1 /*
2  * mdt.c - meta data file for NILFS
3  *
4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
19  *
20  * Written by Ryusuke Konishi <ryusuke@osrg.net>
21  */
22 
23 #include <linux/buffer_head.h>
24 #include <linux/mpage.h>
25 #include <linux/mm.h>
26 #include <linux/writeback.h>
27 #include <linux/backing-dev.h>
28 #include <linux/swap.h>
29 #include <linux/slab.h>
30 #include "nilfs.h"
31 #include "btnode.h"
32 #include "segment.h"
33 #include "page.h"
34 #include "mdt.h"
35 
36 
37 #define NILFS_MDT_MAX_RA_BLOCKS		(16 - 1)
38 
39 
40 static int
nilfs_mdt_insert_new_block(struct inode * inode,unsigned long block,struct buffer_head * bh,void (* init_block)(struct inode *,struct buffer_head *,void *))41 nilfs_mdt_insert_new_block(struct inode *inode, unsigned long block,
42 			   struct buffer_head *bh,
43 			   void (*init_block)(struct inode *,
44 					      struct buffer_head *, void *))
45 {
46 	struct nilfs_inode_info *ii = NILFS_I(inode);
47 	void *kaddr;
48 	int ret;
49 
50 	/* Caller exclude read accesses using page lock */
51 
52 	/* set_buffer_new(bh); */
53 	bh->b_blocknr = 0;
54 
55 	ret = nilfs_bmap_insert(ii->i_bmap, block, (unsigned long)bh);
56 	if (unlikely(ret))
57 		return ret;
58 
59 	set_buffer_mapped(bh);
60 
61 	kaddr = kmap_atomic(bh->b_page);
62 	memset(kaddr + bh_offset(bh), 0, 1 << inode->i_blkbits);
63 	if (init_block)
64 		init_block(inode, bh, kaddr);
65 	flush_dcache_page(bh->b_page);
66 	kunmap_atomic(kaddr);
67 
68 	set_buffer_uptodate(bh);
69 	mark_buffer_dirty(bh);
70 	nilfs_mdt_mark_dirty(inode);
71 	return 0;
72 }
73 
nilfs_mdt_create_block(struct inode * inode,unsigned long block,struct buffer_head ** out_bh,void (* init_block)(struct inode *,struct buffer_head *,void *))74 static int nilfs_mdt_create_block(struct inode *inode, unsigned long block,
75 				  struct buffer_head **out_bh,
76 				  void (*init_block)(struct inode *,
77 						     struct buffer_head *,
78 						     void *))
79 {
80 	struct super_block *sb = inode->i_sb;
81 	struct nilfs_transaction_info ti;
82 	struct buffer_head *bh;
83 	int err;
84 
85 	nilfs_transaction_begin(sb, &ti, 0);
86 
87 	err = -ENOMEM;
88 	bh = nilfs_grab_buffer(inode, inode->i_mapping, block, 0);
89 	if (unlikely(!bh))
90 		goto failed_unlock;
91 
92 	err = -EEXIST;
93 	if (buffer_uptodate(bh))
94 		goto failed_bh;
95 
96 	wait_on_buffer(bh);
97 	if (buffer_uptodate(bh))
98 		goto failed_bh;
99 
100 	bh->b_bdev = sb->s_bdev;
101 	err = nilfs_mdt_insert_new_block(inode, block, bh, init_block);
102 	if (likely(!err)) {
103 		get_bh(bh);
104 		*out_bh = bh;
105 	}
106 
107  failed_bh:
108 	unlock_page(bh->b_page);
109 	page_cache_release(bh->b_page);
110 	brelse(bh);
111 
112  failed_unlock:
113 	if (likely(!err))
114 		err = nilfs_transaction_commit(sb);
115 	else
116 		nilfs_transaction_abort(sb);
117 
118 	return err;
119 }
120 
121 static int
nilfs_mdt_submit_block(struct inode * inode,unsigned long blkoff,int mode,struct buffer_head ** out_bh)122 nilfs_mdt_submit_block(struct inode *inode, unsigned long blkoff,
123 		       int mode, struct buffer_head **out_bh)
124 {
125 	struct buffer_head *bh;
126 	__u64 blknum = 0;
127 	int ret = -ENOMEM;
128 
129 	bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
130 	if (unlikely(!bh))
131 		goto failed;
132 
133 	ret = -EEXIST; /* internal code */
134 	if (buffer_uptodate(bh))
135 		goto out;
136 
137 	if (mode == READA) {
138 		if (!trylock_buffer(bh)) {
139 			ret = -EBUSY;
140 			goto failed_bh;
141 		}
142 	} else /* mode == READ */
143 		lock_buffer(bh);
144 
145 	if (buffer_uptodate(bh)) {
146 		unlock_buffer(bh);
147 		goto out;
148 	}
149 
150 	ret = nilfs_bmap_lookup(NILFS_I(inode)->i_bmap, blkoff, &blknum);
151 	if (unlikely(ret)) {
152 		unlock_buffer(bh);
153 		goto failed_bh;
154 	}
155 	map_bh(bh, inode->i_sb, (sector_t)blknum);
156 
157 	bh->b_end_io = end_buffer_read_sync;
158 	get_bh(bh);
159 	submit_bh(mode, bh);
160 	ret = 0;
161  out:
162 	get_bh(bh);
163 	*out_bh = bh;
164 
165  failed_bh:
166 	unlock_page(bh->b_page);
167 	page_cache_release(bh->b_page);
168 	brelse(bh);
169  failed:
170 	return ret;
171 }
172 
nilfs_mdt_read_block(struct inode * inode,unsigned long block,int readahead,struct buffer_head ** out_bh)173 static int nilfs_mdt_read_block(struct inode *inode, unsigned long block,
174 				int readahead, struct buffer_head **out_bh)
175 {
176 	struct buffer_head *first_bh, *bh;
177 	unsigned long blkoff;
178 	int i, nr_ra_blocks = NILFS_MDT_MAX_RA_BLOCKS;
179 	int err;
180 
181 	err = nilfs_mdt_submit_block(inode, block, READ, &first_bh);
182 	if (err == -EEXIST) /* internal code */
183 		goto out;
184 
185 	if (unlikely(err))
186 		goto failed;
187 
188 	if (readahead) {
189 		blkoff = block + 1;
190 		for (i = 0; i < nr_ra_blocks; i++, blkoff++) {
191 			err = nilfs_mdt_submit_block(inode, blkoff, READA, &bh);
192 			if (likely(!err || err == -EEXIST))
193 				brelse(bh);
194 			else if (err != -EBUSY)
195 				break;
196 				/* abort readahead if bmap lookup failed */
197 			if (!buffer_locked(first_bh))
198 				goto out_no_wait;
199 		}
200 	}
201 
202 	wait_on_buffer(first_bh);
203 
204  out_no_wait:
205 	err = -EIO;
206 	if (!buffer_uptodate(first_bh))
207 		goto failed_bh;
208  out:
209 	*out_bh = first_bh;
210 	return 0;
211 
212  failed_bh:
213 	brelse(first_bh);
214  failed:
215 	return err;
216 }
217 
218 /**
219  * nilfs_mdt_get_block - read or create a buffer on meta data file.
220  * @inode: inode of the meta data file
221  * @blkoff: block offset
222  * @create: create flag
223  * @init_block: initializer used for newly allocated block
224  * @out_bh: output of a pointer to the buffer_head
225  *
226  * nilfs_mdt_get_block() looks up the specified buffer and tries to create
227  * a new buffer if @create is not zero.  On success, the returned buffer is
228  * assured to be either existing or formatted using a buffer lock on success.
229  * @out_bh is substituted only when zero is returned.
230  *
231  * Return Value: On success, it returns 0. On error, the following negative
232  * error code is returned.
233  *
234  * %-ENOMEM - Insufficient memory available.
235  *
236  * %-EIO - I/O error
237  *
238  * %-ENOENT - the specified block does not exist (hole block)
239  *
240  * %-EROFS - Read only filesystem (for create mode)
241  */
nilfs_mdt_get_block(struct inode * inode,unsigned long blkoff,int create,void (* init_block)(struct inode *,struct buffer_head *,void *),struct buffer_head ** out_bh)242 int nilfs_mdt_get_block(struct inode *inode, unsigned long blkoff, int create,
243 			void (*init_block)(struct inode *,
244 					   struct buffer_head *, void *),
245 			struct buffer_head **out_bh)
246 {
247 	int ret;
248 
249 	/* Should be rewritten with merging nilfs_mdt_read_block() */
250  retry:
251 	ret = nilfs_mdt_read_block(inode, blkoff, !create, out_bh);
252 	if (!create || ret != -ENOENT)
253 		return ret;
254 
255 	ret = nilfs_mdt_create_block(inode, blkoff, out_bh, init_block);
256 	if (unlikely(ret == -EEXIST)) {
257 		/* create = 0; */  /* limit read-create loop retries */
258 		goto retry;
259 	}
260 	return ret;
261 }
262 
263 /**
264  * nilfs_mdt_delete_block - make a hole on the meta data file.
265  * @inode: inode of the meta data file
266  * @block: block offset
267  *
268  * Return Value: On success, zero is returned.
269  * On error, one of the following negative error code is returned.
270  *
271  * %-ENOMEM - Insufficient memory available.
272  *
273  * %-EIO - I/O error
274  */
nilfs_mdt_delete_block(struct inode * inode,unsigned long block)275 int nilfs_mdt_delete_block(struct inode *inode, unsigned long block)
276 {
277 	struct nilfs_inode_info *ii = NILFS_I(inode);
278 	int err;
279 
280 	err = nilfs_bmap_delete(ii->i_bmap, block);
281 	if (!err || err == -ENOENT) {
282 		nilfs_mdt_mark_dirty(inode);
283 		nilfs_mdt_forget_block(inode, block);
284 	}
285 	return err;
286 }
287 
288 /**
289  * nilfs_mdt_forget_block - discard dirty state and try to remove the page
290  * @inode: inode of the meta data file
291  * @block: block offset
292  *
293  * nilfs_mdt_forget_block() clears a dirty flag of the specified buffer, and
294  * tries to release the page including the buffer from a page cache.
295  *
296  * Return Value: On success, 0 is returned. On error, one of the following
297  * negative error code is returned.
298  *
299  * %-EBUSY - page has an active buffer.
300  *
301  * %-ENOENT - page cache has no page addressed by the offset.
302  */
nilfs_mdt_forget_block(struct inode * inode,unsigned long block)303 int nilfs_mdt_forget_block(struct inode *inode, unsigned long block)
304 {
305 	pgoff_t index = (pgoff_t)block >>
306 		(PAGE_CACHE_SHIFT - inode->i_blkbits);
307 	struct page *page;
308 	unsigned long first_block;
309 	int ret = 0;
310 	int still_dirty;
311 
312 	page = find_lock_page(inode->i_mapping, index);
313 	if (!page)
314 		return -ENOENT;
315 
316 	wait_on_page_writeback(page);
317 
318 	first_block = (unsigned long)index <<
319 		(PAGE_CACHE_SHIFT - inode->i_blkbits);
320 	if (page_has_buffers(page)) {
321 		struct buffer_head *bh;
322 
323 		bh = nilfs_page_get_nth_block(page, block - first_block);
324 		nilfs_forget_buffer(bh);
325 	}
326 	still_dirty = PageDirty(page);
327 	unlock_page(page);
328 	page_cache_release(page);
329 
330 	if (still_dirty ||
331 	    invalidate_inode_pages2_range(inode->i_mapping, index, index) != 0)
332 		ret = -EBUSY;
333 	return ret;
334 }
335 
336 /**
337  * nilfs_mdt_mark_block_dirty - mark a block on the meta data file dirty.
338  * @inode: inode of the meta data file
339  * @block: block offset
340  *
341  * Return Value: On success, it returns 0. On error, the following negative
342  * error code is returned.
343  *
344  * %-ENOMEM - Insufficient memory available.
345  *
346  * %-EIO - I/O error
347  *
348  * %-ENOENT - the specified block does not exist (hole block)
349  */
nilfs_mdt_mark_block_dirty(struct inode * inode,unsigned long block)350 int nilfs_mdt_mark_block_dirty(struct inode *inode, unsigned long block)
351 {
352 	struct buffer_head *bh;
353 	int err;
354 
355 	err = nilfs_mdt_read_block(inode, block, 0, &bh);
356 	if (unlikely(err))
357 		return err;
358 	mark_buffer_dirty(bh);
359 	nilfs_mdt_mark_dirty(inode);
360 	brelse(bh);
361 	return 0;
362 }
363 
nilfs_mdt_fetch_dirty(struct inode * inode)364 int nilfs_mdt_fetch_dirty(struct inode *inode)
365 {
366 	struct nilfs_inode_info *ii = NILFS_I(inode);
367 
368 	if (nilfs_bmap_test_and_clear_dirty(ii->i_bmap)) {
369 		set_bit(NILFS_I_DIRTY, &ii->i_state);
370 		return 1;
371 	}
372 	return test_bit(NILFS_I_DIRTY, &ii->i_state);
373 }
374 
375 static int
nilfs_mdt_write_page(struct page * page,struct writeback_control * wbc)376 nilfs_mdt_write_page(struct page *page, struct writeback_control *wbc)
377 {
378 	struct inode *inode;
379 	struct super_block *sb;
380 	int err = 0;
381 
382 	redirty_page_for_writepage(wbc, page);
383 	unlock_page(page);
384 
385 	inode = page->mapping->host;
386 	if (!inode)
387 		return 0;
388 
389 	sb = inode->i_sb;
390 
391 	if (wbc->sync_mode == WB_SYNC_ALL)
392 		err = nilfs_construct_segment(sb);
393 	else if (wbc->for_reclaim)
394 		nilfs_flush_segment(sb, inode->i_ino);
395 
396 	return err;
397 }
398 
399 
400 static const struct address_space_operations def_mdt_aops = {
401 	.writepage		= nilfs_mdt_write_page,
402 };
403 
404 static const struct inode_operations def_mdt_iops;
405 static const struct file_operations def_mdt_fops;
406 
407 
nilfs_mdt_init(struct inode * inode,gfp_t gfp_mask,size_t objsz)408 int nilfs_mdt_init(struct inode *inode, gfp_t gfp_mask, size_t objsz)
409 {
410 	struct nilfs_mdt_info *mi;
411 
412 	mi = kzalloc(max(sizeof(*mi), objsz), GFP_NOFS);
413 	if (!mi)
414 		return -ENOMEM;
415 
416 	init_rwsem(&mi->mi_sem);
417 	inode->i_private = mi;
418 
419 	inode->i_mode = S_IFREG;
420 	mapping_set_gfp_mask(inode->i_mapping, gfp_mask);
421 	inode->i_mapping->backing_dev_info = inode->i_sb->s_bdi;
422 
423 	inode->i_op = &def_mdt_iops;
424 	inode->i_fop = &def_mdt_fops;
425 	inode->i_mapping->a_ops = &def_mdt_aops;
426 
427 	return 0;
428 }
429 
nilfs_mdt_set_entry_size(struct inode * inode,unsigned entry_size,unsigned header_size)430 void nilfs_mdt_set_entry_size(struct inode *inode, unsigned entry_size,
431 			      unsigned header_size)
432 {
433 	struct nilfs_mdt_info *mi = NILFS_MDT(inode);
434 
435 	mi->mi_entry_size = entry_size;
436 	mi->mi_entries_per_block = (1 << inode->i_blkbits) / entry_size;
437 	mi->mi_first_entry_offset = DIV_ROUND_UP(header_size, entry_size);
438 }
439 
440 /**
441  * nilfs_mdt_setup_shadow_map - setup shadow map and bind it to metadata file
442  * @inode: inode of the metadata file
443  * @shadow: shadow mapping
444  */
nilfs_mdt_setup_shadow_map(struct inode * inode,struct nilfs_shadow_map * shadow)445 int nilfs_mdt_setup_shadow_map(struct inode *inode,
446 			       struct nilfs_shadow_map *shadow)
447 {
448 	struct nilfs_mdt_info *mi = NILFS_MDT(inode);
449 	struct backing_dev_info *bdi = inode->i_sb->s_bdi;
450 
451 	INIT_LIST_HEAD(&shadow->frozen_buffers);
452 	address_space_init_once(&shadow->frozen_data);
453 	nilfs_mapping_init(&shadow->frozen_data, inode, bdi);
454 	address_space_init_once(&shadow->frozen_btnodes);
455 	nilfs_mapping_init(&shadow->frozen_btnodes, inode, bdi);
456 	mi->mi_shadow = shadow;
457 	return 0;
458 }
459 
460 /**
461  * nilfs_mdt_save_to_shadow_map - copy bmap and dirty pages to shadow map
462  * @inode: inode of the metadata file
463  */
nilfs_mdt_save_to_shadow_map(struct inode * inode)464 int nilfs_mdt_save_to_shadow_map(struct inode *inode)
465 {
466 	struct nilfs_mdt_info *mi = NILFS_MDT(inode);
467 	struct nilfs_inode_info *ii = NILFS_I(inode);
468 	struct nilfs_shadow_map *shadow = mi->mi_shadow;
469 	int ret;
470 
471 	ret = nilfs_copy_dirty_pages(&shadow->frozen_data, inode->i_mapping);
472 	if (ret)
473 		goto out;
474 
475 	ret = nilfs_copy_dirty_pages(&shadow->frozen_btnodes,
476 				     &ii->i_btnode_cache);
477 	if (ret)
478 		goto out;
479 
480 	nilfs_bmap_save(ii->i_bmap, &shadow->bmap_store);
481  out:
482 	return ret;
483 }
484 
nilfs_mdt_freeze_buffer(struct inode * inode,struct buffer_head * bh)485 int nilfs_mdt_freeze_buffer(struct inode *inode, struct buffer_head *bh)
486 {
487 	struct nilfs_shadow_map *shadow = NILFS_MDT(inode)->mi_shadow;
488 	struct buffer_head *bh_frozen;
489 	struct page *page;
490 	int blkbits = inode->i_blkbits;
491 
492 	page = grab_cache_page(&shadow->frozen_data, bh->b_page->index);
493 	if (!page)
494 		return -ENOMEM;
495 
496 	if (!page_has_buffers(page))
497 		create_empty_buffers(page, 1 << blkbits, 0);
498 
499 	bh_frozen = nilfs_page_get_nth_block(page, bh_offset(bh) >> blkbits);
500 
501 	if (!buffer_uptodate(bh_frozen))
502 		nilfs_copy_buffer(bh_frozen, bh);
503 	if (list_empty(&bh_frozen->b_assoc_buffers)) {
504 		list_add_tail(&bh_frozen->b_assoc_buffers,
505 			      &shadow->frozen_buffers);
506 		set_buffer_nilfs_redirected(bh);
507 	} else {
508 		brelse(bh_frozen); /* already frozen */
509 	}
510 
511 	unlock_page(page);
512 	page_cache_release(page);
513 	return 0;
514 }
515 
516 struct buffer_head *
nilfs_mdt_get_frozen_buffer(struct inode * inode,struct buffer_head * bh)517 nilfs_mdt_get_frozen_buffer(struct inode *inode, struct buffer_head *bh)
518 {
519 	struct nilfs_shadow_map *shadow = NILFS_MDT(inode)->mi_shadow;
520 	struct buffer_head *bh_frozen = NULL;
521 	struct page *page;
522 	int n;
523 
524 	page = find_lock_page(&shadow->frozen_data, bh->b_page->index);
525 	if (page) {
526 		if (page_has_buffers(page)) {
527 			n = bh_offset(bh) >> inode->i_blkbits;
528 			bh_frozen = nilfs_page_get_nth_block(page, n);
529 		}
530 		unlock_page(page);
531 		page_cache_release(page);
532 	}
533 	return bh_frozen;
534 }
535 
nilfs_release_frozen_buffers(struct nilfs_shadow_map * shadow)536 static void nilfs_release_frozen_buffers(struct nilfs_shadow_map *shadow)
537 {
538 	struct list_head *head = &shadow->frozen_buffers;
539 	struct buffer_head *bh;
540 
541 	while (!list_empty(head)) {
542 		bh = list_first_entry(head, struct buffer_head,
543 				      b_assoc_buffers);
544 		list_del_init(&bh->b_assoc_buffers);
545 		brelse(bh); /* drop ref-count to make it releasable */
546 	}
547 }
548 
549 /**
550  * nilfs_mdt_restore_from_shadow_map - restore dirty pages and bmap state
551  * @inode: inode of the metadata file
552  */
nilfs_mdt_restore_from_shadow_map(struct inode * inode)553 void nilfs_mdt_restore_from_shadow_map(struct inode *inode)
554 {
555 	struct nilfs_mdt_info *mi = NILFS_MDT(inode);
556 	struct nilfs_inode_info *ii = NILFS_I(inode);
557 	struct nilfs_shadow_map *shadow = mi->mi_shadow;
558 
559 	down_write(&mi->mi_sem);
560 
561 	if (mi->mi_palloc_cache)
562 		nilfs_palloc_clear_cache(inode);
563 
564 	nilfs_clear_dirty_pages(inode->i_mapping);
565 	nilfs_copy_back_pages(inode->i_mapping, &shadow->frozen_data);
566 
567 	nilfs_clear_dirty_pages(&ii->i_btnode_cache);
568 	nilfs_copy_back_pages(&ii->i_btnode_cache, &shadow->frozen_btnodes);
569 
570 	nilfs_bmap_restore(ii->i_bmap, &shadow->bmap_store);
571 
572 	up_write(&mi->mi_sem);
573 }
574 
575 /**
576  * nilfs_mdt_clear_shadow_map - truncate pages in shadow map caches
577  * @inode: inode of the metadata file
578  */
nilfs_mdt_clear_shadow_map(struct inode * inode)579 void nilfs_mdt_clear_shadow_map(struct inode *inode)
580 {
581 	struct nilfs_mdt_info *mi = NILFS_MDT(inode);
582 	struct nilfs_shadow_map *shadow = mi->mi_shadow;
583 
584 	down_write(&mi->mi_sem);
585 	nilfs_release_frozen_buffers(shadow);
586 	truncate_inode_pages(&shadow->frozen_data, 0);
587 	truncate_inode_pages(&shadow->frozen_btnodes, 0);
588 	up_write(&mi->mi_sem);
589 }
590