1 /* 2 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc. 3 * All Rights Reserved. 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License as 7 * published by the Free Software Foundation. 8 * 9 * This program is distributed in the hope that it would be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 17 */ 18 #include "xfs.h" 19 #include "xfs_fs.h" 20 #include "xfs_types.h" 21 #include "xfs_log.h" 22 #include "xfs_inum.h" 23 #include "xfs_trans.h" 24 #include "xfs_sb.h" 25 #include "xfs_ag.h" 26 #include "xfs_dmapi.h" 27 #include "xfs_mount.h" 28 #include "xfs_trans_priv.h" 29 #include "xfs_error.h" 30 31 STATIC void xfs_ail_insert(xfs_ail_entry_t *, xfs_log_item_t *); 32 STATIC xfs_log_item_t * xfs_ail_delete(xfs_ail_entry_t *, xfs_log_item_t *); 33 STATIC xfs_log_item_t * xfs_ail_min(xfs_ail_entry_t *); 34 STATIC xfs_log_item_t * xfs_ail_next(xfs_ail_entry_t *, xfs_log_item_t *); 35 36 #ifdef DEBUG 37 STATIC void xfs_ail_check(xfs_ail_entry_t *); 38 #else 39 #define xfs_ail_check(a) 40 #endif /* DEBUG */ 41 42 43 /* 44 * This is called by the log manager code to determine the LSN 45 * of the tail of the log. This is exactly the LSN of the first 46 * item in the AIL. If the AIL is empty, then this function 47 * returns 0. 48 * 49 * We need the AIL lock in order to get a coherent read of the 50 * lsn of the last item in the AIL. 51 */ 52 xfs_lsn_t 53 xfs_trans_tail_ail( 54 xfs_mount_t *mp) 55 { 56 xfs_lsn_t lsn; 57 xfs_log_item_t *lip; 58 SPLDECL(s); 59 60 AIL_LOCK(mp,s); 61 lip = xfs_ail_min(&(mp->m_ail)); 62 if (lip == NULL) { 63 lsn = (xfs_lsn_t)0; 64 } else { 65 lsn = lip->li_lsn; 66 } 67 AIL_UNLOCK(mp, s); 68 69 return lsn; 70 } 71 72 /* 73 * xfs_trans_push_ail 74 * 75 * This routine is called to move the tail of the AIL 76 * forward. It does this by trying to flush items in the AIL 77 * whose lsns are below the given threshold_lsn. 78 * 79 * The routine returns the lsn of the tail of the log. 80 */ 81 xfs_lsn_t 82 xfs_trans_push_ail( 83 xfs_mount_t *mp, 84 xfs_lsn_t threshold_lsn) 85 { 86 xfs_lsn_t lsn; 87 xfs_log_item_t *lip; 88 int gen; 89 int restarts; 90 int lock_result; 91 int flush_log; 92 SPLDECL(s); 93 94 #define XFS_TRANS_PUSH_AIL_RESTARTS 1000 95 96 AIL_LOCK(mp,s); 97 lip = xfs_trans_first_ail(mp, &gen); 98 if (lip == NULL || XFS_FORCED_SHUTDOWN(mp)) { 99 /* 100 * Just return if the AIL is empty. 101 */ 102 AIL_UNLOCK(mp, s); 103 return (xfs_lsn_t)0; 104 } 105 106 XFS_STATS_INC(xs_push_ail); 107 108 /* 109 * While the item we are looking at is below the given threshold 110 * try to flush it out. Make sure to limit the number of times 111 * we allow xfs_trans_next_ail() to restart scanning from the 112 * beginning of the list. We'd like not to stop until we've at least 113 * tried to push on everything in the AIL with an LSN less than 114 * the given threshold. However, we may give up before that if 115 * we realize that we've been holding the AIL_LOCK for 'too long', 116 * blocking interrupts. Currently, too long is < 500us roughly. 117 */ 118 flush_log = 0; 119 restarts = 0; 120 while (((restarts < XFS_TRANS_PUSH_AIL_RESTARTS) && 121 (XFS_LSN_CMP(lip->li_lsn, threshold_lsn) < 0))) { 122 /* 123 * If we can lock the item without sleeping, unlock 124 * the AIL lock and flush the item. Then re-grab the 125 * AIL lock so we can look for the next item on the 126 * AIL. Since we unlock the AIL while we flush the 127 * item, the next routine may start over again at the 128 * the beginning of the list if anything has changed. 129 * That is what the generation count is for. 130 * 131 * If we can't lock the item, either its holder will flush 132 * it or it is already being flushed or it is being relogged. 133 * In any of these case it is being taken care of and we 134 * can just skip to the next item in the list. 135 */ 136 lock_result = IOP_TRYLOCK(lip); 137 switch (lock_result) { 138 case XFS_ITEM_SUCCESS: 139 AIL_UNLOCK(mp, s); 140 XFS_STATS_INC(xs_push_ail_success); 141 IOP_PUSH(lip); 142 AIL_LOCK(mp,s); 143 break; 144 145 case XFS_ITEM_PUSHBUF: 146 AIL_UNLOCK(mp, s); 147 XFS_STATS_INC(xs_push_ail_pushbuf); 148 #ifdef XFSRACEDEBUG 149 delay_for_intr(); 150 delay(300); 151 #endif 152 ASSERT(lip->li_ops->iop_pushbuf); 153 ASSERT(lip); 154 IOP_PUSHBUF(lip); 155 AIL_LOCK(mp,s); 156 break; 157 158 case XFS_ITEM_PINNED: 159 XFS_STATS_INC(xs_push_ail_pinned); 160 flush_log = 1; 161 break; 162 163 case XFS_ITEM_LOCKED: 164 XFS_STATS_INC(xs_push_ail_locked); 165 break; 166 167 case XFS_ITEM_FLUSHING: 168 XFS_STATS_INC(xs_push_ail_flushing); 169 break; 170 171 default: 172 ASSERT(0); 173 break; 174 } 175 176 lip = xfs_trans_next_ail(mp, lip, &gen, &restarts); 177 if (lip == NULL) { 178 break; 179 } 180 if (XFS_FORCED_SHUTDOWN(mp)) { 181 /* 182 * Just return if we shut down during the last try. 183 */ 184 AIL_UNLOCK(mp, s); 185 return (xfs_lsn_t)0; 186 } 187 188 } 189 190 if (flush_log) { 191 /* 192 * If something we need to push out was pinned, then 193 * push out the log so it will become unpinned and 194 * move forward in the AIL. 195 */ 196 AIL_UNLOCK(mp, s); 197 XFS_STATS_INC(xs_push_ail_flush); 198 xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE); 199 AIL_LOCK(mp, s); 200 } 201 202 lip = xfs_ail_min(&(mp->m_ail)); 203 if (lip == NULL) { 204 lsn = (xfs_lsn_t)0; 205 } else { 206 lsn = lip->li_lsn; 207 } 208 209 AIL_UNLOCK(mp, s); 210 return lsn; 211 } /* xfs_trans_push_ail */ 212 213 214 /* 215 * This is to be called when an item is unlocked that may have 216 * been in the AIL. It will wake up the first member of the AIL 217 * wait list if this item's unlocking might allow it to progress. 218 * If the item is in the AIL, then we need to get the AIL lock 219 * while doing our checking so we don't race with someone going 220 * to sleep waiting for this event in xfs_trans_push_ail(). 221 */ 222 void 223 xfs_trans_unlocked_item( 224 xfs_mount_t *mp, 225 xfs_log_item_t *lip) 226 { 227 xfs_log_item_t *min_lip; 228 229 /* 230 * If we're forcibly shutting down, we may have 231 * unlocked log items arbitrarily. The last thing 232 * we want to do is to move the tail of the log 233 * over some potentially valid data. 234 */ 235 if (!(lip->li_flags & XFS_LI_IN_AIL) || 236 XFS_FORCED_SHUTDOWN(mp)) { 237 return; 238 } 239 240 /* 241 * This is the one case where we can call into xfs_ail_min() 242 * without holding the AIL lock because we only care about the 243 * case where we are at the tail of the AIL. If the object isn't 244 * at the tail, it doesn't matter what result we get back. This 245 * is slightly racy because since we were just unlocked, we could 246 * go to sleep between the call to xfs_ail_min and the call to 247 * xfs_log_move_tail, have someone else lock us, commit to us disk, 248 * move us out of the tail of the AIL, and then we wake up. However, 249 * the call to xfs_log_move_tail() doesn't do anything if there's 250 * not enough free space to wake people up so we're safe calling it. 251 */ 252 min_lip = xfs_ail_min(&mp->m_ail); 253 254 if (min_lip == lip) 255 xfs_log_move_tail(mp, 1); 256 } /* xfs_trans_unlocked_item */ 257 258 259 /* 260 * Update the position of the item in the AIL with the new 261 * lsn. If it is not yet in the AIL, add it. Otherwise, move 262 * it to its new position by removing it and re-adding it. 263 * 264 * Wakeup anyone with an lsn less than the item's lsn. If the item 265 * we move in the AIL is the minimum one, update the tail lsn in the 266 * log manager. 267 * 268 * Increment the AIL's generation count to indicate that the tree 269 * has changed. 270 * 271 * This function must be called with the AIL lock held. The lock 272 * is dropped before returning, so the caller must pass in the 273 * cookie returned by AIL_LOCK. 274 */ 275 void 276 xfs_trans_update_ail( 277 xfs_mount_t *mp, 278 xfs_log_item_t *lip, 279 xfs_lsn_t lsn, 280 unsigned long s) __releases(mp->m_ail_lock) 281 { 282 xfs_ail_entry_t *ailp; 283 xfs_log_item_t *dlip=NULL; 284 xfs_log_item_t *mlip; /* ptr to minimum lip */ 285 286 ailp = &(mp->m_ail); 287 mlip = xfs_ail_min(ailp); 288 289 if (lip->li_flags & XFS_LI_IN_AIL) { 290 dlip = xfs_ail_delete(ailp, lip); 291 ASSERT(dlip == lip); 292 } else { 293 lip->li_flags |= XFS_LI_IN_AIL; 294 } 295 296 lip->li_lsn = lsn; 297 298 xfs_ail_insert(ailp, lip); 299 mp->m_ail_gen++; 300 301 if (mlip == dlip) { 302 mlip = xfs_ail_min(&(mp->m_ail)); 303 AIL_UNLOCK(mp, s); 304 xfs_log_move_tail(mp, mlip->li_lsn); 305 } else { 306 AIL_UNLOCK(mp, s); 307 } 308 309 310 } /* xfs_trans_update_ail */ 311 312 /* 313 * Delete the given item from the AIL. It must already be in 314 * the AIL. 315 * 316 * Wakeup anyone with an lsn less than item's lsn. If the item 317 * we delete in the AIL is the minimum one, update the tail lsn in the 318 * log manager. 319 * 320 * Clear the IN_AIL flag from the item, reset its lsn to 0, and 321 * bump the AIL's generation count to indicate that the tree 322 * has changed. 323 * 324 * This function must be called with the AIL lock held. The lock 325 * is dropped before returning, so the caller must pass in the 326 * cookie returned by AIL_LOCK. 327 */ 328 void 329 xfs_trans_delete_ail( 330 xfs_mount_t *mp, 331 xfs_log_item_t *lip, 332 unsigned long s) __releases(mp->m_ail_lock) 333 { 334 xfs_ail_entry_t *ailp; 335 xfs_log_item_t *dlip; 336 xfs_log_item_t *mlip; 337 338 if (lip->li_flags & XFS_LI_IN_AIL) { 339 ailp = &(mp->m_ail); 340 mlip = xfs_ail_min(ailp); 341 dlip = xfs_ail_delete(ailp, lip); 342 ASSERT(dlip == lip); 343 344 345 lip->li_flags &= ~XFS_LI_IN_AIL; 346 lip->li_lsn = 0; 347 mp->m_ail_gen++; 348 349 if (mlip == dlip) { 350 mlip = xfs_ail_min(&(mp->m_ail)); 351 AIL_UNLOCK(mp, s); 352 xfs_log_move_tail(mp, (mlip ? mlip->li_lsn : 0)); 353 } else { 354 AIL_UNLOCK(mp, s); 355 } 356 } 357 else { 358 /* 359 * If the file system is not being shutdown, we are in 360 * serious trouble if we get to this stage. 361 */ 362 if (XFS_FORCED_SHUTDOWN(mp)) 363 AIL_UNLOCK(mp, s); 364 else { 365 xfs_cmn_err(XFS_PTAG_AILDELETE, CE_ALERT, mp, 366 "%s: attempting to delete a log item that is not in the AIL", 367 __FUNCTION__); 368 AIL_UNLOCK(mp, s); 369 xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE); 370 } 371 } 372 } 373 374 375 376 /* 377 * Return the item in the AIL with the smallest lsn. 378 * Return the current tree generation number for use 379 * in calls to xfs_trans_next_ail(). 380 */ 381 xfs_log_item_t * 382 xfs_trans_first_ail( 383 xfs_mount_t *mp, 384 int *gen) 385 { 386 xfs_log_item_t *lip; 387 388 lip = xfs_ail_min(&(mp->m_ail)); 389 *gen = (int)mp->m_ail_gen; 390 391 return (lip); 392 } 393 394 /* 395 * If the generation count of the tree has not changed since the 396 * caller last took something from the AIL, then return the elmt 397 * in the tree which follows the one given. If the count has changed, 398 * then return the minimum elmt of the AIL and bump the restarts counter 399 * if one is given. 400 */ 401 xfs_log_item_t * 402 xfs_trans_next_ail( 403 xfs_mount_t *mp, 404 xfs_log_item_t *lip, 405 int *gen, 406 int *restarts) 407 { 408 xfs_log_item_t *nlip; 409 410 ASSERT(mp && lip && gen); 411 if (mp->m_ail_gen == *gen) { 412 nlip = xfs_ail_next(&(mp->m_ail), lip); 413 } else { 414 nlip = xfs_ail_min(&(mp->m_ail)); 415 *gen = (int)mp->m_ail_gen; 416 if (restarts != NULL) { 417 XFS_STATS_INC(xs_push_ail_restarts); 418 (*restarts)++; 419 } 420 } 421 422 return (nlip); 423 } 424 425 426 /* 427 * The active item list (AIL) is a doubly linked list of log 428 * items sorted by ascending lsn. The base of the list is 429 * a forw/back pointer pair embedded in the xfs mount structure. 430 * The base is initialized with both pointers pointing to the 431 * base. This case always needs to be distinguished, because 432 * the base has no lsn to look at. We almost always insert 433 * at the end of the list, so on inserts we search from the 434 * end of the list to find where the new item belongs. 435 */ 436 437 /* 438 * Initialize the doubly linked list to point only to itself. 439 */ 440 void 441 xfs_trans_ail_init( 442 xfs_mount_t *mp) 443 { 444 mp->m_ail.ail_forw = (xfs_log_item_t*)&(mp->m_ail); 445 mp->m_ail.ail_back = (xfs_log_item_t*)&(mp->m_ail); 446 } 447 448 /* 449 * Insert the given log item into the AIL. 450 * We almost always insert at the end of the list, so on inserts 451 * we search from the end of the list to find where the 452 * new item belongs. 453 */ 454 STATIC void 455 xfs_ail_insert( 456 xfs_ail_entry_t *base, 457 xfs_log_item_t *lip) 458 /* ARGSUSED */ 459 { 460 xfs_log_item_t *next_lip; 461 462 /* 463 * If the list is empty, just insert the item. 464 */ 465 if (base->ail_back == (xfs_log_item_t*)base) { 466 base->ail_forw = lip; 467 base->ail_back = lip; 468 lip->li_ail.ail_forw = (xfs_log_item_t*)base; 469 lip->li_ail.ail_back = (xfs_log_item_t*)base; 470 return; 471 } 472 473 next_lip = base->ail_back; 474 while ((next_lip != (xfs_log_item_t*)base) && 475 (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) > 0)) { 476 next_lip = next_lip->li_ail.ail_back; 477 } 478 ASSERT((next_lip == (xfs_log_item_t*)base) || 479 (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0)); 480 lip->li_ail.ail_forw = next_lip->li_ail.ail_forw; 481 lip->li_ail.ail_back = next_lip; 482 next_lip->li_ail.ail_forw = lip; 483 lip->li_ail.ail_forw->li_ail.ail_back = lip; 484 485 xfs_ail_check(base); 486 return; 487 } 488 489 /* 490 * Delete the given item from the AIL. Return a pointer to the item. 491 */ 492 /*ARGSUSED*/ 493 STATIC xfs_log_item_t * 494 xfs_ail_delete( 495 xfs_ail_entry_t *base, 496 xfs_log_item_t *lip) 497 /* ARGSUSED */ 498 { 499 lip->li_ail.ail_forw->li_ail.ail_back = lip->li_ail.ail_back; 500 lip->li_ail.ail_back->li_ail.ail_forw = lip->li_ail.ail_forw; 501 lip->li_ail.ail_forw = NULL; 502 lip->li_ail.ail_back = NULL; 503 504 xfs_ail_check(base); 505 return lip; 506 } 507 508 /* 509 * Return a pointer to the first item in the AIL. 510 * If the AIL is empty, then return NULL. 511 */ 512 STATIC xfs_log_item_t * 513 xfs_ail_min( 514 xfs_ail_entry_t *base) 515 /* ARGSUSED */ 516 { 517 register xfs_log_item_t *forw = base->ail_forw; 518 if (forw == (xfs_log_item_t*)base) { 519 return NULL; 520 } 521 return forw; 522 } 523 524 /* 525 * Return a pointer to the item which follows 526 * the given item in the AIL. If the given item 527 * is the last item in the list, then return NULL. 528 */ 529 STATIC xfs_log_item_t * 530 xfs_ail_next( 531 xfs_ail_entry_t *base, 532 xfs_log_item_t *lip) 533 /* ARGSUSED */ 534 { 535 if (lip->li_ail.ail_forw == (xfs_log_item_t*)base) { 536 return NULL; 537 } 538 return lip->li_ail.ail_forw; 539 540 } 541 542 #ifdef DEBUG 543 /* 544 * Check that the list is sorted as it should be. 545 */ 546 STATIC void 547 xfs_ail_check( 548 xfs_ail_entry_t *base) 549 { 550 xfs_log_item_t *lip; 551 xfs_log_item_t *prev_lip; 552 553 lip = base->ail_forw; 554 if (lip == (xfs_log_item_t*)base) { 555 /* 556 * Make sure the pointers are correct when the list 557 * is empty. 558 */ 559 ASSERT(base->ail_back == (xfs_log_item_t*)base); 560 return; 561 } 562 563 /* 564 * Walk the list checking forward and backward pointers, 565 * lsn ordering, and that every entry has the XFS_LI_IN_AIL 566 * flag set. 567 */ 568 prev_lip = (xfs_log_item_t*)base; 569 while (lip != (xfs_log_item_t*)base) { 570 if (prev_lip != (xfs_log_item_t*)base) { 571 ASSERT(prev_lip->li_ail.ail_forw == lip); 572 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0); 573 } 574 ASSERT(lip->li_ail.ail_back == prev_lip); 575 ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0); 576 prev_lip = lip; 577 lip = lip->li_ail.ail_forw; 578 } 579 ASSERT(lip == (xfs_log_item_t*)base); 580 ASSERT(base->ail_back == prev_lip); 581 } 582 #endif /* DEBUG */ 583