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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 | * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it | |
92 | */ | |
93 | static int __try_to_free_cp_buf(struct journal_head *jh) | |
94 | { | |
95 | int ret = 0; | |
96 | struct buffer_head *bh = jh2bh(jh); | |
97 | ||
98 | if (jh->b_jlist == BJ_None && !buffer_locked(bh) && | |
99 | !buffer_dirty(bh) && !buffer_write_io_error(bh)) { | |
100 | JBUFFER_TRACE(jh, "remove from checkpoint list"); | |
101 | ret = __jbd2_journal_remove_checkpoint(jh) + 1; | |
102 | jbd_unlock_bh_state(bh); | |
103 | jbd2_journal_remove_journal_head(bh); | |
104 | BUFFER_TRACE(bh, "release"); | |
105 | __brelse(bh); | |
106 | } else { | |
107 | jbd_unlock_bh_state(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 | * We were unable to perform jbd_trylock_bh_state() inside j_list_lock. | |
180 | * The caller must restart a list walk. Wait for someone else to run | |
181 | * jbd_unlock_bh_state(). | |
182 | */ | |
183 | static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh) | |
184 | __releases(journal->j_list_lock) | |
185 | { | |
186 | get_bh(bh); | |
187 | spin_unlock(&journal->j_list_lock); | |
188 | jbd_lock_bh_state(bh); | |
189 | jbd_unlock_bh_state(bh); | |
190 | put_bh(bh); | |
191 | } | |
192 | ||
193 | /* | |
194 | * Clean up transaction's list of buffers submitted for io. | |
195 | * We wait for any pending IO to complete and remove any clean | |
196 | * buffers. Note that we take the buffers in the opposite ordering | |
197 | * from the one in which they were submitted for IO. | |
198 | * | |
199 | * Return 0 on success, and return <0 if some buffers have failed | |
200 | * to be written out. | |
201 | * | |
202 | * Called with j_list_lock held. | |
203 | */ | |
204 | static int __wait_cp_io(journal_t *journal, transaction_t *transaction) | |
205 | { | |
206 | struct journal_head *jh; | |
207 | struct buffer_head *bh; | |
208 | tid_t this_tid; | |
209 | int released = 0; | |
210 | int ret = 0; | |
211 | ||
212 | this_tid = transaction->t_tid; | |
213 | restart: | |
214 | /* Did somebody clean up the transaction in the meanwhile? */ | |
215 | if (journal->j_checkpoint_transactions != transaction || | |
216 | transaction->t_tid != this_tid) | |
217 | return ret; | |
218 | while (!released && transaction->t_checkpoint_io_list) { | |
219 | jh = transaction->t_checkpoint_io_list; | |
220 | bh = jh2bh(jh); | |
221 | if (!jbd_trylock_bh_state(bh)) { | |
222 | jbd_sync_bh(journal, bh); | |
223 | spin_lock(&journal->j_list_lock); | |
224 | goto restart; | |
225 | } | |
226 | if (buffer_locked(bh)) { | |
227 | atomic_inc(&bh->b_count); | |
228 | spin_unlock(&journal->j_list_lock); | |
229 | jbd_unlock_bh_state(bh); | |
230 | wait_on_buffer(bh); | |
231 | /* the journal_head may have gone by now */ | |
232 | BUFFER_TRACE(bh, "brelse"); | |
233 | __brelse(bh); | |
234 | spin_lock(&journal->j_list_lock); | |
235 | goto restart; | |
236 | } | |
237 | if (unlikely(buffer_write_io_error(bh))) | |
238 | ret = -EIO; | |
239 | ||
240 | /* | |
241 | * Now in whatever state the buffer currently is, we know that | |
242 | * it has been written out and so we can drop it from the list | |
243 | */ | |
244 | released = __jbd2_journal_remove_checkpoint(jh); | |
245 | jbd_unlock_bh_state(bh); | |
246 | jbd2_journal_remove_journal_head(bh); | |
247 | __brelse(bh); | |
248 | } | |
249 | ||
250 | return ret; | |
251 | } | |
252 | ||
253 | static void | |
254 | __flush_batch(journal_t *journal, int *batch_count) | |
255 | { | |
256 | int i; | |
257 | ||
258 | for (i = 0; i < *batch_count; i++) | |
259 | write_dirty_buffer(journal->j_chkpt_bhs[i], WRITE); | |
260 | ||
261 | for (i = 0; i < *batch_count; i++) { | |
262 | struct buffer_head *bh = journal->j_chkpt_bhs[i]; | |
263 | clear_buffer_jwrite(bh); | |
264 | BUFFER_TRACE(bh, "brelse"); | |
265 | __brelse(bh); | |
266 | } | |
267 | *batch_count = 0; | |
268 | } | |
269 | ||
270 | /* | |
271 | * Try to flush one buffer from the checkpoint list to disk. | |
272 | * | |
273 | * Return 1 if something happened which requires us to abort the current | |
274 | * scan of the checkpoint list. Return <0 if the buffer has failed to | |
275 | * be written out. | |
276 | * | |
277 | * Called with j_list_lock held and drops it if 1 is returned | |
278 | * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it | |
279 | */ | |
280 | static int __process_buffer(journal_t *journal, struct journal_head *jh, | |
281 | int *batch_count, transaction_t *transaction) | |
282 | { | |
283 | struct buffer_head *bh = jh2bh(jh); | |
284 | int ret = 0; | |
285 | ||
286 | if (buffer_locked(bh)) { | |
287 | atomic_inc(&bh->b_count); | |
288 | spin_unlock(&journal->j_list_lock); | |
289 | jbd_unlock_bh_state(bh); | |
290 | wait_on_buffer(bh); | |
291 | /* the journal_head may have gone by now */ | |
292 | BUFFER_TRACE(bh, "brelse"); | |
293 | __brelse(bh); | |
294 | ret = 1; | |
295 | } else if (jh->b_transaction != NULL) { | |
296 | transaction_t *t = jh->b_transaction; | |
297 | tid_t tid = t->t_tid; | |
298 | ||
299 | transaction->t_chp_stats.cs_forced_to_close++; | |
300 | spin_unlock(&journal->j_list_lock); | |
301 | jbd_unlock_bh_state(bh); | |
302 | jbd2_log_start_commit(journal, tid); | |
303 | jbd2_log_wait_commit(journal, tid); | |
304 | ret = 1; | |
305 | } else if (!buffer_dirty(bh)) { | |
306 | ret = 1; | |
307 | if (unlikely(buffer_write_io_error(bh))) | |
308 | ret = -EIO; | |
309 | J_ASSERT_JH(jh, !buffer_jbddirty(bh)); | |
310 | BUFFER_TRACE(bh, "remove from checkpoint"); | |
311 | __jbd2_journal_remove_checkpoint(jh); | |
312 | spin_unlock(&journal->j_list_lock); | |
313 | jbd_unlock_bh_state(bh); | |
314 | jbd2_journal_remove_journal_head(bh); | |
315 | __brelse(bh); | |
316 | } else { | |
317 | /* | |
318 | * Important: we are about to write the buffer, and | |
319 | * possibly block, while still holding the journal lock. | |
320 | * We cannot afford to let the transaction logic start | |
321 | * messing around with this buffer before we write it to | |
322 | * disk, as that would break recoverability. | |
323 | */ | |
324 | BUFFER_TRACE(bh, "queue"); | |
325 | get_bh(bh); | |
326 | J_ASSERT_BH(bh, !buffer_jwrite(bh)); | |
327 | set_buffer_jwrite(bh); | |
328 | journal->j_chkpt_bhs[*batch_count] = bh; | |
329 | __buffer_relink_io(jh); | |
330 | jbd_unlock_bh_state(bh); | |
331 | transaction->t_chp_stats.cs_written++; | |
332 | (*batch_count)++; | |
333 | if (*batch_count == JBD2_NR_BATCH) { | |
334 | spin_unlock(&journal->j_list_lock); | |
335 | __flush_batch(journal, batch_count); | |
336 | ret = 1; | |
337 | } | |
338 | } | |
339 | return ret; | |
340 | } | |
341 | ||
342 | /* | |
343 | * Perform an actual checkpoint. We take the first transaction on the | |
344 | * list of transactions to be checkpointed and send all its buffers | |
345 | * to disk. We submit larger chunks of data at once. | |
346 | * | |
347 | * The journal should be locked before calling this function. | |
348 | * Called with j_checkpoint_mutex held. | |
349 | */ | |
350 | int jbd2_log_do_checkpoint(journal_t *journal) | |
351 | { | |
352 | transaction_t *transaction; | |
353 | tid_t this_tid; | |
354 | int result; | |
355 | ||
356 | jbd_debug(1, "Start checkpoint\n"); | |
357 | ||
358 | /* | |
359 | * First thing: if there are any transactions in the log which | |
360 | * don't need checkpointing, just eliminate them from the | |
361 | * journal straight away. | |
362 | */ | |
363 | result = jbd2_cleanup_journal_tail(journal); | |
364 | trace_jbd2_checkpoint(journal, result); | |
365 | jbd_debug(1, "cleanup_journal_tail returned %d\n", result); | |
366 | if (result <= 0) | |
367 | return result; | |
368 | ||
369 | /* | |
370 | * OK, we need to start writing disk blocks. Take one transaction | |
371 | * and write it. | |
372 | */ | |
373 | result = 0; | |
374 | spin_lock(&journal->j_list_lock); | |
375 | if (!journal->j_checkpoint_transactions) | |
376 | goto out; | |
377 | transaction = journal->j_checkpoint_transactions; | |
378 | if (transaction->t_chp_stats.cs_chp_time == 0) | |
379 | transaction->t_chp_stats.cs_chp_time = jiffies; | |
380 | this_tid = transaction->t_tid; | |
381 | restart: | |
382 | /* | |
383 | * If someone cleaned up this transaction while we slept, we're | |
384 | * done (maybe it's a new transaction, but it fell at the same | |
385 | * address). | |
386 | */ | |
387 | if (journal->j_checkpoint_transactions == transaction && | |
388 | transaction->t_tid == this_tid) { | |
389 | int batch_count = 0; | |
390 | struct journal_head *jh; | |
391 | int retry = 0, err; | |
392 | ||
393 | while (!retry && transaction->t_checkpoint_list) { | |
394 | struct buffer_head *bh; | |
395 | ||
396 | jh = transaction->t_checkpoint_list; | |
397 | bh = jh2bh(jh); | |
398 | if (!jbd_trylock_bh_state(bh)) { | |
399 | jbd_sync_bh(journal, bh); | |
400 | retry = 1; | |
401 | break; | |
402 | } | |
403 | retry = __process_buffer(journal, jh, &batch_count, | |
404 | transaction); | |
405 | if (retry < 0 && !result) | |
406 | result = retry; | |
407 | if (!retry && (need_resched() || | |
408 | spin_needbreak(&journal->j_list_lock))) { | |
409 | spin_unlock(&journal->j_list_lock); | |
410 | retry = 1; | |
411 | break; | |
412 | } | |
413 | } | |
414 | ||
415 | if (batch_count) { | |
416 | if (!retry) { | |
417 | spin_unlock(&journal->j_list_lock); | |
418 | retry = 1; | |
419 | } | |
420 | __flush_batch(journal, &batch_count); | |
421 | } | |
422 | ||
423 | if (retry) { | |
424 | spin_lock(&journal->j_list_lock); | |
425 | goto restart; | |
426 | } | |
427 | /* | |
428 | * Now we have cleaned up the first transaction's checkpoint | |
429 | * list. Let's clean up the second one | |
430 | */ | |
431 | err = __wait_cp_io(journal, transaction); | |
432 | if (!result) | |
433 | result = err; | |
434 | } | |
435 | out: | |
436 | spin_unlock(&journal->j_list_lock); | |
437 | if (result < 0) | |
438 | jbd2_journal_abort(journal, result); | |
439 | else | |
440 | result = jbd2_cleanup_journal_tail(journal); | |
441 | ||
442 | return (result < 0) ? result : 0; | |
443 | } | |
444 | ||
445 | /* | |
446 | * Check the list of checkpoint transactions for the journal to see if | |
447 | * we have already got rid of any since the last update of the log tail | |
448 | * in the journal superblock. If so, we can instantly roll the | |
449 | * superblock forward to remove those transactions from the log. | |
450 | * | |
451 | * Return <0 on error, 0 on success, 1 if there was nothing to clean up. | |
452 | * | |
453 | * Called with the journal lock held. | |
454 | * | |
455 | * This is the only part of the journaling code which really needs to be | |
456 | * aware of transaction aborts. Checkpointing involves writing to the | |
457 | * main filesystem area rather than to the journal, so it can proceed | |
458 | * even in abort state, but we must not update the super block if | |
459 | * checkpointing may have failed. Otherwise, we would lose some metadata | |
460 | * buffers which should be written-back to the filesystem. | |
461 | */ | |
462 | ||
463 | int jbd2_cleanup_journal_tail(journal_t *journal) | |
464 | { | |
465 | transaction_t * transaction; | |
466 | tid_t first_tid; | |
467 | unsigned long blocknr, freed; | |
468 | ||
469 | if (is_journal_aborted(journal)) | |
470 | return 1; | |
471 | ||
472 | /* OK, work out the oldest transaction remaining in the log, and | |
473 | * the log block it starts at. | |
474 | * | |
475 | * If the log is now empty, we need to work out which is the | |
476 | * next transaction ID we will write, and where it will | |
477 | * start. */ | |
478 | ||
479 | write_lock(&journal->j_state_lock); | |
480 | spin_lock(&journal->j_list_lock); | |
481 | transaction = journal->j_checkpoint_transactions; | |
482 | if (transaction) { | |
483 | first_tid = transaction->t_tid; | |
484 | blocknr = transaction->t_log_start; | |
485 | } else if ((transaction = journal->j_committing_transaction) != NULL) { | |
486 | first_tid = transaction->t_tid; | |
487 | blocknr = transaction->t_log_start; | |
488 | } else if ((transaction = journal->j_running_transaction) != NULL) { | |
489 | first_tid = transaction->t_tid; | |
490 | blocknr = journal->j_head; | |
491 | } else { | |
492 | first_tid = journal->j_transaction_sequence; | |
493 | blocknr = journal->j_head; | |
494 | } | |
495 | spin_unlock(&journal->j_list_lock); | |
496 | J_ASSERT(blocknr != 0); | |
497 | ||
498 | /* If the oldest pinned transaction is at the tail of the log | |
499 | already then there's not much we can do right now. */ | |
500 | if (journal->j_tail_sequence == first_tid) { | |
501 | write_unlock(&journal->j_state_lock); | |
502 | return 1; | |
503 | } | |
504 | ||
505 | /* OK, update the superblock to recover the freed space. | |
506 | * Physical blocks come first: have we wrapped beyond the end of | |
507 | * the log? */ | |
508 | freed = blocknr - journal->j_tail; | |
509 | if (blocknr < journal->j_tail) | |
510 | freed = freed + journal->j_last - journal->j_first; | |
511 | ||
512 | trace_jbd2_cleanup_journal_tail(journal, first_tid, blocknr, freed); | |
513 | jbd_debug(1, | |
514 | "Cleaning journal tail from %d to %d (offset %lu), " | |
515 | "freeing %lu\n", | |
516 | journal->j_tail_sequence, first_tid, blocknr, freed); | |
517 | ||
518 | journal->j_free += freed; | |
519 | journal->j_tail_sequence = first_tid; | |
520 | journal->j_tail = blocknr; | |
521 | write_unlock(&journal->j_state_lock); | |
522 | ||
523 | /* | |
524 | * If there is an external journal, we need to make sure that | |
525 | * any data blocks that were recently written out --- perhaps | |
526 | * by jbd2_log_do_checkpoint() --- are flushed out before we | |
527 | * drop the transactions from the external journal. It's | |
528 | * unlikely this will be necessary, especially with a | |
529 | * appropriately sized journal, but we need this to guarantee | |
530 | * correctness. Fortunately jbd2_cleanup_journal_tail() | |
531 | * doesn't get called all that often. | |
532 | */ | |
533 | if ((journal->j_fs_dev != journal->j_dev) && | |
534 | (journal->j_flags & JBD2_BARRIER)) | |
535 | blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL, | |
536 | BLKDEV_IFL_WAIT); | |
537 | if (!(journal->j_flags & JBD2_ABORT)) | |
538 | jbd2_journal_update_superblock(journal, 1); | |
539 | return 0; | |
540 | } | |
541 | ||
542 | ||
543 | /* Checkpoint list management */ | |
544 | ||
545 | /* | |
546 | * journal_clean_one_cp_list | |
547 | * | |
548 | * Find all the written-back checkpoint buffers in the given list and release them. | |
549 | * | |
550 | * Called with the journal locked. | |
551 | * Called with j_list_lock held. | |
552 | * Returns number of bufers reaped (for debug) | |
553 | */ | |
554 | ||
555 | static int journal_clean_one_cp_list(struct journal_head *jh, int *released) | |
556 | { | |
557 | struct journal_head *last_jh; | |
558 | struct journal_head *next_jh = jh; | |
559 | int ret, freed = 0; | |
560 | ||
561 | *released = 0; | |
562 | if (!jh) | |
563 | return 0; | |
564 | ||
565 | last_jh = jh->b_cpprev; | |
566 | do { | |
567 | jh = next_jh; | |
568 | next_jh = jh->b_cpnext; | |
569 | /* Use trylock because of the ranking */ | |
570 | if (jbd_trylock_bh_state(jh2bh(jh))) { | |
571 | ret = __try_to_free_cp_buf(jh); | |
572 | if (ret) { | |
573 | freed++; | |
574 | if (ret == 2) { | |
575 | *released = 1; | |
576 | return freed; | |
577 | } | |
578 | } | |
579 | } | |
580 | /* | |
581 | * This function only frees up some memory | |
582 | * if possible so we dont have an obligation | |
583 | * to finish processing. Bail out if preemption | |
584 | * requested: | |
585 | */ | |
586 | if (need_resched()) | |
587 | return freed; | |
588 | } while (jh != last_jh); | |
589 | ||
590 | return freed; | |
591 | } | |
592 | ||
593 | /* | |
594 | * journal_clean_checkpoint_list | |
595 | * | |
596 | * Find all the written-back checkpoint buffers in the journal and release them. | |
597 | * | |
598 | * Called with the journal locked. | |
599 | * Called with j_list_lock held. | |
600 | * Returns number of buffers reaped (for debug) | |
601 | */ | |
602 | ||
603 | int __jbd2_journal_clean_checkpoint_list(journal_t *journal) | |
604 | { | |
605 | transaction_t *transaction, *last_transaction, *next_transaction; | |
606 | int ret = 0; | |
607 | int released; | |
608 | ||
609 | transaction = journal->j_checkpoint_transactions; | |
610 | if (!transaction) | |
611 | goto out; | |
612 | ||
613 | last_transaction = transaction->t_cpprev; | |
614 | next_transaction = transaction; | |
615 | do { | |
616 | transaction = next_transaction; | |
617 | next_transaction = transaction->t_cpnext; | |
618 | ret += journal_clean_one_cp_list(transaction-> | |
619 | t_checkpoint_list, &released); | |
620 | /* | |
621 | * This function only frees up some memory if possible so we | |
622 | * dont have an obligation to finish processing. Bail out if | |
623 | * preemption requested: | |
624 | */ | |
625 | if (need_resched()) | |
626 | goto out; | |
627 | if (released) | |
628 | continue; | |
629 | /* | |
630 | * It is essential that we are as careful as in the case of | |
631 | * t_checkpoint_list with removing the buffer from the list as | |
632 | * we can possibly see not yet submitted buffers on io_list | |
633 | */ | |
634 | ret += journal_clean_one_cp_list(transaction-> | |
635 | t_checkpoint_io_list, &released); | |
636 | if (need_resched()) | |
637 | goto out; | |
638 | } while (transaction != last_transaction); | |
639 | out: | |
640 | return ret; | |
641 | } | |
642 | ||
643 | /* | |
644 | * journal_remove_checkpoint: called after a buffer has been committed | |
645 | * to disk (either by being write-back flushed to disk, or being | |
646 | * committed to the log). | |
647 | * | |
648 | * We cannot safely clean a transaction out of the log until all of the | |
649 | * buffer updates committed in that transaction have safely been stored | |
650 | * elsewhere on disk. To achieve this, all of the buffers in a | |
651 | * transaction need to be maintained on the transaction's checkpoint | |
652 | * lists until they have been rewritten, at which point this function is | |
653 | * called to remove the buffer from the existing transaction's | |
654 | * checkpoint lists. | |
655 | * | |
656 | * The function returns 1 if it frees the transaction, 0 otherwise. | |
657 | * | |
658 | * This function is called with the journal locked. | |
659 | * This function is called with j_list_lock held. | |
660 | * This function is called with jbd_lock_bh_state(jh2bh(jh)) | |
661 | */ | |
662 | ||
663 | int __jbd2_journal_remove_checkpoint(struct journal_head *jh) | |
664 | { | |
665 | struct transaction_chp_stats_s *stats; | |
666 | transaction_t *transaction; | |
667 | journal_t *journal; | |
668 | int ret = 0; | |
669 | ||
670 | JBUFFER_TRACE(jh, "entry"); | |
671 | ||
672 | if ((transaction = jh->b_cp_transaction) == NULL) { | |
673 | JBUFFER_TRACE(jh, "not on transaction"); | |
674 | goto out; | |
675 | } | |
676 | journal = transaction->t_journal; | |
677 | ||
678 | __buffer_unlink(jh); | |
679 | jh->b_cp_transaction = NULL; | |
680 | ||
681 | if (transaction->t_checkpoint_list != NULL || | |
682 | transaction->t_checkpoint_io_list != NULL) | |
683 | goto out; | |
684 | JBUFFER_TRACE(jh, "transaction has no more buffers"); | |
685 | ||
686 | /* | |
687 | * There is one special case to worry about: if we have just pulled the | |
688 | * buffer off a running or committing transaction's checkpoing list, | |
689 | * then even if the checkpoint list is empty, the transaction obviously | |
690 | * cannot be dropped! | |
691 | * | |
692 | * The locking here around t_state is a bit sleazy. | |
693 | * See the comment at the end of jbd2_journal_commit_transaction(). | |
694 | */ | |
695 | if (transaction->t_state != T_FINISHED) { | |
696 | JBUFFER_TRACE(jh, "belongs to running/committing transaction"); | |
697 | goto out; | |
698 | } | |
699 | ||
700 | /* OK, that was the last buffer for the transaction: we can now | |
701 | safely remove this transaction from the log */ | |
702 | stats = &transaction->t_chp_stats; | |
703 | if (stats->cs_chp_time) | |
704 | stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time, | |
705 | jiffies); | |
706 | trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev, | |
707 | transaction->t_tid, stats); | |
708 | ||
709 | __jbd2_journal_drop_transaction(journal, transaction); | |
710 | kfree(transaction); | |
711 | ||
712 | /* Just in case anybody was waiting for more transactions to be | |
713 | checkpointed... */ | |
714 | wake_up(&journal->j_wait_logspace); | |
715 | ret = 1; | |
716 | out: | |
717 | JBUFFER_TRACE(jh, "exit"); | |
718 | return ret; | |
719 | } | |
720 | ||
721 | /* | |
722 | * journal_insert_checkpoint: put a committed buffer onto a checkpoint | |
723 | * list so that we know when it is safe to clean the transaction out of | |
724 | * the log. | |
725 | * | |
726 | * Called with the journal locked. | |
727 | * Called with j_list_lock held. | |
728 | */ | |
729 | void __jbd2_journal_insert_checkpoint(struct journal_head *jh, | |
730 | transaction_t *transaction) | |
731 | { | |
732 | JBUFFER_TRACE(jh, "entry"); | |
733 | J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh))); | |
734 | J_ASSERT_JH(jh, jh->b_cp_transaction == NULL); | |
735 | ||
736 | jh->b_cp_transaction = transaction; | |
737 | ||
738 | if (!transaction->t_checkpoint_list) { | |
739 | jh->b_cpnext = jh->b_cpprev = jh; | |
740 | } else { | |
741 | jh->b_cpnext = transaction->t_checkpoint_list; | |
742 | jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev; | |
743 | jh->b_cpprev->b_cpnext = jh; | |
744 | jh->b_cpnext->b_cpprev = jh; | |
745 | } | |
746 | transaction->t_checkpoint_list = jh; | |
747 | } | |
748 | ||
749 | /* | |
750 | * We've finished with this transaction structure: adios... | |
751 | * | |
752 | * The transaction must have no links except for the checkpoint by this | |
753 | * point. | |
754 | * | |
755 | * Called with the journal locked. | |
756 | * Called with j_list_lock held. | |
757 | */ | |
758 | ||
759 | void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction) | |
760 | { | |
761 | assert_spin_locked(&journal->j_list_lock); | |
762 | if (transaction->t_cpnext) { | |
763 | transaction->t_cpnext->t_cpprev = transaction->t_cpprev; | |
764 | transaction->t_cpprev->t_cpnext = transaction->t_cpnext; | |
765 | if (journal->j_checkpoint_transactions == transaction) | |
766 | journal->j_checkpoint_transactions = | |
767 | transaction->t_cpnext; | |
768 | if (journal->j_checkpoint_transactions == transaction) | |
769 | journal->j_checkpoint_transactions = NULL; | |
770 | } | |
771 | ||
772 | J_ASSERT(transaction->t_state == T_FINISHED); | |
773 | J_ASSERT(transaction->t_buffers == NULL); | |
774 | J_ASSERT(transaction->t_forget == NULL); | |
775 | J_ASSERT(transaction->t_iobuf_list == NULL); | |
776 | J_ASSERT(transaction->t_shadow_list == NULL); | |
777 | J_ASSERT(transaction->t_log_list == NULL); | |
778 | J_ASSERT(transaction->t_checkpoint_list == NULL); | |
779 | J_ASSERT(transaction->t_checkpoint_io_list == NULL); | |
780 | J_ASSERT(atomic_read(&transaction->t_updates) == 0); | |
781 | J_ASSERT(journal->j_committing_transaction != transaction); | |
782 | J_ASSERT(journal->j_running_transaction != transaction); | |
783 | ||
784 | jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid); | |
785 | } |