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 | ||
44519faf HK |
97 | if (jh->b_jlist == BJ_None && !buffer_locked(bh) && |
98 | !buffer_dirty(bh) && !buffer_write_io_error(bh)) { | |
470decc6 | 99 | JBUFFER_TRACE(jh, "remove from checkpoint list"); |
f7f4bccb | 100 | ret = __jbd2_journal_remove_checkpoint(jh) + 1; |
470decc6 | 101 | jbd_unlock_bh_state(bh); |
f7f4bccb | 102 | jbd2_journal_remove_journal_head(bh); |
470decc6 DK |
103 | BUFFER_TRACE(bh, "release"); |
104 | __brelse(bh); | |
105 | } else { | |
106 | jbd_unlock_bh_state(bh); | |
107 | } | |
108 | return ret; | |
109 | } | |
110 | ||
111 | /* | |
f7f4bccb | 112 | * __jbd2_log_wait_for_space: wait until there is space in the journal. |
470decc6 DK |
113 | * |
114 | * Called under j-state_lock *only*. It will be unlocked if we have to wait | |
115 | * for a checkpoint to free up some space in the log. | |
116 | */ | |
f7f4bccb | 117 | void __jbd2_log_wait_for_space(journal_t *journal) |
470decc6 DK |
118 | { |
119 | int nblocks; | |
120 | assert_spin_locked(&journal->j_state_lock); | |
121 | ||
122 | nblocks = jbd_space_needed(journal); | |
f7f4bccb MC |
123 | while (__jbd2_log_space_left(journal) < nblocks) { |
124 | if (journal->j_flags & JBD2_ABORT) | |
470decc6 DK |
125 | return; |
126 | spin_unlock(&journal->j_state_lock); | |
127 | mutex_lock(&journal->j_checkpoint_mutex); | |
128 | ||
129 | /* | |
130 | * Test again, another process may have checkpointed while we | |
23f8b79e DG |
131 | * were waiting for the checkpoint lock. If there are no |
132 | * outstanding transactions there is nothing to checkpoint and | |
133 | * we can't make progress. Abort the journal in this case. | |
470decc6 DK |
134 | */ |
135 | spin_lock(&journal->j_state_lock); | |
23f8b79e | 136 | spin_lock(&journal->j_list_lock); |
470decc6 | 137 | nblocks = jbd_space_needed(journal); |
f7f4bccb | 138 | if (__jbd2_log_space_left(journal) < nblocks) { |
23f8b79e DG |
139 | int chkpt = journal->j_checkpoint_transactions != NULL; |
140 | ||
141 | spin_unlock(&journal->j_list_lock); | |
470decc6 | 142 | spin_unlock(&journal->j_state_lock); |
23f8b79e DG |
143 | if (chkpt) { |
144 | jbd2_log_do_checkpoint(journal); | |
145 | } else { | |
146 | printk(KERN_ERR "%s: no transactions\n", | |
147 | __func__); | |
148 | jbd2_journal_abort(journal, 0); | |
149 | } | |
150 | ||
470decc6 | 151 | spin_lock(&journal->j_state_lock); |
23f8b79e DG |
152 | } else { |
153 | spin_unlock(&journal->j_list_lock); | |
470decc6 DK |
154 | } |
155 | mutex_unlock(&journal->j_checkpoint_mutex); | |
156 | } | |
157 | } | |
158 | ||
159 | /* | |
160 | * We were unable to perform jbd_trylock_bh_state() inside j_list_lock. | |
161 | * The caller must restart a list walk. Wait for someone else to run | |
162 | * jbd_unlock_bh_state(). | |
163 | */ | |
164 | static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh) | |
165 | __releases(journal->j_list_lock) | |
166 | { | |
167 | get_bh(bh); | |
168 | spin_unlock(&journal->j_list_lock); | |
169 | jbd_lock_bh_state(bh); | |
170 | jbd_unlock_bh_state(bh); | |
171 | put_bh(bh); | |
172 | } | |
173 | ||
174 | /* | |
175 | * Clean up transaction's list of buffers submitted for io. | |
176 | * We wait for any pending IO to complete and remove any clean | |
177 | * buffers. Note that we take the buffers in the opposite ordering | |
178 | * from the one in which they were submitted for IO. | |
179 | * | |
44519faf HK |
180 | * Return 0 on success, and return <0 if some buffers have failed |
181 | * to be written out. | |
182 | * | |
470decc6 DK |
183 | * Called with j_list_lock held. |
184 | */ | |
44519faf | 185 | static int __wait_cp_io(journal_t *journal, transaction_t *transaction) |
470decc6 DK |
186 | { |
187 | struct journal_head *jh; | |
188 | struct buffer_head *bh; | |
189 | tid_t this_tid; | |
190 | int released = 0; | |
44519faf | 191 | int ret = 0; |
470decc6 DK |
192 | |
193 | this_tid = transaction->t_tid; | |
194 | restart: | |
195 | /* Did somebody clean up the transaction in the meanwhile? */ | |
196 | if (journal->j_checkpoint_transactions != transaction || | |
197 | transaction->t_tid != this_tid) | |
44519faf | 198 | return ret; |
470decc6 DK |
199 | while (!released && transaction->t_checkpoint_io_list) { |
200 | jh = transaction->t_checkpoint_io_list; | |
201 | bh = jh2bh(jh); | |
202 | if (!jbd_trylock_bh_state(bh)) { | |
203 | jbd_sync_bh(journal, bh); | |
204 | spin_lock(&journal->j_list_lock); | |
205 | goto restart; | |
206 | } | |
207 | if (buffer_locked(bh)) { | |
208 | atomic_inc(&bh->b_count); | |
209 | spin_unlock(&journal->j_list_lock); | |
210 | jbd_unlock_bh_state(bh); | |
211 | wait_on_buffer(bh); | |
212 | /* the journal_head may have gone by now */ | |
213 | BUFFER_TRACE(bh, "brelse"); | |
214 | __brelse(bh); | |
215 | spin_lock(&journal->j_list_lock); | |
216 | goto restart; | |
217 | } | |
44519faf HK |
218 | if (unlikely(buffer_write_io_error(bh))) |
219 | ret = -EIO; | |
220 | ||
470decc6 DK |
221 | /* |
222 | * Now in whatever state the buffer currently is, we know that | |
223 | * it has been written out and so we can drop it from the list | |
224 | */ | |
f7f4bccb | 225 | released = __jbd2_journal_remove_checkpoint(jh); |
470decc6 | 226 | jbd_unlock_bh_state(bh); |
f7f4bccb | 227 | jbd2_journal_remove_journal_head(bh); |
470decc6 DK |
228 | __brelse(bh); |
229 | } | |
44519faf HK |
230 | |
231 | return ret; | |
470decc6 DK |
232 | } |
233 | ||
234 | #define NR_BATCH 64 | |
235 | ||
236 | static void | |
237 | __flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count) | |
238 | { | |
239 | int i; | |
240 | ||
241 | ll_rw_block(SWRITE, *batch_count, bhs); | |
242 | for (i = 0; i < *batch_count; i++) { | |
243 | struct buffer_head *bh = bhs[i]; | |
244 | clear_buffer_jwrite(bh); | |
245 | BUFFER_TRACE(bh, "brelse"); | |
246 | __brelse(bh); | |
247 | } | |
248 | *batch_count = 0; | |
249 | } | |
250 | ||
251 | /* | |
252 | * Try to flush one buffer from the checkpoint list to disk. | |
253 | * | |
254 | * Return 1 if something happened which requires us to abort the current | |
44519faf HK |
255 | * scan of the checkpoint list. Return <0 if the buffer has failed to |
256 | * be written out. | |
470decc6 DK |
257 | * |
258 | * Called with j_list_lock held and drops it if 1 is returned | |
259 | * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it | |
260 | */ | |
261 | static int __process_buffer(journal_t *journal, struct journal_head *jh, | |
8e85fb3f JL |
262 | struct buffer_head **bhs, int *batch_count, |
263 | transaction_t *transaction) | |
470decc6 DK |
264 | { |
265 | struct buffer_head *bh = jh2bh(jh); | |
266 | int ret = 0; | |
267 | ||
268 | if (buffer_locked(bh)) { | |
269 | atomic_inc(&bh->b_count); | |
270 | spin_unlock(&journal->j_list_lock); | |
271 | jbd_unlock_bh_state(bh); | |
272 | wait_on_buffer(bh); | |
273 | /* the journal_head may have gone by now */ | |
274 | BUFFER_TRACE(bh, "brelse"); | |
275 | __brelse(bh); | |
276 | ret = 1; | |
277 | } else if (jh->b_transaction != NULL) { | |
278 | transaction_t *t = jh->b_transaction; | |
279 | tid_t tid = t->t_tid; | |
280 | ||
8e85fb3f | 281 | transaction->t_chp_stats.cs_forced_to_close++; |
470decc6 DK |
282 | spin_unlock(&journal->j_list_lock); |
283 | jbd_unlock_bh_state(bh); | |
f7f4bccb MC |
284 | jbd2_log_start_commit(journal, tid); |
285 | jbd2_log_wait_commit(journal, tid); | |
470decc6 DK |
286 | ret = 1; |
287 | } else if (!buffer_dirty(bh)) { | |
44519faf HK |
288 | ret = 1; |
289 | if (unlikely(buffer_write_io_error(bh))) | |
290 | ret = -EIO; | |
470decc6 DK |
291 | J_ASSERT_JH(jh, !buffer_jbddirty(bh)); |
292 | BUFFER_TRACE(bh, "remove from checkpoint"); | |
f7f4bccb | 293 | __jbd2_journal_remove_checkpoint(jh); |
470decc6 DK |
294 | spin_unlock(&journal->j_list_lock); |
295 | jbd_unlock_bh_state(bh); | |
f7f4bccb | 296 | jbd2_journal_remove_journal_head(bh); |
470decc6 | 297 | __brelse(bh); |
470decc6 DK |
298 | } else { |
299 | /* | |
300 | * Important: we are about to write the buffer, and | |
301 | * possibly block, while still holding the journal lock. | |
302 | * We cannot afford to let the transaction logic start | |
303 | * messing around with this buffer before we write it to | |
304 | * disk, as that would break recoverability. | |
305 | */ | |
306 | BUFFER_TRACE(bh, "queue"); | |
307 | get_bh(bh); | |
308 | J_ASSERT_BH(bh, !buffer_jwrite(bh)); | |
309 | set_buffer_jwrite(bh); | |
310 | bhs[*batch_count] = bh; | |
311 | __buffer_relink_io(jh); | |
312 | jbd_unlock_bh_state(bh); | |
8e85fb3f | 313 | transaction->t_chp_stats.cs_written++; |
470decc6 DK |
314 | (*batch_count)++; |
315 | if (*batch_count == NR_BATCH) { | |
316 | spin_unlock(&journal->j_list_lock); | |
317 | __flush_batch(journal, bhs, 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. | |
44519faf | 330 | * Called with j_checkpoint_mutex held. |
470decc6 | 331 | */ |
f7f4bccb | 332 | int jbd2_log_do_checkpoint(journal_t *journal) |
470decc6 DK |
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 | */ | |
f7f4bccb | 345 | result = jbd2_cleanup_journal_tail(journal); |
ede86cc4 TT |
346 | trace_mark(jbd2_checkpoint, "dev %s need_checkpoint %d", |
347 | journal->j_devname, result); | |
470decc6 DK |
348 | jbd_debug(1, "cleanup_journal_tail returned %d\n", result); |
349 | if (result <= 0) | |
350 | return result; | |
351 | ||
352 | /* | |
353 | * OK, we need to start writing disk blocks. Take one transaction | |
354 | * and write it. | |
355 | */ | |
44519faf | 356 | result = 0; |
470decc6 DK |
357 | spin_lock(&journal->j_list_lock); |
358 | if (!journal->j_checkpoint_transactions) | |
359 | goto out; | |
360 | transaction = journal->j_checkpoint_transactions; | |
8e85fb3f JL |
361 | if (transaction->t_chp_stats.cs_chp_time == 0) |
362 | transaction->t_chp_stats.cs_chp_time = jiffies; | |
470decc6 DK |
363 | this_tid = transaction->t_tid; |
364 | restart: | |
365 | /* | |
366 | * If someone cleaned up this transaction while we slept, we're | |
367 | * done (maybe it's a new transaction, but it fell at the same | |
368 | * address). | |
369 | */ | |
370 | if (journal->j_checkpoint_transactions == transaction && | |
371 | transaction->t_tid == this_tid) { | |
372 | int batch_count = 0; | |
373 | struct buffer_head *bhs[NR_BATCH]; | |
374 | struct journal_head *jh; | |
44519faf | 375 | int retry = 0, err; |
470decc6 DK |
376 | |
377 | while (!retry && transaction->t_checkpoint_list) { | |
378 | struct buffer_head *bh; | |
379 | ||
380 | jh = transaction->t_checkpoint_list; | |
381 | bh = jh2bh(jh); | |
382 | if (!jbd_trylock_bh_state(bh)) { | |
383 | jbd_sync_bh(journal, bh); | |
384 | retry = 1; | |
385 | break; | |
386 | } | |
8e85fb3f JL |
387 | retry = __process_buffer(journal, jh, bhs, &batch_count, |
388 | transaction); | |
44519faf HK |
389 | if (retry < 0 && !result) |
390 | result = retry; | |
95c354fe NP |
391 | if (!retry && (need_resched() || |
392 | spin_needbreak(&journal->j_list_lock))) { | |
470decc6 DK |
393 | spin_unlock(&journal->j_list_lock); |
394 | retry = 1; | |
395 | break; | |
396 | } | |
397 | } | |
398 | ||
399 | if (batch_count) { | |
400 | if (!retry) { | |
401 | spin_unlock(&journal->j_list_lock); | |
402 | retry = 1; | |
403 | } | |
404 | __flush_batch(journal, bhs, &batch_count); | |
405 | } | |
406 | ||
407 | if (retry) { | |
408 | spin_lock(&journal->j_list_lock); | |
409 | goto restart; | |
410 | } | |
411 | /* | |
412 | * Now we have cleaned up the first transaction's checkpoint | |
413 | * list. Let's clean up the second one | |
414 | */ | |
44519faf HK |
415 | err = __wait_cp_io(journal, transaction); |
416 | if (!result) | |
417 | result = err; | |
470decc6 DK |
418 | } |
419 | out: | |
420 | spin_unlock(&journal->j_list_lock); | |
470decc6 | 421 | if (result < 0) |
44519faf HK |
422 | jbd2_journal_abort(journal, result); |
423 | else | |
424 | result = jbd2_cleanup_journal_tail(journal); | |
425 | ||
426 | return (result < 0) ? result : 0; | |
470decc6 DK |
427 | } |
428 | ||
429 | /* | |
430 | * Check the list of checkpoint transactions for the journal to see if | |
431 | * we have already got rid of any since the last update of the log tail | |
432 | * in the journal superblock. If so, we can instantly roll the | |
433 | * superblock forward to remove those transactions from the log. | |
434 | * | |
435 | * Return <0 on error, 0 on success, 1 if there was nothing to clean up. | |
436 | * | |
437 | * Called with the journal lock held. | |
438 | * | |
439 | * This is the only part of the journaling code which really needs to be | |
440 | * aware of transaction aborts. Checkpointing involves writing to the | |
441 | * main filesystem area rather than to the journal, so it can proceed | |
44519faf HK |
442 | * even in abort state, but we must not update the super block if |
443 | * checkpointing may have failed. Otherwise, we would lose some metadata | |
444 | * buffers which should be written-back to the filesystem. | |
470decc6 DK |
445 | */ |
446 | ||
f7f4bccb | 447 | int jbd2_cleanup_journal_tail(journal_t *journal) |
470decc6 DK |
448 | { |
449 | transaction_t * transaction; | |
450 | tid_t first_tid; | |
451 | unsigned long blocknr, freed; | |
452 | ||
44519faf HK |
453 | if (is_journal_aborted(journal)) |
454 | return 1; | |
455 | ||
470decc6 DK |
456 | /* OK, work out the oldest transaction remaining in the log, and |
457 | * the log block it starts at. | |
458 | * | |
459 | * If the log is now empty, we need to work out which is the | |
460 | * next transaction ID we will write, and where it will | |
461 | * start. */ | |
462 | ||
463 | spin_lock(&journal->j_state_lock); | |
464 | spin_lock(&journal->j_list_lock); | |
465 | transaction = journal->j_checkpoint_transactions; | |
466 | if (transaction) { | |
467 | first_tid = transaction->t_tid; | |
468 | blocknr = transaction->t_log_start; | |
469 | } else if ((transaction = journal->j_committing_transaction) != NULL) { | |
470 | first_tid = transaction->t_tid; | |
471 | blocknr = transaction->t_log_start; | |
472 | } else if ((transaction = journal->j_running_transaction) != NULL) { | |
473 | first_tid = transaction->t_tid; | |
474 | blocknr = journal->j_head; | |
475 | } else { | |
476 | first_tid = journal->j_transaction_sequence; | |
477 | blocknr = journal->j_head; | |
478 | } | |
479 | spin_unlock(&journal->j_list_lock); | |
480 | J_ASSERT(blocknr != 0); | |
481 | ||
482 | /* If the oldest pinned transaction is at the tail of the log | |
483 | already then there's not much we can do right now. */ | |
484 | if (journal->j_tail_sequence == first_tid) { | |
485 | spin_unlock(&journal->j_state_lock); | |
486 | return 1; | |
487 | } | |
488 | ||
489 | /* OK, update the superblock to recover the freed space. | |
490 | * Physical blocks come first: have we wrapped beyond the end of | |
491 | * the log? */ | |
492 | freed = blocknr - journal->j_tail; | |
493 | if (blocknr < journal->j_tail) | |
494 | freed = freed + journal->j_last - journal->j_first; | |
495 | ||
496 | jbd_debug(1, | |
497 | "Cleaning journal tail from %d to %d (offset %lu), " | |
498 | "freeing %lu\n", | |
499 | journal->j_tail_sequence, first_tid, blocknr, freed); | |
500 | ||
501 | journal->j_free += freed; | |
502 | journal->j_tail_sequence = first_tid; | |
503 | journal->j_tail = blocknr; | |
504 | spin_unlock(&journal->j_state_lock); | |
f7f4bccb MC |
505 | if (!(journal->j_flags & JBD2_ABORT)) |
506 | jbd2_journal_update_superblock(journal, 1); | |
470decc6 DK |
507 | return 0; |
508 | } | |
509 | ||
510 | ||
511 | /* Checkpoint list management */ | |
512 | ||
513 | /* | |
514 | * journal_clean_one_cp_list | |
515 | * | |
516 | * Find all the written-back checkpoint buffers in the given list and release them. | |
517 | * | |
518 | * Called with the journal locked. | |
519 | * Called with j_list_lock held. | |
520 | * Returns number of bufers reaped (for debug) | |
521 | */ | |
522 | ||
523 | static int journal_clean_one_cp_list(struct journal_head *jh, int *released) | |
524 | { | |
525 | struct journal_head *last_jh; | |
526 | struct journal_head *next_jh = jh; | |
527 | int ret, freed = 0; | |
528 | ||
529 | *released = 0; | |
530 | if (!jh) | |
531 | return 0; | |
532 | ||
533 | last_jh = jh->b_cpprev; | |
534 | do { | |
535 | jh = next_jh; | |
536 | next_jh = jh->b_cpnext; | |
537 | /* Use trylock because of the ranking */ | |
538 | if (jbd_trylock_bh_state(jh2bh(jh))) { | |
539 | ret = __try_to_free_cp_buf(jh); | |
540 | if (ret) { | |
541 | freed++; | |
542 | if (ret == 2) { | |
543 | *released = 1; | |
544 | return freed; | |
545 | } | |
546 | } | |
547 | } | |
548 | /* | |
549 | * This function only frees up some memory | |
550 | * if possible so we dont have an obligation | |
551 | * to finish processing. Bail out if preemption | |
552 | * requested: | |
553 | */ | |
554 | if (need_resched()) | |
555 | return freed; | |
556 | } while (jh != last_jh); | |
557 | ||
558 | return freed; | |
559 | } | |
560 | ||
561 | /* | |
562 | * journal_clean_checkpoint_list | |
563 | * | |
564 | * Find all the written-back checkpoint buffers in the journal and release them. | |
565 | * | |
566 | * Called with the journal locked. | |
567 | * Called with j_list_lock held. | |
568 | * Returns number of buffers reaped (for debug) | |
569 | */ | |
570 | ||
f7f4bccb | 571 | int __jbd2_journal_clean_checkpoint_list(journal_t *journal) |
470decc6 DK |
572 | { |
573 | transaction_t *transaction, *last_transaction, *next_transaction; | |
574 | int ret = 0; | |
575 | int released; | |
576 | ||
577 | transaction = journal->j_checkpoint_transactions; | |
578 | if (!transaction) | |
579 | goto out; | |
580 | ||
581 | last_transaction = transaction->t_cpprev; | |
582 | next_transaction = transaction; | |
583 | do { | |
584 | transaction = next_transaction; | |
585 | next_transaction = transaction->t_cpnext; | |
586 | ret += journal_clean_one_cp_list(transaction-> | |
587 | t_checkpoint_list, &released); | |
588 | /* | |
589 | * This function only frees up some memory if possible so we | |
590 | * dont have an obligation to finish processing. Bail out if | |
591 | * preemption requested: | |
592 | */ | |
593 | if (need_resched()) | |
594 | goto out; | |
595 | if (released) | |
596 | continue; | |
597 | /* | |
598 | * It is essential that we are as careful as in the case of | |
599 | * t_checkpoint_list with removing the buffer from the list as | |
600 | * we can possibly see not yet submitted buffers on io_list | |
601 | */ | |
602 | ret += journal_clean_one_cp_list(transaction-> | |
603 | t_checkpoint_io_list, &released); | |
604 | if (need_resched()) | |
605 | goto out; | |
606 | } while (transaction != last_transaction); | |
607 | out: | |
608 | return ret; | |
609 | } | |
610 | ||
611 | /* | |
612 | * journal_remove_checkpoint: called after a buffer has been committed | |
613 | * to disk (either by being write-back flushed to disk, or being | |
614 | * committed to the log). | |
615 | * | |
616 | * We cannot safely clean a transaction out of the log until all of the | |
617 | * buffer updates committed in that transaction have safely been stored | |
618 | * elsewhere on disk. To achieve this, all of the buffers in a | |
619 | * transaction need to be maintained on the transaction's checkpoint | |
620 | * lists until they have been rewritten, at which point this function is | |
621 | * called to remove the buffer from the existing transaction's | |
622 | * checkpoint lists. | |
623 | * | |
624 | * The function returns 1 if it frees the transaction, 0 otherwise. | |
625 | * | |
626 | * This function is called with the journal locked. | |
627 | * This function is called with j_list_lock held. | |
628 | * This function is called with jbd_lock_bh_state(jh2bh(jh)) | |
629 | */ | |
630 | ||
f7f4bccb | 631 | int __jbd2_journal_remove_checkpoint(struct journal_head *jh) |
470decc6 DK |
632 | { |
633 | transaction_t *transaction; | |
634 | journal_t *journal; | |
635 | int ret = 0; | |
636 | ||
637 | JBUFFER_TRACE(jh, "entry"); | |
638 | ||
639 | if ((transaction = jh->b_cp_transaction) == NULL) { | |
640 | JBUFFER_TRACE(jh, "not on transaction"); | |
641 | goto out; | |
642 | } | |
643 | journal = transaction->t_journal; | |
644 | ||
645 | __buffer_unlink(jh); | |
646 | jh->b_cp_transaction = NULL; | |
647 | ||
648 | if (transaction->t_checkpoint_list != NULL || | |
649 | transaction->t_checkpoint_io_list != NULL) | |
650 | goto out; | |
651 | JBUFFER_TRACE(jh, "transaction has no more buffers"); | |
652 | ||
653 | /* | |
654 | * There is one special case to worry about: if we have just pulled the | |
f5a7a6b0 JK |
655 | * buffer off a running or committing transaction's checkpoing list, |
656 | * then even if the checkpoint list is empty, the transaction obviously | |
657 | * cannot be dropped! | |
470decc6 | 658 | * |
f5a7a6b0 | 659 | * The locking here around t_state is a bit sleazy. |
f7f4bccb | 660 | * See the comment at the end of jbd2_journal_commit_transaction(). |
470decc6 | 661 | */ |
f5a7a6b0 JK |
662 | if (transaction->t_state != T_FINISHED) { |
663 | JBUFFER_TRACE(jh, "belongs to running/committing transaction"); | |
470decc6 DK |
664 | goto out; |
665 | } | |
666 | ||
667 | /* OK, that was the last buffer for the transaction: we can now | |
668 | safely remove this transaction from the log */ | |
669 | ||
f7f4bccb | 670 | __jbd2_journal_drop_transaction(journal, transaction); |
470decc6 DK |
671 | |
672 | /* Just in case anybody was waiting for more transactions to be | |
673 | checkpointed... */ | |
674 | wake_up(&journal->j_wait_logspace); | |
675 | ret = 1; | |
676 | out: | |
677 | JBUFFER_TRACE(jh, "exit"); | |
678 | return ret; | |
679 | } | |
680 | ||
681 | /* | |
682 | * journal_insert_checkpoint: put a committed buffer onto a checkpoint | |
683 | * list so that we know when it is safe to clean the transaction out of | |
684 | * the log. | |
685 | * | |
686 | * Called with the journal locked. | |
687 | * Called with j_list_lock held. | |
688 | */ | |
f7f4bccb | 689 | void __jbd2_journal_insert_checkpoint(struct journal_head *jh, |
470decc6 DK |
690 | transaction_t *transaction) |
691 | { | |
692 | JBUFFER_TRACE(jh, "entry"); | |
693 | J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh))); | |
694 | J_ASSERT_JH(jh, jh->b_cp_transaction == NULL); | |
695 | ||
696 | jh->b_cp_transaction = transaction; | |
697 | ||
698 | if (!transaction->t_checkpoint_list) { | |
699 | jh->b_cpnext = jh->b_cpprev = jh; | |
700 | } else { | |
701 | jh->b_cpnext = transaction->t_checkpoint_list; | |
702 | jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev; | |
703 | jh->b_cpprev->b_cpnext = jh; | |
704 | jh->b_cpnext->b_cpprev = jh; | |
705 | } | |
706 | transaction->t_checkpoint_list = jh; | |
707 | } | |
708 | ||
709 | /* | |
710 | * We've finished with this transaction structure: adios... | |
711 | * | |
712 | * The transaction must have no links except for the checkpoint by this | |
713 | * point. | |
714 | * | |
715 | * Called with the journal locked. | |
716 | * Called with j_list_lock held. | |
717 | */ | |
718 | ||
f7f4bccb | 719 | void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction) |
470decc6 DK |
720 | { |
721 | assert_spin_locked(&journal->j_list_lock); | |
722 | if (transaction->t_cpnext) { | |
723 | transaction->t_cpnext->t_cpprev = transaction->t_cpprev; | |
724 | transaction->t_cpprev->t_cpnext = transaction->t_cpnext; | |
725 | if (journal->j_checkpoint_transactions == transaction) | |
726 | journal->j_checkpoint_transactions = | |
727 | transaction->t_cpnext; | |
728 | if (journal->j_checkpoint_transactions == transaction) | |
729 | journal->j_checkpoint_transactions = NULL; | |
730 | } | |
731 | ||
732 | J_ASSERT(transaction->t_state == T_FINISHED); | |
733 | J_ASSERT(transaction->t_buffers == NULL); | |
470decc6 DK |
734 | J_ASSERT(transaction->t_forget == NULL); |
735 | J_ASSERT(transaction->t_iobuf_list == NULL); | |
736 | J_ASSERT(transaction->t_shadow_list == NULL); | |
737 | J_ASSERT(transaction->t_log_list == NULL); | |
738 | J_ASSERT(transaction->t_checkpoint_list == NULL); | |
739 | J_ASSERT(transaction->t_checkpoint_io_list == NULL); | |
740 | J_ASSERT(transaction->t_updates == 0); | |
741 | J_ASSERT(journal->j_committing_transaction != transaction); | |
742 | J_ASSERT(journal->j_running_transaction != transaction); | |
743 | ||
744 | jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid); | |
745 | kfree(transaction); | |
746 | } |