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TOMOYO Linux Cross Reference
Linux/fs/nilfs2/the_nilfs.c

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  1 // SPDX-License-Identifier: GPL-2.0+
  2 /*
  3  * the_nilfs shared structure.
  4  *
  5  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
  6  *
  7  * Written by Ryusuke Konishi.
  8  *
  9  */
 10 
 11 #include <linux/buffer_head.h>
 12 #include <linux/slab.h>
 13 #include <linux/blkdev.h>
 14 #include <linux/backing-dev.h>
 15 #include <linux/random.h>
 16 #include <linux/log2.h>
 17 #include <linux/crc32.h>
 18 #include "nilfs.h"
 19 #include "segment.h"
 20 #include "alloc.h"
 21 #include "cpfile.h"
 22 #include "sufile.h"
 23 #include "dat.h"
 24 #include "segbuf.h"
 25 
 26 
 27 static int nilfs_valid_sb(struct nilfs_super_block *sbp);
 28 
 29 void nilfs_set_last_segment(struct the_nilfs *nilfs,
 30                             sector_t start_blocknr, u64 seq, __u64 cno)
 31 {
 32         spin_lock(&nilfs->ns_last_segment_lock);
 33         nilfs->ns_last_pseg = start_blocknr;
 34         nilfs->ns_last_seq = seq;
 35         nilfs->ns_last_cno = cno;
 36 
 37         if (!nilfs_sb_dirty(nilfs)) {
 38                 if (nilfs->ns_prev_seq == nilfs->ns_last_seq)
 39                         goto stay_cursor;
 40 
 41                 set_nilfs_sb_dirty(nilfs);
 42         }
 43         nilfs->ns_prev_seq = nilfs->ns_last_seq;
 44 
 45  stay_cursor:
 46         spin_unlock(&nilfs->ns_last_segment_lock);
 47 }
 48 
 49 /**
 50  * alloc_nilfs - allocate a nilfs object
 51  * @sb: super block instance
 52  *
 53  * Return Value: On success, pointer to the_nilfs is returned.
 54  * On error, NULL is returned.
 55  */
 56 struct the_nilfs *alloc_nilfs(struct super_block *sb)
 57 {
 58         struct the_nilfs *nilfs;
 59 
 60         nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
 61         if (!nilfs)
 62                 return NULL;
 63 
 64         nilfs->ns_sb = sb;
 65         nilfs->ns_bdev = sb->s_bdev;
 66         atomic_set(&nilfs->ns_ndirtyblks, 0);
 67         init_rwsem(&nilfs->ns_sem);
 68         mutex_init(&nilfs->ns_snapshot_mount_mutex);
 69         INIT_LIST_HEAD(&nilfs->ns_dirty_files);
 70         INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
 71         spin_lock_init(&nilfs->ns_inode_lock);
 72         spin_lock_init(&nilfs->ns_next_gen_lock);
 73         spin_lock_init(&nilfs->ns_last_segment_lock);
 74         nilfs->ns_cptree = RB_ROOT;
 75         spin_lock_init(&nilfs->ns_cptree_lock);
 76         init_rwsem(&nilfs->ns_segctor_sem);
 77         nilfs->ns_sb_update_freq = NILFS_SB_FREQ;
 78 
 79         return nilfs;
 80 }
 81 
 82 /**
 83  * destroy_nilfs - destroy nilfs object
 84  * @nilfs: nilfs object to be released
 85  */
 86 void destroy_nilfs(struct the_nilfs *nilfs)
 87 {
 88         might_sleep();
 89         if (nilfs_init(nilfs)) {
 90                 brelse(nilfs->ns_sbh[0]);
 91                 brelse(nilfs->ns_sbh[1]);
 92         }
 93         kfree(nilfs);
 94 }
 95 
 96 static int nilfs_load_super_root(struct the_nilfs *nilfs,
 97                                  struct super_block *sb, sector_t sr_block)
 98 {
 99         struct buffer_head *bh_sr;
100         struct nilfs_super_root *raw_sr;
101         struct nilfs_super_block **sbp = nilfs->ns_sbp;
102         struct nilfs_inode *rawi;
103         unsigned int dat_entry_size, segment_usage_size, checkpoint_size;
104         unsigned int inode_size;
105         int err;
106 
107         err = nilfs_read_super_root_block(nilfs, sr_block, &bh_sr, 1);
108         if (unlikely(err))
109                 return err;
110 
111         down_read(&nilfs->ns_sem);
112         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
113         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
114         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
115         up_read(&nilfs->ns_sem);
116 
117         inode_size = nilfs->ns_inode_size;
118 
119         rawi = (void *)bh_sr->b_data + NILFS_SR_DAT_OFFSET(inode_size);
120         err = nilfs_dat_read(sb, dat_entry_size, rawi, &nilfs->ns_dat);
121         if (err)
122                 goto failed;
123 
124         rawi = (void *)bh_sr->b_data + NILFS_SR_CPFILE_OFFSET(inode_size);
125         err = nilfs_cpfile_read(sb, checkpoint_size, rawi, &nilfs->ns_cpfile);
126         if (err)
127                 goto failed_dat;
128 
129         rawi = (void *)bh_sr->b_data + NILFS_SR_SUFILE_OFFSET(inode_size);
130         err = nilfs_sufile_read(sb, segment_usage_size, rawi,
131                                 &nilfs->ns_sufile);
132         if (err)
133                 goto failed_cpfile;
134 
135         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
136         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
137 
138  failed:
139         brelse(bh_sr);
140         return err;
141 
142  failed_cpfile:
143         iput(nilfs->ns_cpfile);
144 
145  failed_dat:
146         iput(nilfs->ns_dat);
147         goto failed;
148 }
149 
150 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
151 {
152         memset(ri, 0, sizeof(*ri));
153         INIT_LIST_HEAD(&ri->ri_used_segments);
154 }
155 
156 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
157 {
158         nilfs_dispose_segment_list(&ri->ri_used_segments);
159 }
160 
161 /**
162  * nilfs_store_log_cursor - load log cursor from a super block
163  * @nilfs: nilfs object
164  * @sbp: buffer storing super block to be read
165  *
166  * nilfs_store_log_cursor() reads the last position of the log
167  * containing a super root from a given super block, and initializes
168  * relevant information on the nilfs object preparatory for log
169  * scanning and recovery.
170  */
171 static int nilfs_store_log_cursor(struct the_nilfs *nilfs,
172                                   struct nilfs_super_block *sbp)
173 {
174         int ret = 0;
175 
176         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
177         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
178         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
179 
180         nilfs->ns_prev_seq = nilfs->ns_last_seq;
181         nilfs->ns_seg_seq = nilfs->ns_last_seq;
182         nilfs->ns_segnum =
183                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
184         nilfs->ns_cno = nilfs->ns_last_cno + 1;
185         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
186                 nilfs_err(nilfs->ns_sb,
187                           "pointed segment number is out of range: segnum=%llu, nsegments=%lu",
188                           (unsigned long long)nilfs->ns_segnum,
189                           nilfs->ns_nsegments);
190                 ret = -EINVAL;
191         }
192         return ret;
193 }
194 
195 /**
196  * nilfs_get_blocksize - get block size from raw superblock data
197  * @sb: super block instance
198  * @sbp: superblock raw data buffer
199  * @blocksize: place to store block size
200  *
201  * nilfs_get_blocksize() calculates the block size from the block size
202  * exponent information written in @sbp and stores it in @blocksize,
203  * or aborts with an error message if it's too large.
204  *
205  * Return Value: On success, 0 is returned. If the block size is too
206  * large, -EINVAL is returned.
207  */
208 static int nilfs_get_blocksize(struct super_block *sb,
209                                struct nilfs_super_block *sbp, int *blocksize)
210 {
211         unsigned int shift_bits = le32_to_cpu(sbp->s_log_block_size);
212 
213         if (unlikely(shift_bits >
214                      ilog2(NILFS_MAX_BLOCK_SIZE) - BLOCK_SIZE_BITS)) {
215                 nilfs_err(sb, "too large filesystem blocksize: 2 ^ %u KiB",
216                           shift_bits);
217                 return -EINVAL;
218         }
219         *blocksize = BLOCK_SIZE << shift_bits;
220         return 0;
221 }
222 
223 /**
224  * load_nilfs - load and recover the nilfs
225  * @nilfs: the_nilfs structure to be released
226  * @sb: super block instance used to recover past segment
227  *
228  * load_nilfs() searches and load the latest super root,
229  * attaches the last segment, and does recovery if needed.
230  * The caller must call this exclusively for simultaneous mounts.
231  */
232 int load_nilfs(struct the_nilfs *nilfs, struct super_block *sb)
233 {
234         struct nilfs_recovery_info ri;
235         unsigned int s_flags = sb->s_flags;
236         int really_read_only = bdev_read_only(nilfs->ns_bdev);
237         int valid_fs = nilfs_valid_fs(nilfs);
238         int err;
239 
240         if (!valid_fs) {
241                 nilfs_warn(sb, "mounting unchecked fs");
242                 if (s_flags & SB_RDONLY) {
243                         nilfs_info(sb,
244                                    "recovery required for readonly filesystem");
245                         nilfs_info(sb,
246                                    "write access will be enabled during recovery");
247                 }
248         }
249 
250         nilfs_init_recovery_info(&ri);
251 
252         err = nilfs_search_super_root(nilfs, &ri);
253         if (unlikely(err)) {
254                 struct nilfs_super_block **sbp = nilfs->ns_sbp;
255                 int blocksize;
256 
257                 if (err != -EINVAL)
258                         goto scan_error;
259 
260                 if (!nilfs_valid_sb(sbp[1])) {
261                         nilfs_warn(sb,
262                                    "unable to fall back to spare super block");
263                         goto scan_error;
264                 }
265                 nilfs_info(sb, "trying rollback from an earlier position");
266 
267                 /*
268                  * restore super block with its spare and reconfigure
269                  * relevant states of the nilfs object.
270                  */
271                 memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
272                 nilfs->ns_crc_seed = le32_to_cpu(sbp[0]->s_crc_seed);
273                 nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
274 
275                 /* verify consistency between two super blocks */
276                 err = nilfs_get_blocksize(sb, sbp[0], &blocksize);
277                 if (err)
278                         goto scan_error;
279 
280                 if (blocksize != nilfs->ns_blocksize) {
281                         nilfs_warn(sb,
282                                    "blocksize differs between two super blocks (%d != %d)",
283                                    blocksize, nilfs->ns_blocksize);
284                         err = -EINVAL;
285                         goto scan_error;
286                 }
287 
288                 err = nilfs_store_log_cursor(nilfs, sbp[0]);
289                 if (err)
290                         goto scan_error;
291 
292                 /* drop clean flag to allow roll-forward and recovery */
293                 nilfs->ns_mount_state &= ~NILFS_VALID_FS;
294                 valid_fs = 0;
295 
296                 err = nilfs_search_super_root(nilfs, &ri);
297                 if (err)
298                         goto scan_error;
299         }
300 
301         err = nilfs_load_super_root(nilfs, sb, ri.ri_super_root);
302         if (unlikely(err)) {
303                 nilfs_err(sb, "error %d while loading super root", err);
304                 goto failed;
305         }
306 
307         err = nilfs_sysfs_create_device_group(sb);
308         if (unlikely(err))
309                 goto sysfs_error;
310 
311         if (valid_fs)
312                 goto skip_recovery;
313 
314         if (s_flags & SB_RDONLY) {
315                 __u64 features;
316 
317                 if (nilfs_test_opt(nilfs, NORECOVERY)) {
318                         nilfs_info(sb,
319                                    "norecovery option specified, skipping roll-forward recovery");
320                         goto skip_recovery;
321                 }
322                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
323                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
324                 if (features) {
325                         nilfs_err(sb,
326                                   "couldn't proceed with recovery because of unsupported optional features (%llx)",
327                                   (unsigned long long)features);
328                         err = -EROFS;
329                         goto failed_unload;
330                 }
331                 if (really_read_only) {
332                         nilfs_err(sb,
333                                   "write access unavailable, cannot proceed");
334                         err = -EROFS;
335                         goto failed_unload;
336                 }
337                 sb->s_flags &= ~SB_RDONLY;
338         } else if (nilfs_test_opt(nilfs, NORECOVERY)) {
339                 nilfs_err(sb,
340                           "recovery cancelled because norecovery option was specified for a read/write mount");
341                 err = -EINVAL;
342                 goto failed_unload;
343         }
344 
345         err = nilfs_salvage_orphan_logs(nilfs, sb, &ri);
346         if (err)
347                 goto failed_unload;
348 
349         down_write(&nilfs->ns_sem);
350         nilfs->ns_mount_state |= NILFS_VALID_FS; /* set "clean" flag */
351         err = nilfs_cleanup_super(sb);
352         up_write(&nilfs->ns_sem);
353 
354         if (err) {
355                 nilfs_err(sb,
356                           "error %d updating super block. recovery unfinished.",
357                           err);
358                 goto failed_unload;
359         }
360         nilfs_info(sb, "recovery complete");
361 
362  skip_recovery:
363         nilfs_clear_recovery_info(&ri);
364         sb->s_flags = s_flags;
365         return 0;
366 
367  scan_error:
368         nilfs_err(sb, "error %d while searching super root", err);
369         goto failed;
370 
371  failed_unload:
372         nilfs_sysfs_delete_device_group(nilfs);
373 
374  sysfs_error:
375         iput(nilfs->ns_cpfile);
376         iput(nilfs->ns_sufile);
377         iput(nilfs->ns_dat);
378 
379  failed:
380         nilfs_clear_recovery_info(&ri);
381         sb->s_flags = s_flags;
382         return err;
383 }
384 
385 static unsigned long long nilfs_max_size(unsigned int blkbits)
386 {
387         unsigned int max_bits;
388         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
389 
390         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
391         if (max_bits < 64)
392                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
393         return res;
394 }
395 
396 /**
397  * nilfs_nrsvsegs - calculate the number of reserved segments
398  * @nilfs: nilfs object
399  * @nsegs: total number of segments
400  */
401 unsigned long nilfs_nrsvsegs(struct the_nilfs *nilfs, unsigned long nsegs)
402 {
403         return max_t(unsigned long, NILFS_MIN_NRSVSEGS,
404                      DIV_ROUND_UP(nsegs * nilfs->ns_r_segments_percentage,
405                                   100));
406 }
407 
408 /**
409  * nilfs_max_segment_count - calculate the maximum number of segments
410  * @nilfs: nilfs object
411  */
412 static u64 nilfs_max_segment_count(struct the_nilfs *nilfs)
413 {
414         u64 max_count = U64_MAX;
415 
416         max_count = div64_ul(max_count, nilfs->ns_blocks_per_segment);
417         return min_t(u64, max_count, ULONG_MAX);
418 }
419 
420 void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs)
421 {
422         nilfs->ns_nsegments = nsegs;
423         nilfs->ns_nrsvsegs = nilfs_nrsvsegs(nilfs, nsegs);
424 }
425 
426 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
427                                    struct nilfs_super_block *sbp)
428 {
429         u64 nsegments, nblocks;
430 
431         if (le32_to_cpu(sbp->s_rev_level) < NILFS_MIN_SUPP_REV) {
432                 nilfs_err(nilfs->ns_sb,
433                           "unsupported revision (superblock rev.=%d.%d, current rev.=%d.%d). Please check the version of mkfs.nilfs(2).",
434                           le32_to_cpu(sbp->s_rev_level),
435                           le16_to_cpu(sbp->s_minor_rev_level),
436                           NILFS_CURRENT_REV, NILFS_MINOR_REV);
437                 return -EINVAL;
438         }
439         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
440         if (nilfs->ns_sbsize > BLOCK_SIZE)
441                 return -EINVAL;
442 
443         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
444         if (nilfs->ns_inode_size > nilfs->ns_blocksize) {
445                 nilfs_err(nilfs->ns_sb, "too large inode size: %d bytes",
446                           nilfs->ns_inode_size);
447                 return -EINVAL;
448         } else if (nilfs->ns_inode_size < NILFS_MIN_INODE_SIZE) {
449                 nilfs_err(nilfs->ns_sb, "too small inode size: %d bytes",
450                           nilfs->ns_inode_size);
451                 return -EINVAL;
452         }
453 
454         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
455         if (nilfs->ns_first_ino < NILFS_USER_INO) {
456                 nilfs_err(nilfs->ns_sb,
457                           "too small lower limit for non-reserved inode numbers: %u",
458                           nilfs->ns_first_ino);
459                 return -EINVAL;
460         }
461 
462         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
463         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
464                 nilfs_err(nilfs->ns_sb, "too short segment: %lu blocks",
465                           nilfs->ns_blocks_per_segment);
466                 return -EINVAL;
467         }
468 
469         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
470         nilfs->ns_r_segments_percentage =
471                 le32_to_cpu(sbp->s_r_segments_percentage);
472         if (nilfs->ns_r_segments_percentage < 1 ||
473             nilfs->ns_r_segments_percentage > 99) {
474                 nilfs_err(nilfs->ns_sb,
475                           "invalid reserved segments percentage: %lu",
476                           nilfs->ns_r_segments_percentage);
477                 return -EINVAL;
478         }
479 
480         nsegments = le64_to_cpu(sbp->s_nsegments);
481         if (nsegments > nilfs_max_segment_count(nilfs)) {
482                 nilfs_err(nilfs->ns_sb,
483                           "segment count %llu exceeds upper limit (%llu segments)",
484                           (unsigned long long)nsegments,
485                           (unsigned long long)nilfs_max_segment_count(nilfs));
486                 return -EINVAL;
487         }
488 
489         nblocks = sb_bdev_nr_blocks(nilfs->ns_sb);
490         if (nblocks) {
491                 u64 min_block_count = nsegments * nilfs->ns_blocks_per_segment;
492                 /*
493                  * To avoid failing to mount early device images without a
494                  * second superblock, exclude that block count from the
495                  * "min_block_count" calculation.
496                  */
497 
498                 if (nblocks < min_block_count) {
499                         nilfs_err(nilfs->ns_sb,
500                                   "total number of segment blocks %llu exceeds device size (%llu blocks)",
501                                   (unsigned long long)min_block_count,
502                                   (unsigned long long)nblocks);
503                         return -EINVAL;
504                 }
505         }
506 
507         nilfs_set_nsegments(nilfs, nsegments);
508         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
509         return 0;
510 }
511 
512 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
513 {
514         static unsigned char sum[4];
515         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
516         size_t bytes;
517         u32 crc;
518 
519         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
520                 return 0;
521         bytes = le16_to_cpu(sbp->s_bytes);
522         if (bytes < sumoff + 4 || bytes > BLOCK_SIZE)
523                 return 0;
524         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
525                        sumoff);
526         crc = crc32_le(crc, sum, 4);
527         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
528                        bytes - sumoff - 4);
529         return crc == le32_to_cpu(sbp->s_sum);
530 }
531 
532 /**
533  * nilfs_sb2_bad_offset - check the location of the second superblock
534  * @sbp: superblock raw data buffer
535  * @offset: byte offset of second superblock calculated from device size
536  *
537  * nilfs_sb2_bad_offset() checks if the position on the second
538  * superblock is valid or not based on the filesystem parameters
539  * stored in @sbp.  If @offset points to a location within the segment
540  * area, or if the parameters themselves are not normal, it is
541  * determined to be invalid.
542  *
543  * Return Value: true if invalid, false if valid.
544  */
545 static bool nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
546 {
547         unsigned int shift_bits = le32_to_cpu(sbp->s_log_block_size);
548         u32 blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
549         u64 nsegments = le64_to_cpu(sbp->s_nsegments);
550         u64 index;
551 
552         if (blocks_per_segment < NILFS_SEG_MIN_BLOCKS ||
553             shift_bits > ilog2(NILFS_MAX_BLOCK_SIZE) - BLOCK_SIZE_BITS)
554                 return true;
555 
556         index = offset >> (shift_bits + BLOCK_SIZE_BITS);
557         do_div(index, blocks_per_segment);
558         return index < nsegments;
559 }
560 
561 static void nilfs_release_super_block(struct the_nilfs *nilfs)
562 {
563         int i;
564 
565         for (i = 0; i < 2; i++) {
566                 if (nilfs->ns_sbp[i]) {
567                         brelse(nilfs->ns_sbh[i]);
568                         nilfs->ns_sbh[i] = NULL;
569                         nilfs->ns_sbp[i] = NULL;
570                 }
571         }
572 }
573 
574 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
575 {
576         brelse(nilfs->ns_sbh[0]);
577         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
578         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
579         nilfs->ns_sbh[1] = NULL;
580         nilfs->ns_sbp[1] = NULL;
581 }
582 
583 void nilfs_swap_super_block(struct the_nilfs *nilfs)
584 {
585         struct buffer_head *tsbh = nilfs->ns_sbh[0];
586         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
587 
588         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
589         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
590         nilfs->ns_sbh[1] = tsbh;
591         nilfs->ns_sbp[1] = tsbp;
592 }
593 
594 static int nilfs_load_super_block(struct the_nilfs *nilfs,
595                                   struct super_block *sb, int blocksize,
596                                   struct nilfs_super_block **sbpp)
597 {
598         struct nilfs_super_block **sbp = nilfs->ns_sbp;
599         struct buffer_head **sbh = nilfs->ns_sbh;
600         u64 sb2off, devsize = bdev_nr_bytes(nilfs->ns_bdev);
601         int valid[2], swp = 0, older;
602 
603         if (devsize < NILFS_SEG_MIN_BLOCKS * NILFS_MIN_BLOCK_SIZE + 4096) {
604                 nilfs_err(sb, "device size too small");
605                 return -EINVAL;
606         }
607         sb2off = NILFS_SB2_OFFSET_BYTES(devsize);
608 
609         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
610                                         &sbh[0]);
611         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
612 
613         if (!sbp[0]) {
614                 if (!sbp[1]) {
615                         nilfs_err(sb, "unable to read superblock");
616                         return -EIO;
617                 }
618                 nilfs_warn(sb,
619                            "unable to read primary superblock (blocksize = %d)",
620                            blocksize);
621         } else if (!sbp[1]) {
622                 nilfs_warn(sb,
623                            "unable to read secondary superblock (blocksize = %d)",
624                            blocksize);
625         }
626 
627         /*
628          * Compare two super blocks and set 1 in swp if the secondary
629          * super block is valid and newer.  Otherwise, set 0 in swp.
630          */
631         valid[0] = nilfs_valid_sb(sbp[0]);
632         valid[1] = nilfs_valid_sb(sbp[1]);
633         swp = valid[1] && (!valid[0] ||
634                            le64_to_cpu(sbp[1]->s_last_cno) >
635                            le64_to_cpu(sbp[0]->s_last_cno));
636 
637         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
638                 brelse(sbh[1]);
639                 sbh[1] = NULL;
640                 sbp[1] = NULL;
641                 valid[1] = 0;
642                 swp = 0;
643         }
644         if (!valid[swp]) {
645                 nilfs_release_super_block(nilfs);
646                 nilfs_err(sb, "couldn't find nilfs on the device");
647                 return -EINVAL;
648         }
649 
650         if (!valid[!swp])
651                 nilfs_warn(sb,
652                            "broken superblock, retrying with spare superblock (blocksize = %d)",
653                            blocksize);
654         if (swp)
655                 nilfs_swap_super_block(nilfs);
656 
657         /*
658          * Calculate the array index of the older superblock data.
659          * If one has been dropped, set index 0 pointing to the remaining one,
660          * otherwise set index 1 pointing to the old one (including if both
661          * are the same).
662          *
663          *  Divided case             valid[0]  valid[1]  swp  ->  older
664          *  -------------------------------------------------------------
665          *  Both SBs are invalid        0         0       N/A (Error)
666          *  SB1 is invalid              0         1       1         0
667          *  SB2 is invalid              1         0       0         0
668          *  SB2 is newer                1         1       1         0
669          *  SB2 is older or the same    1         1       0         1
670          */
671         older = valid[1] ^ swp;
672 
673         nilfs->ns_sbwcount = 0;
674         nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
675         nilfs->ns_prot_seq = le64_to_cpu(sbp[older]->s_last_seq);
676         *sbpp = sbp[0];
677         return 0;
678 }
679 
680 /**
681  * init_nilfs - initialize a NILFS instance.
682  * @nilfs: the_nilfs structure
683  * @sb: super block
684  *
685  * init_nilfs() performs common initialization per block device (e.g.
686  * reading the super block, getting disk layout information, initializing
687  * shared fields in the_nilfs).
688  *
689  * Return Value: On success, 0 is returned. On error, a negative error
690  * code is returned.
691  */
692 int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb)
693 {
694         struct nilfs_super_block *sbp;
695         int blocksize;
696         int err;
697 
698         down_write(&nilfs->ns_sem);
699 
700         blocksize = sb_min_blocksize(sb, NILFS_MIN_BLOCK_SIZE);
701         if (!blocksize) {
702                 nilfs_err(sb, "unable to set blocksize");
703                 err = -EINVAL;
704                 goto out;
705         }
706         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
707         if (err)
708                 goto out;
709 
710         err = nilfs_store_magic(sb, sbp);
711         if (err)
712                 goto failed_sbh;
713 
714         err = nilfs_check_feature_compatibility(sb, sbp);
715         if (err)
716                 goto failed_sbh;
717 
718         err = nilfs_get_blocksize(sb, sbp, &blocksize);
719         if (err)
720                 goto failed_sbh;
721 
722         if (blocksize < NILFS_MIN_BLOCK_SIZE) {
723                 nilfs_err(sb,
724                           "couldn't mount because of unsupported filesystem blocksize %d",
725                           blocksize);
726                 err = -EINVAL;
727                 goto failed_sbh;
728         }
729         if (sb->s_blocksize != blocksize) {
730                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
731 
732                 if (blocksize < hw_blocksize) {
733                         nilfs_err(sb,
734                                   "blocksize %d too small for device (sector-size = %d)",
735                                   blocksize, hw_blocksize);
736                         err = -EINVAL;
737                         goto failed_sbh;
738                 }
739                 nilfs_release_super_block(nilfs);
740                 if (!sb_set_blocksize(sb, blocksize)) {
741                         nilfs_err(sb, "bad blocksize %d", blocksize);
742                         err = -EINVAL;
743                         goto out;
744                 }
745 
746                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
747                 if (err)
748                         goto out;
749                         /*
750                          * Not to failed_sbh; sbh is released automatically
751                          * when reloading fails.
752                          */
753         }
754         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
755         nilfs->ns_blocksize = blocksize;
756 
757         get_random_bytes(&nilfs->ns_next_generation,
758                          sizeof(nilfs->ns_next_generation));
759 
760         err = nilfs_store_disk_layout(nilfs, sbp);
761         if (err)
762                 goto failed_sbh;
763 
764         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
765 
766         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
767 
768         err = nilfs_store_log_cursor(nilfs, sbp);
769         if (err)
770                 goto failed_sbh;
771 
772         set_nilfs_init(nilfs);
773         err = 0;
774  out:
775         up_write(&nilfs->ns_sem);
776         return err;
777 
778  failed_sbh:
779         nilfs_release_super_block(nilfs);
780         goto out;
781 }
782 
783 int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
784                             size_t nsegs)
785 {
786         sector_t seg_start, seg_end;
787         sector_t start = 0, nblocks = 0;
788         unsigned int sects_per_block;
789         __u64 *sn;
790         int ret = 0;
791 
792         sects_per_block = (1 << nilfs->ns_blocksize_bits) /
793                 bdev_logical_block_size(nilfs->ns_bdev);
794         for (sn = segnump; sn < segnump + nsegs; sn++) {
795                 nilfs_get_segment_range(nilfs, *sn, &seg_start, &seg_end);
796 
797                 if (!nblocks) {
798                         start = seg_start;
799                         nblocks = seg_end - seg_start + 1;
800                 } else if (start + nblocks == seg_start) {
801                         nblocks += seg_end - seg_start + 1;
802                 } else {
803                         ret = blkdev_issue_discard(nilfs->ns_bdev,
804                                                    start * sects_per_block,
805                                                    nblocks * sects_per_block,
806                                                    GFP_NOFS);
807                         if (ret < 0)
808                                 return ret;
809                         nblocks = 0;
810                 }
811         }
812         if (nblocks)
813                 ret = blkdev_issue_discard(nilfs->ns_bdev,
814                                            start * sects_per_block,
815                                            nblocks * sects_per_block,
816                                            GFP_NOFS);
817         return ret;
818 }
819 
820 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
821 {
822         unsigned long ncleansegs;
823 
824         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
825         *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
826         return 0;
827 }
828 
829 int nilfs_near_disk_full(struct the_nilfs *nilfs)
830 {
831         unsigned long ncleansegs, nincsegs;
832 
833         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
834         nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
835                 nilfs->ns_blocks_per_segment + 1;
836 
837         return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
838 }
839 
840 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno)
841 {
842         struct rb_node *n;
843         struct nilfs_root *root;
844 
845         spin_lock(&nilfs->ns_cptree_lock);
846         n = nilfs->ns_cptree.rb_node;
847         while (n) {
848                 root = rb_entry(n, struct nilfs_root, rb_node);
849 
850                 if (cno < root->cno) {
851                         n = n->rb_left;
852                 } else if (cno > root->cno) {
853                         n = n->rb_right;
854                 } else {
855                         refcount_inc(&root->count);
856                         spin_unlock(&nilfs->ns_cptree_lock);
857                         return root;
858                 }
859         }
860         spin_unlock(&nilfs->ns_cptree_lock);
861 
862         return NULL;
863 }
864 
865 struct nilfs_root *
866 nilfs_find_or_create_root(struct the_nilfs *nilfs, __u64 cno)
867 {
868         struct rb_node **p, *parent;
869         struct nilfs_root *root, *new;
870         int err;
871 
872         root = nilfs_lookup_root(nilfs, cno);
873         if (root)
874                 return root;
875 
876         new = kzalloc(sizeof(*root), GFP_KERNEL);
877         if (!new)
878                 return NULL;
879 
880         spin_lock(&nilfs->ns_cptree_lock);
881 
882         p = &nilfs->ns_cptree.rb_node;
883         parent = NULL;
884 
885         while (*p) {
886                 parent = *p;
887                 root = rb_entry(parent, struct nilfs_root, rb_node);
888 
889                 if (cno < root->cno) {
890                         p = &(*p)->rb_left;
891                 } else if (cno > root->cno) {
892                         p = &(*p)->rb_right;
893                 } else {
894                         refcount_inc(&root->count);
895                         spin_unlock(&nilfs->ns_cptree_lock);
896                         kfree(new);
897                         return root;
898                 }
899         }
900 
901         new->cno = cno;
902         new->ifile = NULL;
903         new->nilfs = nilfs;
904         refcount_set(&new->count, 1);
905         atomic64_set(&new->inodes_count, 0);
906         atomic64_set(&new->blocks_count, 0);
907 
908         rb_link_node(&new->rb_node, parent, p);
909         rb_insert_color(&new->rb_node, &nilfs->ns_cptree);
910 
911         spin_unlock(&nilfs->ns_cptree_lock);
912 
913         err = nilfs_sysfs_create_snapshot_group(new);
914         if (err) {
915                 kfree(new);
916                 new = NULL;
917         }
918 
919         return new;
920 }
921 
922 void nilfs_put_root(struct nilfs_root *root)
923 {
924         struct the_nilfs *nilfs = root->nilfs;
925 
926         if (refcount_dec_and_lock(&root->count, &nilfs->ns_cptree_lock)) {
927                 rb_erase(&root->rb_node, &nilfs->ns_cptree);
928                 spin_unlock(&nilfs->ns_cptree_lock);
929 
930                 nilfs_sysfs_delete_snapshot_group(root);
931                 iput(root->ifile);
932 
933                 kfree(root);
934         }
935 }
936 

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