Branch data 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 : 0 : 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 : 0 : 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 : 0 : static int start_this_handle(journal_t *journal, handle_t *handle)
85 : : {
86 : : transaction_t *transaction;
87 : : int needed;
88 : 0 : int nblocks = handle->h_buffer_credits;
89 : : transaction_t *new_transaction = NULL;
90 : : int ret = 0;
91 : :
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 : : journal->j_max_transaction_buffers);
96 : : ret = -ENOSPC;
97 : : goto out;
98 : : }
99 : :
100 : : alloc_transaction:
101 [ # # ]: 0 : if (!journal->j_running_transaction) {
102 : : new_transaction = kzalloc(sizeof(*new_transaction),
103 : : GFP_NOFS|__GFP_NOFAIL);
104 [ # # ]: 0 : if (!new_transaction) {
105 : : ret = -ENOMEM;
106 : : goto out;
107 : : }
108 : : }
109 : :
110 : : jbd_debug(3, "New handle %p going live.\n", handle);
111 : :
112 : : repeat:
113 : :
114 : : /*
115 : : * We need to hold j_state_lock until t_updates has been incremented,
116 : : * for proper journal barrier handling
117 : : */
118 : : spin_lock(&journal->j_state_lock);
119 : : repeat_locked:
120 [ # # ][ # # ]: 0 : if (is_journal_aborted(journal) ||
121 [ # # ]: 0 : (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) {
122 : : spin_unlock(&journal->j_state_lock);
123 : : ret = -EROFS;
124 : : goto out;
125 : : }
126 : :
127 : : /* Wait on the journal's transaction barrier if necessary */
128 [ # # ]: 0 : if (journal->j_barrier_count) {
129 : : spin_unlock(&journal->j_state_lock);
130 [ # # ][ # # ]: 0 : wait_event(journal->j_wait_transaction_locked,
131 : : journal->j_barrier_count == 0);
132 : : goto repeat;
133 : : }
134 : :
135 [ # # ]: 0 : if (!journal->j_running_transaction) {
136 [ # # ]: 0 : if (!new_transaction) {
137 : : spin_unlock(&journal->j_state_lock);
138 : : goto alloc_transaction;
139 : : }
140 : 0 : get_transaction(journal, new_transaction);
141 : : 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 : : spin_unlock(&journal->j_state_lock);
156 : 0 : schedule();
157 : 0 : finish_wait(&journal->j_wait_transaction_locked, &wait);
158 : : 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 : : 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 : : 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 : : spin_unlock(&journal->j_state_lock);
183 : 0 : schedule();
184 : 0 : finish_wait(&journal->j_wait_transaction_locked, &wait);
185 : : 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 inconsistent 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 : : spin_unlock(&transaction->t_handle_lock);
216 : 0 : __log_wait_for_space(journal);
217 : : 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 : : spin_unlock(&transaction->t_handle_lock);
231 : : spin_unlock(&journal->j_state_lock);
232 : :
233 : : 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 : 0 : static handle_t *new_handle(int nblocks)
244 : : {
245 : : handle_t *handle = jbd_alloc_handle(GFP_NOFS);
246 [ # # ]: 0 : if (!handle)
247 : : return NULL;
248 : 0 : handle->h_buffer_credits = nblocks;
249 : 0 : handle->h_ref = 1;
250 : :
251 : : lockdep_init_map(&handle->h_lockdep_map, "jbd_handle", &jbd_handle_key, 0);
252 : :
253 : 0 : return handle;
254 : : }
255 : :
256 : : /**
257 : : * handle_t *journal_start() - Obtain a new handle.
258 : : * @journal: Journal to start transaction on.
259 : : * @nblocks: number of block buffer we might modify
260 : : *
261 : : * We make sure that the transaction can guarantee at least nblocks of
262 : : * modified buffers in the log. We block until the log can guarantee
263 : : * that much space.
264 : : *
265 : : * This function is visible to journal users (like ext3fs), so is not
266 : : * called with the journal already locked.
267 : : *
268 : : * Return a pointer to a newly allocated handle, or an ERR_PTR() value
269 : : * on failure.
270 : : */
271 : 0 : handle_t *journal_start(journal_t *journal, int nblocks)
272 : : {
273 : 0 : handle_t *handle = journal_current_handle();
274 : : int err;
275 : :
276 [ # # ]: 0 : if (!journal)
277 : : return ERR_PTR(-EROFS);
278 : :
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 : : 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 : : jbd_free_handle(handle);
294 : 0 : current->journal_info = NULL;
295 : : handle = ERR_PTR(err);
296 : : }
297 : 0 : return handle;
298 : : }
299 : :
300 : : /**
301 : : * int journal_extend() - extend buffer credits.
302 : : * @handle: handle to 'extend'
303 : : * @nblocks: nr blocks to try to extend by.
304 : : *
305 : : * Some transactions, such as large extends and truncates, can be done
306 : : * atomically all at once or in several stages. The operation requests
307 : : * a credit for a number of buffer modications in advance, but can
308 : : * extend its credit if it needs more.
309 : : *
310 : : * journal_extend tries to give the running handle more buffer credits.
311 : : * It does not guarantee that allocation - this is a best-effort only.
312 : : * The calling process MUST be able to deal cleanly with a failure to
313 : : * extend here.
314 : : *
315 : : * Return 0 on success, non-zero on failure.
316 : : *
317 : : * return code < 0 implies an error
318 : : * return code > 0 implies normal transaction-full status.
319 : : */
320 : 0 : int journal_extend(handle_t *handle, int nblocks)
321 : : {
322 : 0 : transaction_t *transaction = handle->h_transaction;
323 : 0 : journal_t *journal = transaction->t_journal;
324 : : int result;
325 : : int wanted;
326 : :
327 : : result = -EIO;
328 [ # # ]: 0 : if (is_handle_aborted(handle))
329 : : goto out;
330 : :
331 : : result = 1;
332 : :
333 : : spin_lock(&journal->j_state_lock);
334 : :
335 : : /* Don't extend a locked-down transaction! */
336 [ # # ]: 0 : if (handle->h_transaction->t_state != T_RUNNING) {
337 : : jbd_debug(3, "denied handle %p %d blocks: "
338 : : "transaction not running\n", handle, nblocks);
339 : : goto error_out;
340 : : }
341 : :
342 : : spin_lock(&transaction->t_handle_lock);
343 : 0 : wanted = transaction->t_outstanding_credits + nblocks;
344 : :
345 [ # # ]: 0 : if (wanted > journal->j_max_transaction_buffers) {
346 : : jbd_debug(3, "denied handle %p %d blocks: "
347 : : "transaction too large\n", handle, nblocks);
348 : : goto unlock;
349 : : }
350 : :
351 [ # # ]: 0 : if (wanted > __log_space_left(journal)) {
352 : : jbd_debug(3, "denied handle %p %d blocks: "
353 : : "insufficient log space\n", handle, nblocks);
354 : : goto unlock;
355 : : }
356 : :
357 : 0 : handle->h_buffer_credits += nblocks;
358 : 0 : transaction->t_outstanding_credits += nblocks;
359 : : result = 0;
360 : :
361 : : jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
362 : : unlock:
363 : : spin_unlock(&transaction->t_handle_lock);
364 : : error_out:
365 : : spin_unlock(&journal->j_state_lock);
366 : : out:
367 : 0 : return result;
368 : : }
369 : :
370 : :
371 : : /**
372 : : * int journal_restart() - restart a handle.
373 : : * @handle: handle to restart
374 : : * @nblocks: nr credits requested
375 : : *
376 : : * Restart a handle for a multi-transaction filesystem
377 : : * operation.
378 : : *
379 : : * If the journal_extend() call above fails to grant new buffer credits
380 : : * to a running handle, a call to journal_restart will commit the
381 : : * handle's transaction so far and reattach the handle to a new
382 : : * transaction capabable of guaranteeing the requested number of
383 : : * credits.
384 : : */
385 : :
386 : 0 : int journal_restart(handle_t *handle, int nblocks)
387 : : {
388 : 0 : transaction_t *transaction = handle->h_transaction;
389 : 0 : journal_t *journal = transaction->t_journal;
390 : : int ret;
391 : :
392 : : /* If we've had an abort of any type, don't even think about
393 : : * actually doing the restart! */
394 [ # # ]: 0 : if (is_handle_aborted(handle))
395 : : return 0;
396 : :
397 : : /*
398 : : * First unlink the handle from its current transaction, and start the
399 : : * commit on that.
400 : : */
401 [ # # ]: 0 : J_ASSERT(transaction->t_updates > 0);
402 [ # # ]: 0 : J_ASSERT(journal_current_handle() == handle);
403 : :
404 : : spin_lock(&journal->j_state_lock);
405 : : spin_lock(&transaction->t_handle_lock);
406 : 0 : transaction->t_outstanding_credits -= handle->h_buffer_credits;
407 : 0 : transaction->t_updates--;
408 : :
409 [ # # ]: 0 : if (!transaction->t_updates)
410 : 0 : wake_up(&journal->j_wait_updates);
411 : : spin_unlock(&transaction->t_handle_lock);
412 : :
413 : : jbd_debug(2, "restarting handle %p\n", handle);
414 : 0 : __log_start_commit(journal, transaction->t_tid);
415 : : spin_unlock(&journal->j_state_lock);
416 : :
417 : : lock_map_release(&handle->h_lockdep_map);
418 : 0 : handle->h_buffer_credits = nblocks;
419 : 0 : ret = start_this_handle(journal, handle);
420 : 0 : return ret;
421 : : }
422 : :
423 : :
424 : : /**
425 : : * void journal_lock_updates () - establish a transaction barrier.
426 : : * @journal: Journal to establish a barrier on.
427 : : *
428 : : * This locks out any further updates from being started, and blocks until all
429 : : * existing updates have completed, returning only once the journal is in a
430 : : * quiescent state with no updates running.
431 : : *
432 : : * We do not use simple mutex for synchronization as there are syscalls which
433 : : * want to return with filesystem locked and that trips up lockdep. Also
434 : : * hibernate needs to lock filesystem but locked mutex then blocks hibernation.
435 : : * Since locking filesystem is rare operation, we use simple counter and
436 : : * waitqueue for locking.
437 : : */
438 : 0 : void journal_lock_updates(journal_t *journal)
439 : : {
440 : 0 : DEFINE_WAIT(wait);
441 : :
442 : : wait:
443 : : /* Wait for previous locked operation to finish */
444 [ # # ][ # # ]: 0 : wait_event(journal->j_wait_transaction_locked,
445 : : journal->j_barrier_count == 0);
446 : :
447 : : spin_lock(&journal->j_state_lock);
448 : : /*
449 : : * Check reliably under the lock whether we are the ones winning the race
450 : : * and locking the journal
451 : : */
452 [ # # ]: 0 : if (journal->j_barrier_count > 0) {
453 : : spin_unlock(&journal->j_state_lock);
454 : : goto wait;
455 : : }
456 : 0 : ++journal->j_barrier_count;
457 : :
458 : : /* Wait until there are no running updates */
459 : : while (1) {
460 : 0 : transaction_t *transaction = journal->j_running_transaction;
461 : :
462 [ # # ]: 0 : if (!transaction)
463 : : break;
464 : :
465 : : spin_lock(&transaction->t_handle_lock);
466 [ # # ]: 0 : if (!transaction->t_updates) {
467 : : spin_unlock(&transaction->t_handle_lock);
468 : : break;
469 : : }
470 : 0 : prepare_to_wait(&journal->j_wait_updates, &wait,
471 : : TASK_UNINTERRUPTIBLE);
472 : : spin_unlock(&transaction->t_handle_lock);
473 : : spin_unlock(&journal->j_state_lock);
474 : 0 : schedule();
475 : 0 : finish_wait(&journal->j_wait_updates, &wait);
476 : : spin_lock(&journal->j_state_lock);
477 : : }
478 : : spin_unlock(&journal->j_state_lock);
479 : 0 : }
480 : :
481 : : /**
482 : : * void journal_unlock_updates (journal_t* journal) - release barrier
483 : : * @journal: Journal to release the barrier on.
484 : : *
485 : : * Release a transaction barrier obtained with journal_lock_updates().
486 : : */
487 : 0 : void journal_unlock_updates (journal_t *journal)
488 : : {
489 [ # # ]: 0 : J_ASSERT(journal->j_barrier_count != 0);
490 : :
491 : : spin_lock(&journal->j_state_lock);
492 : 0 : --journal->j_barrier_count;
493 : : spin_unlock(&journal->j_state_lock);
494 : 0 : wake_up(&journal->j_wait_transaction_locked);
495 : 0 : }
496 : :
497 : 0 : static void warn_dirty_buffer(struct buffer_head *bh)
498 : : {
499 : : char b[BDEVNAME_SIZE];
500 : :
501 : 0 : printk(KERN_WARNING
502 : : "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
503 : : "There's a risk of filesystem corruption in case of system "
504 : : "crash.\n",
505 : : bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr);
506 : 0 : }
507 : :
508 : : /*
509 : : * If the buffer is already part of the current transaction, then there
510 : : * is nothing we need to do. If it is already part of a prior
511 : : * transaction which we are still committing to disk, then we need to
512 : : * make sure that we do not overwrite the old copy: we do copy-out to
513 : : * preserve the copy going to disk. We also account the buffer against
514 : : * the handle's metadata buffer credits (unless the buffer is already
515 : : * part of the transaction, that is).
516 : : *
517 : : */
518 : : static int
519 : 0 : do_get_write_access(handle_t *handle, struct journal_head *jh,
520 : : int force_copy)
521 : : {
522 : 0 : struct buffer_head *bh;
523 : : transaction_t *transaction;
524 : : journal_t *journal;
525 : : int error;
526 : : char *frozen_buffer = NULL;
527 : : int need_copy = 0;
528 : :
529 [ # # ]: 0 : if (is_handle_aborted(handle))
530 : : return -EROFS;
531 : :
532 : 0 : transaction = handle->h_transaction;
533 : 0 : journal = transaction->t_journal;
534 : :
535 : : jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy);
536 : :
537 : : JBUFFER_TRACE(jh, "entry");
538 : : repeat:
539 : : bh = jh2bh(jh);
540 : :
541 : : /* @@@ Need to check for errors here at some point. */
542 : :
543 : : lock_buffer(bh);
544 : : jbd_lock_bh_state(bh);
545 : :
546 : : /* We now hold the buffer lock so it is safe to query the buffer
547 : : * state. Is the buffer dirty?
548 : : *
549 : : * If so, there are two possibilities. The buffer may be
550 : : * non-journaled, and undergoing a quite legitimate writeback.
551 : : * Otherwise, it is journaled, and we don't expect dirty buffers
552 : : * in that state (the buffers should be marked JBD_Dirty
553 : : * instead.) So either the IO is being done under our own
554 : : * control and this is a bug, or it's a third party IO such as
555 : : * dump(8) (which may leave the buffer scheduled for read ---
556 : : * ie. locked but not dirty) or tune2fs (which may actually have
557 : : * the buffer dirtied, ugh.) */
558 : :
559 [ # # ]: 0 : if (buffer_dirty(bh)) {
560 : : /*
561 : : * First question: is this buffer already part of the current
562 : : * transaction or the existing committing transaction?
563 : : */
564 [ # # ]: 0 : if (jh->b_transaction) {
565 [ # # ][ # # ]: 0 : J_ASSERT_JH(jh,
566 : : jh->b_transaction == transaction ||
567 : : jh->b_transaction ==
568 : : journal->j_committing_transaction);
569 [ # # ]: 0 : if (jh->b_next_transaction)
570 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_next_transaction ==
571 : : transaction);
572 : 0 : warn_dirty_buffer(bh);
573 : : }
574 : : /*
575 : : * In any case we need to clean the dirty flag and we must
576 : : * do it under the buffer lock to be sure we don't race
577 : : * with running write-out.
578 : : */
579 : : JBUFFER_TRACE(jh, "Journalling dirty buffer");
580 : : clear_buffer_dirty(bh);
581 : : set_buffer_jbddirty(bh);
582 : : }
583 : :
584 : 0 : unlock_buffer(bh);
585 : :
586 : : error = -EROFS;
587 [ # # ]: 0 : if (is_handle_aborted(handle)) {
588 : : jbd_unlock_bh_state(bh);
589 : : goto out;
590 : : }
591 : : error = 0;
592 : :
593 : : /*
594 : : * The buffer is already part of this transaction if b_transaction or
595 : : * b_next_transaction points to it
596 : : */
597 [ # # ][ # # ]: 0 : if (jh->b_transaction == transaction ||
598 : 0 : jh->b_next_transaction == transaction)
599 : : goto done;
600 : :
601 : : /*
602 : : * this is the first time this transaction is touching this buffer,
603 : : * reset the modified flag
604 : : */
605 : 0 : jh->b_modified = 0;
606 : :
607 : : /*
608 : : * If there is already a copy-out version of this buffer, then we don't
609 : : * need to make another one
610 : : */
611 [ # # ]: 0 : if (jh->b_frozen_data) {
612 : : JBUFFER_TRACE(jh, "has frozen data");
613 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
614 : 0 : jh->b_next_transaction = transaction;
615 : 0 : goto done;
616 : : }
617 : :
618 : : /* Is there data here we need to preserve? */
619 : :
620 [ # # ][ # # ]: 0 : if (jh->b_transaction && jh->b_transaction != transaction) {
621 : : JBUFFER_TRACE(jh, "owned by older transaction");
622 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
623 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_transaction ==
624 : : journal->j_committing_transaction);
625 : :
626 : : /* There is one case we have to be very careful about.
627 : : * If the committing transaction is currently writing
628 : : * this buffer out to disk and has NOT made a copy-out,
629 : : * then we cannot modify the buffer contents at all
630 : : * right now. The essence of copy-out is that it is the
631 : : * extra copy, not the primary copy, which gets
632 : : * journaled. If the primary copy is already going to
633 : : * disk then we cannot do copy-out here. */
634 : :
635 [ # # ]: 0 : if (jh->b_jlist == BJ_Shadow) {
636 : 0 : DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
637 : : wait_queue_head_t *wqh;
638 : :
639 : 0 : wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
640 : :
641 : : JBUFFER_TRACE(jh, "on shadow: sleep");
642 : : jbd_unlock_bh_state(bh);
643 : : /* commit wakes up all shadow buffers after IO */
644 : : for ( ; ; ) {
645 : 0 : prepare_to_wait(wqh, &wait.wait,
646 : : TASK_UNINTERRUPTIBLE);
647 [ # # ]: 0 : if (jh->b_jlist != BJ_Shadow)
648 : : break;
649 : 0 : schedule();
650 : 0 : }
651 : 0 : finish_wait(wqh, &wait.wait);
652 : : goto repeat;
653 : : }
654 : :
655 : : /* Only do the copy if the currently-owning transaction
656 : : * still needs it. If it is on the Forget list, the
657 : : * committing transaction is past that stage. The
658 : : * buffer had better remain locked during the kmalloc,
659 : : * but that should be true --- we hold the journal lock
660 : : * still and the buffer is already on the BUF_JOURNAL
661 : : * list so won't be flushed.
662 : : *
663 : : * Subtle point, though: if this is a get_undo_access,
664 : : * then we will be relying on the frozen_data to contain
665 : : * the new value of the committed_data record after the
666 : : * transaction, so we HAVE to force the frozen_data copy
667 : : * in that case. */
668 : :
669 [ # # ][ # # ]: 0 : if (jh->b_jlist != BJ_Forget || force_copy) {
670 : : JBUFFER_TRACE(jh, "generate frozen data");
671 [ # # ]: 0 : if (!frozen_buffer) {
672 : : JBUFFER_TRACE(jh, "allocate memory for buffer");
673 : : jbd_unlock_bh_state(bh);
674 : : frozen_buffer =
675 : 0 : jbd_alloc(jh2bh(jh)->b_size,
676 : : GFP_NOFS);
677 [ # # ]: 0 : if (!frozen_buffer) {
678 : 0 : printk(KERN_EMERG
679 : : "%s: OOM for frozen_buffer\n",
680 : : __func__);
681 : : JBUFFER_TRACE(jh, "oom!");
682 : : error = -ENOMEM;
683 : : jbd_lock_bh_state(bh);
684 : : goto done;
685 : : }
686 : : goto repeat;
687 : : }
688 : 0 : jh->b_frozen_data = frozen_buffer;
689 : : frozen_buffer = NULL;
690 : : need_copy = 1;
691 : : }
692 : 0 : jh->b_next_transaction = transaction;
693 : : }
694 : :
695 : :
696 : : /*
697 : : * Finally, if the buffer is not journaled right now, we need to make
698 : : * sure it doesn't get written to disk before the caller actually
699 : : * commits the new data
700 : : */
701 [ # # ]: 0 : if (!jh->b_transaction) {
702 : : JBUFFER_TRACE(jh, "no transaction");
703 [ # # ]: 0 : J_ASSERT_JH(jh, !jh->b_next_transaction);
704 : : JBUFFER_TRACE(jh, "file as BJ_Reserved");
705 : : spin_lock(&journal->j_list_lock);
706 : 0 : __journal_file_buffer(jh, transaction, BJ_Reserved);
707 : : spin_unlock(&journal->j_list_lock);
708 : : }
709 : :
710 : : done:
711 [ # # ]: 0 : if (need_copy) {
712 : : struct page *page;
713 : : int offset;
714 : : char *source;
715 : :
716 [ # # ]: 0 : J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
717 : : "Possible IO failure.\n");
718 : 0 : page = jh2bh(jh)->b_page;
719 : 0 : offset = offset_in_page(jh2bh(jh)->b_data);
720 : 0 : source = kmap_atomic(page);
721 : 0 : memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
722 : 0 : kunmap_atomic(source);
723 : : }
724 : : jbd_unlock_bh_state(bh);
725 : :
726 : : /*
727 : : * If we are about to journal a buffer, then any revoke pending on it is
728 : : * no longer valid
729 : : */
730 : 0 : journal_cancel_revoke(handle, jh);
731 : :
732 : : out:
733 [ # # ]: 0 : if (unlikely(frozen_buffer)) /* It's usually NULL */
734 : 0 : jbd_free(frozen_buffer, bh->b_size);
735 : :
736 : : JBUFFER_TRACE(jh, "exit");
737 : 0 : return error;
738 : : }
739 : :
740 : : /**
741 : : * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
742 : : * @handle: transaction to add buffer modifications to
743 : : * @bh: bh to be used for metadata writes
744 : : *
745 : : * Returns an error code or 0 on success.
746 : : *
747 : : * In full data journalling mode the buffer may be of type BJ_AsyncData,
748 : : * because we're write()ing a buffer which is also part of a shared mapping.
749 : : */
750 : :
751 : 0 : int journal_get_write_access(handle_t *handle, struct buffer_head *bh)
752 : : {
753 : 0 : struct journal_head *jh = journal_add_journal_head(bh);
754 : : int rc;
755 : :
756 : : /* We do not want to get caught playing with fields which the
757 : : * log thread also manipulates. Make sure that the buffer
758 : : * completes any outstanding IO before proceeding. */
759 : 0 : rc = do_get_write_access(handle, jh, 0);
760 : 0 : journal_put_journal_head(jh);
761 : 0 : return rc;
762 : : }
763 : :
764 : :
765 : : /*
766 : : * When the user wants to journal a newly created buffer_head
767 : : * (ie. getblk() returned a new buffer and we are going to populate it
768 : : * manually rather than reading off disk), then we need to keep the
769 : : * buffer_head locked until it has been completely filled with new
770 : : * data. In this case, we should be able to make the assertion that
771 : : * the bh is not already part of an existing transaction.
772 : : *
773 : : * The buffer should already be locked by the caller by this point.
774 : : * There is no lock ranking violation: it was a newly created,
775 : : * unlocked buffer beforehand. */
776 : :
777 : : /**
778 : : * int journal_get_create_access () - notify intent to use newly created bh
779 : : * @handle: transaction to new buffer to
780 : : * @bh: new buffer.
781 : : *
782 : : * Call this if you create a new bh.
783 : : */
784 : 0 : int journal_get_create_access(handle_t *handle, struct buffer_head *bh)
785 : : {
786 : 0 : transaction_t *transaction = handle->h_transaction;
787 : 0 : journal_t *journal = transaction->t_journal;
788 : 0 : struct journal_head *jh = journal_add_journal_head(bh);
789 : : int err;
790 : :
791 : : jbd_debug(5, "journal_head %p\n", jh);
792 : : err = -EROFS;
793 [ # # ]: 0 : if (is_handle_aborted(handle))
794 : : goto out;
795 : : err = 0;
796 : :
797 : : JBUFFER_TRACE(jh, "entry");
798 : : /*
799 : : * The buffer may already belong to this transaction due to pre-zeroing
800 : : * in the filesystem's new_block code. It may also be on the previous,
801 : : * committing transaction's lists, but it HAS to be in Forget state in
802 : : * that case: the transaction must have deleted the buffer for it to be
803 : : * reused here.
804 : : */
805 : : jbd_lock_bh_state(bh);
806 : : spin_lock(&journal->j_list_lock);
807 [ # # ][ # # ]: 0 : J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
[ # # ][ # # ]
[ # # ][ # # ]
808 : : jh->b_transaction == NULL ||
809 : : (jh->b_transaction == journal->j_committing_transaction &&
810 : : jh->b_jlist == BJ_Forget)));
811 : :
812 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
813 [ # # ]: 0 : J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
814 : :
815 [ # # ]: 0 : if (jh->b_transaction == NULL) {
816 : : /*
817 : : * Previous journal_forget() could have left the buffer
818 : : * with jbddirty bit set because it was being committed. When
819 : : * the commit finished, we've filed the buffer for
820 : : * checkpointing and marked it dirty. Now we are reallocating
821 : : * the buffer so the transaction freeing it must have
822 : : * committed and so it's safe to clear the dirty bit.
823 : : */
824 : : clear_buffer_dirty(jh2bh(jh));
825 : :
826 : : /* first access by this transaction */
827 : 0 : jh->b_modified = 0;
828 : :
829 : : JBUFFER_TRACE(jh, "file as BJ_Reserved");
830 : 0 : __journal_file_buffer(jh, transaction, BJ_Reserved);
831 [ # # ]: 0 : } else if (jh->b_transaction == journal->j_committing_transaction) {
832 : : /* first access by this transaction */
833 : 0 : jh->b_modified = 0;
834 : :
835 : : JBUFFER_TRACE(jh, "set next transaction");
836 : 0 : jh->b_next_transaction = transaction;
837 : : }
838 : : spin_unlock(&journal->j_list_lock);
839 : : jbd_unlock_bh_state(bh);
840 : :
841 : : /*
842 : : * akpm: I added this. ext3_alloc_branch can pick up new indirect
843 : : * blocks which contain freed but then revoked metadata. We need
844 : : * to cancel the revoke in case we end up freeing it yet again
845 : : * and the reallocating as data - this would cause a second revoke,
846 : : * which hits an assertion error.
847 : : */
848 : : JBUFFER_TRACE(jh, "cancelling revoke");
849 : 0 : journal_cancel_revoke(handle, jh);
850 : : out:
851 : 0 : journal_put_journal_head(jh);
852 : 0 : return err;
853 : : }
854 : :
855 : : /**
856 : : * int journal_get_undo_access() - Notify intent to modify metadata with non-rewindable consequences
857 : : * @handle: transaction
858 : : * @bh: buffer to undo
859 : : *
860 : : * Sometimes there is a need to distinguish between metadata which has
861 : : * been committed to disk and that which has not. The ext3fs code uses
862 : : * this for freeing and allocating space, we have to make sure that we
863 : : * do not reuse freed space until the deallocation has been committed,
864 : : * since if we overwrote that space we would make the delete
865 : : * un-rewindable in case of a crash.
866 : : *
867 : : * To deal with that, journal_get_undo_access requests write access to a
868 : : * buffer for parts of non-rewindable operations such as delete
869 : : * operations on the bitmaps. The journaling code must keep a copy of
870 : : * the buffer's contents prior to the undo_access call until such time
871 : : * as we know that the buffer has definitely been committed to disk.
872 : : *
873 : : * We never need to know which transaction the committed data is part
874 : : * of, buffers touched here are guaranteed to be dirtied later and so
875 : : * will be committed to a new transaction in due course, at which point
876 : : * we can discard the old committed data pointer.
877 : : *
878 : : * Returns error number or 0 on success.
879 : : */
880 : 0 : int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
881 : : {
882 : : int err;
883 : 0 : struct journal_head *jh = journal_add_journal_head(bh);
884 : : char *committed_data = NULL;
885 : :
886 : : JBUFFER_TRACE(jh, "entry");
887 : :
888 : : /*
889 : : * Do this first --- it can drop the journal lock, so we want to
890 : : * make sure that obtaining the committed_data is done
891 : : * atomically wrt. completion of any outstanding commits.
892 : : */
893 : 0 : err = do_get_write_access(handle, jh, 1);
894 [ # # ]: 0 : if (err)
895 : : goto out;
896 : :
897 : : repeat:
898 [ # # ]: 0 : if (!jh->b_committed_data) {
899 : 0 : committed_data = jbd_alloc(jh2bh(jh)->b_size, GFP_NOFS);
900 [ # # ]: 0 : if (!committed_data) {
901 : 0 : printk(KERN_EMERG "%s: No memory for committed data\n",
902 : : __func__);
903 : : err = -ENOMEM;
904 : 0 : goto out;
905 : : }
906 : : }
907 : :
908 : : jbd_lock_bh_state(bh);
909 [ # # ]: 0 : if (!jh->b_committed_data) {
910 : : /* Copy out the current buffer contents into the
911 : : * preserved, committed copy. */
912 : : JBUFFER_TRACE(jh, "generate b_committed data");
913 [ # # ]: 0 : if (!committed_data) {
914 : : jbd_unlock_bh_state(bh);
915 : : goto repeat;
916 : : }
917 : :
918 : 0 : jh->b_committed_data = committed_data;
919 : : committed_data = NULL;
920 : 0 : memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
921 : : }
922 : : jbd_unlock_bh_state(bh);
923 : : out:
924 : 0 : journal_put_journal_head(jh);
925 [ # # ]: 0 : if (unlikely(committed_data))
926 : 0 : jbd_free(committed_data, bh->b_size);
927 : 0 : return err;
928 : : }
929 : :
930 : : /**
931 : : * int journal_dirty_data() - mark a buffer as containing dirty data to be flushed
932 : : * @handle: transaction
933 : : * @bh: bufferhead to mark
934 : : *
935 : : * Description:
936 : : * Mark a buffer as containing dirty data which needs to be flushed before
937 : : * we can commit the current transaction.
938 : : *
939 : : * The buffer is placed on the transaction's data list and is marked as
940 : : * belonging to the transaction.
941 : : *
942 : : * Returns error number or 0 on success.
943 : : *
944 : : * journal_dirty_data() can be called via page_launder->ext3_writepage
945 : : * by kswapd.
946 : : */
947 : 0 : int journal_dirty_data(handle_t *handle, struct buffer_head *bh)
948 : : {
949 : 0 : journal_t *journal = handle->h_transaction->t_journal;
950 : : int need_brelse = 0;
951 : : struct journal_head *jh;
952 : : int ret = 0;
953 : :
954 [ # # ]: 0 : if (is_handle_aborted(handle))
955 : : return ret;
956 : :
957 : 0 : jh = journal_add_journal_head(bh);
958 : : JBUFFER_TRACE(jh, "entry");
959 : :
960 : : /*
961 : : * The buffer could *already* be dirty. Writeout can start
962 : : * at any time.
963 : : */
964 : : jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
965 : :
966 : : /*
967 : : * What if the buffer is already part of a running transaction?
968 : : *
969 : : * There are two cases:
970 : : * 1) It is part of the current running transaction. Refile it,
971 : : * just in case we have allocated it as metadata, deallocated
972 : : * it, then reallocated it as data.
973 : : * 2) It is part of the previous, still-committing transaction.
974 : : * If all we want to do is to guarantee that the buffer will be
975 : : * written to disk before this new transaction commits, then
976 : : * being sure that the *previous* transaction has this same
977 : : * property is sufficient for us! Just leave it on its old
978 : : * transaction.
979 : : *
980 : : * In case (2), the buffer must not already exist as metadata
981 : : * --- that would violate write ordering (a transaction is free
982 : : * to write its data at any point, even before the previous
983 : : * committing transaction has committed). The caller must
984 : : * never, ever allow this to happen: there's nothing we can do
985 : : * about it in this layer.
986 : : */
987 : : jbd_lock_bh_state(bh);
988 : : spin_lock(&journal->j_list_lock);
989 : :
990 : : /* Now that we have bh_state locked, are we really still mapped? */
991 [ # # ]: 0 : if (!buffer_mapped(bh)) {
992 : : JBUFFER_TRACE(jh, "unmapped buffer, bailing out");
993 : : goto no_journal;
994 : : }
995 : :
996 [ # # ]: 0 : if (jh->b_transaction) {
997 : : JBUFFER_TRACE(jh, "has transaction");
998 [ # # ]: 0 : if (jh->b_transaction != handle->h_transaction) {
999 : : JBUFFER_TRACE(jh, "belongs to older transaction");
1000 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_transaction ==
1001 : : journal->j_committing_transaction);
1002 : :
1003 : : /* @@@ IS THIS TRUE ? */
1004 : : /*
1005 : : * Not any more. Scenario: someone does a write()
1006 : : * in data=journal mode. The buffer's transaction has
1007 : : * moved into commit. Then someone does another
1008 : : * write() to the file. We do the frozen data copyout
1009 : : * and set b_next_transaction to point to j_running_t.
1010 : : * And while we're in that state, someone does a
1011 : : * writepage() in an attempt to pageout the same area
1012 : : * of the file via a shared mapping. At present that
1013 : : * calls journal_dirty_data(), and we get right here.
1014 : : * It may be too late to journal the data. Simply
1015 : : * falling through to the next test will suffice: the
1016 : : * data will be dirty and wil be checkpointed. The
1017 : : * ordering comments in the next comment block still
1018 : : * apply.
1019 : : */
1020 : : //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1021 : :
1022 : : /*
1023 : : * If we're journalling data, and this buffer was
1024 : : * subject to a write(), it could be metadata, forget
1025 : : * or shadow against the committing transaction. Now,
1026 : : * someone has dirtied the same darn page via a mapping
1027 : : * and it is being writepage()'d.
1028 : : * We *could* just steal the page from commit, with some
1029 : : * fancy locking there. Instead, we just skip it -
1030 : : * don't tie the page's buffers to the new transaction
1031 : : * at all.
1032 : : * Implication: if we crash before the writepage() data
1033 : : * is written into the filesystem, recovery will replay
1034 : : * the write() data.
1035 : : */
1036 [ # # ]: 0 : if (jh->b_jlist != BJ_None &&
1037 : 0 : jh->b_jlist != BJ_SyncData &&
1038 : : jh->b_jlist != BJ_Locked) {
1039 : : JBUFFER_TRACE(jh, "Not stealing");
1040 : : goto no_journal;
1041 : : }
1042 : :
1043 : : /*
1044 : : * This buffer may be undergoing writeout in commit. We
1045 : : * can't return from here and let the caller dirty it
1046 : : * again because that can cause the write-out loop in
1047 : : * commit to never terminate.
1048 : : */
1049 [ # # ]: 0 : if (buffer_dirty(bh)) {
1050 : : get_bh(bh);
1051 : : spin_unlock(&journal->j_list_lock);
1052 : : jbd_unlock_bh_state(bh);
1053 : : need_brelse = 1;
1054 : 0 : sync_dirty_buffer(bh);
1055 : : jbd_lock_bh_state(bh);
1056 : : spin_lock(&journal->j_list_lock);
1057 : : /* Since we dropped the lock... */
1058 [ # # ]: 0 : if (!buffer_mapped(bh)) {
1059 : : JBUFFER_TRACE(jh, "buffer got unmapped");
1060 : : goto no_journal;
1061 : : }
1062 : : /* The buffer may become locked again at any
1063 : : time if it is redirtied */
1064 : : }
1065 : :
1066 : : /*
1067 : : * We cannot remove the buffer with io error from the
1068 : : * committing transaction, because otherwise it would
1069 : : * miss the error and the commit would not abort.
1070 : : */
1071 [ # # ]: 0 : if (unlikely(!buffer_uptodate(bh))) {
1072 : : ret = -EIO;
1073 : : goto no_journal;
1074 : : }
1075 : : /* We might have slept so buffer could be refiled now */
1076 [ # # ][ # # ]: 0 : if (jh->b_transaction != NULL &&
1077 : 0 : jh->b_transaction != handle->h_transaction) {
1078 : : JBUFFER_TRACE(jh, "unfile from commit");
1079 : 0 : __journal_temp_unlink_buffer(jh);
1080 : : /* It still points to the committing
1081 : : * transaction; move it to this one so
1082 : : * that the refile assert checks are
1083 : : * happy. */
1084 : 0 : jh->b_transaction = handle->h_transaction;
1085 : : }
1086 : : /* The buffer will be refiled below */
1087 : :
1088 : : }
1089 : : /*
1090 : : * Special case --- the buffer might actually have been
1091 : : * allocated and then immediately deallocated in the previous,
1092 : : * committing transaction, so might still be left on that
1093 : : * transaction's metadata lists.
1094 : : */
1095 [ # # ]: 0 : if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
1096 : : JBUFFER_TRACE(jh, "not on correct data list: unfile");
1097 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1098 : : JBUFFER_TRACE(jh, "file as data");
1099 : 0 : __journal_file_buffer(jh, handle->h_transaction,
1100 : : BJ_SyncData);
1101 : : }
1102 : : } else {
1103 : : JBUFFER_TRACE(jh, "not on a transaction");
1104 : 0 : __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1105 : : }
1106 : : no_journal:
1107 : : spin_unlock(&journal->j_list_lock);
1108 : : jbd_unlock_bh_state(bh);
1109 [ # # ]: 0 : if (need_brelse) {
1110 : : BUFFER_TRACE(bh, "brelse");
1111 : 0 : __brelse(bh);
1112 : : }
1113 : : JBUFFER_TRACE(jh, "exit");
1114 : 0 : journal_put_journal_head(jh);
1115 : 0 : return ret;
1116 : : }
1117 : :
1118 : : /**
1119 : : * int journal_dirty_metadata() - mark a buffer as containing dirty metadata
1120 : : * @handle: transaction to add buffer to.
1121 : : * @bh: buffer to mark
1122 : : *
1123 : : * Mark dirty metadata which needs to be journaled as part of the current
1124 : : * transaction.
1125 : : *
1126 : : * The buffer is placed on the transaction's metadata list and is marked
1127 : : * as belonging to the transaction.
1128 : : *
1129 : : * Returns error number or 0 on success.
1130 : : *
1131 : : * Special care needs to be taken if the buffer already belongs to the
1132 : : * current committing transaction (in which case we should have frozen
1133 : : * data present for that commit). In that case, we don't relink the
1134 : : * buffer: that only gets done when the old transaction finally
1135 : : * completes its commit.
1136 : : */
1137 : 0 : int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1138 : : {
1139 : 0 : transaction_t *transaction = handle->h_transaction;
1140 : 0 : journal_t *journal = transaction->t_journal;
1141 : : struct journal_head *jh = bh2jh(bh);
1142 : :
1143 : : jbd_debug(5, "journal_head %p\n", jh);
1144 : : JBUFFER_TRACE(jh, "entry");
1145 [ # # ]: 0 : if (is_handle_aborted(handle))
1146 : : goto out;
1147 : :
1148 : : jbd_lock_bh_state(bh);
1149 : :
1150 [ # # ]: 0 : if (jh->b_modified == 0) {
1151 : : /*
1152 : : * This buffer's got modified and becoming part
1153 : : * of the transaction. This needs to be done
1154 : : * once a transaction -bzzz
1155 : : */
1156 : 0 : jh->b_modified = 1;
1157 [ # # ]: 0 : J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1158 : 0 : handle->h_buffer_credits--;
1159 : : }
1160 : :
1161 : : /*
1162 : : * fastpath, to avoid expensive locking. If this buffer is already
1163 : : * on the running transaction's metadata list there is nothing to do.
1164 : : * Nobody can take it off again because there is a handle open.
1165 : : * I _think_ we're OK here with SMP barriers - a mistaken decision will
1166 : : * result in this test being false, so we go in and take the locks.
1167 : : */
1168 [ # # ][ # # ]: 0 : if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1169 : : JBUFFER_TRACE(jh, "fastpath");
1170 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_transaction ==
1171 : : journal->j_running_transaction);
1172 : : goto out_unlock_bh;
1173 : : }
1174 : :
1175 : : set_buffer_jbddirty(bh);
1176 : :
1177 : : /*
1178 : : * Metadata already on the current transaction list doesn't
1179 : : * need to be filed. Metadata on another transaction's list must
1180 : : * be committing, and will be refiled once the commit completes:
1181 : : * leave it alone for now.
1182 : : */
1183 [ # # ]: 0 : if (jh->b_transaction != transaction) {
1184 : : JBUFFER_TRACE(jh, "already on other transaction");
1185 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_transaction ==
1186 : : journal->j_committing_transaction);
1187 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1188 : : /* And this case is illegal: we can't reuse another
1189 : : * transaction's data buffer, ever. */
1190 : : goto out_unlock_bh;
1191 : : }
1192 : :
1193 : : /* That test should have eliminated the following case: */
1194 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
1195 : :
1196 : : JBUFFER_TRACE(jh, "file as BJ_Metadata");
1197 : : spin_lock(&journal->j_list_lock);
1198 : 0 : __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1199 : : spin_unlock(&journal->j_list_lock);
1200 : : out_unlock_bh:
1201 : : jbd_unlock_bh_state(bh);
1202 : : out:
1203 : : JBUFFER_TRACE(jh, "exit");
1204 : 0 : return 0;
1205 : : }
1206 : :
1207 : : /*
1208 : : * journal_release_buffer: undo a get_write_access without any buffer
1209 : : * updates, if the update decided in the end that it didn't need access.
1210 : : *
1211 : : */
1212 : : void
1213 : 0 : journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1214 : : {
1215 : : BUFFER_TRACE(bh, "entry");
1216 : 0 : }
1217 : :
1218 : : /**
1219 : : * void journal_forget() - bforget() for potentially-journaled buffers.
1220 : : * @handle: transaction handle
1221 : : * @bh: bh to 'forget'
1222 : : *
1223 : : * We can only do the bforget if there are no commits pending against the
1224 : : * buffer. If the buffer is dirty in the current running transaction we
1225 : : * can safely unlink it.
1226 : : *
1227 : : * bh may not be a journalled buffer at all - it may be a non-JBD
1228 : : * buffer which came off the hashtable. Check for this.
1229 : : *
1230 : : * Decrements bh->b_count by one.
1231 : : *
1232 : : * Allow this call even if the handle has aborted --- it may be part of
1233 : : * the caller's cleanup after an abort.
1234 : : */
1235 : 0 : int journal_forget (handle_t *handle, struct buffer_head *bh)
1236 : : {
1237 : 0 : transaction_t *transaction = handle->h_transaction;
1238 : 0 : journal_t *journal = transaction->t_journal;
1239 : : struct journal_head *jh;
1240 : : int drop_reserve = 0;
1241 : : int err = 0;
1242 : : int was_modified = 0;
1243 : :
1244 : : BUFFER_TRACE(bh, "entry");
1245 : :
1246 : : jbd_lock_bh_state(bh);
1247 : : spin_lock(&journal->j_list_lock);
1248 : :
1249 [ # # ]: 0 : if (!buffer_jbd(bh))
1250 : : goto not_jbd;
1251 : : jh = bh2jh(bh);
1252 : :
1253 : : /* Critical error: attempting to delete a bitmap buffer, maybe?
1254 : : * Don't do any jbd operations, and return an error. */
1255 [ # # ][ # # ]: 0 : if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1256 : : "inconsistent data on disk")) {
1257 : : err = -EIO;
1258 : : goto not_jbd;
1259 : : }
1260 : :
1261 : : /* keep track of whether or not this transaction modified us */
1262 : 0 : was_modified = jh->b_modified;
1263 : :
1264 : : /*
1265 : : * The buffer's going from the transaction, we must drop
1266 : : * all references -bzzz
1267 : : */
1268 : 0 : jh->b_modified = 0;
1269 : :
1270 [ # # ]: 0 : if (jh->b_transaction == handle->h_transaction) {
1271 [ # # ]: 0 : J_ASSERT_JH(jh, !jh->b_frozen_data);
1272 : :
1273 : : /* If we are forgetting a buffer which is already part
1274 : : * of this transaction, then we can just drop it from
1275 : : * the transaction immediately. */
1276 : : clear_buffer_dirty(bh);
1277 : : clear_buffer_jbddirty(bh);
1278 : :
1279 : : JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1280 : :
1281 : : /*
1282 : : * we only want to drop a reference if this transaction
1283 : : * modified the buffer
1284 : : */
1285 [ # # ]: 0 : if (was_modified)
1286 : : drop_reserve = 1;
1287 : :
1288 : : /*
1289 : : * We are no longer going to journal this buffer.
1290 : : * However, the commit of this transaction is still
1291 : : * important to the buffer: the delete that we are now
1292 : : * processing might obsolete an old log entry, so by
1293 : : * committing, we can satisfy the buffer's checkpoint.
1294 : : *
1295 : : * So, if we have a checkpoint on the buffer, we should
1296 : : * now refile the buffer on our BJ_Forget list so that
1297 : : * we know to remove the checkpoint after we commit.
1298 : : */
1299 : :
1300 [ # # ]: 0 : if (jh->b_cp_transaction) {
1301 : 0 : __journal_temp_unlink_buffer(jh);
1302 : 0 : __journal_file_buffer(jh, transaction, BJ_Forget);
1303 : : } else {
1304 : : __journal_unfile_buffer(jh);
1305 [ # # ]: 0 : if (!buffer_jbd(bh)) {
1306 : : spin_unlock(&journal->j_list_lock);
1307 : : jbd_unlock_bh_state(bh);
1308 : 0 : __bforget(bh);
1309 : 0 : goto drop;
1310 : : }
1311 : : }
1312 [ # # ]: 0 : } else if (jh->b_transaction) {
1313 [ # # ]: 0 : J_ASSERT_JH(jh, (jh->b_transaction ==
1314 : : journal->j_committing_transaction));
1315 : : /* However, if the buffer is still owned by a prior
1316 : : * (committing) transaction, we can't drop it yet... */
1317 : : JBUFFER_TRACE(jh, "belongs to older transaction");
1318 : : /* ... but we CAN drop it from the new transaction if we
1319 : : * have also modified it since the original commit. */
1320 : :
1321 [ # # ]: 0 : if (jh->b_next_transaction) {
1322 [ # # ]: 0 : J_ASSERT(jh->b_next_transaction == transaction);
1323 : 0 : jh->b_next_transaction = NULL;
1324 : :
1325 : : /*
1326 : : * only drop a reference if this transaction modified
1327 : : * the buffer
1328 : : */
1329 [ # # ]: 0 : if (was_modified)
1330 : : drop_reserve = 1;
1331 : : }
1332 : : }
1333 : :
1334 : : not_jbd:
1335 : : spin_unlock(&journal->j_list_lock);
1336 : : jbd_unlock_bh_state(bh);
1337 : 0 : __brelse(bh);
1338 : : drop:
1339 [ # # ]: 0 : if (drop_reserve) {
1340 : : /* no need to reserve log space for this block -bzzz */
1341 : 0 : handle->h_buffer_credits++;
1342 : : }
1343 : 0 : return err;
1344 : : }
1345 : :
1346 : : /**
1347 : : * int journal_stop() - complete a transaction
1348 : : * @handle: tranaction to complete.
1349 : : *
1350 : : * All done for a particular handle.
1351 : : *
1352 : : * There is not much action needed here. We just return any remaining
1353 : : * buffer credits to the transaction and remove the handle. The only
1354 : : * complication is that we need to start a commit operation if the
1355 : : * filesystem is marked for synchronous update.
1356 : : *
1357 : : * journal_stop itself will not usually return an error, but it may
1358 : : * do so in unusual circumstances. In particular, expect it to
1359 : : * return -EIO if a journal_abort has been executed since the
1360 : : * transaction began.
1361 : : */
1362 : 0 : int journal_stop(handle_t *handle)
1363 : : {
1364 : 0 : transaction_t *transaction = handle->h_transaction;
1365 : 0 : journal_t *journal = transaction->t_journal;
1366 : : int err;
1367 : : pid_t pid;
1368 : :
1369 [ # # ]: 0 : J_ASSERT(journal_current_handle() == handle);
1370 : :
1371 [ # # ]: 0 : if (is_handle_aborted(handle))
1372 : : err = -EIO;
1373 : : else {
1374 [ # # ]: 0 : J_ASSERT(transaction->t_updates > 0);
1375 : : err = 0;
1376 : : }
1377 : :
1378 [ # # ]: 0 : if (--handle->h_ref > 0) {
1379 : : jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1380 : : handle->h_ref);
1381 : : return err;
1382 : : }
1383 : :
1384 : : jbd_debug(4, "Handle %p going down\n", handle);
1385 : :
1386 : : /*
1387 : : * Implement synchronous transaction batching. If the handle
1388 : : * was synchronous, don't force a commit immediately. Let's
1389 : : * yield and let another thread piggyback onto this transaction.
1390 : : * Keep doing that while new threads continue to arrive.
1391 : : * It doesn't cost much - we're about to run a commit and sleep
1392 : : * on IO anyway. Speeds up many-threaded, many-dir operations
1393 : : * by 30x or more...
1394 : : *
1395 : : * We try and optimize the sleep time against what the underlying disk
1396 : : * can do, instead of having a static sleep time. This is useful for
1397 : : * the case where our storage is so fast that it is more optimal to go
1398 : : * ahead and force a flush and wait for the transaction to be committed
1399 : : * than it is to wait for an arbitrary amount of time for new writers to
1400 : : * join the transaction. We achieve this by measuring how long it takes
1401 : : * to commit a transaction, and compare it with how long this
1402 : : * transaction has been running, and if run time < commit time then we
1403 : : * sleep for the delta and commit. This greatly helps super fast disks
1404 : : * that would see slowdowns as more threads started doing fsyncs.
1405 : : *
1406 : : * But don't do this if this process was the most recent one to
1407 : : * perform a synchronous write. We do this to detect the case where a
1408 : : * single process is doing a stream of sync writes. No point in waiting
1409 : : * for joiners in that case.
1410 : : */
1411 : 0 : pid = current->pid;
1412 [ # # ][ # # ]: 0 : if (handle->h_sync && journal->j_last_sync_writer != pid) {
1413 : : u64 commit_time, trans_time;
1414 : :
1415 : 0 : journal->j_last_sync_writer = pid;
1416 : :
1417 : : spin_lock(&journal->j_state_lock);
1418 : 0 : commit_time = journal->j_average_commit_time;
1419 : : spin_unlock(&journal->j_state_lock);
1420 : :
1421 : 0 : trans_time = ktime_to_ns(ktime_sub(ktime_get(),
1422 : : transaction->t_start_time));
1423 : :
1424 : 0 : commit_time = min_t(u64, commit_time,
1425 : : 1000*jiffies_to_usecs(1));
1426 : :
1427 [ # # ]: 0 : if (trans_time < commit_time) {
1428 : 0 : ktime_t expires = ktime_add_ns(ktime_get(),
1429 : : commit_time);
1430 : 0 : set_current_state(TASK_UNINTERRUPTIBLE);
1431 : 0 : schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
1432 : : }
1433 : : }
1434 : :
1435 : 0 : current->journal_info = NULL;
1436 : : spin_lock(&journal->j_state_lock);
1437 : : spin_lock(&transaction->t_handle_lock);
1438 : 0 : transaction->t_outstanding_credits -= handle->h_buffer_credits;
1439 : 0 : transaction->t_updates--;
1440 [ # # ]: 0 : if (!transaction->t_updates) {
1441 : 0 : wake_up(&journal->j_wait_updates);
1442 [ # # ]: 0 : if (journal->j_barrier_count)
1443 : 0 : wake_up(&journal->j_wait_transaction_locked);
1444 : : }
1445 : :
1446 : : /*
1447 : : * If the handle is marked SYNC, we need to set another commit
1448 : : * going! We also want to force a commit if the current
1449 : : * transaction is occupying too much of the log, or if the
1450 : : * transaction is too old now.
1451 : : */
1452 [ # # ][ # # ]: 0 : if (handle->h_sync ||
1453 : 0 : transaction->t_outstanding_credits >
1454 : 0 : journal->j_max_transaction_buffers ||
1455 [ # # ]: 0 : time_after_eq(jiffies, transaction->t_expires)) {
1456 : : /* Do this even for aborted journals: an abort still
1457 : : * completes the commit thread, it just doesn't write
1458 : : * anything to disk. */
1459 : 0 : tid_t tid = transaction->t_tid;
1460 : :
1461 : : spin_unlock(&transaction->t_handle_lock);
1462 : : jbd_debug(2, "transaction too old, requesting commit for "
1463 : : "handle %p\n", handle);
1464 : : /* This is non-blocking */
1465 : 0 : __log_start_commit(journal, transaction->t_tid);
1466 : : spin_unlock(&journal->j_state_lock);
1467 : :
1468 : : /*
1469 : : * Special case: JFS_SYNC synchronous updates require us
1470 : : * to wait for the commit to complete.
1471 : : */
1472 [ # # ][ # # ]: 0 : if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1473 : 0 : err = log_wait_commit(journal, tid);
1474 : : } else {
1475 : : spin_unlock(&transaction->t_handle_lock);
1476 : : spin_unlock(&journal->j_state_lock);
1477 : : }
1478 : :
1479 : : lock_map_release(&handle->h_lockdep_map);
1480 : :
1481 : : jbd_free_handle(handle);
1482 : 0 : return err;
1483 : : }
1484 : :
1485 : : /**
1486 : : * int journal_force_commit() - force any uncommitted transactions
1487 : : * @journal: journal to force
1488 : : *
1489 : : * For synchronous operations: force any uncommitted transactions
1490 : : * to disk. May seem kludgy, but it reuses all the handle batching
1491 : : * code in a very simple manner.
1492 : : */
1493 : 0 : int journal_force_commit(journal_t *journal)
1494 : : {
1495 : : handle_t *handle;
1496 : : int ret;
1497 : :
1498 : 0 : handle = journal_start(journal, 1);
1499 [ # # ]: 0 : if (IS_ERR(handle)) {
1500 : : ret = PTR_ERR(handle);
1501 : : } else {
1502 : 0 : handle->h_sync = 1;
1503 : 0 : ret = journal_stop(handle);
1504 : : }
1505 : 0 : return ret;
1506 : : }
1507 : :
1508 : : /*
1509 : : *
1510 : : * List management code snippets: various functions for manipulating the
1511 : : * transaction buffer lists.
1512 : : *
1513 : : */
1514 : :
1515 : : /*
1516 : : * Append a buffer to a transaction list, given the transaction's list head
1517 : : * pointer.
1518 : : *
1519 : : * j_list_lock is held.
1520 : : *
1521 : : * jbd_lock_bh_state(jh2bh(jh)) is held.
1522 : : */
1523 : :
1524 : : static inline void
1525 : : __blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1526 : : {
1527 [ # # ]: 0 : if (!*list) {
1528 : 0 : jh->b_tnext = jh->b_tprev = jh;
1529 : 0 : *list = jh;
1530 : : } else {
1531 : : /* Insert at the tail of the list to preserve order */
1532 : 0 : struct journal_head *first = *list, *last = first->b_tprev;
1533 : 0 : jh->b_tprev = last;
1534 : 0 : jh->b_tnext = first;
1535 : 0 : last->b_tnext = first->b_tprev = jh;
1536 : : }
1537 : : }
1538 : :
1539 : : /*
1540 : : * Remove a buffer from a transaction list, given the transaction's list
1541 : : * head pointer.
1542 : : *
1543 : : * Called with j_list_lock held, and the journal may not be locked.
1544 : : *
1545 : : * jbd_lock_bh_state(jh2bh(jh)) is held.
1546 : : */
1547 : :
1548 : : static inline void
1549 : : __blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1550 : : {
1551 [ # # ]: 0 : if (*list == jh) {
1552 : 0 : *list = jh->b_tnext;
1553 [ # # ]: 0 : if (*list == jh)
1554 : 0 : *list = NULL;
1555 : : }
1556 : 0 : jh->b_tprev->b_tnext = jh->b_tnext;
1557 : 0 : jh->b_tnext->b_tprev = jh->b_tprev;
1558 : : }
1559 : :
1560 : : /*
1561 : : * Remove a buffer from the appropriate transaction list.
1562 : : *
1563 : : * Note that this function can *change* the value of
1564 : : * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1565 : : * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller
1566 : : * is holding onto a copy of one of thee pointers, it could go bad.
1567 : : * Generally the caller needs to re-read the pointer from the transaction_t.
1568 : : *
1569 : : * Called under j_list_lock. The journal may not be locked.
1570 : : */
1571 : 0 : static void __journal_temp_unlink_buffer(struct journal_head *jh)
1572 : : {
1573 : : struct journal_head **list = NULL;
1574 : : transaction_t *transaction;
1575 : : struct buffer_head *bh = jh2bh(jh);
1576 : :
1577 [ # # ]: 0 : J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1578 : 0 : transaction = jh->b_transaction;
1579 [ # # ]: 0 : if (transaction)
1580 [ # # ]: 0 : assert_spin_locked(&transaction->t_journal->j_list_lock);
1581 : :
1582 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1583 [ # # ]: 0 : if (jh->b_jlist != BJ_None)
1584 [ # # ]: 0 : J_ASSERT_JH(jh, transaction != NULL);
1585 : :
1586 [ # # # # : 0 : switch (jh->b_jlist) {
# # # # #
# ]
1587 : : case BJ_None:
1588 : 0 : return;
1589 : : case BJ_SyncData:
1590 : 0 : list = &transaction->t_sync_datalist;
1591 : 0 : break;
1592 : : case BJ_Metadata:
1593 : 0 : transaction->t_nr_buffers--;
1594 [ # # ]: 0 : J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1595 : 0 : list = &transaction->t_buffers;
1596 : 0 : break;
1597 : : case BJ_Forget:
1598 : 0 : list = &transaction->t_forget;
1599 : 0 : break;
1600 : : case BJ_IO:
1601 : 0 : list = &transaction->t_iobuf_list;
1602 : 0 : break;
1603 : : case BJ_Shadow:
1604 : 0 : list = &transaction->t_shadow_list;
1605 : 0 : break;
1606 : : case BJ_LogCtl:
1607 : 0 : list = &transaction->t_log_list;
1608 : 0 : break;
1609 : : case BJ_Reserved:
1610 : 0 : list = &transaction->t_reserved_list;
1611 : 0 : break;
1612 : : case BJ_Locked:
1613 : 0 : list = &transaction->t_locked_list;
1614 : 0 : break;
1615 : : }
1616 : :
1617 : : __blist_del_buffer(list, jh);
1618 : 0 : jh->b_jlist = BJ_None;
1619 [ # # ]: 0 : if (test_clear_buffer_jbddirty(bh))
1620 : 0 : mark_buffer_dirty(bh); /* Expose it to the VM */
1621 : : }
1622 : :
1623 : : /*
1624 : : * Remove buffer from all transactions.
1625 : : *
1626 : : * Called with bh_state lock and j_list_lock
1627 : : *
1628 : : * jh and bh may be already freed when this function returns.
1629 : : */
1630 : 0 : void __journal_unfile_buffer(struct journal_head *jh)
1631 : : {
1632 : 0 : __journal_temp_unlink_buffer(jh);
1633 : 0 : jh->b_transaction = NULL;
1634 : 0 : journal_put_journal_head(jh);
1635 : 0 : }
1636 : :
1637 : 0 : void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1638 : : {
1639 : : struct buffer_head *bh = jh2bh(jh);
1640 : :
1641 : : /* Get reference so that buffer cannot be freed before we unlock it */
1642 : : get_bh(bh);
1643 : : jbd_lock_bh_state(bh);
1644 : : spin_lock(&journal->j_list_lock);
1645 : : __journal_unfile_buffer(jh);
1646 : : spin_unlock(&journal->j_list_lock);
1647 : : jbd_unlock_bh_state(bh);
1648 : 0 : __brelse(bh);
1649 : 0 : }
1650 : :
1651 : : /*
1652 : : * Called from journal_try_to_free_buffers().
1653 : : *
1654 : : * Called under jbd_lock_bh_state(bh)
1655 : : */
1656 : : static void
1657 : 0 : __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1658 : : {
1659 : : struct journal_head *jh;
1660 : :
1661 : : jh = bh2jh(bh);
1662 : :
1663 [ # # ][ # # ]: 0 : if (buffer_locked(bh) || buffer_dirty(bh))
1664 : : goto out;
1665 : :
1666 [ # # ]: 0 : if (jh->b_next_transaction != NULL)
1667 : : goto out;
1668 : :
1669 : : spin_lock(&journal->j_list_lock);
1670 [ # # ][ # # ]: 0 : if (jh->b_transaction != NULL && jh->b_cp_transaction == NULL) {
1671 [ # # ]: 0 : if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1672 : : /* A written-back ordered data buffer */
1673 : : JBUFFER_TRACE(jh, "release data");
1674 : : __journal_unfile_buffer(jh);
1675 : : }
1676 [ # # ][ # # ]: 0 : } else if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
1677 : : /* written-back checkpointed metadata buffer */
1678 [ # # ]: 0 : if (jh->b_jlist == BJ_None) {
1679 : : JBUFFER_TRACE(jh, "remove from checkpoint list");
1680 : 0 : __journal_remove_checkpoint(jh);
1681 : : }
1682 : : }
1683 : : spin_unlock(&journal->j_list_lock);
1684 : : out:
1685 : 0 : return;
1686 : : }
1687 : :
1688 : : /**
1689 : : * int journal_try_to_free_buffers() - try to free page buffers.
1690 : : * @journal: journal for operation
1691 : : * @page: to try and free
1692 : : * @gfp_mask: we use the mask to detect how hard should we try to release
1693 : : * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
1694 : : * release the buffers.
1695 : : *
1696 : : *
1697 : : * For all the buffers on this page,
1698 : : * if they are fully written out ordered data, move them onto BUF_CLEAN
1699 : : * so try_to_free_buffers() can reap them.
1700 : : *
1701 : : * This function returns non-zero if we wish try_to_free_buffers()
1702 : : * to be called. We do this if the page is releasable by try_to_free_buffers().
1703 : : * We also do it if the page has locked or dirty buffers and the caller wants
1704 : : * us to perform sync or async writeout.
1705 : : *
1706 : : * This complicates JBD locking somewhat. We aren't protected by the
1707 : : * BKL here. We wish to remove the buffer from its committing or
1708 : : * running transaction's ->t_datalist via __journal_unfile_buffer.
1709 : : *
1710 : : * This may *change* the value of transaction_t->t_datalist, so anyone
1711 : : * who looks at t_datalist needs to lock against this function.
1712 : : *
1713 : : * Even worse, someone may be doing a journal_dirty_data on this
1714 : : * buffer. So we need to lock against that. journal_dirty_data()
1715 : : * will come out of the lock with the buffer dirty, which makes it
1716 : : * ineligible for release here.
1717 : : *
1718 : : * Who else is affected by this? hmm... Really the only contender
1719 : : * is do_get_write_access() - it could be looking at the buffer while
1720 : : * journal_try_to_free_buffer() is changing its state. But that
1721 : : * cannot happen because we never reallocate freed data as metadata
1722 : : * while the data is part of a transaction. Yes?
1723 : : *
1724 : : * Return 0 on failure, 1 on success
1725 : : */
1726 : 0 : int journal_try_to_free_buffers(journal_t *journal,
1727 : : struct page *page, gfp_t gfp_mask)
1728 : : {
1729 : : struct buffer_head *head;
1730 : : struct buffer_head *bh;
1731 : : int ret = 0;
1732 : :
1733 [ # # ]: 0 : J_ASSERT(PageLocked(page));
1734 : :
1735 [ # # ]: 0 : head = page_buffers(page);
1736 : : bh = head;
1737 : : do {
1738 : : struct journal_head *jh;
1739 : :
1740 : : /*
1741 : : * We take our own ref against the journal_head here to avoid
1742 : : * having to add tons of locking around each instance of
1743 : : * journal_put_journal_head().
1744 : : */
1745 : 0 : jh = journal_grab_journal_head(bh);
1746 [ # # ]: 0 : if (!jh)
1747 : 0 : continue;
1748 : :
1749 : : jbd_lock_bh_state(bh);
1750 : 0 : __journal_try_to_free_buffer(journal, bh);
1751 : 0 : journal_put_journal_head(jh);
1752 : : jbd_unlock_bh_state(bh);
1753 [ # # ]: 0 : if (buffer_jbd(bh))
1754 : : goto busy;
1755 [ # # ]: 0 : } while ((bh = bh->b_this_page) != head);
1756 : :
1757 : 0 : ret = try_to_free_buffers(page);
1758 : :
1759 : : busy:
1760 : 0 : return ret;
1761 : : }
1762 : :
1763 : : /*
1764 : : * This buffer is no longer needed. If it is on an older transaction's
1765 : : * checkpoint list we need to record it on this transaction's forget list
1766 : : * to pin this buffer (and hence its checkpointing transaction) down until
1767 : : * this transaction commits. If the buffer isn't on a checkpoint list, we
1768 : : * release it.
1769 : : * Returns non-zero if JBD no longer has an interest in the buffer.
1770 : : *
1771 : : * Called under j_list_lock.
1772 : : *
1773 : : * Called under jbd_lock_bh_state(bh).
1774 : : */
1775 : 0 : static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1776 : : {
1777 : : int may_free = 1;
1778 : : struct buffer_head *bh = jh2bh(jh);
1779 : :
1780 [ # # ]: 0 : if (jh->b_cp_transaction) {
1781 : : JBUFFER_TRACE(jh, "on running+cp transaction");
1782 : 0 : __journal_temp_unlink_buffer(jh);
1783 : : /*
1784 : : * We don't want to write the buffer anymore, clear the
1785 : : * bit so that we don't confuse checks in
1786 : : * __journal_file_buffer
1787 : : */
1788 : : clear_buffer_dirty(bh);
1789 : 0 : __journal_file_buffer(jh, transaction, BJ_Forget);
1790 : : may_free = 0;
1791 : : } else {
1792 : : JBUFFER_TRACE(jh, "on running transaction");
1793 : : __journal_unfile_buffer(jh);
1794 : : }
1795 : 0 : return may_free;
1796 : : }
1797 : :
1798 : : /*
1799 : : * journal_invalidatepage
1800 : : *
1801 : : * This code is tricky. It has a number of cases to deal with.
1802 : : *
1803 : : * There are two invariants which this code relies on:
1804 : : *
1805 : : * i_size must be updated on disk before we start calling invalidatepage on the
1806 : : * data.
1807 : : *
1808 : : * This is done in ext3 by defining an ext3_setattr method which
1809 : : * updates i_size before truncate gets going. By maintaining this
1810 : : * invariant, we can be sure that it is safe to throw away any buffers
1811 : : * attached to the current transaction: once the transaction commits,
1812 : : * we know that the data will not be needed.
1813 : : *
1814 : : * Note however that we can *not* throw away data belonging to the
1815 : : * previous, committing transaction!
1816 : : *
1817 : : * Any disk blocks which *are* part of the previous, committing
1818 : : * transaction (and which therefore cannot be discarded immediately) are
1819 : : * not going to be reused in the new running transaction
1820 : : *
1821 : : * The bitmap committed_data images guarantee this: any block which is
1822 : : * allocated in one transaction and removed in the next will be marked
1823 : : * as in-use in the committed_data bitmap, so cannot be reused until
1824 : : * the next transaction to delete the block commits. This means that
1825 : : * leaving committing buffers dirty is quite safe: the disk blocks
1826 : : * cannot be reallocated to a different file and so buffer aliasing is
1827 : : * not possible.
1828 : : *
1829 : : *
1830 : : * The above applies mainly to ordered data mode. In writeback mode we
1831 : : * don't make guarantees about the order in which data hits disk --- in
1832 : : * particular we don't guarantee that new dirty data is flushed before
1833 : : * transaction commit --- so it is always safe just to discard data
1834 : : * immediately in that mode. --sct
1835 : : */
1836 : :
1837 : : /*
1838 : : * The journal_unmap_buffer helper function returns zero if the buffer
1839 : : * concerned remains pinned as an anonymous buffer belonging to an older
1840 : : * transaction.
1841 : : *
1842 : : * We're outside-transaction here. Either or both of j_running_transaction
1843 : : * and j_committing_transaction may be NULL.
1844 : : */
1845 : 0 : static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
1846 : : int partial_page)
1847 : : {
1848 : : transaction_t *transaction;
1849 : : struct journal_head *jh;
1850 : : int may_free = 1;
1851 : :
1852 : : BUFFER_TRACE(bh, "entry");
1853 : :
1854 : : retry:
1855 : : /*
1856 : : * It is safe to proceed here without the j_list_lock because the
1857 : : * buffers cannot be stolen by try_to_free_buffers as long as we are
1858 : : * holding the page lock. --sct
1859 : : */
1860 : :
1861 [ # # ]: 0 : if (!buffer_jbd(bh))
1862 : : goto zap_buffer_unlocked;
1863 : :
1864 : : spin_lock(&journal->j_state_lock);
1865 : : jbd_lock_bh_state(bh);
1866 : : spin_lock(&journal->j_list_lock);
1867 : :
1868 : 0 : jh = journal_grab_journal_head(bh);
1869 [ # # ]: 0 : if (!jh)
1870 : : goto zap_buffer_no_jh;
1871 : :
1872 : : /*
1873 : : * We cannot remove the buffer from checkpoint lists until the
1874 : : * transaction adding inode to orphan list (let's call it T)
1875 : : * is committed. Otherwise if the transaction changing the
1876 : : * buffer would be cleaned from the journal before T is
1877 : : * committed, a crash will cause that the correct contents of
1878 : : * the buffer will be lost. On the other hand we have to
1879 : : * clear the buffer dirty bit at latest at the moment when the
1880 : : * transaction marking the buffer as freed in the filesystem
1881 : : * structures is committed because from that moment on the
1882 : : * block can be reallocated and used by a different page.
1883 : : * Since the block hasn't been freed yet but the inode has
1884 : : * already been added to orphan list, it is safe for us to add
1885 : : * the buffer to BJ_Forget list of the newest transaction.
1886 : : *
1887 : : * Also we have to clear buffer_mapped flag of a truncated buffer
1888 : : * because the buffer_head may be attached to the page straddling
1889 : : * i_size (can happen only when blocksize < pagesize) and thus the
1890 : : * buffer_head can be reused when the file is extended again. So we end
1891 : : * up keeping around invalidated buffers attached to transactions'
1892 : : * BJ_Forget list just to stop checkpointing code from cleaning up
1893 : : * the transaction this buffer was modified in.
1894 : : */
1895 : 0 : transaction = jh->b_transaction;
1896 [ # # ]: 0 : if (transaction == NULL) {
1897 : : /* First case: not on any transaction. If it
1898 : : * has no checkpoint link, then we can zap it:
1899 : : * it's a writeback-mode buffer so we don't care
1900 : : * if it hits disk safely. */
1901 [ # # ]: 0 : if (!jh->b_cp_transaction) {
1902 : : JBUFFER_TRACE(jh, "not on any transaction: zap");
1903 : : goto zap_buffer;
1904 : : }
1905 : :
1906 [ # # ]: 0 : if (!buffer_dirty(bh)) {
1907 : : /* bdflush has written it. We can drop it now */
1908 : : goto zap_buffer;
1909 : : }
1910 : :
1911 : : /* OK, it must be in the journal but still not
1912 : : * written fully to disk: it's metadata or
1913 : : * journaled data... */
1914 : :
1915 [ # # ]: 0 : if (journal->j_running_transaction) {
1916 : : /* ... and once the current transaction has
1917 : : * committed, the buffer won't be needed any
1918 : : * longer. */
1919 : : JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1920 : 0 : may_free = __dispose_buffer(jh,
1921 : : journal->j_running_transaction);
1922 : 0 : goto zap_buffer;
1923 : : } else {
1924 : : /* There is no currently-running transaction. So the
1925 : : * orphan record which we wrote for this file must have
1926 : : * passed into commit. We must attach this buffer to
1927 : : * the committing transaction, if it exists. */
1928 [ # # ]: 0 : if (journal->j_committing_transaction) {
1929 : : JBUFFER_TRACE(jh, "give to committing trans");
1930 : 0 : may_free = __dispose_buffer(jh,
1931 : : journal->j_committing_transaction);
1932 : 0 : goto zap_buffer;
1933 : : } else {
1934 : : /* The orphan record's transaction has
1935 : : * committed. We can cleanse this buffer */
1936 : : clear_buffer_jbddirty(bh);
1937 : : goto zap_buffer;
1938 : : }
1939 : : }
1940 [ # # ]: 0 : } else if (transaction == journal->j_committing_transaction) {
1941 : : JBUFFER_TRACE(jh, "on committing transaction");
1942 [ # # ]: 0 : if (jh->b_jlist == BJ_Locked) {
1943 : : /*
1944 : : * The buffer is on the committing transaction's locked
1945 : : * list. We have the buffer locked, so I/O has
1946 : : * completed. So we can nail the buffer now.
1947 : : */
1948 : 0 : may_free = __dispose_buffer(jh, transaction);
1949 : 0 : goto zap_buffer;
1950 : : }
1951 : : /*
1952 : : * The buffer is committing, we simply cannot touch
1953 : : * it. If the page is straddling i_size we have to wait
1954 : : * for commit and try again.
1955 : : */
1956 [ # # ]: 0 : if (partial_page) {
1957 : 0 : tid_t tid = journal->j_committing_transaction->t_tid;
1958 : :
1959 : 0 : journal_put_journal_head(jh);
1960 : : spin_unlock(&journal->j_list_lock);
1961 : : jbd_unlock_bh_state(bh);
1962 : : spin_unlock(&journal->j_state_lock);
1963 : 0 : unlock_buffer(bh);
1964 : 0 : log_wait_commit(journal, tid);
1965 : : lock_buffer(bh);
1966 : : goto retry;
1967 : : }
1968 : : /*
1969 : : * OK, buffer won't be reachable after truncate. We just set
1970 : : * j_next_transaction to the running transaction (if there is
1971 : : * one) and mark buffer as freed so that commit code knows it
1972 : : * should clear dirty bits when it is done with the buffer.
1973 : : */
1974 : : set_buffer_freed(bh);
1975 [ # # ][ # # ]: 0 : if (journal->j_running_transaction && buffer_jbddirty(bh))
1976 : 0 : jh->b_next_transaction = journal->j_running_transaction;
1977 : 0 : journal_put_journal_head(jh);
1978 : : spin_unlock(&journal->j_list_lock);
1979 : : jbd_unlock_bh_state(bh);
1980 : : spin_unlock(&journal->j_state_lock);
1981 : 0 : return 0;
1982 : : } else {
1983 : : /* Good, the buffer belongs to the running transaction.
1984 : : * We are writing our own transaction's data, not any
1985 : : * previous one's, so it is safe to throw it away
1986 : : * (remember that we expect the filesystem to have set
1987 : : * i_size already for this truncate so recovery will not
1988 : : * expose the disk blocks we are discarding here.) */
1989 [ # # ]: 0 : J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1990 : : JBUFFER_TRACE(jh, "on running transaction");
1991 : 0 : may_free = __dispose_buffer(jh, transaction);
1992 : : }
1993 : :
1994 : : zap_buffer:
1995 : : /*
1996 : : * This is tricky. Although the buffer is truncated, it may be reused
1997 : : * if blocksize < pagesize and it is attached to the page straddling
1998 : : * EOF. Since the buffer might have been added to BJ_Forget list of the
1999 : : * running transaction, journal_get_write_access() won't clear
2000 : : * b_modified and credit accounting gets confused. So clear b_modified
2001 : : * here. */
2002 : 0 : jh->b_modified = 0;
2003 : 0 : journal_put_journal_head(jh);
2004 : : zap_buffer_no_jh:
2005 : : spin_unlock(&journal->j_list_lock);
2006 : : jbd_unlock_bh_state(bh);
2007 : : spin_unlock(&journal->j_state_lock);
2008 : : zap_buffer_unlocked:
2009 : : clear_buffer_dirty(bh);
2010 [ # # ]: 0 : J_ASSERT_BH(bh, !buffer_jbddirty(bh));
2011 : : clear_buffer_mapped(bh);
2012 : : clear_buffer_req(bh);
2013 : : clear_buffer_new(bh);
2014 : 0 : bh->b_bdev = NULL;
2015 : 0 : return may_free;
2016 : : }
2017 : :
2018 : : /**
2019 : : * void journal_invalidatepage() - invalidate a journal page
2020 : : * @journal: journal to use for flush
2021 : : * @page: page to flush
2022 : : * @offset: offset of the range to invalidate
2023 : : * @length: length of the range to invalidate
2024 : : *
2025 : : * Reap page buffers containing data in specified range in page.
2026 : : */
2027 : 0 : void journal_invalidatepage(journal_t *journal,
2028 : : struct page *page,
2029 : : unsigned int offset,
2030 : : unsigned int length)
2031 : : {
2032 : : struct buffer_head *head, *bh, *next;
2033 : 0 : unsigned int stop = offset + length;
2034 : : unsigned int curr_off = 0;
2035 : 0 : int partial_page = (offset || length < PAGE_CACHE_SIZE);
2036 : : int may_free = 1;
2037 : :
2038 [ # # ]: 0 : if (!PageLocked(page))
2039 : 0 : BUG();
2040 [ # # ]: 0 : if (!page_has_buffers(page))
2041 : : return;
2042 : :
2043 [ # # ]: 0 : BUG_ON(stop > PAGE_CACHE_SIZE || stop < length);
2044 : :
2045 : : /* We will potentially be playing with lists other than just the
2046 : : * data lists (especially for journaled data mode), so be
2047 : : * cautious in our locking. */
2048 : :
2049 [ # # ]: 0 : head = bh = page_buffers(page);
2050 : : do {
2051 : 0 : unsigned int next_off = curr_off + bh->b_size;
2052 : 0 : next = bh->b_this_page;
2053 : :
2054 [ # # ]: 0 : if (next_off > stop)
2055 : : return;
2056 : :
2057 [ # # ]: 0 : if (offset <= curr_off) {
2058 : : /* This block is wholly outside the truncation point */
2059 : : lock_buffer(bh);
2060 : 0 : may_free &= journal_unmap_buffer(journal, bh,
2061 : : partial_page);
2062 : 0 : unlock_buffer(bh);
2063 : : }
2064 : : curr_off = next_off;
2065 : : bh = next;
2066 : :
2067 [ # # ]: 0 : } while (bh != head);
2068 : :
2069 [ # # ]: 0 : if (!partial_page) {
2070 [ # # ][ # # ]: 0 : if (may_free && try_to_free_buffers(page))
2071 [ # # ]: 0 : J_ASSERT(!page_has_buffers(page));
2072 : : }
2073 : : }
2074 : :
2075 : : /*
2076 : : * File a buffer on the given transaction list.
2077 : : */
2078 : 0 : void __journal_file_buffer(struct journal_head *jh,
2079 : : transaction_t *transaction, int jlist)
2080 : : {
2081 : : struct journal_head **list = NULL;
2082 : : int was_dirty = 0;
2083 : 0 : struct buffer_head *bh = jh2bh(jh);
2084 : :
2085 [ # # ]: 0 : J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2086 [ # # ]: 0 : assert_spin_locked(&transaction->t_journal->j_list_lock);
2087 : :
2088 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
2089 [ # # ][ # # ]: 0 : J_ASSERT_JH(jh, jh->b_transaction == transaction ||
2090 : : jh->b_transaction == NULL);
2091 : :
2092 [ # # ][ # # ]: 0 : if (jh->b_transaction && jh->b_jlist == jlist)
2093 : : return;
2094 : :
2095 [ # # ]: 0 : if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
2096 [ # # ]: 0 : jlist == BJ_Shadow || jlist == BJ_Forget) {
2097 : : /*
2098 : : * For metadata buffers, we track dirty bit in buffer_jbddirty
2099 : : * instead of buffer_dirty. We should not see a dirty bit set
2100 : : * here because we clear it in do_get_write_access but e.g.
2101 : : * tune2fs can modify the sb and set the dirty bit at any time
2102 : : * so we try to gracefully handle that.
2103 : : */
2104 [ # # ]: 0 : if (buffer_dirty(bh))
2105 : 0 : warn_dirty_buffer(bh);
2106 [ # # # # ]: 0 : if (test_clear_buffer_dirty(bh) ||
2107 : : test_clear_buffer_jbddirty(bh))
2108 : : was_dirty = 1;
2109 : : }
2110 : :
2111 [ # # ]: 0 : if (jh->b_transaction)
2112 : 0 : __journal_temp_unlink_buffer(jh);
2113 : : else
2114 : 0 : journal_grab_journal_head(bh);
2115 : 0 : jh->b_transaction = transaction;
2116 : :
2117 [ # # # # : 0 : switch (jlist) {
# # # # #
# ]
2118 : : case BJ_None:
2119 [ # # ]: 0 : J_ASSERT_JH(jh, !jh->b_committed_data);
2120 [ # # ]: 0 : J_ASSERT_JH(jh, !jh->b_frozen_data);
2121 : : return;
2122 : : case BJ_SyncData:
2123 : 0 : list = &transaction->t_sync_datalist;
2124 : 0 : break;
2125 : : case BJ_Metadata:
2126 : 0 : transaction->t_nr_buffers++;
2127 : 0 : list = &transaction->t_buffers;
2128 : 0 : break;
2129 : : case BJ_Forget:
2130 : 0 : list = &transaction->t_forget;
2131 : 0 : break;
2132 : : case BJ_IO:
2133 : 0 : list = &transaction->t_iobuf_list;
2134 : 0 : break;
2135 : : case BJ_Shadow:
2136 : 0 : list = &transaction->t_shadow_list;
2137 : 0 : break;
2138 : : case BJ_LogCtl:
2139 : 0 : list = &transaction->t_log_list;
2140 : 0 : break;
2141 : : case BJ_Reserved:
2142 : 0 : list = &transaction->t_reserved_list;
2143 : 0 : break;
2144 : : case BJ_Locked:
2145 : 0 : list = &transaction->t_locked_list;
2146 : 0 : break;
2147 : : }
2148 : :
2149 : : __blist_add_buffer(list, jh);
2150 : 0 : jh->b_jlist = jlist;
2151 : :
2152 [ # # ]: 0 : if (was_dirty)
2153 : : set_buffer_jbddirty(bh);
2154 : : }
2155 : :
2156 : 0 : void journal_file_buffer(struct journal_head *jh,
2157 : : transaction_t *transaction, int jlist)
2158 : : {
2159 : : jbd_lock_bh_state(jh2bh(jh));
2160 : 0 : spin_lock(&transaction->t_journal->j_list_lock);
2161 : 0 : __journal_file_buffer(jh, transaction, jlist);
2162 : 0 : spin_unlock(&transaction->t_journal->j_list_lock);
2163 : : jbd_unlock_bh_state(jh2bh(jh));
2164 : 0 : }
2165 : :
2166 : : /*
2167 : : * Remove a buffer from its current buffer list in preparation for
2168 : : * dropping it from its current transaction entirely. If the buffer has
2169 : : * already started to be used by a subsequent transaction, refile the
2170 : : * buffer on that transaction's metadata list.
2171 : : *
2172 : : * Called under j_list_lock
2173 : : * Called under jbd_lock_bh_state(jh2bh(jh))
2174 : : *
2175 : : * jh and bh may be already free when this function returns
2176 : : */
2177 : 0 : void __journal_refile_buffer(struct journal_head *jh)
2178 : : {
2179 : : int was_dirty, jlist;
2180 : : struct buffer_head *bh = jh2bh(jh);
2181 : :
2182 [ # # ]: 0 : J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2183 [ # # ]: 0 : if (jh->b_transaction)
2184 [ # # ]: 0 : assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2185 : :
2186 : : /* If the buffer is now unused, just drop it. */
2187 [ # # ]: 0 : if (jh->b_next_transaction == NULL) {
2188 : : __journal_unfile_buffer(jh);
2189 : 0 : return;
2190 : : }
2191 : :
2192 : : /*
2193 : : * It has been modified by a later transaction: add it to the new
2194 : : * transaction's metadata list.
2195 : : */
2196 : :
2197 : : was_dirty = test_clear_buffer_jbddirty(bh);
2198 : 0 : __journal_temp_unlink_buffer(jh);
2199 : : /*
2200 : : * We set b_transaction here because b_next_transaction will inherit
2201 : : * our jh reference and thus __journal_file_buffer() must not take a
2202 : : * new one.
2203 : : */
2204 : 0 : jh->b_transaction = jh->b_next_transaction;
2205 : 0 : jh->b_next_transaction = NULL;
2206 [ # # ]: 0 : if (buffer_freed(bh))
2207 : : jlist = BJ_Forget;
2208 [ # # ]: 0 : else if (jh->b_modified)
2209 : : jlist = BJ_Metadata;
2210 : : else
2211 : : jlist = BJ_Reserved;
2212 : 0 : __journal_file_buffer(jh, jh->b_transaction, jlist);
2213 [ # # ]: 0 : J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2214 : :
2215 [ # # ]: 0 : if (was_dirty)
2216 : : set_buffer_jbddirty(bh);
2217 : : }
2218 : :
2219 : : /*
2220 : : * __journal_refile_buffer() with necessary locking added. We take our bh
2221 : : * reference so that we can safely unlock bh.
2222 : : *
2223 : : * The jh and bh may be freed by this call.
2224 : : */
2225 : 0 : void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2226 : : {
2227 : : struct buffer_head *bh = jh2bh(jh);
2228 : :
2229 : : /* Get reference so that buffer cannot be freed before we unlock it */
2230 : : get_bh(bh);
2231 : : jbd_lock_bh_state(bh);
2232 : : spin_lock(&journal->j_list_lock);
2233 : 0 : __journal_refile_buffer(jh);
2234 : : jbd_unlock_bh_state(bh);
2235 : : spin_unlock(&journal->j_list_lock);
2236 : 0 : __brelse(bh);
2237 : 0 : }
|
