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Linux/fs/ntfs/logfile.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  * logfile.c - NTFS kernel journal handling. Part of the Linux-NTFS project.
  4  *
  5  * Copyright (c) 2002-2007 Anton Altaparmakov
  6  */
  7 
  8 #ifdef NTFS_RW
  9 
 10 #include <linux/types.h>
 11 #include <linux/fs.h>
 12 #include <linux/highmem.h>
 13 #include <linux/buffer_head.h>
 14 #include <linux/bitops.h>
 15 #include <linux/log2.h>
 16 #include <linux/bio.h>
 17 
 18 #include "attrib.h"
 19 #include "aops.h"
 20 #include "debug.h"
 21 #include "logfile.h"
 22 #include "malloc.h"
 23 #include "volume.h"
 24 #include "ntfs.h"
 25 
 26 /**
 27  * ntfs_check_restart_page_header - check the page header for consistency
 28  * @vi:         $LogFile inode to which the restart page header belongs
 29  * @rp:         restart page header to check
 30  * @pos:        position in @vi at which the restart page header resides
 31  *
 32  * Check the restart page header @rp for consistency and return 'true' if it is
 33  * consistent and 'false' otherwise.
 34  *
 35  * This function only needs NTFS_BLOCK_SIZE bytes in @rp, i.e. it does not
 36  * require the full restart page.
 37  */
 38 static bool ntfs_check_restart_page_header(struct inode *vi,
 39                 RESTART_PAGE_HEADER *rp, s64 pos)
 40 {
 41         u32 logfile_system_page_size, logfile_log_page_size;
 42         u16 ra_ofs, usa_count, usa_ofs, usa_end = 0;
 43         bool have_usa = true;
 44 
 45         ntfs_debug("Entering.");
 46         /*
 47          * If the system or log page sizes are smaller than the ntfs block size
 48          * or either is not a power of 2 we cannot handle this log file.
 49          */
 50         logfile_system_page_size = le32_to_cpu(rp->system_page_size);
 51         logfile_log_page_size = le32_to_cpu(rp->log_page_size);
 52         if (logfile_system_page_size < NTFS_BLOCK_SIZE ||
 53                         logfile_log_page_size < NTFS_BLOCK_SIZE ||
 54                         logfile_system_page_size &
 55                         (logfile_system_page_size - 1) ||
 56                         !is_power_of_2(logfile_log_page_size)) {
 57                 ntfs_error(vi->i_sb, "$LogFile uses unsupported page size.");
 58                 return false;
 59         }
 60         /*
 61          * We must be either at !pos (1st restart page) or at pos = system page
 62          * size (2nd restart page).
 63          */
 64         if (pos && pos != logfile_system_page_size) {
 65                 ntfs_error(vi->i_sb, "Found restart area in incorrect "
 66                                 "position in $LogFile.");
 67                 return false;
 68         }
 69         /* We only know how to handle version 1.1. */
 70         if (sle16_to_cpu(rp->major_ver) != 1 ||
 71                         sle16_to_cpu(rp->minor_ver) != 1) {
 72                 ntfs_error(vi->i_sb, "$LogFile version %i.%i is not "
 73                                 "supported.  (This driver supports version "
 74                                 "1.1 only.)", (int)sle16_to_cpu(rp->major_ver),
 75                                 (int)sle16_to_cpu(rp->minor_ver));
 76                 return false;
 77         }
 78         /*
 79          * If chkdsk has been run the restart page may not be protected by an
 80          * update sequence array.
 81          */
 82         if (ntfs_is_chkd_record(rp->magic) && !le16_to_cpu(rp->usa_count)) {
 83                 have_usa = false;
 84                 goto skip_usa_checks;
 85         }
 86         /* Verify the size of the update sequence array. */
 87         usa_count = 1 + (logfile_system_page_size >> NTFS_BLOCK_SIZE_BITS);
 88         if (usa_count != le16_to_cpu(rp->usa_count)) {
 89                 ntfs_error(vi->i_sb, "$LogFile restart page specifies "
 90                                 "inconsistent update sequence array count.");
 91                 return false;
 92         }
 93         /* Verify the position of the update sequence array. */
 94         usa_ofs = le16_to_cpu(rp->usa_ofs);
 95         usa_end = usa_ofs + usa_count * sizeof(u16);
 96         if (usa_ofs < sizeof(RESTART_PAGE_HEADER) ||
 97                         usa_end > NTFS_BLOCK_SIZE - sizeof(u16)) {
 98                 ntfs_error(vi->i_sb, "$LogFile restart page specifies "
 99                                 "inconsistent update sequence array offset.");
100                 return false;
101         }
102 skip_usa_checks:
103         /*
104          * Verify the position of the restart area.  It must be:
105          *      - aligned to 8-byte boundary,
106          *      - after the update sequence array, and
107          *      - within the system page size.
108          */
109         ra_ofs = le16_to_cpu(rp->restart_area_offset);
110         if (ra_ofs & 7 || (have_usa ? ra_ofs < usa_end :
111                         ra_ofs < sizeof(RESTART_PAGE_HEADER)) ||
112                         ra_ofs > logfile_system_page_size) {
113                 ntfs_error(vi->i_sb, "$LogFile restart page specifies "
114                                 "inconsistent restart area offset.");
115                 return false;
116         }
117         /*
118          * Only restart pages modified by chkdsk are allowed to have chkdsk_lsn
119          * set.
120          */
121         if (!ntfs_is_chkd_record(rp->magic) && sle64_to_cpu(rp->chkdsk_lsn)) {
122                 ntfs_error(vi->i_sb, "$LogFile restart page is not modified "
123                                 "by chkdsk but a chkdsk LSN is specified.");
124                 return false;
125         }
126         ntfs_debug("Done.");
127         return true;
128 }
129 
130 /**
131  * ntfs_check_restart_area - check the restart area for consistency
132  * @vi:         $LogFile inode to which the restart page belongs
133  * @rp:         restart page whose restart area to check
134  *
135  * Check the restart area of the restart page @rp for consistency and return
136  * 'true' if it is consistent and 'false' otherwise.
137  *
138  * This function assumes that the restart page header has already been
139  * consistency checked.
140  *
141  * This function only needs NTFS_BLOCK_SIZE bytes in @rp, i.e. it does not
142  * require the full restart page.
143  */
144 static bool ntfs_check_restart_area(struct inode *vi, RESTART_PAGE_HEADER *rp)
145 {
146         u64 file_size;
147         RESTART_AREA *ra;
148         u16 ra_ofs, ra_len, ca_ofs;
149         u8 fs_bits;
150 
151         ntfs_debug("Entering.");
152         ra_ofs = le16_to_cpu(rp->restart_area_offset);
153         ra = (RESTART_AREA*)((u8*)rp + ra_ofs);
154         /*
155          * Everything before ra->file_size must be before the first word
156          * protected by an update sequence number.  This ensures that it is
157          * safe to access ra->client_array_offset.
158          */
159         if (ra_ofs + offsetof(RESTART_AREA, file_size) >
160                         NTFS_BLOCK_SIZE - sizeof(u16)) {
161                 ntfs_error(vi->i_sb, "$LogFile restart area specifies "
162                                 "inconsistent file offset.");
163                 return false;
164         }
165         /*
166          * Now that we can access ra->client_array_offset, make sure everything
167          * up to the log client array is before the first word protected by an
168          * update sequence number.  This ensures we can access all of the
169          * restart area elements safely.  Also, the client array offset must be
170          * aligned to an 8-byte boundary.
171          */
172         ca_ofs = le16_to_cpu(ra->client_array_offset);
173         if (((ca_ofs + 7) & ~7) != ca_ofs ||
174                         ra_ofs + ca_ofs > NTFS_BLOCK_SIZE - sizeof(u16)) {
175                 ntfs_error(vi->i_sb, "$LogFile restart area specifies "
176                                 "inconsistent client array offset.");
177                 return false;
178         }
179         /*
180          * The restart area must end within the system page size both when
181          * calculated manually and as specified by ra->restart_area_length.
182          * Also, the calculated length must not exceed the specified length.
183          */
184         ra_len = ca_ofs + le16_to_cpu(ra->log_clients) *
185                         sizeof(LOG_CLIENT_RECORD);
186         if (ra_ofs + ra_len > le32_to_cpu(rp->system_page_size) ||
187                         ra_ofs + le16_to_cpu(ra->restart_area_length) >
188                         le32_to_cpu(rp->system_page_size) ||
189                         ra_len > le16_to_cpu(ra->restart_area_length)) {
190                 ntfs_error(vi->i_sb, "$LogFile restart area is out of bounds "
191                                 "of the system page size specified by the "
192                                 "restart page header and/or the specified "
193                                 "restart area length is inconsistent.");
194                 return false;
195         }
196         /*
197          * The ra->client_free_list and ra->client_in_use_list must be either
198          * LOGFILE_NO_CLIENT or less than ra->log_clients or they are
199          * overflowing the client array.
200          */
201         if ((ra->client_free_list != LOGFILE_NO_CLIENT &&
202                         le16_to_cpu(ra->client_free_list) >=
203                         le16_to_cpu(ra->log_clients)) ||
204                         (ra->client_in_use_list != LOGFILE_NO_CLIENT &&
205                         le16_to_cpu(ra->client_in_use_list) >=
206                         le16_to_cpu(ra->log_clients))) {
207                 ntfs_error(vi->i_sb, "$LogFile restart area specifies "
208                                 "overflowing client free and/or in use lists.");
209                 return false;
210         }
211         /*
212          * Check ra->seq_number_bits against ra->file_size for consistency.
213          * We cannot just use ffs() because the file size is not a power of 2.
214          */
215         file_size = (u64)sle64_to_cpu(ra->file_size);
216         fs_bits = 0;
217         while (file_size) {
218                 file_size >>= 1;
219                 fs_bits++;
220         }
221         if (le32_to_cpu(ra->seq_number_bits) != 67 - fs_bits) {
222                 ntfs_error(vi->i_sb, "$LogFile restart area specifies "
223                                 "inconsistent sequence number bits.");
224                 return false;
225         }
226         /* The log record header length must be a multiple of 8. */
227         if (((le16_to_cpu(ra->log_record_header_length) + 7) & ~7) !=
228                         le16_to_cpu(ra->log_record_header_length)) {
229                 ntfs_error(vi->i_sb, "$LogFile restart area specifies "
230                                 "inconsistent log record header length.");
231                 return false;
232         }
233         /* Dito for the log page data offset. */
234         if (((le16_to_cpu(ra->log_page_data_offset) + 7) & ~7) !=
235                         le16_to_cpu(ra->log_page_data_offset)) {
236                 ntfs_error(vi->i_sb, "$LogFile restart area specifies "
237                                 "inconsistent log page data offset.");
238                 return false;
239         }
240         ntfs_debug("Done.");
241         return true;
242 }
243 
244 /**
245  * ntfs_check_log_client_array - check the log client array for consistency
246  * @vi:         $LogFile inode to which the restart page belongs
247  * @rp:         restart page whose log client array to check
248  *
249  * Check the log client array of the restart page @rp for consistency and
250  * return 'true' if it is consistent and 'false' otherwise.
251  *
252  * This function assumes that the restart page header and the restart area have
253  * already been consistency checked.
254  *
255  * Unlike ntfs_check_restart_page_header() and ntfs_check_restart_area(), this
256  * function needs @rp->system_page_size bytes in @rp, i.e. it requires the full
257  * restart page and the page must be multi sector transfer deprotected.
258  */
259 static bool ntfs_check_log_client_array(struct inode *vi,
260                 RESTART_PAGE_HEADER *rp)
261 {
262         RESTART_AREA *ra;
263         LOG_CLIENT_RECORD *ca, *cr;
264         u16 nr_clients, idx;
265         bool in_free_list, idx_is_first;
266 
267         ntfs_debug("Entering.");
268         ra = (RESTART_AREA*)((u8*)rp + le16_to_cpu(rp->restart_area_offset));
269         ca = (LOG_CLIENT_RECORD*)((u8*)ra +
270                         le16_to_cpu(ra->client_array_offset));
271         /*
272          * Check the ra->client_free_list first and then check the
273          * ra->client_in_use_list.  Check each of the log client records in
274          * each of the lists and check that the array does not overflow the
275          * ra->log_clients value.  Also keep track of the number of records
276          * visited as there cannot be more than ra->log_clients records and
277          * that way we detect eventual loops in within a list.
278          */
279         nr_clients = le16_to_cpu(ra->log_clients);
280         idx = le16_to_cpu(ra->client_free_list);
281         in_free_list = true;
282 check_list:
283         for (idx_is_first = true; idx != LOGFILE_NO_CLIENT_CPU; nr_clients--,
284                         idx = le16_to_cpu(cr->next_client)) {
285                 if (!nr_clients || idx >= le16_to_cpu(ra->log_clients))
286                         goto err_out;
287                 /* Set @cr to the current log client record. */
288                 cr = ca + idx;
289                 /* The first log client record must not have a prev_client. */
290                 if (idx_is_first) {
291                         if (cr->prev_client != LOGFILE_NO_CLIENT)
292                                 goto err_out;
293                         idx_is_first = false;
294                 }
295         }
296         /* Switch to and check the in use list if we just did the free list. */
297         if (in_free_list) {
298                 in_free_list = false;
299                 idx = le16_to_cpu(ra->client_in_use_list);
300                 goto check_list;
301         }
302         ntfs_debug("Done.");
303         return true;
304 err_out:
305         ntfs_error(vi->i_sb, "$LogFile log client array is corrupt.");
306         return false;
307 }
308 
309 /**
310  * ntfs_check_and_load_restart_page - check the restart page for consistency
311  * @vi:         $LogFile inode to which the restart page belongs
312  * @rp:         restart page to check
313  * @pos:        position in @vi at which the restart page resides
314  * @wrp:        [OUT] copy of the multi sector transfer deprotected restart page
315  * @lsn:        [OUT] set to the current logfile lsn on success
316  *
317  * Check the restart page @rp for consistency and return 0 if it is consistent
318  * and -errno otherwise.  The restart page may have been modified by chkdsk in
319  * which case its magic is CHKD instead of RSTR.
320  *
321  * This function only needs NTFS_BLOCK_SIZE bytes in @rp, i.e. it does not
322  * require the full restart page.
323  *
324  * If @wrp is not NULL, on success, *@wrp will point to a buffer containing a
325  * copy of the complete multi sector transfer deprotected page.  On failure,
326  * *@wrp is undefined.
327  *
328  * Simillarly, if @lsn is not NULL, on success *@lsn will be set to the current
329  * logfile lsn according to this restart page.  On failure, *@lsn is undefined.
330  *
331  * The following error codes are defined:
332  *      -EINVAL - The restart page is inconsistent.
333  *      -ENOMEM - Not enough memory to load the restart page.
334  *      -EIO    - Failed to reading from $LogFile.
335  */
336 static int ntfs_check_and_load_restart_page(struct inode *vi,
337                 RESTART_PAGE_HEADER *rp, s64 pos, RESTART_PAGE_HEADER **wrp,
338                 LSN *lsn)
339 {
340         RESTART_AREA *ra;
341         RESTART_PAGE_HEADER *trp;
342         int size, err;
343 
344         ntfs_debug("Entering.");
345         /* Check the restart page header for consistency. */
346         if (!ntfs_check_restart_page_header(vi, rp, pos)) {
347                 /* Error output already done inside the function. */
348                 return -EINVAL;
349         }
350         /* Check the restart area for consistency. */
351         if (!ntfs_check_restart_area(vi, rp)) {
352                 /* Error output already done inside the function. */
353                 return -EINVAL;
354         }
355         ra = (RESTART_AREA*)((u8*)rp + le16_to_cpu(rp->restart_area_offset));
356         /*
357          * Allocate a buffer to store the whole restart page so we can multi
358          * sector transfer deprotect it.
359          */
360         trp = ntfs_malloc_nofs(le32_to_cpu(rp->system_page_size));
361         if (!trp) {
362                 ntfs_error(vi->i_sb, "Failed to allocate memory for $LogFile "
363                                 "restart page buffer.");
364                 return -ENOMEM;
365         }
366         /*
367          * Read the whole of the restart page into the buffer.  If it fits
368          * completely inside @rp, just copy it from there.  Otherwise map all
369          * the required pages and copy the data from them.
370          */
371         size = PAGE_SIZE - (pos & ~PAGE_MASK);
372         if (size >= le32_to_cpu(rp->system_page_size)) {
373                 memcpy(trp, rp, le32_to_cpu(rp->system_page_size));
374         } else {
375                 pgoff_t idx;
376                 struct page *page;
377                 int have_read, to_read;
378 
379                 /* First copy what we already have in @rp. */
380                 memcpy(trp, rp, size);
381                 /* Copy the remaining data one page at a time. */
382                 have_read = size;
383                 to_read = le32_to_cpu(rp->system_page_size) - size;
384                 idx = (pos + size) >> PAGE_SHIFT;
385                 BUG_ON((pos + size) & ~PAGE_MASK);
386                 do {
387                         page = ntfs_map_page(vi->i_mapping, idx);
388                         if (IS_ERR(page)) {
389                                 ntfs_error(vi->i_sb, "Error mapping $LogFile "
390                                                 "page (index %lu).", idx);
391                                 err = PTR_ERR(page);
392                                 if (err != -EIO && err != -ENOMEM)
393                                         err = -EIO;
394                                 goto err_out;
395                         }
396                         size = min_t(int, to_read, PAGE_SIZE);
397                         memcpy((u8*)trp + have_read, page_address(page), size);
398                         ntfs_unmap_page(page);
399                         have_read += size;
400                         to_read -= size;
401                         idx++;
402                 } while (to_read > 0);
403         }
404         /*
405          * Perform the multi sector transfer deprotection on the buffer if the
406          * restart page is protected.
407          */
408         if ((!ntfs_is_chkd_record(trp->magic) || le16_to_cpu(trp->usa_count))
409                         && post_read_mst_fixup((NTFS_RECORD*)trp,
410                         le32_to_cpu(rp->system_page_size))) {
411                 /*
412                  * A multi sector tranfer error was detected.  We only need to
413                  * abort if the restart page contents exceed the multi sector
414                  * transfer fixup of the first sector.
415                  */
416                 if (le16_to_cpu(rp->restart_area_offset) +
417                                 le16_to_cpu(ra->restart_area_length) >
418                                 NTFS_BLOCK_SIZE - sizeof(u16)) {
419                         ntfs_error(vi->i_sb, "Multi sector transfer error "
420                                         "detected in $LogFile restart page.");
421                         err = -EINVAL;
422                         goto err_out;
423                 }
424         }
425         /*
426          * If the restart page is modified by chkdsk or there are no active
427          * logfile clients, the logfile is consistent.  Otherwise, need to
428          * check the log client records for consistency, too.
429          */
430         err = 0;
431         if (ntfs_is_rstr_record(rp->magic) &&
432                         ra->client_in_use_list != LOGFILE_NO_CLIENT) {
433                 if (!ntfs_check_log_client_array(vi, trp)) {
434                         err = -EINVAL;
435                         goto err_out;
436                 }
437         }
438         if (lsn) {
439                 if (ntfs_is_rstr_record(rp->magic))
440                         *lsn = sle64_to_cpu(ra->current_lsn);
441                 else /* if (ntfs_is_chkd_record(rp->magic)) */
442                         *lsn = sle64_to_cpu(rp->chkdsk_lsn);
443         }
444         ntfs_debug("Done.");
445         if (wrp)
446                 *wrp = trp;
447         else {
448 err_out:
449                 ntfs_free(trp);
450         }
451         return err;
452 }
453 
454 /**
455  * ntfs_check_logfile - check the journal for consistency
456  * @log_vi:     struct inode of loaded journal $LogFile to check
457  * @rp:         [OUT] on success this is a copy of the current restart page
458  *
459  * Check the $LogFile journal for consistency and return 'true' if it is
460  * consistent and 'false' if not.  On success, the current restart page is
461  * returned in *@rp.  Caller must call ntfs_free(*@rp) when finished with it.
462  *
463  * At present we only check the two restart pages and ignore the log record
464  * pages.
465  *
466  * Note that the MstProtected flag is not set on the $LogFile inode and hence
467  * when reading pages they are not deprotected.  This is because we do not know
468  * if the $LogFile was created on a system with a different page size to ours
469  * yet and mst deprotection would fail if our page size is smaller.
470  */
471 bool ntfs_check_logfile(struct inode *log_vi, RESTART_PAGE_HEADER **rp)
472 {
473         s64 size, pos;
474         LSN rstr1_lsn, rstr2_lsn;
475         ntfs_volume *vol = NTFS_SB(log_vi->i_sb);
476         struct address_space *mapping = log_vi->i_mapping;
477         struct page *page = NULL;
478         u8 *kaddr = NULL;
479         RESTART_PAGE_HEADER *rstr1_ph = NULL;
480         RESTART_PAGE_HEADER *rstr2_ph = NULL;
481         int log_page_size, log_page_mask, err;
482         bool logfile_is_empty = true;
483         u8 log_page_bits;
484 
485         ntfs_debug("Entering.");
486         /* An empty $LogFile must have been clean before it got emptied. */
487         if (NVolLogFileEmpty(vol))
488                 goto is_empty;
489         size = i_size_read(log_vi);
490         /* Make sure the file doesn't exceed the maximum allowed size. */
491         if (size > MaxLogFileSize)
492                 size = MaxLogFileSize;
493         /*
494          * Truncate size to a multiple of the page cache size or the default
495          * log page size if the page cache size is between the default log page
496          * log page size if the page cache size is between the default log page
497          * size and twice that.
498          */
499         if (PAGE_SIZE >= DefaultLogPageSize && PAGE_SIZE <=
500                         DefaultLogPageSize * 2)
501                 log_page_size = DefaultLogPageSize;
502         else
503                 log_page_size = PAGE_SIZE;
504         log_page_mask = log_page_size - 1;
505         /*
506          * Use ntfs_ffs() instead of ffs() to enable the compiler to
507          * optimize log_page_size and log_page_bits into constants.
508          */
509         log_page_bits = ntfs_ffs(log_page_size) - 1;
510         size &= ~(s64)(log_page_size - 1);
511         /*
512          * Ensure the log file is big enough to store at least the two restart
513          * pages and the minimum number of log record pages.
514          */
515         if (size < log_page_size * 2 || (size - log_page_size * 2) >>
516                         log_page_bits < MinLogRecordPages) {
517                 ntfs_error(vol->sb, "$LogFile is too small.");
518                 return false;
519         }
520         /*
521          * Read through the file looking for a restart page.  Since the restart
522          * page header is at the beginning of a page we only need to search at
523          * what could be the beginning of a page (for each page size) rather
524          * than scanning the whole file byte by byte.  If all potential places
525          * contain empty and uninitialzed records, the log file can be assumed
526          * to be empty.
527          */
528         for (pos = 0; pos < size; pos <<= 1) {
529                 pgoff_t idx = pos >> PAGE_SHIFT;
530                 if (!page || page->index != idx) {
531                         if (page)
532                                 ntfs_unmap_page(page);
533                         page = ntfs_map_page(mapping, idx);
534                         if (IS_ERR(page)) {
535                                 ntfs_error(vol->sb, "Error mapping $LogFile "
536                                                 "page (index %lu).", idx);
537                                 goto err_out;
538                         }
539                 }
540                 kaddr = (u8*)page_address(page) + (pos & ~PAGE_MASK);
541                 /*
542                  * A non-empty block means the logfile is not empty while an
543                  * empty block after a non-empty block has been encountered
544                  * means we are done.
545                  */
546                 if (!ntfs_is_empty_recordp((le32*)kaddr))
547                         logfile_is_empty = false;
548                 else if (!logfile_is_empty)
549                         break;
550                 /*
551                  * A log record page means there cannot be a restart page after
552                  * this so no need to continue searching.
553                  */
554                 if (ntfs_is_rcrd_recordp((le32*)kaddr))
555                         break;
556                 /* If not a (modified by chkdsk) restart page, continue. */
557                 if (!ntfs_is_rstr_recordp((le32*)kaddr) &&
558                                 !ntfs_is_chkd_recordp((le32*)kaddr)) {
559                         if (!pos)
560                                 pos = NTFS_BLOCK_SIZE >> 1;
561                         continue;
562                 }
563                 /*
564                  * Check the (modified by chkdsk) restart page for consistency
565                  * and get a copy of the complete multi sector transfer
566                  * deprotected restart page.
567                  */
568                 err = ntfs_check_and_load_restart_page(log_vi,
569                                 (RESTART_PAGE_HEADER*)kaddr, pos,
570                                 !rstr1_ph ? &rstr1_ph : &rstr2_ph,
571                                 !rstr1_ph ? &rstr1_lsn : &rstr2_lsn);
572                 if (!err) {
573                         /*
574                          * If we have now found the first (modified by chkdsk)
575                          * restart page, continue looking for the second one.
576                          */
577                         if (!pos) {
578                                 pos = NTFS_BLOCK_SIZE >> 1;
579                                 continue;
580                         }
581                         /*
582                          * We have now found the second (modified by chkdsk)
583                          * restart page, so we can stop looking.
584                          */
585                         break;
586                 }
587                 /*
588                  * Error output already done inside the function.  Note, we do
589                  * not abort if the restart page was invalid as we might still
590                  * find a valid one further in the file.
591                  */
592                 if (err != -EINVAL) {
593                         ntfs_unmap_page(page);
594                         goto err_out;
595                 }
596                 /* Continue looking. */
597                 if (!pos)
598                         pos = NTFS_BLOCK_SIZE >> 1;
599         }
600         if (page)
601                 ntfs_unmap_page(page);
602         if (logfile_is_empty) {
603                 NVolSetLogFileEmpty(vol);
604 is_empty:
605                 ntfs_debug("Done.  ($LogFile is empty.)");
606                 return true;
607         }
608         if (!rstr1_ph) {
609                 BUG_ON(rstr2_ph);
610                 ntfs_error(vol->sb, "Did not find any restart pages in "
611                                 "$LogFile and it was not empty.");
612                 return false;
613         }
614         /* If both restart pages were found, use the more recent one. */
615         if (rstr2_ph) {
616                 /*
617                  * If the second restart area is more recent, switch to it.
618                  * Otherwise just throw it away.
619                  */
620                 if (rstr2_lsn > rstr1_lsn) {
621                         ntfs_debug("Using second restart page as it is more "
622                                         "recent.");
623                         ntfs_free(rstr1_ph);
624                         rstr1_ph = rstr2_ph;
625                         /* rstr1_lsn = rstr2_lsn; */
626                 } else {
627                         ntfs_debug("Using first restart page as it is more "
628                                         "recent.");
629                         ntfs_free(rstr2_ph);
630                 }
631                 rstr2_ph = NULL;
632         }
633         /* All consistency checks passed. */
634         if (rp)
635                 *rp = rstr1_ph;
636         else
637                 ntfs_free(rstr1_ph);
638         ntfs_debug("Done.");
639         return true;
640 err_out:
641         if (rstr1_ph)
642                 ntfs_free(rstr1_ph);
643         return false;
644 }
645 
646 /**
647  * ntfs_is_logfile_clean - check in the journal if the volume is clean
648  * @log_vi:     struct inode of loaded journal $LogFile to check
649  * @rp:         copy of the current restart page
650  *
651  * Analyze the $LogFile journal and return 'true' if it indicates the volume was
652  * shutdown cleanly and 'false' if not.
653  *
654  * At present we only look at the two restart pages and ignore the log record
655  * pages.  This is a little bit crude in that there will be a very small number
656  * of cases where we think that a volume is dirty when in fact it is clean.
657  * This should only affect volumes that have not been shutdown cleanly but did
658  * not have any pending, non-check-pointed i/o, i.e. they were completely idle
659  * at least for the five seconds preceding the unclean shutdown.
660  *
661  * This function assumes that the $LogFile journal has already been consistency
662  * checked by a call to ntfs_check_logfile() and in particular if the $LogFile
663  * is empty this function requires that NVolLogFileEmpty() is true otherwise an
664  * empty volume will be reported as dirty.
665  */
666 bool ntfs_is_logfile_clean(struct inode *log_vi, const RESTART_PAGE_HEADER *rp)
667 {
668         ntfs_volume *vol = NTFS_SB(log_vi->i_sb);
669         RESTART_AREA *ra;
670 
671         ntfs_debug("Entering.");
672         /* An empty $LogFile must have been clean before it got emptied. */
673         if (NVolLogFileEmpty(vol)) {
674                 ntfs_debug("Done.  ($LogFile is empty.)");
675                 return true;
676         }
677         BUG_ON(!rp);
678         if (!ntfs_is_rstr_record(rp->magic) &&
679                         !ntfs_is_chkd_record(rp->magic)) {
680                 ntfs_error(vol->sb, "Restart page buffer is invalid.  This is "
681                                 "probably a bug in that the $LogFile should "
682                                 "have been consistency checked before calling "
683                                 "this function.");
684                 return false;
685         }
686         ra = (RESTART_AREA*)((u8*)rp + le16_to_cpu(rp->restart_area_offset));
687         /*
688          * If the $LogFile has active clients, i.e. it is open, and we do not
689          * have the RESTART_VOLUME_IS_CLEAN bit set in the restart area flags,
690          * we assume there was an unclean shutdown.
691          */
692         if (ra->client_in_use_list != LOGFILE_NO_CLIENT &&
693                         !(ra->flags & RESTART_VOLUME_IS_CLEAN)) {
694                 ntfs_debug("Done.  $LogFile indicates a dirty shutdown.");
695                 return false;
696         }
697         /* $LogFile indicates a clean shutdown. */
698         ntfs_debug("Done.  $LogFile indicates a clean shutdown.");
699         return true;
700 }
701 
702 /**
703  * ntfs_empty_logfile - empty the contents of the $LogFile journal
704  * @log_vi:     struct inode of loaded journal $LogFile to empty
705  *
706  * Empty the contents of the $LogFile journal @log_vi and return 'true' on
707  * success and 'false' on error.
708  *
709  * This function assumes that the $LogFile journal has already been consistency
710  * checked by a call to ntfs_check_logfile() and that ntfs_is_logfile_clean()
711  * has been used to ensure that the $LogFile is clean.
712  */
713 bool ntfs_empty_logfile(struct inode *log_vi)
714 {
715         VCN vcn, end_vcn;
716         ntfs_inode *log_ni = NTFS_I(log_vi);
717         ntfs_volume *vol = log_ni->vol;
718         struct super_block *sb = vol->sb;
719         runlist_element *rl;
720         unsigned long flags;
721         unsigned block_size, block_size_bits;
722         int err;
723         bool should_wait = true;
724 
725         ntfs_debug("Entering.");
726         if (NVolLogFileEmpty(vol)) {
727                 ntfs_debug("Done.");
728                 return true;
729         }
730         /*
731          * We cannot use ntfs_attr_set() because we may be still in the middle
732          * of a mount operation.  Thus we do the emptying by hand by first
733          * zapping the page cache pages for the $LogFile/$DATA attribute and
734          * then emptying each of the buffers in each of the clusters specified
735          * by the runlist by hand.
736          */
737         block_size = sb->s_blocksize;
738         block_size_bits = sb->s_blocksize_bits;
739         vcn = 0;
740         read_lock_irqsave(&log_ni->size_lock, flags);
741         end_vcn = (log_ni->initialized_size + vol->cluster_size_mask) >>
742                         vol->cluster_size_bits;
743         read_unlock_irqrestore(&log_ni->size_lock, flags);
744         truncate_inode_pages(log_vi->i_mapping, 0);
745         down_write(&log_ni->runlist.lock);
746         rl = log_ni->runlist.rl;
747         if (unlikely(!rl || vcn < rl->vcn || !rl->length)) {
748 map_vcn:
749                 err = ntfs_map_runlist_nolock(log_ni, vcn, NULL);
750                 if (err) {
751                         ntfs_error(sb, "Failed to map runlist fragment (error "
752                                         "%d).", -err);
753                         goto err;
754                 }
755                 rl = log_ni->runlist.rl;
756                 BUG_ON(!rl || vcn < rl->vcn || !rl->length);
757         }
758         /* Seek to the runlist element containing @vcn. */
759         while (rl->length && vcn >= rl[1].vcn)
760                 rl++;
761         do {
762                 LCN lcn;
763                 sector_t block, end_block;
764                 s64 len;
765 
766                 /*
767                  * If this run is not mapped map it now and start again as the
768                  * runlist will have been updated.
769                  */
770                 lcn = rl->lcn;
771                 if (unlikely(lcn == LCN_RL_NOT_MAPPED)) {
772                         vcn = rl->vcn;
773                         goto map_vcn;
774                 }
775                 /* If this run is not valid abort with an error. */
776                 if (unlikely(!rl->length || lcn < LCN_HOLE))
777                         goto rl_err;
778                 /* Skip holes. */
779                 if (lcn == LCN_HOLE)
780                         continue;
781                 block = lcn << vol->cluster_size_bits >> block_size_bits;
782                 len = rl->length;
783                 if (rl[1].vcn > end_vcn)
784                         len = end_vcn - rl->vcn;
785                 end_block = (lcn + len) << vol->cluster_size_bits >>
786                                 block_size_bits;
787                 /* Iterate over the blocks in the run and empty them. */
788                 do {
789                         struct buffer_head *bh;
790 
791                         /* Obtain the buffer, possibly not uptodate. */
792                         bh = sb_getblk(sb, block);
793                         BUG_ON(!bh);
794                         /* Setup buffer i/o submission. */
795                         lock_buffer(bh);
796                         bh->b_end_io = end_buffer_write_sync;
797                         get_bh(bh);
798                         /* Set the entire contents of the buffer to 0xff. */
799                         memset(bh->b_data, -1, block_size);
800                         if (!buffer_uptodate(bh))
801                                 set_buffer_uptodate(bh);
802                         if (buffer_dirty(bh))
803                                 clear_buffer_dirty(bh);
804                         /*
805                          * Submit the buffer and wait for i/o to complete but
806                          * only for the first buffer so we do not miss really
807                          * serious i/o errors.  Once the first buffer has
808                          * completed ignore errors afterwards as we can assume
809                          * that if one buffer worked all of them will work.
810                          */
811                         submit_bh(REQ_OP_WRITE, 0, bh);
812                         if (should_wait) {
813                                 should_wait = false;
814                                 wait_on_buffer(bh);
815                                 if (unlikely(!buffer_uptodate(bh)))
816                                         goto io_err;
817                         }
818                         brelse(bh);
819                 } while (++block < end_block);
820         } while ((++rl)->vcn < end_vcn);
821         up_write(&log_ni->runlist.lock);
822         /*
823          * Zap the pages again just in case any got instantiated whilst we were
824          * emptying the blocks by hand.  FIXME: We may not have completed
825          * writing to all the buffer heads yet so this may happen too early.
826          * We really should use a kernel thread to do the emptying
827          * asynchronously and then we can also set the volume dirty and output
828          * an error message if emptying should fail.
829          */
830         truncate_inode_pages(log_vi->i_mapping, 0);
831         /* Set the flag so we do not have to do it again on remount. */
832         NVolSetLogFileEmpty(vol);
833         ntfs_debug("Done.");
834         return true;
835 io_err:
836         ntfs_error(sb, "Failed to write buffer.  Unmount and run chkdsk.");
837         goto dirty_err;
838 rl_err:
839         ntfs_error(sb, "Runlist is corrupt.  Unmount and run chkdsk.");
840 dirty_err:
841         NVolSetErrors(vol);
842         err = -EIO;
843 err:
844         up_write(&log_ni->runlist.lock);
845         ntfs_error(sb, "Failed to fill $LogFile with 0xff bytes (error %d).",
846                         -err);
847         return false;
848 }
849 
850 #endif /* NTFS_RW */
851 

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