = xfs_ail_min(&(mp->m_ail));
77 if (lip == NULL) {
78 lsn = (xfs_lsn_t)0;
79 } else {
80 lsn = lip->li_lsn;
81 }
82 AIL_UNLOCK(mp, s);
83
84 return lsn;
85}
86
87/*
88 * xfs_trans_push_ail
89 *
90 * This routine is called to move the tail of the AIL
91 * forward. It does this by trying to flush items in the AIL
92 * whose lsns are below the given threshold_lsn.
93 *
94 * The routine returns the lsn of the tail of the log.
95 */
96xfs_lsn_t
97xfs_trans_push_ail(
98 xfs_mount_t *mp,
99 xfs_lsn_t threshold_lsn)
100{
101 xfs_lsn_t lsn;
102 xfs_log_item_t *lip;
103 int gen;
104 int restarts;
105 int lock_result;
106 int flush_log;
107 SPLDECL(s);
108
109#define XFS_TRANS_PUSH_AIL_RESTARTS 10
110
111 AIL_LOCK(mp,s);
112 lip = xfs_trans_first_ail(mp, &gen);
113 if (lip == NULL || XFS_FORCED_SHUTDOWN(mp)) {
114 /*
115 * Just return if the AIL is empty.
116 */
117 AIL_UNLOCK(mp, s);
118 return (xfs_lsn_t)0;
119 }
120
121 XFS_STATS_INC(xs_push_ail);
122
123 /*
124 * While the item we are looking at is below the given threshold
125 * try to flush it out. Make sure to limit the number of times
126 * we allow xfs_trans_next_ail() to restart scanning from the
127 * beginning of the list. We'd like not to stop until we've at least
128 * tried to push on everything in the AIL with an LSN less than
129 * the given threshold. However, we may give up before that if
130 * we realize that we've been holding the AIL_LOCK for 'too long',
131 * blocking interrupts. Currently, too long is < 500us roughly.
132 */
133 flush_log = 0;
134 restarts = 0;
135 while (((restarts < XFS_TRANS_PUSH_AIL_RESTARTS) &&
136 (XFS_LSN_CMP(lip->li_lsn, threshold_lsn) < 0))) {
137 /*
138 * If we can lock the item without sleeping, unlock
139 * the AIL lock and flush the item. Then re-grab the
140 * AIL lock so we can look for the next item on the
141 * AIL. Since we unlock the AIL while we flush the
142 * item, the next routine may start over again at the
143 * the beginning of the list if anything has changed.
144 * That is what the generation count is for.
145 *
146 * If we can't lock the item, either its holder will flush
147 * it or it is already being flushed or it is being relogged.
148 * In any of these case it is being taken care of and we
149 * can just skip to the next item in the list.
150 */
151 lock_result = IOP_TRYLOCK(lip);
152 switch (lock_result) {
153 case XFS_ITEM_SUCCESS:
154 AIL_UNLOCK(mp, s);
155 XFS_STATS_INC(xs_push_ail_success);
156 IOP_PUSH(lip);
157 AIL_LOCK(mp,s);
158 break;
159
160 case XFS_ITEM_PUSHBUF:
161 AIL_UNLOCK(mp, s);
162 XFS_STATS_INC(xs_push_ail_pushbuf);
163#ifdef XFSRACEDEBUG
164 delay_for_intr();
165 delay(300);
166#endif
167 ASSERT(lip->li_ops->iop_pushbuf);
168 ASSERT(lip);
169 IOP_PUSHBUF(lip);
170 AIL_LOCK(mp,s);
171 break;
172
173 case XFS_ITEM_PINNED:
174 XFS_STATS_INC(xs_push_ail_pinned);
175 flush_log = 1;
176 break;
177
178 case XFS_ITEM_LOCKED:
179 XFS_STATS_INC(xs_push_ail_locked);
180 break;
181
182 case XFS_ITEM_FLUSHING:
183 XFS_STATS_INC(xs_push_ail_flushing);
184 break;
185
186 default:
187 ASSERT(0);
188 break;
189 }
190
191 lip = xfs_trans_next_ail(mp, lip, &gen, &restarts);
192 if (lip == NULL) {
193 break;
194 }
195 if (XFS_FORCED_SHUTDOWN(mp)) {
196 /*
197 * Just return if we shut down during the last try.
198 */
199 AIL_UNLOCK(mp, s);
200 return (xfs_lsn_t)0;
201 }
202
203 }
204
205 if (flush_log) {
206 /*
207 * If something we need to push out was pinned, then
208 * push out the log so it will become unpinned and
209 * move forward in the AIL.
210 */
211 AIL_UNLOCK(mp, s);
212 XFS_STATS_INC(xs_push_ail_flush);
213 xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
214 AIL_LOCK(mp, s);
215 }
216
217 lip = xfs_ail_min(&(mp->m_ail));
218 if (lip == NULL) {
219 lsn = (xfs_lsn_t)0;
220 } else {
221 lsn = lip->li_lsn;
222 }
223
224 AIL_UNLOCK(mp, s);
225 return lsn;
226} /* xfs_trans_push_ail */
227
228
229/*
230 * This is to be called when an item is unlocked that may have
231 * been in the AIL. It will wake up the first member of the AIL
232 * wait list if this item's unlocking might allow it to progress.
233 * If the item is in the AIL, then we need to get the AIL lock
234 * while doing our checking so we don't race with someone going
235 * to sleep waiting for this event in xfs_trans_push_ail().
236 */
237void
238xfs_trans_unlocked_item(
239 xfs_mount_t *mp,
240 xfs_log_item_t *lip)
241{
242 xfs_log_item_t *min_lip;
243
244 /*
245 * If we're forcibly shutting down, we may have
246 * unlocked log items arbitrarily. The last thing
247 * we want to do is to move the tail of the log
248 * over some potentially valid data.
249 */
250 if (!(lip->li_flags & XFS_LI_IN_AIL) ||
251 XFS_FORCED_SHUTDOWN(mp)) {
252 return;
253 }
254
255 /*
256 * This is the one case where we can call into xfs_ail_min()
257 * without holding the AIL lock because we only care about the
258 * case where we are at the tail of the AIL. If the object isn't
259 * at the tail, it doesn't matter what result we get back. This
260 * is slightly racy because since we were just unlocked, we could
261 * go to sleep between the call to xfs_ail_min and the call to
262 * xfs_log_move_tail, have someone else lock us, commit to us disk,
263 * move us out of the tail of the AIL, and then we wake up. However,
264 * the call to xfs_log_move_tail() doesn't do anything if there's
265 * not enough free space to wake people up so we're safe calling it.
266 */
267 min_lip = xfs_ail_min(&mp->m_ail);
268
269 if (min_lip == lip)
270 xfs_log_move_tail(mp, 1);
271} /* xfs_trans_unlocked_item */
272
273
274/*
275 * Update the position of the item in the AIL with the new
276 * lsn. If it is not yet in the AIL, add it. Otherwise, move
277 * it to its new position by removing it and re-adding it.
278 *
279 * Wakeup anyone with an lsn less than the item's lsn. If the item
280 * we move in the AIL is the minimum one, update the tail lsn in the
281 * log manager.
282 *
283 * Increment the AIL's generation count to indicate that the tree
284 * has changed.
285 *
286 * This function must be called with the AIL lock held. The lock
287 * is dropped before returning, so the caller must pass in the
288 * cookie returned by AIL_LOCK.
289 */
290void
291xfs_trans_update_ail(
292 xfs_mount_t *mp,
293 xfs_log_item_t *lip,
294 xfs_lsn_t lsn,
295 unsigned long s)
296{
297 xfs_ail_entry_t *ailp;
298 xfs_log_item_t *dlip=NULL;
299 xfs_log_item_t *mlip; /* ptr to minimum lip */
300
301 ailp = &(mp->m_ail);
302 mlip = xfs_ail_min(ailp);
303
304 if (lip->li_flags & XFS_LI_IN_AIL) {
305 dlip = xfs_ail_delete(ailp, lip);
306 ASSERT(dlip == lip);
307 } else {
308 lip->li_flags |= XFS_LI_IN_AIL;
309 }
310
311 lip->li_lsn = lsn;
312
313 xfs_ail_insert(ailp, lip);
314 mp->m_ail_gen++;
315
316 if (mlip == dlip) {
317 mlip = xfs_ail_min(&(mp->m_ail));
318 AIL_UNLOCK(mp, s);
319 xfs_log_move_tail(mp, mlip->li_lsn);
320 } else {
321 AIL_UNLOCK(mp, s);
322 }
323
324
325} /* xfs_trans_update_ail */
326
327/*
328 * Delete the given item from the AIL. It must already be in
329 * the AIL.
330 *
331 * Wakeup anyone with an lsn less than item's lsn. If the item
332 * we delete in the AIL is the minimum one, update the tail lsn in the
333 * log manager.
334 *
335 * Clear the IN_AIL flag from the item, reset its lsn to 0, and
336 * bump the AIL's generation count to indicate that the tree
337 * has changed.
338 *
339 * This function must be called with the AIL lock held. The lock
340 * is dropped before returning, so the caller must pass in the
341 * cookie returned by AIL_LOCK.
342 */
343void
344xfs_trans_delete_ail(
345 xfs_mount_t *mp,
346 xfs_log_item_t *lip,
347 unsigned long s)
348{
349 xfs_ail_entry_t *ailp;
350 xfs_log_item_t *dlip;
351 xfs_log_item_t *mlip;
352
353 if (lip->li_flags & XFS_LI_IN_AIL) {
354 ailp = &(mp->m_ail);
355 mlip = xfs_ail_min(ailp);
356 dlip = xfs_ail_delete(ailp, lip);
357 ASSERT(dlip == lip);
358
359
360 lip->li_flags &= ~XFS_LI_IN_AIL;
361 lip->li_lsn = 0;
362 mp->m_ail_gen++;
363
364 if (mlip == dlip) {
365 mlip = xfs_ail_min(&(mp->m_ail));
366 AIL_UNLOCK(mp, s);
367 xfs_log_move_tail(mp, (mlip ? mlip->li_lsn : 0));
368 } else {
369 AIL_UNLOCK(mp, s);
370 }
371 }
372 else {
373 /*
374 * If the file system is not being shutdown, we are in
375 * serious trouble if we get to this stage.
376 */
377 if (XFS_FORCED_SHUTDOWN(mp))
378 AIL_UNLOCK(mp, s);
379 else {
380 xfs_cmn_err(XFS_PTAG_AILDELETE, CE_ALERT, mp,
381 "xfs_trans_delete_ail: attempting to delete a log item that is not in the AIL");
382 xfs_force_shutdown(mp, XFS_CORRUPT_INCORE);
383 AIL_UNLOCK(mp, s);
384 }
385 }
386}
387
388
389
390/*
391 * Return the item in the AIL with the smallest lsn.
392 * Return the current tree generation number for use
393 * in calls to xfs_trans_next_ail().
394 */
395xfs_log_item_t *
396xfs_trans_first_ail(
397 xfs_mount_t *mp,
398 int *gen)
399{
400 xfs_log_item_t *lip;
401
402 lip = xfs_ail_min(&(mp->m_ail));
403 *gen = (int)mp->m_ail_gen;
404
405 return (lip);
406}
407
408/*
409 * If the generation count of the tree has not changed since the
410 * caller last took something from the AIL, then return the elmt
411 * in the tree which follows the one given. If the count has changed,
412 * then return the minimum elmt of the AIL and bump the restarts counter
413 * if one is given.
414 */
415xfs_log_item_t *
416xfs_trans_next_ail(
417 xfs_mount_t *mp,
418 xfs_log_item_t *lip,
419 int *gen,
420 int *restarts)
421{
422 xfs_log_item_t *nlip;
423
424 ASSERT(mp && lip && gen);
425 if (mp->m_ail_gen == *gen) {
426 nlip = xfs_ail_next(&(mp->m_ail), lip);
427 } else {
428 nlip = xfs_ail_min(&(mp->m_ail));
429 *gen = (int)mp->m_ail_gen;
430 if (restarts != NULL) {
431 XFS_STATS_INC(xs_push_ail_restarts);
432 (*restarts)++;
433 }
434 }
435
436 return (nlip);
437}
438
439
440/*
441 * The active item list (AIL) is a doubly linked list of log
442 * items sorted by ascending lsn. The base of the list is
443 * a forw/back pointer pair embedded in the xfs mount structure.
444 * The base is initialized with both pointers pointing to the
445 * base. This case always needs to be distinguished, because
446 * the base has no lsn to look at. We almost always insert
447 * at the end of the list, so on inserts we search from the
448 * end of the list to find where the new item belongs.
449 */
450
451/*
452 * Initialize the doubly linked list to point only to itself.
453 */
454void
455xfs_trans_ail_init(
456 xfs_mount_t *mp)
457{
458 mp->m_ail.ail_forw = (xfs_log_item_t*)&(mp->m_ail);
459 mp->m_ail.ail_back = (xfs_log_item_t*)&(mp->m_ail);
460}
461
462/*
463 * Insert the given log item into the AIL.
464 * We almost always insert at the end of the list, so on inserts
465 * we search from the end of the list to find where the
466 * new item belongs.
467 */
468STATIC void
469xfs_ail_insert(
470 xfs_ail_entry_t *base,
471 xfs_log_item_t *lip)
472/* ARGSUSED */
473{
474 xfs_log_item_t *next_lip;
475
476 /*
477 * If the list is empty, just insert the item.
478 */
479 if (base->ail_back == (xfs_log_item_t*)base) {
480 base->ail_forw = lip;
481 base->ail_back = lip;
482 lip->li_ail.ail_forw = (xfs_log_item_t*)base;
483 lip->li_ail.ail_back = (xfs_log_item_t*)base;
484 return;
485 }
486
487 next_lip = base->ail_back;
488 while ((next_lip != (xfs_log_item_t*)base) &&
489 (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) > 0)) {
490 next_lip = next_lip->li_ail.ail_back;
491 }
492 ASSERT((next_lip == (xfs_log_item_t*)base) ||
493 (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0));
494 lip->li_ail.ail_forw = next_lip->li_ail.ail_forw;
495 lip->li_ail.ail_back = next_lip;
496 next_lip->li_ail.ail_forw = lip;
497 lip->li_ail.ail_forw->li_ail.ail_back = lip;
498
499 xfs_ail_check(base);
500 return;
501}
502
503/*
504 * Delete the given item from the AIL. Return a pointer to the item.
505 */
506/*ARGSUSED*/
507STATIC xfs_log_item_t *
508xfs_ail_delete(
509 xfs_ail_entry_t *base,
510 xfs_log_item_t *lip)
511/* ARGSUSED */
512{
513 lip->li_ail.ail_forw->li_ail.ail_back = lip->li_ail.ail_back;
514 lip->li_ail.ail_back->li_ail.ail_forw = lip->li_ail.ail_forw;
515 lip->li_ail.ail_forw = NULL;
516 lip->li_ail.ail_back = NULL;
517
518 xfs_ail_check(base);
519 return lip;
520}
521
522/*
523 * Return a pointer to the first item in the AIL.
524 * If the AIL is empty, then return NULL.
525 */
526STATIC xfs_log_item_t *
527xfs_ail_min(
528 xfs_ail_entry_t *base)
529/* ARGSUSED */
530{
531 register xfs_log_item_t *forw = base->ail_forw;
532 if (forw == (xfs_log_item_t*)base) {
533 return NULL;
534 }
535 return forw;
536}
537
538/*
539 * Return a pointer to the item which follows
540 * the given item in the AIL. If the given item
541 * is the last item in the list, then return NULL.
542 */
543STATIC xfs_log_item_t *
544xfs_ail_next(
545 xfs_ail_entry_t *base,
546 xfs_log_item_t *lip)
547/* ARGSUSED */
548{
549 if (lip->li_ail.ail_forw == (xfs_log_item_t*)base) {
550 return NULL;
551 }
552 return lip->li_ail.ail_forw;
553
554}
555
556#ifdef DEBUG
557/*
558 * Check that the list is sorted as it should be.
559 */
560STATIC void
561xfs_ail_check(
562 xfs_ail_entry_t *base)
563{
564 xfs_log_item_t *lip;
565 xfs_log_item_t *prev_lip;
566
567 lip = base->ail_forw;
568 if (lip == (xfs_log_item_t*)base) {
569 /*
570 * Make sure the pointers are correct when the list
571 * is empty.
572 */
573 ASSERT(base->ail_back == (xfs_log_item_t*)base);
574 return;
575 }
576
577 /*
578 * Walk the list checking forward and backward pointers,
579 * lsn ordering, and that every entry has the XFS_LI_IN_AIL
580 * flag set.
581 */
582 prev_lip = (xfs_log_item_t*)base;
583 while (lip != (xfs_log_item_t*)base) {
584 if (prev_lip != (xfs_log_item_t*)base) {
585 ASSERT(prev_lip->li_ail.ail_forw == lip);
586 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
587 }
588 ASSERT(lip->li_ail.ail_back == prev_lip);
589 ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
590 prev_lip = lip;
591 lip = lip->li_ail.ail_forw;
592 }
593 ASSERT(lip == (xfs_log_item_t*)base);
594 ASSERT(base->ail_back == prev_lip);
595}
596#endif /* DEBUG */