Branch data Line data Source code
1 : : /*
2 : : * linux/fs/jbd/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/jbd.h>
23 : : #include <linux/errno.h>
24 : : #include <linux/slab.h>
25 : : #include <linux/blkdev.h>
26 : : #include <trace/events/jbd.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 : 0 : jh->b_cpnext->b_cpprev = jh->b_cpprev;
38 : 0 : jh->b_cpprev->b_cpnext = jh->b_cpnext;
39 [ # # # # ]: 0 : if (transaction->t_checkpoint_list == jh) {
40 : 0 : transaction->t_checkpoint_list = jh->b_cpnext;
41 [ # # ][ # # ]: 0 : if (transaction->t_checkpoint_list == jh)
42 : 0 : 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 [ # # ]: 0 : if (transaction->t_checkpoint_io_list == jh) {
57 : 0 : transaction->t_checkpoint_io_list = jh->b_cpnext;
58 [ # # ]: 0 : if (transaction->t_checkpoint_io_list == jh)
59 : 0 : 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 : 0 : transaction_t *transaction = jh->b_cp_transaction;
71 : :
72 : : __buffer_unlink_first(jh);
73 : :
74 [ # # ]: 0 : if (!transaction->t_checkpoint_io_list) {
75 : 0 : jh->b_cpnext = jh->b_cpprev = jh;
76 : : } else {
77 : 0 : jh->b_cpnext = transaction->t_checkpoint_io_list;
78 : 0 : jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
79 : 0 : jh->b_cpprev->b_cpnext = jh;
80 : 0 : jh->b_cpnext->b_cpprev = jh;
81 : : }
82 : 0 : 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 : 0 : 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 [ # # ][ # # ]: 0 : if (jh->b_jlist == BJ_None && !buffer_locked(bh) &&
[ # # ]
99 [ # # ]: 0 : !buffer_dirty(bh) && !buffer_write_io_error(bh)) {
100 : : /*
101 : : * Get our reference so that bh cannot be freed before
102 : : * we unlock it
103 : : */
104 : : get_bh(bh);
105 : : JBUFFER_TRACE(jh, "remove from checkpoint list");
106 : 0 : ret = __journal_remove_checkpoint(jh) + 1;
107 : : jbd_unlock_bh_state(bh);
108 : : BUFFER_TRACE(bh, "release");
109 : 0 : __brelse(bh);
110 : : } else {
111 : : jbd_unlock_bh_state(bh);
112 : : }
113 : 0 : return ret;
114 : : }
115 : :
116 : : /*
117 : : * __log_wait_for_space: wait until there is space in the journal.
118 : : *
119 : : * Called under j-state_lock *only*. It will be unlocked if we have to wait
120 : : * for a checkpoint to free up some space in the log.
121 : : */
122 : 0 : void __log_wait_for_space(journal_t *journal)
123 : : {
124 : : int nblocks, space_left;
125 [ # # ]: 0 : assert_spin_locked(&journal->j_state_lock);
126 : :
127 : : nblocks = jbd_space_needed(journal);
128 [ # # ]: 0 : while (__log_space_left(journal) < nblocks) {
129 [ # # ]: 0 : if (journal->j_flags & JFS_ABORT)
130 : 0 : return;
131 : : spin_unlock(&journal->j_state_lock);
132 : 0 : mutex_lock(&journal->j_checkpoint_mutex);
133 : :
134 : : /*
135 : : * Test again, another process may have checkpointed while we
136 : : * were waiting for the checkpoint lock. If there are no
137 : : * transactions ready to be checkpointed, try to recover
138 : : * journal space by calling cleanup_journal_tail(), and if
139 : : * that doesn't work, by waiting for the currently committing
140 : : * transaction to complete. If there is absolutely no way
141 : : * to make progress, this is either a BUG or corrupted
142 : : * filesystem, so abort the journal and leave a stack
143 : : * trace for forensic evidence.
144 : : */
145 : : spin_lock(&journal->j_state_lock);
146 : : spin_lock(&journal->j_list_lock);
147 : : nblocks = jbd_space_needed(journal);
148 : 0 : space_left = __log_space_left(journal);
149 [ # # ]: 0 : if (space_left < nblocks) {
150 : 0 : int chkpt = journal->j_checkpoint_transactions != NULL;
151 : : tid_t tid = 0;
152 : :
153 [ # # ]: 0 : if (journal->j_committing_transaction)
154 : 0 : tid = journal->j_committing_transaction->t_tid;
155 : : spin_unlock(&journal->j_list_lock);
156 : : spin_unlock(&journal->j_state_lock);
157 [ # # ]: 0 : if (chkpt) {
158 : 0 : log_do_checkpoint(journal);
159 [ # # ]: 0 : } else if (cleanup_journal_tail(journal) == 0) {
160 : : /* We were able to recover space; yay! */
161 : : ;
162 [ # # ]: 0 : } else if (tid) {
163 : 0 : log_wait_commit(journal, tid);
164 : : } else {
165 : 0 : printk(KERN_ERR "%s: needed %d blocks and "
166 : : "only had %d space available\n",
167 : : __func__, nblocks, space_left);
168 : 0 : printk(KERN_ERR "%s: no way to get more "
169 : : "journal space\n", __func__);
170 : 0 : WARN_ON(1);
171 : 0 : journal_abort(journal, 0);
172 : : }
173 : : spin_lock(&journal->j_state_lock);
174 : : } else {
175 : : spin_unlock(&journal->j_list_lock);
176 : : }
177 : 0 : mutex_unlock(&journal->j_checkpoint_mutex);
178 : : }
179 : : }
180 : :
181 : : /*
182 : : * We were unable to perform jbd_trylock_bh_state() inside j_list_lock.
183 : : * The caller must restart a list walk. Wait for someone else to run
184 : : * jbd_unlock_bh_state().
185 : : */
186 : 0 : static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)
187 : : __releases(journal->j_list_lock)
188 : : {
189 : : get_bh(bh);
190 : : spin_unlock(&journal->j_list_lock);
191 : : jbd_lock_bh_state(bh);
192 : : jbd_unlock_bh_state(bh);
193 : : put_bh(bh);
194 : 0 : }
195 : :
196 : : /*
197 : : * Clean up transaction's list of buffers submitted for io.
198 : : * We wait for any pending IO to complete and remove any clean
199 : : * buffers. Note that we take the buffers in the opposite ordering
200 : : * from the one in which they were submitted for IO.
201 : : *
202 : : * Return 0 on success, and return <0 if some buffers have failed
203 : : * to be written out.
204 : : *
205 : : * Called with j_list_lock held.
206 : : */
207 : 0 : static int __wait_cp_io(journal_t *journal, transaction_t *transaction)
208 : : {
209 : 0 : struct journal_head *jh;
210 : : struct buffer_head *bh;
211 : : tid_t this_tid;
212 : : int released = 0;
213 : : int ret = 0;
214 : :
215 : 0 : this_tid = transaction->t_tid;
216 : : restart:
217 : : /* Did somebody clean up the transaction in the meanwhile? */
218 [ # # ][ # # ]: 0 : if (journal->j_checkpoint_transactions != transaction ||
219 : 0 : transaction->t_tid != this_tid)
220 : : return ret;
221 [ # # ][ # # ]: 0 : while (!released && transaction->t_checkpoint_io_list) {
222 : : jh = transaction->t_checkpoint_io_list;
223 : : bh = jh2bh(jh);
224 [ # # ]: 0 : if (!jbd_trylock_bh_state(bh)) {
225 : 0 : jbd_sync_bh(journal, bh);
226 : : spin_lock(&journal->j_list_lock);
227 : : goto restart;
228 : : }
229 : : get_bh(bh);
230 [ # # ]: 0 : if (buffer_locked(bh)) {
231 : : spin_unlock(&journal->j_list_lock);
232 : : jbd_unlock_bh_state(bh);
233 : : wait_on_buffer(bh);
234 : : /* the journal_head may have gone by now */
235 : : BUFFER_TRACE(bh, "brelse");
236 : 0 : __brelse(bh);
237 : : spin_lock(&journal->j_list_lock);
238 : : goto restart;
239 : : }
240 [ # # ]: 0 : if (unlikely(buffer_write_io_error(bh)))
241 : : ret = -EIO;
242 : :
243 : : /*
244 : : * Now in whatever state the buffer currently is, we know that
245 : : * it has been written out and so we can drop it from the list
246 : : */
247 : 0 : released = __journal_remove_checkpoint(jh);
248 : : jbd_unlock_bh_state(bh);
249 : 0 : __brelse(bh);
250 : : }
251 : :
252 : : return ret;
253 : : }
254 : :
255 : : #define NR_BATCH 64
256 : :
257 : : static void
258 : 0 : __flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count)
259 : : {
260 : : int i;
261 : : struct blk_plug plug;
262 : :
263 : 0 : blk_start_plug(&plug);
264 [ # # ]: 0 : for (i = 0; i < *batch_count; i++)
265 : 0 : write_dirty_buffer(bhs[i], WRITE_SYNC);
266 : 0 : blk_finish_plug(&plug);
267 : :
268 [ # # ]: 0 : for (i = 0; i < *batch_count; i++) {
269 : 0 : struct buffer_head *bh = bhs[i];
270 : : clear_buffer_jwrite(bh);
271 : : BUFFER_TRACE(bh, "brelse");
272 : 0 : __brelse(bh);
273 : : }
274 : 0 : *batch_count = 0;
275 : 0 : }
276 : :
277 : : /*
278 : : * Try to flush one buffer from the checkpoint list to disk.
279 : : *
280 : : * Return 1 if something happened which requires us to abort the current
281 : : * scan of the checkpoint list. Return <0 if the buffer has failed to
282 : : * be written out.
283 : : *
284 : : * Called with j_list_lock held and drops it if 1 is returned
285 : : * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
286 : : */
287 : 0 : static int __process_buffer(journal_t *journal, struct journal_head *jh,
288 : : struct buffer_head **bhs, int *batch_count)
289 : : {
290 : : struct buffer_head *bh = jh2bh(jh);
291 : : int ret = 0;
292 : :
293 [ # # ]: 0 : if (buffer_locked(bh)) {
294 : : get_bh(bh);
295 : : spin_unlock(&journal->j_list_lock);
296 : : jbd_unlock_bh_state(bh);
297 : : wait_on_buffer(bh);
298 : : /* the journal_head may have gone by now */
299 : : BUFFER_TRACE(bh, "brelse");
300 : 0 : __brelse(bh);
301 : : ret = 1;
302 [ # # ]: 0 : } else if (jh->b_transaction != NULL) {
303 : : transaction_t *t = jh->b_transaction;
304 : 0 : tid_t tid = t->t_tid;
305 : :
306 : : spin_unlock(&journal->j_list_lock);
307 : : jbd_unlock_bh_state(bh);
308 : 0 : log_start_commit(journal, tid);
309 : 0 : log_wait_commit(journal, tid);
310 : : ret = 1;
311 [ # # ]: 0 : } else if (!buffer_dirty(bh)) {
312 : : ret = 1;
313 [ # # ]: 0 : if (unlikely(buffer_write_io_error(bh)))
314 : : ret = -EIO;
315 : : get_bh(bh);
316 [ # # ]: 0 : J_ASSERT_JH(jh, !buffer_jbddirty(bh));
317 : : BUFFER_TRACE(bh, "remove from checkpoint");
318 : 0 : __journal_remove_checkpoint(jh);
319 : : spin_unlock(&journal->j_list_lock);
320 : : jbd_unlock_bh_state(bh);
321 : 0 : __brelse(bh);
322 : : } else {
323 : : /*
324 : : * Important: we are about to write the buffer, and
325 : : * possibly block, while still holding the journal lock.
326 : : * We cannot afford to let the transaction logic start
327 : : * messing around with this buffer before we write it to
328 : : * disk, as that would break recoverability.
329 : : */
330 : : BUFFER_TRACE(bh, "queue");
331 : : get_bh(bh);
332 [ # # ]: 0 : J_ASSERT_BH(bh, !buffer_jwrite(bh));
333 : : set_buffer_jwrite(bh);
334 : 0 : bhs[*batch_count] = bh;
335 : : __buffer_relink_io(jh);
336 : : jbd_unlock_bh_state(bh);
337 : 0 : (*batch_count)++;
338 [ # # ]: 0 : if (*batch_count == NR_BATCH) {
339 : : spin_unlock(&journal->j_list_lock);
340 : 0 : __flush_batch(journal, bhs, batch_count);
341 : : ret = 1;
342 : : }
343 : : }
344 : 0 : return ret;
345 : : }
346 : :
347 : : /*
348 : : * Perform an actual checkpoint. We take the first transaction on the
349 : : * list of transactions to be checkpointed and send all its buffers
350 : : * to disk. We submit larger chunks of data at once.
351 : : *
352 : : * The journal should be locked before calling this function.
353 : : * Called with j_checkpoint_mutex held.
354 : : */
355 : 0 : int log_do_checkpoint(journal_t *journal)
356 : : {
357 : : transaction_t *transaction;
358 : : tid_t this_tid;
359 : : int result;
360 : :
361 : : jbd_debug(1, "Start checkpoint\n");
362 : :
363 : : /*
364 : : * First thing: if there are any transactions in the log which
365 : : * don't need checkpointing, just eliminate them from the
366 : : * journal straight away.
367 : : */
368 : 0 : result = cleanup_journal_tail(journal);
369 : : trace_jbd_checkpoint(journal, result);
370 : : jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
371 [ # # ]: 0 : if (result <= 0)
372 : : return result;
373 : :
374 : : /*
375 : : * OK, we need to start writing disk blocks. Take one transaction
376 : : * and write it.
377 : : */
378 : : result = 0;
379 : : spin_lock(&journal->j_list_lock);
380 [ # # ]: 0 : if (!journal->j_checkpoint_transactions)
381 : : goto out;
382 : : transaction = journal->j_checkpoint_transactions;
383 : 0 : this_tid = transaction->t_tid;
384 : : restart:
385 : : /*
386 : : * If someone cleaned up this transaction while we slept, we're
387 : : * done (maybe it's a new transaction, but it fell at the same
388 : : * address).
389 : : */
390 [ # # ][ # # ]: 0 : if (journal->j_checkpoint_transactions == transaction &&
391 : 0 : transaction->t_tid == this_tid) {
392 : 0 : int batch_count = 0;
393 : : struct buffer_head *bhs[NR_BATCH];
394 : 0 : struct journal_head *jh;
395 : : int retry = 0, err;
396 : :
397 [ # # ][ # # ]: 0 : while (!retry && transaction->t_checkpoint_list) {
398 : : struct buffer_head *bh;
399 : :
400 : : jh = transaction->t_checkpoint_list;
401 : : bh = jh2bh(jh);
402 [ # # ]: 0 : if (!jbd_trylock_bh_state(bh)) {
403 : 0 : jbd_sync_bh(journal, bh);
404 : : retry = 1;
405 : 0 : break;
406 : : }
407 : 0 : retry = __process_buffer(journal, jh, bhs,&batch_count);
408 [ # # ]: 0 : if (retry < 0 && !result)
409 : : result = retry;
410 [ # # ][ # # ]: 0 : if (!retry && (need_resched() ||
411 : : spin_needbreak(&journal->j_list_lock))) {
412 : : spin_unlock(&journal->j_list_lock);
413 : : retry = 1;
414 : 0 : break;
415 : : }
416 : : }
417 : :
418 [ # # ]: 0 : if (batch_count) {
419 [ # # ]: 0 : if (!retry) {
420 : : spin_unlock(&journal->j_list_lock);
421 : : retry = 1;
422 : : }
423 : 0 : __flush_batch(journal, bhs, &batch_count);
424 : : }
425 : :
426 [ # # ]: 0 : if (retry) {
427 : : spin_lock(&journal->j_list_lock);
428 : 0 : goto restart;
429 : : }
430 : : /*
431 : : * Now we have cleaned up the first transaction's checkpoint
432 : : * list. Let's clean up the second one
433 : : */
434 : 0 : err = __wait_cp_io(journal, transaction);
435 [ # # ]: 0 : if (!result)
436 : : result = err;
437 : : }
438 : : out:
439 : : spin_unlock(&journal->j_list_lock);
440 [ # # ]: 0 : if (result < 0)
441 : 0 : journal_abort(journal, result);
442 : : else
443 : 0 : result = cleanup_journal_tail(journal);
444 : :
445 : 0 : return (result < 0) ? result : 0;
446 : : }
447 : :
448 : : /*
449 : : * Check the list of checkpoint transactions for the journal to see if
450 : : * we have already got rid of any since the last update of the log tail
451 : : * in the journal superblock. If so, we can instantly roll the
452 : : * superblock forward to remove those transactions from the log.
453 : : *
454 : : * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
455 : : *
456 : : * This is the only part of the journaling code which really needs to be
457 : : * aware of transaction aborts. Checkpointing involves writing to the
458 : : * main filesystem area rather than to the journal, so it can proceed
459 : : * even in abort state, but we must not update the super block if
460 : : * checkpointing may have failed. Otherwise, we would lose some metadata
461 : : * buffers which should be written-back to the filesystem.
462 : : */
463 : :
464 : 0 : int cleanup_journal_tail(journal_t *journal)
465 : : {
466 : : transaction_t * transaction;
467 : : tid_t first_tid;
468 : : unsigned int blocknr, freed;
469 : :
470 [ # # ]: 0 : if (is_journal_aborted(journal))
471 : : return 1;
472 : :
473 : : /*
474 : : * OK, work out the oldest transaction remaining in the log, and
475 : : * the log block it starts at.
476 : : *
477 : : * If the log is now empty, we need to work out which is the
478 : : * next transaction ID we will write, and where it will
479 : : * start.
480 : : */
481 : : spin_lock(&journal->j_state_lock);
482 : : spin_lock(&journal->j_list_lock);
483 : 0 : transaction = journal->j_checkpoint_transactions;
484 [ # # ]: 0 : if (transaction) {
485 : 0 : first_tid = transaction->t_tid;
486 : 0 : blocknr = transaction->t_log_start;
487 [ # # ]: 0 : } else if ((transaction = journal->j_committing_transaction) != NULL) {
488 : 0 : first_tid = transaction->t_tid;
489 : 0 : blocknr = transaction->t_log_start;
490 [ # # ]: 0 : } else if ((transaction = journal->j_running_transaction) != NULL) {
491 : 0 : first_tid = transaction->t_tid;
492 : 0 : blocknr = journal->j_head;
493 : : } else {
494 : 0 : first_tid = journal->j_transaction_sequence;
495 : 0 : blocknr = journal->j_head;
496 : : }
497 : : spin_unlock(&journal->j_list_lock);
498 [ # # ]: 0 : J_ASSERT(blocknr != 0);
499 : :
500 : : /* If the oldest pinned transaction is at the tail of the log
501 : : already then there's not much we can do right now. */
502 [ # # ]: 0 : if (journal->j_tail_sequence == first_tid) {
503 : : spin_unlock(&journal->j_state_lock);
504 : 0 : return 1;
505 : : }
506 : : spin_unlock(&journal->j_state_lock);
507 : :
508 : : /*
509 : : * We need to make sure that any blocks that were recently written out
510 : : * --- perhaps by log_do_checkpoint() --- are flushed out before we
511 : : * drop the transactions from the journal. Similarly we need to be sure
512 : : * superblock makes it to disk before next transaction starts reusing
513 : : * freed space (otherwise we could replay some blocks of the new
514 : : * transaction thinking they belong to the old one). So we use
515 : : * WRITE_FLUSH_FUA. It's unlikely this will be necessary, especially
516 : : * with an appropriately sized journal, but we need this to guarantee
517 : : * correctness. Fortunately cleanup_journal_tail() doesn't get called
518 : : * all that often.
519 : : */
520 : 0 : journal_update_sb_log_tail(journal, first_tid, blocknr,
521 : : WRITE_FLUSH_FUA);
522 : :
523 : : spin_lock(&journal->j_state_lock);
524 : : /* OK, update the superblock to recover the freed space.
525 : : * Physical blocks come first: have we wrapped beyond the end of
526 : : * the log? */
527 : 0 : freed = blocknr - journal->j_tail;
528 [ # # ]: 0 : if (blocknr < journal->j_tail)
529 : 0 : freed = freed + journal->j_last - journal->j_first;
530 : :
531 : : trace_jbd_cleanup_journal_tail(journal, first_tid, blocknr, freed);
532 : : jbd_debug(1,
533 : : "Cleaning journal tail from %d to %d (offset %u), "
534 : : "freeing %u\n",
535 : : journal->j_tail_sequence, first_tid, blocknr, freed);
536 : :
537 : 0 : journal->j_free += freed;
538 : 0 : journal->j_tail_sequence = first_tid;
539 : 0 : journal->j_tail = blocknr;
540 : : spin_unlock(&journal->j_state_lock);
541 : 0 : return 0;
542 : : }
543 : :
544 : :
545 : : /* Checkpoint list management */
546 : :
547 : : /*
548 : : * journal_clean_one_cp_list
549 : : *
550 : : * Find all the written-back checkpoint buffers in the given list and release
551 : : * them.
552 : : *
553 : : * Called with j_list_lock held.
554 : : * Returns number of buffers reaped (for debug)
555 : : */
556 : :
557 : 0 : static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
558 : : {
559 : : struct journal_head *last_jh;
560 : : struct journal_head *next_jh = jh;
561 : : int ret, freed = 0;
562 : :
563 : 0 : *released = 0;
564 [ # # ]: 0 : if (!jh)
565 : : return 0;
566 : :
567 : 0 : last_jh = jh->b_cpprev;
568 : : do {
569 : : jh = next_jh;
570 : 0 : next_jh = jh->b_cpnext;
571 : : /* Use trylock because of the ranking */
572 [ # # ]: 0 : if (jbd_trylock_bh_state(jh2bh(jh))) {
573 : 0 : ret = __try_to_free_cp_buf(jh);
574 [ # # ]: 0 : if (ret) {
575 : 0 : freed++;
576 [ # # ]: 0 : if (ret == 2) {
577 : 0 : *released = 1;
578 : 0 : return freed;
579 : : }
580 : : }
581 : : }
582 : : /*
583 : : * This function only frees up some memory
584 : : * if possible so we dont have an obligation
585 : : * to finish processing. Bail out if preemption
586 : : * requested:
587 : : */
588 [ # # ]: 0 : if (need_resched())
589 : : return freed;
590 [ # # ]: 0 : } while (jh != last_jh);
591 : :
592 : : return freed;
593 : : }
594 : :
595 : : /*
596 : : * journal_clean_checkpoint_list
597 : : *
598 : : * Find all the written-back checkpoint buffers in the journal and release them.
599 : : *
600 : : * Called with the journal locked.
601 : : * Called with j_list_lock held.
602 : : * Returns number of buffers reaped (for debug)
603 : : */
604 : :
605 : 0 : int __journal_clean_checkpoint_list(journal_t *journal)
606 : : {
607 : : transaction_t *transaction, *last_transaction, *next_transaction;
608 : : int ret = 0;
609 : : int released;
610 : :
611 : 0 : transaction = journal->j_checkpoint_transactions;
612 [ # # ]: 0 : if (!transaction)
613 : : goto out;
614 : :
615 : 0 : last_transaction = transaction->t_cpprev;
616 : : next_transaction = transaction;
617 : : do {
618 : : transaction = next_transaction;
619 : 0 : next_transaction = transaction->t_cpnext;
620 : 0 : ret += journal_clean_one_cp_list(transaction->
621 : : t_checkpoint_list, &released);
622 : : /*
623 : : * This function only frees up some memory if possible so we
624 : : * dont have an obligation to finish processing. Bail out if
625 : : * preemption requested:
626 : : */
627 [ # # ]: 0 : if (need_resched())
628 : : goto out;
629 [ # # ]: 0 : if (released)
630 : 0 : continue;
631 : : /*
632 : : * It is essential that we are as careful as in the case of
633 : : * t_checkpoint_list with removing the buffer from the list as
634 : : * we can possibly see not yet submitted buffers on io_list
635 : : */
636 : 0 : ret += journal_clean_one_cp_list(transaction->
637 : : t_checkpoint_io_list, &released);
638 [ # # ]: 0 : if (need_resched())
639 : : goto out;
640 [ # # ]: 0 : } while (transaction != last_transaction);
641 : : out:
642 : 0 : return ret;
643 : : }
644 : :
645 : : /*
646 : : * journal_remove_checkpoint: called after a buffer has been committed
647 : : * to disk (either by being write-back flushed to disk, or being
648 : : * committed to the log).
649 : : *
650 : : * We cannot safely clean a transaction out of the log until all of the
651 : : * buffer updates committed in that transaction have safely been stored
652 : : * elsewhere on disk. To achieve this, all of the buffers in a
653 : : * transaction need to be maintained on the transaction's checkpoint
654 : : * lists until they have been rewritten, at which point this function is
655 : : * called to remove the buffer from the existing transaction's
656 : : * checkpoint lists.
657 : : *
658 : : * The function returns 1 if it frees the transaction, 0 otherwise.
659 : : * The function can free jh and bh.
660 : : *
661 : : * This function is called with j_list_lock held.
662 : : * This function is called with jbd_lock_bh_state(jh2bh(jh))
663 : : */
664 : :
665 : 0 : int __journal_remove_checkpoint(struct journal_head *jh)
666 : : {
667 : : transaction_t *transaction;
668 : : journal_t *journal;
669 : : int ret = 0;
670 : :
671 : : JBUFFER_TRACE(jh, "entry");
672 : :
673 [ # # ]: 0 : if ((transaction = jh->b_cp_transaction) == NULL) {
674 : : JBUFFER_TRACE(jh, "not on transaction");
675 : : goto out;
676 : : }
677 : 0 : journal = transaction->t_journal;
678 : :
679 : : JBUFFER_TRACE(jh, "removing from transaction");
680 : : __buffer_unlink(jh);
681 : 0 : jh->b_cp_transaction = NULL;
682 : 0 : journal_put_journal_head(jh);
683 : :
684 [ # # ][ # # ]: 0 : if (transaction->t_checkpoint_list != NULL ||
685 : 0 : transaction->t_checkpoint_io_list != NULL)
686 : : goto out;
687 : :
688 : : /*
689 : : * There is one special case to worry about: if we have just pulled the
690 : : * buffer off a running or committing transaction's checkpoing list,
691 : : * then even if the checkpoint list is empty, the transaction obviously
692 : : * cannot be dropped!
693 : : *
694 : : * The locking here around t_state is a bit sleazy.
695 : : * See the comment at the end of journal_commit_transaction().
696 : : */
697 [ # # ]: 0 : if (transaction->t_state != T_FINISHED)
698 : : goto out;
699 : :
700 : : /* OK, that was the last buffer for the transaction: we can now
701 : : safely remove this transaction from the log */
702 : :
703 : 0 : __journal_drop_transaction(journal, transaction);
704 : :
705 : : /* Just in case anybody was waiting for more transactions to be
706 : : checkpointed... */
707 : 0 : wake_up(&journal->j_wait_logspace);
708 : : ret = 1;
709 : : out:
710 : 0 : return ret;
711 : : }
712 : :
713 : : /*
714 : : * journal_insert_checkpoint: put a committed buffer onto a checkpoint
715 : : * list so that we know when it is safe to clean the transaction out of
716 : : * the log.
717 : : *
718 : : * Called with the journal locked.
719 : : * Called with j_list_lock held.
720 : : */
721 : 0 : void __journal_insert_checkpoint(struct journal_head *jh,
722 : : transaction_t *transaction)
723 : : {
724 : : JBUFFER_TRACE(jh, "entry");
725 [ # # ][ # # ]: 0 : J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
726 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
727 : :
728 : : /* Get reference for checkpointing transaction */
729 : 0 : journal_grab_journal_head(jh2bh(jh));
730 : 0 : jh->b_cp_transaction = transaction;
731 : :
732 [ # # ]: 0 : if (!transaction->t_checkpoint_list) {
733 : 0 : jh->b_cpnext = jh->b_cpprev = jh;
734 : : } else {
735 : 0 : jh->b_cpnext = transaction->t_checkpoint_list;
736 : 0 : jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
737 : 0 : jh->b_cpprev->b_cpnext = jh;
738 : 0 : jh->b_cpnext->b_cpprev = jh;
739 : : }
740 : 0 : transaction->t_checkpoint_list = jh;
741 : 0 : }
742 : :
743 : : /*
744 : : * We've finished with this transaction structure: adios...
745 : : *
746 : : * The transaction must have no links except for the checkpoint by this
747 : : * point.
748 : : *
749 : : * Called with the journal locked.
750 : : * Called with j_list_lock held.
751 : : */
752 : :
753 : 0 : void __journal_drop_transaction(journal_t *journal, transaction_t *transaction)
754 : : {
755 [ # # ]: 0 : assert_spin_locked(&journal->j_list_lock);
756 [ # # ]: 0 : if (transaction->t_cpnext) {
757 : 0 : transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
758 : 0 : transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
759 [ # # ]: 0 : if (journal->j_checkpoint_transactions == transaction)
760 : 0 : journal->j_checkpoint_transactions =
761 : 0 : transaction->t_cpnext;
762 [ # # ]: 0 : if (journal->j_checkpoint_transactions == transaction)
763 : 0 : journal->j_checkpoint_transactions = NULL;
764 : : }
765 : :
766 [ # # ]: 0 : J_ASSERT(transaction->t_state == T_FINISHED);
767 [ # # ]: 0 : J_ASSERT(transaction->t_buffers == NULL);
768 [ # # ]: 0 : J_ASSERT(transaction->t_sync_datalist == NULL);
769 [ # # ]: 0 : J_ASSERT(transaction->t_forget == NULL);
770 [ # # ]: 0 : J_ASSERT(transaction->t_iobuf_list == NULL);
771 [ # # ]: 0 : J_ASSERT(transaction->t_shadow_list == NULL);
772 [ # # ]: 0 : J_ASSERT(transaction->t_log_list == NULL);
773 [ # # ]: 0 : J_ASSERT(transaction->t_checkpoint_list == NULL);
774 [ # # ]: 0 : J_ASSERT(transaction->t_checkpoint_io_list == NULL);
775 [ # # ]: 0 : J_ASSERT(transaction->t_updates == 0);
776 [ # # ]: 0 : J_ASSERT(journal->j_committing_transaction != transaction);
777 [ # # ]: 0 : J_ASSERT(journal->j_running_transaction != transaction);
778 : :
779 : : trace_jbd_drop_transaction(journal, transaction);
780 : : jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
781 : 0 : kfree(transaction);
782 : 0 : }
|
