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1 /*
2 * fs/logfs/super.c
3 *
4 * As should be obvious for Linux kernel code, license is GPLv2
5 *
6 * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
7 *
8 * Generally contains mount/umount code and also serves as a dump area for
9 * any functions that don't fit elsewhere and neither justify a file of their
10 * own.
11 */
12 #include "logfs.h"
13 #include <linux/bio.h>
14 #include <linux/slab.h>
15 #include <linux/blkdev.h>
16 #include <linux/module.h>
17 #include <linux/mtd/mtd.h>
18 #include <linux/statfs.h>
19 #include <linux/buffer_head.h>
20
21 static DEFINE_MUTEX(emergency_mutex);
22 static struct page *emergency_page;
23
24 struct page *emergency_read_begin(struct address_space *mapping, pgoff_t index)
25 {
26 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
27 struct page *page;
28 int err;
29
30 page = read_cache_page(mapping, index, filler, NULL);
31 if (page)
32 return page;
33
34 /* No more pages available, switch to emergency page */
35 printk(KERN_INFO"Logfs: Using emergency page\n");
36 mutex_lock(&emergency_mutex);
37 err = filler(NULL, emergency_page);
38 if (err) {
39 mutex_unlock(&emergency_mutex);
40 printk(KERN_EMERG"Logfs: Error reading emergency page\n");
41 return ERR_PTR(err);
42 }
43 return emergency_page;
44 }
45
46 void emergency_read_end(struct page *page)
47 {
48 if (page == emergency_page)
49 mutex_unlock(&emergency_mutex);
50 else
51 page_cache_release(page);
52 }
53
54 static void dump_segfile(struct super_block *sb)
55 {
56 struct logfs_super *super = logfs_super(sb);
57 struct logfs_segment_entry se;
58 u32 segno;
59
60 for (segno = 0; segno < super->s_no_segs; segno++) {
61 logfs_get_segment_entry(sb, segno, &se);
62 printk("%3x: %6x %8x", segno, be32_to_cpu(se.ec_level),
63 be32_to_cpu(se.valid));
64 if (++segno < super->s_no_segs) {
65 logfs_get_segment_entry(sb, segno, &se);
66 printk(" %6x %8x", be32_to_cpu(se.ec_level),
67 be32_to_cpu(se.valid));
68 }
69 if (++segno < super->s_no_segs) {
70 logfs_get_segment_entry(sb, segno, &se);
71 printk(" %6x %8x", be32_to_cpu(se.ec_level),
72 be32_to_cpu(se.valid));
73 }
74 if (++segno < super->s_no_segs) {
75 logfs_get_segment_entry(sb, segno, &se);
76 printk(" %6x %8x", be32_to_cpu(se.ec_level),
77 be32_to_cpu(se.valid));
78 }
79 printk("\n");
80 }
81 }
82
83 /*
84 * logfs_crash_dump - dump debug information to device
85 *
86 * The LogFS superblock only occupies part of a segment. This function will
87 * write as much debug information as it can gather into the spare space.
88 */
89 void logfs_crash_dump(struct super_block *sb)
90 {
91 dump_segfile(sb);
92 }
93
94 /*
95 * FIXME: There should be a reserve for root, similar to ext2.
96 */
97 int logfs_statfs(struct dentry *dentry, struct kstatfs *stats)
98 {
99 struct super_block *sb = dentry->d_sb;
100 struct logfs_super *super = logfs_super(sb);
101
102 stats->f_type = LOGFS_MAGIC_U32;
103 stats->f_bsize = sb->s_blocksize;
104 stats->f_blocks = super->s_size >> LOGFS_BLOCK_BITS >> 3;
105 stats->f_bfree = super->s_free_bytes >> sb->s_blocksize_bits;
106 stats->f_bavail = super->s_free_bytes >> sb->s_blocksize_bits;
107 stats->f_files = 0;
108 stats->f_ffree = 0;
109 stats->f_namelen = LOGFS_MAX_NAMELEN;
110 return 0;
111 }
112
113 static int logfs_sb_set(struct super_block *sb, void *_super)
114 {
115 struct logfs_super *super = _super;
116
117 sb->s_fs_info = super;
118 sb->s_mtd = super->s_mtd;
119 sb->s_bdev = super->s_bdev;
120 #ifdef CONFIG_BLOCK
121 if (sb->s_bdev)
122 sb->s_bdi = &bdev_get_queue(sb->s_bdev)->backing_dev_info;
123 #endif
124 #ifdef CONFIG_MTD
125 if (sb->s_mtd)
126 sb->s_bdi = sb->s_mtd->backing_dev_info;
127 #endif
128 return 0;
129 }
130
131 static int logfs_sb_test(struct super_block *sb, void *_super)
132 {
133 struct logfs_super *super = _super;
134 struct mtd_info *mtd = super->s_mtd;
135
136 if (mtd && sb->s_mtd == mtd)
137 return 1;
138 if (super->s_bdev && sb->s_bdev == super->s_bdev)
139 return 1;
140 return 0;
141 }
142
143 static void set_segment_header(struct logfs_segment_header *sh, u8 type,
144 u8 level, u32 segno, u32 ec)
145 {
146 sh->pad = 0;
147 sh->type = type;
148 sh->level = level;
149 sh->segno = cpu_to_be32(segno);
150 sh->ec = cpu_to_be32(ec);
151 sh->gec = cpu_to_be64(segno);
152 sh->crc = logfs_crc32(sh, LOGFS_SEGMENT_HEADERSIZE, 4);
153 }
154
155 static void logfs_write_ds(struct super_block *sb, struct logfs_disk_super *ds,
156 u32 segno, u32 ec)
157 {
158 struct logfs_super *super = logfs_super(sb);
159 struct logfs_segment_header *sh = &ds->ds_sh;
160 int i;
161
162 memset(ds, 0, sizeof(*ds));
163 set_segment_header(sh, SEG_SUPER, 0, segno, ec);
164
165 ds->ds_ifile_levels = super->s_ifile_levels;
166 ds->ds_iblock_levels = super->s_iblock_levels;
167 ds->ds_data_levels = super->s_data_levels; /* XXX: Remove */
168 ds->ds_segment_shift = super->s_segshift;
169 ds->ds_block_shift = sb->s_blocksize_bits;
170 ds->ds_write_shift = super->s_writeshift;
171 ds->ds_filesystem_size = cpu_to_be64(super->s_size);
172 ds->ds_segment_size = cpu_to_be32(super->s_segsize);
173 ds->ds_bad_seg_reserve = cpu_to_be32(super->s_bad_seg_reserve);
174 ds->ds_feature_incompat = cpu_to_be64(super->s_feature_incompat);
175 ds->ds_feature_ro_compat= cpu_to_be64(super->s_feature_ro_compat);
176 ds->ds_feature_compat = cpu_to_be64(super->s_feature_compat);
177 ds->ds_feature_flags = cpu_to_be64(super->s_feature_flags);
178 ds->ds_root_reserve = cpu_to_be64(super->s_root_reserve);
179 ds->ds_speed_reserve = cpu_to_be64(super->s_speed_reserve);
180 journal_for_each(i)
181 ds->ds_journal_seg[i] = cpu_to_be32(super->s_journal_seg[i]);
182 ds->ds_magic = cpu_to_be64(LOGFS_MAGIC);
183 ds->ds_crc = logfs_crc32(ds, sizeof(*ds),
184 LOGFS_SEGMENT_HEADERSIZE + 12);
185 }
186
187 static int write_one_sb(struct super_block *sb,
188 struct page *(*find_sb)(struct super_block *sb, u64 *ofs))
189 {
190 struct logfs_super *super = logfs_super(sb);
191 struct logfs_disk_super *ds;
192 struct logfs_segment_entry se;
193 struct page *page;
194 u64 ofs;
195 u32 ec, segno;
196 int err;
197
198 page = find_sb(sb, &ofs);
199 if (!page)
200 return -EIO;
201 ds = page_address(page);
202 segno = seg_no(sb, ofs);
203 logfs_get_segment_entry(sb, segno, &se);
204 ec = be32_to_cpu(se.ec_level) >> 4;
205 ec++;
206 logfs_set_segment_erased(sb, segno, ec, 0);
207 logfs_write_ds(sb, ds, segno, ec);
208 err = super->s_devops->write_sb(sb, page);
209 page_cache_release(page);
210 return err;
211 }
212
213 int logfs_write_sb(struct super_block *sb)
214 {
215 struct logfs_super *super = logfs_super(sb);
216 int err;
217
218 /* First superblock */
219 err = write_one_sb(sb, super->s_devops->find_first_sb);
220 if (err)
221 return err;
222
223 /* Last superblock */
224 err = write_one_sb(sb, super->s_devops->find_last_sb);
225 if (err)
226 return err;
227 return 0;
228 }
229
230 static int ds_cmp(const void *ds0, const void *ds1)
231 {
232 size_t len = sizeof(struct logfs_disk_super);
233
234 /* We know the segment headers differ, so ignore them */
235 len -= LOGFS_SEGMENT_HEADERSIZE;
236 ds0 += LOGFS_SEGMENT_HEADERSIZE;
237 ds1 += LOGFS_SEGMENT_HEADERSIZE;
238 return memcmp(ds0, ds1, len);
239 }
240
241 static int logfs_recover_sb(struct super_block *sb)
242 {
243 struct logfs_super *super = logfs_super(sb);
244 struct logfs_disk_super _ds0, *ds0 = &_ds0;
245 struct logfs_disk_super _ds1, *ds1 = &_ds1;
246 int err, valid0, valid1;
247
248 /* read first superblock */
249 err = wbuf_read(sb, super->s_sb_ofs[0], sizeof(*ds0), ds0);
250 if (err)
251 return err;
252 /* read last superblock */
253 err = wbuf_read(sb, super->s_sb_ofs[1], sizeof(*ds1), ds1);
254 if (err)
255 return err;
256 valid0 = logfs_check_ds(ds0) == 0;
257 valid1 = logfs_check_ds(ds1) == 0;
258
259 if (!valid0 && valid1) {
260 printk(KERN_INFO"First superblock is invalid - fixing.\n");
261 return write_one_sb(sb, super->s_devops->find_first_sb);
262 }
263 if (valid0 && !valid1) {
264 printk(KERN_INFO"Last superblock is invalid - fixing.\n");
265 return write_one_sb(sb, super->s_devops->find_last_sb);
266 }
267 if (valid0 && valid1 && ds_cmp(ds0, ds1)) {
268 printk(KERN_INFO"Superblocks don't match - fixing.\n");
269 return logfs_write_sb(sb);
270 }
271 /* If neither is valid now, something's wrong. Didn't we properly
272 * check them before?!? */
273 BUG_ON(!valid0 && !valid1);
274 return 0;
275 }
276
277 static int logfs_make_writeable(struct super_block *sb)
278 {
279 int err;
280
281 err = logfs_open_segfile(sb);
282 if (err)
283 return err;
284
285 /* Repair any broken superblock copies */
286 err = logfs_recover_sb(sb);
287 if (err)
288 return err;
289
290 /* Check areas for trailing unaccounted data */
291 err = logfs_check_areas(sb);
292 if (err)
293 return err;
294
295 /* Do one GC pass before any data gets dirtied */
296 logfs_gc_pass(sb);
297
298 /* after all initializations are done, replay the journal
299 * for rw-mounts, if necessary */
300 err = logfs_replay_journal(sb);
301 if (err)
302 return err;
303
304 return 0;
305 }
306
307 static int logfs_get_sb_final(struct super_block *sb)
308 {
309 struct logfs_super *super = logfs_super(sb);
310 struct inode *rootdir;
311 int err;
312
313 /* root dir */
314 rootdir = logfs_iget(sb, LOGFS_INO_ROOT);
315 if (IS_ERR(rootdir))
316 goto fail;
317
318 sb->s_root = d_make_root(rootdir);
319 if (!sb->s_root)
320 goto fail;
321
322 /* at that point we know that ->put_super() will be called */
323 super->s_erase_page = alloc_pages(GFP_KERNEL, 0);
324 if (!super->s_erase_page)
325 return -ENOMEM;
326 memset(page_address(super->s_erase_page), 0xFF, PAGE_SIZE);
327
328 /* FIXME: check for read-only mounts */
329 err = logfs_make_writeable(sb);
330 if (err) {
331 __free_page(super->s_erase_page);
332 return err;
333 }
334
335 log_super("LogFS: Finished mounting\n");
336 return 0;
337
338 fail:
339 iput(super->s_master_inode);
340 iput(super->s_segfile_inode);
341 iput(super->s_mapping_inode);
342 return -EIO;
343 }
344
345 int logfs_check_ds(struct logfs_disk_super *ds)
346 {
347 struct logfs_segment_header *sh = &ds->ds_sh;
348
349 if (ds->ds_magic != cpu_to_be64(LOGFS_MAGIC))
350 return -EINVAL;
351 if (sh->crc != logfs_crc32(sh, LOGFS_SEGMENT_HEADERSIZE, 4))
352 return -EINVAL;
353 if (ds->ds_crc != logfs_crc32(ds, sizeof(*ds),
354 LOGFS_SEGMENT_HEADERSIZE + 12))
355 return -EINVAL;
356 return 0;
357 }
358
359 static struct page *find_super_block(struct super_block *sb)
360 {
361 struct logfs_super *super = logfs_super(sb);
362 struct page *first, *last;
363
364 first = super->s_devops->find_first_sb(sb, &super->s_sb_ofs[0]);
365 if (!first || IS_ERR(first))
366 return NULL;
367 last = super->s_devops->find_last_sb(sb, &super->s_sb_ofs[1]);
368 if (!last || IS_ERR(last)) {
369 page_cache_release(first);
370 return NULL;
371 }
372
373 if (!logfs_check_ds(page_address(first))) {
374 page_cache_release(last);
375 return first;
376 }
377
378 /* First one didn't work, try the second superblock */
379 if (!logfs_check_ds(page_address(last))) {
380 page_cache_release(first);
381 return last;
382 }
383
384 /* Neither worked, sorry folks */
385 page_cache_release(first);
386 page_cache_release(last);
387 return NULL;
388 }
389
390 static int __logfs_read_sb(struct super_block *sb)
391 {
392 struct logfs_super *super = logfs_super(sb);
393 struct page *page;
394 struct logfs_disk_super *ds;
395 int i;
396
397 page = find_super_block(sb);
398 if (!page)
399 return -EINVAL;
400
401 ds = page_address(page);
402 super->s_size = be64_to_cpu(ds->ds_filesystem_size);
403 super->s_root_reserve = be64_to_cpu(ds->ds_root_reserve);
404 super->s_speed_reserve = be64_to_cpu(ds->ds_speed_reserve);
405 super->s_bad_seg_reserve = be32_to_cpu(ds->ds_bad_seg_reserve);
406 super->s_segsize = 1 << ds->ds_segment_shift;
407 super->s_segmask = (1 << ds->ds_segment_shift) - 1;
408 super->s_segshift = ds->ds_segment_shift;
409 sb->s_blocksize = 1 << ds->ds_block_shift;
410 sb->s_blocksize_bits = ds->ds_block_shift;
411 super->s_writesize = 1 << ds->ds_write_shift;
412 super->s_writeshift = ds->ds_write_shift;
413 super->s_no_segs = super->s_size >> super->s_segshift;
414 super->s_no_blocks = super->s_segsize >> sb->s_blocksize_bits;
415 super->s_feature_incompat = be64_to_cpu(ds->ds_feature_incompat);
416 super->s_feature_ro_compat = be64_to_cpu(ds->ds_feature_ro_compat);
417 super->s_feature_compat = be64_to_cpu(ds->ds_feature_compat);
418 super->s_feature_flags = be64_to_cpu(ds->ds_feature_flags);
419
420 journal_for_each(i)
421 super->s_journal_seg[i] = be32_to_cpu(ds->ds_journal_seg[i]);
422
423 super->s_ifile_levels = ds->ds_ifile_levels;
424 super->s_iblock_levels = ds->ds_iblock_levels;
425 super->s_data_levels = ds->ds_data_levels;
426 super->s_total_levels = super->s_ifile_levels + super->s_iblock_levels
427 + super->s_data_levels;
428 page_cache_release(page);
429 return 0;
430 }
431
432 static int logfs_read_sb(struct super_block *sb, int read_only)
433 {
434 struct logfs_super *super = logfs_super(sb);
435 int ret;
436
437 super->s_btree_pool = mempool_create(32, btree_alloc, btree_free, NULL);
438 if (!super->s_btree_pool)
439 return -ENOMEM;
440
441 btree_init_mempool64(&super->s_shadow_tree.new, super->s_btree_pool);
442 btree_init_mempool64(&super->s_shadow_tree.old, super->s_btree_pool);
443 btree_init_mempool32(&super->s_shadow_tree.segment_map,
444 super->s_btree_pool);
445
446 ret = logfs_init_mapping(sb);
447 if (ret)
448 return ret;
449
450 ret = __logfs_read_sb(sb);
451 if (ret)
452 return ret;
453
454 if (super->s_feature_incompat & ~LOGFS_FEATURES_INCOMPAT)
455 return -EIO;
456 if ((super->s_feature_ro_compat & ~LOGFS_FEATURES_RO_COMPAT) &&
457 !read_only)
458 return -EIO;
459
460 ret = logfs_init_rw(sb);
461 if (ret)
462 return ret;
463
464 ret = logfs_init_areas(sb);
465 if (ret)
466 return ret;
467
468 ret = logfs_init_gc(sb);
469 if (ret)
470 return ret;
471
472 ret = logfs_init_journal(sb);
473 if (ret)
474 return ret;
475
476 return 0;
477 }
478
479 static void logfs_kill_sb(struct super_block *sb)
480 {
481 struct logfs_super *super = logfs_super(sb);
482
483 log_super("LogFS: Start unmounting\n");
484 /* Alias entries slow down mount, so evict as many as possible */
485 sync_filesystem(sb);
486 logfs_write_anchor(sb);
487 free_areas(sb);
488
489 /*
490 * From this point on alias entries are simply dropped - and any
491 * writes to the object store are considered bugs.
492 */
493 log_super("LogFS: Now in shutdown\n");
494 generic_shutdown_super(sb);
495 super->s_flags |= LOGFS_SB_FLAG_SHUTDOWN;
496
497 BUG_ON(super->s_dirty_used_bytes || super->s_dirty_free_bytes);
498
499 logfs_cleanup_gc(sb);
500 logfs_cleanup_journal(sb);
501 logfs_cleanup_areas(sb);
502 logfs_cleanup_rw(sb);
503 if (super->s_erase_page)
504 __free_page(super->s_erase_page);
505 super->s_devops->put_device(super);
506 logfs_mempool_destroy(super->s_btree_pool);
507 logfs_mempool_destroy(super->s_alias_pool);
508 kfree(super);
509 log_super("LogFS: Finished unmounting\n");
510 }
511
512 static struct dentry *logfs_get_sb_device(struct logfs_super *super,
513 struct file_system_type *type, int flags)
514 {
515 struct super_block *sb;
516 int err = -ENOMEM;
517 static int mount_count;
518
519 log_super("LogFS: Start mount %x\n", mount_count++);
520
521 err = -EINVAL;
522 sb = sget(type, logfs_sb_test, logfs_sb_set, flags | MS_NOATIME, super);
523 if (IS_ERR(sb)) {
524 super->s_devops->put_device(super);
525 kfree(super);
526 return ERR_CAST(sb);
527 }
528
529 if (sb->s_root) {
530 /* Device is already in use */
531 super->s_devops->put_device(super);
532 kfree(super);
533 return dget(sb->s_root);
534 }
535
536 /*
537 * sb->s_maxbytes is limited to 8TB. On 32bit systems, the page cache
538 * only covers 16TB and the upper 8TB are used for indirect blocks.
539 * On 64bit system we could bump up the limit, but that would make
540 * the filesystem incompatible with 32bit systems.
541 */
542 sb->s_maxbytes = (1ull << 43) - 1;
543 sb->s_max_links = LOGFS_LINK_MAX;
544 sb->s_op = &logfs_super_operations;
545
546 err = logfs_read_sb(sb, sb->s_flags & MS_RDONLY);
547 if (err)
548 goto err1;
549
550 sb->s_flags |= MS_ACTIVE;
551 err = logfs_get_sb_final(sb);
552 if (err) {
553 deactivate_locked_super(sb);
554 return ERR_PTR(err);
555 }
556 return dget(sb->s_root);
557
558 err1:
559 /* no ->s_root, no ->put_super() */
560 iput(super->s_master_inode);
561 iput(super->s_segfile_inode);
562 iput(super->s_mapping_inode);
563 deactivate_locked_super(sb);
564 return ERR_PTR(err);
565 }
566
567 static struct dentry *logfs_mount(struct file_system_type *type, int flags,
568 const char *devname, void *data)
569 {
570 ulong mtdnr;
571 struct logfs_super *super;
572 int err;
573
574 super = kzalloc(sizeof(*super), GFP_KERNEL);
575 if (!super)
576 return ERR_PTR(-ENOMEM);
577
578 mutex_init(&super->s_dirop_mutex);
579 mutex_init(&super->s_object_alias_mutex);
580 INIT_LIST_HEAD(&super->s_freeing_list);
581
582 if (!devname)
583 err = logfs_get_sb_bdev(super, type, devname);
584 else if (strncmp(devname, "mtd", 3))
585 err = logfs_get_sb_bdev(super, type, devname);
586 else {
587 char *garbage;
588 mtdnr = simple_strtoul(devname+3, &garbage, 0);
589 if (*garbage)
590 err = -EINVAL;
591 else
592 err = logfs_get_sb_mtd(super, mtdnr);
593 }
594
595 if (err) {
596 kfree(super);
597 return ERR_PTR(err);
598 }
599
600 return logfs_get_sb_device(super, type, flags);
601 }
602
603 static struct file_system_type logfs_fs_type = {
604 .owner = THIS_MODULE,
605 .name = "logfs",
606 .mount = logfs_mount,
607 .kill_sb = logfs_kill_sb,
608 .fs_flags = FS_REQUIRES_DEV,
609
610 };
611 MODULE_ALIAS_FS("logfs");
612
613 static int __init logfs_init(void)
614 {
615 int ret;
616
617 emergency_page = alloc_pages(GFP_KERNEL, 0);
618 if (!emergency_page)
619 return -ENOMEM;
620
621 ret = logfs_compr_init();
622 if (ret)
623 goto out1;
624
625 ret = logfs_init_inode_cache();
626 if (ret)
627 goto out2;
628
629 ret = register_filesystem(&logfs_fs_type);
630 if (!ret)
631 return 0;
632 logfs_destroy_inode_cache();
633 out2:
634 logfs_compr_exit();
635 out1:
636 __free_pages(emergency_page, 0);
637 return ret;
638 }
639
640 static void __exit logfs_exit(void)
641 {
642 unregister_filesystem(&logfs_fs_type);
643 logfs_destroy_inode_cache();
644 logfs_compr_exit();
645 __free_pages(emergency_page, 0);
646 }
647
648 module_init(logfs_init);
649 module_exit(logfs_exit);
650
651 MODULE_LICENSE("GPL v2");
652 MODULE_AUTHOR("Joern Engel <joern@logfs.org>");
653 MODULE_DESCRIPTION("scalable flash filesystem");