Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
| 46 | STATIC void xfs_ail_insert(xfs_ail_entry_t *, xfs_log_item_t *); |
| 47 | STATIC xfs_log_item_t * xfs_ail_delete(xfs_ail_entry_t *, xfs_log_item_t *); |
| 48 | STATIC xfs_log_item_t * xfs_ail_min(xfs_ail_entry_t *); |
| 49 | STATIC xfs_log_item_t * xfs_ail_next(xfs_ail_entry_t *, xfs_log_item_t *); |
| 50 | |
| 51 | #ifdef DEBUG |
| 52 | STATIC 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 | */ |
| 67 | xfs_lsn_t |
| 68 | xfs_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 | */ |
| 96 | xfs_lsn_t |
| 97 | xfs_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 | */ |
| 237 | void |
| 238 | xfs_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 | */ |
| 290 | void |
| 291 | xfs_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 | */ |
| 343 | void |
| 344 | xfs_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 | */ |
| 395 | xfs_log_item_t * |
| 396 | xfs_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 | */ |
| 415 | xfs_log_item_t * |
| 416 | xfs_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 | */ |
| 454 | void |
| 455 | xfs_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 | */ |
| 468 | STATIC void |
| 469 | xfs_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*/ |
| 507 | STATIC xfs_log_item_t * |
| 508 | xfs_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 | */ |
| 526 | STATIC xfs_log_item_t * |
| 527 | xfs_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 | */ |
| 543 | STATIC xfs_log_item_t * |
| 544 | xfs_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 | */ |
| 560 | STATIC void |
| 561 | xfs_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 */ |