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1da177e4 | 1 | /* |
58862699 | 2 | * linux/fs/jbd/transaction.c |
ae6ddcc5 | 3 | * |
1da177e4 LT |
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 | |
ae6ddcc5 | 13 | * journaling system. |
1da177e4 LT |
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> | |
1da177e4 LT |
26 | #include <linux/mm.h> |
27 | #include <linux/highmem.h> | |
28 | ||
d394e122 AB |
29 | static void __journal_temp_unlink_buffer(struct journal_head *jh); |
30 | ||
1da177e4 LT |
31 | /* |
32 | * get_transaction: obtain a new transaction_t object. | |
33 | * | |
34 | * Simply allocate and initialise a new transaction. Create it in | |
35 | * RUNNING state and add it to the current journal (which should not | |
36 | * have an existing running transaction: we only make a new transaction | |
37 | * once we have started to commit the old one). | |
38 | * | |
39 | * Preconditions: | |
40 | * The journal MUST be locked. We don't perform atomic mallocs on the | |
41 | * new transaction and we can't block without protecting against other | |
42 | * processes trying to touch the journal while it is in transition. | |
43 | * | |
44 | * Called under j_state_lock | |
45 | */ | |
46 | ||
47 | static transaction_t * | |
48 | get_transaction(journal_t *journal, transaction_t *transaction) | |
49 | { | |
50 | transaction->t_journal = journal; | |
51 | transaction->t_state = T_RUNNING; | |
52 | transaction->t_tid = journal->j_transaction_sequence++; | |
53 | transaction->t_expires = jiffies + journal->j_commit_interval; | |
54 | spin_lock_init(&transaction->t_handle_lock); | |
55 | ||
56 | /* Set up the commit timer for the new transaction. */ | |
44d306e1 | 57 | journal->j_commit_timer.expires = round_jiffies(transaction->t_expires); |
e3df1898 | 58 | add_timer(&journal->j_commit_timer); |
1da177e4 LT |
59 | |
60 | J_ASSERT(journal->j_running_transaction == NULL); | |
61 | journal->j_running_transaction = transaction; | |
62 | ||
63 | return transaction; | |
64 | } | |
65 | ||
66 | /* | |
67 | * Handle management. | |
68 | * | |
69 | * A handle_t is an object which represents a single atomic update to a | |
70 | * filesystem, and which tracks all of the modifications which form part | |
71 | * of that one update. | |
72 | */ | |
73 | ||
74 | /* | |
75 | * start_this_handle: Given a handle, deal with any locking or stalling | |
76 | * needed to make sure that there is enough journal space for the handle | |
77 | * to begin. Attach the handle to a transaction and set up the | |
ae6ddcc5 | 78 | * transaction's buffer credits. |
1da177e4 LT |
79 | */ |
80 | ||
81 | static int start_this_handle(journal_t *journal, handle_t *handle) | |
82 | { | |
83 | transaction_t *transaction; | |
84 | int needed; | |
85 | int nblocks = handle->h_buffer_credits; | |
86 | transaction_t *new_transaction = NULL; | |
87 | int ret = 0; | |
88 | ||
89 | if (nblocks > journal->j_max_transaction_buffers) { | |
90 | printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n", | |
91 | current->comm, nblocks, | |
92 | journal->j_max_transaction_buffers); | |
93 | ret = -ENOSPC; | |
94 | goto out; | |
95 | } | |
96 | ||
97 | alloc_transaction: | |
98 | if (!journal->j_running_transaction) { | |
99 | new_transaction = jbd_kmalloc(sizeof(*new_transaction), | |
100 | GFP_NOFS); | |
101 | if (!new_transaction) { | |
102 | ret = -ENOMEM; | |
103 | goto out; | |
104 | } | |
105 | memset(new_transaction, 0, sizeof(*new_transaction)); | |
106 | } | |
107 | ||
108 | jbd_debug(3, "New handle %p going live.\n", handle); | |
109 | ||
110 | repeat: | |
111 | ||
112 | /* | |
113 | * We need to hold j_state_lock until t_updates has been incremented, | |
114 | * for proper journal barrier handling | |
115 | */ | |
116 | spin_lock(&journal->j_state_lock); | |
117 | repeat_locked: | |
118 | if (is_journal_aborted(journal) || | |
119 | (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) { | |
120 | spin_unlock(&journal->j_state_lock); | |
ae6ddcc5 | 121 | ret = -EROFS; |
1da177e4 LT |
122 | goto out; |
123 | } | |
124 | ||
125 | /* Wait on the journal's transaction barrier if necessary */ | |
126 | if (journal->j_barrier_count) { | |
127 | spin_unlock(&journal->j_state_lock); | |
128 | wait_event(journal->j_wait_transaction_locked, | |
129 | journal->j_barrier_count == 0); | |
130 | goto repeat; | |
131 | } | |
132 | ||
133 | if (!journal->j_running_transaction) { | |
134 | if (!new_transaction) { | |
135 | spin_unlock(&journal->j_state_lock); | |
136 | goto alloc_transaction; | |
137 | } | |
138 | get_transaction(journal, new_transaction); | |
139 | new_transaction = NULL; | |
140 | } | |
141 | ||
142 | transaction = journal->j_running_transaction; | |
143 | ||
144 | /* | |
145 | * If the current transaction is locked down for commit, wait for the | |
146 | * lock to be released. | |
147 | */ | |
148 | if (transaction->t_state == T_LOCKED) { | |
149 | DEFINE_WAIT(wait); | |
150 | ||
151 | prepare_to_wait(&journal->j_wait_transaction_locked, | |
152 | &wait, TASK_UNINTERRUPTIBLE); | |
153 | spin_unlock(&journal->j_state_lock); | |
154 | schedule(); | |
155 | finish_wait(&journal->j_wait_transaction_locked, &wait); | |
156 | goto repeat; | |
157 | } | |
158 | ||
159 | /* | |
160 | * If there is not enough space left in the log to write all potential | |
161 | * buffers requested by this operation, we need to stall pending a log | |
162 | * checkpoint to free some more log space. | |
163 | */ | |
164 | spin_lock(&transaction->t_handle_lock); | |
165 | needed = transaction->t_outstanding_credits + nblocks; | |
166 | ||
167 | if (needed > journal->j_max_transaction_buffers) { | |
168 | /* | |
169 | * If the current transaction is already too large, then start | |
170 | * to commit it: we can then go back and attach this handle to | |
171 | * a new transaction. | |
172 | */ | |
173 | DEFINE_WAIT(wait); | |
174 | ||
175 | jbd_debug(2, "Handle %p starting new commit...\n", handle); | |
176 | spin_unlock(&transaction->t_handle_lock); | |
177 | prepare_to_wait(&journal->j_wait_transaction_locked, &wait, | |
178 | TASK_UNINTERRUPTIBLE); | |
179 | __log_start_commit(journal, transaction->t_tid); | |
180 | spin_unlock(&journal->j_state_lock); | |
181 | schedule(); | |
182 | finish_wait(&journal->j_wait_transaction_locked, &wait); | |
183 | goto repeat; | |
184 | } | |
185 | ||
ae6ddcc5 | 186 | /* |
1da177e4 LT |
187 | * The commit code assumes that it can get enough log space |
188 | * without forcing a checkpoint. This is *critical* for | |
189 | * correctness: a checkpoint of a buffer which is also | |
190 | * associated with a committing transaction creates a deadlock, | |
191 | * so commit simply cannot force through checkpoints. | |
192 | * | |
193 | * We must therefore ensure the necessary space in the journal | |
194 | * *before* starting to dirty potentially checkpointed buffers | |
ae6ddcc5 | 195 | * in the new transaction. |
1da177e4 LT |
196 | * |
197 | * The worst part is, any transaction currently committing can | |
198 | * reduce the free space arbitrarily. Be careful to account for | |
199 | * those buffers when checkpointing. | |
200 | */ | |
201 | ||
202 | /* | |
203 | * @@@ AKPM: This seems rather over-defensive. We're giving commit | |
204 | * a _lot_ of headroom: 1/4 of the journal plus the size of | |
205 | * the committing transaction. Really, we only need to give it | |
206 | * committing_transaction->t_outstanding_credits plus "enough" for | |
207 | * the log control blocks. | |
208 | * Also, this test is inconsitent with the matching one in | |
209 | * journal_extend(). | |
210 | */ | |
211 | if (__log_space_left(journal) < jbd_space_needed(journal)) { | |
212 | jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle); | |
213 | spin_unlock(&transaction->t_handle_lock); | |
214 | __log_wait_for_space(journal); | |
215 | goto repeat_locked; | |
216 | } | |
217 | ||
218 | /* OK, account for the buffers that this operation expects to | |
219 | * use and add the handle to the running transaction. */ | |
220 | ||
221 | handle->h_transaction = transaction; | |
222 | transaction->t_outstanding_credits += nblocks; | |
223 | transaction->t_updates++; | |
224 | transaction->t_handle_count++; | |
225 | jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n", | |
226 | handle, nblocks, transaction->t_outstanding_credits, | |
227 | __log_space_left(journal)); | |
228 | spin_unlock(&transaction->t_handle_lock); | |
229 | spin_unlock(&journal->j_state_lock); | |
230 | out: | |
304c4c84 AM |
231 | if (unlikely(new_transaction)) /* It's usually NULL */ |
232 | kfree(new_transaction); | |
1da177e4 LT |
233 | return ret; |
234 | } | |
235 | ||
34a3d1e8 PZ |
236 | static struct lock_class_key jbd_handle_key; |
237 | ||
1da177e4 LT |
238 | /* Allocate a new handle. This should probably be in a slab... */ |
239 | static handle_t *new_handle(int nblocks) | |
240 | { | |
241 | handle_t *handle = jbd_alloc_handle(GFP_NOFS); | |
242 | if (!handle) | |
243 | return NULL; | |
244 | memset(handle, 0, sizeof(*handle)); | |
245 | handle->h_buffer_credits = nblocks; | |
246 | handle->h_ref = 1; | |
247 | ||
34a3d1e8 PZ |
248 | lockdep_init_map(&handle->h_lockdep_map, "jbd_handle", &jbd_handle_key, 0); |
249 | ||
1da177e4 LT |
250 | return handle; |
251 | } | |
252 | ||
253 | /** | |
ae6ddcc5 | 254 | * handle_t *journal_start() - Obtain a new handle. |
1da177e4 LT |
255 | * @journal: Journal to start transaction on. |
256 | * @nblocks: number of block buffer we might modify | |
257 | * | |
258 | * We make sure that the transaction can guarantee at least nblocks of | |
259 | * modified buffers in the log. We block until the log can guarantee | |
ae6ddcc5 | 260 | * that much space. |
1da177e4 LT |
261 | * |
262 | * This function is visible to journal users (like ext3fs), so is not | |
263 | * called with the journal already locked. | |
264 | * | |
265 | * Return a pointer to a newly allocated handle, or NULL on failure | |
266 | */ | |
267 | handle_t *journal_start(journal_t *journal, int nblocks) | |
268 | { | |
269 | handle_t *handle = journal_current_handle(); | |
270 | int err; | |
271 | ||
272 | if (!journal) | |
273 | return ERR_PTR(-EROFS); | |
274 | ||
275 | if (handle) { | |
276 | J_ASSERT(handle->h_transaction->t_journal == journal); | |
277 | handle->h_ref++; | |
278 | return handle; | |
279 | } | |
280 | ||
281 | handle = new_handle(nblocks); | |
282 | if (!handle) | |
283 | return ERR_PTR(-ENOMEM); | |
284 | ||
285 | current->journal_info = handle; | |
286 | ||
287 | err = start_this_handle(journal, handle); | |
288 | if (err < 0) { | |
289 | jbd_free_handle(handle); | |
290 | current->journal_info = NULL; | |
291 | handle = ERR_PTR(err); | |
292 | } | |
34a3d1e8 PZ |
293 | |
294 | lock_acquire(&handle->h_lockdep_map, 0, 0, 0, 2, _THIS_IP_); | |
295 | ||
1da177e4 LT |
296 | return handle; |
297 | } | |
298 | ||
299 | /** | |
300 | * int journal_extend() - extend buffer credits. | |
301 | * @handle: handle to 'extend' | |
302 | * @nblocks: nr blocks to try to extend by. | |
ae6ddcc5 | 303 | * |
1da177e4 LT |
304 | * Some transactions, such as large extends and truncates, can be done |
305 | * atomically all at once or in several stages. The operation requests | |
306 | * a credit for a number of buffer modications in advance, but can | |
ae6ddcc5 | 307 | * extend its credit if it needs more. |
1da177e4 LT |
308 | * |
309 | * journal_extend tries to give the running handle more buffer credits. | |
310 | * It does not guarantee that allocation - this is a best-effort only. | |
311 | * The calling process MUST be able to deal cleanly with a failure to | |
312 | * extend here. | |
313 | * | |
314 | * Return 0 on success, non-zero on failure. | |
315 | * | |
316 | * return code < 0 implies an error | |
317 | * return code > 0 implies normal transaction-full status. | |
318 | */ | |
319 | int journal_extend(handle_t *handle, int nblocks) | |
320 | { | |
321 | transaction_t *transaction = handle->h_transaction; | |
322 | journal_t *journal = transaction->t_journal; | |
323 | int result; | |
324 | int wanted; | |
325 | ||
326 | result = -EIO; | |
327 | if (is_handle_aborted(handle)) | |
328 | goto out; | |
329 | ||
330 | result = 1; | |
331 | ||
332 | spin_lock(&journal->j_state_lock); | |
333 | ||
334 | /* Don't extend a locked-down transaction! */ | |
335 | if (handle->h_transaction->t_state != T_RUNNING) { | |
336 | jbd_debug(3, "denied handle %p %d blocks: " | |
337 | "transaction not running\n", handle, nblocks); | |
338 | goto error_out; | |
339 | } | |
340 | ||
341 | spin_lock(&transaction->t_handle_lock); | |
342 | wanted = transaction->t_outstanding_credits + nblocks; | |
343 | ||
344 | if (wanted > journal->j_max_transaction_buffers) { | |
345 | jbd_debug(3, "denied handle %p %d blocks: " | |
346 | "transaction too large\n", handle, nblocks); | |
347 | goto unlock; | |
348 | } | |
349 | ||
350 | if (wanted > __log_space_left(journal)) { | |
351 | jbd_debug(3, "denied handle %p %d blocks: " | |
352 | "insufficient log space\n", handle, nblocks); | |
353 | goto unlock; | |
354 | } | |
355 | ||
356 | handle->h_buffer_credits += nblocks; | |
357 | transaction->t_outstanding_credits += nblocks; | |
358 | result = 0; | |
359 | ||
360 | jbd_debug(3, "extended handle %p by %d\n", handle, nblocks); | |
361 | unlock: | |
362 | spin_unlock(&transaction->t_handle_lock); | |
363 | error_out: | |
364 | spin_unlock(&journal->j_state_lock); | |
365 | out: | |
366 | return result; | |
367 | } | |
368 | ||
369 | ||
370 | /** | |
371 | * int journal_restart() - restart a handle . | |
372 | * @handle: handle to restart | |
373 | * @nblocks: nr credits requested | |
ae6ddcc5 | 374 | * |
1da177e4 LT |
375 | * Restart a handle for a multi-transaction filesystem |
376 | * operation. | |
377 | * | |
378 | * If the journal_extend() call above fails to grant new buffer credits | |
379 | * to a running handle, a call to journal_restart will commit the | |
380 | * handle's transaction so far and reattach the handle to a new | |
381 | * transaction capabable of guaranteeing the requested number of | |
382 | * credits. | |
383 | */ | |
384 | ||
385 | int journal_restart(handle_t *handle, int nblocks) | |
386 | { | |
387 | transaction_t *transaction = handle->h_transaction; | |
388 | journal_t *journal = transaction->t_journal; | |
389 | int ret; | |
390 | ||
391 | /* If we've had an abort of any type, don't even think about | |
392 | * actually doing the restart! */ | |
393 | if (is_handle_aborted(handle)) | |
394 | return 0; | |
395 | ||
396 | /* | |
397 | * First unlink the handle from its current transaction, and start the | |
398 | * commit on that. | |
399 | */ | |
400 | J_ASSERT(transaction->t_updates > 0); | |
401 | J_ASSERT(journal_current_handle() == handle); | |
402 | ||
403 | spin_lock(&journal->j_state_lock); | |
404 | spin_lock(&transaction->t_handle_lock); | |
405 | transaction->t_outstanding_credits -= handle->h_buffer_credits; | |
406 | transaction->t_updates--; | |
407 | ||
408 | if (!transaction->t_updates) | |
409 | wake_up(&journal->j_wait_updates); | |
410 | spin_unlock(&transaction->t_handle_lock); | |
411 | ||
412 | jbd_debug(2, "restarting handle %p\n", handle); | |
413 | __log_start_commit(journal, transaction->t_tid); | |
414 | spin_unlock(&journal->j_state_lock); | |
415 | ||
416 | handle->h_buffer_credits = nblocks; | |
417 | ret = start_this_handle(journal, handle); | |
418 | return ret; | |
419 | } | |
420 | ||
421 | ||
422 | /** | |
423 | * void journal_lock_updates () - establish a transaction barrier. | |
424 | * @journal: Journal to establish a barrier on. | |
425 | * | |
426 | * This locks out any further updates from being started, and blocks | |
427 | * until all existing updates have completed, returning only once the | |
428 | * journal is in a quiescent state with no updates running. | |
429 | * | |
430 | * The journal lock should not be held on entry. | |
431 | */ | |
432 | void journal_lock_updates(journal_t *journal) | |
433 | { | |
434 | DEFINE_WAIT(wait); | |
435 | ||
436 | spin_lock(&journal->j_state_lock); | |
437 | ++journal->j_barrier_count; | |
438 | ||
439 | /* Wait until there are no running updates */ | |
440 | while (1) { | |
441 | transaction_t *transaction = journal->j_running_transaction; | |
442 | ||
443 | if (!transaction) | |
444 | break; | |
445 | ||
446 | spin_lock(&transaction->t_handle_lock); | |
447 | if (!transaction->t_updates) { | |
448 | spin_unlock(&transaction->t_handle_lock); | |
449 | break; | |
450 | } | |
451 | prepare_to_wait(&journal->j_wait_updates, &wait, | |
452 | TASK_UNINTERRUPTIBLE); | |
453 | spin_unlock(&transaction->t_handle_lock); | |
454 | spin_unlock(&journal->j_state_lock); | |
455 | schedule(); | |
456 | finish_wait(&journal->j_wait_updates, &wait); | |
457 | spin_lock(&journal->j_state_lock); | |
458 | } | |
459 | spin_unlock(&journal->j_state_lock); | |
460 | ||
461 | /* | |
462 | * We have now established a barrier against other normal updates, but | |
463 | * we also need to barrier against other journal_lock_updates() calls | |
464 | * to make sure that we serialise special journal-locked operations | |
465 | * too. | |
466 | */ | |
2c68ee75 | 467 | mutex_lock(&journal->j_barrier); |
1da177e4 LT |
468 | } |
469 | ||
470 | /** | |
471 | * void journal_unlock_updates (journal_t* journal) - release barrier | |
472 | * @journal: Journal to release the barrier on. | |
ae6ddcc5 | 473 | * |
1da177e4 LT |
474 | * Release a transaction barrier obtained with journal_lock_updates(). |
475 | * | |
476 | * Should be called without the journal lock held. | |
477 | */ | |
478 | void journal_unlock_updates (journal_t *journal) | |
479 | { | |
480 | J_ASSERT(journal->j_barrier_count != 0); | |
481 | ||
2c68ee75 | 482 | mutex_unlock(&journal->j_barrier); |
1da177e4 LT |
483 | spin_lock(&journal->j_state_lock); |
484 | --journal->j_barrier_count; | |
485 | spin_unlock(&journal->j_state_lock); | |
486 | wake_up(&journal->j_wait_transaction_locked); | |
487 | } | |
488 | ||
489 | /* | |
490 | * Report any unexpected dirty buffers which turn up. Normally those | |
491 | * indicate an error, but they can occur if the user is running (say) | |
492 | * tune2fs to modify the live filesystem, so we need the option of | |
493 | * continuing as gracefully as possible. # | |
494 | * | |
495 | * The caller should already hold the journal lock and | |
496 | * j_list_lock spinlock: most callers will need those anyway | |
497 | * in order to probe the buffer's journaling state safely. | |
498 | */ | |
499 | static void jbd_unexpected_dirty_buffer(struct journal_head *jh) | |
500 | { | |
1da177e4 LT |
501 | int jlist; |
502 | ||
4407c2b6 JK |
503 | /* If this buffer is one which might reasonably be dirty |
504 | * --- ie. data, or not part of this journal --- then | |
505 | * we're OK to leave it alone, but otherwise we need to | |
506 | * move the dirty bit to the journal's own internal | |
507 | * JBDDirty bit. */ | |
508 | jlist = jh->b_jlist; | |
509 | ||
510 | if (jlist == BJ_Metadata || jlist == BJ_Reserved || | |
511 | jlist == BJ_Shadow || jlist == BJ_Forget) { | |
512 | struct buffer_head *bh = jh2bh(jh); | |
513 | ||
514 | if (test_clear_buffer_dirty(bh)) | |
515 | set_buffer_jbddirty(bh); | |
1da177e4 LT |
516 | } |
517 | } | |
518 | ||
519 | /* | |
520 | * If the buffer is already part of the current transaction, then there | |
521 | * is nothing we need to do. If it is already part of a prior | |
522 | * transaction which we are still committing to disk, then we need to | |
523 | * make sure that we do not overwrite the old copy: we do copy-out to | |
524 | * preserve the copy going to disk. We also account the buffer against | |
525 | * the handle's metadata buffer credits (unless the buffer is already | |
526 | * part of the transaction, that is). | |
527 | * | |
528 | */ | |
529 | static int | |
530 | do_get_write_access(handle_t *handle, struct journal_head *jh, | |
531 | int force_copy) | |
532 | { | |
533 | struct buffer_head *bh; | |
534 | transaction_t *transaction; | |
535 | journal_t *journal; | |
536 | int error; | |
537 | char *frozen_buffer = NULL; | |
538 | int need_copy = 0; | |
539 | ||
540 | if (is_handle_aborted(handle)) | |
541 | return -EROFS; | |
542 | ||
543 | transaction = handle->h_transaction; | |
544 | journal = transaction->t_journal; | |
545 | ||
546 | jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy); | |
547 | ||
548 | JBUFFER_TRACE(jh, "entry"); | |
549 | repeat: | |
550 | bh = jh2bh(jh); | |
551 | ||
552 | /* @@@ Need to check for errors here at some point. */ | |
553 | ||
554 | lock_buffer(bh); | |
555 | jbd_lock_bh_state(bh); | |
556 | ||
557 | /* We now hold the buffer lock so it is safe to query the buffer | |
ae6ddcc5 MC |
558 | * state. Is the buffer dirty? |
559 | * | |
1da177e4 LT |
560 | * If so, there are two possibilities. The buffer may be |
561 | * non-journaled, and undergoing a quite legitimate writeback. | |
562 | * Otherwise, it is journaled, and we don't expect dirty buffers | |
563 | * in that state (the buffers should be marked JBD_Dirty | |
564 | * instead.) So either the IO is being done under our own | |
565 | * control and this is a bug, or it's a third party IO such as | |
566 | * dump(8) (which may leave the buffer scheduled for read --- | |
567 | * ie. locked but not dirty) or tune2fs (which may actually have | |
568 | * the buffer dirtied, ugh.) */ | |
569 | ||
570 | if (buffer_dirty(bh)) { | |
571 | /* | |
572 | * First question: is this buffer already part of the current | |
573 | * transaction or the existing committing transaction? | |
574 | */ | |
575 | if (jh->b_transaction) { | |
576 | J_ASSERT_JH(jh, | |
ae6ddcc5 | 577 | jh->b_transaction == transaction || |
1da177e4 LT |
578 | jh->b_transaction == |
579 | journal->j_committing_transaction); | |
580 | if (jh->b_next_transaction) | |
581 | J_ASSERT_JH(jh, jh->b_next_transaction == | |
582 | transaction); | |
4407c2b6 JK |
583 | } |
584 | /* | |
585 | * In any case we need to clean the dirty flag and we must | |
586 | * do it under the buffer lock to be sure we don't race | |
587 | * with running write-out. | |
588 | */ | |
589 | JBUFFER_TRACE(jh, "Unexpected dirty buffer"); | |
590 | jbd_unexpected_dirty_buffer(jh); | |
e9ad5620 | 591 | } |
1da177e4 LT |
592 | |
593 | unlock_buffer(bh); | |
594 | ||
595 | error = -EROFS; | |
596 | if (is_handle_aborted(handle)) { | |
597 | jbd_unlock_bh_state(bh); | |
598 | goto out; | |
599 | } | |
600 | error = 0; | |
601 | ||
602 | /* | |
603 | * The buffer is already part of this transaction if b_transaction or | |
604 | * b_next_transaction points to it | |
605 | */ | |
606 | if (jh->b_transaction == transaction || | |
607 | jh->b_next_transaction == transaction) | |
608 | goto done; | |
609 | ||
610 | /* | |
611 | * If there is already a copy-out version of this buffer, then we don't | |
612 | * need to make another one | |
613 | */ | |
614 | if (jh->b_frozen_data) { | |
615 | JBUFFER_TRACE(jh, "has frozen data"); | |
616 | J_ASSERT_JH(jh, jh->b_next_transaction == NULL); | |
617 | jh->b_next_transaction = transaction; | |
618 | goto done; | |
619 | } | |
620 | ||
621 | /* Is there data here we need to preserve? */ | |
622 | ||
623 | if (jh->b_transaction && jh->b_transaction != transaction) { | |
624 | JBUFFER_TRACE(jh, "owned by older transaction"); | |
625 | J_ASSERT_JH(jh, jh->b_next_transaction == NULL); | |
626 | J_ASSERT_JH(jh, jh->b_transaction == | |
627 | journal->j_committing_transaction); | |
628 | ||
629 | /* There is one case we have to be very careful about. | |
630 | * If the committing transaction is currently writing | |
631 | * this buffer out to disk and has NOT made a copy-out, | |
632 | * then we cannot modify the buffer contents at all | |
633 | * right now. The essence of copy-out is that it is the | |
634 | * extra copy, not the primary copy, which gets | |
635 | * journaled. If the primary copy is already going to | |
636 | * disk then we cannot do copy-out here. */ | |
637 | ||
638 | if (jh->b_jlist == BJ_Shadow) { | |
639 | DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow); | |
640 | wait_queue_head_t *wqh; | |
641 | ||
642 | wqh = bit_waitqueue(&bh->b_state, BH_Unshadow); | |
643 | ||
644 | JBUFFER_TRACE(jh, "on shadow: sleep"); | |
645 | jbd_unlock_bh_state(bh); | |
646 | /* commit wakes up all shadow buffers after IO */ | |
647 | for ( ; ; ) { | |
648 | prepare_to_wait(wqh, &wait.wait, | |
649 | TASK_UNINTERRUPTIBLE); | |
650 | if (jh->b_jlist != BJ_Shadow) | |
651 | break; | |
652 | schedule(); | |
653 | } | |
654 | finish_wait(wqh, &wait.wait); | |
655 | goto repeat; | |
656 | } | |
657 | ||
658 | /* Only do the copy if the currently-owning transaction | |
659 | * still needs it. If it is on the Forget list, the | |
660 | * committing transaction is past that stage. The | |
661 | * buffer had better remain locked during the kmalloc, | |
662 | * but that should be true --- we hold the journal lock | |
663 | * still and the buffer is already on the BUF_JOURNAL | |
ae6ddcc5 | 664 | * list so won't be flushed. |
1da177e4 LT |
665 | * |
666 | * Subtle point, though: if this is a get_undo_access, | |
667 | * then we will be relying on the frozen_data to contain | |
668 | * the new value of the committed_data record after the | |
669 | * transaction, so we HAVE to force the frozen_data copy | |
670 | * in that case. */ | |
671 | ||
672 | if (jh->b_jlist != BJ_Forget || force_copy) { | |
673 | JBUFFER_TRACE(jh, "generate frozen data"); | |
674 | if (!frozen_buffer) { | |
675 | JBUFFER_TRACE(jh, "allocate memory for buffer"); | |
676 | jbd_unlock_bh_state(bh); | |
ea817398 | 677 | frozen_buffer = |
c089d490 | 678 | jbd_alloc(jh2bh(jh)->b_size, |
ea817398 | 679 | GFP_NOFS); |
1da177e4 LT |
680 | if (!frozen_buffer) { |
681 | printk(KERN_EMERG | |
682 | "%s: OOM for frozen_buffer\n", | |
683 | __FUNCTION__); | |
684 | JBUFFER_TRACE(jh, "oom!"); | |
685 | error = -ENOMEM; | |
686 | jbd_lock_bh_state(bh); | |
687 | goto done; | |
688 | } | |
689 | goto repeat; | |
690 | } | |
691 | jh->b_frozen_data = frozen_buffer; | |
692 | frozen_buffer = NULL; | |
693 | need_copy = 1; | |
694 | } | |
695 | jh->b_next_transaction = transaction; | |
696 | } | |
697 | ||
698 | ||
699 | /* | |
700 | * Finally, if the buffer is not journaled right now, we need to make | |
701 | * sure it doesn't get written to disk before the caller actually | |
702 | * commits the new data | |
703 | */ | |
704 | if (!jh->b_transaction) { | |
705 | JBUFFER_TRACE(jh, "no transaction"); | |
706 | J_ASSERT_JH(jh, !jh->b_next_transaction); | |
707 | jh->b_transaction = transaction; | |
708 | JBUFFER_TRACE(jh, "file as BJ_Reserved"); | |
709 | spin_lock(&journal->j_list_lock); | |
710 | __journal_file_buffer(jh, transaction, BJ_Reserved); | |
711 | spin_unlock(&journal->j_list_lock); | |
712 | } | |
713 | ||
714 | done: | |
715 | if (need_copy) { | |
716 | struct page *page; | |
717 | int offset; | |
718 | char *source; | |
719 | ||
720 | J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)), | |
721 | "Possible IO failure.\n"); | |
722 | page = jh2bh(jh)->b_page; | |
723 | offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK; | |
724 | source = kmap_atomic(page, KM_USER0); | |
725 | memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size); | |
726 | kunmap_atomic(source, KM_USER0); | |
727 | } | |
728 | jbd_unlock_bh_state(bh); | |
729 | ||
730 | /* | |
731 | * If we are about to journal a buffer, then any revoke pending on it is | |
732 | * no longer valid | |
733 | */ | |
734 | journal_cancel_revoke(handle, jh); | |
735 | ||
736 | out: | |
304c4c84 | 737 | if (unlikely(frozen_buffer)) /* It's usually NULL */ |
c089d490 | 738 | jbd_free(frozen_buffer, bh->b_size); |
1da177e4 LT |
739 | |
740 | JBUFFER_TRACE(jh, "exit"); | |
741 | return error; | |
742 | } | |
743 | ||
744 | /** | |
745 | * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update. | |
746 | * @handle: transaction to add buffer modifications to | |
747 | * @bh: bh to be used for metadata writes | |
748 | * @credits: variable that will receive credits for the buffer | |
749 | * | |
750 | * Returns an error code or 0 on success. | |
751 | * | |
752 | * In full data journalling mode the buffer may be of type BJ_AsyncData, | |
753 | * because we're write()ing a buffer which is also part of a shared mapping. | |
754 | */ | |
755 | ||
756 | int journal_get_write_access(handle_t *handle, struct buffer_head *bh) | |
757 | { | |
758 | struct journal_head *jh = journal_add_journal_head(bh); | |
759 | int rc; | |
760 | ||
761 | /* We do not want to get caught playing with fields which the | |
762 | * log thread also manipulates. Make sure that the buffer | |
763 | * completes any outstanding IO before proceeding. */ | |
764 | rc = do_get_write_access(handle, jh, 0); | |
765 | journal_put_journal_head(jh); | |
766 | return rc; | |
767 | } | |
768 | ||
769 | ||
770 | /* | |
771 | * When the user wants to journal a newly created buffer_head | |
772 | * (ie. getblk() returned a new buffer and we are going to populate it | |
773 | * manually rather than reading off disk), then we need to keep the | |
774 | * buffer_head locked until it has been completely filled with new | |
775 | * data. In this case, we should be able to make the assertion that | |
ae6ddcc5 MC |
776 | * the bh is not already part of an existing transaction. |
777 | * | |
1da177e4 LT |
778 | * The buffer should already be locked by the caller by this point. |
779 | * There is no lock ranking violation: it was a newly created, | |
780 | * unlocked buffer beforehand. */ | |
781 | ||
782 | /** | |
783 | * int journal_get_create_access () - notify intent to use newly created bh | |
784 | * @handle: transaction to new buffer to | |
785 | * @bh: new buffer. | |
786 | * | |
787 | * Call this if you create a new bh. | |
788 | */ | |
ae6ddcc5 | 789 | int journal_get_create_access(handle_t *handle, struct buffer_head *bh) |
1da177e4 LT |
790 | { |
791 | transaction_t *transaction = handle->h_transaction; | |
792 | journal_t *journal = transaction->t_journal; | |
793 | struct journal_head *jh = journal_add_journal_head(bh); | |
794 | int err; | |
795 | ||
796 | jbd_debug(5, "journal_head %p\n", jh); | |
797 | err = -EROFS; | |
798 | if (is_handle_aborted(handle)) | |
799 | goto out; | |
800 | err = 0; | |
801 | ||
802 | JBUFFER_TRACE(jh, "entry"); | |
803 | /* | |
804 | * The buffer may already belong to this transaction due to pre-zeroing | |
805 | * in the filesystem's new_block code. It may also be on the previous, | |
806 | * committing transaction's lists, but it HAS to be in Forget state in | |
807 | * that case: the transaction must have deleted the buffer for it to be | |
808 | * reused here. | |
809 | */ | |
810 | jbd_lock_bh_state(bh); | |
811 | spin_lock(&journal->j_list_lock); | |
812 | J_ASSERT_JH(jh, (jh->b_transaction == transaction || | |
813 | jh->b_transaction == NULL || | |
814 | (jh->b_transaction == journal->j_committing_transaction && | |
815 | jh->b_jlist == BJ_Forget))); | |
816 | ||
817 | J_ASSERT_JH(jh, jh->b_next_transaction == NULL); | |
818 | J_ASSERT_JH(jh, buffer_locked(jh2bh(jh))); | |
819 | ||
820 | if (jh->b_transaction == NULL) { | |
821 | jh->b_transaction = transaction; | |
822 | JBUFFER_TRACE(jh, "file as BJ_Reserved"); | |
823 | __journal_file_buffer(jh, transaction, BJ_Reserved); | |
824 | } else if (jh->b_transaction == journal->j_committing_transaction) { | |
825 | JBUFFER_TRACE(jh, "set next transaction"); | |
826 | jh->b_next_transaction = transaction; | |
827 | } | |
828 | spin_unlock(&journal->j_list_lock); | |
829 | jbd_unlock_bh_state(bh); | |
830 | ||
831 | /* | |
832 | * akpm: I added this. ext3_alloc_branch can pick up new indirect | |
833 | * blocks which contain freed but then revoked metadata. We need | |
834 | * to cancel the revoke in case we end up freeing it yet again | |
835 | * and the reallocating as data - this would cause a second revoke, | |
836 | * which hits an assertion error. | |
837 | */ | |
838 | JBUFFER_TRACE(jh, "cancelling revoke"); | |
839 | journal_cancel_revoke(handle, jh); | |
840 | journal_put_journal_head(jh); | |
841 | out: | |
842 | return err; | |
843 | } | |
844 | ||
845 | /** | |
846 | * int journal_get_undo_access() - Notify intent to modify metadata with | |
847 | * non-rewindable consequences | |
848 | * @handle: transaction | |
849 | * @bh: buffer to undo | |
850 | * @credits: store the number of taken credits here (if not NULL) | |
851 | * | |
852 | * Sometimes there is a need to distinguish between metadata which has | |
853 | * been committed to disk and that which has not. The ext3fs code uses | |
854 | * this for freeing and allocating space, we have to make sure that we | |
855 | * do not reuse freed space until the deallocation has been committed, | |
856 | * since if we overwrote that space we would make the delete | |
857 | * un-rewindable in case of a crash. | |
ae6ddcc5 | 858 | * |
1da177e4 LT |
859 | * To deal with that, journal_get_undo_access requests write access to a |
860 | * buffer for parts of non-rewindable operations such as delete | |
861 | * operations on the bitmaps. The journaling code must keep a copy of | |
862 | * the buffer's contents prior to the undo_access call until such time | |
863 | * as we know that the buffer has definitely been committed to disk. | |
ae6ddcc5 | 864 | * |
1da177e4 LT |
865 | * We never need to know which transaction the committed data is part |
866 | * of, buffers touched here are guaranteed to be dirtied later and so | |
867 | * will be committed to a new transaction in due course, at which point | |
868 | * we can discard the old committed data pointer. | |
869 | * | |
870 | * Returns error number or 0 on success. | |
871 | */ | |
872 | int journal_get_undo_access(handle_t *handle, struct buffer_head *bh) | |
873 | { | |
874 | int err; | |
875 | struct journal_head *jh = journal_add_journal_head(bh); | |
876 | char *committed_data = NULL; | |
877 | ||
878 | JBUFFER_TRACE(jh, "entry"); | |
879 | ||
880 | /* | |
881 | * Do this first --- it can drop the journal lock, so we want to | |
882 | * make sure that obtaining the committed_data is done | |
883 | * atomically wrt. completion of any outstanding commits. | |
884 | */ | |
885 | err = do_get_write_access(handle, jh, 1); | |
886 | if (err) | |
887 | goto out; | |
888 | ||
889 | repeat: | |
890 | if (!jh->b_committed_data) { | |
c089d490 | 891 | committed_data = jbd_alloc(jh2bh(jh)->b_size, GFP_NOFS); |
1da177e4 LT |
892 | if (!committed_data) { |
893 | printk(KERN_EMERG "%s: No memory for committed data\n", | |
894 | __FUNCTION__); | |
895 | err = -ENOMEM; | |
896 | goto out; | |
897 | } | |
898 | } | |
899 | ||
900 | jbd_lock_bh_state(bh); | |
901 | if (!jh->b_committed_data) { | |
902 | /* Copy out the current buffer contents into the | |
903 | * preserved, committed copy. */ | |
904 | JBUFFER_TRACE(jh, "generate b_committed data"); | |
905 | if (!committed_data) { | |
906 | jbd_unlock_bh_state(bh); | |
907 | goto repeat; | |
908 | } | |
909 | ||
910 | jh->b_committed_data = committed_data; | |
911 | committed_data = NULL; | |
912 | memcpy(jh->b_committed_data, bh->b_data, bh->b_size); | |
913 | } | |
914 | jbd_unlock_bh_state(bh); | |
915 | out: | |
916 | journal_put_journal_head(jh); | |
304c4c84 | 917 | if (unlikely(committed_data)) |
c089d490 | 918 | jbd_free(committed_data, bh->b_size); |
1da177e4 LT |
919 | return err; |
920 | } | |
921 | ||
ae6ddcc5 | 922 | /** |
1da177e4 LT |
923 | * int journal_dirty_data() - mark a buffer as containing dirty data which |
924 | * needs to be flushed before we can commit the | |
ae6ddcc5 | 925 | * current transaction. |
1da177e4 LT |
926 | * @handle: transaction |
927 | * @bh: bufferhead to mark | |
ae6ddcc5 | 928 | * |
1da177e4 LT |
929 | * The buffer is placed on the transaction's data list and is marked as |
930 | * belonging to the transaction. | |
931 | * | |
932 | * Returns error number or 0 on success. | |
933 | * | |
934 | * journal_dirty_data() can be called via page_launder->ext3_writepage | |
935 | * by kswapd. | |
936 | */ | |
937 | int journal_dirty_data(handle_t *handle, struct buffer_head *bh) | |
938 | { | |
939 | journal_t *journal = handle->h_transaction->t_journal; | |
940 | int need_brelse = 0; | |
941 | struct journal_head *jh; | |
942 | ||
943 | if (is_handle_aborted(handle)) | |
944 | return 0; | |
945 | ||
946 | jh = journal_add_journal_head(bh); | |
947 | JBUFFER_TRACE(jh, "entry"); | |
948 | ||
949 | /* | |
950 | * The buffer could *already* be dirty. Writeout can start | |
951 | * at any time. | |
952 | */ | |
953 | jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid); | |
954 | ||
955 | /* | |
956 | * What if the buffer is already part of a running transaction? | |
ae6ddcc5 | 957 | * |
1da177e4 LT |
958 | * There are two cases: |
959 | * 1) It is part of the current running transaction. Refile it, | |
960 | * just in case we have allocated it as metadata, deallocated | |
ae6ddcc5 | 961 | * it, then reallocated it as data. |
1da177e4 LT |
962 | * 2) It is part of the previous, still-committing transaction. |
963 | * If all we want to do is to guarantee that the buffer will be | |
964 | * written to disk before this new transaction commits, then | |
ae6ddcc5 | 965 | * being sure that the *previous* transaction has this same |
1da177e4 LT |
966 | * property is sufficient for us! Just leave it on its old |
967 | * transaction. | |
968 | * | |
969 | * In case (2), the buffer must not already exist as metadata | |
970 | * --- that would violate write ordering (a transaction is free | |
971 | * to write its data at any point, even before the previous | |
972 | * committing transaction has committed). The caller must | |
973 | * never, ever allow this to happen: there's nothing we can do | |
974 | * about it in this layer. | |
975 | */ | |
976 | jbd_lock_bh_state(bh); | |
977 | spin_lock(&journal->j_list_lock); | |
f58a74dc ES |
978 | |
979 | /* Now that we have bh_state locked, are we really still mapped? */ | |
980 | if (!buffer_mapped(bh)) { | |
981 | JBUFFER_TRACE(jh, "unmapped buffer, bailing out"); | |
982 | goto no_journal; | |
983 | } | |
984 | ||
1da177e4 LT |
985 | if (jh->b_transaction) { |
986 | JBUFFER_TRACE(jh, "has transaction"); | |
987 | if (jh->b_transaction != handle->h_transaction) { | |
988 | JBUFFER_TRACE(jh, "belongs to older transaction"); | |
989 | J_ASSERT_JH(jh, jh->b_transaction == | |
990 | journal->j_committing_transaction); | |
991 | ||
992 | /* @@@ IS THIS TRUE ? */ | |
993 | /* | |
994 | * Not any more. Scenario: someone does a write() | |
995 | * in data=journal mode. The buffer's transaction has | |
996 | * moved into commit. Then someone does another | |
997 | * write() to the file. We do the frozen data copyout | |
998 | * and set b_next_transaction to point to j_running_t. | |
999 | * And while we're in that state, someone does a | |
1000 | * writepage() in an attempt to pageout the same area | |
1001 | * of the file via a shared mapping. At present that | |
1002 | * calls journal_dirty_data(), and we get right here. | |
1003 | * It may be too late to journal the data. Simply | |
1004 | * falling through to the next test will suffice: the | |
1005 | * data will be dirty and wil be checkpointed. The | |
1006 | * ordering comments in the next comment block still | |
1007 | * apply. | |
1008 | */ | |
1009 | //J_ASSERT_JH(jh, jh->b_next_transaction == NULL); | |
1010 | ||
1011 | /* | |
1012 | * If we're journalling data, and this buffer was | |
1013 | * subject to a write(), it could be metadata, forget | |
1014 | * or shadow against the committing transaction. Now, | |
1015 | * someone has dirtied the same darn page via a mapping | |
1016 | * and it is being writepage()'d. | |
1017 | * We *could* just steal the page from commit, with some | |
1018 | * fancy locking there. Instead, we just skip it - | |
1019 | * don't tie the page's buffers to the new transaction | |
1020 | * at all. | |
1021 | * Implication: if we crash before the writepage() data | |
1022 | * is written into the filesystem, recovery will replay | |
1023 | * the write() data. | |
1024 | */ | |
1025 | if (jh->b_jlist != BJ_None && | |
1026 | jh->b_jlist != BJ_SyncData && | |
1027 | jh->b_jlist != BJ_Locked) { | |
1028 | JBUFFER_TRACE(jh, "Not stealing"); | |
1029 | goto no_journal; | |
1030 | } | |
1031 | ||
1032 | /* | |
1033 | * This buffer may be undergoing writeout in commit. We | |
1034 | * can't return from here and let the caller dirty it | |
1035 | * again because that can cause the write-out loop in | |
1036 | * commit to never terminate. | |
1037 | */ | |
1038 | if (buffer_dirty(bh)) { | |
1039 | get_bh(bh); | |
1040 | spin_unlock(&journal->j_list_lock); | |
1041 | jbd_unlock_bh_state(bh); | |
1042 | need_brelse = 1; | |
1043 | sync_dirty_buffer(bh); | |
1044 | jbd_lock_bh_state(bh); | |
1045 | spin_lock(&journal->j_list_lock); | |
f58a74dc ES |
1046 | /* Since we dropped the lock... */ |
1047 | if (!buffer_mapped(bh)) { | |
1048 | JBUFFER_TRACE(jh, "buffer got unmapped"); | |
1049 | goto no_journal; | |
1050 | } | |
1da177e4 LT |
1051 | /* The buffer may become locked again at any |
1052 | time if it is redirtied */ | |
1053 | } | |
1054 | ||
1055 | /* journal_clean_data_list() may have got there first */ | |
1056 | if (jh->b_transaction != NULL) { | |
1057 | JBUFFER_TRACE(jh, "unfile from commit"); | |
1058 | __journal_temp_unlink_buffer(jh); | |
1059 | /* It still points to the committing | |
1060 | * transaction; move it to this one so | |
1061 | * that the refile assert checks are | |
1062 | * happy. */ | |
1063 | jh->b_transaction = handle->h_transaction; | |
1064 | } | |
1065 | /* The buffer will be refiled below */ | |
1066 | ||
1067 | } | |
1068 | /* | |
1069 | * Special case --- the buffer might actually have been | |
1070 | * allocated and then immediately deallocated in the previous, | |
1071 | * committing transaction, so might still be left on that | |
1072 | * transaction's metadata lists. | |
1073 | */ | |
1074 | if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) { | |
1075 | JBUFFER_TRACE(jh, "not on correct data list: unfile"); | |
1076 | J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow); | |
1077 | __journal_temp_unlink_buffer(jh); | |
1078 | jh->b_transaction = handle->h_transaction; | |
1079 | JBUFFER_TRACE(jh, "file as data"); | |
1080 | __journal_file_buffer(jh, handle->h_transaction, | |
1081 | BJ_SyncData); | |
1082 | } | |
1083 | } else { | |
1084 | JBUFFER_TRACE(jh, "not on a transaction"); | |
1085 | __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData); | |
1086 | } | |
1087 | no_journal: | |
1088 | spin_unlock(&journal->j_list_lock); | |
1089 | jbd_unlock_bh_state(bh); | |
1090 | if (need_brelse) { | |
1091 | BUFFER_TRACE(bh, "brelse"); | |
1092 | __brelse(bh); | |
1093 | } | |
1094 | JBUFFER_TRACE(jh, "exit"); | |
1095 | journal_put_journal_head(jh); | |
1096 | return 0; | |
1097 | } | |
1098 | ||
ae6ddcc5 | 1099 | /** |
1da177e4 LT |
1100 | * int journal_dirty_metadata() - mark a buffer as containing dirty metadata |
1101 | * @handle: transaction to add buffer to. | |
ae6ddcc5 MC |
1102 | * @bh: buffer to mark |
1103 | * | |
1da177e4 LT |
1104 | * mark dirty metadata which needs to be journaled as part of the current |
1105 | * transaction. | |
1106 | * | |
1107 | * The buffer is placed on the transaction's metadata list and is marked | |
ae6ddcc5 | 1108 | * as belonging to the transaction. |
1da177e4 | 1109 | * |
ae6ddcc5 | 1110 | * Returns error number or 0 on success. |
1da177e4 LT |
1111 | * |
1112 | * Special care needs to be taken if the buffer already belongs to the | |
1113 | * current committing transaction (in which case we should have frozen | |
1114 | * data present for that commit). In that case, we don't relink the | |
1115 | * buffer: that only gets done when the old transaction finally | |
1116 | * completes its commit. | |
1117 | */ | |
1118 | int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) | |
1119 | { | |
1120 | transaction_t *transaction = handle->h_transaction; | |
1121 | journal_t *journal = transaction->t_journal; | |
1122 | struct journal_head *jh = bh2jh(bh); | |
1123 | ||
1124 | jbd_debug(5, "journal_head %p\n", jh); | |
1125 | JBUFFER_TRACE(jh, "entry"); | |
1126 | if (is_handle_aborted(handle)) | |
1127 | goto out; | |
1128 | ||
1129 | jbd_lock_bh_state(bh); | |
1130 | ||
1131 | if (jh->b_modified == 0) { | |
1132 | /* | |
1133 | * This buffer's got modified and becoming part | |
1134 | * of the transaction. This needs to be done | |
1135 | * once a transaction -bzzz | |
1136 | */ | |
1137 | jh->b_modified = 1; | |
1138 | J_ASSERT_JH(jh, handle->h_buffer_credits > 0); | |
1139 | handle->h_buffer_credits--; | |
1140 | } | |
1141 | ||
1142 | /* | |
1143 | * fastpath, to avoid expensive locking. If this buffer is already | |
1144 | * on the running transaction's metadata list there is nothing to do. | |
1145 | * Nobody can take it off again because there is a handle open. | |
1146 | * I _think_ we're OK here with SMP barriers - a mistaken decision will | |
1147 | * result in this test being false, so we go in and take the locks. | |
1148 | */ | |
1149 | if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) { | |
1150 | JBUFFER_TRACE(jh, "fastpath"); | |
1151 | J_ASSERT_JH(jh, jh->b_transaction == | |
1152 | journal->j_running_transaction); | |
1153 | goto out_unlock_bh; | |
1154 | } | |
1155 | ||
1156 | set_buffer_jbddirty(bh); | |
1157 | ||
ae6ddcc5 | 1158 | /* |
1da177e4 LT |
1159 | * Metadata already on the current transaction list doesn't |
1160 | * need to be filed. Metadata on another transaction's list must | |
1161 | * be committing, and will be refiled once the commit completes: | |
ae6ddcc5 | 1162 | * leave it alone for now. |
1da177e4 LT |
1163 | */ |
1164 | if (jh->b_transaction != transaction) { | |
1165 | JBUFFER_TRACE(jh, "already on other transaction"); | |
1166 | J_ASSERT_JH(jh, jh->b_transaction == | |
1167 | journal->j_committing_transaction); | |
1168 | J_ASSERT_JH(jh, jh->b_next_transaction == transaction); | |
1169 | /* And this case is illegal: we can't reuse another | |
1170 | * transaction's data buffer, ever. */ | |
1171 | goto out_unlock_bh; | |
1172 | } | |
1173 | ||
1174 | /* That test should have eliminated the following case: */ | |
1175 | J_ASSERT_JH(jh, jh->b_frozen_data == 0); | |
1176 | ||
1177 | JBUFFER_TRACE(jh, "file as BJ_Metadata"); | |
1178 | spin_lock(&journal->j_list_lock); | |
1179 | __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata); | |
1180 | spin_unlock(&journal->j_list_lock); | |
1181 | out_unlock_bh: | |
1182 | jbd_unlock_bh_state(bh); | |
1183 | out: | |
1184 | JBUFFER_TRACE(jh, "exit"); | |
1185 | return 0; | |
1186 | } | |
1187 | ||
ae6ddcc5 | 1188 | /* |
1da177e4 LT |
1189 | * journal_release_buffer: undo a get_write_access without any buffer |
1190 | * updates, if the update decided in the end that it didn't need access. | |
1191 | * | |
1192 | */ | |
1193 | void | |
1194 | journal_release_buffer(handle_t *handle, struct buffer_head *bh) | |
1195 | { | |
1196 | BUFFER_TRACE(bh, "entry"); | |
1197 | } | |
1198 | ||
ae6ddcc5 | 1199 | /** |
1da177e4 LT |
1200 | * void journal_forget() - bforget() for potentially-journaled buffers. |
1201 | * @handle: transaction handle | |
1202 | * @bh: bh to 'forget' | |
1203 | * | |
1204 | * We can only do the bforget if there are no commits pending against the | |
1205 | * buffer. If the buffer is dirty in the current running transaction we | |
ae6ddcc5 | 1206 | * can safely unlink it. |
1da177e4 LT |
1207 | * |
1208 | * bh may not be a journalled buffer at all - it may be a non-JBD | |
1209 | * buffer which came off the hashtable. Check for this. | |
1210 | * | |
1211 | * Decrements bh->b_count by one. | |
ae6ddcc5 | 1212 | * |
1da177e4 LT |
1213 | * Allow this call even if the handle has aborted --- it may be part of |
1214 | * the caller's cleanup after an abort. | |
1215 | */ | |
1216 | int journal_forget (handle_t *handle, struct buffer_head *bh) | |
1217 | { | |
1218 | transaction_t *transaction = handle->h_transaction; | |
1219 | journal_t *journal = transaction->t_journal; | |
1220 | struct journal_head *jh; | |
1221 | int drop_reserve = 0; | |
1222 | int err = 0; | |
1223 | ||
1224 | BUFFER_TRACE(bh, "entry"); | |
1225 | ||
1226 | jbd_lock_bh_state(bh); | |
1227 | spin_lock(&journal->j_list_lock); | |
1228 | ||
1229 | if (!buffer_jbd(bh)) | |
1230 | goto not_jbd; | |
1231 | jh = bh2jh(bh); | |
1232 | ||
1233 | /* Critical error: attempting to delete a bitmap buffer, maybe? | |
1234 | * Don't do any jbd operations, and return an error. */ | |
1235 | if (!J_EXPECT_JH(jh, !jh->b_committed_data, | |
1236 | "inconsistent data on disk")) { | |
1237 | err = -EIO; | |
1238 | goto not_jbd; | |
1239 | } | |
1240 | ||
1241 | /* | |
1242 | * The buffer's going from the transaction, we must drop | |
1243 | * all references -bzzz | |
1244 | */ | |
1245 | jh->b_modified = 0; | |
1246 | ||
1247 | if (jh->b_transaction == handle->h_transaction) { | |
1248 | J_ASSERT_JH(jh, !jh->b_frozen_data); | |
1249 | ||
1250 | /* If we are forgetting a buffer which is already part | |
1251 | * of this transaction, then we can just drop it from | |
1252 | * the transaction immediately. */ | |
1253 | clear_buffer_dirty(bh); | |
1254 | clear_buffer_jbddirty(bh); | |
1255 | ||
1256 | JBUFFER_TRACE(jh, "belongs to current transaction: unfile"); | |
1257 | ||
1258 | drop_reserve = 1; | |
1259 | ||
ae6ddcc5 | 1260 | /* |
1da177e4 LT |
1261 | * We are no longer going to journal this buffer. |
1262 | * However, the commit of this transaction is still | |
1263 | * important to the buffer: the delete that we are now | |
1264 | * processing might obsolete an old log entry, so by | |
1265 | * committing, we can satisfy the buffer's checkpoint. | |
1266 | * | |
1267 | * So, if we have a checkpoint on the buffer, we should | |
1268 | * now refile the buffer on our BJ_Forget list so that | |
ae6ddcc5 | 1269 | * we know to remove the checkpoint after we commit. |
1da177e4 LT |
1270 | */ |
1271 | ||
1272 | if (jh->b_cp_transaction) { | |
1273 | __journal_temp_unlink_buffer(jh); | |
1274 | __journal_file_buffer(jh, transaction, BJ_Forget); | |
1275 | } else { | |
1276 | __journal_unfile_buffer(jh); | |
1277 | journal_remove_journal_head(bh); | |
1278 | __brelse(bh); | |
1279 | if (!buffer_jbd(bh)) { | |
1280 | spin_unlock(&journal->j_list_lock); | |
1281 | jbd_unlock_bh_state(bh); | |
1282 | __bforget(bh); | |
1283 | goto drop; | |
1284 | } | |
1285 | } | |
1286 | } else if (jh->b_transaction) { | |
ae6ddcc5 | 1287 | J_ASSERT_JH(jh, (jh->b_transaction == |
1da177e4 LT |
1288 | journal->j_committing_transaction)); |
1289 | /* However, if the buffer is still owned by a prior | |
1290 | * (committing) transaction, we can't drop it yet... */ | |
1291 | JBUFFER_TRACE(jh, "belongs to older transaction"); | |
1292 | /* ... but we CAN drop it from the new transaction if we | |
1293 | * have also modified it since the original commit. */ | |
1294 | ||
1295 | if (jh->b_next_transaction) { | |
1296 | J_ASSERT(jh->b_next_transaction == transaction); | |
1297 | jh->b_next_transaction = NULL; | |
1298 | drop_reserve = 1; | |
1299 | } | |
1300 | } | |
1301 | ||
1302 | not_jbd: | |
1303 | spin_unlock(&journal->j_list_lock); | |
1304 | jbd_unlock_bh_state(bh); | |
1305 | __brelse(bh); | |
1306 | drop: | |
1307 | if (drop_reserve) { | |
1308 | /* no need to reserve log space for this block -bzzz */ | |
1309 | handle->h_buffer_credits++; | |
1310 | } | |
1311 | return err; | |
1312 | } | |
1313 | ||
1314 | /** | |
1315 | * int journal_stop() - complete a transaction | |
1316 | * @handle: tranaction to complete. | |
ae6ddcc5 | 1317 | * |
1da177e4 LT |
1318 | * All done for a particular handle. |
1319 | * | |
1320 | * There is not much action needed here. We just return any remaining | |
1321 | * buffer credits to the transaction and remove the handle. The only | |
1322 | * complication is that we need to start a commit operation if the | |
1323 | * filesystem is marked for synchronous update. | |
1324 | * | |
1325 | * journal_stop itself will not usually return an error, but it may | |
ae6ddcc5 | 1326 | * do so in unusual circumstances. In particular, expect it to |
1da177e4 LT |
1327 | * return -EIO if a journal_abort has been executed since the |
1328 | * transaction began. | |
1329 | */ | |
1330 | int journal_stop(handle_t *handle) | |
1331 | { | |
1332 | transaction_t *transaction = handle->h_transaction; | |
1333 | journal_t *journal = transaction->t_journal; | |
1334 | int old_handle_count, err; | |
fe1dcbc4 | 1335 | pid_t pid; |
1da177e4 | 1336 | |
1da177e4 LT |
1337 | J_ASSERT(journal_current_handle() == handle); |
1338 | ||
1339 | if (is_handle_aborted(handle)) | |
1340 | err = -EIO; | |
3e2a532b OH |
1341 | else { |
1342 | J_ASSERT(transaction->t_updates > 0); | |
1da177e4 | 1343 | err = 0; |
3e2a532b | 1344 | } |
1da177e4 LT |
1345 | |
1346 | if (--handle->h_ref > 0) { | |
1347 | jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1, | |
1348 | handle->h_ref); | |
1349 | return err; | |
1350 | } | |
1351 | ||
1352 | jbd_debug(4, "Handle %p going down\n", handle); | |
1353 | ||
1354 | /* | |
1355 | * Implement synchronous transaction batching. If the handle | |
1356 | * was synchronous, don't force a commit immediately. Let's | |
1357 | * yield and let another thread piggyback onto this transaction. | |
1358 | * Keep doing that while new threads continue to arrive. | |
1359 | * It doesn't cost much - we're about to run a commit and sleep | |
1360 | * on IO anyway. Speeds up many-threaded, many-dir operations | |
1361 | * by 30x or more... | |
fe1dcbc4 AM |
1362 | * |
1363 | * But don't do this if this process was the most recent one to | |
1364 | * perform a synchronous write. We do this to detect the case where a | |
1365 | * single process is doing a stream of sync writes. No point in waiting | |
1366 | * for joiners in that case. | |
1da177e4 | 1367 | */ |
fe1dcbc4 AM |
1368 | pid = current->pid; |
1369 | if (handle->h_sync && journal->j_last_sync_writer != pid) { | |
1370 | journal->j_last_sync_writer = pid; | |
1da177e4 LT |
1371 | do { |
1372 | old_handle_count = transaction->t_handle_count; | |
041e0e3b | 1373 | schedule_timeout_uninterruptible(1); |
1da177e4 LT |
1374 | } while (old_handle_count != transaction->t_handle_count); |
1375 | } | |
1376 | ||
1377 | current->journal_info = NULL; | |
1378 | spin_lock(&journal->j_state_lock); | |
1379 | spin_lock(&transaction->t_handle_lock); | |
1380 | transaction->t_outstanding_credits -= handle->h_buffer_credits; | |
1381 | transaction->t_updates--; | |
1382 | if (!transaction->t_updates) { | |
1383 | wake_up(&journal->j_wait_updates); | |
1384 | if (journal->j_barrier_count) | |
1385 | wake_up(&journal->j_wait_transaction_locked); | |
1386 | } | |
1387 | ||
1388 | /* | |
1389 | * If the handle is marked SYNC, we need to set another commit | |
1390 | * going! We also want to force a commit if the current | |
1391 | * transaction is occupying too much of the log, or if the | |
1392 | * transaction is too old now. | |
1393 | */ | |
1394 | if (handle->h_sync || | |
1395 | transaction->t_outstanding_credits > | |
1396 | journal->j_max_transaction_buffers || | |
e9ad5620 | 1397 | time_after_eq(jiffies, transaction->t_expires)) { |
1da177e4 LT |
1398 | /* Do this even for aborted journals: an abort still |
1399 | * completes the commit thread, it just doesn't write | |
1400 | * anything to disk. */ | |
1401 | tid_t tid = transaction->t_tid; | |
1402 | ||
1403 | spin_unlock(&transaction->t_handle_lock); | |
1404 | jbd_debug(2, "transaction too old, requesting commit for " | |
1405 | "handle %p\n", handle); | |
1406 | /* This is non-blocking */ | |
1407 | __log_start_commit(journal, transaction->t_tid); | |
1408 | spin_unlock(&journal->j_state_lock); | |
1409 | ||
1410 | /* | |
1411 | * Special case: JFS_SYNC synchronous updates require us | |
ae6ddcc5 | 1412 | * to wait for the commit to complete. |
1da177e4 LT |
1413 | */ |
1414 | if (handle->h_sync && !(current->flags & PF_MEMALLOC)) | |
1415 | err = log_wait_commit(journal, tid); | |
1416 | } else { | |
1417 | spin_unlock(&transaction->t_handle_lock); | |
1418 | spin_unlock(&journal->j_state_lock); | |
1419 | } | |
1420 | ||
34a3d1e8 PZ |
1421 | lock_release(&handle->h_lockdep_map, 1, _THIS_IP_); |
1422 | ||
1da177e4 LT |
1423 | jbd_free_handle(handle); |
1424 | return err; | |
1425 | } | |
1426 | ||
1427 | /**int journal_force_commit() - force any uncommitted transactions | |
1428 | * @journal: journal to force | |
1429 | * | |
1430 | * For synchronous operations: force any uncommitted transactions | |
1431 | * to disk. May seem kludgy, but it reuses all the handle batching | |
1432 | * code in a very simple manner. | |
1433 | */ | |
1434 | int journal_force_commit(journal_t *journal) | |
1435 | { | |
1436 | handle_t *handle; | |
1437 | int ret; | |
1438 | ||
1439 | handle = journal_start(journal, 1); | |
1440 | if (IS_ERR(handle)) { | |
1441 | ret = PTR_ERR(handle); | |
1442 | } else { | |
1443 | handle->h_sync = 1; | |
1444 | ret = journal_stop(handle); | |
1445 | } | |
1446 | return ret; | |
1447 | } | |
1448 | ||
1449 | /* | |
1450 | * | |
1451 | * List management code snippets: various functions for manipulating the | |
1452 | * transaction buffer lists. | |
1453 | * | |
1454 | */ | |
1455 | ||
1456 | /* | |
1457 | * Append a buffer to a transaction list, given the transaction's list head | |
1458 | * pointer. | |
1459 | * | |
1460 | * j_list_lock is held. | |
1461 | * | |
1462 | * jbd_lock_bh_state(jh2bh(jh)) is held. | |
1463 | */ | |
1464 | ||
ae6ddcc5 | 1465 | static inline void |
1da177e4 LT |
1466 | __blist_add_buffer(struct journal_head **list, struct journal_head *jh) |
1467 | { | |
1468 | if (!*list) { | |
1469 | jh->b_tnext = jh->b_tprev = jh; | |
1470 | *list = jh; | |
1471 | } else { | |
1472 | /* Insert at the tail of the list to preserve order */ | |
1473 | struct journal_head *first = *list, *last = first->b_tprev; | |
1474 | jh->b_tprev = last; | |
1475 | jh->b_tnext = first; | |
1476 | last->b_tnext = first->b_tprev = jh; | |
1477 | } | |
1478 | } | |
1479 | ||
ae6ddcc5 | 1480 | /* |
1da177e4 LT |
1481 | * Remove a buffer from a transaction list, given the transaction's list |
1482 | * head pointer. | |
1483 | * | |
1484 | * Called with j_list_lock held, and the journal may not be locked. | |
1485 | * | |
1486 | * jbd_lock_bh_state(jh2bh(jh)) is held. | |
1487 | */ | |
1488 | ||
1489 | static inline void | |
1490 | __blist_del_buffer(struct journal_head **list, struct journal_head *jh) | |
1491 | { | |
1492 | if (*list == jh) { | |
1493 | *list = jh->b_tnext; | |
1494 | if (*list == jh) | |
1495 | *list = NULL; | |
1496 | } | |
1497 | jh->b_tprev->b_tnext = jh->b_tnext; | |
1498 | jh->b_tnext->b_tprev = jh->b_tprev; | |
1499 | } | |
1500 | ||
ae6ddcc5 | 1501 | /* |
1da177e4 LT |
1502 | * Remove a buffer from the appropriate transaction list. |
1503 | * | |
1504 | * Note that this function can *change* the value of | |
1505 | * bh->b_transaction->t_sync_datalist, t_buffers, t_forget, | |
1506 | * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller | |
1507 | * is holding onto a copy of one of thee pointers, it could go bad. | |
1508 | * Generally the caller needs to re-read the pointer from the transaction_t. | |
1509 | * | |
1510 | * Called under j_list_lock. The journal may not be locked. | |
1511 | */ | |
d394e122 | 1512 | static void __journal_temp_unlink_buffer(struct journal_head *jh) |
1da177e4 LT |
1513 | { |
1514 | struct journal_head **list = NULL; | |
1515 | transaction_t *transaction; | |
1516 | struct buffer_head *bh = jh2bh(jh); | |
1517 | ||
1518 | J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); | |
1519 | transaction = jh->b_transaction; | |
1520 | if (transaction) | |
1521 | assert_spin_locked(&transaction->t_journal->j_list_lock); | |
1522 | ||
1523 | J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); | |
1524 | if (jh->b_jlist != BJ_None) | |
1525 | J_ASSERT_JH(jh, transaction != 0); | |
1526 | ||
1527 | switch (jh->b_jlist) { | |
1528 | case BJ_None: | |
1529 | return; | |
1530 | case BJ_SyncData: | |
1531 | list = &transaction->t_sync_datalist; | |
1532 | break; | |
1533 | case BJ_Metadata: | |
1534 | transaction->t_nr_buffers--; | |
1535 | J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0); | |
1536 | list = &transaction->t_buffers; | |
1537 | break; | |
1538 | case BJ_Forget: | |
1539 | list = &transaction->t_forget; | |
1540 | break; | |
1541 | case BJ_IO: | |
1542 | list = &transaction->t_iobuf_list; | |
1543 | break; | |
1544 | case BJ_Shadow: | |
1545 | list = &transaction->t_shadow_list; | |
1546 | break; | |
1547 | case BJ_LogCtl: | |
1548 | list = &transaction->t_log_list; | |
1549 | break; | |
1550 | case BJ_Reserved: | |
1551 | list = &transaction->t_reserved_list; | |
1552 | break; | |
1553 | case BJ_Locked: | |
1554 | list = &transaction->t_locked_list; | |
1555 | break; | |
1556 | } | |
1557 | ||
1558 | __blist_del_buffer(list, jh); | |
1559 | jh->b_jlist = BJ_None; | |
1560 | if (test_clear_buffer_jbddirty(bh)) | |
1561 | mark_buffer_dirty(bh); /* Expose it to the VM */ | |
1562 | } | |
1563 | ||
1564 | void __journal_unfile_buffer(struct journal_head *jh) | |
1565 | { | |
1566 | __journal_temp_unlink_buffer(jh); | |
1567 | jh->b_transaction = NULL; | |
1568 | } | |
1569 | ||
1570 | void journal_unfile_buffer(journal_t *journal, struct journal_head *jh) | |
1571 | { | |
1572 | jbd_lock_bh_state(jh2bh(jh)); | |
1573 | spin_lock(&journal->j_list_lock); | |
1574 | __journal_unfile_buffer(jh); | |
1575 | spin_unlock(&journal->j_list_lock); | |
1576 | jbd_unlock_bh_state(jh2bh(jh)); | |
1577 | } | |
1578 | ||
1579 | /* | |
1580 | * Called from journal_try_to_free_buffers(). | |
1581 | * | |
1582 | * Called under jbd_lock_bh_state(bh) | |
1583 | */ | |
1584 | static void | |
1585 | __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh) | |
1586 | { | |
1587 | struct journal_head *jh; | |
1588 | ||
1589 | jh = bh2jh(bh); | |
1590 | ||
1591 | if (buffer_locked(bh) || buffer_dirty(bh)) | |
1592 | goto out; | |
1593 | ||
1594 | if (jh->b_next_transaction != 0) | |
1595 | goto out; | |
1596 | ||
1597 | spin_lock(&journal->j_list_lock); | |
1598 | if (jh->b_transaction != 0 && jh->b_cp_transaction == 0) { | |
1599 | if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) { | |
1600 | /* A written-back ordered data buffer */ | |
1601 | JBUFFER_TRACE(jh, "release data"); | |
1602 | __journal_unfile_buffer(jh); | |
1603 | journal_remove_journal_head(bh); | |
1604 | __brelse(bh); | |
1605 | } | |
1606 | } else if (jh->b_cp_transaction != 0 && jh->b_transaction == 0) { | |
1607 | /* written-back checkpointed metadata buffer */ | |
1608 | if (jh->b_jlist == BJ_None) { | |
1609 | JBUFFER_TRACE(jh, "remove from checkpoint list"); | |
1610 | __journal_remove_checkpoint(jh); | |
1611 | journal_remove_journal_head(bh); | |
1612 | __brelse(bh); | |
1613 | } | |
1614 | } | |
1615 | spin_unlock(&journal->j_list_lock); | |
1616 | out: | |
1617 | return; | |
1618 | } | |
1619 | ||
1620 | ||
ae6ddcc5 | 1621 | /** |
1da177e4 LT |
1622 | * int journal_try_to_free_buffers() - try to free page buffers. |
1623 | * @journal: journal for operation | |
1624 | * @page: to try and free | |
1625 | * @unused_gfp_mask: unused | |
1626 | * | |
ae6ddcc5 | 1627 | * |
1da177e4 LT |
1628 | * For all the buffers on this page, |
1629 | * if they are fully written out ordered data, move them onto BUF_CLEAN | |
1630 | * so try_to_free_buffers() can reap them. | |
ae6ddcc5 | 1631 | * |
1da177e4 LT |
1632 | * This function returns non-zero if we wish try_to_free_buffers() |
1633 | * to be called. We do this if the page is releasable by try_to_free_buffers(). | |
1634 | * We also do it if the page has locked or dirty buffers and the caller wants | |
1635 | * us to perform sync or async writeout. | |
1636 | * | |
1637 | * This complicates JBD locking somewhat. We aren't protected by the | |
1638 | * BKL here. We wish to remove the buffer from its committing or | |
1639 | * running transaction's ->t_datalist via __journal_unfile_buffer. | |
1640 | * | |
1641 | * This may *change* the value of transaction_t->t_datalist, so anyone | |
1642 | * who looks at t_datalist needs to lock against this function. | |
1643 | * | |
1644 | * Even worse, someone may be doing a journal_dirty_data on this | |
1645 | * buffer. So we need to lock against that. journal_dirty_data() | |
1646 | * will come out of the lock with the buffer dirty, which makes it | |
1647 | * ineligible for release here. | |
1648 | * | |
1649 | * Who else is affected by this? hmm... Really the only contender | |
1650 | * is do_get_write_access() - it could be looking at the buffer while | |
1651 | * journal_try_to_free_buffer() is changing its state. But that | |
1652 | * cannot happen because we never reallocate freed data as metadata | |
1653 | * while the data is part of a transaction. Yes? | |
1654 | */ | |
ae6ddcc5 | 1655 | int journal_try_to_free_buffers(journal_t *journal, |
27496a8c | 1656 | struct page *page, gfp_t unused_gfp_mask) |
1da177e4 LT |
1657 | { |
1658 | struct buffer_head *head; | |
1659 | struct buffer_head *bh; | |
1660 | int ret = 0; | |
1661 | ||
1662 | J_ASSERT(PageLocked(page)); | |
1663 | ||
1664 | head = page_buffers(page); | |
1665 | bh = head; | |
1666 | do { | |
1667 | struct journal_head *jh; | |
1668 | ||
1669 | /* | |
1670 | * We take our own ref against the journal_head here to avoid | |
1671 | * having to add tons of locking around each instance of | |
1672 | * journal_remove_journal_head() and journal_put_journal_head(). | |
1673 | */ | |
1674 | jh = journal_grab_journal_head(bh); | |
1675 | if (!jh) | |
1676 | continue; | |
1677 | ||
1678 | jbd_lock_bh_state(bh); | |
1679 | __journal_try_to_free_buffer(journal, bh); | |
1680 | journal_put_journal_head(jh); | |
1681 | jbd_unlock_bh_state(bh); | |
1682 | if (buffer_jbd(bh)) | |
1683 | goto busy; | |
1684 | } while ((bh = bh->b_this_page) != head); | |
1685 | ret = try_to_free_buffers(page); | |
1686 | busy: | |
1687 | return ret; | |
1688 | } | |
1689 | ||
1690 | /* | |
1691 | * This buffer is no longer needed. If it is on an older transaction's | |
1692 | * checkpoint list we need to record it on this transaction's forget list | |
1693 | * to pin this buffer (and hence its checkpointing transaction) down until | |
1694 | * this transaction commits. If the buffer isn't on a checkpoint list, we | |
1695 | * release it. | |
1696 | * Returns non-zero if JBD no longer has an interest in the buffer. | |
1697 | * | |
1698 | * Called under j_list_lock. | |
1699 | * | |
1700 | * Called under jbd_lock_bh_state(bh). | |
1701 | */ | |
1702 | static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction) | |
1703 | { | |
1704 | int may_free = 1; | |
1705 | struct buffer_head *bh = jh2bh(jh); | |
1706 | ||
1707 | __journal_unfile_buffer(jh); | |
1708 | ||
1709 | if (jh->b_cp_transaction) { | |
1710 | JBUFFER_TRACE(jh, "on running+cp transaction"); | |
1711 | __journal_file_buffer(jh, transaction, BJ_Forget); | |
1712 | clear_buffer_jbddirty(bh); | |
1713 | may_free = 0; | |
1714 | } else { | |
1715 | JBUFFER_TRACE(jh, "on running transaction"); | |
1716 | journal_remove_journal_head(bh); | |
1717 | __brelse(bh); | |
1718 | } | |
1719 | return may_free; | |
1720 | } | |
1721 | ||
1722 | /* | |
ae6ddcc5 | 1723 | * journal_invalidatepage |
1da177e4 LT |
1724 | * |
1725 | * This code is tricky. It has a number of cases to deal with. | |
1726 | * | |
1727 | * There are two invariants which this code relies on: | |
1728 | * | |
1729 | * i_size must be updated on disk before we start calling invalidatepage on the | |
1730 | * data. | |
ae6ddcc5 | 1731 | * |
1da177e4 LT |
1732 | * This is done in ext3 by defining an ext3_setattr method which |
1733 | * updates i_size before truncate gets going. By maintaining this | |
1734 | * invariant, we can be sure that it is safe to throw away any buffers | |
1735 | * attached to the current transaction: once the transaction commits, | |
1736 | * we know that the data will not be needed. | |
ae6ddcc5 | 1737 | * |
1da177e4 | 1738 | * Note however that we can *not* throw away data belonging to the |
ae6ddcc5 | 1739 | * previous, committing transaction! |
1da177e4 LT |
1740 | * |
1741 | * Any disk blocks which *are* part of the previous, committing | |
1742 | * transaction (and which therefore cannot be discarded immediately) are | |
1743 | * not going to be reused in the new running transaction | |
1744 | * | |
1745 | * The bitmap committed_data images guarantee this: any block which is | |
1746 | * allocated in one transaction and removed in the next will be marked | |
1747 | * as in-use in the committed_data bitmap, so cannot be reused until | |
1748 | * the next transaction to delete the block commits. This means that | |
1749 | * leaving committing buffers dirty is quite safe: the disk blocks | |
1750 | * cannot be reallocated to a different file and so buffer aliasing is | |
1751 | * not possible. | |
1752 | * | |
1753 | * | |
1754 | * The above applies mainly to ordered data mode. In writeback mode we | |
1755 | * don't make guarantees about the order in which data hits disk --- in | |
1756 | * particular we don't guarantee that new dirty data is flushed before | |
1757 | * transaction commit --- so it is always safe just to discard data | |
ae6ddcc5 | 1758 | * immediately in that mode. --sct |
1da177e4 LT |
1759 | */ |
1760 | ||
1761 | /* | |
1762 | * The journal_unmap_buffer helper function returns zero if the buffer | |
1763 | * concerned remains pinned as an anonymous buffer belonging to an older | |
1764 | * transaction. | |
1765 | * | |
1766 | * We're outside-transaction here. Either or both of j_running_transaction | |
1767 | * and j_committing_transaction may be NULL. | |
1768 | */ | |
1769 | static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh) | |
1770 | { | |
1771 | transaction_t *transaction; | |
1772 | struct journal_head *jh; | |
1773 | int may_free = 1; | |
1774 | int ret; | |
1775 | ||
1776 | BUFFER_TRACE(bh, "entry"); | |
1777 | ||
1778 | /* | |
1779 | * It is safe to proceed here without the j_list_lock because the | |
1780 | * buffers cannot be stolen by try_to_free_buffers as long as we are | |
1781 | * holding the page lock. --sct | |
1782 | */ | |
1783 | ||
1784 | if (!buffer_jbd(bh)) | |
1785 | goto zap_buffer_unlocked; | |
1786 | ||
1787 | spin_lock(&journal->j_state_lock); | |
1788 | jbd_lock_bh_state(bh); | |
1789 | spin_lock(&journal->j_list_lock); | |
1790 | ||
1791 | jh = journal_grab_journal_head(bh); | |
1792 | if (!jh) | |
1793 | goto zap_buffer_no_jh; | |
1794 | ||
1795 | transaction = jh->b_transaction; | |
1796 | if (transaction == NULL) { | |
1797 | /* First case: not on any transaction. If it | |
1798 | * has no checkpoint link, then we can zap it: | |
1799 | * it's a writeback-mode buffer so we don't care | |
1800 | * if it hits disk safely. */ | |
1801 | if (!jh->b_cp_transaction) { | |
1802 | JBUFFER_TRACE(jh, "not on any transaction: zap"); | |
1803 | goto zap_buffer; | |
1804 | } | |
1805 | ||
1806 | if (!buffer_dirty(bh)) { | |
1807 | /* bdflush has written it. We can drop it now */ | |
1808 | goto zap_buffer; | |
1809 | } | |
1810 | ||
1811 | /* OK, it must be in the journal but still not | |
1812 | * written fully to disk: it's metadata or | |
1813 | * journaled data... */ | |
1814 | ||
1815 | if (journal->j_running_transaction) { | |
1816 | /* ... and once the current transaction has | |
1817 | * committed, the buffer won't be needed any | |
1818 | * longer. */ | |
1819 | JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget"); | |
1820 | ret = __dispose_buffer(jh, | |
1821 | journal->j_running_transaction); | |
1822 | journal_put_journal_head(jh); | |
1823 | spin_unlock(&journal->j_list_lock); | |
1824 | jbd_unlock_bh_state(bh); | |
1825 | spin_unlock(&journal->j_state_lock); | |
1826 | return ret; | |
1827 | } else { | |
1828 | /* There is no currently-running transaction. So the | |
1829 | * orphan record which we wrote for this file must have | |
1830 | * passed into commit. We must attach this buffer to | |
1831 | * the committing transaction, if it exists. */ | |
1832 | if (journal->j_committing_transaction) { | |
1833 | JBUFFER_TRACE(jh, "give to committing trans"); | |
1834 | ret = __dispose_buffer(jh, | |
1835 | journal->j_committing_transaction); | |
1836 | journal_put_journal_head(jh); | |
1837 | spin_unlock(&journal->j_list_lock); | |
1838 | jbd_unlock_bh_state(bh); | |
1839 | spin_unlock(&journal->j_state_lock); | |
1840 | return ret; | |
1841 | } else { | |
1842 | /* The orphan record's transaction has | |
1843 | * committed. We can cleanse this buffer */ | |
1844 | clear_buffer_jbddirty(bh); | |
1845 | goto zap_buffer; | |
1846 | } | |
1847 | } | |
1848 | } else if (transaction == journal->j_committing_transaction) { | |
f58a74dc | 1849 | JBUFFER_TRACE(jh, "on committing transaction"); |
d13df84f AM |
1850 | if (jh->b_jlist == BJ_Locked) { |
1851 | /* | |
1852 | * The buffer is on the committing transaction's locked | |
1853 | * list. We have the buffer locked, so I/O has | |
1854 | * completed. So we can nail the buffer now. | |
1855 | */ | |
1856 | may_free = __dispose_buffer(jh, transaction); | |
1857 | goto zap_buffer; | |
1858 | } | |
1859 | /* | |
1860 | * If it is committing, we simply cannot touch it. We | |
1da177e4 LT |
1861 | * can remove it's next_transaction pointer from the |
1862 | * running transaction if that is set, but nothing | |
1863 | * else. */ | |
1da177e4 LT |
1864 | set_buffer_freed(bh); |
1865 | if (jh->b_next_transaction) { | |
1866 | J_ASSERT(jh->b_next_transaction == | |
1867 | journal->j_running_transaction); | |
1868 | jh->b_next_transaction = NULL; | |
1869 | } | |
1870 | journal_put_journal_head(jh); | |
1871 | spin_unlock(&journal->j_list_lock); | |
1872 | jbd_unlock_bh_state(bh); | |
1873 | spin_unlock(&journal->j_state_lock); | |
1874 | return 0; | |
1875 | } else { | |
1876 | /* Good, the buffer belongs to the running transaction. | |
1877 | * We are writing our own transaction's data, not any | |
1878 | * previous one's, so it is safe to throw it away | |
1879 | * (remember that we expect the filesystem to have set | |
1880 | * i_size already for this truncate so recovery will not | |
1881 | * expose the disk blocks we are discarding here.) */ | |
1882 | J_ASSERT_JH(jh, transaction == journal->j_running_transaction); | |
f58a74dc | 1883 | JBUFFER_TRACE(jh, "on running transaction"); |
1da177e4 LT |
1884 | may_free = __dispose_buffer(jh, transaction); |
1885 | } | |
1886 | ||
1887 | zap_buffer: | |
1888 | journal_put_journal_head(jh); | |
1889 | zap_buffer_no_jh: | |
1890 | spin_unlock(&journal->j_list_lock); | |
1891 | jbd_unlock_bh_state(bh); | |
1892 | spin_unlock(&journal->j_state_lock); | |
1893 | zap_buffer_unlocked: | |
1894 | clear_buffer_dirty(bh); | |
1895 | J_ASSERT_BH(bh, !buffer_jbddirty(bh)); | |
1896 | clear_buffer_mapped(bh); | |
1897 | clear_buffer_req(bh); | |
1898 | clear_buffer_new(bh); | |
1899 | bh->b_bdev = NULL; | |
1900 | return may_free; | |
1901 | } | |
1902 | ||
ae6ddcc5 | 1903 | /** |
2ff28e22 | 1904 | * void journal_invalidatepage() |
ae6ddcc5 | 1905 | * @journal: journal to use for flush... |
1da177e4 LT |
1906 | * @page: page to flush |
1907 | * @offset: length of page to invalidate. | |
1908 | * | |
1909 | * Reap page buffers containing data after offset in page. | |
1910 | * | |
1da177e4 | 1911 | */ |
2ff28e22 | 1912 | void journal_invalidatepage(journal_t *journal, |
ae6ddcc5 | 1913 | struct page *page, |
1da177e4 LT |
1914 | unsigned long offset) |
1915 | { | |
1916 | struct buffer_head *head, *bh, *next; | |
1917 | unsigned int curr_off = 0; | |
1918 | int may_free = 1; | |
1919 | ||
1920 | if (!PageLocked(page)) | |
1921 | BUG(); | |
1922 | if (!page_has_buffers(page)) | |
2ff28e22 | 1923 | return; |
1da177e4 LT |
1924 | |
1925 | /* We will potentially be playing with lists other than just the | |
1926 | * data lists (especially for journaled data mode), so be | |
1927 | * cautious in our locking. */ | |
1928 | ||
1929 | head = bh = page_buffers(page); | |
1930 | do { | |
1931 | unsigned int next_off = curr_off + bh->b_size; | |
1932 | next = bh->b_this_page; | |
1933 | ||
1da177e4 | 1934 | if (offset <= curr_off) { |
e9ad5620 | 1935 | /* This block is wholly outside the truncation point */ |
1da177e4 LT |
1936 | lock_buffer(bh); |
1937 | may_free &= journal_unmap_buffer(journal, bh); | |
1938 | unlock_buffer(bh); | |
1939 | } | |
1940 | curr_off = next_off; | |
1941 | bh = next; | |
1942 | ||
1943 | } while (bh != head); | |
1944 | ||
1945 | if (!offset) { | |
2ff28e22 N |
1946 | if (may_free && try_to_free_buffers(page)) |
1947 | J_ASSERT(!page_has_buffers(page)); | |
1da177e4 | 1948 | } |
1da177e4 LT |
1949 | } |
1950 | ||
ae6ddcc5 MC |
1951 | /* |
1952 | * File a buffer on the given transaction list. | |
1da177e4 LT |
1953 | */ |
1954 | void __journal_file_buffer(struct journal_head *jh, | |
1955 | transaction_t *transaction, int jlist) | |
1956 | { | |
1957 | struct journal_head **list = NULL; | |
1958 | int was_dirty = 0; | |
1959 | struct buffer_head *bh = jh2bh(jh); | |
1960 | ||
1961 | J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); | |
1962 | assert_spin_locked(&transaction->t_journal->j_list_lock); | |
1963 | ||
1964 | J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); | |
1965 | J_ASSERT_JH(jh, jh->b_transaction == transaction || | |
1966 | jh->b_transaction == 0); | |
1967 | ||
1968 | if (jh->b_transaction && jh->b_jlist == jlist) | |
1969 | return; | |
1970 | ||
1971 | /* The following list of buffer states needs to be consistent | |
1972 | * with __jbd_unexpected_dirty_buffer()'s handling of dirty | |
1973 | * state. */ | |
1974 | ||
ae6ddcc5 | 1975 | if (jlist == BJ_Metadata || jlist == BJ_Reserved || |
1da177e4 LT |
1976 | jlist == BJ_Shadow || jlist == BJ_Forget) { |
1977 | if (test_clear_buffer_dirty(bh) || | |
1978 | test_clear_buffer_jbddirty(bh)) | |
1979 | was_dirty = 1; | |
1980 | } | |
1981 | ||
1982 | if (jh->b_transaction) | |
1983 | __journal_temp_unlink_buffer(jh); | |
1984 | jh->b_transaction = transaction; | |
1985 | ||
1986 | switch (jlist) { | |
1987 | case BJ_None: | |
1988 | J_ASSERT_JH(jh, !jh->b_committed_data); | |
1989 | J_ASSERT_JH(jh, !jh->b_frozen_data); | |
1990 | return; | |
1991 | case BJ_SyncData: | |
1992 | list = &transaction->t_sync_datalist; | |
1993 | break; | |
1994 | case BJ_Metadata: | |
1995 | transaction->t_nr_buffers++; | |
1996 | list = &transaction->t_buffers; | |
1997 | break; | |
1998 | case BJ_Forget: | |
1999 | list = &transaction->t_forget; | |
2000 | break; | |
2001 | case BJ_IO: | |
2002 | list = &transaction->t_iobuf_list; | |
2003 | break; | |
2004 | case BJ_Shadow: | |
2005 | list = &transaction->t_shadow_list; | |
2006 | break; | |
2007 | case BJ_LogCtl: | |
2008 | list = &transaction->t_log_list; | |
2009 | break; | |
2010 | case BJ_Reserved: | |
2011 | list = &transaction->t_reserved_list; | |
2012 | break; | |
2013 | case BJ_Locked: | |
2014 | list = &transaction->t_locked_list; | |
2015 | break; | |
2016 | } | |
2017 | ||
2018 | __blist_add_buffer(list, jh); | |
2019 | jh->b_jlist = jlist; | |
2020 | ||
2021 | if (was_dirty) | |
2022 | set_buffer_jbddirty(bh); | |
2023 | } | |
2024 | ||
2025 | void journal_file_buffer(struct journal_head *jh, | |
2026 | transaction_t *transaction, int jlist) | |
2027 | { | |
2028 | jbd_lock_bh_state(jh2bh(jh)); | |
2029 | spin_lock(&transaction->t_journal->j_list_lock); | |
2030 | __journal_file_buffer(jh, transaction, jlist); | |
2031 | spin_unlock(&transaction->t_journal->j_list_lock); | |
2032 | jbd_unlock_bh_state(jh2bh(jh)); | |
2033 | } | |
2034 | ||
ae6ddcc5 | 2035 | /* |
1da177e4 LT |
2036 | * Remove a buffer from its current buffer list in preparation for |
2037 | * dropping it from its current transaction entirely. If the buffer has | |
2038 | * already started to be used by a subsequent transaction, refile the | |
2039 | * buffer on that transaction's metadata list. | |
2040 | * | |
2041 | * Called under journal->j_list_lock | |
2042 | * | |
2043 | * Called under jbd_lock_bh_state(jh2bh(jh)) | |
2044 | */ | |
2045 | void __journal_refile_buffer(struct journal_head *jh) | |
2046 | { | |
2047 | int was_dirty; | |
2048 | struct buffer_head *bh = jh2bh(jh); | |
2049 | ||
2050 | J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); | |
2051 | if (jh->b_transaction) | |
2052 | assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock); | |
2053 | ||
2054 | /* If the buffer is now unused, just drop it. */ | |
2055 | if (jh->b_next_transaction == NULL) { | |
2056 | __journal_unfile_buffer(jh); | |
2057 | return; | |
2058 | } | |
2059 | ||
2060 | /* | |
2061 | * It has been modified by a later transaction: add it to the new | |
2062 | * transaction's metadata list. | |
2063 | */ | |
2064 | ||
2065 | was_dirty = test_clear_buffer_jbddirty(bh); | |
2066 | __journal_temp_unlink_buffer(jh); | |
2067 | jh->b_transaction = jh->b_next_transaction; | |
2068 | jh->b_next_transaction = NULL; | |
9ada7340 JK |
2069 | __journal_file_buffer(jh, jh->b_transaction, |
2070 | was_dirty ? BJ_Metadata : BJ_Reserved); | |
1da177e4 LT |
2071 | J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING); |
2072 | ||
2073 | if (was_dirty) | |
2074 | set_buffer_jbddirty(bh); | |
2075 | } | |
2076 | ||
2077 | /* | |
2078 | * For the unlocked version of this call, also make sure that any | |
2079 | * hanging journal_head is cleaned up if necessary. | |
2080 | * | |
2081 | * __journal_refile_buffer is usually called as part of a single locked | |
2082 | * operation on a buffer_head, in which the caller is probably going to | |
2083 | * be hooking the journal_head onto other lists. In that case it is up | |
2084 | * to the caller to remove the journal_head if necessary. For the | |
2085 | * unlocked journal_refile_buffer call, the caller isn't going to be | |
2086 | * doing anything else to the buffer so we need to do the cleanup | |
ae6ddcc5 | 2087 | * ourselves to avoid a jh leak. |
1da177e4 LT |
2088 | * |
2089 | * *** The journal_head may be freed by this call! *** | |
2090 | */ | |
2091 | void journal_refile_buffer(journal_t *journal, struct journal_head *jh) | |
2092 | { | |
2093 | struct buffer_head *bh = jh2bh(jh); | |
2094 | ||
2095 | jbd_lock_bh_state(bh); | |
2096 | spin_lock(&journal->j_list_lock); | |
2097 | ||
2098 | __journal_refile_buffer(jh); | |
2099 | jbd_unlock_bh_state(bh); | |
2100 | journal_remove_journal_head(bh); | |
2101 | ||
2102 | spin_unlock(&journal->j_list_lock); | |
2103 | __brelse(bh); | |
2104 | } |