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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 | transaction->t_journal = journal; |
52 | transaction->t_state = T_RUNNING; |
53 | transaction->t_start_time = ktime_get(); |
54 | transaction->t_tid = journal->j_transaction_sequence++; |
55 | transaction->t_expires = jiffies + journal->j_commit_interval; |
56 | spin_lock_init(&transaction->t_handle_lock); |
57 | |
58 | /* Set up the commit timer for the new transaction. */ |
59 | journal->j_commit_timer.expires = |
60 | round_jiffies_up(transaction->t_expires); |
61 | add_timer(&journal->j_commit_timer); |
62 | |
63 | J_ASSERT(journal->j_running_transaction == NULL); |
64 | journal->j_running_transaction = transaction; |
65 | |
66 | 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 | transaction_t *transaction; |
87 | int needed; |
88 | int nblocks = handle->h_buffer_credits; |
89 | transaction_t *new_transaction = NULL; |
90 | int ret = 0; |
91 | |
92 | if (nblocks > journal->j_max_transaction_buffers) { |
93 | printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n", |
94 | current->comm, nblocks, |
95 | journal->j_max_transaction_buffers); |
96 | ret = -ENOSPC; |
97 | goto out; |
98 | } |
99 | |
100 | alloc_transaction: |
101 | if (!journal->j_running_transaction) { |
102 | new_transaction = kzalloc(sizeof(*new_transaction), |
103 | GFP_NOFS|__GFP_NOFAIL); |
104 | 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 | if (is_journal_aborted(journal) || |
121 | (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 | if (journal->j_barrier_count) { |
129 | spin_unlock(&journal->j_state_lock); |
130 | wait_event(journal->j_wait_transaction_locked, |
131 | journal->j_barrier_count == 0); |
132 | goto repeat; |
133 | } |
134 | |
135 | if (!journal->j_running_transaction) { |
136 | if (!new_transaction) { |
137 | spin_unlock(&journal->j_state_lock); |
138 | goto alloc_transaction; |
139 | } |
140 | get_transaction(journal, new_transaction); |
141 | new_transaction = NULL; |
142 | } |
143 | |
144 | 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 | if (transaction->t_state == T_LOCKED) { |
151 | DEFINE_WAIT(wait); |
152 | |
153 | prepare_to_wait(&journal->j_wait_transaction_locked, |
154 | &wait, TASK_UNINTERRUPTIBLE); |
155 | spin_unlock(&journal->j_state_lock); |
156 | schedule(); |
157 | 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 | needed = transaction->t_outstanding_credits + nblocks; |
168 | |
169 | 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 | DEFINE_WAIT(wait); |
176 | |
177 | jbd_debug(2, "Handle %p starting new commit...\n", handle); |
178 | spin_unlock(&transaction->t_handle_lock); |
179 | prepare_to_wait(&journal->j_wait_transaction_locked, &wait, |
180 | TASK_UNINTERRUPTIBLE); |
181 | __log_start_commit(journal, transaction->t_tid); |
182 | spin_unlock(&journal->j_state_lock); |
183 | schedule(); |
184 | 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 inconsitent with the matching one in |
211 | * journal_extend(). |
212 | */ |
213 | 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 | __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 | handle->h_transaction = transaction; |
224 | transaction->t_outstanding_credits += nblocks; |
225 | transaction->t_updates++; |
226 | 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 | if (unlikely(new_transaction)) /* It's usually NULL */ |
236 | kfree(new_transaction); |
237 | 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 | handle_t *handle = jbd_alloc_handle(GFP_NOFS); |
246 | if (!handle) |
247 | return NULL; |
248 | memset(handle, 0, sizeof(*handle)); |
249 | handle->h_buffer_credits = nblocks; |
250 | handle->h_ref = 1; |
251 | |
252 | lockdep_init_map(&handle->h_lockdep_map, "jbd_handle", &jbd_handle_key, 0); |
253 | |
254 | 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 | handle_t *handle = journal_current_handle(); |
274 | int err; |
275 | |
276 | if (!journal) |
277 | return ERR_PTR(-EROFS); |
278 | |
279 | if (handle) { |
280 | J_ASSERT(handle->h_transaction->t_journal == journal); |
281 | handle->h_ref++; |
282 | return handle; |
283 | } |
284 | |
285 | handle = new_handle(nblocks); |
286 | if (!handle) |
287 | return ERR_PTR(-ENOMEM); |
288 | |
289 | current->journal_info = handle; |
290 | |
291 | err = start_this_handle(journal, handle); |
292 | if (err < 0) { |
293 | jbd_free_handle(handle); |
294 | current->journal_info = NULL; |
295 | handle = ERR_PTR(err); |
296 | goto out; |
297 | } |
298 | out: |
299 | return handle; |
300 | } |
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 | transaction_t *transaction = handle->h_transaction; |
325 | journal_t *journal = transaction->t_journal; |
326 | int result; |
327 | int wanted; |
328 | |
329 | result = -EIO; |
330 | if (is_handle_aborted(handle)) |
331 | goto out; |
332 | |
333 | result = 1; |
334 | |
335 | spin_lock(&journal->j_state_lock); |
336 | |
337 | /* Don't extend a locked-down transaction! */ |
338 | 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 | goto error_out; |
342 | } |
343 | |
344 | spin_lock(&transaction->t_handle_lock); |
345 | wanted = transaction->t_outstanding_credits + nblocks; |
346 | |
347 | if (wanted > journal->j_max_transaction_buffers) { |
348 | jbd_debug(3, "denied handle %p %d blocks: " |
349 | "transaction too large\n", handle, nblocks); |
350 | goto unlock; |
351 | } |
352 | |
353 | if (wanted > __log_space_left(journal)) { |
354 | jbd_debug(3, "denied handle %p %d blocks: " |
355 | "insufficient log space\n", handle, nblocks); |
356 | goto unlock; |
357 | } |
358 | |
359 | handle->h_buffer_credits += nblocks; |
360 | transaction->t_outstanding_credits += nblocks; |
361 | result = 0; |
362 | |
363 | jbd_debug(3, "extended handle %p by %d\n", handle, nblocks); |
364 | unlock: |
365 | spin_unlock(&transaction->t_handle_lock); |
366 | error_out: |
367 | spin_unlock(&journal->j_state_lock); |
368 | out: |
369 | 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 | transaction_t *transaction = handle->h_transaction; |
391 | journal_t *journal = transaction->t_journal; |
392 | int ret; |
393 | |
394 | /* If we've had an abort of any type, don't even think about |
395 | * actually doing the restart! */ |
396 | if (is_handle_aborted(handle)) |
397 | return 0; |
398 | |
399 | /* |
400 | * First unlink the handle from its current transaction, and start the |
401 | * commit on that. |
402 | */ |
403 | J_ASSERT(transaction->t_updates > 0); |
404 | J_ASSERT(journal_current_handle() == handle); |
405 | |
406 | spin_lock(&journal->j_state_lock); |
407 | spin_lock(&transaction->t_handle_lock); |
408 | transaction->t_outstanding_credits -= handle->h_buffer_credits; |
409 | transaction->t_updates--; |
410 | |
411 | if (!transaction->t_updates) |
412 | wake_up(&journal->j_wait_updates); |
413 | spin_unlock(&transaction->t_handle_lock); |
414 | |
415 | jbd_debug(2, "restarting handle %p\n", handle); |
416 | __log_start_commit(journal, transaction->t_tid); |
417 | spin_unlock(&journal->j_state_lock); |
418 | |
419 | lock_map_release(&handle->h_lockdep_map); |
420 | handle->h_buffer_credits = nblocks; |
421 | ret = start_this_handle(journal, handle); |
422 | 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 | DEFINE_WAIT(wait); |
439 | |
440 | spin_lock(&journal->j_state_lock); |
441 | ++journal->j_barrier_count; |
442 | |
443 | /* Wait until there are no running updates */ |
444 | while (1) { |
445 | transaction_t *transaction = journal->j_running_transaction; |
446 | |
447 | if (!transaction) |
448 | break; |
449 | |
450 | spin_lock(&transaction->t_handle_lock); |
451 | if (!transaction->t_updates) { |
452 | spin_unlock(&transaction->t_handle_lock); |
453 | break; |
454 | } |
455 | prepare_to_wait(&journal->j_wait_updates, &wait, |
456 | TASK_UNINTERRUPTIBLE); |
457 | spin_unlock(&transaction->t_handle_lock); |
458 | spin_unlock(&journal->j_state_lock); |
459 | schedule(); |
460 | finish_wait(&journal->j_wait_updates, &wait); |
461 | spin_lock(&journal->j_state_lock); |
462 | } |
463 | 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 | mutex_lock(&journal->j_barrier); |
472 | } |
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 | J_ASSERT(journal->j_barrier_count != 0); |
485 | |
486 | mutex_unlock(&journal->j_barrier); |
487 | spin_lock(&journal->j_state_lock); |
488 | --journal->j_barrier_count; |
489 | spin_unlock(&journal->j_state_lock); |
490 | wake_up(&journal->j_wait_transaction_locked); |
491 | } |
492 | |
493 | static void warn_dirty_buffer(struct buffer_head *bh) |
494 | { |
495 | char b[BDEVNAME_SIZE]; |
496 | |
497 | 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 | } |
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 | { |
518 | struct buffer_head *bh; |
519 | transaction_t *transaction; |
520 | journal_t *journal; |
521 | int error; |
522 | char *frozen_buffer = NULL; |
523 | int need_copy = 0; |
524 | |
525 | if (is_handle_aborted(handle)) |
526 | return -EROFS; |
527 | |
528 | transaction = handle->h_transaction; |
529 | journal = transaction->t_journal; |
530 | |
531 | jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy); |
532 | |
533 | JBUFFER_TRACE(jh, "entry"); |
534 | repeat: |
535 | bh = jh2bh(jh); |
536 | |
537 | /* @@@ Need to check for errors here at some point. */ |
538 | |
539 | lock_buffer(bh); |
540 | jbd_lock_bh_state(bh); |
541 | |
542 | /* We now hold the buffer lock so it is safe to query the buffer |
543 | * state. Is the buffer dirty? |
544 | * |
545 | * If so, there are two possibilities. The buffer may be |
546 | * non-journaled, and undergoing a quite legitimate writeback. |
547 | * Otherwise, it is journaled, and we don't expect dirty buffers |
548 | * 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 | 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 | if (jh->b_transaction) { |
561 | J_ASSERT_JH(jh, |
562 | jh->b_transaction == transaction || |
563 | jh->b_transaction == |
564 | journal->j_committing_transaction); |
565 | if (jh->b_next_transaction) |
566 | J_ASSERT_JH(jh, jh->b_next_transaction == |
567 | transaction); |
568 | 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 | clear_buffer_dirty(bh); |
577 | set_buffer_jbddirty(bh); |
578 | } |
579 | |
580 | unlock_buffer(bh); |
581 | |
582 | error = -EROFS; |
583 | if (is_handle_aborted(handle)) { |
584 | jbd_unlock_bh_state(bh); |
585 | goto out; |
586 | } |
587 | 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 | if (jh->b_transaction == transaction || |
594 | jh->b_next_transaction == transaction) |
595 | goto done; |
596 | |
597 | /* |
598 | * this is the first time this transaction is touching this buffer, |
599 | * reset the modified flag |
600 | */ |
601 | 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 | if (jh->b_frozen_data) { |
608 | JBUFFER_TRACE(jh, "has frozen data"); |
609 | J_ASSERT_JH(jh, jh->b_next_transaction == NULL); |
610 | jh->b_next_transaction = transaction; |
611 | goto done; |
612 | } |
613 | |
614 | /* Is there data here we need to preserve? */ |
615 | |
616 | if (jh->b_transaction && jh->b_transaction != transaction) { |
617 | JBUFFER_TRACE(jh, "owned by older transaction"); |
618 | J_ASSERT_JH(jh, jh->b_next_transaction == NULL); |
619 | 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 | if (jh->b_jlist == BJ_Shadow) { |
632 | DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow); |
633 | wait_queue_head_t *wqh; |
634 | |
635 | wqh = bit_waitqueue(&bh->b_state, BH_Unshadow); |
636 | |
637 | JBUFFER_TRACE(jh, "on shadow: sleep"); |
638 | jbd_unlock_bh_state(bh); |
639 | /* commit wakes up all shadow buffers after IO */ |
640 | for ( ; ; ) { |
641 | prepare_to_wait(wqh, &wait.wait, |
642 | TASK_UNINTERRUPTIBLE); |
643 | if (jh->b_jlist != BJ_Shadow) |
644 | break; |
645 | schedule(); |
646 | } |
647 | finish_wait(wqh, &wait.wait); |
648 | 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 | if (jh->b_jlist != BJ_Forget || force_copy) { |
666 | JBUFFER_TRACE(jh, "generate frozen data"); |
667 | if (!frozen_buffer) { |
668 | JBUFFER_TRACE(jh, "allocate memory for buffer"); |
669 | jbd_unlock_bh_state(bh); |
670 | frozen_buffer = |
671 | jbd_alloc(jh2bh(jh)->b_size, |
672 | GFP_NOFS); |
673 | if (!frozen_buffer) { |
674 | printk(KERN_EMERG |
675 | "%s: OOM for frozen_buffer\n", |
676 | __func__); |
677 | JBUFFER_TRACE(jh, "oom!"); |
678 | error = -ENOMEM; |
679 | jbd_lock_bh_state(bh); |
680 | goto done; |
681 | } |
682 | goto repeat; |
683 | } |
684 | jh->b_frozen_data = frozen_buffer; |
685 | frozen_buffer = NULL; |
686 | need_copy = 1; |
687 | } |
688 | 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 | if (!jh->b_transaction) { |
698 | JBUFFER_TRACE(jh, "no transaction"); |
699 | J_ASSERT_JH(jh, !jh->b_next_transaction); |
700 | jh->b_transaction = transaction; |
701 | JBUFFER_TRACE(jh, "file as BJ_Reserved"); |
702 | spin_lock(&journal->j_list_lock); |
703 | __journal_file_buffer(jh, transaction, BJ_Reserved); |
704 | spin_unlock(&journal->j_list_lock); |
705 | } |
706 | |
707 | done: |
708 | if (need_copy) { |
709 | struct page *page; |
710 | int offset; |
711 | char *source; |
712 | |
713 | J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)), |
714 | "Possible IO failure.\n"); |
715 | page = jh2bh(jh)->b_page; |
716 | offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK; |
717 | source = kmap_atomic(page, KM_USER0); |
718 | memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size); |
719 | kunmap_atomic(source, KM_USER0); |
720 | } |
721 | 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 | journal_cancel_revoke(handle, jh); |
728 | |
729 | out: |
730 | if (unlikely(frozen_buffer)) /* It's usually NULL */ |
731 | jbd_free(frozen_buffer, bh->b_size); |
732 | |
733 | JBUFFER_TRACE(jh, "exit"); |
734 | 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 | struct journal_head *jh = journal_add_journal_head(bh); |
751 | int rc; |
752 | |
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 | rc = do_get_write_access(handle, jh, 0); |
757 | journal_put_journal_head(jh); |
758 | 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 | transaction_t *transaction = handle->h_transaction; |
784 | journal_t *journal = transaction->t_journal; |
785 | struct journal_head *jh = journal_add_journal_head(bh); |
786 | int err; |
787 | |
788 | jbd_debug(5, "journal_head %p\n", jh); |
789 | err = -EROFS; |
790 | if (is_handle_aborted(handle)) |
791 | goto out; |
792 | err = 0; |
793 | |
794 | JBUFFER_TRACE(jh, "entry"); |
795 | /* |
796 | * The buffer may already belong to this transaction due to pre-zeroing |
797 | * in the filesystem's new_block code. It may also be on the previous, |
798 | * committing transaction's lists, but it HAS to be in Forget state in |
799 | * that case: the transaction must have deleted the buffer for it to be |
800 | * reused here. |
801 | */ |
802 | jbd_lock_bh_state(bh); |
803 | spin_lock(&journal->j_list_lock); |
804 | 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 | J_ASSERT_JH(jh, jh->b_next_transaction == NULL); |
810 | J_ASSERT_JH(jh, buffer_locked(jh2bh(jh))); |
811 | |
812 | 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 | clear_buffer_dirty(jh2bh(jh)); |
822 | jh->b_transaction = transaction; |
823 | |
824 | /* first access by this transaction */ |
825 | jh->b_modified = 0; |
826 | |
827 | JBUFFER_TRACE(jh, "file as BJ_Reserved"); |
828 | __journal_file_buffer(jh, transaction, BJ_Reserved); |
829 | } else if (jh->b_transaction == journal->j_committing_transaction) { |
830 | /* first access by this transaction */ |
831 | jh->b_modified = 0; |
832 | |
833 | JBUFFER_TRACE(jh, "set next transaction"); |
834 | jh->b_next_transaction = transaction; |
835 | } |
836 | spin_unlock(&journal->j_list_lock); |
837 | 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 | journal_cancel_revoke(handle, jh); |
848 | journal_put_journal_head(jh); |
849 | out: |
850 | 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 | int err; |
881 | struct journal_head *jh = journal_add_journal_head(bh); |
882 | char *committed_data = NULL; |
883 | |
884 | JBUFFER_TRACE(jh, "entry"); |
885 | |
886 | /* |
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 | err = do_get_write_access(handle, jh, 1); |
892 | if (err) |
893 | goto out; |
894 | |
895 | repeat: |
896 | if (!jh->b_committed_data) { |
897 | committed_data = jbd_alloc(jh2bh(jh)->b_size, GFP_NOFS); |
898 | if (!committed_data) { |
899 | printk(KERN_EMERG "%s: No memory for committed data\n", |
900 | __func__); |
901 | err = -ENOMEM; |
902 | goto out; |
903 | } |
904 | } |
905 | |
906 | jbd_lock_bh_state(bh); |
907 | 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 | if (!committed_data) { |
912 | jbd_unlock_bh_state(bh); |
913 | goto repeat; |
914 | } |
915 | |
916 | jh->b_committed_data = committed_data; |
917 | committed_data = NULL; |
918 | memcpy(jh->b_committed_data, bh->b_data, bh->b_size); |
919 | } |
920 | jbd_unlock_bh_state(bh); |
921 | out: |
922 | journal_put_journal_head(jh); |
923 | if (unlikely(committed_data)) |
924 | jbd_free(committed_data, bh->b_size); |
925 | 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 | journal_t *journal = handle->h_transaction->t_journal; |
948 | int need_brelse = 0; |
949 | struct journal_head *jh; |
950 | int ret = 0; |
951 | |
952 | if (is_handle_aborted(handle)) |
953 | return ret; |
954 | |
955 | jh = journal_add_journal_head(bh); |
956 | JBUFFER_TRACE(jh, "entry"); |
957 | |
958 | /* |
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 | jbd_lock_bh_state(bh); |
986 | spin_lock(&journal->j_list_lock); |
987 | |
988 | /* Now that we have bh_state locked, are we really still mapped? */ |
989 | if (!buffer_mapped(bh)) { |
990 | JBUFFER_TRACE(jh, "unmapped buffer, bailing out"); |
991 | goto no_journal; |
992 | } |
993 | |
994 | if (jh->b_transaction) { |
995 | JBUFFER_TRACE(jh, "has transaction"); |
996 | if (jh->b_transaction != handle->h_transaction) { |
997 | JBUFFER_TRACE(jh, "belongs to older transaction"); |
998 | 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 | 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 | 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 | if (buffer_dirty(bh)) { |
1048 | get_bh(bh); |
1049 | spin_unlock(&journal->j_list_lock); |
1050 | jbd_unlock_bh_state(bh); |
1051 | need_brelse = 1; |
1052 | sync_dirty_buffer(bh); |
1053 | jbd_lock_bh_state(bh); |
1054 | spin_lock(&journal->j_list_lock); |
1055 | /* Since we dropped the lock... */ |
1056 | if (!buffer_mapped(bh)) { |
1057 | JBUFFER_TRACE(jh, "buffer got unmapped"); |
1058 | 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 | if (unlikely(!buffer_uptodate(bh))) { |
1070 | ret = -EIO; |
1071 | goto no_journal; |
1072 | } |
1073 | |
1074 | if (jh->b_transaction != NULL) { |
1075 | JBUFFER_TRACE(jh, "unfile from commit"); |
1076 | __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 | 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 | if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) { |
1093 | JBUFFER_TRACE(jh, "not on correct data list: unfile"); |
1094 | J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow); |
1095 | __journal_temp_unlink_buffer(jh); |
1096 | jh->b_transaction = handle->h_transaction; |
1097 | JBUFFER_TRACE(jh, "file as data"); |
1098 | __journal_file_buffer(jh, handle->h_transaction, |
1099 | BJ_SyncData); |
1100 | } |
1101 | } else { |
1102 | JBUFFER_TRACE(jh, "not on a transaction"); |
1103 | __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData); |
1104 | } |
1105 | no_journal: |
1106 | spin_unlock(&journal->j_list_lock); |
1107 | jbd_unlock_bh_state(bh); |
1108 | if (need_brelse) { |
1109 | BUFFER_TRACE(bh, "brelse"); |
1110 | __brelse(bh); |
1111 | } |
1112 | JBUFFER_TRACE(jh, "exit"); |
1113 | journal_put_journal_head(jh); |
1114 | 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 | transaction_t *transaction = handle->h_transaction; |
1139 | journal_t *journal = transaction->t_journal; |
1140 | struct journal_head *jh = bh2jh(bh); |
1141 | |
1142 | jbd_debug(5, "journal_head %p\n", jh); |
1143 | JBUFFER_TRACE(jh, "entry"); |
1144 | if (is_handle_aborted(handle)) |
1145 | goto out; |
1146 | |
1147 | jbd_lock_bh_state(bh); |
1148 | |
1149 | 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 | jh->b_modified = 1; |
1156 | J_ASSERT_JH(jh, handle->h_buffer_credits > 0); |
1157 | 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 | if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) { |
1168 | JBUFFER_TRACE(jh, "fastpath"); |
1169 | J_ASSERT_JH(jh, jh->b_transaction == |
1170 | journal->j_running_transaction); |
1171 | goto out_unlock_bh; |
1172 | } |
1173 | |
1174 | 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 | if (jh->b_transaction != transaction) { |
1183 | JBUFFER_TRACE(jh, "already on other transaction"); |
1184 | J_ASSERT_JH(jh, jh->b_transaction == |
1185 | journal->j_committing_transaction); |
1186 | 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 | goto out_unlock_bh; |
1190 | } |
1191 | |
1192 | /* That test should have eliminated the following case: */ |
1193 | J_ASSERT_JH(jh, jh->b_frozen_data == NULL); |
1194 | |
1195 | JBUFFER_TRACE(jh, "file as BJ_Metadata"); |
1196 | spin_lock(&journal->j_list_lock); |
1197 | __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata); |
1198 | spin_unlock(&journal->j_list_lock); |
1199 | out_unlock_bh: |
1200 | jbd_unlock_bh_state(bh); |
1201 | out: |
1202 | JBUFFER_TRACE(jh, "exit"); |
1203 | 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 | 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 | transaction_t *transaction = handle->h_transaction; |
1237 | journal_t *journal = transaction->t_journal; |
1238 | struct journal_head *jh; |
1239 | int drop_reserve = 0; |
1240 | int err = 0; |
1241 | int was_modified = 0; |
1242 | |
1243 | BUFFER_TRACE(bh, "entry"); |
1244 | |
1245 | jbd_lock_bh_state(bh); |
1246 | spin_lock(&journal->j_list_lock); |
1247 | |
1248 | if (!buffer_jbd(bh)) |
1249 | goto not_jbd; |
1250 | 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 | if (!J_EXPECT_JH(jh, !jh->b_committed_data, |
1255 | "inconsistent data on disk")) { |
1256 | err = -EIO; |
1257 | goto not_jbd; |
1258 | } |
1259 | |
1260 | /* keep track of wether or not this transaction modified us */ |
1261 | was_modified = jh->b_modified; |
1262 | |
1263 | /* |
1264 | * The buffer's going from the transaction, we must drop |
1265 | * all references -bzzz |
1266 | */ |
1267 | jh->b_modified = 0; |
1268 | |
1269 | if (jh->b_transaction == handle->h_transaction) { |
1270 | 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 | clear_buffer_dirty(bh); |
1276 | 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 | if (was_modified) |
1285 | 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 | if (jh->b_cp_transaction) { |
1300 | __journal_temp_unlink_buffer(jh); |
1301 | __journal_file_buffer(jh, transaction, BJ_Forget); |
1302 | } else { |
1303 | __journal_unfile_buffer(jh); |
1304 | journal_remove_journal_head(bh); |
1305 | __brelse(bh); |
1306 | if (!buffer_jbd(bh)) { |
1307 | spin_unlock(&journal->j_list_lock); |
1308 | jbd_unlock_bh_state(bh); |
1309 | __bforget(bh); |
1310 | goto drop; |
1311 | } |
1312 | } |
1313 | } else if (jh->b_transaction) { |
1314 | 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 | if (jh->b_next_transaction) { |
1323 | J_ASSERT(jh->b_next_transaction == transaction); |
1324 | jh->b_next_transaction = NULL; |
1325 | |
1326 | /* |
1327 | * only drop a reference if this transaction modified |
1328 | * the buffer |
1329 | */ |
1330 | if (was_modified) |
1331 | drop_reserve = 1; |
1332 | } |
1333 | } |
1334 | |
1335 | not_jbd: |
1336 | spin_unlock(&journal->j_list_lock); |
1337 | jbd_unlock_bh_state(bh); |
1338 | __brelse(bh); |
1339 | drop: |
1340 | if (drop_reserve) { |
1341 | /* no need to reserve log space for this block -bzzz */ |
1342 | handle->h_buffer_credits++; |
1343 | } |
1344 | 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 | transaction_t *transaction = handle->h_transaction; |
1366 | journal_t *journal = transaction->t_journal; |
1367 | int err; |
1368 | pid_t pid; |
1369 | |
1370 | J_ASSERT(journal_current_handle() == handle); |
1371 | |
1372 | if (is_handle_aborted(handle)) |
1373 | err = -EIO; |
1374 | else { |
1375 | J_ASSERT(transaction->t_updates > 0); |
1376 | err = 0; |
1377 | } |
1378 | |
1379 | if (--handle->h_ref > 0) { |
1380 | jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1, |
1381 | handle->h_ref); |
1382 | return err; |
1383 | } |
1384 | |
1385 | jbd_debug(4, "Handle %p going down\n", handle); |
1386 | |
1387 | /* |
1388 | * Implement synchronous transaction batching. If the handle |
1389 | * was synchronous, don't force a commit immediately. Let's |
1390 | * 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 achieve 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 | pid = current->pid; |
1413 | if (handle->h_sync && journal->j_last_sync_writer != pid) { |
1414 | u64 commit_time, trans_time; |
1415 | |
1416 | journal->j_last_sync_writer = pid; |
1417 | |
1418 | spin_lock(&journal->j_state_lock); |
1419 | commit_time = journal->j_average_commit_time; |
1420 | spin_unlock(&journal->j_state_lock); |
1421 | |
1422 | trans_time = ktime_to_ns(ktime_sub(ktime_get(), |
1423 | transaction->t_start_time)); |
1424 | |
1425 | commit_time = min_t(u64, commit_time, |
1426 | 1000*jiffies_to_usecs(1)); |
1427 | |
1428 | if (trans_time < commit_time) { |
1429 | ktime_t expires = ktime_add_ns(ktime_get(), |
1430 | commit_time); |
1431 | set_current_state(TASK_UNINTERRUPTIBLE); |
1432 | schedule_hrtimeout(&expires, HRTIMER_MODE_ABS); |
1433 | } |
1434 | } |
1435 | |
1436 | if (handle->h_sync) |
1437 | transaction->t_synchronous_commit = 1; |
1438 | current->journal_info = NULL; |
1439 | spin_lock(&journal->j_state_lock); |
1440 | spin_lock(&transaction->t_handle_lock); |
1441 | transaction->t_outstanding_credits -= handle->h_buffer_credits; |
1442 | transaction->t_updates--; |
1443 | if (!transaction->t_updates) { |
1444 | wake_up(&journal->j_wait_updates); |
1445 | if (journal->j_barrier_count) |
1446 | 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 | 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 | tid_t tid = transaction->t_tid; |
1463 | |
1464 | 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 | __log_start_commit(journal, transaction->t_tid); |
1469 | 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 | if (handle->h_sync && !(current->flags & PF_MEMALLOC)) |
1476 | err = log_wait_commit(journal, tid); |
1477 | } else { |
1478 | spin_unlock(&transaction->t_handle_lock); |
1479 | spin_unlock(&journal->j_state_lock); |
1480 | } |
1481 | |
1482 | lock_map_release(&handle->h_lockdep_map); |
1483 | |
1484 | jbd_free_handle(handle); |
1485 | 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 | handle_t *handle; |
1499 | int ret; |
1500 | |
1501 | handle = journal_start(journal, 1); |
1502 | if (IS_ERR(handle)) { |
1503 | ret = PTR_ERR(handle); |
1504 | } else { |
1505 | handle->h_sync = 1; |
1506 | ret = journal_stop(handle); |
1507 | } |
1508 | 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 | if (!*list) { |
1531 | jh->b_tnext = jh->b_tprev = jh; |
1532 | *list = jh; |
1533 | } else { |
1534 | /* Insert at the tail of the list to preserve order */ |
1535 | struct journal_head *first = *list, *last = first->b_tprev; |
1536 | jh->b_tprev = last; |
1537 | jh->b_tnext = first; |
1538 | last->b_tnext = first->b_tprev = jh; |
1539 | } |
1540 | } |
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 | if (*list == jh) { |
1555 | *list = jh->b_tnext; |
1556 | if (*list == jh) |
1557 | *list = NULL; |
1558 | } |
1559 | jh->b_tprev->b_tnext = jh->b_tnext; |
1560 | jh->b_tnext->b_tprev = jh->b_tprev; |
1561 | } |
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 | struct journal_head **list = NULL; |
1577 | transaction_t *transaction; |
1578 | struct buffer_head *bh = jh2bh(jh); |
1579 | |
1580 | J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); |
1581 | transaction = jh->b_transaction; |
1582 | if (transaction) |
1583 | assert_spin_locked(&transaction->t_journal->j_list_lock); |
1584 | |
1585 | J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); |
1586 | if (jh->b_jlist != BJ_None) |
1587 | J_ASSERT_JH(jh, transaction != NULL); |
1588 | |
1589 | switch (jh->b_jlist) { |
1590 | case BJ_None: |
1591 | return; |
1592 | case BJ_SyncData: |
1593 | list = &transaction->t_sync_datalist; |
1594 | break; |
1595 | case BJ_Metadata: |
1596 | transaction->t_nr_buffers--; |
1597 | J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0); |
1598 | list = &transaction->t_buffers; |
1599 | break; |
1600 | case BJ_Forget: |
1601 | list = &transaction->t_forget; |
1602 | break; |
1603 | case BJ_IO: |
1604 | list = &transaction->t_iobuf_list; |
1605 | break; |
1606 | case BJ_Shadow: |
1607 | list = &transaction->t_shadow_list; |
1608 | break; |
1609 | case BJ_LogCtl: |
1610 | list = &transaction->t_log_list; |
1611 | break; |
1612 | case BJ_Reserved: |
1613 | list = &transaction->t_reserved_list; |
1614 | break; |
1615 | case BJ_Locked: |
1616 | list = &transaction->t_locked_list; |
1617 | break; |
1618 | } |
1619 | |
1620 | __blist_del_buffer(list, jh); |
1621 | jh->b_jlist = BJ_None; |
1622 | if (test_clear_buffer_jbddirty(bh)) |
1623 | mark_buffer_dirty(bh); /* Expose it to the VM */ |
1624 | } |
1625 | |
1626 | void __journal_unfile_buffer(struct journal_head *jh) |
1627 | { |
1628 | __journal_temp_unlink_buffer(jh); |
1629 | jh->b_transaction = NULL; |
1630 | } |
1631 | |
1632 | void journal_unfile_buffer(journal_t *journal, struct journal_head *jh) |
1633 | { |
1634 | jbd_lock_bh_state(jh2bh(jh)); |
1635 | spin_lock(&journal->j_list_lock); |
1636 | __journal_unfile_buffer(jh); |
1637 | spin_unlock(&journal->j_list_lock); |
1638 | jbd_unlock_bh_state(jh2bh(jh)); |
1639 | } |
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 | struct journal_head *jh; |
1650 | |
1651 | jh = bh2jh(bh); |
1652 | |
1653 | if (buffer_locked(bh) || buffer_dirty(bh)) |
1654 | goto out; |
1655 | |
1656 | if (jh->b_next_transaction != NULL) |
1657 | goto out; |
1658 | |
1659 | spin_lock(&journal->j_list_lock); |
1660 | if (jh->b_transaction != NULL && jh->b_cp_transaction == NULL) { |
1661 | 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 | __journal_unfile_buffer(jh); |
1665 | journal_remove_journal_head(bh); |
1666 | __brelse(bh); |
1667 | } |
1668 | } else if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) { |
1669 | /* written-back checkpointed metadata buffer */ |
1670 | if (jh->b_jlist == BJ_None) { |
1671 | JBUFFER_TRACE(jh, "remove from checkpoint list"); |
1672 | __journal_remove_checkpoint(jh); |
1673 | journal_remove_journal_head(bh); |
1674 | __brelse(bh); |
1675 | } |
1676 | } |
1677 | spin_unlock(&journal->j_list_lock); |
1678 | out: |
1679 | 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 | { |
1723 | struct buffer_head *head; |
1724 | struct buffer_head *bh; |
1725 | int ret = 0; |
1726 | |
1727 | J_ASSERT(PageLocked(page)); |
1728 | |
1729 | head = page_buffers(page); |
1730 | bh = head; |
1731 | 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 | jh = journal_grab_journal_head(bh); |
1740 | if (!jh) |
1741 | continue; |
1742 | |
1743 | jbd_lock_bh_state(bh); |
1744 | __journal_try_to_free_buffer(journal, bh); |
1745 | journal_put_journal_head(jh); |
1746 | jbd_unlock_bh_state(bh); |
1747 | if (buffer_jbd(bh)) |
1748 | goto busy; |
1749 | } while ((bh = bh->b_this_page) != head); |
1750 | |
1751 | ret = try_to_free_buffers(page); |
1752 | |
1753 | busy: |
1754 | 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 | int may_free = 1; |
1772 | struct buffer_head *bh = jh2bh(jh); |
1773 | |
1774 | __journal_unfile_buffer(jh); |
1775 | |
1776 | 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 | clear_buffer_dirty(bh); |
1784 | __journal_file_buffer(jh, transaction, BJ_Forget); |
1785 | may_free = 0; |
1786 | } else { |
1787 | JBUFFER_TRACE(jh, "on running transaction"); |
1788 | journal_remove_journal_head(bh); |
1789 | __brelse(bh); |
1790 | } |
1791 | 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 | transaction_t *transaction; |
1844 | struct journal_head *jh; |
1845 | int may_free = 1; |
1846 | int ret; |
1847 | |
1848 | BUFFER_TRACE(bh, "entry"); |
1849 | |
1850 | /* |
1851 | * It is safe to proceed here without the j_list_lock because the |
1852 | * buffers cannot be stolen by try_to_free_buffers as long as we are |
1853 | * holding the page lock. --sct |
1854 | */ |
1855 | |
1856 | if (!buffer_jbd(bh)) |
1857 | goto zap_buffer_unlocked; |
1858 | |
1859 | spin_lock(&journal->j_state_lock); |
1860 | jbd_lock_bh_state(bh); |
1861 | spin_lock(&journal->j_list_lock); |
1862 | |
1863 | jh = journal_grab_journal_head(bh); |
1864 | if (!jh) |
1865 | goto zap_buffer_no_jh; |
1866 | |
1867 | /* |
1868 | * We cannot remove the buffer from checkpoint lists until the |
1869 | * transaction adding inode to orphan list (let's call it T) |
1870 | * is committed. Otherwise if the transaction changing the |
1871 | * buffer would be cleaned from the journal before T is |
1872 | * committed, a crash will cause that the correct contents of |
1873 | * the buffer will be lost. On the other hand we have to |
1874 | * clear the buffer dirty bit at latest at the moment when the |
1875 | * transaction marking the buffer as freed in the filesystem |
1876 | * structures is committed because from that moment on the |
1877 | * buffer can be reallocated and used by a different page. |
1878 | * Since the block hasn't been freed yet but the inode has |
1879 | * already been added to orphan list, it is safe for us to add |
1880 | * the buffer to BJ_Forget list of the newest transaction. |
1881 | */ |
1882 | transaction = jh->b_transaction; |
1883 | if (transaction == NULL) { |
1884 | /* First case: not on any transaction. If it |
1885 | * has no checkpoint link, then we can zap it: |
1886 | * it's a writeback-mode buffer so we don't care |
1887 | * if it hits disk safely. */ |
1888 | if (!jh->b_cp_transaction) { |
1889 | JBUFFER_TRACE(jh, "not on any transaction: zap"); |
1890 | goto zap_buffer; |
1891 | } |
1892 | |
1893 | if (!buffer_dirty(bh)) { |
1894 | /* bdflush has written it. We can drop it now */ |
1895 | goto zap_buffer; |
1896 | } |
1897 | |
1898 | /* OK, it must be in the journal but still not |
1899 | * written fully to disk: it's metadata or |
1900 | * journaled data... */ |
1901 | |
1902 | if (journal->j_running_transaction) { |
1903 | /* ... and once the current transaction has |
1904 | * committed, the buffer won't be needed any |
1905 | * longer. */ |
1906 | JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget"); |
1907 | ret = __dispose_buffer(jh, |
1908 | journal->j_running_transaction); |
1909 | journal_put_journal_head(jh); |
1910 | spin_unlock(&journal->j_list_lock); |
1911 | jbd_unlock_bh_state(bh); |
1912 | spin_unlock(&journal->j_state_lock); |
1913 | return ret; |
1914 | } else { |
1915 | /* There is no currently-running transaction. So the |
1916 | * orphan record which we wrote for this file must have |
1917 | * passed into commit. We must attach this buffer to |
1918 | * the committing transaction, if it exists. */ |
1919 | if (journal->j_committing_transaction) { |
1920 | JBUFFER_TRACE(jh, "give to committing trans"); |
1921 | ret = __dispose_buffer(jh, |
1922 | journal->j_committing_transaction); |
1923 | journal_put_journal_head(jh); |
1924 | spin_unlock(&journal->j_list_lock); |
1925 | jbd_unlock_bh_state(bh); |
1926 | spin_unlock(&journal->j_state_lock); |
1927 | return ret; |
1928 | } else { |
1929 | /* The orphan record's transaction has |
1930 | * committed. We can cleanse this buffer */ |
1931 | clear_buffer_jbddirty(bh); |
1932 | goto zap_buffer; |
1933 | } |
1934 | } |
1935 | } else if (transaction == journal->j_committing_transaction) { |
1936 | JBUFFER_TRACE(jh, "on committing transaction"); |
1937 | if (jh->b_jlist == BJ_Locked) { |
1938 | /* |
1939 | * The buffer is on the committing transaction's locked |
1940 | * list. We have the buffer locked, so I/O has |
1941 | * completed. So we can nail the buffer now. |
1942 | */ |
1943 | may_free = __dispose_buffer(jh, transaction); |
1944 | goto zap_buffer; |
1945 | } |
1946 | /* |
1947 | * The buffer is committing, we simply cannot touch |
1948 | * it. So we just set j_next_transaction to the |
1949 | * running transaction (if there is one) and mark |
1950 | * buffer as freed so that commit code knows it should |
1951 | * clear dirty bits when it is done with the buffer. |
1952 | */ |
1953 | set_buffer_freed(bh); |
1954 | if (journal->j_running_transaction && buffer_jbddirty(bh)) |
1955 | jh->b_next_transaction = journal->j_running_transaction; |
1956 | journal_put_journal_head(jh); |
1957 | spin_unlock(&journal->j_list_lock); |
1958 | jbd_unlock_bh_state(bh); |
1959 | spin_unlock(&journal->j_state_lock); |
1960 | return 0; |
1961 | } else { |
1962 | /* Good, the buffer belongs to the running transaction. |
1963 | * We are writing our own transaction's data, not any |
1964 | * previous one's, so it is safe to throw it away |
1965 | * (remember that we expect the filesystem to have set |
1966 | * i_size already for this truncate so recovery will not |
1967 | * expose the disk blocks we are discarding here.) */ |
1968 | J_ASSERT_JH(jh, transaction == journal->j_running_transaction); |
1969 | JBUFFER_TRACE(jh, "on running transaction"); |
1970 | may_free = __dispose_buffer(jh, transaction); |
1971 | } |
1972 | |
1973 | zap_buffer: |
1974 | journal_put_journal_head(jh); |
1975 | zap_buffer_no_jh: |
1976 | spin_unlock(&journal->j_list_lock); |
1977 | jbd_unlock_bh_state(bh); |
1978 | spin_unlock(&journal->j_state_lock); |
1979 | zap_buffer_unlocked: |
1980 | clear_buffer_dirty(bh); |
1981 | J_ASSERT_BH(bh, !buffer_jbddirty(bh)); |
1982 | clear_buffer_mapped(bh); |
1983 | clear_buffer_req(bh); |
1984 | clear_buffer_new(bh); |
1985 | bh->b_bdev = NULL; |
1986 | return may_free; |
1987 | } |
1988 | |
1989 | /** |
1990 | * void journal_invalidatepage() - invalidate a journal page |
1991 | * @journal: journal to use for flush |
1992 | * @page: page to flush |
1993 | * @offset: length of page to invalidate. |
1994 | * |
1995 | * Reap page buffers containing data after offset in page. |
1996 | */ |
1997 | void journal_invalidatepage(journal_t *journal, |
1998 | struct page *page, |
1999 | unsigned long offset) |
2000 | { |
2001 | struct buffer_head *head, *bh, *next; |
2002 | unsigned int curr_off = 0; |
2003 | int may_free = 1; |
2004 | |
2005 | if (!PageLocked(page)) |
2006 | BUG(); |
2007 | if (!page_has_buffers(page)) |
2008 | return; |
2009 | |
2010 | /* We will potentially be playing with lists other than just the |
2011 | * data lists (especially for journaled data mode), so be |
2012 | * cautious in our locking. */ |
2013 | |
2014 | head = bh = page_buffers(page); |
2015 | do { |
2016 | unsigned int next_off = curr_off + bh->b_size; |
2017 | next = bh->b_this_page; |
2018 | |
2019 | if (offset <= curr_off) { |
2020 | /* This block is wholly outside the truncation point */ |
2021 | lock_buffer(bh); |
2022 | may_free &= journal_unmap_buffer(journal, bh); |
2023 | unlock_buffer(bh); |
2024 | } |
2025 | curr_off = next_off; |
2026 | bh = next; |
2027 | |
2028 | } while (bh != head); |
2029 | |
2030 | if (!offset) { |
2031 | if (may_free && try_to_free_buffers(page)) |
2032 | J_ASSERT(!page_has_buffers(page)); |
2033 | } |
2034 | } |
2035 | |
2036 | /* |
2037 | * File a buffer on the given transaction list. |
2038 | */ |
2039 | void __journal_file_buffer(struct journal_head *jh, |
2040 | transaction_t *transaction, int jlist) |
2041 | { |
2042 | struct journal_head **list = NULL; |
2043 | int was_dirty = 0; |
2044 | struct buffer_head *bh = jh2bh(jh); |
2045 | |
2046 | J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); |
2047 | assert_spin_locked(&transaction->t_journal->j_list_lock); |
2048 | |
2049 | J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); |
2050 | J_ASSERT_JH(jh, jh->b_transaction == transaction || |
2051 | jh->b_transaction == NULL); |
2052 | |
2053 | if (jh->b_transaction && jh->b_jlist == jlist) |
2054 | return; |
2055 | |
2056 | if (jlist == BJ_Metadata || jlist == BJ_Reserved || |
2057 | jlist == BJ_Shadow || jlist == BJ_Forget) { |
2058 | /* |
2059 | * For metadata buffers, we track dirty bit in buffer_jbddirty |
2060 | * instead of buffer_dirty. We should not see a dirty bit set |
2061 | * here because we clear it in do_get_write_access but e.g. |
2062 | * tune2fs can modify the sb and set the dirty bit at any time |
2063 | * so we try to gracefully handle that. |
2064 | */ |
2065 | if (buffer_dirty(bh)) |
2066 | warn_dirty_buffer(bh); |
2067 | if (test_clear_buffer_dirty(bh) || |
2068 | test_clear_buffer_jbddirty(bh)) |
2069 | was_dirty = 1; |
2070 | } |
2071 | |
2072 | if (jh->b_transaction) |
2073 | __journal_temp_unlink_buffer(jh); |
2074 | jh->b_transaction = transaction; |
2075 | |
2076 | switch (jlist) { |
2077 | case BJ_None: |
2078 | J_ASSERT_JH(jh, !jh->b_committed_data); |
2079 | J_ASSERT_JH(jh, !jh->b_frozen_data); |
2080 | return; |
2081 | case BJ_SyncData: |
2082 | list = &transaction->t_sync_datalist; |
2083 | break; |
2084 | case BJ_Metadata: |
2085 | transaction->t_nr_buffers++; |
2086 | list = &transaction->t_buffers; |
2087 | break; |
2088 | case BJ_Forget: |
2089 | list = &transaction->t_forget; |
2090 | break; |
2091 | case BJ_IO: |
2092 | list = &transaction->t_iobuf_list; |
2093 | break; |
2094 | case BJ_Shadow: |
2095 | list = &transaction->t_shadow_list; |
2096 | break; |
2097 | case BJ_LogCtl: |
2098 | list = &transaction->t_log_list; |
2099 | break; |
2100 | case BJ_Reserved: |
2101 | list = &transaction->t_reserved_list; |
2102 | break; |
2103 | case BJ_Locked: |
2104 | list = &transaction->t_locked_list; |
2105 | break; |
2106 | } |
2107 | |
2108 | __blist_add_buffer(list, jh); |
2109 | jh->b_jlist = jlist; |
2110 | |
2111 | if (was_dirty) |
2112 | set_buffer_jbddirty(bh); |
2113 | } |
2114 | |
2115 | void journal_file_buffer(struct journal_head *jh, |
2116 | transaction_t *transaction, int jlist) |
2117 | { |
2118 | jbd_lock_bh_state(jh2bh(jh)); |
2119 | spin_lock(&transaction->t_journal->j_list_lock); |
2120 | __journal_file_buffer(jh, transaction, jlist); |
2121 | spin_unlock(&transaction->t_journal->j_list_lock); |
2122 | jbd_unlock_bh_state(jh2bh(jh)); |
2123 | } |
2124 | |
2125 | /* |
2126 | * Remove a buffer from its current buffer list in preparation for |
2127 | * dropping it from its current transaction entirely. If the buffer has |
2128 | * already started to be used by a subsequent transaction, refile the |
2129 | * buffer on that transaction's metadata list. |
2130 | * |
2131 | * Called under journal->j_list_lock |
2132 | * |
2133 | * Called under jbd_lock_bh_state(jh2bh(jh)) |
2134 | */ |
2135 | void __journal_refile_buffer(struct journal_head *jh) |
2136 | { |
2137 | int was_dirty, jlist; |
2138 | struct buffer_head *bh = jh2bh(jh); |
2139 | |
2140 | J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); |
2141 | if (jh->b_transaction) |
2142 | assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock); |
2143 | |
2144 | /* If the buffer is now unused, just drop it. */ |
2145 | if (jh->b_next_transaction == NULL) { |
2146 | __journal_unfile_buffer(jh); |
2147 | return; |
2148 | } |
2149 | |
2150 | /* |
2151 | * It has been modified by a later transaction: add it to the new |
2152 | * transaction's metadata list. |
2153 | */ |
2154 | |
2155 | was_dirty = test_clear_buffer_jbddirty(bh); |
2156 | __journal_temp_unlink_buffer(jh); |
2157 | jh->b_transaction = jh->b_next_transaction; |
2158 | jh->b_next_transaction = NULL; |
2159 | if (buffer_freed(bh)) |
2160 | jlist = BJ_Forget; |
2161 | else if (jh->b_modified) |
2162 | jlist = BJ_Metadata; |
2163 | else |
2164 | jlist = BJ_Reserved; |
2165 | __journal_file_buffer(jh, jh->b_transaction, jlist); |
2166 | J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING); |
2167 | |
2168 | if (was_dirty) |
2169 | set_buffer_jbddirty(bh); |
2170 | } |
2171 | |
2172 | /* |
2173 | * For the unlocked version of this call, also make sure that any |
2174 | * hanging journal_head is cleaned up if necessary. |
2175 | * |
2176 | * __journal_refile_buffer is usually called as part of a single locked |
2177 | * operation on a buffer_head, in which the caller is probably going to |
2178 | * be hooking the journal_head onto other lists. In that case it is up |
2179 | * to the caller to remove the journal_head if necessary. For the |
2180 | * unlocked journal_refile_buffer call, the caller isn't going to be |
2181 | * doing anything else to the buffer so we need to do the cleanup |
2182 | * ourselves to avoid a jh leak. |
2183 | * |
2184 | * *** The journal_head may be freed by this call! *** |
2185 | */ |
2186 | void journal_refile_buffer(journal_t *journal, struct journal_head *jh) |
2187 | { |
2188 | struct buffer_head *bh = jh2bh(jh); |
2189 | |
2190 | jbd_lock_bh_state(bh); |
2191 | spin_lock(&journal->j_list_lock); |
2192 | |
2193 | __journal_refile_buffer(jh); |
2194 | jbd_unlock_bh_state(bh); |
2195 | journal_remove_journal_head(bh); |
2196 | |
2197 | spin_unlock(&journal->j_list_lock); |
2198 | __brelse(bh); |
2199 | } |
2200 |
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