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1da177e4 LT |
1 | /* |
2 | * linux/fs/transaction.c | |
3 | * | |
4 | * Written by Stephen C. Tweedie <sct@redhat.com>, 1998 | |
5 | * | |
6 | * Copyright 1998 Red Hat corp --- 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 | * Generic filesystem transaction handling code; part of the ext2fs | |
13 | * journaling system. | |
14 | * | |
15 | * This file manages transactions (compound commits managed by the | |
16 | * journaling code) and handles (individual atomic operations by the | |
17 | * filesystem). | |
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/timer.h> | |
26 | #include <linux/smp_lock.h> | |
27 | #include <linux/mm.h> | |
28 | #include <linux/highmem.h> | |
29 | ||
30 | /* | |
31 | * get_transaction: obtain a new transaction_t object. | |
32 | * | |
33 | * Simply allocate and initialise a new transaction. Create it in | |
34 | * RUNNING state and add it to the current journal (which should not | |
35 | * have an existing running transaction: we only make a new transaction | |
36 | * once we have started to commit the old one). | |
37 | * | |
38 | * Preconditions: | |
39 | * The journal MUST be locked. We don't perform atomic mallocs on the | |
40 | * new transaction and we can't block without protecting against other | |
41 | * processes trying to touch the journal while it is in transition. | |
42 | * | |
43 | * Called under j_state_lock | |
44 | */ | |
45 | ||
46 | static transaction_t * | |
47 | get_transaction(journal_t *journal, transaction_t *transaction) | |
48 | { | |
49 | transaction->t_journal = journal; | |
50 | transaction->t_state = T_RUNNING; | |
51 | transaction->t_tid = journal->j_transaction_sequence++; | |
52 | transaction->t_expires = jiffies + journal->j_commit_interval; | |
53 | spin_lock_init(&transaction->t_handle_lock); | |
54 | ||
55 | /* Set up the commit timer for the new transaction. */ | |
56 | journal->j_commit_timer->expires = transaction->t_expires; | |
57 | add_timer(journal->j_commit_timer); | |
58 | ||
59 | J_ASSERT(journal->j_running_transaction == NULL); | |
60 | journal->j_running_transaction = transaction; | |
61 | ||
62 | return transaction; | |
63 | } | |
64 | ||
65 | /* | |
66 | * Handle management. | |
67 | * | |
68 | * A handle_t is an object which represents a single atomic update to a | |
69 | * filesystem, and which tracks all of the modifications which form part | |
70 | * of that one update. | |
71 | */ | |
72 | ||
73 | /* | |
74 | * start_this_handle: Given a handle, deal with any locking or stalling | |
75 | * needed to make sure that there is enough journal space for the handle | |
76 | * to begin. Attach the handle to a transaction and set up the | |
77 | * transaction's buffer credits. | |
78 | */ | |
79 | ||
80 | static int start_this_handle(journal_t *journal, handle_t *handle) | |
81 | { | |
82 | transaction_t *transaction; | |
83 | int needed; | |
84 | int nblocks = handle->h_buffer_credits; | |
85 | transaction_t *new_transaction = NULL; | |
86 | int ret = 0; | |
87 | ||
88 | if (nblocks > journal->j_max_transaction_buffers) { | |
89 | printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n", | |
90 | current->comm, nblocks, | |
91 | journal->j_max_transaction_buffers); | |
92 | ret = -ENOSPC; | |
93 | goto out; | |
94 | } | |
95 | ||
96 | alloc_transaction: | |
97 | if (!journal->j_running_transaction) { | |
98 | new_transaction = jbd_kmalloc(sizeof(*new_transaction), | |
99 | GFP_NOFS); | |
100 | if (!new_transaction) { | |
101 | ret = -ENOMEM; | |
102 | goto out; | |
103 | } | |
104 | memset(new_transaction, 0, sizeof(*new_transaction)); | |
105 | } | |
106 | ||
107 | jbd_debug(3, "New handle %p going live.\n", handle); | |
108 | ||
109 | repeat: | |
110 | ||
111 | /* | |
112 | * We need to hold j_state_lock until t_updates has been incremented, | |
113 | * for proper journal barrier handling | |
114 | */ | |
115 | spin_lock(&journal->j_state_lock); | |
116 | repeat_locked: | |
117 | if (is_journal_aborted(journal) || | |
118 | (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) { | |
119 | spin_unlock(&journal->j_state_lock); | |
120 | ret = -EROFS; | |
121 | goto out; | |
122 | } | |
123 | ||
124 | /* Wait on the journal's transaction barrier if necessary */ | |
125 | if (journal->j_barrier_count) { | |
126 | spin_unlock(&journal->j_state_lock); | |
127 | wait_event(journal->j_wait_transaction_locked, | |
128 | journal->j_barrier_count == 0); | |
129 | goto repeat; | |
130 | } | |
131 | ||
132 | if (!journal->j_running_transaction) { | |
133 | if (!new_transaction) { | |
134 | spin_unlock(&journal->j_state_lock); | |
135 | goto alloc_transaction; | |
136 | } | |
137 | get_transaction(journal, new_transaction); | |
138 | new_transaction = NULL; | |
139 | } | |
140 | ||
141 | transaction = journal->j_running_transaction; | |
142 | ||
143 | /* | |
144 | * If the current transaction is locked down for commit, wait for the | |
145 | * lock to be released. | |
146 | */ | |
147 | if (transaction->t_state == T_LOCKED) { | |
148 | DEFINE_WAIT(wait); | |
149 | ||
150 | prepare_to_wait(&journal->j_wait_transaction_locked, | |
151 | &wait, TASK_UNINTERRUPTIBLE); | |
152 | spin_unlock(&journal->j_state_lock); | |
153 | schedule(); | |
154 | finish_wait(&journal->j_wait_transaction_locked, &wait); | |
155 | goto repeat; | |
156 | } | |
157 | ||
158 | /* | |
159 | * If there is not enough space left in the log to write all potential | |
160 | * buffers requested by this operation, we need to stall pending a log | |
161 | * checkpoint to free some more log space. | |
162 | */ | |
163 | spin_lock(&transaction->t_handle_lock); | |
164 | needed = transaction->t_outstanding_credits + nblocks; | |
165 | ||
166 | if (needed > journal->j_max_transaction_buffers) { | |
167 | /* | |
168 | * If the current transaction is already too large, then start | |
169 | * to commit it: we can then go back and attach this handle to | |
170 | * a new transaction. | |
171 | */ | |
172 | DEFINE_WAIT(wait); | |
173 | ||
174 | jbd_debug(2, "Handle %p starting new commit...\n", handle); | |
175 | spin_unlock(&transaction->t_handle_lock); | |
176 | prepare_to_wait(&journal->j_wait_transaction_locked, &wait, | |
177 | TASK_UNINTERRUPTIBLE); | |
178 | __log_start_commit(journal, transaction->t_tid); | |
179 | spin_unlock(&journal->j_state_lock); | |
180 | schedule(); | |
181 | finish_wait(&journal->j_wait_transaction_locked, &wait); | |
182 | goto repeat; | |
183 | } | |
184 | ||
185 | /* | |
186 | * The commit code assumes that it can get enough log space | |
187 | * without forcing a checkpoint. This is *critical* for | |
188 | * correctness: a checkpoint of a buffer which is also | |
189 | * associated with a committing transaction creates a deadlock, | |
190 | * so commit simply cannot force through checkpoints. | |
191 | * | |
192 | * We must therefore ensure the necessary space in the journal | |
193 | * *before* starting to dirty potentially checkpointed buffers | |
194 | * in the new transaction. | |
195 | * | |
196 | * The worst part is, any transaction currently committing can | |
197 | * reduce the free space arbitrarily. Be careful to account for | |
198 | * those buffers when checkpointing. | |
199 | */ | |
200 | ||
201 | /* | |
202 | * @@@ AKPM: This seems rather over-defensive. We're giving commit | |
203 | * a _lot_ of headroom: 1/4 of the journal plus the size of | |
204 | * the committing transaction. Really, we only need to give it | |
205 | * committing_transaction->t_outstanding_credits plus "enough" for | |
206 | * the log control blocks. | |
207 | * Also, this test is inconsitent with the matching one in | |
208 | * journal_extend(). | |
209 | */ | |
210 | if (__log_space_left(journal) < jbd_space_needed(journal)) { | |
211 | jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle); | |
212 | spin_unlock(&transaction->t_handle_lock); | |
213 | __log_wait_for_space(journal); | |
214 | goto repeat_locked; | |
215 | } | |
216 | ||
217 | /* OK, account for the buffers that this operation expects to | |
218 | * use and add the handle to the running transaction. */ | |
219 | ||
220 | handle->h_transaction = transaction; | |
221 | transaction->t_outstanding_credits += nblocks; | |
222 | transaction->t_updates++; | |
223 | transaction->t_handle_count++; | |
224 | jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n", | |
225 | handle, nblocks, transaction->t_outstanding_credits, | |
226 | __log_space_left(journal)); | |
227 | spin_unlock(&transaction->t_handle_lock); | |
228 | spin_unlock(&journal->j_state_lock); | |
229 | out: | |
230 | if (new_transaction) | |
231 | kfree(new_transaction); | |
232 | return ret; | |
233 | } | |
234 | ||
235 | /* Allocate a new handle. This should probably be in a slab... */ | |
236 | static handle_t *new_handle(int nblocks) | |
237 | { | |
238 | handle_t *handle = jbd_alloc_handle(GFP_NOFS); | |
239 | if (!handle) | |
240 | return NULL; | |
241 | memset(handle, 0, sizeof(*handle)); | |
242 | handle->h_buffer_credits = nblocks; | |
243 | handle->h_ref = 1; | |
244 | ||
245 | return handle; | |
246 | } | |
247 | ||
248 | /** | |
249 | * handle_t *journal_start() - Obtain a new handle. | |
250 | * @journal: Journal to start transaction on. | |
251 | * @nblocks: number of block buffer we might modify | |
252 | * | |
253 | * We make sure that the transaction can guarantee at least nblocks of | |
254 | * modified buffers in the log. We block until the log can guarantee | |
255 | * that much space. | |
256 | * | |
257 | * This function is visible to journal users (like ext3fs), so is not | |
258 | * called with the journal already locked. | |
259 | * | |
260 | * Return a pointer to a newly allocated handle, or NULL on failure | |
261 | */ | |
262 | handle_t *journal_start(journal_t *journal, int nblocks) | |
263 | { | |
264 | handle_t *handle = journal_current_handle(); | |
265 | int err; | |
266 | ||
267 | if (!journal) | |
268 | return ERR_PTR(-EROFS); | |
269 | ||
270 | if (handle) { | |
271 | J_ASSERT(handle->h_transaction->t_journal == journal); | |
272 | handle->h_ref++; | |
273 | return handle; | |
274 | } | |
275 | ||
276 | handle = new_handle(nblocks); | |
277 | if (!handle) | |
278 | return ERR_PTR(-ENOMEM); | |
279 | ||
280 | current->journal_info = handle; | |
281 | ||
282 | err = start_this_handle(journal, handle); | |
283 | if (err < 0) { | |
284 | jbd_free_handle(handle); | |
285 | current->journal_info = NULL; | |
286 | handle = ERR_PTR(err); | |
287 | } | |
288 | return handle; | |
289 | } | |
290 | ||
291 | /** | |
292 | * int journal_extend() - extend buffer credits. | |
293 | * @handle: handle to 'extend' | |
294 | * @nblocks: nr blocks to try to extend by. | |
295 | * | |
296 | * Some transactions, such as large extends and truncates, can be done | |
297 | * atomically all at once or in several stages. The operation requests | |
298 | * a credit for a number of buffer modications in advance, but can | |
299 | * extend its credit if it needs more. | |
300 | * | |
301 | * journal_extend tries to give the running handle more buffer credits. | |
302 | * It does not guarantee that allocation - this is a best-effort only. | |
303 | * The calling process MUST be able to deal cleanly with a failure to | |
304 | * extend here. | |
305 | * | |
306 | * Return 0 on success, non-zero on failure. | |
307 | * | |
308 | * return code < 0 implies an error | |
309 | * return code > 0 implies normal transaction-full status. | |
310 | */ | |
311 | int journal_extend(handle_t *handle, int nblocks) | |
312 | { | |
313 | transaction_t *transaction = handle->h_transaction; | |
314 | journal_t *journal = transaction->t_journal; | |
315 | int result; | |
316 | int wanted; | |
317 | ||
318 | result = -EIO; | |
319 | if (is_handle_aborted(handle)) | |
320 | goto out; | |
321 | ||
322 | result = 1; | |
323 | ||
324 | spin_lock(&journal->j_state_lock); | |
325 | ||
326 | /* Don't extend a locked-down transaction! */ | |
327 | if (handle->h_transaction->t_state != T_RUNNING) { | |
328 | jbd_debug(3, "denied handle %p %d blocks: " | |
329 | "transaction not running\n", handle, nblocks); | |
330 | goto error_out; | |
331 | } | |
332 | ||
333 | spin_lock(&transaction->t_handle_lock); | |
334 | wanted = transaction->t_outstanding_credits + nblocks; | |
335 | ||
336 | if (wanted > journal->j_max_transaction_buffers) { | |
337 | jbd_debug(3, "denied handle %p %d blocks: " | |
338 | "transaction too large\n", handle, nblocks); | |
339 | goto unlock; | |
340 | } | |
341 | ||
342 | if (wanted > __log_space_left(journal)) { | |
343 | jbd_debug(3, "denied handle %p %d blocks: " | |
344 | "insufficient log space\n", handle, nblocks); | |
345 | goto unlock; | |
346 | } | |
347 | ||
348 | handle->h_buffer_credits += nblocks; | |
349 | transaction->t_outstanding_credits += nblocks; | |
350 | result = 0; | |
351 | ||
352 | jbd_debug(3, "extended handle %p by %d\n", handle, nblocks); | |
353 | unlock: | |
354 | spin_unlock(&transaction->t_handle_lock); | |
355 | error_out: | |
356 | spin_unlock(&journal->j_state_lock); | |
357 | out: | |
358 | return result; | |
359 | } | |
360 | ||
361 | ||
362 | /** | |
363 | * int journal_restart() - restart a handle . | |
364 | * @handle: handle to restart | |
365 | * @nblocks: nr credits requested | |
366 | * | |
367 | * Restart a handle for a multi-transaction filesystem | |
368 | * operation. | |
369 | * | |
370 | * If the journal_extend() call above fails to grant new buffer credits | |
371 | * to a running handle, a call to journal_restart will commit the | |
372 | * handle's transaction so far and reattach the handle to a new | |
373 | * transaction capabable of guaranteeing the requested number of | |
374 | * credits. | |
375 | */ | |
376 | ||
377 | int journal_restart(handle_t *handle, int nblocks) | |
378 | { | |
379 | transaction_t *transaction = handle->h_transaction; | |
380 | journal_t *journal = transaction->t_journal; | |
381 | int ret; | |
382 | ||
383 | /* If we've had an abort of any type, don't even think about | |
384 | * actually doing the restart! */ | |
385 | if (is_handle_aborted(handle)) | |
386 | return 0; | |
387 | ||
388 | /* | |
389 | * First unlink the handle from its current transaction, and start the | |
390 | * commit on that. | |
391 | */ | |
392 | J_ASSERT(transaction->t_updates > 0); | |
393 | J_ASSERT(journal_current_handle() == handle); | |
394 | ||
395 | spin_lock(&journal->j_state_lock); | |
396 | spin_lock(&transaction->t_handle_lock); | |
397 | transaction->t_outstanding_credits -= handle->h_buffer_credits; | |
398 | transaction->t_updates--; | |
399 | ||
400 | if (!transaction->t_updates) | |
401 | wake_up(&journal->j_wait_updates); | |
402 | spin_unlock(&transaction->t_handle_lock); | |
403 | ||
404 | jbd_debug(2, "restarting handle %p\n", handle); | |
405 | __log_start_commit(journal, transaction->t_tid); | |
406 | spin_unlock(&journal->j_state_lock); | |
407 | ||
408 | handle->h_buffer_credits = nblocks; | |
409 | ret = start_this_handle(journal, handle); | |
410 | return ret; | |
411 | } | |
412 | ||
413 | ||
414 | /** | |
415 | * void journal_lock_updates () - establish a transaction barrier. | |
416 | * @journal: Journal to establish a barrier on. | |
417 | * | |
418 | * This locks out any further updates from being started, and blocks | |
419 | * until all existing updates have completed, returning only once the | |
420 | * journal is in a quiescent state with no updates running. | |
421 | * | |
422 | * The journal lock should not be held on entry. | |
423 | */ | |
424 | void journal_lock_updates(journal_t *journal) | |
425 | { | |
426 | DEFINE_WAIT(wait); | |
427 | ||
428 | spin_lock(&journal->j_state_lock); | |
429 | ++journal->j_barrier_count; | |
430 | ||
431 | /* Wait until there are no running updates */ | |
432 | while (1) { | |
433 | transaction_t *transaction = journal->j_running_transaction; | |
434 | ||
435 | if (!transaction) | |
436 | break; | |
437 | ||
438 | spin_lock(&transaction->t_handle_lock); | |
439 | if (!transaction->t_updates) { | |
440 | spin_unlock(&transaction->t_handle_lock); | |
441 | break; | |
442 | } | |
443 | prepare_to_wait(&journal->j_wait_updates, &wait, | |
444 | TASK_UNINTERRUPTIBLE); | |
445 | spin_unlock(&transaction->t_handle_lock); | |
446 | spin_unlock(&journal->j_state_lock); | |
447 | schedule(); | |
448 | finish_wait(&journal->j_wait_updates, &wait); | |
449 | spin_lock(&journal->j_state_lock); | |
450 | } | |
451 | spin_unlock(&journal->j_state_lock); | |
452 | ||
453 | /* | |
454 | * We have now established a barrier against other normal updates, but | |
455 | * we also need to barrier against other journal_lock_updates() calls | |
456 | * to make sure that we serialise special journal-locked operations | |
457 | * too. | |
458 | */ | |
459 | down(&journal->j_barrier); | |
460 | } | |
461 | ||
462 | /** | |
463 | * void journal_unlock_updates (journal_t* journal) - release barrier | |
464 | * @journal: Journal to release the barrier on. | |
465 | * | |
466 | * Release a transaction barrier obtained with journal_lock_updates(). | |
467 | * | |
468 | * Should be called without the journal lock held. | |
469 | */ | |
470 | void journal_unlock_updates (journal_t *journal) | |
471 | { | |
472 | J_ASSERT(journal->j_barrier_count != 0); | |
473 | ||
474 | up(&journal->j_barrier); | |
475 | spin_lock(&journal->j_state_lock); | |
476 | --journal->j_barrier_count; | |
477 | spin_unlock(&journal->j_state_lock); | |
478 | wake_up(&journal->j_wait_transaction_locked); | |
479 | } | |
480 | ||
481 | /* | |
482 | * Report any unexpected dirty buffers which turn up. Normally those | |
483 | * indicate an error, but they can occur if the user is running (say) | |
484 | * tune2fs to modify the live filesystem, so we need the option of | |
485 | * continuing as gracefully as possible. # | |
486 | * | |
487 | * The caller should already hold the journal lock and | |
488 | * j_list_lock spinlock: most callers will need those anyway | |
489 | * in order to probe the buffer's journaling state safely. | |
490 | */ | |
491 | static void jbd_unexpected_dirty_buffer(struct journal_head *jh) | |
492 | { | |
493 | struct buffer_head *bh = jh2bh(jh); | |
494 | int jlist; | |
495 | ||
496 | if (buffer_dirty(bh)) { | |
497 | /* If this buffer is one which might reasonably be dirty | |
498 | * --- ie. data, or not part of this journal --- then | |
499 | * we're OK to leave it alone, but otherwise we need to | |
500 | * move the dirty bit to the journal's own internal | |
501 | * JBDDirty bit. */ | |
502 | jlist = jh->b_jlist; | |
503 | ||
504 | if (jlist == BJ_Metadata || jlist == BJ_Reserved || | |
505 | jlist == BJ_Shadow || jlist == BJ_Forget) { | |
506 | if (test_clear_buffer_dirty(jh2bh(jh))) { | |
507 | set_bit(BH_JBDDirty, &jh2bh(jh)->b_state); | |
508 | } | |
509 | } | |
510 | } | |
511 | } | |
512 | ||
513 | /* | |
514 | * If the buffer is already part of the current transaction, then there | |
515 | * is nothing we need to do. If it is already part of a prior | |
516 | * transaction which we are still committing to disk, then we need to | |
517 | * make sure that we do not overwrite the old copy: we do copy-out to | |
518 | * preserve the copy going to disk. We also account the buffer against | |
519 | * the handle's metadata buffer credits (unless the buffer is already | |
520 | * part of the transaction, that is). | |
521 | * | |
522 | */ | |
523 | static int | |
524 | do_get_write_access(handle_t *handle, struct journal_head *jh, | |
525 | int force_copy) | |
526 | { | |
527 | struct buffer_head *bh; | |
528 | transaction_t *transaction; | |
529 | journal_t *journal; | |
530 | int error; | |
531 | char *frozen_buffer = NULL; | |
532 | int need_copy = 0; | |
533 | ||
534 | if (is_handle_aborted(handle)) | |
535 | return -EROFS; | |
536 | ||
537 | transaction = handle->h_transaction; | |
538 | journal = transaction->t_journal; | |
539 | ||
540 | jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy); | |
541 | ||
542 | JBUFFER_TRACE(jh, "entry"); | |
543 | repeat: | |
544 | bh = jh2bh(jh); | |
545 | ||
546 | /* @@@ Need to check for errors here at some point. */ | |
547 | ||
548 | lock_buffer(bh); | |
549 | jbd_lock_bh_state(bh); | |
550 | ||
551 | /* We now hold the buffer lock so it is safe to query the buffer | |
552 | * state. Is the buffer dirty? | |
553 | * | |
554 | * If so, there are two possibilities. The buffer may be | |
555 | * non-journaled, and undergoing a quite legitimate writeback. | |
556 | * Otherwise, it is journaled, and we don't expect dirty buffers | |
557 | * in that state (the buffers should be marked JBD_Dirty | |
558 | * instead.) So either the IO is being done under our own | |
559 | * control and this is a bug, or it's a third party IO such as | |
560 | * dump(8) (which may leave the buffer scheduled for read --- | |
561 | * ie. locked but not dirty) or tune2fs (which may actually have | |
562 | * the buffer dirtied, ugh.) */ | |
563 | ||
564 | if (buffer_dirty(bh)) { | |
565 | /* | |
566 | * First question: is this buffer already part of the current | |
567 | * transaction or the existing committing transaction? | |
568 | */ | |
569 | if (jh->b_transaction) { | |
570 | J_ASSERT_JH(jh, | |
571 | jh->b_transaction == transaction || | |
572 | jh->b_transaction == | |
573 | journal->j_committing_transaction); | |
574 | if (jh->b_next_transaction) | |
575 | J_ASSERT_JH(jh, jh->b_next_transaction == | |
576 | transaction); | |
577 | JBUFFER_TRACE(jh, "Unexpected dirty buffer"); | |
578 | jbd_unexpected_dirty_buffer(jh); | |
579 | } | |
580 | } | |
581 | ||
582 | unlock_buffer(bh); | |
583 | ||
584 | error = -EROFS; | |
585 | if (is_handle_aborted(handle)) { | |
586 | jbd_unlock_bh_state(bh); | |
587 | goto out; | |
588 | } | |
589 | error = 0; | |
590 | ||
591 | /* | |
592 | * The buffer is already part of this transaction if b_transaction or | |
593 | * b_next_transaction points to it | |
594 | */ | |
595 | if (jh->b_transaction == transaction || | |
596 | jh->b_next_transaction == transaction) | |
597 | goto done; | |
598 | ||
599 | /* | |
600 | * If there is already a copy-out version of this buffer, then we don't | |
601 | * need to make another one | |
602 | */ | |
603 | if (jh->b_frozen_data) { | |
604 | JBUFFER_TRACE(jh, "has frozen data"); | |
605 | J_ASSERT_JH(jh, jh->b_next_transaction == NULL); | |
606 | jh->b_next_transaction = transaction; | |
607 | goto done; | |
608 | } | |
609 | ||
610 | /* Is there data here we need to preserve? */ | |
611 | ||
612 | if (jh->b_transaction && jh->b_transaction != transaction) { | |
613 | JBUFFER_TRACE(jh, "owned by older transaction"); | |
614 | J_ASSERT_JH(jh, jh->b_next_transaction == NULL); | |
615 | J_ASSERT_JH(jh, jh->b_transaction == | |
616 | journal->j_committing_transaction); | |
617 | ||
618 | /* There is one case we have to be very careful about. | |
619 | * If the committing transaction is currently writing | |
620 | * this buffer out to disk and has NOT made a copy-out, | |
621 | * then we cannot modify the buffer contents at all | |
622 | * right now. The essence of copy-out is that it is the | |
623 | * extra copy, not the primary copy, which gets | |
624 | * journaled. If the primary copy is already going to | |
625 | * disk then we cannot do copy-out here. */ | |
626 | ||
627 | if (jh->b_jlist == BJ_Shadow) { | |
628 | DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow); | |
629 | wait_queue_head_t *wqh; | |
630 | ||
631 | wqh = bit_waitqueue(&bh->b_state, BH_Unshadow); | |
632 | ||
633 | JBUFFER_TRACE(jh, "on shadow: sleep"); | |
634 | jbd_unlock_bh_state(bh); | |
635 | /* commit wakes up all shadow buffers after IO */ | |
636 | for ( ; ; ) { | |
637 | prepare_to_wait(wqh, &wait.wait, | |
638 | TASK_UNINTERRUPTIBLE); | |
639 | if (jh->b_jlist != BJ_Shadow) | |
640 | break; | |
641 | schedule(); | |
642 | } | |
643 | finish_wait(wqh, &wait.wait); | |
644 | goto repeat; | |
645 | } | |
646 | ||
647 | /* Only do the copy if the currently-owning transaction | |
648 | * still needs it. If it is on the Forget list, the | |
649 | * committing transaction is past that stage. The | |
650 | * buffer had better remain locked during the kmalloc, | |
651 | * but that should be true --- we hold the journal lock | |
652 | * still and the buffer is already on the BUF_JOURNAL | |
653 | * list so won't be flushed. | |
654 | * | |
655 | * Subtle point, though: if this is a get_undo_access, | |
656 | * then we will be relying on the frozen_data to contain | |
657 | * the new value of the committed_data record after the | |
658 | * transaction, so we HAVE to force the frozen_data copy | |
659 | * in that case. */ | |
660 | ||
661 | if (jh->b_jlist != BJ_Forget || force_copy) { | |
662 | JBUFFER_TRACE(jh, "generate frozen data"); | |
663 | if (!frozen_buffer) { | |
664 | JBUFFER_TRACE(jh, "allocate memory for buffer"); | |
665 | jbd_unlock_bh_state(bh); | |
666 | frozen_buffer = jbd_kmalloc(jh2bh(jh)->b_size, | |
667 | GFP_NOFS); | |
668 | if (!frozen_buffer) { | |
669 | printk(KERN_EMERG | |
670 | "%s: OOM for frozen_buffer\n", | |
671 | __FUNCTION__); | |
672 | JBUFFER_TRACE(jh, "oom!"); | |
673 | error = -ENOMEM; | |
674 | jbd_lock_bh_state(bh); | |
675 | goto done; | |
676 | } | |
677 | goto repeat; | |
678 | } | |
679 | jh->b_frozen_data = frozen_buffer; | |
680 | frozen_buffer = NULL; | |
681 | need_copy = 1; | |
682 | } | |
683 | jh->b_next_transaction = transaction; | |
684 | } | |
685 | ||
686 | ||
687 | /* | |
688 | * Finally, if the buffer is not journaled right now, we need to make | |
689 | * sure it doesn't get written to disk before the caller actually | |
690 | * commits the new data | |
691 | */ | |
692 | if (!jh->b_transaction) { | |
693 | JBUFFER_TRACE(jh, "no transaction"); | |
694 | J_ASSERT_JH(jh, !jh->b_next_transaction); | |
695 | jh->b_transaction = transaction; | |
696 | JBUFFER_TRACE(jh, "file as BJ_Reserved"); | |
697 | spin_lock(&journal->j_list_lock); | |
698 | __journal_file_buffer(jh, transaction, BJ_Reserved); | |
699 | spin_unlock(&journal->j_list_lock); | |
700 | } | |
701 | ||
702 | done: | |
703 | if (need_copy) { | |
704 | struct page *page; | |
705 | int offset; | |
706 | char *source; | |
707 | ||
708 | J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)), | |
709 | "Possible IO failure.\n"); | |
710 | page = jh2bh(jh)->b_page; | |
711 | offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK; | |
712 | source = kmap_atomic(page, KM_USER0); | |
713 | memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size); | |
714 | kunmap_atomic(source, KM_USER0); | |
715 | } | |
716 | jbd_unlock_bh_state(bh); | |
717 | ||
718 | /* | |
719 | * If we are about to journal a buffer, then any revoke pending on it is | |
720 | * no longer valid | |
721 | */ | |
722 | journal_cancel_revoke(handle, jh); | |
723 | ||
724 | out: | |
725 | if (frozen_buffer) | |
726 | kfree(frozen_buffer); | |
727 | ||
728 | JBUFFER_TRACE(jh, "exit"); | |
729 | return error; | |
730 | } | |
731 | ||
732 | /** | |
733 | * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update. | |
734 | * @handle: transaction to add buffer modifications to | |
735 | * @bh: bh to be used for metadata writes | |
736 | * @credits: variable that will receive credits for the buffer | |
737 | * | |
738 | * Returns an error code or 0 on success. | |
739 | * | |
740 | * In full data journalling mode the buffer may be of type BJ_AsyncData, | |
741 | * because we're write()ing a buffer which is also part of a shared mapping. | |
742 | */ | |
743 | ||
744 | int journal_get_write_access(handle_t *handle, struct buffer_head *bh) | |
745 | { | |
746 | struct journal_head *jh = journal_add_journal_head(bh); | |
747 | int rc; | |
748 | ||
749 | /* We do not want to get caught playing with fields which the | |
750 | * log thread also manipulates. Make sure that the buffer | |
751 | * completes any outstanding IO before proceeding. */ | |
752 | rc = do_get_write_access(handle, jh, 0); | |
753 | journal_put_journal_head(jh); | |
754 | return rc; | |
755 | } | |
756 | ||
757 | ||
758 | /* | |
759 | * When the user wants to journal a newly created buffer_head | |
760 | * (ie. getblk() returned a new buffer and we are going to populate it | |
761 | * manually rather than reading off disk), then we need to keep the | |
762 | * buffer_head locked until it has been completely filled with new | |
763 | * data. In this case, we should be able to make the assertion that | |
764 | * the bh is not already part of an existing transaction. | |
765 | * | |
766 | * The buffer should already be locked by the caller by this point. | |
767 | * There is no lock ranking violation: it was a newly created, | |
768 | * unlocked buffer beforehand. */ | |
769 | ||
770 | /** | |
771 | * int journal_get_create_access () - notify intent to use newly created bh | |
772 | * @handle: transaction to new buffer to | |
773 | * @bh: new buffer. | |
774 | * | |
775 | * Call this if you create a new bh. | |
776 | */ | |
777 | int journal_get_create_access(handle_t *handle, struct buffer_head *bh) | |
778 | { | |
779 | transaction_t *transaction = handle->h_transaction; | |
780 | journal_t *journal = transaction->t_journal; | |
781 | struct journal_head *jh = journal_add_journal_head(bh); | |
782 | int err; | |
783 | ||
784 | jbd_debug(5, "journal_head %p\n", jh); | |
785 | err = -EROFS; | |
786 | if (is_handle_aborted(handle)) | |
787 | goto out; | |
788 | err = 0; | |
789 | ||
790 | JBUFFER_TRACE(jh, "entry"); | |
791 | /* | |
792 | * The buffer may already belong to this transaction due to pre-zeroing | |
793 | * in the filesystem's new_block code. It may also be on the previous, | |
794 | * committing transaction's lists, but it HAS to be in Forget state in | |
795 | * that case: the transaction must have deleted the buffer for it to be | |
796 | * reused here. | |
797 | */ | |
798 | jbd_lock_bh_state(bh); | |
799 | spin_lock(&journal->j_list_lock); | |
800 | J_ASSERT_JH(jh, (jh->b_transaction == transaction || | |
801 | jh->b_transaction == NULL || | |
802 | (jh->b_transaction == journal->j_committing_transaction && | |
803 | jh->b_jlist == BJ_Forget))); | |
804 | ||
805 | J_ASSERT_JH(jh, jh->b_next_transaction == NULL); | |
806 | J_ASSERT_JH(jh, buffer_locked(jh2bh(jh))); | |
807 | ||
808 | if (jh->b_transaction == NULL) { | |
809 | jh->b_transaction = transaction; | |
810 | JBUFFER_TRACE(jh, "file as BJ_Reserved"); | |
811 | __journal_file_buffer(jh, transaction, BJ_Reserved); | |
812 | } else if (jh->b_transaction == journal->j_committing_transaction) { | |
813 | JBUFFER_TRACE(jh, "set next transaction"); | |
814 | jh->b_next_transaction = transaction; | |
815 | } | |
816 | spin_unlock(&journal->j_list_lock); | |
817 | jbd_unlock_bh_state(bh); | |
818 | ||
819 | /* | |
820 | * akpm: I added this. ext3_alloc_branch can pick up new indirect | |
821 | * blocks which contain freed but then revoked metadata. We need | |
822 | * to cancel the revoke in case we end up freeing it yet again | |
823 | * and the reallocating as data - this would cause a second revoke, | |
824 | * which hits an assertion error. | |
825 | */ | |
826 | JBUFFER_TRACE(jh, "cancelling revoke"); | |
827 | journal_cancel_revoke(handle, jh); | |
828 | journal_put_journal_head(jh); | |
829 | out: | |
830 | return err; | |
831 | } | |
832 | ||
833 | /** | |
834 | * int journal_get_undo_access() - Notify intent to modify metadata with | |
835 | * non-rewindable consequences | |
836 | * @handle: transaction | |
837 | * @bh: buffer to undo | |
838 | * @credits: store the number of taken credits here (if not NULL) | |
839 | * | |
840 | * Sometimes there is a need to distinguish between metadata which has | |
841 | * been committed to disk and that which has not. The ext3fs code uses | |
842 | * this for freeing and allocating space, we have to make sure that we | |
843 | * do not reuse freed space until the deallocation has been committed, | |
844 | * since if we overwrote that space we would make the delete | |
845 | * un-rewindable in case of a crash. | |
846 | * | |
847 | * To deal with that, journal_get_undo_access requests write access to a | |
848 | * buffer for parts of non-rewindable operations such as delete | |
849 | * operations on the bitmaps. The journaling code must keep a copy of | |
850 | * the buffer's contents prior to the undo_access call until such time | |
851 | * as we know that the buffer has definitely been committed to disk. | |
852 | * | |
853 | * We never need to know which transaction the committed data is part | |
854 | * of, buffers touched here are guaranteed to be dirtied later and so | |
855 | * will be committed to a new transaction in due course, at which point | |
856 | * we can discard the old committed data pointer. | |
857 | * | |
858 | * Returns error number or 0 on success. | |
859 | */ | |
860 | int journal_get_undo_access(handle_t *handle, struct buffer_head *bh) | |
861 | { | |
862 | int err; | |
863 | struct journal_head *jh = journal_add_journal_head(bh); | |
864 | char *committed_data = NULL; | |
865 | ||
866 | JBUFFER_TRACE(jh, "entry"); | |
867 | ||
868 | /* | |
869 | * Do this first --- it can drop the journal lock, so we want to | |
870 | * make sure that obtaining the committed_data is done | |
871 | * atomically wrt. completion of any outstanding commits. | |
872 | */ | |
873 | err = do_get_write_access(handle, jh, 1); | |
874 | if (err) | |
875 | goto out; | |
876 | ||
877 | repeat: | |
878 | if (!jh->b_committed_data) { | |
879 | committed_data = jbd_kmalloc(jh2bh(jh)->b_size, GFP_NOFS); | |
880 | if (!committed_data) { | |
881 | printk(KERN_EMERG "%s: No memory for committed data\n", | |
882 | __FUNCTION__); | |
883 | err = -ENOMEM; | |
884 | goto out; | |
885 | } | |
886 | } | |
887 | ||
888 | jbd_lock_bh_state(bh); | |
889 | if (!jh->b_committed_data) { | |
890 | /* Copy out the current buffer contents into the | |
891 | * preserved, committed copy. */ | |
892 | JBUFFER_TRACE(jh, "generate b_committed data"); | |
893 | if (!committed_data) { | |
894 | jbd_unlock_bh_state(bh); | |
895 | goto repeat; | |
896 | } | |
897 | ||
898 | jh->b_committed_data = committed_data; | |
899 | committed_data = NULL; | |
900 | memcpy(jh->b_committed_data, bh->b_data, bh->b_size); | |
901 | } | |
902 | jbd_unlock_bh_state(bh); | |
903 | out: | |
904 | journal_put_journal_head(jh); | |
905 | if (committed_data) | |
906 | kfree(committed_data); | |
907 | return err; | |
908 | } | |
909 | ||
910 | /** | |
911 | * int journal_dirty_data() - mark a buffer as containing dirty data which | |
912 | * needs to be flushed before we can commit the | |
913 | * current transaction. | |
914 | * @handle: transaction | |
915 | * @bh: bufferhead to mark | |
916 | * | |
917 | * The buffer is placed on the transaction's data list and is marked as | |
918 | * belonging to the transaction. | |
919 | * | |
920 | * Returns error number or 0 on success. | |
921 | * | |
922 | * journal_dirty_data() can be called via page_launder->ext3_writepage | |
923 | * by kswapd. | |
924 | */ | |
925 | int journal_dirty_data(handle_t *handle, struct buffer_head *bh) | |
926 | { | |
927 | journal_t *journal = handle->h_transaction->t_journal; | |
928 | int need_brelse = 0; | |
929 | struct journal_head *jh; | |
930 | ||
931 | if (is_handle_aborted(handle)) | |
932 | return 0; | |
933 | ||
934 | jh = journal_add_journal_head(bh); | |
935 | JBUFFER_TRACE(jh, "entry"); | |
936 | ||
937 | /* | |
938 | * The buffer could *already* be dirty. Writeout can start | |
939 | * at any time. | |
940 | */ | |
941 | jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid); | |
942 | ||
943 | /* | |
944 | * What if the buffer is already part of a running transaction? | |
945 | * | |
946 | * There are two cases: | |
947 | * 1) It is part of the current running transaction. Refile it, | |
948 | * just in case we have allocated it as metadata, deallocated | |
949 | * it, then reallocated it as data. | |
950 | * 2) It is part of the previous, still-committing transaction. | |
951 | * If all we want to do is to guarantee that the buffer will be | |
952 | * written to disk before this new transaction commits, then | |
953 | * being sure that the *previous* transaction has this same | |
954 | * property is sufficient for us! Just leave it on its old | |
955 | * transaction. | |
956 | * | |
957 | * In case (2), the buffer must not already exist as metadata | |
958 | * --- that would violate write ordering (a transaction is free | |
959 | * to write its data at any point, even before the previous | |
960 | * committing transaction has committed). The caller must | |
961 | * never, ever allow this to happen: there's nothing we can do | |
962 | * about it in this layer. | |
963 | */ | |
964 | jbd_lock_bh_state(bh); | |
965 | spin_lock(&journal->j_list_lock); | |
966 | if (jh->b_transaction) { | |
967 | JBUFFER_TRACE(jh, "has transaction"); | |
968 | if (jh->b_transaction != handle->h_transaction) { | |
969 | JBUFFER_TRACE(jh, "belongs to older transaction"); | |
970 | J_ASSERT_JH(jh, jh->b_transaction == | |
971 | journal->j_committing_transaction); | |
972 | ||
973 | /* @@@ IS THIS TRUE ? */ | |
974 | /* | |
975 | * Not any more. Scenario: someone does a write() | |
976 | * in data=journal mode. The buffer's transaction has | |
977 | * moved into commit. Then someone does another | |
978 | * write() to the file. We do the frozen data copyout | |
979 | * and set b_next_transaction to point to j_running_t. | |
980 | * And while we're in that state, someone does a | |
981 | * writepage() in an attempt to pageout the same area | |
982 | * of the file via a shared mapping. At present that | |
983 | * calls journal_dirty_data(), and we get right here. | |
984 | * It may be too late to journal the data. Simply | |
985 | * falling through to the next test will suffice: the | |
986 | * data will be dirty and wil be checkpointed. The | |
987 | * ordering comments in the next comment block still | |
988 | * apply. | |
989 | */ | |
990 | //J_ASSERT_JH(jh, jh->b_next_transaction == NULL); | |
991 | ||
992 | /* | |
993 | * If we're journalling data, and this buffer was | |
994 | * subject to a write(), it could be metadata, forget | |
995 | * or shadow against the committing transaction. Now, | |
996 | * someone has dirtied the same darn page via a mapping | |
997 | * and it is being writepage()'d. | |
998 | * We *could* just steal the page from commit, with some | |
999 | * fancy locking there. Instead, we just skip it - | |
1000 | * don't tie the page's buffers to the new transaction | |
1001 | * at all. | |
1002 | * Implication: if we crash before the writepage() data | |
1003 | * is written into the filesystem, recovery will replay | |
1004 | * the write() data. | |
1005 | */ | |
1006 | if (jh->b_jlist != BJ_None && | |
1007 | jh->b_jlist != BJ_SyncData && | |
1008 | jh->b_jlist != BJ_Locked) { | |
1009 | JBUFFER_TRACE(jh, "Not stealing"); | |
1010 | goto no_journal; | |
1011 | } | |
1012 | ||
1013 | /* | |
1014 | * This buffer may be undergoing writeout in commit. We | |
1015 | * can't return from here and let the caller dirty it | |
1016 | * again because that can cause the write-out loop in | |
1017 | * commit to never terminate. | |
1018 | */ | |
1019 | if (buffer_dirty(bh)) { | |
1020 | get_bh(bh); | |
1021 | spin_unlock(&journal->j_list_lock); | |
1022 | jbd_unlock_bh_state(bh); | |
1023 | need_brelse = 1; | |
1024 | sync_dirty_buffer(bh); | |
1025 | jbd_lock_bh_state(bh); | |
1026 | spin_lock(&journal->j_list_lock); | |
1027 | /* The buffer may become locked again at any | |
1028 | time if it is redirtied */ | |
1029 | } | |
1030 | ||
1031 | /* journal_clean_data_list() may have got there first */ | |
1032 | if (jh->b_transaction != NULL) { | |
1033 | JBUFFER_TRACE(jh, "unfile from commit"); | |
1034 | __journal_temp_unlink_buffer(jh); | |
1035 | /* It still points to the committing | |
1036 | * transaction; move it to this one so | |
1037 | * that the refile assert checks are | |
1038 | * happy. */ | |
1039 | jh->b_transaction = handle->h_transaction; | |
1040 | } | |
1041 | /* The buffer will be refiled below */ | |
1042 | ||
1043 | } | |
1044 | /* | |
1045 | * Special case --- the buffer might actually have been | |
1046 | * allocated and then immediately deallocated in the previous, | |
1047 | * committing transaction, so might still be left on that | |
1048 | * transaction's metadata lists. | |
1049 | */ | |
1050 | if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) { | |
1051 | JBUFFER_TRACE(jh, "not on correct data list: unfile"); | |
1052 | J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow); | |
1053 | __journal_temp_unlink_buffer(jh); | |
1054 | jh->b_transaction = handle->h_transaction; | |
1055 | JBUFFER_TRACE(jh, "file as data"); | |
1056 | __journal_file_buffer(jh, handle->h_transaction, | |
1057 | BJ_SyncData); | |
1058 | } | |
1059 | } else { | |
1060 | JBUFFER_TRACE(jh, "not on a transaction"); | |
1061 | __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData); | |
1062 | } | |
1063 | no_journal: | |
1064 | spin_unlock(&journal->j_list_lock); | |
1065 | jbd_unlock_bh_state(bh); | |
1066 | if (need_brelse) { | |
1067 | BUFFER_TRACE(bh, "brelse"); | |
1068 | __brelse(bh); | |
1069 | } | |
1070 | JBUFFER_TRACE(jh, "exit"); | |
1071 | journal_put_journal_head(jh); | |
1072 | return 0; | |
1073 | } | |
1074 | ||
1075 | /** | |
1076 | * int journal_dirty_metadata() - mark a buffer as containing dirty metadata | |
1077 | * @handle: transaction to add buffer to. | |
1078 | * @bh: buffer to mark | |
1079 | * | |
1080 | * mark dirty metadata which needs to be journaled as part of the current | |
1081 | * transaction. | |
1082 | * | |
1083 | * The buffer is placed on the transaction's metadata list and is marked | |
1084 | * as belonging to the transaction. | |
1085 | * | |
1086 | * Returns error number or 0 on success. | |
1087 | * | |
1088 | * Special care needs to be taken if the buffer already belongs to the | |
1089 | * current committing transaction (in which case we should have frozen | |
1090 | * data present for that commit). In that case, we don't relink the | |
1091 | * buffer: that only gets done when the old transaction finally | |
1092 | * completes its commit. | |
1093 | */ | |
1094 | int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) | |
1095 | { | |
1096 | transaction_t *transaction = handle->h_transaction; | |
1097 | journal_t *journal = transaction->t_journal; | |
1098 | struct journal_head *jh = bh2jh(bh); | |
1099 | ||
1100 | jbd_debug(5, "journal_head %p\n", jh); | |
1101 | JBUFFER_TRACE(jh, "entry"); | |
1102 | if (is_handle_aborted(handle)) | |
1103 | goto out; | |
1104 | ||
1105 | jbd_lock_bh_state(bh); | |
1106 | ||
1107 | if (jh->b_modified == 0) { | |
1108 | /* | |
1109 | * This buffer's got modified and becoming part | |
1110 | * of the transaction. This needs to be done | |
1111 | * once a transaction -bzzz | |
1112 | */ | |
1113 | jh->b_modified = 1; | |
1114 | J_ASSERT_JH(jh, handle->h_buffer_credits > 0); | |
1115 | handle->h_buffer_credits--; | |
1116 | } | |
1117 | ||
1118 | /* | |
1119 | * fastpath, to avoid expensive locking. If this buffer is already | |
1120 | * on the running transaction's metadata list there is nothing to do. | |
1121 | * Nobody can take it off again because there is a handle open. | |
1122 | * I _think_ we're OK here with SMP barriers - a mistaken decision will | |
1123 | * result in this test being false, so we go in and take the locks. | |
1124 | */ | |
1125 | if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) { | |
1126 | JBUFFER_TRACE(jh, "fastpath"); | |
1127 | J_ASSERT_JH(jh, jh->b_transaction == | |
1128 | journal->j_running_transaction); | |
1129 | goto out_unlock_bh; | |
1130 | } | |
1131 | ||
1132 | set_buffer_jbddirty(bh); | |
1133 | ||
1134 | /* | |
1135 | * Metadata already on the current transaction list doesn't | |
1136 | * need to be filed. Metadata on another transaction's list must | |
1137 | * be committing, and will be refiled once the commit completes: | |
1138 | * leave it alone for now. | |
1139 | */ | |
1140 | if (jh->b_transaction != transaction) { | |
1141 | JBUFFER_TRACE(jh, "already on other transaction"); | |
1142 | J_ASSERT_JH(jh, jh->b_transaction == | |
1143 | journal->j_committing_transaction); | |
1144 | J_ASSERT_JH(jh, jh->b_next_transaction == transaction); | |
1145 | /* And this case is illegal: we can't reuse another | |
1146 | * transaction's data buffer, ever. */ | |
1147 | goto out_unlock_bh; | |
1148 | } | |
1149 | ||
1150 | /* That test should have eliminated the following case: */ | |
1151 | J_ASSERT_JH(jh, jh->b_frozen_data == 0); | |
1152 | ||
1153 | JBUFFER_TRACE(jh, "file as BJ_Metadata"); | |
1154 | spin_lock(&journal->j_list_lock); | |
1155 | __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata); | |
1156 | spin_unlock(&journal->j_list_lock); | |
1157 | out_unlock_bh: | |
1158 | jbd_unlock_bh_state(bh); | |
1159 | out: | |
1160 | JBUFFER_TRACE(jh, "exit"); | |
1161 | return 0; | |
1162 | } | |
1163 | ||
1164 | /* | |
1165 | * journal_release_buffer: undo a get_write_access without any buffer | |
1166 | * updates, if the update decided in the end that it didn't need access. | |
1167 | * | |
1168 | */ | |
1169 | void | |
1170 | journal_release_buffer(handle_t *handle, struct buffer_head *bh) | |
1171 | { | |
1172 | BUFFER_TRACE(bh, "entry"); | |
1173 | } | |
1174 | ||
1175 | /** | |
1176 | * void journal_forget() - bforget() for potentially-journaled buffers. | |
1177 | * @handle: transaction handle | |
1178 | * @bh: bh to 'forget' | |
1179 | * | |
1180 | * We can only do the bforget if there are no commits pending against the | |
1181 | * buffer. If the buffer is dirty in the current running transaction we | |
1182 | * can safely unlink it. | |
1183 | * | |
1184 | * bh may not be a journalled buffer at all - it may be a non-JBD | |
1185 | * buffer which came off the hashtable. Check for this. | |
1186 | * | |
1187 | * Decrements bh->b_count by one. | |
1188 | * | |
1189 | * Allow this call even if the handle has aborted --- it may be part of | |
1190 | * the caller's cleanup after an abort. | |
1191 | */ | |
1192 | int journal_forget (handle_t *handle, struct buffer_head *bh) | |
1193 | { | |
1194 | transaction_t *transaction = handle->h_transaction; | |
1195 | journal_t *journal = transaction->t_journal; | |
1196 | struct journal_head *jh; | |
1197 | int drop_reserve = 0; | |
1198 | int err = 0; | |
1199 | ||
1200 | BUFFER_TRACE(bh, "entry"); | |
1201 | ||
1202 | jbd_lock_bh_state(bh); | |
1203 | spin_lock(&journal->j_list_lock); | |
1204 | ||
1205 | if (!buffer_jbd(bh)) | |
1206 | goto not_jbd; | |
1207 | jh = bh2jh(bh); | |
1208 | ||
1209 | /* Critical error: attempting to delete a bitmap buffer, maybe? | |
1210 | * Don't do any jbd operations, and return an error. */ | |
1211 | if (!J_EXPECT_JH(jh, !jh->b_committed_data, | |
1212 | "inconsistent data on disk")) { | |
1213 | err = -EIO; | |
1214 | goto not_jbd; | |
1215 | } | |
1216 | ||
1217 | /* | |
1218 | * The buffer's going from the transaction, we must drop | |
1219 | * all references -bzzz | |
1220 | */ | |
1221 | jh->b_modified = 0; | |
1222 | ||
1223 | if (jh->b_transaction == handle->h_transaction) { | |
1224 | J_ASSERT_JH(jh, !jh->b_frozen_data); | |
1225 | ||
1226 | /* If we are forgetting a buffer which is already part | |
1227 | * of this transaction, then we can just drop it from | |
1228 | * the transaction immediately. */ | |
1229 | clear_buffer_dirty(bh); | |
1230 | clear_buffer_jbddirty(bh); | |
1231 | ||
1232 | JBUFFER_TRACE(jh, "belongs to current transaction: unfile"); | |
1233 | ||
1234 | drop_reserve = 1; | |
1235 | ||
1236 | /* | |
1237 | * We are no longer going to journal this buffer. | |
1238 | * However, the commit of this transaction is still | |
1239 | * important to the buffer: the delete that we are now | |
1240 | * processing might obsolete an old log entry, so by | |
1241 | * committing, we can satisfy the buffer's checkpoint. | |
1242 | * | |
1243 | * So, if we have a checkpoint on the buffer, we should | |
1244 | * now refile the buffer on our BJ_Forget list so that | |
1245 | * we know to remove the checkpoint after we commit. | |
1246 | */ | |
1247 | ||
1248 | if (jh->b_cp_transaction) { | |
1249 | __journal_temp_unlink_buffer(jh); | |
1250 | __journal_file_buffer(jh, transaction, BJ_Forget); | |
1251 | } else { | |
1252 | __journal_unfile_buffer(jh); | |
1253 | journal_remove_journal_head(bh); | |
1254 | __brelse(bh); | |
1255 | if (!buffer_jbd(bh)) { | |
1256 | spin_unlock(&journal->j_list_lock); | |
1257 | jbd_unlock_bh_state(bh); | |
1258 | __bforget(bh); | |
1259 | goto drop; | |
1260 | } | |
1261 | } | |
1262 | } else if (jh->b_transaction) { | |
1263 | J_ASSERT_JH(jh, (jh->b_transaction == | |
1264 | journal->j_committing_transaction)); | |
1265 | /* However, if the buffer is still owned by a prior | |
1266 | * (committing) transaction, we can't drop it yet... */ | |
1267 | JBUFFER_TRACE(jh, "belongs to older transaction"); | |
1268 | /* ... but we CAN drop it from the new transaction if we | |
1269 | * have also modified it since the original commit. */ | |
1270 | ||
1271 | if (jh->b_next_transaction) { | |
1272 | J_ASSERT(jh->b_next_transaction == transaction); | |
1273 | jh->b_next_transaction = NULL; | |
1274 | drop_reserve = 1; | |
1275 | } | |
1276 | } | |
1277 | ||
1278 | not_jbd: | |
1279 | spin_unlock(&journal->j_list_lock); | |
1280 | jbd_unlock_bh_state(bh); | |
1281 | __brelse(bh); | |
1282 | drop: | |
1283 | if (drop_reserve) { | |
1284 | /* no need to reserve log space for this block -bzzz */ | |
1285 | handle->h_buffer_credits++; | |
1286 | } | |
1287 | return err; | |
1288 | } | |
1289 | ||
1290 | /** | |
1291 | * int journal_stop() - complete a transaction | |
1292 | * @handle: tranaction to complete. | |
1293 | * | |
1294 | * All done for a particular handle. | |
1295 | * | |
1296 | * There is not much action needed here. We just return any remaining | |
1297 | * buffer credits to the transaction and remove the handle. The only | |
1298 | * complication is that we need to start a commit operation if the | |
1299 | * filesystem is marked for synchronous update. | |
1300 | * | |
1301 | * journal_stop itself will not usually return an error, but it may | |
1302 | * do so in unusual circumstances. In particular, expect it to | |
1303 | * return -EIO if a journal_abort has been executed since the | |
1304 | * transaction began. | |
1305 | */ | |
1306 | int journal_stop(handle_t *handle) | |
1307 | { | |
1308 | transaction_t *transaction = handle->h_transaction; | |
1309 | journal_t *journal = transaction->t_journal; | |
1310 | int old_handle_count, err; | |
1311 | ||
1312 | J_ASSERT(transaction->t_updates > 0); | |
1313 | J_ASSERT(journal_current_handle() == handle); | |
1314 | ||
1315 | if (is_handle_aborted(handle)) | |
1316 | err = -EIO; | |
1317 | else | |
1318 | err = 0; | |
1319 | ||
1320 | if (--handle->h_ref > 0) { | |
1321 | jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1, | |
1322 | handle->h_ref); | |
1323 | return err; | |
1324 | } | |
1325 | ||
1326 | jbd_debug(4, "Handle %p going down\n", handle); | |
1327 | ||
1328 | /* | |
1329 | * Implement synchronous transaction batching. If the handle | |
1330 | * was synchronous, don't force a commit immediately. Let's | |
1331 | * yield and let another thread piggyback onto this transaction. | |
1332 | * Keep doing that while new threads continue to arrive. | |
1333 | * It doesn't cost much - we're about to run a commit and sleep | |
1334 | * on IO anyway. Speeds up many-threaded, many-dir operations | |
1335 | * by 30x or more... | |
1336 | */ | |
1337 | if (handle->h_sync) { | |
1338 | do { | |
1339 | old_handle_count = transaction->t_handle_count; | |
1340 | set_current_state(TASK_UNINTERRUPTIBLE); | |
1341 | schedule_timeout(1); | |
1342 | } while (old_handle_count != transaction->t_handle_count); | |
1343 | } | |
1344 | ||
1345 | current->journal_info = NULL; | |
1346 | spin_lock(&journal->j_state_lock); | |
1347 | spin_lock(&transaction->t_handle_lock); | |
1348 | transaction->t_outstanding_credits -= handle->h_buffer_credits; | |
1349 | transaction->t_updates--; | |
1350 | if (!transaction->t_updates) { | |
1351 | wake_up(&journal->j_wait_updates); | |
1352 | if (journal->j_barrier_count) | |
1353 | wake_up(&journal->j_wait_transaction_locked); | |
1354 | } | |
1355 | ||
1356 | /* | |
1357 | * If the handle is marked SYNC, we need to set another commit | |
1358 | * going! We also want to force a commit if the current | |
1359 | * transaction is occupying too much of the log, or if the | |
1360 | * transaction is too old now. | |
1361 | */ | |
1362 | if (handle->h_sync || | |
1363 | transaction->t_outstanding_credits > | |
1364 | journal->j_max_transaction_buffers || | |
1365 | time_after_eq(jiffies, transaction->t_expires)) { | |
1366 | /* Do this even for aborted journals: an abort still | |
1367 | * completes the commit thread, it just doesn't write | |
1368 | * anything to disk. */ | |
1369 | tid_t tid = transaction->t_tid; | |
1370 | ||
1371 | spin_unlock(&transaction->t_handle_lock); | |
1372 | jbd_debug(2, "transaction too old, requesting commit for " | |
1373 | "handle %p\n", handle); | |
1374 | /* This is non-blocking */ | |
1375 | __log_start_commit(journal, transaction->t_tid); | |
1376 | spin_unlock(&journal->j_state_lock); | |
1377 | ||
1378 | /* | |
1379 | * Special case: JFS_SYNC synchronous updates require us | |
1380 | * to wait for the commit to complete. | |
1381 | */ | |
1382 | if (handle->h_sync && !(current->flags & PF_MEMALLOC)) | |
1383 | err = log_wait_commit(journal, tid); | |
1384 | } else { | |
1385 | spin_unlock(&transaction->t_handle_lock); | |
1386 | spin_unlock(&journal->j_state_lock); | |
1387 | } | |
1388 | ||
1389 | jbd_free_handle(handle); | |
1390 | return err; | |
1391 | } | |
1392 | ||
1393 | /**int journal_force_commit() - force any uncommitted transactions | |
1394 | * @journal: journal to force | |
1395 | * | |
1396 | * For synchronous operations: force any uncommitted transactions | |
1397 | * to disk. May seem kludgy, but it reuses all the handle batching | |
1398 | * code in a very simple manner. | |
1399 | */ | |
1400 | int journal_force_commit(journal_t *journal) | |
1401 | { | |
1402 | handle_t *handle; | |
1403 | int ret; | |
1404 | ||
1405 | handle = journal_start(journal, 1); | |
1406 | if (IS_ERR(handle)) { | |
1407 | ret = PTR_ERR(handle); | |
1408 | } else { | |
1409 | handle->h_sync = 1; | |
1410 | ret = journal_stop(handle); | |
1411 | } | |
1412 | return ret; | |
1413 | } | |
1414 | ||
1415 | /* | |
1416 | * | |
1417 | * List management code snippets: various functions for manipulating the | |
1418 | * transaction buffer lists. | |
1419 | * | |
1420 | */ | |
1421 | ||
1422 | /* | |
1423 | * Append a buffer to a transaction list, given the transaction's list head | |
1424 | * pointer. | |
1425 | * | |
1426 | * j_list_lock is held. | |
1427 | * | |
1428 | * jbd_lock_bh_state(jh2bh(jh)) is held. | |
1429 | */ | |
1430 | ||
1431 | static inline void | |
1432 | __blist_add_buffer(struct journal_head **list, struct journal_head *jh) | |
1433 | { | |
1434 | if (!*list) { | |
1435 | jh->b_tnext = jh->b_tprev = jh; | |
1436 | *list = jh; | |
1437 | } else { | |
1438 | /* Insert at the tail of the list to preserve order */ | |
1439 | struct journal_head *first = *list, *last = first->b_tprev; | |
1440 | jh->b_tprev = last; | |
1441 | jh->b_tnext = first; | |
1442 | last->b_tnext = first->b_tprev = jh; | |
1443 | } | |
1444 | } | |
1445 | ||
1446 | /* | |
1447 | * Remove a buffer from a transaction list, given the transaction's list | |
1448 | * head pointer. | |
1449 | * | |
1450 | * Called with j_list_lock held, and the journal may not be locked. | |
1451 | * | |
1452 | * jbd_lock_bh_state(jh2bh(jh)) is held. | |
1453 | */ | |
1454 | ||
1455 | static inline void | |
1456 | __blist_del_buffer(struct journal_head **list, struct journal_head *jh) | |
1457 | { | |
1458 | if (*list == jh) { | |
1459 | *list = jh->b_tnext; | |
1460 | if (*list == jh) | |
1461 | *list = NULL; | |
1462 | } | |
1463 | jh->b_tprev->b_tnext = jh->b_tnext; | |
1464 | jh->b_tnext->b_tprev = jh->b_tprev; | |
1465 | } | |
1466 | ||
1467 | /* | |
1468 | * Remove a buffer from the appropriate transaction list. | |
1469 | * | |
1470 | * Note that this function can *change* the value of | |
1471 | * bh->b_transaction->t_sync_datalist, t_buffers, t_forget, | |
1472 | * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller | |
1473 | * is holding onto a copy of one of thee pointers, it could go bad. | |
1474 | * Generally the caller needs to re-read the pointer from the transaction_t. | |
1475 | * | |
1476 | * Called under j_list_lock. The journal may not be locked. | |
1477 | */ | |
1478 | void __journal_temp_unlink_buffer(struct journal_head *jh) | |
1479 | { | |
1480 | struct journal_head **list = NULL; | |
1481 | transaction_t *transaction; | |
1482 | struct buffer_head *bh = jh2bh(jh); | |
1483 | ||
1484 | J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); | |
1485 | transaction = jh->b_transaction; | |
1486 | if (transaction) | |
1487 | assert_spin_locked(&transaction->t_journal->j_list_lock); | |
1488 | ||
1489 | J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); | |
1490 | if (jh->b_jlist != BJ_None) | |
1491 | J_ASSERT_JH(jh, transaction != 0); | |
1492 | ||
1493 | switch (jh->b_jlist) { | |
1494 | case BJ_None: | |
1495 | return; | |
1496 | case BJ_SyncData: | |
1497 | list = &transaction->t_sync_datalist; | |
1498 | break; | |
1499 | case BJ_Metadata: | |
1500 | transaction->t_nr_buffers--; | |
1501 | J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0); | |
1502 | list = &transaction->t_buffers; | |
1503 | break; | |
1504 | case BJ_Forget: | |
1505 | list = &transaction->t_forget; | |
1506 | break; | |
1507 | case BJ_IO: | |
1508 | list = &transaction->t_iobuf_list; | |
1509 | break; | |
1510 | case BJ_Shadow: | |
1511 | list = &transaction->t_shadow_list; | |
1512 | break; | |
1513 | case BJ_LogCtl: | |
1514 | list = &transaction->t_log_list; | |
1515 | break; | |
1516 | case BJ_Reserved: | |
1517 | list = &transaction->t_reserved_list; | |
1518 | break; | |
1519 | case BJ_Locked: | |
1520 | list = &transaction->t_locked_list; | |
1521 | break; | |
1522 | } | |
1523 | ||
1524 | __blist_del_buffer(list, jh); | |
1525 | jh->b_jlist = BJ_None; | |
1526 | if (test_clear_buffer_jbddirty(bh)) | |
1527 | mark_buffer_dirty(bh); /* Expose it to the VM */ | |
1528 | } | |
1529 | ||
1530 | void __journal_unfile_buffer(struct journal_head *jh) | |
1531 | { | |
1532 | __journal_temp_unlink_buffer(jh); | |
1533 | jh->b_transaction = NULL; | |
1534 | } | |
1535 | ||
1536 | void journal_unfile_buffer(journal_t *journal, struct journal_head *jh) | |
1537 | { | |
1538 | jbd_lock_bh_state(jh2bh(jh)); | |
1539 | spin_lock(&journal->j_list_lock); | |
1540 | __journal_unfile_buffer(jh); | |
1541 | spin_unlock(&journal->j_list_lock); | |
1542 | jbd_unlock_bh_state(jh2bh(jh)); | |
1543 | } | |
1544 | ||
1545 | /* | |
1546 | * Called from journal_try_to_free_buffers(). | |
1547 | * | |
1548 | * Called under jbd_lock_bh_state(bh) | |
1549 | */ | |
1550 | static void | |
1551 | __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh) | |
1552 | { | |
1553 | struct journal_head *jh; | |
1554 | ||
1555 | jh = bh2jh(bh); | |
1556 | ||
1557 | if (buffer_locked(bh) || buffer_dirty(bh)) | |
1558 | goto out; | |
1559 | ||
1560 | if (jh->b_next_transaction != 0) | |
1561 | goto out; | |
1562 | ||
1563 | spin_lock(&journal->j_list_lock); | |
1564 | if (jh->b_transaction != 0 && jh->b_cp_transaction == 0) { | |
1565 | if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) { | |
1566 | /* A written-back ordered data buffer */ | |
1567 | JBUFFER_TRACE(jh, "release data"); | |
1568 | __journal_unfile_buffer(jh); | |
1569 | journal_remove_journal_head(bh); | |
1570 | __brelse(bh); | |
1571 | } | |
1572 | } else if (jh->b_cp_transaction != 0 && jh->b_transaction == 0) { | |
1573 | /* written-back checkpointed metadata buffer */ | |
1574 | if (jh->b_jlist == BJ_None) { | |
1575 | JBUFFER_TRACE(jh, "remove from checkpoint list"); | |
1576 | __journal_remove_checkpoint(jh); | |
1577 | journal_remove_journal_head(bh); | |
1578 | __brelse(bh); | |
1579 | } | |
1580 | } | |
1581 | spin_unlock(&journal->j_list_lock); | |
1582 | out: | |
1583 | return; | |
1584 | } | |
1585 | ||
1586 | ||
1587 | /** | |
1588 | * int journal_try_to_free_buffers() - try to free page buffers. | |
1589 | * @journal: journal for operation | |
1590 | * @page: to try and free | |
1591 | * @unused_gfp_mask: unused | |
1592 | * | |
1593 | * | |
1594 | * For all the buffers on this page, | |
1595 | * if they are fully written out ordered data, move them onto BUF_CLEAN | |
1596 | * so try_to_free_buffers() can reap them. | |
1597 | * | |
1598 | * This function returns non-zero if we wish try_to_free_buffers() | |
1599 | * to be called. We do this if the page is releasable by try_to_free_buffers(). | |
1600 | * We also do it if the page has locked or dirty buffers and the caller wants | |
1601 | * us to perform sync or async writeout. | |
1602 | * | |
1603 | * This complicates JBD locking somewhat. We aren't protected by the | |
1604 | * BKL here. We wish to remove the buffer from its committing or | |
1605 | * running transaction's ->t_datalist via __journal_unfile_buffer. | |
1606 | * | |
1607 | * This may *change* the value of transaction_t->t_datalist, so anyone | |
1608 | * who looks at t_datalist needs to lock against this function. | |
1609 | * | |
1610 | * Even worse, someone may be doing a journal_dirty_data on this | |
1611 | * buffer. So we need to lock against that. journal_dirty_data() | |
1612 | * will come out of the lock with the buffer dirty, which makes it | |
1613 | * ineligible for release here. | |
1614 | * | |
1615 | * Who else is affected by this? hmm... Really the only contender | |
1616 | * is do_get_write_access() - it could be looking at the buffer while | |
1617 | * journal_try_to_free_buffer() is changing its state. But that | |
1618 | * cannot happen because we never reallocate freed data as metadata | |
1619 | * while the data is part of a transaction. Yes? | |
1620 | */ | |
1621 | int journal_try_to_free_buffers(journal_t *journal, | |
1622 | struct page *page, int unused_gfp_mask) | |
1623 | { | |
1624 | struct buffer_head *head; | |
1625 | struct buffer_head *bh; | |
1626 | int ret = 0; | |
1627 | ||
1628 | J_ASSERT(PageLocked(page)); | |
1629 | ||
1630 | head = page_buffers(page); | |
1631 | bh = head; | |
1632 | do { | |
1633 | struct journal_head *jh; | |
1634 | ||
1635 | /* | |
1636 | * We take our own ref against the journal_head here to avoid | |
1637 | * having to add tons of locking around each instance of | |
1638 | * journal_remove_journal_head() and journal_put_journal_head(). | |
1639 | */ | |
1640 | jh = journal_grab_journal_head(bh); | |
1641 | if (!jh) | |
1642 | continue; | |
1643 | ||
1644 | jbd_lock_bh_state(bh); | |
1645 | __journal_try_to_free_buffer(journal, bh); | |
1646 | journal_put_journal_head(jh); | |
1647 | jbd_unlock_bh_state(bh); | |
1648 | if (buffer_jbd(bh)) | |
1649 | goto busy; | |
1650 | } while ((bh = bh->b_this_page) != head); | |
1651 | ret = try_to_free_buffers(page); | |
1652 | busy: | |
1653 | return ret; | |
1654 | } | |
1655 | ||
1656 | /* | |
1657 | * This buffer is no longer needed. If it is on an older transaction's | |
1658 | * checkpoint list we need to record it on this transaction's forget list | |
1659 | * to pin this buffer (and hence its checkpointing transaction) down until | |
1660 | * this transaction commits. If the buffer isn't on a checkpoint list, we | |
1661 | * release it. | |
1662 | * Returns non-zero if JBD no longer has an interest in the buffer. | |
1663 | * | |
1664 | * Called under j_list_lock. | |
1665 | * | |
1666 | * Called under jbd_lock_bh_state(bh). | |
1667 | */ | |
1668 | static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction) | |
1669 | { | |
1670 | int may_free = 1; | |
1671 | struct buffer_head *bh = jh2bh(jh); | |
1672 | ||
1673 | __journal_unfile_buffer(jh); | |
1674 | ||
1675 | if (jh->b_cp_transaction) { | |
1676 | JBUFFER_TRACE(jh, "on running+cp transaction"); | |
1677 | __journal_file_buffer(jh, transaction, BJ_Forget); | |
1678 | clear_buffer_jbddirty(bh); | |
1679 | may_free = 0; | |
1680 | } else { | |
1681 | JBUFFER_TRACE(jh, "on running transaction"); | |
1682 | journal_remove_journal_head(bh); | |
1683 | __brelse(bh); | |
1684 | } | |
1685 | return may_free; | |
1686 | } | |
1687 | ||
1688 | /* | |
1689 | * journal_invalidatepage | |
1690 | * | |
1691 | * This code is tricky. It has a number of cases to deal with. | |
1692 | * | |
1693 | * There are two invariants which this code relies on: | |
1694 | * | |
1695 | * i_size must be updated on disk before we start calling invalidatepage on the | |
1696 | * data. | |
1697 | * | |
1698 | * This is done in ext3 by defining an ext3_setattr method which | |
1699 | * updates i_size before truncate gets going. By maintaining this | |
1700 | * invariant, we can be sure that it is safe to throw away any buffers | |
1701 | * attached to the current transaction: once the transaction commits, | |
1702 | * we know that the data will not be needed. | |
1703 | * | |
1704 | * Note however that we can *not* throw away data belonging to the | |
1705 | * previous, committing transaction! | |
1706 | * | |
1707 | * Any disk blocks which *are* part of the previous, committing | |
1708 | * transaction (and which therefore cannot be discarded immediately) are | |
1709 | * not going to be reused in the new running transaction | |
1710 | * | |
1711 | * The bitmap committed_data images guarantee this: any block which is | |
1712 | * allocated in one transaction and removed in the next will be marked | |
1713 | * as in-use in the committed_data bitmap, so cannot be reused until | |
1714 | * the next transaction to delete the block commits. This means that | |
1715 | * leaving committing buffers dirty is quite safe: the disk blocks | |
1716 | * cannot be reallocated to a different file and so buffer aliasing is | |
1717 | * not possible. | |
1718 | * | |
1719 | * | |
1720 | * The above applies mainly to ordered data mode. In writeback mode we | |
1721 | * don't make guarantees about the order in which data hits disk --- in | |
1722 | * particular we don't guarantee that new dirty data is flushed before | |
1723 | * transaction commit --- so it is always safe just to discard data | |
1724 | * immediately in that mode. --sct | |
1725 | */ | |
1726 | ||
1727 | /* | |
1728 | * The journal_unmap_buffer helper function returns zero if the buffer | |
1729 | * concerned remains pinned as an anonymous buffer belonging to an older | |
1730 | * transaction. | |
1731 | * | |
1732 | * We're outside-transaction here. Either or both of j_running_transaction | |
1733 | * and j_committing_transaction may be NULL. | |
1734 | */ | |
1735 | static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh) | |
1736 | { | |
1737 | transaction_t *transaction; | |
1738 | struct journal_head *jh; | |
1739 | int may_free = 1; | |
1740 | int ret; | |
1741 | ||
1742 | BUFFER_TRACE(bh, "entry"); | |
1743 | ||
1744 | /* | |
1745 | * It is safe to proceed here without the j_list_lock because the | |
1746 | * buffers cannot be stolen by try_to_free_buffers as long as we are | |
1747 | * holding the page lock. --sct | |
1748 | */ | |
1749 | ||
1750 | if (!buffer_jbd(bh)) | |
1751 | goto zap_buffer_unlocked; | |
1752 | ||
1753 | spin_lock(&journal->j_state_lock); | |
1754 | jbd_lock_bh_state(bh); | |
1755 | spin_lock(&journal->j_list_lock); | |
1756 | ||
1757 | jh = journal_grab_journal_head(bh); | |
1758 | if (!jh) | |
1759 | goto zap_buffer_no_jh; | |
1760 | ||
1761 | transaction = jh->b_transaction; | |
1762 | if (transaction == NULL) { | |
1763 | /* First case: not on any transaction. If it | |
1764 | * has no checkpoint link, then we can zap it: | |
1765 | * it's a writeback-mode buffer so we don't care | |
1766 | * if it hits disk safely. */ | |
1767 | if (!jh->b_cp_transaction) { | |
1768 | JBUFFER_TRACE(jh, "not on any transaction: zap"); | |
1769 | goto zap_buffer; | |
1770 | } | |
1771 | ||
1772 | if (!buffer_dirty(bh)) { | |
1773 | /* bdflush has written it. We can drop it now */ | |
1774 | goto zap_buffer; | |
1775 | } | |
1776 | ||
1777 | /* OK, it must be in the journal but still not | |
1778 | * written fully to disk: it's metadata or | |
1779 | * journaled data... */ | |
1780 | ||
1781 | if (journal->j_running_transaction) { | |
1782 | /* ... and once the current transaction has | |
1783 | * committed, the buffer won't be needed any | |
1784 | * longer. */ | |
1785 | JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget"); | |
1786 | ret = __dispose_buffer(jh, | |
1787 | journal->j_running_transaction); | |
1788 | journal_put_journal_head(jh); | |
1789 | spin_unlock(&journal->j_list_lock); | |
1790 | jbd_unlock_bh_state(bh); | |
1791 | spin_unlock(&journal->j_state_lock); | |
1792 | return ret; | |
1793 | } else { | |
1794 | /* There is no currently-running transaction. So the | |
1795 | * orphan record which we wrote for this file must have | |
1796 | * passed into commit. We must attach this buffer to | |
1797 | * the committing transaction, if it exists. */ | |
1798 | if (journal->j_committing_transaction) { | |
1799 | JBUFFER_TRACE(jh, "give to committing trans"); | |
1800 | ret = __dispose_buffer(jh, | |
1801 | journal->j_committing_transaction); | |
1802 | journal_put_journal_head(jh); | |
1803 | spin_unlock(&journal->j_list_lock); | |
1804 | jbd_unlock_bh_state(bh); | |
1805 | spin_unlock(&journal->j_state_lock); | |
1806 | return ret; | |
1807 | } else { | |
1808 | /* The orphan record's transaction has | |
1809 | * committed. We can cleanse this buffer */ | |
1810 | clear_buffer_jbddirty(bh); | |
1811 | goto zap_buffer; | |
1812 | } | |
1813 | } | |
1814 | } else if (transaction == journal->j_committing_transaction) { | |
1815 | /* If it is committing, we simply cannot touch it. We | |
1816 | * can remove it's next_transaction pointer from the | |
1817 | * running transaction if that is set, but nothing | |
1818 | * else. */ | |
1819 | JBUFFER_TRACE(jh, "on committing transaction"); | |
1820 | set_buffer_freed(bh); | |
1821 | if (jh->b_next_transaction) { | |
1822 | J_ASSERT(jh->b_next_transaction == | |
1823 | journal->j_running_transaction); | |
1824 | jh->b_next_transaction = NULL; | |
1825 | } | |
1826 | journal_put_journal_head(jh); | |
1827 | spin_unlock(&journal->j_list_lock); | |
1828 | jbd_unlock_bh_state(bh); | |
1829 | spin_unlock(&journal->j_state_lock); | |
1830 | return 0; | |
1831 | } else { | |
1832 | /* Good, the buffer belongs to the running transaction. | |
1833 | * We are writing our own transaction's data, not any | |
1834 | * previous one's, so it is safe to throw it away | |
1835 | * (remember that we expect the filesystem to have set | |
1836 | * i_size already for this truncate so recovery will not | |
1837 | * expose the disk blocks we are discarding here.) */ | |
1838 | J_ASSERT_JH(jh, transaction == journal->j_running_transaction); | |
1839 | may_free = __dispose_buffer(jh, transaction); | |
1840 | } | |
1841 | ||
1842 | zap_buffer: | |
1843 | journal_put_journal_head(jh); | |
1844 | zap_buffer_no_jh: | |
1845 | spin_unlock(&journal->j_list_lock); | |
1846 | jbd_unlock_bh_state(bh); | |
1847 | spin_unlock(&journal->j_state_lock); | |
1848 | zap_buffer_unlocked: | |
1849 | clear_buffer_dirty(bh); | |
1850 | J_ASSERT_BH(bh, !buffer_jbddirty(bh)); | |
1851 | clear_buffer_mapped(bh); | |
1852 | clear_buffer_req(bh); | |
1853 | clear_buffer_new(bh); | |
1854 | bh->b_bdev = NULL; | |
1855 | return may_free; | |
1856 | } | |
1857 | ||
1858 | /** | |
1859 | * int journal_invalidatepage() | |
1860 | * @journal: journal to use for flush... | |
1861 | * @page: page to flush | |
1862 | * @offset: length of page to invalidate. | |
1863 | * | |
1864 | * Reap page buffers containing data after offset in page. | |
1865 | * | |
1866 | * Return non-zero if the page's buffers were successfully reaped. | |
1867 | */ | |
1868 | int journal_invalidatepage(journal_t *journal, | |
1869 | struct page *page, | |
1870 | unsigned long offset) | |
1871 | { | |
1872 | struct buffer_head *head, *bh, *next; | |
1873 | unsigned int curr_off = 0; | |
1874 | int may_free = 1; | |
1875 | ||
1876 | if (!PageLocked(page)) | |
1877 | BUG(); | |
1878 | if (!page_has_buffers(page)) | |
1879 | return 1; | |
1880 | ||
1881 | /* We will potentially be playing with lists other than just the | |
1882 | * data lists (especially for journaled data mode), so be | |
1883 | * cautious in our locking. */ | |
1884 | ||
1885 | head = bh = page_buffers(page); | |
1886 | do { | |
1887 | unsigned int next_off = curr_off + bh->b_size; | |
1888 | next = bh->b_this_page; | |
1889 | ||
1890 | /* AKPM: doing lock_buffer here may be overly paranoid */ | |
1891 | if (offset <= curr_off) { | |
1892 | /* This block is wholly outside the truncation point */ | |
1893 | lock_buffer(bh); | |
1894 | may_free &= journal_unmap_buffer(journal, bh); | |
1895 | unlock_buffer(bh); | |
1896 | } | |
1897 | curr_off = next_off; | |
1898 | bh = next; | |
1899 | ||
1900 | } while (bh != head); | |
1901 | ||
1902 | if (!offset) { | |
1903 | if (!may_free || !try_to_free_buffers(page)) | |
1904 | return 0; | |
1905 | J_ASSERT(!page_has_buffers(page)); | |
1906 | } | |
1907 | return 1; | |
1908 | } | |
1909 | ||
1910 | /* | |
1911 | * File a buffer on the given transaction list. | |
1912 | */ | |
1913 | void __journal_file_buffer(struct journal_head *jh, | |
1914 | transaction_t *transaction, int jlist) | |
1915 | { | |
1916 | struct journal_head **list = NULL; | |
1917 | int was_dirty = 0; | |
1918 | struct buffer_head *bh = jh2bh(jh); | |
1919 | ||
1920 | J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); | |
1921 | assert_spin_locked(&transaction->t_journal->j_list_lock); | |
1922 | ||
1923 | J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); | |
1924 | J_ASSERT_JH(jh, jh->b_transaction == transaction || | |
1925 | jh->b_transaction == 0); | |
1926 | ||
1927 | if (jh->b_transaction && jh->b_jlist == jlist) | |
1928 | return; | |
1929 | ||
1930 | /* The following list of buffer states needs to be consistent | |
1931 | * with __jbd_unexpected_dirty_buffer()'s handling of dirty | |
1932 | * state. */ | |
1933 | ||
1934 | if (jlist == BJ_Metadata || jlist == BJ_Reserved || | |
1935 | jlist == BJ_Shadow || jlist == BJ_Forget) { | |
1936 | if (test_clear_buffer_dirty(bh) || | |
1937 | test_clear_buffer_jbddirty(bh)) | |
1938 | was_dirty = 1; | |
1939 | } | |
1940 | ||
1941 | if (jh->b_transaction) | |
1942 | __journal_temp_unlink_buffer(jh); | |
1943 | jh->b_transaction = transaction; | |
1944 | ||
1945 | switch (jlist) { | |
1946 | case BJ_None: | |
1947 | J_ASSERT_JH(jh, !jh->b_committed_data); | |
1948 | J_ASSERT_JH(jh, !jh->b_frozen_data); | |
1949 | return; | |
1950 | case BJ_SyncData: | |
1951 | list = &transaction->t_sync_datalist; | |
1952 | break; | |
1953 | case BJ_Metadata: | |
1954 | transaction->t_nr_buffers++; | |
1955 | list = &transaction->t_buffers; | |
1956 | break; | |
1957 | case BJ_Forget: | |
1958 | list = &transaction->t_forget; | |
1959 | break; | |
1960 | case BJ_IO: | |
1961 | list = &transaction->t_iobuf_list; | |
1962 | break; | |
1963 | case BJ_Shadow: | |
1964 | list = &transaction->t_shadow_list; | |
1965 | break; | |
1966 | case BJ_LogCtl: | |
1967 | list = &transaction->t_log_list; | |
1968 | break; | |
1969 | case BJ_Reserved: | |
1970 | list = &transaction->t_reserved_list; | |
1971 | break; | |
1972 | case BJ_Locked: | |
1973 | list = &transaction->t_locked_list; | |
1974 | break; | |
1975 | } | |
1976 | ||
1977 | __blist_add_buffer(list, jh); | |
1978 | jh->b_jlist = jlist; | |
1979 | ||
1980 | if (was_dirty) | |
1981 | set_buffer_jbddirty(bh); | |
1982 | } | |
1983 | ||
1984 | void journal_file_buffer(struct journal_head *jh, | |
1985 | transaction_t *transaction, int jlist) | |
1986 | { | |
1987 | jbd_lock_bh_state(jh2bh(jh)); | |
1988 | spin_lock(&transaction->t_journal->j_list_lock); | |
1989 | __journal_file_buffer(jh, transaction, jlist); | |
1990 | spin_unlock(&transaction->t_journal->j_list_lock); | |
1991 | jbd_unlock_bh_state(jh2bh(jh)); | |
1992 | } | |
1993 | ||
1994 | /* | |
1995 | * Remove a buffer from its current buffer list in preparation for | |
1996 | * dropping it from its current transaction entirely. If the buffer has | |
1997 | * already started to be used by a subsequent transaction, refile the | |
1998 | * buffer on that transaction's metadata list. | |
1999 | * | |
2000 | * Called under journal->j_list_lock | |
2001 | * | |
2002 | * Called under jbd_lock_bh_state(jh2bh(jh)) | |
2003 | */ | |
2004 | void __journal_refile_buffer(struct journal_head *jh) | |
2005 | { | |
2006 | int was_dirty; | |
2007 | struct buffer_head *bh = jh2bh(jh); | |
2008 | ||
2009 | J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); | |
2010 | if (jh->b_transaction) | |
2011 | assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock); | |
2012 | ||
2013 | /* If the buffer is now unused, just drop it. */ | |
2014 | if (jh->b_next_transaction == NULL) { | |
2015 | __journal_unfile_buffer(jh); | |
2016 | return; | |
2017 | } | |
2018 | ||
2019 | /* | |
2020 | * It has been modified by a later transaction: add it to the new | |
2021 | * transaction's metadata list. | |
2022 | */ | |
2023 | ||
2024 | was_dirty = test_clear_buffer_jbddirty(bh); | |
2025 | __journal_temp_unlink_buffer(jh); | |
2026 | jh->b_transaction = jh->b_next_transaction; | |
2027 | jh->b_next_transaction = NULL; | |
2028 | __journal_file_buffer(jh, jh->b_transaction, BJ_Metadata); | |
2029 | J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING); | |
2030 | ||
2031 | if (was_dirty) | |
2032 | set_buffer_jbddirty(bh); | |
2033 | } | |
2034 | ||
2035 | /* | |
2036 | * For the unlocked version of this call, also make sure that any | |
2037 | * hanging journal_head is cleaned up if necessary. | |
2038 | * | |
2039 | * __journal_refile_buffer is usually called as part of a single locked | |
2040 | * operation on a buffer_head, in which the caller is probably going to | |
2041 | * be hooking the journal_head onto other lists. In that case it is up | |
2042 | * to the caller to remove the journal_head if necessary. For the | |
2043 | * unlocked journal_refile_buffer call, the caller isn't going to be | |
2044 | * doing anything else to the buffer so we need to do the cleanup | |
2045 | * ourselves to avoid a jh leak. | |
2046 | * | |
2047 | * *** The journal_head may be freed by this call! *** | |
2048 | */ | |
2049 | void journal_refile_buffer(journal_t *journal, struct journal_head *jh) | |
2050 | { | |
2051 | struct buffer_head *bh = jh2bh(jh); | |
2052 | ||
2053 | jbd_lock_bh_state(bh); | |
2054 | spin_lock(&journal->j_list_lock); | |
2055 | ||
2056 | __journal_refile_buffer(jh); | |
2057 | jbd_unlock_bh_state(bh); | |
2058 | journal_remove_journal_head(bh); | |
2059 | ||
2060 | spin_unlock(&journal->j_list_lock); | |
2061 | __brelse(bh); | |
2062 | } |