| 1 | /* |
| 2 | * linux/fs/jbd2/checkpoint.c |
| 3 | * |
| 4 | * Written by Stephen C. Tweedie <sct@redhat.com>, 1999 |
| 5 | * |
| 6 | * Copyright 1999 Red Hat Software --- All Rights Reserved |
| 7 | * |
| 8 | * This file is part of the Linux kernel and is made available under |
| 9 | * the terms of the GNU General Public License, version 2, or at your |
| 10 | * option, any later version, incorporated herein by reference. |
| 11 | * |
| 12 | * Checkpoint routines for the generic filesystem journaling code. |
| 13 | * Part of the ext2fs journaling system. |
| 14 | * |
| 15 | * Checkpointing is the process of ensuring that a section of the log is |
| 16 | * committed fully to disk, so that that portion of the log can be |
| 17 | * reused. |
| 18 | */ |
| 19 | |
| 20 | #include <linux/time.h> |
| 21 | #include <linux/fs.h> |
| 22 | #include <linux/jbd2.h> |
| 23 | #include <linux/errno.h> |
| 24 | #include <linux/slab.h> |
| 25 | #include <linux/blkdev.h> |
| 26 | #include <trace/events/jbd2.h> |
| 27 | |
| 28 | /* |
| 29 | * Unlink a buffer from a transaction checkpoint list. |
| 30 | * |
| 31 | * Called with j_list_lock held. |
| 32 | */ |
| 33 | static inline void __buffer_unlink_first(struct journal_head *jh) |
| 34 | { |
| 35 | transaction_t *transaction = jh->b_cp_transaction; |
| 36 | |
| 37 | jh->b_cpnext->b_cpprev = jh->b_cpprev; |
| 38 | jh->b_cpprev->b_cpnext = jh->b_cpnext; |
| 39 | if (transaction->t_checkpoint_list == jh) { |
| 40 | transaction->t_checkpoint_list = jh->b_cpnext; |
| 41 | if (transaction->t_checkpoint_list == jh) |
| 42 | transaction->t_checkpoint_list = NULL; |
| 43 | } |
| 44 | } |
| 45 | |
| 46 | /* |
| 47 | * Unlink a buffer from a transaction checkpoint(io) list. |
| 48 | * |
| 49 | * Called with j_list_lock held. |
| 50 | */ |
| 51 | static inline void __buffer_unlink(struct journal_head *jh) |
| 52 | { |
| 53 | transaction_t *transaction = jh->b_cp_transaction; |
| 54 | |
| 55 | __buffer_unlink_first(jh); |
| 56 | if (transaction->t_checkpoint_io_list == jh) { |
| 57 | transaction->t_checkpoint_io_list = jh->b_cpnext; |
| 58 | if (transaction->t_checkpoint_io_list == jh) |
| 59 | transaction->t_checkpoint_io_list = NULL; |
| 60 | } |
| 61 | } |
| 62 | |
| 63 | /* |
| 64 | * Move a buffer from the checkpoint list to the checkpoint io list |
| 65 | * |
| 66 | * Called with j_list_lock held |
| 67 | */ |
| 68 | static inline void __buffer_relink_io(struct journal_head *jh) |
| 69 | { |
| 70 | transaction_t *transaction = jh->b_cp_transaction; |
| 71 | |
| 72 | __buffer_unlink_first(jh); |
| 73 | |
| 74 | if (!transaction->t_checkpoint_io_list) { |
| 75 | jh->b_cpnext = jh->b_cpprev = jh; |
| 76 | } else { |
| 77 | jh->b_cpnext = transaction->t_checkpoint_io_list; |
| 78 | jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev; |
| 79 | jh->b_cpprev->b_cpnext = jh; |
| 80 | jh->b_cpnext->b_cpprev = jh; |
| 81 | } |
| 82 | transaction->t_checkpoint_io_list = jh; |
| 83 | } |
| 84 | |
| 85 | /* |
| 86 | * Try to release a checkpointed buffer from its transaction. |
| 87 | * Returns 1 if we released it and 2 if we also released the |
| 88 | * whole transaction. |
| 89 | * |
| 90 | * Requires j_list_lock |
| 91 | */ |
| 92 | static int __try_to_free_cp_buf(struct journal_head *jh) |
| 93 | { |
| 94 | int ret = 0; |
| 95 | struct buffer_head *bh = jh2bh(jh); |
| 96 | |
| 97 | if (jh->b_transaction == NULL && !buffer_locked(bh) && |
| 98 | !buffer_dirty(bh) && !buffer_write_io_error(bh)) { |
| 99 | /* |
| 100 | * Get our reference so that bh cannot be freed before |
| 101 | * we unlock it |
| 102 | */ |
| 103 | get_bh(bh); |
| 104 | JBUFFER_TRACE(jh, "remove from checkpoint list"); |
| 105 | ret = __jbd2_journal_remove_checkpoint(jh) + 1; |
| 106 | BUFFER_TRACE(bh, "release"); |
| 107 | __brelse(bh); |
| 108 | } |
| 109 | return ret; |
| 110 | } |
| 111 | |
| 112 | /* |
| 113 | * __jbd2_log_wait_for_space: wait until there is space in the journal. |
| 114 | * |
| 115 | * Called under j-state_lock *only*. It will be unlocked if we have to wait |
| 116 | * for a checkpoint to free up some space in the log. |
| 117 | */ |
| 118 | void __jbd2_log_wait_for_space(journal_t *journal) |
| 119 | { |
| 120 | int nblocks, space_left; |
| 121 | /* assert_spin_locked(&journal->j_state_lock); */ |
| 122 | |
| 123 | nblocks = jbd_space_needed(journal); |
| 124 | while (__jbd2_log_space_left(journal) < nblocks) { |
| 125 | if (journal->j_flags & JBD2_ABORT) |
| 126 | return; |
| 127 | write_unlock(&journal->j_state_lock); |
| 128 | mutex_lock(&journal->j_checkpoint_mutex); |
| 129 | |
| 130 | /* |
| 131 | * Test again, another process may have checkpointed while we |
| 132 | * were waiting for the checkpoint lock. If there are no |
| 133 | * transactions ready to be checkpointed, try to recover |
| 134 | * journal space by calling cleanup_journal_tail(), and if |
| 135 | * that doesn't work, by waiting for the currently committing |
| 136 | * transaction to complete. If there is absolutely no way |
| 137 | * to make progress, this is either a BUG or corrupted |
| 138 | * filesystem, so abort the journal and leave a stack |
| 139 | * trace for forensic evidence. |
| 140 | */ |
| 141 | write_lock(&journal->j_state_lock); |
| 142 | spin_lock(&journal->j_list_lock); |
| 143 | nblocks = jbd_space_needed(journal); |
| 144 | space_left = __jbd2_log_space_left(journal); |
| 145 | if (space_left < nblocks) { |
| 146 | int chkpt = journal->j_checkpoint_transactions != NULL; |
| 147 | tid_t tid = 0; |
| 148 | |
| 149 | if (journal->j_committing_transaction) |
| 150 | tid = journal->j_committing_transaction->t_tid; |
| 151 | spin_unlock(&journal->j_list_lock); |
| 152 | write_unlock(&journal->j_state_lock); |
| 153 | if (chkpt) { |
| 154 | jbd2_log_do_checkpoint(journal); |
| 155 | } else if (jbd2_cleanup_journal_tail(journal) == 0) { |
| 156 | /* We were able to recover space; yay! */ |
| 157 | ; |
| 158 | } else if (tid) { |
| 159 | jbd2_log_wait_commit(journal, tid); |
| 160 | } else { |
| 161 | printk(KERN_ERR "%s: needed %d blocks and " |
| 162 | "only had %d space available\n", |
| 163 | __func__, nblocks, space_left); |
| 164 | printk(KERN_ERR "%s: no way to get more " |
| 165 | "journal space in %s\n", __func__, |
| 166 | journal->j_devname); |
| 167 | WARN_ON(1); |
| 168 | jbd2_journal_abort(journal, 0); |
| 169 | } |
| 170 | write_lock(&journal->j_state_lock); |
| 171 | } else { |
| 172 | spin_unlock(&journal->j_list_lock); |
| 173 | } |
| 174 | mutex_unlock(&journal->j_checkpoint_mutex); |
| 175 | } |
| 176 | } |
| 177 | |
| 178 | /* |
| 179 | * Clean up transaction's list of buffers submitted for io. |
| 180 | * We wait for any pending IO to complete and remove any clean |
| 181 | * buffers. Note that we take the buffers in the opposite ordering |
| 182 | * from the one in which they were submitted for IO. |
| 183 | * |
| 184 | * Return 0 on success, and return <0 if some buffers have failed |
| 185 | * to be written out. |
| 186 | * |
| 187 | * Called with j_list_lock held. |
| 188 | */ |
| 189 | static int __wait_cp_io(journal_t *journal, transaction_t *transaction) |
| 190 | { |
| 191 | struct journal_head *jh; |
| 192 | struct buffer_head *bh; |
| 193 | tid_t this_tid; |
| 194 | int released = 0; |
| 195 | int ret = 0; |
| 196 | |
| 197 | this_tid = transaction->t_tid; |
| 198 | restart: |
| 199 | /* Did somebody clean up the transaction in the meanwhile? */ |
| 200 | if (journal->j_checkpoint_transactions != transaction || |
| 201 | transaction->t_tid != this_tid) |
| 202 | return ret; |
| 203 | while (!released && transaction->t_checkpoint_io_list) { |
| 204 | jh = transaction->t_checkpoint_io_list; |
| 205 | bh = jh2bh(jh); |
| 206 | get_bh(bh); |
| 207 | if (buffer_locked(bh)) { |
| 208 | spin_unlock(&journal->j_list_lock); |
| 209 | wait_on_buffer(bh); |
| 210 | /* the journal_head may have gone by now */ |
| 211 | BUFFER_TRACE(bh, "brelse"); |
| 212 | __brelse(bh); |
| 213 | spin_lock(&journal->j_list_lock); |
| 214 | goto restart; |
| 215 | } |
| 216 | if (unlikely(buffer_write_io_error(bh))) |
| 217 | ret = -EIO; |
| 218 | |
| 219 | /* |
| 220 | * Now in whatever state the buffer currently is, we know that |
| 221 | * it has been written out and so we can drop it from the list |
| 222 | */ |
| 223 | released = __jbd2_journal_remove_checkpoint(jh); |
| 224 | __brelse(bh); |
| 225 | } |
| 226 | |
| 227 | return ret; |
| 228 | } |
| 229 | |
| 230 | static void |
| 231 | __flush_batch(journal_t *journal, int *batch_count) |
| 232 | { |
| 233 | int i; |
| 234 | struct blk_plug plug; |
| 235 | |
| 236 | blk_start_plug(&plug); |
| 237 | for (i = 0; i < *batch_count; i++) |
| 238 | write_dirty_buffer(journal->j_chkpt_bhs[i], WRITE_SYNC); |
| 239 | blk_finish_plug(&plug); |
| 240 | |
| 241 | for (i = 0; i < *batch_count; i++) { |
| 242 | struct buffer_head *bh = journal->j_chkpt_bhs[i]; |
| 243 | BUFFER_TRACE(bh, "brelse"); |
| 244 | __brelse(bh); |
| 245 | } |
| 246 | *batch_count = 0; |
| 247 | } |
| 248 | |
| 249 | /* |
| 250 | * Try to flush one buffer from the checkpoint list to disk. |
| 251 | * |
| 252 | * Return 1 if something happened which requires us to abort the current |
| 253 | * scan of the checkpoint list. Return <0 if the buffer has failed to |
| 254 | * be written out. |
| 255 | * |
| 256 | * Called with j_list_lock held and drops it if 1 is returned |
| 257 | */ |
| 258 | static int __process_buffer(journal_t *journal, struct journal_head *jh, |
| 259 | int *batch_count, transaction_t *transaction) |
| 260 | { |
| 261 | struct buffer_head *bh = jh2bh(jh); |
| 262 | int ret = 0; |
| 263 | |
| 264 | if (buffer_locked(bh)) { |
| 265 | get_bh(bh); |
| 266 | spin_unlock(&journal->j_list_lock); |
| 267 | wait_on_buffer(bh); |
| 268 | /* the journal_head may have gone by now */ |
| 269 | BUFFER_TRACE(bh, "brelse"); |
| 270 | __brelse(bh); |
| 271 | ret = 1; |
| 272 | } else if (jh->b_transaction != NULL) { |
| 273 | transaction_t *t = jh->b_transaction; |
| 274 | tid_t tid = t->t_tid; |
| 275 | |
| 276 | transaction->t_chp_stats.cs_forced_to_close++; |
| 277 | spin_unlock(&journal->j_list_lock); |
| 278 | if (unlikely(journal->j_flags & JBD2_UNMOUNT)) |
| 279 | /* |
| 280 | * The journal thread is dead; so starting and |
| 281 | * waiting for a commit to finish will cause |
| 282 | * us to wait for a _very_ long time. |
| 283 | */ |
| 284 | printk(KERN_ERR "JBD2: %s: " |
| 285 | "Waiting for Godot: block %llu\n", |
| 286 | journal->j_devname, |
| 287 | (unsigned long long) bh->b_blocknr); |
| 288 | jbd2_log_start_commit(journal, tid); |
| 289 | jbd2_log_wait_commit(journal, tid); |
| 290 | ret = 1; |
| 291 | } else if (!buffer_dirty(bh)) { |
| 292 | ret = 1; |
| 293 | if (unlikely(buffer_write_io_error(bh))) |
| 294 | ret = -EIO; |
| 295 | get_bh(bh); |
| 296 | BUFFER_TRACE(bh, "remove from checkpoint"); |
| 297 | __jbd2_journal_remove_checkpoint(jh); |
| 298 | spin_unlock(&journal->j_list_lock); |
| 299 | __brelse(bh); |
| 300 | } else { |
| 301 | /* |
| 302 | * Important: we are about to write the buffer, and |
| 303 | * possibly block, while still holding the journal lock. |
| 304 | * We cannot afford to let the transaction logic start |
| 305 | * messing around with this buffer before we write it to |
| 306 | * disk, as that would break recoverability. |
| 307 | */ |
| 308 | BUFFER_TRACE(bh, "queue"); |
| 309 | get_bh(bh); |
| 310 | J_ASSERT_BH(bh, !buffer_jwrite(bh)); |
| 311 | journal->j_chkpt_bhs[*batch_count] = bh; |
| 312 | __buffer_relink_io(jh); |
| 313 | transaction->t_chp_stats.cs_written++; |
| 314 | (*batch_count)++; |
| 315 | if (*batch_count == JBD2_NR_BATCH) { |
| 316 | spin_unlock(&journal->j_list_lock); |
| 317 | __flush_batch(journal, batch_count); |
| 318 | ret = 1; |
| 319 | } |
| 320 | } |
| 321 | return ret; |
| 322 | } |
| 323 | |
| 324 | /* |
| 325 | * Perform an actual checkpoint. We take the first transaction on the |
| 326 | * list of transactions to be checkpointed and send all its buffers |
| 327 | * to disk. We submit larger chunks of data at once. |
| 328 | * |
| 329 | * The journal should be locked before calling this function. |
| 330 | * Called with j_checkpoint_mutex held. |
| 331 | */ |
| 332 | int jbd2_log_do_checkpoint(journal_t *journal) |
| 333 | { |
| 334 | transaction_t *transaction; |
| 335 | tid_t this_tid; |
| 336 | int result; |
| 337 | |
| 338 | jbd_debug(1, "Start checkpoint\n"); |
| 339 | |
| 340 | /* |
| 341 | * First thing: if there are any transactions in the log which |
| 342 | * don't need checkpointing, just eliminate them from the |
| 343 | * journal straight away. |
| 344 | */ |
| 345 | result = jbd2_cleanup_journal_tail(journal); |
| 346 | trace_jbd2_checkpoint(journal, result); |
| 347 | jbd_debug(1, "cleanup_journal_tail returned %d\n", result); |
| 348 | if (result <= 0) |
| 349 | return result; |
| 350 | |
| 351 | /* |
| 352 | * OK, we need to start writing disk blocks. Take one transaction |
| 353 | * and write it. |
| 354 | */ |
| 355 | result = 0; |
| 356 | spin_lock(&journal->j_list_lock); |
| 357 | if (!journal->j_checkpoint_transactions) |
| 358 | goto out; |
| 359 | transaction = journal->j_checkpoint_transactions; |
| 360 | if (transaction->t_chp_stats.cs_chp_time == 0) |
| 361 | transaction->t_chp_stats.cs_chp_time = jiffies; |
| 362 | this_tid = transaction->t_tid; |
| 363 | restart: |
| 364 | /* |
| 365 | * If someone cleaned up this transaction while we slept, we're |
| 366 | * done (maybe it's a new transaction, but it fell at the same |
| 367 | * address). |
| 368 | */ |
| 369 | if (journal->j_checkpoint_transactions == transaction && |
| 370 | transaction->t_tid == this_tid) { |
| 371 | int batch_count = 0; |
| 372 | struct journal_head *jh; |
| 373 | int retry = 0, err; |
| 374 | |
| 375 | while (!retry && transaction->t_checkpoint_list) { |
| 376 | jh = transaction->t_checkpoint_list; |
| 377 | retry = __process_buffer(journal, jh, &batch_count, |
| 378 | transaction); |
| 379 | if (retry < 0 && !result) |
| 380 | result = retry; |
| 381 | if (!retry && (need_resched() || |
| 382 | spin_needbreak(&journal->j_list_lock))) { |
| 383 | spin_unlock(&journal->j_list_lock); |
| 384 | retry = 1; |
| 385 | break; |
| 386 | } |
| 387 | } |
| 388 | |
| 389 | if (batch_count) { |
| 390 | if (!retry) { |
| 391 | spin_unlock(&journal->j_list_lock); |
| 392 | retry = 1; |
| 393 | } |
| 394 | __flush_batch(journal, &batch_count); |
| 395 | } |
| 396 | |
| 397 | if (retry) { |
| 398 | spin_lock(&journal->j_list_lock); |
| 399 | goto restart; |
| 400 | } |
| 401 | /* |
| 402 | * Now we have cleaned up the first transaction's checkpoint |
| 403 | * list. Let's clean up the second one |
| 404 | */ |
| 405 | err = __wait_cp_io(journal, transaction); |
| 406 | if (!result) |
| 407 | result = err; |
| 408 | } |
| 409 | out: |
| 410 | spin_unlock(&journal->j_list_lock); |
| 411 | if (result < 0) |
| 412 | jbd2_journal_abort(journal, result); |
| 413 | else |
| 414 | result = jbd2_cleanup_journal_tail(journal); |
| 415 | |
| 416 | return (result < 0) ? result : 0; |
| 417 | } |
| 418 | |
| 419 | /* |
| 420 | * Check the list of checkpoint transactions for the journal to see if |
| 421 | * we have already got rid of any since the last update of the log tail |
| 422 | * in the journal superblock. If so, we can instantly roll the |
| 423 | * superblock forward to remove those transactions from the log. |
| 424 | * |
| 425 | * Return <0 on error, 0 on success, 1 if there was nothing to clean up. |
| 426 | * |
| 427 | * Called with the journal lock held. |
| 428 | * |
| 429 | * This is the only part of the journaling code which really needs to be |
| 430 | * aware of transaction aborts. Checkpointing involves writing to the |
| 431 | * main filesystem area rather than to the journal, so it can proceed |
| 432 | * even in abort state, but we must not update the super block if |
| 433 | * checkpointing may have failed. Otherwise, we would lose some metadata |
| 434 | * buffers which should be written-back to the filesystem. |
| 435 | */ |
| 436 | |
| 437 | int jbd2_cleanup_journal_tail(journal_t *journal) |
| 438 | { |
| 439 | tid_t first_tid; |
| 440 | unsigned long blocknr; |
| 441 | |
| 442 | if (is_journal_aborted(journal)) |
| 443 | return 1; |
| 444 | |
| 445 | if (!jbd2_journal_get_log_tail(journal, &first_tid, &blocknr)) |
| 446 | return 1; |
| 447 | J_ASSERT(blocknr != 0); |
| 448 | |
| 449 | /* |
| 450 | * We need to make sure that any blocks that were recently written out |
| 451 | * --- perhaps by jbd2_log_do_checkpoint() --- are flushed out before |
| 452 | * we drop the transactions from the journal. It's unlikely this will |
| 453 | * be necessary, especially with an appropriately sized journal, but we |
| 454 | * need this to guarantee correctness. Fortunately |
| 455 | * jbd2_cleanup_journal_tail() doesn't get called all that often. |
| 456 | */ |
| 457 | if (journal->j_flags & JBD2_BARRIER) |
| 458 | blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL); |
| 459 | |
| 460 | __jbd2_update_log_tail(journal, first_tid, blocknr); |
| 461 | return 0; |
| 462 | } |
| 463 | |
| 464 | |
| 465 | /* Checkpoint list management */ |
| 466 | |
| 467 | /* |
| 468 | * journal_clean_one_cp_list |
| 469 | * |
| 470 | * Find all the written-back checkpoint buffers in the given list and |
| 471 | * release them. |
| 472 | * |
| 473 | * Called with the journal locked. |
| 474 | * Called with j_list_lock held. |
| 475 | * Returns number of buffers reaped (for debug) |
| 476 | */ |
| 477 | |
| 478 | static int journal_clean_one_cp_list(struct journal_head *jh, int *released) |
| 479 | { |
| 480 | struct journal_head *last_jh; |
| 481 | struct journal_head *next_jh = jh; |
| 482 | int ret, freed = 0; |
| 483 | |
| 484 | *released = 0; |
| 485 | if (!jh) |
| 486 | return 0; |
| 487 | |
| 488 | last_jh = jh->b_cpprev; |
| 489 | do { |
| 490 | jh = next_jh; |
| 491 | next_jh = jh->b_cpnext; |
| 492 | ret = __try_to_free_cp_buf(jh); |
| 493 | if (ret) { |
| 494 | freed++; |
| 495 | if (ret == 2) { |
| 496 | *released = 1; |
| 497 | return freed; |
| 498 | } |
| 499 | } |
| 500 | /* |
| 501 | * This function only frees up some memory |
| 502 | * if possible so we dont have an obligation |
| 503 | * to finish processing. Bail out if preemption |
| 504 | * requested: |
| 505 | */ |
| 506 | if (need_resched()) |
| 507 | return freed; |
| 508 | } while (jh != last_jh); |
| 509 | |
| 510 | return freed; |
| 511 | } |
| 512 | |
| 513 | /* |
| 514 | * journal_clean_checkpoint_list |
| 515 | * |
| 516 | * Find all the written-back checkpoint buffers in the journal and release them. |
| 517 | * |
| 518 | * Called with the journal locked. |
| 519 | * Called with j_list_lock held. |
| 520 | * Returns number of buffers reaped (for debug) |
| 521 | */ |
| 522 | |
| 523 | int __jbd2_journal_clean_checkpoint_list(journal_t *journal) |
| 524 | { |
| 525 | transaction_t *transaction, *last_transaction, *next_transaction; |
| 526 | int ret = 0; |
| 527 | int released; |
| 528 | |
| 529 | transaction = journal->j_checkpoint_transactions; |
| 530 | if (!transaction) |
| 531 | goto out; |
| 532 | |
| 533 | last_transaction = transaction->t_cpprev; |
| 534 | next_transaction = transaction; |
| 535 | do { |
| 536 | transaction = next_transaction; |
| 537 | next_transaction = transaction->t_cpnext; |
| 538 | ret += journal_clean_one_cp_list(transaction-> |
| 539 | t_checkpoint_list, &released); |
| 540 | /* |
| 541 | * This function only frees up some memory if possible so we |
| 542 | * dont have an obligation to finish processing. Bail out if |
| 543 | * preemption requested: |
| 544 | */ |
| 545 | if (need_resched()) |
| 546 | goto out; |
| 547 | if (released) |
| 548 | continue; |
| 549 | /* |
| 550 | * It is essential that we are as careful as in the case of |
| 551 | * t_checkpoint_list with removing the buffer from the list as |
| 552 | * we can possibly see not yet submitted buffers on io_list |
| 553 | */ |
| 554 | ret += journal_clean_one_cp_list(transaction-> |
| 555 | t_checkpoint_io_list, &released); |
| 556 | if (need_resched()) |
| 557 | goto out; |
| 558 | } while (transaction != last_transaction); |
| 559 | out: |
| 560 | return ret; |
| 561 | } |
| 562 | |
| 563 | /* |
| 564 | * journal_remove_checkpoint: called after a buffer has been committed |
| 565 | * to disk (either by being write-back flushed to disk, or being |
| 566 | * committed to the log). |
| 567 | * |
| 568 | * We cannot safely clean a transaction out of the log until all of the |
| 569 | * buffer updates committed in that transaction have safely been stored |
| 570 | * elsewhere on disk. To achieve this, all of the buffers in a |
| 571 | * transaction need to be maintained on the transaction's checkpoint |
| 572 | * lists until they have been rewritten, at which point this function is |
| 573 | * called to remove the buffer from the existing transaction's |
| 574 | * checkpoint lists. |
| 575 | * |
| 576 | * The function returns 1 if it frees the transaction, 0 otherwise. |
| 577 | * The function can free jh and bh. |
| 578 | * |
| 579 | * This function is called with j_list_lock held. |
| 580 | */ |
| 581 | int __jbd2_journal_remove_checkpoint(struct journal_head *jh) |
| 582 | { |
| 583 | struct transaction_chp_stats_s *stats; |
| 584 | transaction_t *transaction; |
| 585 | journal_t *journal; |
| 586 | int ret = 0; |
| 587 | |
| 588 | JBUFFER_TRACE(jh, "entry"); |
| 589 | |
| 590 | if ((transaction = jh->b_cp_transaction) == NULL) { |
| 591 | JBUFFER_TRACE(jh, "not on transaction"); |
| 592 | goto out; |
| 593 | } |
| 594 | journal = transaction->t_journal; |
| 595 | |
| 596 | JBUFFER_TRACE(jh, "removing from transaction"); |
| 597 | __buffer_unlink(jh); |
| 598 | jh->b_cp_transaction = NULL; |
| 599 | jbd2_journal_put_journal_head(jh); |
| 600 | |
| 601 | if (transaction->t_checkpoint_list != NULL || |
| 602 | transaction->t_checkpoint_io_list != NULL) |
| 603 | goto out; |
| 604 | |
| 605 | /* |
| 606 | * There is one special case to worry about: if we have just pulled the |
| 607 | * buffer off a running or committing transaction's checkpoing list, |
| 608 | * then even if the checkpoint list is empty, the transaction obviously |
| 609 | * cannot be dropped! |
| 610 | * |
| 611 | * The locking here around t_state is a bit sleazy. |
| 612 | * See the comment at the end of jbd2_journal_commit_transaction(). |
| 613 | */ |
| 614 | if (transaction->t_state != T_FINISHED) |
| 615 | goto out; |
| 616 | |
| 617 | /* OK, that was the last buffer for the transaction: we can now |
| 618 | safely remove this transaction from the log */ |
| 619 | stats = &transaction->t_chp_stats; |
| 620 | if (stats->cs_chp_time) |
| 621 | stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time, |
| 622 | jiffies); |
| 623 | trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev, |
| 624 | transaction->t_tid, stats); |
| 625 | |
| 626 | __jbd2_journal_drop_transaction(journal, transaction); |
| 627 | jbd2_journal_free_transaction(transaction); |
| 628 | |
| 629 | /* Just in case anybody was waiting for more transactions to be |
| 630 | checkpointed... */ |
| 631 | wake_up(&journal->j_wait_logspace); |
| 632 | ret = 1; |
| 633 | out: |
| 634 | return ret; |
| 635 | } |
| 636 | |
| 637 | /* |
| 638 | * journal_insert_checkpoint: put a committed buffer onto a checkpoint |
| 639 | * list so that we know when it is safe to clean the transaction out of |
| 640 | * the log. |
| 641 | * |
| 642 | * Called with the journal locked. |
| 643 | * Called with j_list_lock held. |
| 644 | */ |
| 645 | void __jbd2_journal_insert_checkpoint(struct journal_head *jh, |
| 646 | transaction_t *transaction) |
| 647 | { |
| 648 | JBUFFER_TRACE(jh, "entry"); |
| 649 | J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh))); |
| 650 | J_ASSERT_JH(jh, jh->b_cp_transaction == NULL); |
| 651 | |
| 652 | /* Get reference for checkpointing transaction */ |
| 653 | jbd2_journal_grab_journal_head(jh2bh(jh)); |
| 654 | jh->b_cp_transaction = transaction; |
| 655 | |
| 656 | if (!transaction->t_checkpoint_list) { |
| 657 | jh->b_cpnext = jh->b_cpprev = jh; |
| 658 | } else { |
| 659 | jh->b_cpnext = transaction->t_checkpoint_list; |
| 660 | jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev; |
| 661 | jh->b_cpprev->b_cpnext = jh; |
| 662 | jh->b_cpnext->b_cpprev = jh; |
| 663 | } |
| 664 | transaction->t_checkpoint_list = jh; |
| 665 | } |
| 666 | |
| 667 | /* |
| 668 | * We've finished with this transaction structure: adios... |
| 669 | * |
| 670 | * The transaction must have no links except for the checkpoint by this |
| 671 | * point. |
| 672 | * |
| 673 | * Called with the journal locked. |
| 674 | * Called with j_list_lock held. |
| 675 | */ |
| 676 | |
| 677 | void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction) |
| 678 | { |
| 679 | assert_spin_locked(&journal->j_list_lock); |
| 680 | if (transaction->t_cpnext) { |
| 681 | transaction->t_cpnext->t_cpprev = transaction->t_cpprev; |
| 682 | transaction->t_cpprev->t_cpnext = transaction->t_cpnext; |
| 683 | if (journal->j_checkpoint_transactions == transaction) |
| 684 | journal->j_checkpoint_transactions = |
| 685 | transaction->t_cpnext; |
| 686 | if (journal->j_checkpoint_transactions == transaction) |
| 687 | journal->j_checkpoint_transactions = NULL; |
| 688 | } |
| 689 | |
| 690 | J_ASSERT(transaction->t_state == T_FINISHED); |
| 691 | J_ASSERT(transaction->t_buffers == NULL); |
| 692 | J_ASSERT(transaction->t_forget == NULL); |
| 693 | J_ASSERT(transaction->t_shadow_list == NULL); |
| 694 | J_ASSERT(transaction->t_checkpoint_list == NULL); |
| 695 | J_ASSERT(transaction->t_checkpoint_io_list == NULL); |
| 696 | J_ASSERT(atomic_read(&transaction->t_updates) == 0); |
| 697 | J_ASSERT(journal->j_committing_transaction != transaction); |
| 698 | J_ASSERT(journal->j_running_transaction != transaction); |
| 699 | |
| 700 | trace_jbd2_drop_transaction(journal, transaction); |
| 701 | |
| 702 | jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid); |
| 703 | } |