xref: /openbmc/linux/fs/gfs2/log.c (revision 25b892b5)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
4  * Copyright (C) 2004-2007 Red Hat, Inc.  All rights reserved.
5  */
6 
7 #include <linux/sched.h>
8 #include <linux/slab.h>
9 #include <linux/spinlock.h>
10 #include <linux/completion.h>
11 #include <linux/buffer_head.h>
12 #include <linux/gfs2_ondisk.h>
13 #include <linux/crc32.h>
14 #include <linux/crc32c.h>
15 #include <linux/delay.h>
16 #include <linux/kthread.h>
17 #include <linux/freezer.h>
18 #include <linux/bio.h>
19 #include <linux/blkdev.h>
20 #include <linux/writeback.h>
21 #include <linux/list_sort.h>
22 
23 #include "gfs2.h"
24 #include "incore.h"
25 #include "bmap.h"
26 #include "glock.h"
27 #include "log.h"
28 #include "lops.h"
29 #include "meta_io.h"
30 #include "util.h"
31 #include "dir.h"
32 #include "trace_gfs2.h"
33 #include "trans.h"
34 
35 static void gfs2_log_shutdown(struct gfs2_sbd *sdp);
36 
37 /**
38  * gfs2_struct2blk - compute stuff
39  * @sdp: the filesystem
40  * @nstruct: the number of structures
41  *
42  * Compute the number of log descriptor blocks needed to hold a certain number
43  * of structures of a certain size.
44  *
45  * Returns: the number of blocks needed (minimum is always 1)
46  */
47 
48 unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct)
49 {
50 	unsigned int blks;
51 	unsigned int first, second;
52 
53 	/* The initial struct gfs2_log_descriptor block */
54 	blks = 1;
55 	first = sdp->sd_ldptrs;
56 
57 	if (nstruct > first) {
58 		/* Subsequent struct gfs2_meta_header blocks */
59 		second = sdp->sd_inptrs;
60 		blks += DIV_ROUND_UP(nstruct - first, second);
61 	}
62 
63 	return blks;
64 }
65 
66 /**
67  * gfs2_remove_from_ail - Remove an entry from the ail lists, updating counters
68  * @bd: The gfs2_bufdata to remove
69  *
70  * The ail lock _must_ be held when calling this function
71  *
72  */
73 
74 void gfs2_remove_from_ail(struct gfs2_bufdata *bd)
75 {
76 	bd->bd_tr = NULL;
77 	list_del_init(&bd->bd_ail_st_list);
78 	list_del_init(&bd->bd_ail_gl_list);
79 	atomic_dec(&bd->bd_gl->gl_ail_count);
80 	brelse(bd->bd_bh);
81 }
82 
83 /**
84  * gfs2_ail1_start_one - Start I/O on a transaction
85  * @sdp: The superblock
86  * @wbc: The writeback control structure
87  * @tr: The transaction to start I/O on
88  * @plug: The block plug currently active
89  */
90 
91 static int gfs2_ail1_start_one(struct gfs2_sbd *sdp,
92 			       struct writeback_control *wbc,
93 			       struct gfs2_trans *tr, struct blk_plug *plug)
94 __releases(&sdp->sd_ail_lock)
95 __acquires(&sdp->sd_ail_lock)
96 {
97 	struct gfs2_glock *gl = NULL;
98 	struct address_space *mapping;
99 	struct gfs2_bufdata *bd, *s;
100 	struct buffer_head *bh;
101 	int ret = 0;
102 
103 	list_for_each_entry_safe_reverse(bd, s, &tr->tr_ail1_list, bd_ail_st_list) {
104 		bh = bd->bd_bh;
105 
106 		gfs2_assert(sdp, bd->bd_tr == tr);
107 
108 		if (!buffer_busy(bh)) {
109 			if (buffer_uptodate(bh)) {
110 				list_move(&bd->bd_ail_st_list,
111 					  &tr->tr_ail2_list);
112 				continue;
113 			}
114 			if (!cmpxchg(&sdp->sd_log_error, 0, -EIO)) {
115 				gfs2_io_error_bh(sdp, bh);
116 				gfs2_withdraw_delayed(sdp);
117 			}
118 		}
119 
120 		if (gfs2_withdrawn(sdp)) {
121 			gfs2_remove_from_ail(bd);
122 			continue;
123 		}
124 		if (!buffer_dirty(bh))
125 			continue;
126 		if (gl == bd->bd_gl)
127 			continue;
128 		gl = bd->bd_gl;
129 		list_move(&bd->bd_ail_st_list, &tr->tr_ail1_list);
130 		mapping = bh->b_page->mapping;
131 		if (!mapping)
132 			continue;
133 		spin_unlock(&sdp->sd_ail_lock);
134 		ret = generic_writepages(mapping, wbc);
135 		if (need_resched()) {
136 			blk_finish_plug(plug);
137 			cond_resched();
138 			blk_start_plug(plug);
139 		}
140 		spin_lock(&sdp->sd_ail_lock);
141 		if (ret == -ENODATA) /* if a jdata write into a new hole */
142 			ret = 0; /* ignore it */
143 		if (ret || wbc->nr_to_write <= 0)
144 			break;
145 		return -EBUSY;
146 	}
147 
148 	return ret;
149 }
150 
151 static void dump_ail_list(struct gfs2_sbd *sdp)
152 {
153 	struct gfs2_trans *tr;
154 	struct gfs2_bufdata *bd;
155 	struct buffer_head *bh;
156 
157 	list_for_each_entry_reverse(tr, &sdp->sd_ail1_list, tr_list) {
158 		list_for_each_entry_reverse(bd, &tr->tr_ail1_list,
159 					    bd_ail_st_list) {
160 			bh = bd->bd_bh;
161 			fs_err(sdp, "bd %p: blk:0x%llx bh=%p ", bd,
162 			       (unsigned long long)bd->bd_blkno, bh);
163 			if (!bh) {
164 				fs_err(sdp, "\n");
165 				continue;
166 			}
167 			fs_err(sdp, "0x%llx up2:%d dirt:%d lkd:%d req:%d "
168 			       "map:%d new:%d ar:%d aw:%d delay:%d "
169 			       "io err:%d unwritten:%d dfr:%d pin:%d esc:%d\n",
170 			       (unsigned long long)bh->b_blocknr,
171 			       buffer_uptodate(bh), buffer_dirty(bh),
172 			       buffer_locked(bh), buffer_req(bh),
173 			       buffer_mapped(bh), buffer_new(bh),
174 			       buffer_async_read(bh), buffer_async_write(bh),
175 			       buffer_delay(bh), buffer_write_io_error(bh),
176 			       buffer_unwritten(bh),
177 			       buffer_defer_completion(bh),
178 			       buffer_pinned(bh), buffer_escaped(bh));
179 		}
180 	}
181 }
182 
183 /**
184  * gfs2_ail1_flush - start writeback of some ail1 entries
185  * @sdp: The super block
186  * @wbc: The writeback control structure
187  *
188  * Writes back some ail1 entries, according to the limits in the
189  * writeback control structure
190  */
191 
192 void gfs2_ail1_flush(struct gfs2_sbd *sdp, struct writeback_control *wbc)
193 {
194 	struct list_head *head = &sdp->sd_ail1_list;
195 	struct gfs2_trans *tr;
196 	struct blk_plug plug;
197 	int ret;
198 	unsigned long flush_start = jiffies;
199 
200 	trace_gfs2_ail_flush(sdp, wbc, 1);
201 	blk_start_plug(&plug);
202 	spin_lock(&sdp->sd_ail_lock);
203 restart:
204 	ret = 0;
205 	if (time_after(jiffies, flush_start + (HZ * 600))) {
206 		fs_err(sdp, "Error: In %s for ten minutes! t=%d\n",
207 		       __func__, current->journal_info ? 1 : 0);
208 		dump_ail_list(sdp);
209 		goto out;
210 	}
211 	list_for_each_entry_reverse(tr, head, tr_list) {
212 		if (wbc->nr_to_write <= 0)
213 			break;
214 		ret = gfs2_ail1_start_one(sdp, wbc, tr, &plug);
215 		if (ret) {
216 			if (ret == -EBUSY)
217 				goto restart;
218 			break;
219 		}
220 	}
221 out:
222 	spin_unlock(&sdp->sd_ail_lock);
223 	blk_finish_plug(&plug);
224 	if (ret) {
225 		gfs2_lm(sdp, "gfs2_ail1_start_one (generic_writepages) "
226 			"returned: %d\n", ret);
227 		gfs2_withdraw(sdp);
228 	}
229 	trace_gfs2_ail_flush(sdp, wbc, 0);
230 }
231 
232 /**
233  * gfs2_ail1_start - start writeback of all ail1 entries
234  * @sdp: The superblock
235  */
236 
237 static void gfs2_ail1_start(struct gfs2_sbd *sdp)
238 {
239 	struct writeback_control wbc = {
240 		.sync_mode = WB_SYNC_NONE,
241 		.nr_to_write = LONG_MAX,
242 		.range_start = 0,
243 		.range_end = LLONG_MAX,
244 	};
245 
246 	return gfs2_ail1_flush(sdp, &wbc);
247 }
248 
249 static void gfs2_log_update_flush_tail(struct gfs2_sbd *sdp)
250 {
251 	unsigned int new_flush_tail = sdp->sd_log_head;
252 	struct gfs2_trans *tr;
253 
254 	if (!list_empty(&sdp->sd_ail1_list)) {
255 		tr = list_last_entry(&sdp->sd_ail1_list,
256 				     struct gfs2_trans, tr_list);
257 		new_flush_tail = tr->tr_first;
258 	}
259 	sdp->sd_log_flush_tail = new_flush_tail;
260 }
261 
262 static void gfs2_log_update_head(struct gfs2_sbd *sdp)
263 {
264 	unsigned int new_head = sdp->sd_log_flush_head;
265 
266 	if (sdp->sd_log_flush_tail == sdp->sd_log_head)
267 		sdp->sd_log_flush_tail = new_head;
268 	sdp->sd_log_head = new_head;
269 }
270 
271 /*
272  * gfs2_ail_empty_tr - empty one of the ail lists of a transaction
273  */
274 
275 static void gfs2_ail_empty_tr(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
276 			      struct list_head *head)
277 {
278 	struct gfs2_bufdata *bd;
279 
280 	while (!list_empty(head)) {
281 		bd = list_first_entry(head, struct gfs2_bufdata,
282 				      bd_ail_st_list);
283 		gfs2_assert(sdp, bd->bd_tr == tr);
284 		gfs2_remove_from_ail(bd);
285 	}
286 }
287 
288 /**
289  * gfs2_ail1_empty_one - Check whether or not a trans in the AIL has been synced
290  * @sdp: the filesystem
291  * @tr: the transaction
292  * @max_revokes: If nonzero, issue revokes for the bd items for written buffers
293  *
294  * returns: the transaction's count of remaining active items
295  */
296 
297 static int gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
298 				int *max_revokes)
299 {
300 	struct gfs2_bufdata *bd, *s;
301 	struct buffer_head *bh;
302 	int active_count = 0;
303 
304 	list_for_each_entry_safe_reverse(bd, s, &tr->tr_ail1_list,
305 					 bd_ail_st_list) {
306 		bh = bd->bd_bh;
307 		gfs2_assert(sdp, bd->bd_tr == tr);
308 		/*
309 		 * If another process flagged an io error, e.g. writing to the
310 		 * journal, error all other bhs and move them off the ail1 to
311 		 * prevent a tight loop when unmount tries to flush ail1,
312 		 * regardless of whether they're still busy. If no outside
313 		 * errors were found and the buffer is busy, move to the next.
314 		 * If the ail buffer is not busy and caught an error, flag it
315 		 * for others.
316 		 */
317 		if (!sdp->sd_log_error && buffer_busy(bh)) {
318 			active_count++;
319 			continue;
320 		}
321 		if (!buffer_uptodate(bh) &&
322 		    !cmpxchg(&sdp->sd_log_error, 0, -EIO)) {
323 			gfs2_io_error_bh(sdp, bh);
324 			gfs2_withdraw_delayed(sdp);
325 		}
326 		/*
327 		 * If we have space for revokes and the bd is no longer on any
328 		 * buf list, we can just add a revoke for it immediately and
329 		 * avoid having to put it on the ail2 list, where it would need
330 		 * to be revoked later.
331 		 */
332 		if (*max_revokes && list_empty(&bd->bd_list)) {
333 			gfs2_add_revoke(sdp, bd);
334 			(*max_revokes)--;
335 			continue;
336 		}
337 		list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
338 	}
339 	return active_count;
340 }
341 
342 /**
343  * gfs2_ail1_empty - Try to empty the ail1 lists
344  * @sdp: The superblock
345  * @max_revokes: If non-zero, add revokes where appropriate
346  *
347  * Tries to empty the ail1 lists, starting with the oldest first
348  */
349 
350 static int gfs2_ail1_empty(struct gfs2_sbd *sdp, int max_revokes)
351 {
352 	struct gfs2_trans *tr, *s;
353 	int oldest_tr = 1;
354 	int ret;
355 
356 	spin_lock(&sdp->sd_ail_lock);
357 	list_for_each_entry_safe_reverse(tr, s, &sdp->sd_ail1_list, tr_list) {
358 		if (!gfs2_ail1_empty_one(sdp, tr, &max_revokes) && oldest_tr)
359 			list_move(&tr->tr_list, &sdp->sd_ail2_list);
360 		else
361 			oldest_tr = 0;
362 	}
363 	gfs2_log_update_flush_tail(sdp);
364 	ret = list_empty(&sdp->sd_ail1_list);
365 	spin_unlock(&sdp->sd_ail_lock);
366 
367 	if (test_bit(SDF_WITHDRAWING, &sdp->sd_flags)) {
368 		gfs2_lm(sdp, "fatal: I/O error(s)\n");
369 		gfs2_withdraw(sdp);
370 	}
371 
372 	return ret;
373 }
374 
375 static void gfs2_ail1_wait(struct gfs2_sbd *sdp)
376 {
377 	struct gfs2_trans *tr;
378 	struct gfs2_bufdata *bd;
379 	struct buffer_head *bh;
380 
381 	spin_lock(&sdp->sd_ail_lock);
382 	list_for_each_entry_reverse(tr, &sdp->sd_ail1_list, tr_list) {
383 		list_for_each_entry(bd, &tr->tr_ail1_list, bd_ail_st_list) {
384 			bh = bd->bd_bh;
385 			if (!buffer_locked(bh))
386 				continue;
387 			get_bh(bh);
388 			spin_unlock(&sdp->sd_ail_lock);
389 			wait_on_buffer(bh);
390 			brelse(bh);
391 			return;
392 		}
393 	}
394 	spin_unlock(&sdp->sd_ail_lock);
395 }
396 
397 static void __ail2_empty(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
398 {
399 	gfs2_ail_empty_tr(sdp, tr, &tr->tr_ail2_list);
400 	list_del(&tr->tr_list);
401 	gfs2_assert_warn(sdp, list_empty(&tr->tr_ail1_list));
402 	gfs2_assert_warn(sdp, list_empty(&tr->tr_ail2_list));
403 	gfs2_trans_free(sdp, tr);
404 }
405 
406 static void ail2_empty(struct gfs2_sbd *sdp, unsigned int new_tail)
407 {
408 	struct list_head *ail2_list = &sdp->sd_ail2_list;
409 	unsigned int old_tail = sdp->sd_log_tail;
410 	struct gfs2_trans *tr, *safe;
411 
412 	spin_lock(&sdp->sd_ail_lock);
413 	if (old_tail <= new_tail) {
414 		list_for_each_entry_safe(tr, safe, ail2_list, tr_list) {
415 			if (old_tail <= tr->tr_first && tr->tr_first < new_tail)
416 				__ail2_empty(sdp, tr);
417 		}
418 	} else {
419 		list_for_each_entry_safe(tr, safe, ail2_list, tr_list) {
420 			if (old_tail <= tr->tr_first || tr->tr_first < new_tail)
421 				__ail2_empty(sdp, tr);
422 		}
423 	}
424 	spin_unlock(&sdp->sd_ail_lock);
425 }
426 
427 /**
428  * gfs2_log_is_empty - Check if the log is empty
429  * @sdp: The GFS2 superblock
430  */
431 
432 bool gfs2_log_is_empty(struct gfs2_sbd *sdp) {
433 	return atomic_read(&sdp->sd_log_blks_free) == sdp->sd_jdesc->jd_blocks;
434 }
435 
436 static bool __gfs2_log_try_reserve_revokes(struct gfs2_sbd *sdp, unsigned int revokes)
437 {
438 	unsigned int available;
439 
440 	available = atomic_read(&sdp->sd_log_revokes_available);
441 	while (available >= revokes) {
442 		if (atomic_try_cmpxchg(&sdp->sd_log_revokes_available,
443 				       &available, available - revokes))
444 			return true;
445 	}
446 	return false;
447 }
448 
449 /**
450  * gfs2_log_release_revokes - Release a given number of revokes
451  * @sdp: The GFS2 superblock
452  * @revokes: The number of revokes to release
453  *
454  * sdp->sd_log_flush_lock must be held.
455  */
456 void gfs2_log_release_revokes(struct gfs2_sbd *sdp, unsigned int revokes)
457 {
458 	if (revokes)
459 		atomic_add(revokes, &sdp->sd_log_revokes_available);
460 }
461 
462 /**
463  * gfs2_log_release - Release a given number of log blocks
464  * @sdp: The GFS2 superblock
465  * @blks: The number of blocks
466  *
467  */
468 
469 void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks)
470 {
471 	atomic_add(blks, &sdp->sd_log_blks_free);
472 	trace_gfs2_log_blocks(sdp, blks);
473 	gfs2_assert_withdraw(sdp, atomic_read(&sdp->sd_log_blks_free) <=
474 				  sdp->sd_jdesc->jd_blocks);
475 	if (atomic_read(&sdp->sd_log_blks_needed))
476 		wake_up(&sdp->sd_log_waitq);
477 }
478 
479 /**
480  * __gfs2_log_try_reserve - Try to make a log reservation
481  * @sdp: The GFS2 superblock
482  * @blks: The number of blocks to reserve
483  * @taboo_blks: The number of blocks to leave free
484  *
485  * Try to do the same as __gfs2_log_reserve(), but fail if no more log
486  * space is immediately available.
487  */
488 static bool __gfs2_log_try_reserve(struct gfs2_sbd *sdp, unsigned int blks,
489 				   unsigned int taboo_blks)
490 {
491 	unsigned wanted = blks + taboo_blks;
492 	unsigned int free_blocks;
493 
494 	free_blocks = atomic_read(&sdp->sd_log_blks_free);
495 	while (free_blocks >= wanted) {
496 		if (atomic_try_cmpxchg(&sdp->sd_log_blks_free, &free_blocks,
497 				       free_blocks - blks)) {
498 			trace_gfs2_log_blocks(sdp, -blks);
499 			return true;
500 		}
501 	}
502 	return false;
503 }
504 
505 /**
506  * __gfs2_log_reserve - Make a log reservation
507  * @sdp: The GFS2 superblock
508  * @blks: The number of blocks to reserve
509  * @taboo_blks: The number of blocks to leave free
510  *
511  * @taboo_blks is set to 0 for logd, and to GFS2_LOG_FLUSH_MIN_BLOCKS
512  * for all other processes.  This ensures that when the log is almost full,
513  * logd will still be able to call gfs2_log_flush one more time  without
514  * blocking, which will advance the tail and make some more log space
515  * available.
516  *
517  * We no longer flush the log here, instead we wake up logd to do that
518  * for us. To avoid the thundering herd and to ensure that we deal fairly
519  * with queued waiters, we use an exclusive wait. This means that when we
520  * get woken with enough journal space to get our reservation, we need to
521  * wake the next waiter on the list.
522  */
523 
524 static void __gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks,
525 			       unsigned int taboo_blks)
526 {
527 	unsigned wanted = blks + taboo_blks;
528 	unsigned int free_blocks;
529 
530 	atomic_add(blks, &sdp->sd_log_blks_needed);
531 	for (;;) {
532 		if (current != sdp->sd_logd_process)
533 			wake_up(&sdp->sd_logd_waitq);
534 		io_wait_event(sdp->sd_log_waitq,
535 			(free_blocks = atomic_read(&sdp->sd_log_blks_free),
536 			 free_blocks >= wanted));
537 		do {
538 			if (atomic_try_cmpxchg(&sdp->sd_log_blks_free,
539 					       &free_blocks,
540 					       free_blocks - blks))
541 				goto reserved;
542 		} while (free_blocks >= wanted);
543 	}
544 
545 reserved:
546 	trace_gfs2_log_blocks(sdp, -blks);
547 	if (atomic_sub_return(blks, &sdp->sd_log_blks_needed))
548 		wake_up(&sdp->sd_log_waitq);
549 }
550 
551 /**
552  * gfs2_log_try_reserve - Try to make a log reservation
553  * @sdp: The GFS2 superblock
554  * @tr: The transaction
555  * @extra_revokes: The number of additional revokes reserved (output)
556  *
557  * This is similar to gfs2_log_reserve, but sdp->sd_log_flush_lock must be
558  * held for correct revoke accounting.
559  */
560 
561 bool gfs2_log_try_reserve(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
562 			  unsigned int *extra_revokes)
563 {
564 	unsigned int blks = tr->tr_reserved;
565 	unsigned int revokes = tr->tr_revokes;
566 	unsigned int revoke_blks = 0;
567 
568 	*extra_revokes = 0;
569 	if (revokes && !__gfs2_log_try_reserve_revokes(sdp, revokes)) {
570 		revoke_blks = DIV_ROUND_UP(revokes, sdp->sd_inptrs);
571 		*extra_revokes = revoke_blks * sdp->sd_inptrs - revokes;
572 		blks += revoke_blks;
573 	}
574 	if (!blks)
575 		return true;
576 	if (__gfs2_log_try_reserve(sdp, blks, GFS2_LOG_FLUSH_MIN_BLOCKS))
577 		return true;
578 	if (!revoke_blks)
579 		gfs2_log_release_revokes(sdp, revokes);
580 	return false;
581 }
582 
583 /**
584  * gfs2_log_reserve - Make a log reservation
585  * @sdp: The GFS2 superblock
586  * @tr: The transaction
587  * @extra_revokes: The number of additional revokes reserved (output)
588  *
589  * sdp->sd_log_flush_lock must not be held.
590  */
591 
592 void gfs2_log_reserve(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
593 		      unsigned int *extra_revokes)
594 {
595 	unsigned int blks = tr->tr_reserved;
596 	unsigned int revokes = tr->tr_revokes;
597 	unsigned int revoke_blks;
598 
599 	*extra_revokes = 0;
600 	if (revokes) {
601 		revoke_blks = DIV_ROUND_UP(revokes, sdp->sd_inptrs);
602 		*extra_revokes = revoke_blks * sdp->sd_inptrs - revokes;
603 		blks += revoke_blks;
604 	}
605 	__gfs2_log_reserve(sdp, blks, GFS2_LOG_FLUSH_MIN_BLOCKS);
606 }
607 
608 /**
609  * log_distance - Compute distance between two journal blocks
610  * @sdp: The GFS2 superblock
611  * @newer: The most recent journal block of the pair
612  * @older: The older journal block of the pair
613  *
614  *   Compute the distance (in the journal direction) between two
615  *   blocks in the journal
616  *
617  * Returns: the distance in blocks
618  */
619 
620 static inline unsigned int log_distance(struct gfs2_sbd *sdp, unsigned int newer,
621 					unsigned int older)
622 {
623 	int dist;
624 
625 	dist = newer - older;
626 	if (dist < 0)
627 		dist += sdp->sd_jdesc->jd_blocks;
628 
629 	return dist;
630 }
631 
632 /**
633  * calc_reserved - Calculate the number of blocks to keep reserved
634  * @sdp: The GFS2 superblock
635  *
636  * This is complex.  We need to reserve room for all our currently used
637  * metadata blocks (e.g. normal file I/O rewriting file time stamps) and
638  * all our journaled data blocks for journaled files (e.g. files in the
639  * meta_fs like rindex, or files for which chattr +j was done.)
640  * If we don't reserve enough space, corruption will follow.
641  *
642  * We can have metadata blocks and jdata blocks in the same journal.  Each
643  * type gets its own log descriptor, for which we need to reserve a block.
644  * In fact, each type has the potential for needing more than one log descriptor
645  * in cases where we have more blocks than will fit in a log descriptor.
646  * Metadata journal entries take up half the space of journaled buffer entries.
647  *
648  * Also, we need to reserve blocks for revoke journal entries and one for an
649  * overall header for the lot.
650  *
651  * Returns: the number of blocks reserved
652  */
653 static unsigned int calc_reserved(struct gfs2_sbd *sdp)
654 {
655 	unsigned int reserved = GFS2_LOG_FLUSH_MIN_BLOCKS;
656 	unsigned int blocks;
657 	struct gfs2_trans *tr = sdp->sd_log_tr;
658 
659 	if (tr) {
660 		blocks = tr->tr_num_buf_new - tr->tr_num_buf_rm;
661 		reserved += blocks + DIV_ROUND_UP(blocks, buf_limit(sdp));
662 		blocks = tr->tr_num_databuf_new - tr->tr_num_databuf_rm;
663 		reserved += blocks + DIV_ROUND_UP(blocks, databuf_limit(sdp));
664 	}
665 	return reserved;
666 }
667 
668 static void log_pull_tail(struct gfs2_sbd *sdp)
669 {
670 	unsigned int new_tail = sdp->sd_log_flush_tail;
671 	unsigned int dist;
672 
673 	if (new_tail == sdp->sd_log_tail)
674 		return;
675 	dist = log_distance(sdp, new_tail, sdp->sd_log_tail);
676 	ail2_empty(sdp, new_tail);
677 	gfs2_log_release(sdp, dist);
678 	sdp->sd_log_tail = new_tail;
679 }
680 
681 
682 void log_flush_wait(struct gfs2_sbd *sdp)
683 {
684 	DEFINE_WAIT(wait);
685 
686 	if (atomic_read(&sdp->sd_log_in_flight)) {
687 		do {
688 			prepare_to_wait(&sdp->sd_log_flush_wait, &wait,
689 					TASK_UNINTERRUPTIBLE);
690 			if (atomic_read(&sdp->sd_log_in_flight))
691 				io_schedule();
692 		} while(atomic_read(&sdp->sd_log_in_flight));
693 		finish_wait(&sdp->sd_log_flush_wait, &wait);
694 	}
695 }
696 
697 static int ip_cmp(void *priv, const struct list_head *a, const struct list_head *b)
698 {
699 	struct gfs2_inode *ipa, *ipb;
700 
701 	ipa = list_entry(a, struct gfs2_inode, i_ordered);
702 	ipb = list_entry(b, struct gfs2_inode, i_ordered);
703 
704 	if (ipa->i_no_addr < ipb->i_no_addr)
705 		return -1;
706 	if (ipa->i_no_addr > ipb->i_no_addr)
707 		return 1;
708 	return 0;
709 }
710 
711 static void __ordered_del_inode(struct gfs2_inode *ip)
712 {
713 	if (!list_empty(&ip->i_ordered))
714 		list_del_init(&ip->i_ordered);
715 }
716 
717 static void gfs2_ordered_write(struct gfs2_sbd *sdp)
718 {
719 	struct gfs2_inode *ip;
720 	LIST_HEAD(written);
721 
722 	spin_lock(&sdp->sd_ordered_lock);
723 	list_sort(NULL, &sdp->sd_log_ordered, &ip_cmp);
724 	while (!list_empty(&sdp->sd_log_ordered)) {
725 		ip = list_first_entry(&sdp->sd_log_ordered, struct gfs2_inode, i_ordered);
726 		if (ip->i_inode.i_mapping->nrpages == 0) {
727 			__ordered_del_inode(ip);
728 			continue;
729 		}
730 		list_move(&ip->i_ordered, &written);
731 		spin_unlock(&sdp->sd_ordered_lock);
732 		filemap_fdatawrite(ip->i_inode.i_mapping);
733 		spin_lock(&sdp->sd_ordered_lock);
734 	}
735 	list_splice(&written, &sdp->sd_log_ordered);
736 	spin_unlock(&sdp->sd_ordered_lock);
737 }
738 
739 static void gfs2_ordered_wait(struct gfs2_sbd *sdp)
740 {
741 	struct gfs2_inode *ip;
742 
743 	spin_lock(&sdp->sd_ordered_lock);
744 	while (!list_empty(&sdp->sd_log_ordered)) {
745 		ip = list_first_entry(&sdp->sd_log_ordered, struct gfs2_inode, i_ordered);
746 		__ordered_del_inode(ip);
747 		if (ip->i_inode.i_mapping->nrpages == 0)
748 			continue;
749 		spin_unlock(&sdp->sd_ordered_lock);
750 		filemap_fdatawait(ip->i_inode.i_mapping);
751 		spin_lock(&sdp->sd_ordered_lock);
752 	}
753 	spin_unlock(&sdp->sd_ordered_lock);
754 }
755 
756 void gfs2_ordered_del_inode(struct gfs2_inode *ip)
757 {
758 	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
759 
760 	spin_lock(&sdp->sd_ordered_lock);
761 	__ordered_del_inode(ip);
762 	spin_unlock(&sdp->sd_ordered_lock);
763 }
764 
765 void gfs2_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
766 {
767 	struct buffer_head *bh = bd->bd_bh;
768 	struct gfs2_glock *gl = bd->bd_gl;
769 
770 	sdp->sd_log_num_revoke++;
771 	if (atomic_inc_return(&gl->gl_revokes) == 1)
772 		gfs2_glock_hold(gl);
773 	bh->b_private = NULL;
774 	bd->bd_blkno = bh->b_blocknr;
775 	gfs2_remove_from_ail(bd); /* drops ref on bh */
776 	bd->bd_bh = NULL;
777 	set_bit(GLF_LFLUSH, &gl->gl_flags);
778 	list_add(&bd->bd_list, &sdp->sd_log_revokes);
779 }
780 
781 void gfs2_glock_remove_revoke(struct gfs2_glock *gl)
782 {
783 	if (atomic_dec_return(&gl->gl_revokes) == 0) {
784 		clear_bit(GLF_LFLUSH, &gl->gl_flags);
785 		gfs2_glock_queue_put(gl);
786 	}
787 }
788 
789 /**
790  * gfs2_flush_revokes - Add as many revokes to the system transaction as we can
791  * @sdp: The GFS2 superblock
792  *
793  * Our usual strategy is to defer writing revokes as much as we can in the hope
794  * that we'll eventually overwrite the journal, which will make those revokes
795  * go away.  This changes when we flush the log: at that point, there will
796  * likely be some left-over space in the last revoke block of that transaction.
797  * We can fill that space with additional revokes for blocks that have already
798  * been written back.  This will basically come at no cost now, and will save
799  * us from having to keep track of those blocks on the AIL2 list later.
800  */
801 void gfs2_flush_revokes(struct gfs2_sbd *sdp)
802 {
803 	/* number of revokes we still have room for */
804 	unsigned int max_revokes = atomic_read(&sdp->sd_log_revokes_available);
805 
806 	gfs2_log_lock(sdp);
807 	gfs2_ail1_empty(sdp, max_revokes);
808 	gfs2_log_unlock(sdp);
809 }
810 
811 /**
812  * gfs2_write_log_header - Write a journal log header buffer at lblock
813  * @sdp: The GFS2 superblock
814  * @jd: journal descriptor of the journal to which we are writing
815  * @seq: sequence number
816  * @tail: tail of the log
817  * @lblock: value for lh_blkno (block number relative to start of journal)
818  * @flags: log header flags GFS2_LOG_HEAD_*
819  * @op_flags: flags to pass to the bio
820  *
821  * Returns: the initialized log buffer descriptor
822  */
823 
824 void gfs2_write_log_header(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd,
825 			   u64 seq, u32 tail, u32 lblock, u32 flags,
826 			   int op_flags)
827 {
828 	struct gfs2_log_header *lh;
829 	u32 hash, crc;
830 	struct page *page;
831 	struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
832 	struct timespec64 tv;
833 	struct super_block *sb = sdp->sd_vfs;
834 	u64 dblock;
835 
836 	if (gfs2_withdrawn(sdp))
837 		return;
838 
839 	page = mempool_alloc(gfs2_page_pool, GFP_NOIO);
840 	lh = page_address(page);
841 	clear_page(lh);
842 
843 	lh->lh_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
844 	lh->lh_header.mh_type = cpu_to_be32(GFS2_METATYPE_LH);
845 	lh->lh_header.__pad0 = cpu_to_be64(0);
846 	lh->lh_header.mh_format = cpu_to_be32(GFS2_FORMAT_LH);
847 	lh->lh_header.mh_jid = cpu_to_be32(sdp->sd_jdesc->jd_jid);
848 	lh->lh_sequence = cpu_to_be64(seq);
849 	lh->lh_flags = cpu_to_be32(flags);
850 	lh->lh_tail = cpu_to_be32(tail);
851 	lh->lh_blkno = cpu_to_be32(lblock);
852 	hash = ~crc32(~0, lh, LH_V1_SIZE);
853 	lh->lh_hash = cpu_to_be32(hash);
854 
855 	ktime_get_coarse_real_ts64(&tv);
856 	lh->lh_nsec = cpu_to_be32(tv.tv_nsec);
857 	lh->lh_sec = cpu_to_be64(tv.tv_sec);
858 	if (!list_empty(&jd->extent_list))
859 		dblock = gfs2_log_bmap(jd, lblock);
860 	else {
861 		unsigned int extlen;
862 		int ret;
863 
864 		extlen = 1;
865 		ret = gfs2_get_extent(jd->jd_inode, lblock, &dblock, &extlen);
866 		if (gfs2_assert_withdraw(sdp, ret == 0))
867 			return;
868 	}
869 	lh->lh_addr = cpu_to_be64(dblock);
870 	lh->lh_jinode = cpu_to_be64(GFS2_I(jd->jd_inode)->i_no_addr);
871 
872 	/* We may only write local statfs, quota, etc., when writing to our
873 	   own journal. The values are left 0 when recovering a journal
874 	   different from our own. */
875 	if (!(flags & GFS2_LOG_HEAD_RECOVERY)) {
876 		lh->lh_statfs_addr =
877 			cpu_to_be64(GFS2_I(sdp->sd_sc_inode)->i_no_addr);
878 		lh->lh_quota_addr =
879 			cpu_to_be64(GFS2_I(sdp->sd_qc_inode)->i_no_addr);
880 
881 		spin_lock(&sdp->sd_statfs_spin);
882 		lh->lh_local_total = cpu_to_be64(l_sc->sc_total);
883 		lh->lh_local_free = cpu_to_be64(l_sc->sc_free);
884 		lh->lh_local_dinodes = cpu_to_be64(l_sc->sc_dinodes);
885 		spin_unlock(&sdp->sd_statfs_spin);
886 	}
887 
888 	BUILD_BUG_ON(offsetof(struct gfs2_log_header, lh_crc) != LH_V1_SIZE);
889 
890 	crc = crc32c(~0, (void *)lh + LH_V1_SIZE + 4,
891 		     sb->s_blocksize - LH_V1_SIZE - 4);
892 	lh->lh_crc = cpu_to_be32(crc);
893 
894 	gfs2_log_write(sdp, jd, page, sb->s_blocksize, 0, dblock);
895 	gfs2_log_submit_bio(&jd->jd_log_bio, REQ_OP_WRITE | op_flags);
896 }
897 
898 /**
899  * log_write_header - Get and initialize a journal header buffer
900  * @sdp: The GFS2 superblock
901  * @flags: The log header flags, including log header origin
902  *
903  * Returns: the initialized log buffer descriptor
904  */
905 
906 static void log_write_header(struct gfs2_sbd *sdp, u32 flags)
907 {
908 	int op_flags = REQ_PREFLUSH | REQ_FUA | REQ_META | REQ_SYNC;
909 	enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);
910 
911 	gfs2_assert_withdraw(sdp, (state != SFS_FROZEN));
912 
913 	if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags)) {
914 		gfs2_ordered_wait(sdp);
915 		log_flush_wait(sdp);
916 		op_flags = REQ_SYNC | REQ_META | REQ_PRIO;
917 	}
918 	sdp->sd_log_idle = (sdp->sd_log_flush_tail == sdp->sd_log_flush_head);
919 	gfs2_write_log_header(sdp, sdp->sd_jdesc, sdp->sd_log_sequence++,
920 			      sdp->sd_log_flush_tail, sdp->sd_log_flush_head,
921 			      flags, op_flags);
922 	gfs2_log_incr_head(sdp);
923 	log_flush_wait(sdp);
924 	log_pull_tail(sdp);
925 	gfs2_log_update_head(sdp);
926 }
927 
928 /**
929  * gfs2_ail_drain - drain the ail lists after a withdraw
930  * @sdp: Pointer to GFS2 superblock
931  */
932 void gfs2_ail_drain(struct gfs2_sbd *sdp)
933 {
934 	struct gfs2_trans *tr;
935 
936 	spin_lock(&sdp->sd_ail_lock);
937 	/*
938 	 * For transactions on the sd_ail1_list we need to drain both the
939 	 * ail1 and ail2 lists. That's because function gfs2_ail1_start_one
940 	 * (temporarily) moves items from its tr_ail1 list to tr_ail2 list
941 	 * before revokes are sent for that block. Items on the sd_ail2_list
942 	 * should have already gotten beyond that point, so no need.
943 	 */
944 	while (!list_empty(&sdp->sd_ail1_list)) {
945 		tr = list_first_entry(&sdp->sd_ail1_list, struct gfs2_trans,
946 				      tr_list);
947 		gfs2_ail_empty_tr(sdp, tr, &tr->tr_ail1_list);
948 		gfs2_ail_empty_tr(sdp, tr, &tr->tr_ail2_list);
949 		list_del(&tr->tr_list);
950 		gfs2_trans_free(sdp, tr);
951 	}
952 	while (!list_empty(&sdp->sd_ail2_list)) {
953 		tr = list_first_entry(&sdp->sd_ail2_list, struct gfs2_trans,
954 				      tr_list);
955 		gfs2_ail_empty_tr(sdp, tr, &tr->tr_ail2_list);
956 		list_del(&tr->tr_list);
957 		gfs2_trans_free(sdp, tr);
958 	}
959 	gfs2_drain_revokes(sdp);
960 	spin_unlock(&sdp->sd_ail_lock);
961 }
962 
963 /**
964  * empty_ail1_list - try to start IO and empty the ail1 list
965  * @sdp: Pointer to GFS2 superblock
966  */
967 static void empty_ail1_list(struct gfs2_sbd *sdp)
968 {
969 	unsigned long start = jiffies;
970 
971 	for (;;) {
972 		if (time_after(jiffies, start + (HZ * 600))) {
973 			fs_err(sdp, "Error: In %s for 10 minutes! t=%d\n",
974 			       __func__, current->journal_info ? 1 : 0);
975 			dump_ail_list(sdp);
976 			return;
977 		}
978 		gfs2_ail1_start(sdp);
979 		gfs2_ail1_wait(sdp);
980 		if (gfs2_ail1_empty(sdp, 0))
981 			return;
982 	}
983 }
984 
985 /**
986  * trans_drain - drain the buf and databuf queue for a failed transaction
987  * @tr: the transaction to drain
988  *
989  * When this is called, we're taking an error exit for a log write that failed
990  * but since we bypassed the after_commit functions, we need to remove the
991  * items from the buf and databuf queue.
992  */
993 static void trans_drain(struct gfs2_trans *tr)
994 {
995 	struct gfs2_bufdata *bd;
996 	struct list_head *head;
997 
998 	if (!tr)
999 		return;
1000 
1001 	head = &tr->tr_buf;
1002 	while (!list_empty(head)) {
1003 		bd = list_first_entry(head, struct gfs2_bufdata, bd_list);
1004 		list_del_init(&bd->bd_list);
1005 		if (!list_empty(&bd->bd_ail_st_list))
1006 			gfs2_remove_from_ail(bd);
1007 		kmem_cache_free(gfs2_bufdata_cachep, bd);
1008 	}
1009 	head = &tr->tr_databuf;
1010 	while (!list_empty(head)) {
1011 		bd = list_first_entry(head, struct gfs2_bufdata, bd_list);
1012 		list_del_init(&bd->bd_list);
1013 		if (!list_empty(&bd->bd_ail_st_list))
1014 			gfs2_remove_from_ail(bd);
1015 		kmem_cache_free(gfs2_bufdata_cachep, bd);
1016 	}
1017 }
1018 
1019 /**
1020  * gfs2_log_flush - flush incore transaction(s)
1021  * @sdp: The filesystem
1022  * @gl: The glock structure to flush.  If NULL, flush the whole incore log
1023  * @flags: The log header flags: GFS2_LOG_HEAD_FLUSH_* and debug flags
1024  *
1025  */
1026 
1027 void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags)
1028 {
1029 	struct gfs2_trans *tr = NULL;
1030 	unsigned int reserved_blocks = 0, used_blocks = 0;
1031 	enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);
1032 	unsigned int first_log_head;
1033 	unsigned int reserved_revokes = 0;
1034 
1035 	down_write(&sdp->sd_log_flush_lock);
1036 	trace_gfs2_log_flush(sdp, 1, flags);
1037 
1038 repeat:
1039 	/*
1040 	 * Do this check while holding the log_flush_lock to prevent new
1041 	 * buffers from being added to the ail via gfs2_pin()
1042 	 */
1043 	if (gfs2_withdrawn(sdp) || !test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
1044 		goto out;
1045 
1046 	/* Log might have been flushed while we waited for the flush lock */
1047 	if (gl && !test_bit(GLF_LFLUSH, &gl->gl_flags))
1048 		goto out;
1049 
1050 	first_log_head = sdp->sd_log_head;
1051 	sdp->sd_log_flush_head = first_log_head;
1052 
1053 	tr = sdp->sd_log_tr;
1054 	if (tr || sdp->sd_log_num_revoke) {
1055 		if (reserved_blocks)
1056 			gfs2_log_release(sdp, reserved_blocks);
1057 		reserved_blocks = sdp->sd_log_blks_reserved;
1058 		reserved_revokes = sdp->sd_log_num_revoke;
1059 		if (tr) {
1060 			sdp->sd_log_tr = NULL;
1061 			tr->tr_first = first_log_head;
1062 			if (unlikely (state == SFS_FROZEN)) {
1063 				if (gfs2_assert_withdraw_delayed(sdp,
1064 				       !tr->tr_num_buf_new && !tr->tr_num_databuf_new))
1065 					goto out_withdraw;
1066 			}
1067 		}
1068 	} else if (!reserved_blocks) {
1069 		unsigned int taboo_blocks = GFS2_LOG_FLUSH_MIN_BLOCKS;
1070 
1071 		reserved_blocks = GFS2_LOG_FLUSH_MIN_BLOCKS;
1072 		if (current == sdp->sd_logd_process)
1073 			taboo_blocks = 0;
1074 
1075 		if (!__gfs2_log_try_reserve(sdp, reserved_blocks, taboo_blocks)) {
1076 			up_write(&sdp->sd_log_flush_lock);
1077 			__gfs2_log_reserve(sdp, reserved_blocks, taboo_blocks);
1078 			down_write(&sdp->sd_log_flush_lock);
1079 			goto repeat;
1080 		}
1081 		BUG_ON(sdp->sd_log_num_revoke);
1082 	}
1083 
1084 	if (flags & GFS2_LOG_HEAD_FLUSH_SHUTDOWN)
1085 		clear_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
1086 
1087 	if (unlikely(state == SFS_FROZEN))
1088 		if (gfs2_assert_withdraw_delayed(sdp, !reserved_revokes))
1089 			goto out_withdraw;
1090 
1091 	gfs2_ordered_write(sdp);
1092 	if (gfs2_withdrawn(sdp))
1093 		goto out_withdraw;
1094 	lops_before_commit(sdp, tr);
1095 	if (gfs2_withdrawn(sdp))
1096 		goto out_withdraw;
1097 	gfs2_log_submit_bio(&sdp->sd_jdesc->jd_log_bio, REQ_OP_WRITE);
1098 	if (gfs2_withdrawn(sdp))
1099 		goto out_withdraw;
1100 
1101 	if (sdp->sd_log_head != sdp->sd_log_flush_head) {
1102 		log_write_header(sdp, flags);
1103 	} else if (sdp->sd_log_tail != sdp->sd_log_flush_tail && !sdp->sd_log_idle) {
1104 		log_write_header(sdp, flags);
1105 	}
1106 	if (gfs2_withdrawn(sdp))
1107 		goto out_withdraw;
1108 	lops_after_commit(sdp, tr);
1109 
1110 	gfs2_log_lock(sdp);
1111 	sdp->sd_log_blks_reserved = 0;
1112 
1113 	spin_lock(&sdp->sd_ail_lock);
1114 	if (tr && !list_empty(&tr->tr_ail1_list)) {
1115 		list_add(&tr->tr_list, &sdp->sd_ail1_list);
1116 		tr = NULL;
1117 	}
1118 	spin_unlock(&sdp->sd_ail_lock);
1119 	gfs2_log_unlock(sdp);
1120 
1121 	if (!(flags & GFS2_LOG_HEAD_FLUSH_NORMAL)) {
1122 		if (!sdp->sd_log_idle) {
1123 			empty_ail1_list(sdp);
1124 			if (gfs2_withdrawn(sdp))
1125 				goto out_withdraw;
1126 			log_write_header(sdp, flags);
1127 		}
1128 		if (flags & (GFS2_LOG_HEAD_FLUSH_SHUTDOWN |
1129 			     GFS2_LOG_HEAD_FLUSH_FREEZE))
1130 			gfs2_log_shutdown(sdp);
1131 		if (flags & GFS2_LOG_HEAD_FLUSH_FREEZE)
1132 			atomic_set(&sdp->sd_freeze_state, SFS_FROZEN);
1133 	}
1134 
1135 out_end:
1136 	used_blocks = log_distance(sdp, sdp->sd_log_flush_head, first_log_head);
1137 	reserved_revokes += atomic_read(&sdp->sd_log_revokes_available);
1138 	atomic_set(&sdp->sd_log_revokes_available, sdp->sd_ldptrs);
1139 	gfs2_assert_withdraw(sdp, reserved_revokes % sdp->sd_inptrs == sdp->sd_ldptrs);
1140 	if (reserved_revokes > sdp->sd_ldptrs)
1141 		reserved_blocks += (reserved_revokes - sdp->sd_ldptrs) / sdp->sd_inptrs;
1142 out:
1143 	if (used_blocks != reserved_blocks) {
1144 		gfs2_assert_withdraw_delayed(sdp, used_blocks < reserved_blocks);
1145 		gfs2_log_release(sdp, reserved_blocks - used_blocks);
1146 	}
1147 	up_write(&sdp->sd_log_flush_lock);
1148 	gfs2_trans_free(sdp, tr);
1149 	if (gfs2_withdrawing(sdp))
1150 		gfs2_withdraw(sdp);
1151 	trace_gfs2_log_flush(sdp, 0, flags);
1152 	return;
1153 
1154 out_withdraw:
1155 	trans_drain(tr);
1156 	/**
1157 	 * If the tr_list is empty, we're withdrawing during a log
1158 	 * flush that targets a transaction, but the transaction was
1159 	 * never queued onto any of the ail lists. Here we add it to
1160 	 * ail1 just so that ail_drain() will find and free it.
1161 	 */
1162 	spin_lock(&sdp->sd_ail_lock);
1163 	if (tr && list_empty(&tr->tr_list))
1164 		list_add(&tr->tr_list, &sdp->sd_ail1_list);
1165 	spin_unlock(&sdp->sd_ail_lock);
1166 	tr = NULL;
1167 	goto out_end;
1168 }
1169 
1170 /**
1171  * gfs2_merge_trans - Merge a new transaction into a cached transaction
1172  * @sdp: the filesystem
1173  * @new: New transaction to be merged
1174  */
1175 
1176 static void gfs2_merge_trans(struct gfs2_sbd *sdp, struct gfs2_trans *new)
1177 {
1178 	struct gfs2_trans *old = sdp->sd_log_tr;
1179 
1180 	WARN_ON_ONCE(!test_bit(TR_ATTACHED, &old->tr_flags));
1181 
1182 	old->tr_num_buf_new	+= new->tr_num_buf_new;
1183 	old->tr_num_databuf_new	+= new->tr_num_databuf_new;
1184 	old->tr_num_buf_rm	+= new->tr_num_buf_rm;
1185 	old->tr_num_databuf_rm	+= new->tr_num_databuf_rm;
1186 	old->tr_revokes		+= new->tr_revokes;
1187 	old->tr_num_revoke	+= new->tr_num_revoke;
1188 
1189 	list_splice_tail_init(&new->tr_databuf, &old->tr_databuf);
1190 	list_splice_tail_init(&new->tr_buf, &old->tr_buf);
1191 
1192 	spin_lock(&sdp->sd_ail_lock);
1193 	list_splice_tail_init(&new->tr_ail1_list, &old->tr_ail1_list);
1194 	list_splice_tail_init(&new->tr_ail2_list, &old->tr_ail2_list);
1195 	spin_unlock(&sdp->sd_ail_lock);
1196 }
1197 
1198 static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
1199 {
1200 	unsigned int reserved;
1201 	unsigned int unused;
1202 	unsigned int maxres;
1203 
1204 	gfs2_log_lock(sdp);
1205 
1206 	if (sdp->sd_log_tr) {
1207 		gfs2_merge_trans(sdp, tr);
1208 	} else if (tr->tr_num_buf_new || tr->tr_num_databuf_new) {
1209 		gfs2_assert_withdraw(sdp, !test_bit(TR_ONSTACK, &tr->tr_flags));
1210 		sdp->sd_log_tr = tr;
1211 		set_bit(TR_ATTACHED, &tr->tr_flags);
1212 	}
1213 
1214 	reserved = calc_reserved(sdp);
1215 	maxres = sdp->sd_log_blks_reserved + tr->tr_reserved;
1216 	gfs2_assert_withdraw(sdp, maxres >= reserved);
1217 	unused = maxres - reserved;
1218 	if (unused)
1219 		gfs2_log_release(sdp, unused);
1220 	sdp->sd_log_blks_reserved = reserved;
1221 
1222 	gfs2_log_unlock(sdp);
1223 }
1224 
1225 /**
1226  * gfs2_log_commit - Commit a transaction to the log
1227  * @sdp: the filesystem
1228  * @tr: the transaction
1229  *
1230  * We wake up gfs2_logd if the number of pinned blocks exceed thresh1
1231  * or the total number of used blocks (pinned blocks plus AIL blocks)
1232  * is greater than thresh2.
1233  *
1234  * At mount time thresh1 is 2/5ths of journal size, thresh2 is 4/5ths of
1235  * journal size.
1236  *
1237  * Returns: errno
1238  */
1239 
1240 void gfs2_log_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
1241 {
1242 	log_refund(sdp, tr);
1243 
1244 	if (atomic_read(&sdp->sd_log_pinned) > atomic_read(&sdp->sd_log_thresh1) ||
1245 	    ((sdp->sd_jdesc->jd_blocks - atomic_read(&sdp->sd_log_blks_free)) >
1246 	    atomic_read(&sdp->sd_log_thresh2)))
1247 		wake_up(&sdp->sd_logd_waitq);
1248 }
1249 
1250 /**
1251  * gfs2_log_shutdown - write a shutdown header into a journal
1252  * @sdp: the filesystem
1253  *
1254  */
1255 
1256 static void gfs2_log_shutdown(struct gfs2_sbd *sdp)
1257 {
1258 	gfs2_assert_withdraw(sdp, !sdp->sd_log_blks_reserved);
1259 	gfs2_assert_withdraw(sdp, !sdp->sd_log_num_revoke);
1260 	gfs2_assert_withdraw(sdp, list_empty(&sdp->sd_ail1_list));
1261 
1262 	log_write_header(sdp, GFS2_LOG_HEAD_UNMOUNT | GFS2_LFC_SHUTDOWN);
1263 	log_pull_tail(sdp);
1264 
1265 	gfs2_assert_warn(sdp, sdp->sd_log_head == sdp->sd_log_tail);
1266 	gfs2_assert_warn(sdp, list_empty(&sdp->sd_ail2_list));
1267 }
1268 
1269 static inline int gfs2_jrnl_flush_reqd(struct gfs2_sbd *sdp)
1270 {
1271 	return (atomic_read(&sdp->sd_log_pinned) +
1272 		atomic_read(&sdp->sd_log_blks_needed) >=
1273 		atomic_read(&sdp->sd_log_thresh1));
1274 }
1275 
1276 static inline int gfs2_ail_flush_reqd(struct gfs2_sbd *sdp)
1277 {
1278 	unsigned int used_blocks = sdp->sd_jdesc->jd_blocks - atomic_read(&sdp->sd_log_blks_free);
1279 
1280 	if (test_and_clear_bit(SDF_FORCE_AIL_FLUSH, &sdp->sd_flags))
1281 		return 1;
1282 
1283 	return used_blocks + atomic_read(&sdp->sd_log_blks_needed) >=
1284 		atomic_read(&sdp->sd_log_thresh2);
1285 }
1286 
1287 /**
1288  * gfs2_logd - Update log tail as Active Items get flushed to in-place blocks
1289  * @data: Pointer to GFS2 superblock
1290  *
1291  * Also, periodically check to make sure that we're using the most recent
1292  * journal index.
1293  */
1294 
1295 int gfs2_logd(void *data)
1296 {
1297 	struct gfs2_sbd *sdp = data;
1298 	unsigned long t = 1;
1299 	DEFINE_WAIT(wait);
1300 
1301 	while (!kthread_should_stop()) {
1302 
1303 		if (gfs2_withdrawn(sdp)) {
1304 			msleep_interruptible(HZ);
1305 			continue;
1306 		}
1307 		/* Check for errors writing to the journal */
1308 		if (sdp->sd_log_error) {
1309 			gfs2_lm(sdp,
1310 				"GFS2: fsid=%s: error %d: "
1311 				"withdrawing the file system to "
1312 				"prevent further damage.\n",
1313 				sdp->sd_fsname, sdp->sd_log_error);
1314 			gfs2_withdraw(sdp);
1315 			continue;
1316 		}
1317 
1318 		if (gfs2_jrnl_flush_reqd(sdp) || t == 0) {
1319 			gfs2_ail1_empty(sdp, 0);
1320 			gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_NORMAL |
1321 						  GFS2_LFC_LOGD_JFLUSH_REQD);
1322 		}
1323 
1324 		if (gfs2_ail_flush_reqd(sdp)) {
1325 			gfs2_ail1_start(sdp);
1326 			gfs2_ail1_wait(sdp);
1327 			gfs2_ail1_empty(sdp, 0);
1328 			gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_NORMAL |
1329 						  GFS2_LFC_LOGD_AIL_FLUSH_REQD);
1330 		}
1331 
1332 		t = gfs2_tune_get(sdp, gt_logd_secs) * HZ;
1333 
1334 		try_to_freeze();
1335 
1336 		do {
1337 			prepare_to_wait(&sdp->sd_logd_waitq, &wait,
1338 					TASK_INTERRUPTIBLE);
1339 			if (!gfs2_ail_flush_reqd(sdp) &&
1340 			    !gfs2_jrnl_flush_reqd(sdp) &&
1341 			    !kthread_should_stop())
1342 				t = schedule_timeout(t);
1343 		} while(t && !gfs2_ail_flush_reqd(sdp) &&
1344 			!gfs2_jrnl_flush_reqd(sdp) &&
1345 			!kthread_should_stop());
1346 		finish_wait(&sdp->sd_logd_waitq, &wait);
1347 	}
1348 
1349 	return 0;
1350 }
1351 
1352