Line data Source code
1 : /*
2 : * linux/fs/jbd/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/mm.h>
27 : #include <linux/highmem.h>
28 : #include <linux/hrtimer.h>
29 :
30 : static void __journal_temp_unlink_buffer(struct journal_head *jh);
31 :
32 : /*
33 : * get_transaction: obtain a new transaction_t object.
34 : *
35 : * Simply allocate and initialise a new transaction. Create it in
36 : * RUNNING state and add it to the current journal (which should not
37 : * have an existing running transaction: we only make a new transaction
38 : * once we have started to commit the old one).
39 : *
40 : * Preconditions:
41 : * The journal MUST be locked. We don't perform atomic mallocs on the
42 : * new transaction and we can't block without protecting against other
43 : * processes trying to touch the journal while it is in transition.
44 : *
45 : * Called under j_state_lock
46 : */
47 :
48 : static transaction_t *
49 : get_transaction(journal_t *journal, transaction_t *transaction)
50 : {
51 0 : transaction->t_journal = journal;
52 0 : transaction->t_state = T_RUNNING;
53 0 : transaction->t_start_time = ktime_get();
54 0 : transaction->t_tid = journal->j_transaction_sequence++;
55 0 : transaction->t_expires = jiffies + journal->j_commit_interval;
56 0 : spin_lock_init(&transaction->t_handle_lock);
57 :
58 : /* Set up the commit timer for the new transaction. */
59 0 : journal->j_commit_timer.expires =
60 : round_jiffies_up(transaction->t_expires);
61 0 : add_timer(&journal->j_commit_timer);
62 :
63 0 : J_ASSERT(journal->j_running_transaction == NULL);
64 0 : journal->j_running_transaction = transaction;
65 :
66 0 : return transaction;
67 : }
68 :
69 : /*
70 : * Handle management.
71 : *
72 : * A handle_t is an object which represents a single atomic update to a
73 : * filesystem, and which tracks all of the modifications which form part
74 : * of that one update.
75 : */
76 :
77 : /*
78 : * start_this_handle: Given a handle, deal with any locking or stalling
79 : * needed to make sure that there is enough journal space for the handle
80 : * to begin. Attach the handle to a transaction and set up the
81 : * transaction's buffer credits.
82 : */
83 :
84 : static int start_this_handle(journal_t *journal, handle_t *handle)
85 : {
86 0 : transaction_t *transaction;
87 0 : int needed;
88 0 : int nblocks = handle->h_buffer_credits;
89 0 : transaction_t *new_transaction = NULL;
90 0 : int ret = 0;
91 0 :
92 0 : if (nblocks > journal->j_max_transaction_buffers) {
93 0 : printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
94 0 : current->comm, nblocks,
95 0 : journal->j_max_transaction_buffers);
96 0 : ret = -ENOSPC;
97 0 : goto out;
98 0 : }
99 0 :
100 0 : alloc_transaction:
101 0 : if (!journal->j_running_transaction) {
102 0 : new_transaction = kzalloc(sizeof(*new_transaction),
103 : GFP_NOFS|__GFP_NOFAIL);
104 0 : if (!new_transaction) {
105 0 : ret = -ENOMEM;
106 0 : goto out;
107 : }
108 : }
109 :
110 : jbd_debug(3, "New handle %p going live.\n", handle);
111 :
112 : repeat:
113 0 :
114 : /*
115 : * We need to hold j_state_lock until t_updates has been incremented,
116 : * for proper journal barrier handling
117 : */
118 0 : spin_lock(&journal->j_state_lock);
119 : repeat_locked:
120 0 : if (is_journal_aborted(journal) ||
121 : (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) {
122 0 : spin_unlock(&journal->j_state_lock);
123 0 : ret = -EROFS;
124 0 : goto out;
125 : }
126 :
127 : /* Wait on the journal's transaction barrier if necessary */
128 0 : if (journal->j_barrier_count) {
129 0 : spin_unlock(&journal->j_state_lock);
130 0 : wait_event(journal->j_wait_transaction_locked,
131 0 : journal->j_barrier_count == 0);
132 0 : goto repeat;
133 : }
134 :
135 0 : if (!journal->j_running_transaction) {
136 0 : if (!new_transaction) {
137 0 : spin_unlock(&journal->j_state_lock);
138 0 : goto alloc_transaction;
139 : }
140 0 : get_transaction(journal, new_transaction);
141 0 : new_transaction = NULL;
142 : }
143 :
144 0 : transaction = journal->j_running_transaction;
145 :
146 : /*
147 : * If the current transaction is locked down for commit, wait for the
148 : * lock to be released.
149 : */
150 0 : if (transaction->t_state == T_LOCKED) {
151 0 : DEFINE_WAIT(wait);
152 :
153 0 : prepare_to_wait(&journal->j_wait_transaction_locked,
154 : &wait, TASK_UNINTERRUPTIBLE);
155 0 : spin_unlock(&journal->j_state_lock);
156 0 : schedule();
157 0 : finish_wait(&journal->j_wait_transaction_locked, &wait);
158 0 : goto repeat;
159 : }
160 :
161 : /*
162 : * If there is not enough space left in the log to write all potential
163 : * buffers requested by this operation, we need to stall pending a log
164 : * checkpoint to free some more log space.
165 : */
166 0 : spin_lock(&transaction->t_handle_lock);
167 0 : needed = transaction->t_outstanding_credits + nblocks;
168 :
169 0 : if (needed > journal->j_max_transaction_buffers) {
170 : /*
171 : * If the current transaction is already too large, then start
172 : * to commit it: we can then go back and attach this handle to
173 : * a new transaction.
174 : */
175 0 : DEFINE_WAIT(wait);
176 :
177 : jbd_debug(2, "Handle %p starting new commit...\n", handle);
178 0 : spin_unlock(&transaction->t_handle_lock);
179 0 : prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
180 : TASK_UNINTERRUPTIBLE);
181 0 : __log_start_commit(journal, transaction->t_tid);
182 0 : spin_unlock(&journal->j_state_lock);
183 0 : schedule();
184 0 : finish_wait(&journal->j_wait_transaction_locked, &wait);
185 0 : goto repeat;
186 : }
187 :
188 : /*
189 : * The commit code assumes that it can get enough log space
190 : * without forcing a checkpoint. This is *critical* for
191 : * correctness: a checkpoint of a buffer which is also
192 : * associated with a committing transaction creates a deadlock,
193 : * so commit simply cannot force through checkpoints.
194 : *
195 : * We must therefore ensure the necessary space in the journal
196 : * *before* starting to dirty potentially checkpointed buffers
197 : * in the new transaction.
198 : *
199 : * The worst part is, any transaction currently committing can
200 : * reduce the free space arbitrarily. Be careful to account for
201 : * those buffers when checkpointing.
202 : */
203 :
204 : /*
205 : * @@@ AKPM: This seems rather over-defensive. We're giving commit
206 : * a _lot_ of headroom: 1/4 of the journal plus the size of
207 : * the committing transaction. Really, we only need to give it
208 : * committing_transaction->t_outstanding_credits plus "enough" for
209 : * the log control blocks.
210 : * Also, this test is inconsitent with the matching one in
211 : * journal_extend().
212 : */
213 0 : if (__log_space_left(journal) < jbd_space_needed(journal)) {
214 : jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
215 0 : spin_unlock(&transaction->t_handle_lock);
216 0 : __log_wait_for_space(journal);
217 0 : goto repeat_locked;
218 : }
219 :
220 : /* OK, account for the buffers that this operation expects to
221 : * use and add the handle to the running transaction. */
222 :
223 0 : handle->h_transaction = transaction;
224 0 : transaction->t_outstanding_credits += nblocks;
225 0 : transaction->t_updates++;
226 0 : transaction->t_handle_count++;
227 : jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
228 : handle, nblocks, transaction->t_outstanding_credits,
229 : __log_space_left(journal));
230 0 : spin_unlock(&transaction->t_handle_lock);
231 0 : spin_unlock(&journal->j_state_lock);
232 :
233 0 : lock_map_acquire(&handle->h_lockdep_map);
234 : out:
235 0 : if (unlikely(new_transaction)) /* It's usually NULL */
236 0 : kfree(new_transaction);
237 0 : return ret;
238 : }
239 :
240 : static struct lock_class_key jbd_handle_key;
241 :
242 : /* Allocate a new handle. This should probably be in a slab... */
243 : static handle_t *new_handle(int nblocks)
244 : {
245 0 : handle_t *handle = jbd_alloc_handle(GFP_NOFS);
246 0 : if (!handle)
247 0 : return NULL;
248 0 : memset(handle, 0, sizeof(*handle));
249 0 : handle->h_buffer_credits = nblocks;
250 0 : handle->h_ref = 1;
251 :
252 : lockdep_init_map(&handle->h_lockdep_map, "jbd_handle", &jbd_handle_key, 0);
253 :
254 0 : return handle;
255 : }
256 :
257 : /**
258 : * handle_t *journal_start() - Obtain a new handle.
259 : * @journal: Journal to start transaction on.
260 : * @nblocks: number of block buffer we might modify
261 : *
262 : * We make sure that the transaction can guarantee at least nblocks of
263 : * modified buffers in the log. We block until the log can guarantee
264 : * that much space.
265 : *
266 : * This function is visible to journal users (like ext3fs), so is not
267 : * called with the journal already locked.
268 : *
269 : * Return a pointer to a newly allocated handle, or NULL on failure
270 : */
271 : handle_t *journal_start(journal_t *journal, int nblocks)
272 : {
273 0 : handle_t *handle = journal_current_handle();
274 0 : int err;
275 0 :
276 0 : if (!journal)
277 0 : return ERR_PTR(-EROFS);
278 0 :
279 0 : if (handle) {
280 0 : J_ASSERT(handle->h_transaction->t_journal == journal);
281 0 : handle->h_ref++;
282 0 : return handle;
283 : }
284 :
285 0 : handle = new_handle(nblocks);
286 0 : if (!handle)
287 0 : return ERR_PTR(-ENOMEM);
288 :
289 0 : current->journal_info = handle;
290 :
291 0 : err = start_this_handle(journal, handle);
292 0 : if (err < 0) {
293 0 : jbd_free_handle(handle);
294 0 : current->journal_info = NULL;
295 0 : handle = ERR_PTR(err);
296 0 : goto out;
297 : }
298 : out:
299 0 : return handle;
300 0 : }
301 :
302 : /**
303 : * int journal_extend() - extend buffer credits.
304 : * @handle: handle to 'extend'
305 : * @nblocks: nr blocks to try to extend by.
306 : *
307 : * Some transactions, such as large extends and truncates, can be done
308 : * atomically all at once or in several stages. The operation requests
309 : * a credit for a number of buffer modications in advance, but can
310 : * extend its credit if it needs more.
311 : *
312 : * journal_extend tries to give the running handle more buffer credits.
313 : * It does not guarantee that allocation - this is a best-effort only.
314 : * The calling process MUST be able to deal cleanly with a failure to
315 : * extend here.
316 : *
317 : * Return 0 on success, non-zero on failure.
318 : *
319 : * return code < 0 implies an error
320 : * return code > 0 implies normal transaction-full status.
321 : */
322 : int journal_extend(handle_t *handle, int nblocks)
323 : {
324 0 : transaction_t *transaction = handle->h_transaction;
325 0 : journal_t *journal = transaction->t_journal;
326 0 : int result;
327 0 : int wanted;
328 0 :
329 0 : result = -EIO;
330 0 : if (is_handle_aborted(handle))
331 0 : goto out;
332 :
333 0 : result = 1;
334 :
335 0 : spin_lock(&journal->j_state_lock);
336 :
337 : /* Don't extend a locked-down transaction! */
338 0 : if (handle->h_transaction->t_state != T_RUNNING) {
339 : jbd_debug(3, "denied handle %p %d blocks: "
340 : "transaction not running\n", handle, nblocks);
341 0 : goto error_out;
342 : }
343 :
344 0 : spin_lock(&transaction->t_handle_lock);
345 0 : wanted = transaction->t_outstanding_credits + nblocks;
346 :
347 0 : if (wanted > journal->j_max_transaction_buffers) {
348 : jbd_debug(3, "denied handle %p %d blocks: "
349 : "transaction too large\n", handle, nblocks);
350 0 : goto unlock;
351 : }
352 :
353 0 : if (wanted > __log_space_left(journal)) {
354 : jbd_debug(3, "denied handle %p %d blocks: "
355 : "insufficient log space\n", handle, nblocks);
356 0 : goto unlock;
357 : }
358 :
359 0 : handle->h_buffer_credits += nblocks;
360 0 : transaction->t_outstanding_credits += nblocks;
361 0 : result = 0;
362 0 :
363 : jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
364 : unlock:
365 0 : spin_unlock(&transaction->t_handle_lock);
366 : error_out:
367 0 : spin_unlock(&journal->j_state_lock);
368 : out:
369 0 : return result;
370 : }
371 :
372 :
373 : /**
374 : * int journal_restart() - restart a handle.
375 : * @handle: handle to restart
376 : * @nblocks: nr credits requested
377 : *
378 : * Restart a handle for a multi-transaction filesystem
379 : * operation.
380 : *
381 : * If the journal_extend() call above fails to grant new buffer credits
382 : * to a running handle, a call to journal_restart will commit the
383 : * handle's transaction so far and reattach the handle to a new
384 : * transaction capabable of guaranteeing the requested number of
385 : * credits.
386 : */
387 :
388 : int journal_restart(handle_t *handle, int nblocks)
389 : {
390 0 : transaction_t *transaction = handle->h_transaction;
391 0 : journal_t *journal = transaction->t_journal;
392 0 : int ret;
393 0 :
394 0 : /* If we've had an abort of any type, don't even think about
395 0 : * actually doing the restart! */
396 0 : if (is_handle_aborted(handle))
397 0 : return 0;
398 :
399 : /*
400 : * First unlink the handle from its current transaction, and start the
401 : * commit on that.
402 : */
403 0 : J_ASSERT(transaction->t_updates > 0);
404 0 : J_ASSERT(journal_current_handle() == handle);
405 :
406 0 : spin_lock(&journal->j_state_lock);
407 0 : spin_lock(&transaction->t_handle_lock);
408 0 : transaction->t_outstanding_credits -= handle->h_buffer_credits;
409 0 : transaction->t_updates--;
410 :
411 0 : if (!transaction->t_updates)
412 0 : wake_up(&journal->j_wait_updates);
413 0 : spin_unlock(&transaction->t_handle_lock);
414 :
415 : jbd_debug(2, "restarting handle %p\n", handle);
416 0 : __log_start_commit(journal, transaction->t_tid);
417 0 : spin_unlock(&journal->j_state_lock);
418 :
419 : lock_map_release(&handle->h_lockdep_map);
420 0 : handle->h_buffer_credits = nblocks;
421 0 : ret = start_this_handle(journal, handle);
422 0 : return ret;
423 : }
424 :
425 :
426 : /**
427 : * void journal_lock_updates () - establish a transaction barrier.
428 : * @journal: Journal to establish a barrier on.
429 : *
430 : * This locks out any further updates from being started, and blocks
431 : * until all existing updates have completed, returning only once the
432 : * journal is in a quiescent state with no updates running.
433 : *
434 : * The journal lock should not be held on entry.
435 : */
436 : void journal_lock_updates(journal_t *journal)
437 : {
438 0 : DEFINE_WAIT(wait);
439 0 :
440 0 : spin_lock(&journal->j_state_lock);
441 0 : ++journal->j_barrier_count;
442 :
443 0 : /* Wait until there are no running updates */
444 : while (1) {
445 0 : transaction_t *transaction = journal->j_running_transaction;
446 :
447 0 : if (!transaction)
448 0 : break;
449 :
450 0 : spin_lock(&transaction->t_handle_lock);
451 0 : if (!transaction->t_updates) {
452 0 : spin_unlock(&transaction->t_handle_lock);
453 0 : break;
454 : }
455 0 : prepare_to_wait(&journal->j_wait_updates, &wait,
456 : TASK_UNINTERRUPTIBLE);
457 0 : spin_unlock(&transaction->t_handle_lock);
458 0 : spin_unlock(&journal->j_state_lock);
459 0 : schedule();
460 0 : finish_wait(&journal->j_wait_updates, &wait);
461 0 : spin_lock(&journal->j_state_lock);
462 0 : }
463 0 : spin_unlock(&journal->j_state_lock);
464 :
465 : /*
466 : * We have now established a barrier against other normal updates, but
467 : * we also need to barrier against other journal_lock_updates() calls
468 : * to make sure that we serialise special journal-locked operations
469 : * too.
470 : */
471 0 : mutex_lock(&journal->j_barrier);
472 0 : }
473 :
474 : /**
475 : * void journal_unlock_updates (journal_t* journal) - release barrier
476 : * @journal: Journal to release the barrier on.
477 : *
478 : * Release a transaction barrier obtained with journal_lock_updates().
479 : *
480 : * Should be called without the journal lock held.
481 : */
482 : void journal_unlock_updates (journal_t *journal)
483 : {
484 0 : J_ASSERT(journal->j_barrier_count != 0);
485 :
486 0 : mutex_unlock(&journal->j_barrier);
487 0 : spin_lock(&journal->j_state_lock);
488 0 : --journal->j_barrier_count;
489 0 : spin_unlock(&journal->j_state_lock);
490 0 : wake_up(&journal->j_wait_transaction_locked);
491 0 : }
492 :
493 : static void warn_dirty_buffer(struct buffer_head *bh)
494 : {
495 0 : char b[BDEVNAME_SIZE];
496 0 :
497 0 : printk(KERN_WARNING
498 : "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
499 : "There's a risk of filesystem corruption in case of system "
500 : "crash.\n",
501 : bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr);
502 0 : }
503 :
504 : /*
505 : * If the buffer is already part of the current transaction, then there
506 : * is nothing we need to do. If it is already part of a prior
507 : * transaction which we are still committing to disk, then we need to
508 : * make sure that we do not overwrite the old copy: we do copy-out to
509 : * preserve the copy going to disk. We also account the buffer against
510 : * the handle's metadata buffer credits (unless the buffer is already
511 : * part of the transaction, that is).
512 : *
513 : */
514 : static int
515 : do_get_write_access(handle_t *handle, struct journal_head *jh,
516 : int force_copy)
517 0 : {
518 0 : struct buffer_head *bh;
519 0 : transaction_t *transaction;
520 0 : journal_t *journal;
521 0 : int error;
522 0 : char *frozen_buffer = NULL;
523 0 : int need_copy = 0;
524 0 :
525 0 : if (is_handle_aborted(handle))
526 0 : return -EROFS;
527 0 :
528 0 : transaction = handle->h_transaction;
529 0 : journal = transaction->t_journal;
530 0 :
531 0 : jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
532 0 :
533 0 : JBUFFER_TRACE(jh, "entry");
534 0 : repeat:
535 0 : bh = jh2bh(jh);
536 0 :
537 0 : /* @@@ Need to check for errors here at some point. */
538 0 :
539 0 : lock_buffer(bh);
540 0 : jbd_lock_bh_state(bh);
541 0 :
542 0 : /* We now hold the buffer lock so it is safe to query the buffer
543 0 : * state. Is the buffer dirty?
544 0 : *
545 0 : * If so, there are two possibilities. The buffer may be
546 0 : * non-journaled, and undergoing a quite legitimate writeback.
547 0 : * Otherwise, it is journaled, and we don't expect dirty buffers
548 0 : * in that state (the buffers should be marked JBD_Dirty
549 : * instead.) So either the IO is being done under our own
550 : * control and this is a bug, or it's a third party IO such as
551 : * dump(8) (which may leave the buffer scheduled for read ---
552 : * ie. locked but not dirty) or tune2fs (which may actually have
553 : * the buffer dirtied, ugh.) */
554 :
555 0 : if (buffer_dirty(bh)) {
556 : /*
557 : * First question: is this buffer already part of the current
558 : * transaction or the existing committing transaction?
559 : */
560 0 : if (jh->b_transaction) {
561 0 : J_ASSERT_JH(jh,
562 : jh->b_transaction == transaction ||
563 : jh->b_transaction ==
564 : journal->j_committing_transaction);
565 0 : if (jh->b_next_transaction)
566 0 : J_ASSERT_JH(jh, jh->b_next_transaction ==
567 : transaction);
568 0 : warn_dirty_buffer(bh);
569 : }
570 : /*
571 : * In any case we need to clean the dirty flag and we must
572 : * do it under the buffer lock to be sure we don't race
573 : * with running write-out.
574 : */
575 : JBUFFER_TRACE(jh, "Journalling dirty buffer");
576 0 : clear_buffer_dirty(bh);
577 0 : set_buffer_jbddirty(bh);
578 : }
579 :
580 0 : unlock_buffer(bh);
581 :
582 0 : error = -EROFS;
583 0 : if (is_handle_aborted(handle)) {
584 0 : jbd_unlock_bh_state(bh);
585 0 : goto out;
586 : }
587 0 : error = 0;
588 :
589 : /*
590 : * The buffer is already part of this transaction if b_transaction or
591 : * b_next_transaction points to it
592 : */
593 0 : if (jh->b_transaction == transaction ||
594 : jh->b_next_transaction == transaction)
595 0 : goto done;
596 :
597 : /*
598 : * this is the first time this transaction is touching this buffer,
599 : * reset the modified flag
600 : */
601 0 : jh->b_modified = 0;
602 :
603 : /*
604 : * If there is already a copy-out version of this buffer, then we don't
605 : * need to make another one
606 : */
607 0 : if (jh->b_frozen_data) {
608 : JBUFFER_TRACE(jh, "has frozen data");
609 0 : J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
610 0 : jh->b_next_transaction = transaction;
611 0 : goto done;
612 : }
613 :
614 : /* Is there data here we need to preserve? */
615 :
616 0 : if (jh->b_transaction && jh->b_transaction != transaction) {
617 : JBUFFER_TRACE(jh, "owned by older transaction");
618 0 : J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
619 0 : J_ASSERT_JH(jh, jh->b_transaction ==
620 : journal->j_committing_transaction);
621 :
622 : /* There is one case we have to be very careful about.
623 : * If the committing transaction is currently writing
624 : * this buffer out to disk and has NOT made a copy-out,
625 : * then we cannot modify the buffer contents at all
626 : * right now. The essence of copy-out is that it is the
627 : * extra copy, not the primary copy, which gets
628 : * journaled. If the primary copy is already going to
629 : * disk then we cannot do copy-out here. */
630 :
631 0 : if (jh->b_jlist == BJ_Shadow) {
632 0 : DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
633 : wait_queue_head_t *wqh;
634 :
635 0 : wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
636 :
637 : JBUFFER_TRACE(jh, "on shadow: sleep");
638 0 : jbd_unlock_bh_state(bh);
639 : /* commit wakes up all shadow buffers after IO */
640 0 : for ( ; ; ) {
641 0 : prepare_to_wait(wqh, &wait.wait,
642 : TASK_UNINTERRUPTIBLE);
643 0 : if (jh->b_jlist != BJ_Shadow)
644 0 : break;
645 0 : schedule();
646 0 : }
647 0 : finish_wait(wqh, &wait.wait);
648 0 : goto repeat;
649 : }
650 :
651 : /* Only do the copy if the currently-owning transaction
652 : * still needs it. If it is on the Forget list, the
653 : * committing transaction is past that stage. The
654 : * buffer had better remain locked during the kmalloc,
655 : * but that should be true --- we hold the journal lock
656 : * still and the buffer is already on the BUF_JOURNAL
657 : * list so won't be flushed.
658 : *
659 : * Subtle point, though: if this is a get_undo_access,
660 : * then we will be relying on the frozen_data to contain
661 : * the new value of the committed_data record after the
662 : * transaction, so we HAVE to force the frozen_data copy
663 : * in that case. */
664 :
665 0 : if (jh->b_jlist != BJ_Forget || force_copy) {
666 : JBUFFER_TRACE(jh, "generate frozen data");
667 0 : if (!frozen_buffer) {
668 : JBUFFER_TRACE(jh, "allocate memory for buffer");
669 0 : jbd_unlock_bh_state(bh);
670 0 : frozen_buffer =
671 : jbd_alloc(jh2bh(jh)->b_size,
672 : GFP_NOFS);
673 0 : if (!frozen_buffer) {
674 0 : printk(KERN_EMERG
675 : "%s: OOM for frozen_buffer\n",
676 : __func__);
677 : JBUFFER_TRACE(jh, "oom!");
678 0 : error = -ENOMEM;
679 0 : jbd_lock_bh_state(bh);
680 0 : goto done;
681 : }
682 0 : goto repeat;
683 : }
684 0 : jh->b_frozen_data = frozen_buffer;
685 0 : frozen_buffer = NULL;
686 0 : need_copy = 1;
687 : }
688 0 : jh->b_next_transaction = transaction;
689 : }
690 :
691 :
692 : /*
693 : * Finally, if the buffer is not journaled right now, we need to make
694 : * sure it doesn't get written to disk before the caller actually
695 : * commits the new data
696 : */
697 0 : if (!jh->b_transaction) {
698 : JBUFFER_TRACE(jh, "no transaction");
699 0 : J_ASSERT_JH(jh, !jh->b_next_transaction);
700 0 : jh->b_transaction = transaction;
701 : JBUFFER_TRACE(jh, "file as BJ_Reserved");
702 0 : spin_lock(&journal->j_list_lock);
703 0 : __journal_file_buffer(jh, transaction, BJ_Reserved);
704 0 : spin_unlock(&journal->j_list_lock);
705 : }
706 :
707 : done:
708 0 : if (need_copy) {
709 0 : struct page *page;
710 : int offset;
711 : char *source;
712 :
713 0 : J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
714 : "Possible IO failure.\n");
715 0 : page = jh2bh(jh)->b_page;
716 0 : offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
717 0 : source = kmap_atomic(page, KM_USER0);
718 0 : memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
719 0 : kunmap_atomic(source, KM_USER0);
720 : }
721 0 : jbd_unlock_bh_state(bh);
722 :
723 : /*
724 : * If we are about to journal a buffer, then any revoke pending on it is
725 : * no longer valid
726 : */
727 0 : journal_cancel_revoke(handle, jh);
728 :
729 0 : out:
730 0 : if (unlikely(frozen_buffer)) /* It's usually NULL */
731 0 : jbd_free(frozen_buffer, bh->b_size);
732 :
733 : JBUFFER_TRACE(jh, "exit");
734 0 : return error;
735 : }
736 :
737 : /**
738 : * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
739 : * @handle: transaction to add buffer modifications to
740 : * @bh: bh to be used for metadata writes
741 : *
742 : * Returns an error code or 0 on success.
743 : *
744 : * In full data journalling mode the buffer may be of type BJ_AsyncData,
745 : * because we're write()ing a buffer which is also part of a shared mapping.
746 : */
747 :
748 : int journal_get_write_access(handle_t *handle, struct buffer_head *bh)
749 : {
750 0 : struct journal_head *jh = journal_add_journal_head(bh);
751 0 : int rc;
752 0 :
753 : /* We do not want to get caught playing with fields which the
754 : * log thread also manipulates. Make sure that the buffer
755 : * completes any outstanding IO before proceeding. */
756 0 : rc = do_get_write_access(handle, jh, 0);
757 0 : journal_put_journal_head(jh);
758 0 : return rc;
759 : }
760 :
761 :
762 : /*
763 : * When the user wants to journal a newly created buffer_head
764 : * (ie. getblk() returned a new buffer and we are going to populate it
765 : * manually rather than reading off disk), then we need to keep the
766 : * buffer_head locked until it has been completely filled with new
767 : * data. In this case, we should be able to make the assertion that
768 : * the bh is not already part of an existing transaction.
769 : *
770 : * The buffer should already be locked by the caller by this point.
771 : * There is no lock ranking violation: it was a newly created,
772 : * unlocked buffer beforehand. */
773 :
774 : /**
775 : * int journal_get_create_access () - notify intent to use newly created bh
776 : * @handle: transaction to new buffer to
777 : * @bh: new buffer.
778 : *
779 : * Call this if you create a new bh.
780 : */
781 : int journal_get_create_access(handle_t *handle, struct buffer_head *bh)
782 : {
783 0 : transaction_t *transaction = handle->h_transaction;
784 0 : journal_t *journal = transaction->t_journal;
785 0 : struct journal_head *jh = journal_add_journal_head(bh);
786 0 : int err;
787 0 :
788 0 : jbd_debug(5, "journal_head %p\n", jh);
789 0 : err = -EROFS;
790 0 : if (is_handle_aborted(handle))
791 0 : goto out;
792 0 : err = 0;
793 0 :
794 0 : JBUFFER_TRACE(jh, "entry");
795 0 : /*
796 0 : * The buffer may already belong to this transaction due to pre-zeroing
797 0 : * in the filesystem's new_block code. It may also be on the previous,
798 0 : * committing transaction's lists, but it HAS to be in Forget state in
799 0 : * that case: the transaction must have deleted the buffer for it to be
800 : * reused here.
801 : */
802 0 : jbd_lock_bh_state(bh);
803 0 : spin_lock(&journal->j_list_lock);
804 0 : J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
805 : jh->b_transaction == NULL ||
806 : (jh->b_transaction == journal->j_committing_transaction &&
807 : jh->b_jlist == BJ_Forget)));
808 :
809 0 : J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
810 0 : J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
811 :
812 0 : if (jh->b_transaction == NULL) {
813 : /*
814 : * Previous journal_forget() could have left the buffer
815 : * with jbddirty bit set because it was being committed. When
816 : * the commit finished, we've filed the buffer for
817 : * checkpointing and marked it dirty. Now we are reallocating
818 : * the buffer so the transaction freeing it must have
819 : * committed and so it's safe to clear the dirty bit.
820 : */
821 0 : clear_buffer_dirty(jh2bh(jh));
822 0 : jh->b_transaction = transaction;
823 :
824 : /* first access by this transaction */
825 0 : jh->b_modified = 0;
826 :
827 : JBUFFER_TRACE(jh, "file as BJ_Reserved");
828 0 : __journal_file_buffer(jh, transaction, BJ_Reserved);
829 0 : } else if (jh->b_transaction == journal->j_committing_transaction) {
830 : /* first access by this transaction */
831 0 : jh->b_modified = 0;
832 :
833 : JBUFFER_TRACE(jh, "set next transaction");
834 0 : jh->b_next_transaction = transaction;
835 : }
836 0 : spin_unlock(&journal->j_list_lock);
837 0 : jbd_unlock_bh_state(bh);
838 :
839 : /*
840 : * akpm: I added this. ext3_alloc_branch can pick up new indirect
841 : * blocks which contain freed but then revoked metadata. We need
842 : * to cancel the revoke in case we end up freeing it yet again
843 : * and the reallocating as data - this would cause a second revoke,
844 : * which hits an assertion error.
845 : */
846 : JBUFFER_TRACE(jh, "cancelling revoke");
847 0 : journal_cancel_revoke(handle, jh);
848 0 : journal_put_journal_head(jh);
849 : out:
850 0 : return err;
851 : }
852 :
853 : /**
854 : * int journal_get_undo_access() - Notify intent to modify metadata with non-rewindable consequences
855 : * @handle: transaction
856 : * @bh: buffer to undo
857 : *
858 : * Sometimes there is a need to distinguish between metadata which has
859 : * been committed to disk and that which has not. The ext3fs code uses
860 : * this for freeing and allocating space, we have to make sure that we
861 : * do not reuse freed space until the deallocation has been committed,
862 : * since if we overwrote that space we would make the delete
863 : * un-rewindable in case of a crash.
864 : *
865 : * To deal with that, journal_get_undo_access requests write access to a
866 : * buffer for parts of non-rewindable operations such as delete
867 : * operations on the bitmaps. The journaling code must keep a copy of
868 : * the buffer's contents prior to the undo_access call until such time
869 : * as we know that the buffer has definitely been committed to disk.
870 : *
871 : * We never need to know which transaction the committed data is part
872 : * of, buffers touched here are guaranteed to be dirtied later and so
873 : * will be committed to a new transaction in due course, at which point
874 : * we can discard the old committed data pointer.
875 : *
876 : * Returns error number or 0 on success.
877 : */
878 : int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
879 : {
880 0 : int err;
881 0 : struct journal_head *jh = journal_add_journal_head(bh);
882 0 : char *committed_data = NULL;
883 0 :
884 0 : JBUFFER_TRACE(jh, "entry");
885 0 :
886 0 : /*
887 : * Do this first --- it can drop the journal lock, so we want to
888 : * make sure that obtaining the committed_data is done
889 : * atomically wrt. completion of any outstanding commits.
890 : */
891 0 : err = do_get_write_access(handle, jh, 1);
892 0 : if (err)
893 0 : goto out;
894 :
895 : repeat:
896 0 : if (!jh->b_committed_data) {
897 0 : committed_data = jbd_alloc(jh2bh(jh)->b_size, GFP_NOFS);
898 0 : if (!committed_data) {
899 0 : printk(KERN_EMERG "%s: No memory for committed data\n",
900 : __func__);
901 0 : err = -ENOMEM;
902 0 : goto out;
903 : }
904 : }
905 :
906 0 : jbd_lock_bh_state(bh);
907 0 : if (!jh->b_committed_data) {
908 : /* Copy out the current buffer contents into the
909 : * preserved, committed copy. */
910 : JBUFFER_TRACE(jh, "generate b_committed data");
911 0 : if (!committed_data) {
912 0 : jbd_unlock_bh_state(bh);
913 0 : goto repeat;
914 : }
915 :
916 0 : jh->b_committed_data = committed_data;
917 0 : committed_data = NULL;
918 0 : memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
919 : }
920 0 : jbd_unlock_bh_state(bh);
921 : out:
922 0 : journal_put_journal_head(jh);
923 0 : if (unlikely(committed_data))
924 0 : jbd_free(committed_data, bh->b_size);
925 0 : return err;
926 : }
927 :
928 : /**
929 : * int journal_dirty_data() - mark a buffer as containing dirty data to be flushed
930 : * @handle: transaction
931 : * @bh: bufferhead to mark
932 : *
933 : * Description:
934 : * Mark a buffer as containing dirty data which needs to be flushed before
935 : * we can commit the current transaction.
936 : *
937 : * The buffer is placed on the transaction's data list and is marked as
938 : * belonging to the transaction.
939 : *
940 : * Returns error number or 0 on success.
941 : *
942 : * journal_dirty_data() can be called via page_launder->ext3_writepage
943 : * by kswapd.
944 : */
945 : int journal_dirty_data(handle_t *handle, struct buffer_head *bh)
946 : {
947 0 : journal_t *journal = handle->h_transaction->t_journal;
948 0 : int need_brelse = 0;
949 0 : struct journal_head *jh;
950 0 : int ret = 0;
951 0 :
952 0 : if (is_handle_aborted(handle))
953 0 : return ret;
954 0 :
955 0 : jh = journal_add_journal_head(bh);
956 0 : JBUFFER_TRACE(jh, "entry");
957 0 :
958 0 : /*
959 : * The buffer could *already* be dirty. Writeout can start
960 : * at any time.
961 : */
962 : jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
963 :
964 : /*
965 : * What if the buffer is already part of a running transaction?
966 : *
967 : * There are two cases:
968 : * 1) It is part of the current running transaction. Refile it,
969 : * just in case we have allocated it as metadata, deallocated
970 : * it, then reallocated it as data.
971 : * 2) It is part of the previous, still-committing transaction.
972 : * If all we want to do is to guarantee that the buffer will be
973 : * written to disk before this new transaction commits, then
974 : * being sure that the *previous* transaction has this same
975 : * property is sufficient for us! Just leave it on its old
976 : * transaction.
977 : *
978 : * In case (2), the buffer must not already exist as metadata
979 : * --- that would violate write ordering (a transaction is free
980 : * to write its data at any point, even before the previous
981 : * committing transaction has committed). The caller must
982 : * never, ever allow this to happen: there's nothing we can do
983 : * about it in this layer.
984 : */
985 0 : jbd_lock_bh_state(bh);
986 0 : spin_lock(&journal->j_list_lock);
987 :
988 : /* Now that we have bh_state locked, are we really still mapped? */
989 0 : if (!buffer_mapped(bh)) {
990 : JBUFFER_TRACE(jh, "unmapped buffer, bailing out");
991 0 : goto no_journal;
992 : }
993 :
994 0 : if (jh->b_transaction) {
995 : JBUFFER_TRACE(jh, "has transaction");
996 0 : if (jh->b_transaction != handle->h_transaction) {
997 : JBUFFER_TRACE(jh, "belongs to older transaction");
998 0 : J_ASSERT_JH(jh, jh->b_transaction ==
999 : journal->j_committing_transaction);
1000 :
1001 : /* @@@ IS THIS TRUE ? */
1002 : /*
1003 : * Not any more. Scenario: someone does a write()
1004 : * in data=journal mode. The buffer's transaction has
1005 : * moved into commit. Then someone does another
1006 : * write() to the file. We do the frozen data copyout
1007 : * and set b_next_transaction to point to j_running_t.
1008 : * And while we're in that state, someone does a
1009 : * writepage() in an attempt to pageout the same area
1010 : * of the file via a shared mapping. At present that
1011 : * calls journal_dirty_data(), and we get right here.
1012 : * It may be too late to journal the data. Simply
1013 : * falling through to the next test will suffice: the
1014 : * data will be dirty and wil be checkpointed. The
1015 : * ordering comments in the next comment block still
1016 : * apply.
1017 : */
1018 : //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1019 :
1020 : /*
1021 : * If we're journalling data, and this buffer was
1022 : * subject to a write(), it could be metadata, forget
1023 : * or shadow against the committing transaction. Now,
1024 : * someone has dirtied the same darn page via a mapping
1025 : * and it is being writepage()'d.
1026 : * We *could* just steal the page from commit, with some
1027 : * fancy locking there. Instead, we just skip it -
1028 : * don't tie the page's buffers to the new transaction
1029 : * at all.
1030 : * Implication: if we crash before the writepage() data
1031 : * is written into the filesystem, recovery will replay
1032 : * the write() data.
1033 : */
1034 0 : if (jh->b_jlist != BJ_None &&
1035 : jh->b_jlist != BJ_SyncData &&
1036 : jh->b_jlist != BJ_Locked) {
1037 : JBUFFER_TRACE(jh, "Not stealing");
1038 0 : goto no_journal;
1039 : }
1040 :
1041 : /*
1042 : * This buffer may be undergoing writeout in commit. We
1043 : * can't return from here and let the caller dirty it
1044 : * again because that can cause the write-out loop in
1045 : * commit to never terminate.
1046 : */
1047 0 : if (buffer_dirty(bh)) {
1048 0 : get_bh(bh);
1049 0 : spin_unlock(&journal->j_list_lock);
1050 0 : jbd_unlock_bh_state(bh);
1051 0 : need_brelse = 1;
1052 0 : sync_dirty_buffer(bh);
1053 0 : jbd_lock_bh_state(bh);
1054 0 : spin_lock(&journal->j_list_lock);
1055 : /* Since we dropped the lock... */
1056 0 : if (!buffer_mapped(bh)) {
1057 : JBUFFER_TRACE(jh, "buffer got unmapped");
1058 0 : goto no_journal;
1059 : }
1060 : /* The buffer may become locked again at any
1061 : time if it is redirtied */
1062 : }
1063 :
1064 : /*
1065 : * We cannot remove the buffer with io error from the
1066 : * committing transaction, because otherwise it would
1067 : * miss the error and the commit would not abort.
1068 : */
1069 0 : if (unlikely(!buffer_uptodate(bh))) {
1070 0 : ret = -EIO;
1071 0 : goto no_journal;
1072 : }
1073 :
1074 0 : if (jh->b_transaction != NULL) {
1075 : JBUFFER_TRACE(jh, "unfile from commit");
1076 0 : __journal_temp_unlink_buffer(jh);
1077 : /* It still points to the committing
1078 : * transaction; move it to this one so
1079 : * that the refile assert checks are
1080 : * happy. */
1081 0 : jh->b_transaction = handle->h_transaction;
1082 : }
1083 : /* The buffer will be refiled below */
1084 :
1085 : }
1086 : /*
1087 : * Special case --- the buffer might actually have been
1088 : * allocated and then immediately deallocated in the previous,
1089 : * committing transaction, so might still be left on that
1090 : * transaction's metadata lists.
1091 : */
1092 0 : if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
1093 : JBUFFER_TRACE(jh, "not on correct data list: unfile");
1094 0 : J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1095 0 : __journal_temp_unlink_buffer(jh);
1096 0 : jh->b_transaction = handle->h_transaction;
1097 : JBUFFER_TRACE(jh, "file as data");
1098 0 : __journal_file_buffer(jh, handle->h_transaction,
1099 : BJ_SyncData);
1100 : }
1101 : } else {
1102 : JBUFFER_TRACE(jh, "not on a transaction");
1103 0 : __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1104 : }
1105 : no_journal:
1106 0 : spin_unlock(&journal->j_list_lock);
1107 0 : jbd_unlock_bh_state(bh);
1108 0 : if (need_brelse) {
1109 : BUFFER_TRACE(bh, "brelse");
1110 0 : __brelse(bh);
1111 : }
1112 : JBUFFER_TRACE(jh, "exit");
1113 0 : journal_put_journal_head(jh);
1114 0 : return ret;
1115 : }
1116 :
1117 : /**
1118 : * int journal_dirty_metadata() - mark a buffer as containing dirty metadata
1119 : * @handle: transaction to add buffer to.
1120 : * @bh: buffer to mark
1121 : *
1122 : * Mark dirty metadata which needs to be journaled as part of the current
1123 : * transaction.
1124 : *
1125 : * The buffer is placed on the transaction's metadata list and is marked
1126 : * as belonging to the transaction.
1127 : *
1128 : * Returns error number or 0 on success.
1129 : *
1130 : * Special care needs to be taken if the buffer already belongs to the
1131 : * current committing transaction (in which case we should have frozen
1132 : * data present for that commit). In that case, we don't relink the
1133 : * buffer: that only gets done when the old transaction finally
1134 : * completes its commit.
1135 : */
1136 : int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1137 : {
1138 0 : transaction_t *transaction = handle->h_transaction;
1139 0 : journal_t *journal = transaction->t_journal;
1140 0 : struct journal_head *jh = bh2jh(bh);
1141 0 :
1142 0 : jbd_debug(5, "journal_head %p\n", jh);
1143 0 : JBUFFER_TRACE(jh, "entry");
1144 0 : if (is_handle_aborted(handle))
1145 0 : goto out;
1146 0 :
1147 0 : jbd_lock_bh_state(bh);
1148 :
1149 0 : if (jh->b_modified == 0) {
1150 : /*
1151 : * This buffer's got modified and becoming part
1152 : * of the transaction. This needs to be done
1153 : * once a transaction -bzzz
1154 : */
1155 0 : jh->b_modified = 1;
1156 0 : J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1157 0 : handle->h_buffer_credits--;
1158 : }
1159 :
1160 : /*
1161 : * fastpath, to avoid expensive locking. If this buffer is already
1162 : * on the running transaction's metadata list there is nothing to do.
1163 : * Nobody can take it off again because there is a handle open.
1164 : * I _think_ we're OK here with SMP barriers - a mistaken decision will
1165 : * result in this test being false, so we go in and take the locks.
1166 : */
1167 0 : if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1168 : JBUFFER_TRACE(jh, "fastpath");
1169 0 : J_ASSERT_JH(jh, jh->b_transaction ==
1170 : journal->j_running_transaction);
1171 0 : goto out_unlock_bh;
1172 : }
1173 :
1174 0 : set_buffer_jbddirty(bh);
1175 :
1176 : /*
1177 : * Metadata already on the current transaction list doesn't
1178 : * need to be filed. Metadata on another transaction's list must
1179 : * be committing, and will be refiled once the commit completes:
1180 : * leave it alone for now.
1181 : */
1182 0 : if (jh->b_transaction != transaction) {
1183 : JBUFFER_TRACE(jh, "already on other transaction");
1184 0 : J_ASSERT_JH(jh, jh->b_transaction ==
1185 : journal->j_committing_transaction);
1186 0 : J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1187 : /* And this case is illegal: we can't reuse another
1188 : * transaction's data buffer, ever. */
1189 0 : goto out_unlock_bh;
1190 : }
1191 :
1192 : /* That test should have eliminated the following case: */
1193 0 : J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
1194 :
1195 : JBUFFER_TRACE(jh, "file as BJ_Metadata");
1196 0 : spin_lock(&journal->j_list_lock);
1197 0 : __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1198 0 : spin_unlock(&journal->j_list_lock);
1199 : out_unlock_bh:
1200 0 : jbd_unlock_bh_state(bh);
1201 : out:
1202 0 : JBUFFER_TRACE(jh, "exit");
1203 0 : return 0;
1204 : }
1205 :
1206 : /*
1207 : * journal_release_buffer: undo a get_write_access without any buffer
1208 : * updates, if the update decided in the end that it didn't need access.
1209 : *
1210 : */
1211 : void
1212 : journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1213 : {
1214 0 : BUFFER_TRACE(bh, "entry");
1215 : }
1216 :
1217 : /**
1218 : * void journal_forget() - bforget() for potentially-journaled buffers.
1219 : * @handle: transaction handle
1220 : * @bh: bh to 'forget'
1221 : *
1222 : * We can only do the bforget if there are no commits pending against the
1223 : * buffer. If the buffer is dirty in the current running transaction we
1224 : * can safely unlink it.
1225 : *
1226 : * bh may not be a journalled buffer at all - it may be a non-JBD
1227 : * buffer which came off the hashtable. Check for this.
1228 : *
1229 : * Decrements bh->b_count by one.
1230 : *
1231 : * Allow this call even if the handle has aborted --- it may be part of
1232 : * the caller's cleanup after an abort.
1233 : */
1234 : int journal_forget (handle_t *handle, struct buffer_head *bh)
1235 : {
1236 0 : transaction_t *transaction = handle->h_transaction;
1237 0 : journal_t *journal = transaction->t_journal;
1238 0 : struct journal_head *jh;
1239 0 : int drop_reserve = 0;
1240 0 : int err = 0;
1241 0 : int was_modified = 0;
1242 0 :
1243 0 : BUFFER_TRACE(bh, "entry");
1244 0 :
1245 0 : jbd_lock_bh_state(bh);
1246 0 : spin_lock(&journal->j_list_lock);
1247 0 :
1248 0 : if (!buffer_jbd(bh))
1249 0 : goto not_jbd;
1250 0 : jh = bh2jh(bh);
1251 :
1252 : /* Critical error: attempting to delete a bitmap buffer, maybe?
1253 : * Don't do any jbd operations, and return an error. */
1254 0 : if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1255 : "inconsistent data on disk")) {
1256 0 : err = -EIO;
1257 0 : goto not_jbd;
1258 : }
1259 :
1260 : /* keep track of wether or not this transaction modified us */
1261 0 : was_modified = jh->b_modified;
1262 :
1263 : /*
1264 : * The buffer's going from the transaction, we must drop
1265 : * all references -bzzz
1266 : */
1267 0 : jh->b_modified = 0;
1268 :
1269 0 : if (jh->b_transaction == handle->h_transaction) {
1270 0 : J_ASSERT_JH(jh, !jh->b_frozen_data);
1271 :
1272 : /* If we are forgetting a buffer which is already part
1273 : * of this transaction, then we can just drop it from
1274 : * the transaction immediately. */
1275 0 : clear_buffer_dirty(bh);
1276 0 : clear_buffer_jbddirty(bh);
1277 :
1278 : JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1279 :
1280 : /*
1281 : * we only want to drop a reference if this transaction
1282 : * modified the buffer
1283 : */
1284 0 : if (was_modified)
1285 0 : drop_reserve = 1;
1286 :
1287 : /*
1288 : * We are no longer going to journal this buffer.
1289 : * However, the commit of this transaction is still
1290 : * important to the buffer: the delete that we are now
1291 : * processing might obsolete an old log entry, so by
1292 : * committing, we can satisfy the buffer's checkpoint.
1293 : *
1294 : * So, if we have a checkpoint on the buffer, we should
1295 : * now refile the buffer on our BJ_Forget list so that
1296 : * we know to remove the checkpoint after we commit.
1297 : */
1298 :
1299 0 : if (jh->b_cp_transaction) {
1300 0 : __journal_temp_unlink_buffer(jh);
1301 0 : __journal_file_buffer(jh, transaction, BJ_Forget);
1302 : } else {
1303 0 : __journal_unfile_buffer(jh);
1304 0 : journal_remove_journal_head(bh);
1305 0 : __brelse(bh);
1306 0 : if (!buffer_jbd(bh)) {
1307 0 : spin_unlock(&journal->j_list_lock);
1308 0 : jbd_unlock_bh_state(bh);
1309 0 : __bforget(bh);
1310 0 : goto drop;
1311 : }
1312 : }
1313 0 : } else if (jh->b_transaction) {
1314 0 : J_ASSERT_JH(jh, (jh->b_transaction ==
1315 : journal->j_committing_transaction));
1316 : /* However, if the buffer is still owned by a prior
1317 : * (committing) transaction, we can't drop it yet... */
1318 : JBUFFER_TRACE(jh, "belongs to older transaction");
1319 : /* ... but we CAN drop it from the new transaction if we
1320 : * have also modified it since the original commit. */
1321 :
1322 0 : if (jh->b_next_transaction) {
1323 0 : J_ASSERT(jh->b_next_transaction == transaction);
1324 0 : jh->b_next_transaction = NULL;
1325 :
1326 : /*
1327 : * only drop a reference if this transaction modified
1328 : * the buffer
1329 : */
1330 0 : if (was_modified)
1331 0 : drop_reserve = 1;
1332 : }
1333 : }
1334 :
1335 : not_jbd:
1336 0 : spin_unlock(&journal->j_list_lock);
1337 0 : jbd_unlock_bh_state(bh);
1338 0 : __brelse(bh);
1339 : drop:
1340 0 : if (drop_reserve) {
1341 0 : /* no need to reserve log space for this block -bzzz */
1342 0 : handle->h_buffer_credits++;
1343 : }
1344 0 : return err;
1345 : }
1346 :
1347 : /**
1348 : * int journal_stop() - complete a transaction
1349 : * @handle: tranaction to complete.
1350 : *
1351 : * All done for a particular handle.
1352 : *
1353 : * There is not much action needed here. We just return any remaining
1354 : * buffer credits to the transaction and remove the handle. The only
1355 : * complication is that we need to start a commit operation if the
1356 : * filesystem is marked for synchronous update.
1357 : *
1358 : * journal_stop itself will not usually return an error, but it may
1359 : * do so in unusual circumstances. In particular, expect it to
1360 : * return -EIO if a journal_abort has been executed since the
1361 : * transaction began.
1362 : */
1363 : int journal_stop(handle_t *handle)
1364 : {
1365 0 : transaction_t *transaction = handle->h_transaction;
1366 0 : journal_t *journal = transaction->t_journal;
1367 0 : int err;
1368 0 : pid_t pid;
1369 0 :
1370 0 : J_ASSERT(journal_current_handle() == handle);
1371 0 :
1372 0 : if (is_handle_aborted(handle))
1373 0 : err = -EIO;
1374 0 : else {
1375 0 : J_ASSERT(transaction->t_updates > 0);
1376 0 : err = 0;
1377 0 : }
1378 0 :
1379 0 : if (--handle->h_ref > 0) {
1380 0 : jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1381 0 : handle->h_ref);
1382 0 : return err;
1383 0 : }
1384 0 :
1385 0 : jbd_debug(4, "Handle %p going down\n", handle);
1386 0 :
1387 0 : /*
1388 0 : * Implement synchronous transaction batching. If the handle
1389 0 : * was synchronous, don't force a commit immediately. Let's
1390 0 : * yield and let another thread piggyback onto this transaction.
1391 : * Keep doing that while new threads continue to arrive.
1392 : * It doesn't cost much - we're about to run a commit and sleep
1393 : * on IO anyway. Speeds up many-threaded, many-dir operations
1394 : * by 30x or more...
1395 : *
1396 : * We try and optimize the sleep time against what the underlying disk
1397 : * can do, instead of having a static sleep time. This is usefull for
1398 : * the case where our storage is so fast that it is more optimal to go
1399 : * ahead and force a flush and wait for the transaction to be committed
1400 : * than it is to wait for an arbitrary amount of time for new writers to
1401 : * join the transaction. We acheive this by measuring how long it takes
1402 : * to commit a transaction, and compare it with how long this
1403 : * transaction has been running, and if run time < commit time then we
1404 : * sleep for the delta and commit. This greatly helps super fast disks
1405 : * that would see slowdowns as more threads started doing fsyncs.
1406 : *
1407 : * But don't do this if this process was the most recent one to
1408 : * perform a synchronous write. We do this to detect the case where a
1409 : * single process is doing a stream of sync writes. No point in waiting
1410 : * for joiners in that case.
1411 : */
1412 0 : pid = current->pid;
1413 0 : if (handle->h_sync && journal->j_last_sync_writer != pid) {
1414 : u64 commit_time, trans_time;
1415 :
1416 0 : journal->j_last_sync_writer = pid;
1417 :
1418 0 : spin_lock(&journal->j_state_lock);
1419 0 : commit_time = journal->j_average_commit_time;
1420 0 : spin_unlock(&journal->j_state_lock);
1421 :
1422 0 : trans_time = ktime_to_ns(ktime_sub(ktime_get(),
1423 : transaction->t_start_time));
1424 :
1425 0 : commit_time = min_t(u64, commit_time,
1426 : 1000*jiffies_to_usecs(1));
1427 :
1428 0 : if (trans_time < commit_time) {
1429 0 : ktime_t expires = ktime_add_ns(ktime_get(),
1430 : commit_time);
1431 0 : set_current_state(TASK_UNINTERRUPTIBLE);
1432 0 : schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
1433 : }
1434 : }
1435 :
1436 0 : if (handle->h_sync)
1437 0 : transaction->t_synchronous_commit = 1;
1438 0 : current->journal_info = NULL;
1439 0 : spin_lock(&journal->j_state_lock);
1440 0 : spin_lock(&transaction->t_handle_lock);
1441 0 : transaction->t_outstanding_credits -= handle->h_buffer_credits;
1442 0 : transaction->t_updates--;
1443 0 : if (!transaction->t_updates) {
1444 0 : wake_up(&journal->j_wait_updates);
1445 0 : if (journal->j_barrier_count)
1446 0 : wake_up(&journal->j_wait_transaction_locked);
1447 : }
1448 :
1449 : /*
1450 : * If the handle is marked SYNC, we need to set another commit
1451 : * going! We also want to force a commit if the current
1452 : * transaction is occupying too much of the log, or if the
1453 : * transaction is too old now.
1454 : */
1455 : if (handle->h_sync ||
1456 : transaction->t_outstanding_credits >
1457 : journal->j_max_transaction_buffers ||
1458 0 : time_after_eq(jiffies, transaction->t_expires)) {
1459 : /* Do this even for aborted journals: an abort still
1460 : * completes the commit thread, it just doesn't write
1461 : * anything to disk. */
1462 0 : tid_t tid = transaction->t_tid;
1463 :
1464 0 : spin_unlock(&transaction->t_handle_lock);
1465 : jbd_debug(2, "transaction too old, requesting commit for "
1466 : "handle %p\n", handle);
1467 : /* This is non-blocking */
1468 0 : __log_start_commit(journal, transaction->t_tid);
1469 0 : spin_unlock(&journal->j_state_lock);
1470 :
1471 : /*
1472 : * Special case: JFS_SYNC synchronous updates require us
1473 : * to wait for the commit to complete.
1474 : */
1475 0 : if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1476 0 : err = log_wait_commit(journal, tid);
1477 : } else {
1478 0 : spin_unlock(&transaction->t_handle_lock);
1479 0 : spin_unlock(&journal->j_state_lock);
1480 : }
1481 :
1482 : lock_map_release(&handle->h_lockdep_map);
1483 :
1484 0 : jbd_free_handle(handle);
1485 0 : return err;
1486 : }
1487 :
1488 : /**
1489 : * int journal_force_commit() - force any uncommitted transactions
1490 : * @journal: journal to force
1491 : *
1492 : * For synchronous operations: force any uncommitted transactions
1493 : * to disk. May seem kludgy, but it reuses all the handle batching
1494 : * code in a very simple manner.
1495 : */
1496 : int journal_force_commit(journal_t *journal)
1497 : {
1498 0 : handle_t *handle;
1499 0 : int ret;
1500 0 :
1501 0 : handle = journal_start(journal, 1);
1502 0 : if (IS_ERR(handle)) {
1503 0 : ret = PTR_ERR(handle);
1504 : } else {
1505 0 : handle->h_sync = 1;
1506 0 : ret = journal_stop(handle);
1507 : }
1508 0 : return ret;
1509 : }
1510 :
1511 : /*
1512 : *
1513 : * List management code snippets: various functions for manipulating the
1514 : * transaction buffer lists.
1515 : *
1516 : */
1517 :
1518 : /*
1519 : * Append a buffer to a transaction list, given the transaction's list head
1520 : * pointer.
1521 : *
1522 : * j_list_lock is held.
1523 : *
1524 : * jbd_lock_bh_state(jh2bh(jh)) is held.
1525 : */
1526 :
1527 : static inline void
1528 : __blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1529 : {
1530 0 : if (!*list) {
1531 0 : jh->b_tnext = jh->b_tprev = jh;
1532 0 : *list = jh;
1533 0 : } else {
1534 : /* Insert at the tail of the list to preserve order */
1535 0 : struct journal_head *first = *list, *last = first->b_tprev;
1536 0 : jh->b_tprev = last;
1537 0 : jh->b_tnext = first;
1538 0 : last->b_tnext = first->b_tprev = jh;
1539 : }
1540 0 : }
1541 :
1542 : /*
1543 : * Remove a buffer from a transaction list, given the transaction's list
1544 : * head pointer.
1545 : *
1546 : * Called with j_list_lock held, and the journal may not be locked.
1547 : *
1548 : * jbd_lock_bh_state(jh2bh(jh)) is held.
1549 : */
1550 :
1551 : static inline void
1552 : __blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1553 : {
1554 0 : if (*list == jh) {
1555 0 : *list = jh->b_tnext;
1556 0 : if (*list == jh)
1557 0 : *list = NULL;
1558 : }
1559 0 : jh->b_tprev->b_tnext = jh->b_tnext;
1560 0 : jh->b_tnext->b_tprev = jh->b_tprev;
1561 0 : }
1562 :
1563 : /*
1564 : * Remove a buffer from the appropriate transaction list.
1565 : *
1566 : * Note that this function can *change* the value of
1567 : * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1568 : * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller
1569 : * is holding onto a copy of one of thee pointers, it could go bad.
1570 : * Generally the caller needs to re-read the pointer from the transaction_t.
1571 : *
1572 : * Called under j_list_lock. The journal may not be locked.
1573 : */
1574 : static void __journal_temp_unlink_buffer(struct journal_head *jh)
1575 : {
1576 0 : struct journal_head **list = NULL;
1577 0 : transaction_t *transaction;
1578 0 : struct buffer_head *bh = jh2bh(jh);
1579 0 :
1580 0 : J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1581 0 : transaction = jh->b_transaction;
1582 0 : if (transaction)
1583 0 : assert_spin_locked(&transaction->t_journal->j_list_lock);
1584 0 :
1585 0 : J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1586 0 : if (jh->b_jlist != BJ_None)
1587 0 : J_ASSERT_JH(jh, transaction != NULL);
1588 :
1589 0 : switch (jh->b_jlist) {
1590 0 : case BJ_None:
1591 0 : return;
1592 0 : case BJ_SyncData:
1593 0 : list = &transaction->t_sync_datalist;
1594 0 : break;
1595 0 : case BJ_Metadata:
1596 0 : transaction->t_nr_buffers--;
1597 0 : J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1598 0 : list = &transaction->t_buffers;
1599 0 : break;
1600 0 : case BJ_Forget:
1601 0 : list = &transaction->t_forget;
1602 0 : break;
1603 0 : case BJ_IO:
1604 0 : list = &transaction->t_iobuf_list;
1605 0 : break;
1606 0 : case BJ_Shadow:
1607 0 : list = &transaction->t_shadow_list;
1608 0 : break;
1609 0 : case BJ_LogCtl:
1610 0 : list = &transaction->t_log_list;
1611 0 : break;
1612 0 : case BJ_Reserved:
1613 0 : list = &transaction->t_reserved_list;
1614 0 : break;
1615 0 : case BJ_Locked:
1616 0 : list = &transaction->t_locked_list;
1617 0 : break;
1618 0 : }
1619 :
1620 0 : __blist_del_buffer(list, jh);
1621 0 : jh->b_jlist = BJ_None;
1622 0 : if (test_clear_buffer_jbddirty(bh))
1623 0 : mark_buffer_dirty(bh); /* Expose it to the VM */
1624 0 : }
1625 :
1626 : void __journal_unfile_buffer(struct journal_head *jh)
1627 : {
1628 0 : __journal_temp_unlink_buffer(jh);
1629 0 : jh->b_transaction = NULL;
1630 0 : }
1631 :
1632 : void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1633 : {
1634 0 : jbd_lock_bh_state(jh2bh(jh));
1635 0 : spin_lock(&journal->j_list_lock);
1636 0 : __journal_unfile_buffer(jh);
1637 0 : spin_unlock(&journal->j_list_lock);
1638 0 : jbd_unlock_bh_state(jh2bh(jh));
1639 0 : }
1640 :
1641 : /*
1642 : * Called from journal_try_to_free_buffers().
1643 : *
1644 : * Called under jbd_lock_bh_state(bh)
1645 : */
1646 : static void
1647 : __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1648 : {
1649 0 : struct journal_head *jh;
1650 0 :
1651 0 : jh = bh2jh(bh);
1652 :
1653 0 : if (buffer_locked(bh) || buffer_dirty(bh))
1654 0 : goto out;
1655 :
1656 0 : if (jh->b_next_transaction != NULL)
1657 0 : goto out;
1658 :
1659 0 : spin_lock(&journal->j_list_lock);
1660 0 : if (jh->b_transaction != NULL && jh->b_cp_transaction == NULL) {
1661 0 : if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1662 : /* A written-back ordered data buffer */
1663 : JBUFFER_TRACE(jh, "release data");
1664 0 : __journal_unfile_buffer(jh);
1665 0 : journal_remove_journal_head(bh);
1666 0 : __brelse(bh);
1667 : }
1668 0 : } else if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
1669 : /* written-back checkpointed metadata buffer */
1670 0 : if (jh->b_jlist == BJ_None) {
1671 : JBUFFER_TRACE(jh, "remove from checkpoint list");
1672 0 : __journal_remove_checkpoint(jh);
1673 0 : journal_remove_journal_head(bh);
1674 0 : __brelse(bh);
1675 : }
1676 : }
1677 0 : spin_unlock(&journal->j_list_lock);
1678 : out:
1679 0 : return;
1680 : }
1681 :
1682 : /**
1683 : * int journal_try_to_free_buffers() - try to free page buffers.
1684 : * @journal: journal for operation
1685 : * @page: to try and free
1686 : * @gfp_mask: we use the mask to detect how hard should we try to release
1687 : * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
1688 : * release the buffers.
1689 : *
1690 : *
1691 : * For all the buffers on this page,
1692 : * if they are fully written out ordered data, move them onto BUF_CLEAN
1693 : * so try_to_free_buffers() can reap them.
1694 : *
1695 : * This function returns non-zero if we wish try_to_free_buffers()
1696 : * to be called. We do this if the page is releasable by try_to_free_buffers().
1697 : * We also do it if the page has locked or dirty buffers and the caller wants
1698 : * us to perform sync or async writeout.
1699 : *
1700 : * This complicates JBD locking somewhat. We aren't protected by the
1701 : * BKL here. We wish to remove the buffer from its committing or
1702 : * running transaction's ->t_datalist via __journal_unfile_buffer.
1703 : *
1704 : * This may *change* the value of transaction_t->t_datalist, so anyone
1705 : * who looks at t_datalist needs to lock against this function.
1706 : *
1707 : * Even worse, someone may be doing a journal_dirty_data on this
1708 : * buffer. So we need to lock against that. journal_dirty_data()
1709 : * will come out of the lock with the buffer dirty, which makes it
1710 : * ineligible for release here.
1711 : *
1712 : * Who else is affected by this? hmm... Really the only contender
1713 : * is do_get_write_access() - it could be looking at the buffer while
1714 : * journal_try_to_free_buffer() is changing its state. But that
1715 : * cannot happen because we never reallocate freed data as metadata
1716 : * while the data is part of a transaction. Yes?
1717 : *
1718 : * Return 0 on failure, 1 on success
1719 : */
1720 : int journal_try_to_free_buffers(journal_t *journal,
1721 : struct page *page, gfp_t gfp_mask)
1722 0 : {
1723 0 : struct buffer_head *head;
1724 0 : struct buffer_head *bh;
1725 0 : int ret = 0;
1726 0 :
1727 0 : J_ASSERT(PageLocked(page));
1728 0 :
1729 0 : head = page_buffers(page);
1730 0 : bh = head;
1731 0 : do {
1732 : struct journal_head *jh;
1733 :
1734 : /*
1735 : * We take our own ref against the journal_head here to avoid
1736 : * having to add tons of locking around each instance of
1737 : * journal_remove_journal_head() and journal_put_journal_head().
1738 : */
1739 0 : jh = journal_grab_journal_head(bh);
1740 0 : if (!jh)
1741 0 : continue;
1742 :
1743 0 : jbd_lock_bh_state(bh);
1744 0 : __journal_try_to_free_buffer(journal, bh);
1745 0 : journal_put_journal_head(jh);
1746 0 : jbd_unlock_bh_state(bh);
1747 0 : if (buffer_jbd(bh))
1748 0 : goto busy;
1749 0 : } while ((bh = bh->b_this_page) != head);
1750 :
1751 0 : ret = try_to_free_buffers(page);
1752 0 :
1753 0 : busy:
1754 0 : return ret;
1755 : }
1756 :
1757 : /*
1758 : * This buffer is no longer needed. If it is on an older transaction's
1759 : * checkpoint list we need to record it on this transaction's forget list
1760 : * to pin this buffer (and hence its checkpointing transaction) down until
1761 : * this transaction commits. If the buffer isn't on a checkpoint list, we
1762 : * release it.
1763 : * Returns non-zero if JBD no longer has an interest in the buffer.
1764 : *
1765 : * Called under j_list_lock.
1766 : *
1767 : * Called under jbd_lock_bh_state(bh).
1768 : */
1769 : static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1770 : {
1771 0 : int may_free = 1;
1772 0 : struct buffer_head *bh = jh2bh(jh);
1773 0 :
1774 0 : __journal_unfile_buffer(jh);
1775 :
1776 0 : if (jh->b_cp_transaction) {
1777 : JBUFFER_TRACE(jh, "on running+cp transaction");
1778 : /*
1779 : * We don't want to write the buffer anymore, clear the
1780 : * bit so that we don't confuse checks in
1781 : * __journal_file_buffer
1782 : */
1783 0 : clear_buffer_dirty(bh);
1784 0 : __journal_file_buffer(jh, transaction, BJ_Forget);
1785 0 : may_free = 0;
1786 : } else {
1787 : JBUFFER_TRACE(jh, "on running transaction");
1788 0 : journal_remove_journal_head(bh);
1789 0 : __brelse(bh);
1790 : }
1791 0 : return may_free;
1792 : }
1793 :
1794 : /*
1795 : * journal_invalidatepage
1796 : *
1797 : * This code is tricky. It has a number of cases to deal with.
1798 : *
1799 : * There are two invariants which this code relies on:
1800 : *
1801 : * i_size must be updated on disk before we start calling invalidatepage on the
1802 : * data.
1803 : *
1804 : * This is done in ext3 by defining an ext3_setattr method which
1805 : * updates i_size before truncate gets going. By maintaining this
1806 : * invariant, we can be sure that it is safe to throw away any buffers
1807 : * attached to the current transaction: once the transaction commits,
1808 : * we know that the data will not be needed.
1809 : *
1810 : * Note however that we can *not* throw away data belonging to the
1811 : * previous, committing transaction!
1812 : *
1813 : * Any disk blocks which *are* part of the previous, committing
1814 : * transaction (and which therefore cannot be discarded immediately) are
1815 : * not going to be reused in the new running transaction
1816 : *
1817 : * The bitmap committed_data images guarantee this: any block which is
1818 : * allocated in one transaction and removed in the next will be marked
1819 : * as in-use in the committed_data bitmap, so cannot be reused until
1820 : * the next transaction to delete the block commits. This means that
1821 : * leaving committing buffers dirty is quite safe: the disk blocks
1822 : * cannot be reallocated to a different file and so buffer aliasing is
1823 : * not possible.
1824 : *
1825 : *
1826 : * The above applies mainly to ordered data mode. In writeback mode we
1827 : * don't make guarantees about the order in which data hits disk --- in
1828 : * particular we don't guarantee that new dirty data is flushed before
1829 : * transaction commit --- so it is always safe just to discard data
1830 : * immediately in that mode. --sct
1831 : */
1832 :
1833 : /*
1834 : * The journal_unmap_buffer helper function returns zero if the buffer
1835 : * concerned remains pinned as an anonymous buffer belonging to an older
1836 : * transaction.
1837 : *
1838 : * We're outside-transaction here. Either or both of j_running_transaction
1839 : * and j_committing_transaction may be NULL.
1840 : */
1841 : static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1842 : {
1843 0 : transaction_t *transaction;
1844 0 : struct journal_head *jh;
1845 0 : int may_free = 1;
1846 0 : int ret;
1847 0 :
1848 0 : BUFFER_TRACE(bh, "entry");
1849 0 :
1850 0 : /*
1851 0 : * It is safe to proceed here without the j_list_lock because the
1852 0 : * buffers cannot be stolen by try_to_free_buffers as long as we are
1853 : * holding the page lock. --sct
1854 : */
1855 :
1856 0 : if (!buffer_jbd(bh))
1857 0 : goto zap_buffer_unlocked;
1858 :
1859 0 : spin_lock(&journal->j_state_lock);
1860 0 : jbd_lock_bh_state(bh);
1861 0 : spin_lock(&journal->j_list_lock);
1862 :
1863 0 : jh = journal_grab_journal_head(bh);
1864 0 : if (!jh)
1865 0 : goto zap_buffer_no_jh;
1866 :
1867 0 : transaction = jh->b_transaction;
1868 0 : if (transaction == NULL) {
1869 : /* First case: not on any transaction. If it
1870 : * has no checkpoint link, then we can zap it:
1871 : * it's a writeback-mode buffer so we don't care
1872 : * if it hits disk safely. */
1873 0 : if (!jh->b_cp_transaction) {
1874 : JBUFFER_TRACE(jh, "not on any transaction: zap");
1875 0 : goto zap_buffer;
1876 : }
1877 :
1878 0 : if (!buffer_dirty(bh)) {
1879 : /* bdflush has written it. We can drop it now */
1880 0 : goto zap_buffer;
1881 : }
1882 :
1883 : /* OK, it must be in the journal but still not
1884 : * written fully to disk: it's metadata or
1885 : * journaled data... */
1886 :
1887 0 : if (journal->j_running_transaction) {
1888 : /* ... and once the current transaction has
1889 : * committed, the buffer won't be needed any
1890 : * longer. */
1891 : JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1892 0 : ret = __dispose_buffer(jh,
1893 : journal->j_running_transaction);
1894 0 : journal_put_journal_head(jh);
1895 0 : spin_unlock(&journal->j_list_lock);
1896 0 : jbd_unlock_bh_state(bh);
1897 0 : spin_unlock(&journal->j_state_lock);
1898 0 : return ret;
1899 : } else {
1900 : /* There is no currently-running transaction. So the
1901 : * orphan record which we wrote for this file must have
1902 : * passed into commit. We must attach this buffer to
1903 : * the committing transaction, if it exists. */
1904 0 : if (journal->j_committing_transaction) {
1905 : JBUFFER_TRACE(jh, "give to committing trans");
1906 0 : ret = __dispose_buffer(jh,
1907 : journal->j_committing_transaction);
1908 0 : journal_put_journal_head(jh);
1909 0 : spin_unlock(&journal->j_list_lock);
1910 0 : jbd_unlock_bh_state(bh);
1911 0 : spin_unlock(&journal->j_state_lock);
1912 0 : return ret;
1913 : } else {
1914 : /* The orphan record's transaction has
1915 : * committed. We can cleanse this buffer */
1916 0 : clear_buffer_jbddirty(bh);
1917 0 : goto zap_buffer;
1918 : }
1919 : }
1920 0 : } else if (transaction == journal->j_committing_transaction) {
1921 : JBUFFER_TRACE(jh, "on committing transaction");
1922 0 : if (jh->b_jlist == BJ_Locked) {
1923 : /*
1924 : * The buffer is on the committing transaction's locked
1925 : * list. We have the buffer locked, so I/O has
1926 : * completed. So we can nail the buffer now.
1927 : */
1928 0 : may_free = __dispose_buffer(jh, transaction);
1929 0 : goto zap_buffer;
1930 : }
1931 : /*
1932 : * If it is committing, we simply cannot touch it. We
1933 : * can remove it's next_transaction pointer from the
1934 : * running transaction if that is set, but nothing
1935 : * else. */
1936 0 : set_buffer_freed(bh);
1937 0 : if (jh->b_next_transaction) {
1938 0 : J_ASSERT(jh->b_next_transaction ==
1939 : journal->j_running_transaction);
1940 0 : jh->b_next_transaction = NULL;
1941 : }
1942 0 : journal_put_journal_head(jh);
1943 0 : spin_unlock(&journal->j_list_lock);
1944 0 : jbd_unlock_bh_state(bh);
1945 0 : spin_unlock(&journal->j_state_lock);
1946 0 : return 0;
1947 : } else {
1948 : /* Good, the buffer belongs to the running transaction.
1949 : * We are writing our own transaction's data, not any
1950 : * previous one's, so it is safe to throw it away
1951 : * (remember that we expect the filesystem to have set
1952 : * i_size already for this truncate so recovery will not
1953 : * expose the disk blocks we are discarding here.) */
1954 0 : J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1955 : JBUFFER_TRACE(jh, "on running transaction");
1956 0 : may_free = __dispose_buffer(jh, transaction);
1957 : }
1958 :
1959 0 : zap_buffer:
1960 0 : journal_put_journal_head(jh);
1961 : zap_buffer_no_jh:
1962 0 : spin_unlock(&journal->j_list_lock);
1963 0 : jbd_unlock_bh_state(bh);
1964 0 : spin_unlock(&journal->j_state_lock);
1965 : zap_buffer_unlocked:
1966 0 : clear_buffer_dirty(bh);
1967 0 : J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1968 0 : clear_buffer_mapped(bh);
1969 0 : clear_buffer_req(bh);
1970 0 : clear_buffer_new(bh);
1971 0 : bh->b_bdev = NULL;
1972 0 : return may_free;
1973 : }
1974 :
1975 : /**
1976 : * void journal_invalidatepage() - invalidate a journal page
1977 : * @journal: journal to use for flush
1978 : * @page: page to flush
1979 : * @offset: length of page to invalidate.
1980 : *
1981 : * Reap page buffers containing data after offset in page.
1982 : */
1983 : void journal_invalidatepage(journal_t *journal,
1984 : struct page *page,
1985 0 : unsigned long offset)
1986 0 : {
1987 0 : struct buffer_head *head, *bh, *next;
1988 0 : unsigned int curr_off = 0;
1989 0 : int may_free = 1;
1990 0 :
1991 0 : if (!PageLocked(page))
1992 0 : BUG();
1993 0 : if (!page_has_buffers(page))
1994 0 : return;
1995 0 :
1996 0 : /* We will potentially be playing with lists other than just the
1997 0 : * data lists (especially for journaled data mode), so be
1998 0 : * cautious in our locking. */
1999 :
2000 0 : head = bh = page_buffers(page);
2001 0 : do {
2002 0 : unsigned int next_off = curr_off + bh->b_size;
2003 0 : next = bh->b_this_page;
2004 :
2005 0 : if (offset <= curr_off) {
2006 : /* This block is wholly outside the truncation point */
2007 0 : lock_buffer(bh);
2008 0 : may_free &= journal_unmap_buffer(journal, bh);
2009 0 : unlock_buffer(bh);
2010 : }
2011 0 : curr_off = next_off;
2012 0 : bh = next;
2013 :
2014 0 : } while (bh != head);
2015 :
2016 0 : if (!offset) {
2017 0 : if (may_free && try_to_free_buffers(page))
2018 0 : J_ASSERT(!page_has_buffers(page));
2019 : }
2020 0 : }
2021 :
2022 : /*
2023 : * File a buffer on the given transaction list.
2024 : */
2025 : void __journal_file_buffer(struct journal_head *jh,
2026 : transaction_t *transaction, int jlist)
2027 : {
2028 0 : struct journal_head **list = NULL;
2029 0 : int was_dirty = 0;
2030 0 : struct buffer_head *bh = jh2bh(jh);
2031 0 :
2032 0 : J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2033 0 : assert_spin_locked(&transaction->t_journal->j_list_lock);
2034 0 :
2035 0 : J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
2036 0 : J_ASSERT_JH(jh, jh->b_transaction == transaction ||
2037 0 : jh->b_transaction == NULL);
2038 0 :
2039 0 : if (jh->b_transaction && jh->b_jlist == jlist)
2040 0 : return;
2041 0 :
2042 0 : if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
2043 : jlist == BJ_Shadow || jlist == BJ_Forget) {
2044 : /*
2045 : * For metadata buffers, we track dirty bit in buffer_jbddirty
2046 : * instead of buffer_dirty. We should not see a dirty bit set
2047 : * here because we clear it in do_get_write_access but e.g.
2048 : * tune2fs can modify the sb and set the dirty bit at any time
2049 : * so we try to gracefully handle that.
2050 : */
2051 0 : if (buffer_dirty(bh))
2052 0 : warn_dirty_buffer(bh);
2053 0 : if (test_clear_buffer_dirty(bh) ||
2054 : test_clear_buffer_jbddirty(bh))
2055 0 : was_dirty = 1;
2056 : }
2057 :
2058 0 : if (jh->b_transaction)
2059 0 : __journal_temp_unlink_buffer(jh);
2060 0 : jh->b_transaction = transaction;
2061 :
2062 0 : switch (jlist) {
2063 0 : case BJ_None:
2064 0 : J_ASSERT_JH(jh, !jh->b_committed_data);
2065 0 : J_ASSERT_JH(jh, !jh->b_frozen_data);
2066 0 : return;
2067 0 : case BJ_SyncData:
2068 0 : list = &transaction->t_sync_datalist;
2069 0 : break;
2070 0 : case BJ_Metadata:
2071 0 : transaction->t_nr_buffers++;
2072 0 : list = &transaction->t_buffers;
2073 0 : break;
2074 0 : case BJ_Forget:
2075 0 : list = &transaction->t_forget;
2076 0 : break;
2077 0 : case BJ_IO:
2078 0 : list = &transaction->t_iobuf_list;
2079 0 : break;
2080 0 : case BJ_Shadow:
2081 0 : list = &transaction->t_shadow_list;
2082 0 : break;
2083 0 : case BJ_LogCtl:
2084 0 : list = &transaction->t_log_list;
2085 0 : break;
2086 0 : case BJ_Reserved:
2087 0 : list = &transaction->t_reserved_list;
2088 0 : break;
2089 0 : case BJ_Locked:
2090 0 : list = &transaction->t_locked_list;
2091 0 : break;
2092 0 : }
2093 :
2094 0 : __blist_add_buffer(list, jh);
2095 0 : jh->b_jlist = jlist;
2096 :
2097 0 : if (was_dirty)
2098 0 : set_buffer_jbddirty(bh);
2099 0 : }
2100 :
2101 : void journal_file_buffer(struct journal_head *jh,
2102 : transaction_t *transaction, int jlist)
2103 0 : {
2104 0 : jbd_lock_bh_state(jh2bh(jh));
2105 0 : spin_lock(&transaction->t_journal->j_list_lock);
2106 0 : __journal_file_buffer(jh, transaction, jlist);
2107 0 : spin_unlock(&transaction->t_journal->j_list_lock);
2108 0 : jbd_unlock_bh_state(jh2bh(jh));
2109 0 : }
2110 :
2111 : /*
2112 : * Remove a buffer from its current buffer list in preparation for
2113 : * dropping it from its current transaction entirely. If the buffer has
2114 : * already started to be used by a subsequent transaction, refile the
2115 : * buffer on that transaction's metadata list.
2116 : *
2117 : * Called under journal->j_list_lock
2118 : *
2119 : * Called under jbd_lock_bh_state(jh2bh(jh))
2120 : */
2121 : void __journal_refile_buffer(struct journal_head *jh)
2122 : {
2123 0 : int was_dirty;
2124 0 : struct buffer_head *bh = jh2bh(jh);
2125 0 :
2126 0 : J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2127 0 : if (jh->b_transaction)
2128 0 : assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2129 :
2130 : /* If the buffer is now unused, just drop it. */
2131 0 : if (jh->b_next_transaction == NULL) {
2132 0 : __journal_unfile_buffer(jh);
2133 0 : return;
2134 : }
2135 :
2136 : /*
2137 : * It has been modified by a later transaction: add it to the new
2138 : * transaction's metadata list.
2139 : */
2140 :
2141 0 : was_dirty = test_clear_buffer_jbddirty(bh);
2142 0 : __journal_temp_unlink_buffer(jh);
2143 0 : jh->b_transaction = jh->b_next_transaction;
2144 0 : jh->b_next_transaction = NULL;
2145 0 : __journal_file_buffer(jh, jh->b_transaction,
2146 : jh->b_modified ? BJ_Metadata : BJ_Reserved);
2147 0 : J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2148 :
2149 0 : if (was_dirty)
2150 0 : set_buffer_jbddirty(bh);
2151 0 : }
2152 :
2153 : /*
2154 : * For the unlocked version of this call, also make sure that any
2155 : * hanging journal_head is cleaned up if necessary.
2156 : *
2157 : * __journal_refile_buffer is usually called as part of a single locked
2158 : * operation on a buffer_head, in which the caller is probably going to
2159 : * be hooking the journal_head onto other lists. In that case it is up
2160 : * to the caller to remove the journal_head if necessary. For the
2161 : * unlocked journal_refile_buffer call, the caller isn't going to be
2162 : * doing anything else to the buffer so we need to do the cleanup
2163 : * ourselves to avoid a jh leak.
2164 : *
2165 : * *** The journal_head may be freed by this call! ***
2166 : */
2167 : void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2168 : {
2169 0 : struct buffer_head *bh = jh2bh(jh);
2170 0 :
2171 0 : jbd_lock_bh_state(bh);
2172 0 : spin_lock(&journal->j_list_lock);
2173 :
2174 0 : __journal_refile_buffer(jh);
2175 0 : jbd_unlock_bh_state(bh);
2176 0 : journal_remove_journal_head(bh);
2177 :
2178 0 : spin_unlock(&journal->j_list_lock);
2179 0 : __brelse(bh);
2180 0 : }
|