Commit | Line | Data |
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470decc6 | 1 | /* |
58862699 | 2 | * linux/fs/jbd2/checkpoint.c |
470decc6 DK |
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> | |
f7f4bccb | 22 | #include <linux/jbd2.h> |
ede86cc4 | 23 | #include <linux/marker.h> |
470decc6 DK |
24 | #include <linux/errno.h> |
25 | #include <linux/slab.h> | |
26 | ||
27 | /* | |
28 | * Unlink a buffer from a transaction checkpoint list. | |
29 | * | |
30 | * Called with j_list_lock held. | |
31 | */ | |
32 | static inline void __buffer_unlink_first(struct journal_head *jh) | |
33 | { | |
34 | transaction_t *transaction = jh->b_cp_transaction; | |
35 | ||
36 | jh->b_cpnext->b_cpprev = jh->b_cpprev; | |
37 | jh->b_cpprev->b_cpnext = jh->b_cpnext; | |
38 | if (transaction->t_checkpoint_list == jh) { | |
39 | transaction->t_checkpoint_list = jh->b_cpnext; | |
40 | if (transaction->t_checkpoint_list == jh) | |
41 | transaction->t_checkpoint_list = NULL; | |
42 | } | |
43 | } | |
44 | ||
45 | /* | |
46 | * Unlink a buffer from a transaction checkpoint(io) list. | |
47 | * | |
48 | * Called with j_list_lock held. | |
49 | */ | |
50 | static inline void __buffer_unlink(struct journal_head *jh) | |
51 | { | |
52 | transaction_t *transaction = jh->b_cp_transaction; | |
53 | ||
54 | __buffer_unlink_first(jh); | |
55 | if (transaction->t_checkpoint_io_list == jh) { | |
56 | transaction->t_checkpoint_io_list = jh->b_cpnext; | |
57 | if (transaction->t_checkpoint_io_list == jh) | |
58 | transaction->t_checkpoint_io_list = NULL; | |
59 | } | |
60 | } | |
61 | ||
62 | /* | |
63 | * Move a buffer from the checkpoint list to the checkpoint io list | |
64 | * | |
65 | * Called with j_list_lock held | |
66 | */ | |
67 | static inline void __buffer_relink_io(struct journal_head *jh) | |
68 | { | |
69 | transaction_t *transaction = jh->b_cp_transaction; | |
70 | ||
71 | __buffer_unlink_first(jh); | |
72 | ||
73 | if (!transaction->t_checkpoint_io_list) { | |
74 | jh->b_cpnext = jh->b_cpprev = jh; | |
75 | } else { | |
76 | jh->b_cpnext = transaction->t_checkpoint_io_list; | |
77 | jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev; | |
78 | jh->b_cpprev->b_cpnext = jh; | |
79 | jh->b_cpnext->b_cpprev = jh; | |
80 | } | |
81 | transaction->t_checkpoint_io_list = jh; | |
82 | } | |
83 | ||
84 | /* | |
85 | * Try to release a checkpointed buffer from its transaction. | |
86 | * Returns 1 if we released it and 2 if we also released the | |
87 | * whole transaction. | |
88 | * | |
89 | * Requires j_list_lock | |
90 | * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it | |
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_jlist == BJ_None && !buffer_locked(bh) && !buffer_dirty(bh)) { | |
98 | JBUFFER_TRACE(jh, "remove from checkpoint list"); | |
f7f4bccb | 99 | ret = __jbd2_journal_remove_checkpoint(jh) + 1; |
470decc6 | 100 | jbd_unlock_bh_state(bh); |
f7f4bccb | 101 | jbd2_journal_remove_journal_head(bh); |
470decc6 DK |
102 | BUFFER_TRACE(bh, "release"); |
103 | __brelse(bh); | |
104 | } else { | |
105 | jbd_unlock_bh_state(bh); | |
106 | } | |
107 | return ret; | |
108 | } | |
109 | ||
110 | /* | |
f7f4bccb | 111 | * __jbd2_log_wait_for_space: wait until there is space in the journal. |
470decc6 DK |
112 | * |
113 | * Called under j-state_lock *only*. It will be unlocked if we have to wait | |
114 | * for a checkpoint to free up some space in the log. | |
115 | */ | |
f7f4bccb | 116 | void __jbd2_log_wait_for_space(journal_t *journal) |
470decc6 DK |
117 | { |
118 | int nblocks; | |
119 | assert_spin_locked(&journal->j_state_lock); | |
120 | ||
121 | nblocks = jbd_space_needed(journal); | |
f7f4bccb MC |
122 | while (__jbd2_log_space_left(journal) < nblocks) { |
123 | if (journal->j_flags & JBD2_ABORT) | |
470decc6 DK |
124 | return; |
125 | spin_unlock(&journal->j_state_lock); | |
126 | mutex_lock(&journal->j_checkpoint_mutex); | |
127 | ||
128 | /* | |
129 | * Test again, another process may have checkpointed while we | |
23f8b79e DG |
130 | * were waiting for the checkpoint lock. If there are no |
131 | * outstanding transactions there is nothing to checkpoint and | |
132 | * we can't make progress. Abort the journal in this case. | |
470decc6 DK |
133 | */ |
134 | spin_lock(&journal->j_state_lock); | |
23f8b79e | 135 | spin_lock(&journal->j_list_lock); |
470decc6 | 136 | nblocks = jbd_space_needed(journal); |
f7f4bccb | 137 | if (__jbd2_log_space_left(journal) < nblocks) { |
23f8b79e DG |
138 | int chkpt = journal->j_checkpoint_transactions != NULL; |
139 | ||
140 | spin_unlock(&journal->j_list_lock); | |
470decc6 | 141 | spin_unlock(&journal->j_state_lock); |
23f8b79e DG |
142 | if (chkpt) { |
143 | jbd2_log_do_checkpoint(journal); | |
144 | } else { | |
145 | printk(KERN_ERR "%s: no transactions\n", | |
146 | __func__); | |
147 | jbd2_journal_abort(journal, 0); | |
148 | } | |
149 | ||
470decc6 | 150 | spin_lock(&journal->j_state_lock); |
23f8b79e DG |
151 | } else { |
152 | spin_unlock(&journal->j_list_lock); | |
470decc6 DK |
153 | } |
154 | mutex_unlock(&journal->j_checkpoint_mutex); | |
155 | } | |
156 | } | |
157 | ||
158 | /* | |
159 | * We were unable to perform jbd_trylock_bh_state() inside j_list_lock. | |
160 | * The caller must restart a list walk. Wait for someone else to run | |
161 | * jbd_unlock_bh_state(). | |
162 | */ | |
163 | static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh) | |
164 | __releases(journal->j_list_lock) | |
165 | { | |
166 | get_bh(bh); | |
167 | spin_unlock(&journal->j_list_lock); | |
168 | jbd_lock_bh_state(bh); | |
169 | jbd_unlock_bh_state(bh); | |
170 | put_bh(bh); | |
171 | } | |
172 | ||
173 | /* | |
174 | * Clean up transaction's list of buffers submitted for io. | |
175 | * We wait for any pending IO to complete and remove any clean | |
176 | * buffers. Note that we take the buffers in the opposite ordering | |
177 | * from the one in which they were submitted for IO. | |
178 | * | |
179 | * Called with j_list_lock held. | |
180 | */ | |
181 | static void __wait_cp_io(journal_t *journal, transaction_t *transaction) | |
182 | { | |
183 | struct journal_head *jh; | |
184 | struct buffer_head *bh; | |
185 | tid_t this_tid; | |
186 | int released = 0; | |
187 | ||
188 | this_tid = transaction->t_tid; | |
189 | restart: | |
190 | /* Did somebody clean up the transaction in the meanwhile? */ | |
191 | if (journal->j_checkpoint_transactions != transaction || | |
192 | transaction->t_tid != this_tid) | |
193 | return; | |
194 | while (!released && transaction->t_checkpoint_io_list) { | |
195 | jh = transaction->t_checkpoint_io_list; | |
196 | bh = jh2bh(jh); | |
197 | if (!jbd_trylock_bh_state(bh)) { | |
198 | jbd_sync_bh(journal, bh); | |
199 | spin_lock(&journal->j_list_lock); | |
200 | goto restart; | |
201 | } | |
202 | if (buffer_locked(bh)) { | |
203 | atomic_inc(&bh->b_count); | |
204 | spin_unlock(&journal->j_list_lock); | |
205 | jbd_unlock_bh_state(bh); | |
206 | wait_on_buffer(bh); | |
207 | /* the journal_head may have gone by now */ | |
208 | BUFFER_TRACE(bh, "brelse"); | |
209 | __brelse(bh); | |
210 | spin_lock(&journal->j_list_lock); | |
211 | goto restart; | |
212 | } | |
213 | /* | |
214 | * Now in whatever state the buffer currently is, we know that | |
215 | * it has been written out and so we can drop it from the list | |
216 | */ | |
f7f4bccb | 217 | released = __jbd2_journal_remove_checkpoint(jh); |
470decc6 | 218 | jbd_unlock_bh_state(bh); |
f7f4bccb | 219 | jbd2_journal_remove_journal_head(bh); |
470decc6 DK |
220 | __brelse(bh); |
221 | } | |
222 | } | |
223 | ||
224 | #define NR_BATCH 64 | |
225 | ||
226 | static void | |
227 | __flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count) | |
228 | { | |
229 | int i; | |
230 | ||
231 | ll_rw_block(SWRITE, *batch_count, bhs); | |
232 | for (i = 0; i < *batch_count; i++) { | |
233 | struct buffer_head *bh = bhs[i]; | |
234 | clear_buffer_jwrite(bh); | |
235 | BUFFER_TRACE(bh, "brelse"); | |
236 | __brelse(bh); | |
237 | } | |
238 | *batch_count = 0; | |
239 | } | |
240 | ||
241 | /* | |
242 | * Try to flush one buffer from the checkpoint list to disk. | |
243 | * | |
244 | * Return 1 if something happened which requires us to abort the current | |
245 | * scan of the checkpoint list. | |
246 | * | |
247 | * Called with j_list_lock held and drops it if 1 is returned | |
248 | * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it | |
249 | */ | |
250 | static int __process_buffer(journal_t *journal, struct journal_head *jh, | |
8e85fb3f JL |
251 | struct buffer_head **bhs, int *batch_count, |
252 | transaction_t *transaction) | |
470decc6 DK |
253 | { |
254 | struct buffer_head *bh = jh2bh(jh); | |
255 | int ret = 0; | |
256 | ||
257 | if (buffer_locked(bh)) { | |
258 | atomic_inc(&bh->b_count); | |
259 | spin_unlock(&journal->j_list_lock); | |
260 | jbd_unlock_bh_state(bh); | |
261 | wait_on_buffer(bh); | |
262 | /* the journal_head may have gone by now */ | |
263 | BUFFER_TRACE(bh, "brelse"); | |
264 | __brelse(bh); | |
265 | ret = 1; | |
266 | } else if (jh->b_transaction != NULL) { | |
267 | transaction_t *t = jh->b_transaction; | |
268 | tid_t tid = t->t_tid; | |
269 | ||
8e85fb3f | 270 | transaction->t_chp_stats.cs_forced_to_close++; |
470decc6 DK |
271 | spin_unlock(&journal->j_list_lock); |
272 | jbd_unlock_bh_state(bh); | |
f7f4bccb MC |
273 | jbd2_log_start_commit(journal, tid); |
274 | jbd2_log_wait_commit(journal, tid); | |
470decc6 DK |
275 | ret = 1; |
276 | } else if (!buffer_dirty(bh)) { | |
277 | J_ASSERT_JH(jh, !buffer_jbddirty(bh)); | |
278 | BUFFER_TRACE(bh, "remove from checkpoint"); | |
f7f4bccb | 279 | __jbd2_journal_remove_checkpoint(jh); |
470decc6 DK |
280 | spin_unlock(&journal->j_list_lock); |
281 | jbd_unlock_bh_state(bh); | |
f7f4bccb | 282 | jbd2_journal_remove_journal_head(bh); |
470decc6 DK |
283 | __brelse(bh); |
284 | ret = 1; | |
285 | } else { | |
286 | /* | |
287 | * Important: we are about to write the buffer, and | |
288 | * possibly block, while still holding the journal lock. | |
289 | * We cannot afford to let the transaction logic start | |
290 | * messing around with this buffer before we write it to | |
291 | * disk, as that would break recoverability. | |
292 | */ | |
293 | BUFFER_TRACE(bh, "queue"); | |
294 | get_bh(bh); | |
295 | J_ASSERT_BH(bh, !buffer_jwrite(bh)); | |
296 | set_buffer_jwrite(bh); | |
297 | bhs[*batch_count] = bh; | |
298 | __buffer_relink_io(jh); | |
299 | jbd_unlock_bh_state(bh); | |
8e85fb3f | 300 | transaction->t_chp_stats.cs_written++; |
470decc6 DK |
301 | (*batch_count)++; |
302 | if (*batch_count == NR_BATCH) { | |
303 | spin_unlock(&journal->j_list_lock); | |
304 | __flush_batch(journal, bhs, batch_count); | |
305 | ret = 1; | |
306 | } | |
307 | } | |
308 | return ret; | |
309 | } | |
310 | ||
311 | /* | |
312 | * Perform an actual checkpoint. We take the first transaction on the | |
313 | * list of transactions to be checkpointed and send all its buffers | |
314 | * to disk. We submit larger chunks of data at once. | |
315 | * | |
316 | * The journal should be locked before calling this function. | |
317 | */ | |
f7f4bccb | 318 | int jbd2_log_do_checkpoint(journal_t *journal) |
470decc6 DK |
319 | { |
320 | transaction_t *transaction; | |
321 | tid_t this_tid; | |
322 | int result; | |
323 | ||
324 | jbd_debug(1, "Start checkpoint\n"); | |
325 | ||
326 | /* | |
327 | * First thing: if there are any transactions in the log which | |
328 | * don't need checkpointing, just eliminate them from the | |
329 | * journal straight away. | |
330 | */ | |
f7f4bccb | 331 | result = jbd2_cleanup_journal_tail(journal); |
ede86cc4 TT |
332 | trace_mark(jbd2_checkpoint, "dev %s need_checkpoint %d", |
333 | journal->j_devname, result); | |
470decc6 DK |
334 | jbd_debug(1, "cleanup_journal_tail returned %d\n", result); |
335 | if (result <= 0) | |
336 | return result; | |
337 | ||
338 | /* | |
339 | * OK, we need to start writing disk blocks. Take one transaction | |
340 | * and write it. | |
341 | */ | |
342 | spin_lock(&journal->j_list_lock); | |
343 | if (!journal->j_checkpoint_transactions) | |
344 | goto out; | |
345 | transaction = journal->j_checkpoint_transactions; | |
8e85fb3f JL |
346 | if (transaction->t_chp_stats.cs_chp_time == 0) |
347 | transaction->t_chp_stats.cs_chp_time = jiffies; | |
470decc6 DK |
348 | this_tid = transaction->t_tid; |
349 | restart: | |
350 | /* | |
351 | * If someone cleaned up this transaction while we slept, we're | |
352 | * done (maybe it's a new transaction, but it fell at the same | |
353 | * address). | |
354 | */ | |
355 | if (journal->j_checkpoint_transactions == transaction && | |
356 | transaction->t_tid == this_tid) { | |
357 | int batch_count = 0; | |
358 | struct buffer_head *bhs[NR_BATCH]; | |
359 | struct journal_head *jh; | |
360 | int retry = 0; | |
361 | ||
362 | while (!retry && transaction->t_checkpoint_list) { | |
363 | struct buffer_head *bh; | |
364 | ||
365 | jh = transaction->t_checkpoint_list; | |
366 | bh = jh2bh(jh); | |
367 | if (!jbd_trylock_bh_state(bh)) { | |
368 | jbd_sync_bh(journal, bh); | |
369 | retry = 1; | |
370 | break; | |
371 | } | |
8e85fb3f JL |
372 | retry = __process_buffer(journal, jh, bhs, &batch_count, |
373 | transaction); | |
95c354fe NP |
374 | if (!retry && (need_resched() || |
375 | spin_needbreak(&journal->j_list_lock))) { | |
470decc6 DK |
376 | spin_unlock(&journal->j_list_lock); |
377 | retry = 1; | |
378 | break; | |
379 | } | |
380 | } | |
381 | ||
382 | if (batch_count) { | |
383 | if (!retry) { | |
384 | spin_unlock(&journal->j_list_lock); | |
385 | retry = 1; | |
386 | } | |
387 | __flush_batch(journal, bhs, &batch_count); | |
388 | } | |
389 | ||
390 | if (retry) { | |
391 | spin_lock(&journal->j_list_lock); | |
392 | goto restart; | |
393 | } | |
394 | /* | |
395 | * Now we have cleaned up the first transaction's checkpoint | |
396 | * list. Let's clean up the second one | |
397 | */ | |
398 | __wait_cp_io(journal, transaction); | |
399 | } | |
400 | out: | |
401 | spin_unlock(&journal->j_list_lock); | |
f7f4bccb | 402 | result = jbd2_cleanup_journal_tail(journal); |
470decc6 DK |
403 | if (result < 0) |
404 | return result; | |
405 | return 0; | |
406 | } | |
407 | ||
408 | /* | |
409 | * Check the list of checkpoint transactions for the journal to see if | |
410 | * we have already got rid of any since the last update of the log tail | |
411 | * in the journal superblock. If so, we can instantly roll the | |
412 | * superblock forward to remove those transactions from the log. | |
413 | * | |
414 | * Return <0 on error, 0 on success, 1 if there was nothing to clean up. | |
415 | * | |
416 | * Called with the journal lock held. | |
417 | * | |
418 | * This is the only part of the journaling code which really needs to be | |
419 | * aware of transaction aborts. Checkpointing involves writing to the | |
420 | * main filesystem area rather than to the journal, so it can proceed | |
421 | * even in abort state, but we must not update the journal superblock if | |
422 | * we have an abort error outstanding. | |
423 | */ | |
424 | ||
f7f4bccb | 425 | int jbd2_cleanup_journal_tail(journal_t *journal) |
470decc6 DK |
426 | { |
427 | transaction_t * transaction; | |
428 | tid_t first_tid; | |
429 | unsigned long blocknr, freed; | |
430 | ||
431 | /* OK, work out the oldest transaction remaining in the log, and | |
432 | * the log block it starts at. | |
433 | * | |
434 | * If the log is now empty, we need to work out which is the | |
435 | * next transaction ID we will write, and where it will | |
436 | * start. */ | |
437 | ||
438 | spin_lock(&journal->j_state_lock); | |
439 | spin_lock(&journal->j_list_lock); | |
440 | transaction = journal->j_checkpoint_transactions; | |
441 | if (transaction) { | |
442 | first_tid = transaction->t_tid; | |
443 | blocknr = transaction->t_log_start; | |
444 | } else if ((transaction = journal->j_committing_transaction) != NULL) { | |
445 | first_tid = transaction->t_tid; | |
446 | blocknr = transaction->t_log_start; | |
447 | } else if ((transaction = journal->j_running_transaction) != NULL) { | |
448 | first_tid = transaction->t_tid; | |
449 | blocknr = journal->j_head; | |
450 | } else { | |
451 | first_tid = journal->j_transaction_sequence; | |
452 | blocknr = journal->j_head; | |
453 | } | |
454 | spin_unlock(&journal->j_list_lock); | |
455 | J_ASSERT(blocknr != 0); | |
456 | ||
457 | /* If the oldest pinned transaction is at the tail of the log | |
458 | already then there's not much we can do right now. */ | |
459 | if (journal->j_tail_sequence == first_tid) { | |
460 | spin_unlock(&journal->j_state_lock); | |
461 | return 1; | |
462 | } | |
463 | ||
464 | /* OK, update the superblock to recover the freed space. | |
465 | * Physical blocks come first: have we wrapped beyond the end of | |
466 | * the log? */ | |
467 | freed = blocknr - journal->j_tail; | |
468 | if (blocknr < journal->j_tail) | |
469 | freed = freed + journal->j_last - journal->j_first; | |
470 | ||
471 | jbd_debug(1, | |
472 | "Cleaning journal tail from %d to %d (offset %lu), " | |
473 | "freeing %lu\n", | |
474 | journal->j_tail_sequence, first_tid, blocknr, freed); | |
475 | ||
476 | journal->j_free += freed; | |
477 | journal->j_tail_sequence = first_tid; | |
478 | journal->j_tail = blocknr; | |
479 | spin_unlock(&journal->j_state_lock); | |
f7f4bccb MC |
480 | if (!(journal->j_flags & JBD2_ABORT)) |
481 | jbd2_journal_update_superblock(journal, 1); | |
470decc6 DK |
482 | return 0; |
483 | } | |
484 | ||
485 | ||
486 | /* Checkpoint list management */ | |
487 | ||
488 | /* | |
489 | * journal_clean_one_cp_list | |
490 | * | |
491 | * Find all the written-back checkpoint buffers in the given list and release them. | |
492 | * | |
493 | * Called with the journal locked. | |
494 | * Called with j_list_lock held. | |
495 | * Returns number of bufers reaped (for debug) | |
496 | */ | |
497 | ||
498 | static int journal_clean_one_cp_list(struct journal_head *jh, int *released) | |
499 | { | |
500 | struct journal_head *last_jh; | |
501 | struct journal_head *next_jh = jh; | |
502 | int ret, freed = 0; | |
503 | ||
504 | *released = 0; | |
505 | if (!jh) | |
506 | return 0; | |
507 | ||
508 | last_jh = jh->b_cpprev; | |
509 | do { | |
510 | jh = next_jh; | |
511 | next_jh = jh->b_cpnext; | |
512 | /* Use trylock because of the ranking */ | |
513 | if (jbd_trylock_bh_state(jh2bh(jh))) { | |
514 | ret = __try_to_free_cp_buf(jh); | |
515 | if (ret) { | |
516 | freed++; | |
517 | if (ret == 2) { | |
518 | *released = 1; | |
519 | return freed; | |
520 | } | |
521 | } | |
522 | } | |
523 | /* | |
524 | * This function only frees up some memory | |
525 | * if possible so we dont have an obligation | |
526 | * to finish processing. Bail out if preemption | |
527 | * requested: | |
528 | */ | |
529 | if (need_resched()) | |
530 | return freed; | |
531 | } while (jh != last_jh); | |
532 | ||
533 | return freed; | |
534 | } | |
535 | ||
536 | /* | |
537 | * journal_clean_checkpoint_list | |
538 | * | |
539 | * Find all the written-back checkpoint buffers in the journal and release them. | |
540 | * | |
541 | * Called with the journal locked. | |
542 | * Called with j_list_lock held. | |
543 | * Returns number of buffers reaped (for debug) | |
544 | */ | |
545 | ||
f7f4bccb | 546 | int __jbd2_journal_clean_checkpoint_list(journal_t *journal) |
470decc6 DK |
547 | { |
548 | transaction_t *transaction, *last_transaction, *next_transaction; | |
549 | int ret = 0; | |
550 | int released; | |
551 | ||
552 | transaction = journal->j_checkpoint_transactions; | |
553 | if (!transaction) | |
554 | goto out; | |
555 | ||
556 | last_transaction = transaction->t_cpprev; | |
557 | next_transaction = transaction; | |
558 | do { | |
559 | transaction = next_transaction; | |
560 | next_transaction = transaction->t_cpnext; | |
561 | ret += journal_clean_one_cp_list(transaction-> | |
562 | t_checkpoint_list, &released); | |
563 | /* | |
564 | * This function only frees up some memory if possible so we | |
565 | * dont have an obligation to finish processing. Bail out if | |
566 | * preemption requested: | |
567 | */ | |
568 | if (need_resched()) | |
569 | goto out; | |
570 | if (released) | |
571 | continue; | |
572 | /* | |
573 | * It is essential that we are as careful as in the case of | |
574 | * t_checkpoint_list with removing the buffer from the list as | |
575 | * we can possibly see not yet submitted buffers on io_list | |
576 | */ | |
577 | ret += journal_clean_one_cp_list(transaction-> | |
578 | t_checkpoint_io_list, &released); | |
579 | if (need_resched()) | |
580 | goto out; | |
581 | } while (transaction != last_transaction); | |
582 | out: | |
583 | return ret; | |
584 | } | |
585 | ||
586 | /* | |
587 | * journal_remove_checkpoint: called after a buffer has been committed | |
588 | * to disk (either by being write-back flushed to disk, or being | |
589 | * committed to the log). | |
590 | * | |
591 | * We cannot safely clean a transaction out of the log until all of the | |
592 | * buffer updates committed in that transaction have safely been stored | |
593 | * elsewhere on disk. To achieve this, all of the buffers in a | |
594 | * transaction need to be maintained on the transaction's checkpoint | |
595 | * lists until they have been rewritten, at which point this function is | |
596 | * called to remove the buffer from the existing transaction's | |
597 | * checkpoint lists. | |
598 | * | |
599 | * The function returns 1 if it frees the transaction, 0 otherwise. | |
600 | * | |
601 | * This function is called with the journal locked. | |
602 | * This function is called with j_list_lock held. | |
603 | * This function is called with jbd_lock_bh_state(jh2bh(jh)) | |
604 | */ | |
605 | ||
f7f4bccb | 606 | int __jbd2_journal_remove_checkpoint(struct journal_head *jh) |
470decc6 DK |
607 | { |
608 | transaction_t *transaction; | |
609 | journal_t *journal; | |
610 | int ret = 0; | |
611 | ||
612 | JBUFFER_TRACE(jh, "entry"); | |
613 | ||
614 | if ((transaction = jh->b_cp_transaction) == NULL) { | |
615 | JBUFFER_TRACE(jh, "not on transaction"); | |
616 | goto out; | |
617 | } | |
618 | journal = transaction->t_journal; | |
619 | ||
620 | __buffer_unlink(jh); | |
621 | jh->b_cp_transaction = NULL; | |
622 | ||
623 | if (transaction->t_checkpoint_list != NULL || | |
624 | transaction->t_checkpoint_io_list != NULL) | |
625 | goto out; | |
626 | JBUFFER_TRACE(jh, "transaction has no more buffers"); | |
627 | ||
628 | /* | |
629 | * There is one special case to worry about: if we have just pulled the | |
f5a7a6b0 JK |
630 | * buffer off a running or committing transaction's checkpoing list, |
631 | * then even if the checkpoint list is empty, the transaction obviously | |
632 | * cannot be dropped! | |
470decc6 | 633 | * |
f5a7a6b0 | 634 | * The locking here around t_state is a bit sleazy. |
f7f4bccb | 635 | * See the comment at the end of jbd2_journal_commit_transaction(). |
470decc6 | 636 | */ |
f5a7a6b0 JK |
637 | if (transaction->t_state != T_FINISHED) { |
638 | JBUFFER_TRACE(jh, "belongs to running/committing transaction"); | |
470decc6 DK |
639 | goto out; |
640 | } | |
641 | ||
642 | /* OK, that was the last buffer for the transaction: we can now | |
643 | safely remove this transaction from the log */ | |
644 | ||
f7f4bccb | 645 | __jbd2_journal_drop_transaction(journal, transaction); |
470decc6 DK |
646 | |
647 | /* Just in case anybody was waiting for more transactions to be | |
648 | checkpointed... */ | |
649 | wake_up(&journal->j_wait_logspace); | |
650 | ret = 1; | |
651 | out: | |
652 | JBUFFER_TRACE(jh, "exit"); | |
653 | return ret; | |
654 | } | |
655 | ||
656 | /* | |
657 | * journal_insert_checkpoint: put a committed buffer onto a checkpoint | |
658 | * list so that we know when it is safe to clean the transaction out of | |
659 | * the log. | |
660 | * | |
661 | * Called with the journal locked. | |
662 | * Called with j_list_lock held. | |
663 | */ | |
f7f4bccb | 664 | void __jbd2_journal_insert_checkpoint(struct journal_head *jh, |
470decc6 DK |
665 | transaction_t *transaction) |
666 | { | |
667 | JBUFFER_TRACE(jh, "entry"); | |
668 | J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh))); | |
669 | J_ASSERT_JH(jh, jh->b_cp_transaction == NULL); | |
670 | ||
671 | jh->b_cp_transaction = transaction; | |
672 | ||
673 | if (!transaction->t_checkpoint_list) { | |
674 | jh->b_cpnext = jh->b_cpprev = jh; | |
675 | } else { | |
676 | jh->b_cpnext = transaction->t_checkpoint_list; | |
677 | jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev; | |
678 | jh->b_cpprev->b_cpnext = jh; | |
679 | jh->b_cpnext->b_cpprev = jh; | |
680 | } | |
681 | transaction->t_checkpoint_list = jh; | |
682 | } | |
683 | ||
684 | /* | |
685 | * We've finished with this transaction structure: adios... | |
686 | * | |
687 | * The transaction must have no links except for the checkpoint by this | |
688 | * point. | |
689 | * | |
690 | * Called with the journal locked. | |
691 | * Called with j_list_lock held. | |
692 | */ | |
693 | ||
f7f4bccb | 694 | void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction) |
470decc6 DK |
695 | { |
696 | assert_spin_locked(&journal->j_list_lock); | |
697 | if (transaction->t_cpnext) { | |
698 | transaction->t_cpnext->t_cpprev = transaction->t_cpprev; | |
699 | transaction->t_cpprev->t_cpnext = transaction->t_cpnext; | |
700 | if (journal->j_checkpoint_transactions == transaction) | |
701 | journal->j_checkpoint_transactions = | |
702 | transaction->t_cpnext; | |
703 | if (journal->j_checkpoint_transactions == transaction) | |
704 | journal->j_checkpoint_transactions = NULL; | |
705 | } | |
706 | ||
707 | J_ASSERT(transaction->t_state == T_FINISHED); | |
708 | J_ASSERT(transaction->t_buffers == NULL); | |
470decc6 DK |
709 | J_ASSERT(transaction->t_forget == NULL); |
710 | J_ASSERT(transaction->t_iobuf_list == NULL); | |
711 | J_ASSERT(transaction->t_shadow_list == NULL); | |
712 | J_ASSERT(transaction->t_log_list == NULL); | |
713 | J_ASSERT(transaction->t_checkpoint_list == NULL); | |
714 | J_ASSERT(transaction->t_checkpoint_io_list == NULL); | |
715 | J_ASSERT(transaction->t_updates == 0); | |
716 | J_ASSERT(journal->j_committing_transaction != transaction); | |
717 | J_ASSERT(journal->j_running_transaction != transaction); | |
718 | ||
719 | jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid); | |
720 | kfree(transaction); | |
721 | } |