1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 2017 Oracle. All Rights Reserved.
4 *
5 * Author: Darrick J. Wong <darrick.wong@oracle.com>
6 */
7 #include "ext4.h"
8 #include <linux/fsmap.h>
9 #include "fsmap.h"
10 #include "mballoc.h"
11 #include <linux/sort.h>
12 #include <linux/list_sort.h>
13 #include <trace/events/ext4.h>
14
15 /* Convert an ext4_fsmap to an fsmap. */
ext4_fsmap_from_internal(struct super_block * sb,struct fsmap * dest,struct ext4_fsmap * src)16 void ext4_fsmap_from_internal(struct super_block *sb, struct fsmap *dest,
17 struct ext4_fsmap *src)
18 {
19 dest->fmr_device = src->fmr_device;
20 dest->fmr_flags = src->fmr_flags;
21 dest->fmr_physical = src->fmr_physical << sb->s_blocksize_bits;
22 dest->fmr_owner = src->fmr_owner;
23 dest->fmr_offset = 0;
24 dest->fmr_length = src->fmr_length << sb->s_blocksize_bits;
25 dest->fmr_reserved[0] = 0;
26 dest->fmr_reserved[1] = 0;
27 dest->fmr_reserved[2] = 0;
28 }
29
30 /* Convert an fsmap to an ext4_fsmap. */
ext4_fsmap_to_internal(struct super_block * sb,struct ext4_fsmap * dest,struct fsmap * src)31 void ext4_fsmap_to_internal(struct super_block *sb, struct ext4_fsmap *dest,
32 struct fsmap *src)
33 {
34 dest->fmr_device = src->fmr_device;
35 dest->fmr_flags = src->fmr_flags;
36 dest->fmr_physical = src->fmr_physical >> sb->s_blocksize_bits;
37 dest->fmr_owner = src->fmr_owner;
38 dest->fmr_length = src->fmr_length >> sb->s_blocksize_bits;
39 }
40
41 /* getfsmap query state */
42 struct ext4_getfsmap_info {
43 struct ext4_fsmap_head *gfi_head;
44 ext4_fsmap_format_t gfi_formatter; /* formatting fn */
45 void *gfi_format_arg;/* format buffer */
46 ext4_fsblk_t gfi_next_fsblk; /* next fsblock we expect */
47 u32 gfi_dev; /* device id */
48 ext4_group_t gfi_agno; /* bg number, if applicable */
49 struct ext4_fsmap gfi_low; /* low rmap key */
50 struct ext4_fsmap gfi_high; /* high rmap key */
51 struct ext4_fsmap gfi_lastfree; /* free ext at end of last bg */
52 struct list_head gfi_meta_list; /* fixed metadata list */
53 bool gfi_last; /* last extent? */
54 };
55
56 /* Associate a device with a getfsmap handler. */
57 struct ext4_getfsmap_dev {
58 int (*gfd_fn)(struct super_block *sb,
59 struct ext4_fsmap *keys,
60 struct ext4_getfsmap_info *info);
61 u32 gfd_dev;
62 };
63
64 /* Compare two getfsmap device handlers. */
ext4_getfsmap_dev_compare(const void * p1,const void * p2)65 static int ext4_getfsmap_dev_compare(const void *p1, const void *p2)
66 {
67 const struct ext4_getfsmap_dev *d1 = p1;
68 const struct ext4_getfsmap_dev *d2 = p2;
69
70 return d1->gfd_dev - d2->gfd_dev;
71 }
72
73 /* Compare a record against our starting point */
ext4_getfsmap_rec_before_low_key(struct ext4_getfsmap_info * info,struct ext4_fsmap * rec)74 static bool ext4_getfsmap_rec_before_low_key(struct ext4_getfsmap_info *info,
75 struct ext4_fsmap *rec)
76 {
77 return rec->fmr_physical < info->gfi_low.fmr_physical;
78 }
79
80 /*
81 * Format a reverse mapping for getfsmap, having translated rm_startblock
82 * into the appropriate daddr units.
83 */
ext4_getfsmap_helper(struct super_block * sb,struct ext4_getfsmap_info * info,struct ext4_fsmap * rec)84 static int ext4_getfsmap_helper(struct super_block *sb,
85 struct ext4_getfsmap_info *info,
86 struct ext4_fsmap *rec)
87 {
88 struct ext4_fsmap fmr;
89 struct ext4_sb_info *sbi = EXT4_SB(sb);
90 ext4_fsblk_t rec_fsblk = rec->fmr_physical;
91 ext4_group_t agno;
92 ext4_grpblk_t cno;
93 int error;
94
95 if (fatal_signal_pending(current))
96 return -EINTR;
97
98 /*
99 * Filter out records that start before our startpoint, if the
100 * caller requested that.
101 */
102 if (ext4_getfsmap_rec_before_low_key(info, rec)) {
103 rec_fsblk += rec->fmr_length;
104 if (info->gfi_next_fsblk < rec_fsblk)
105 info->gfi_next_fsblk = rec_fsblk;
106 return EXT4_QUERY_RANGE_CONTINUE;
107 }
108
109 /* Are we just counting mappings? */
110 if (info->gfi_head->fmh_count == 0) {
111 if (info->gfi_head->fmh_entries == UINT_MAX)
112 return EXT4_QUERY_RANGE_ABORT;
113
114 if (rec_fsblk > info->gfi_next_fsblk)
115 info->gfi_head->fmh_entries++;
116
117 if (info->gfi_last)
118 return EXT4_QUERY_RANGE_CONTINUE;
119
120 info->gfi_head->fmh_entries++;
121
122 rec_fsblk += rec->fmr_length;
123 if (info->gfi_next_fsblk < rec_fsblk)
124 info->gfi_next_fsblk = rec_fsblk;
125 return EXT4_QUERY_RANGE_CONTINUE;
126 }
127
128 /*
129 * If the record starts past the last physical block we saw,
130 * then we've found a gap. Report the gap as being owned by
131 * whatever the caller specified is the missing owner.
132 */
133 if (rec_fsblk > info->gfi_next_fsblk) {
134 if (info->gfi_head->fmh_entries >= info->gfi_head->fmh_count)
135 return EXT4_QUERY_RANGE_ABORT;
136
137 ext4_get_group_no_and_offset(sb, info->gfi_next_fsblk,
138 &agno, &cno);
139 trace_ext4_fsmap_mapping(sb, info->gfi_dev, agno,
140 EXT4_C2B(sbi, cno),
141 rec_fsblk - info->gfi_next_fsblk,
142 EXT4_FMR_OWN_UNKNOWN);
143
144 fmr.fmr_device = info->gfi_dev;
145 fmr.fmr_physical = info->gfi_next_fsblk;
146 fmr.fmr_owner = EXT4_FMR_OWN_UNKNOWN;
147 fmr.fmr_length = rec_fsblk - info->gfi_next_fsblk;
148 fmr.fmr_flags = FMR_OF_SPECIAL_OWNER;
149 error = info->gfi_formatter(&fmr, info->gfi_format_arg);
150 if (error)
151 return error;
152 info->gfi_head->fmh_entries++;
153 }
154
155 if (info->gfi_last)
156 goto out;
157
158 /* Fill out the extent we found */
159 if (info->gfi_head->fmh_entries >= info->gfi_head->fmh_count)
160 return EXT4_QUERY_RANGE_ABORT;
161
162 ext4_get_group_no_and_offset(sb, rec_fsblk, &agno, &cno);
163 trace_ext4_fsmap_mapping(sb, info->gfi_dev, agno, EXT4_C2B(sbi, cno),
164 rec->fmr_length, rec->fmr_owner);
165
166 fmr.fmr_device = info->gfi_dev;
167 fmr.fmr_physical = rec_fsblk;
168 fmr.fmr_owner = rec->fmr_owner;
169 fmr.fmr_flags = FMR_OF_SPECIAL_OWNER;
170 fmr.fmr_length = rec->fmr_length;
171 error = info->gfi_formatter(&fmr, info->gfi_format_arg);
172 if (error)
173 return error;
174 info->gfi_head->fmh_entries++;
175
176 out:
177 rec_fsblk += rec->fmr_length;
178 if (info->gfi_next_fsblk < rec_fsblk)
179 info->gfi_next_fsblk = rec_fsblk;
180 return EXT4_QUERY_RANGE_CONTINUE;
181 }
182
ext4_fsmap_next_pblk(struct ext4_fsmap * fmr)183 static inline ext4_fsblk_t ext4_fsmap_next_pblk(struct ext4_fsmap *fmr)
184 {
185 return fmr->fmr_physical + fmr->fmr_length;
186 }
187
188 /* Transform a blockgroup's free record into a fsmap */
ext4_getfsmap_datadev_helper(struct super_block * sb,ext4_group_t agno,ext4_grpblk_t start,ext4_grpblk_t len,void * priv)189 static int ext4_getfsmap_datadev_helper(struct super_block *sb,
190 ext4_group_t agno, ext4_grpblk_t start,
191 ext4_grpblk_t len, void *priv)
192 {
193 struct ext4_fsmap irec;
194 struct ext4_getfsmap_info *info = priv;
195 struct ext4_fsmap *p;
196 struct ext4_fsmap *tmp;
197 struct ext4_sb_info *sbi = EXT4_SB(sb);
198 ext4_fsblk_t fsb;
199 ext4_fsblk_t fslen;
200 int error;
201
202 fsb = (EXT4_C2B(sbi, start) + ext4_group_first_block_no(sb, agno));
203 fslen = EXT4_C2B(sbi, len);
204
205 /* If the retained free extent record is set... */
206 if (info->gfi_lastfree.fmr_owner) {
207 /* ...and abuts this one, lengthen it and return. */
208 if (ext4_fsmap_next_pblk(&info->gfi_lastfree) == fsb) {
209 info->gfi_lastfree.fmr_length += fslen;
210 return 0;
211 }
212
213 /*
214 * There's a gap between the two free extents; emit the
215 * retained extent prior to merging the meta_list.
216 */
217 error = ext4_getfsmap_helper(sb, info, &info->gfi_lastfree);
218 if (error)
219 return error;
220 info->gfi_lastfree.fmr_owner = 0;
221 }
222
223 /* Merge in any relevant extents from the meta_list */
224 list_for_each_entry_safe(p, tmp, &info->gfi_meta_list, fmr_list) {
225 if (p->fmr_physical + p->fmr_length <= info->gfi_next_fsblk) {
226 list_del(&p->fmr_list);
227 kfree(p);
228 } else if (p->fmr_physical < fsb) {
229 error = ext4_getfsmap_helper(sb, info, p);
230 if (error)
231 return error;
232
233 list_del(&p->fmr_list);
234 kfree(p);
235 }
236 }
237
238 irec.fmr_device = 0;
239 irec.fmr_physical = fsb;
240 irec.fmr_length = fslen;
241 irec.fmr_owner = EXT4_FMR_OWN_FREE;
242 irec.fmr_flags = 0;
243
244 /* If this is a free extent at the end of a bg, buffer it. */
245 if (ext4_fsmap_next_pblk(&irec) ==
246 ext4_group_first_block_no(sb, agno + 1)) {
247 info->gfi_lastfree = irec;
248 return 0;
249 }
250
251 /* Otherwise, emit it */
252 return ext4_getfsmap_helper(sb, info, &irec);
253 }
254
255 /* Execute a getfsmap query against the log device. */
ext4_getfsmap_logdev(struct super_block * sb,struct ext4_fsmap * keys,struct ext4_getfsmap_info * info)256 static int ext4_getfsmap_logdev(struct super_block *sb, struct ext4_fsmap *keys,
257 struct ext4_getfsmap_info *info)
258 {
259 journal_t *journal = EXT4_SB(sb)->s_journal;
260 struct ext4_fsmap irec;
261
262 /* Set up search keys */
263 info->gfi_low = keys[0];
264 info->gfi_low.fmr_length = 0;
265
266 memset(&info->gfi_high, 0xFF, sizeof(info->gfi_high));
267
268 trace_ext4_fsmap_low_key(sb, info->gfi_dev, 0,
269 info->gfi_low.fmr_physical,
270 info->gfi_low.fmr_length,
271 info->gfi_low.fmr_owner);
272
273 trace_ext4_fsmap_high_key(sb, info->gfi_dev, 0,
274 info->gfi_high.fmr_physical,
275 info->gfi_high.fmr_length,
276 info->gfi_high.fmr_owner);
277
278 if (keys[0].fmr_physical > 0)
279 return 0;
280
281 /* Fabricate an rmap entry for the external log device. */
282 irec.fmr_physical = journal->j_blk_offset;
283 irec.fmr_length = journal->j_total_len;
284 irec.fmr_owner = EXT4_FMR_OWN_LOG;
285 irec.fmr_flags = 0;
286
287 return ext4_getfsmap_helper(sb, info, &irec);
288 }
289
290 /* Helper to fill out an ext4_fsmap. */
ext4_getfsmap_fill(struct list_head * meta_list,ext4_fsblk_t fsb,ext4_fsblk_t len,uint64_t owner)291 static inline int ext4_getfsmap_fill(struct list_head *meta_list,
292 ext4_fsblk_t fsb, ext4_fsblk_t len,
293 uint64_t owner)
294 {
295 struct ext4_fsmap *fsm;
296
297 fsm = kmalloc(sizeof(*fsm), GFP_NOFS);
298 if (!fsm)
299 return -ENOMEM;
300 fsm->fmr_device = 0;
301 fsm->fmr_flags = 0;
302 fsm->fmr_physical = fsb;
303 fsm->fmr_owner = owner;
304 fsm->fmr_length = len;
305 list_add_tail(&fsm->fmr_list, meta_list);
306
307 return 0;
308 }
309
310 /*
311 * This function returns the number of file system metadata blocks at
312 * the beginning of a block group, including the reserved gdt blocks.
313 */
ext4_getfsmap_find_sb(struct super_block * sb,ext4_group_t agno,struct list_head * meta_list)314 static unsigned int ext4_getfsmap_find_sb(struct super_block *sb,
315 ext4_group_t agno,
316 struct list_head *meta_list)
317 {
318 struct ext4_sb_info *sbi = EXT4_SB(sb);
319 ext4_fsblk_t fsb = ext4_group_first_block_no(sb, agno);
320 ext4_fsblk_t len;
321 unsigned long first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
322 unsigned long metagroup = agno / EXT4_DESC_PER_BLOCK(sb);
323 int error;
324
325 /* Record the superblock. */
326 if (ext4_bg_has_super(sb, agno)) {
327 error = ext4_getfsmap_fill(meta_list, fsb, 1, EXT4_FMR_OWN_FS);
328 if (error)
329 return error;
330 fsb++;
331 }
332
333 /* Record the group descriptors. */
334 len = ext4_bg_num_gdb(sb, agno);
335 if (!len)
336 return 0;
337 error = ext4_getfsmap_fill(meta_list, fsb, len,
338 EXT4_FMR_OWN_GDT);
339 if (error)
340 return error;
341 fsb += len;
342
343 /* Reserved GDT blocks */
344 if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg) {
345 len = le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
346 error = ext4_getfsmap_fill(meta_list, fsb, len,
347 EXT4_FMR_OWN_RESV_GDT);
348 if (error)
349 return error;
350 }
351
352 return 0;
353 }
354
355 /* Compare two fsmap items. */
ext4_getfsmap_compare(void * priv,const struct list_head * a,const struct list_head * b)356 static int ext4_getfsmap_compare(void *priv,
357 const struct list_head *a,
358 const struct list_head *b)
359 {
360 struct ext4_fsmap *fa;
361 struct ext4_fsmap *fb;
362
363 fa = container_of(a, struct ext4_fsmap, fmr_list);
364 fb = container_of(b, struct ext4_fsmap, fmr_list);
365 if (fa->fmr_physical < fb->fmr_physical)
366 return -1;
367 else if (fa->fmr_physical > fb->fmr_physical)
368 return 1;
369 return 0;
370 }
371
372 /* Merge adjacent extents of fixed metadata. */
ext4_getfsmap_merge_fixed_metadata(struct list_head * meta_list)373 static void ext4_getfsmap_merge_fixed_metadata(struct list_head *meta_list)
374 {
375 struct ext4_fsmap *p;
376 struct ext4_fsmap *prev = NULL;
377 struct ext4_fsmap *tmp;
378
379 list_for_each_entry_safe(p, tmp, meta_list, fmr_list) {
380 if (!prev) {
381 prev = p;
382 continue;
383 }
384
385 if (prev->fmr_owner == p->fmr_owner &&
386 prev->fmr_physical + prev->fmr_length == p->fmr_physical) {
387 prev->fmr_length += p->fmr_length;
388 list_del(&p->fmr_list);
389 kfree(p);
390 } else
391 prev = p;
392 }
393 }
394
395 /* Free a list of fixed metadata. */
ext4_getfsmap_free_fixed_metadata(struct list_head * meta_list)396 static void ext4_getfsmap_free_fixed_metadata(struct list_head *meta_list)
397 {
398 struct ext4_fsmap *p;
399 struct ext4_fsmap *tmp;
400
401 list_for_each_entry_safe(p, tmp, meta_list, fmr_list) {
402 list_del(&p->fmr_list);
403 kfree(p);
404 }
405 }
406
407 /* Find all the fixed metadata in the filesystem. */
ext4_getfsmap_find_fixed_metadata(struct super_block * sb,struct list_head * meta_list)408 static int ext4_getfsmap_find_fixed_metadata(struct super_block *sb,
409 struct list_head *meta_list)
410 {
411 struct ext4_group_desc *gdp;
412 ext4_group_t agno;
413 int error;
414
415 INIT_LIST_HEAD(meta_list);
416
417 /* Collect everything. */
418 for (agno = 0; agno < EXT4_SB(sb)->s_groups_count; agno++) {
419 gdp = ext4_get_group_desc(sb, agno, NULL);
420 if (!gdp) {
421 error = -EFSCORRUPTED;
422 goto err;
423 }
424
425 /* Superblock & GDT */
426 error = ext4_getfsmap_find_sb(sb, agno, meta_list);
427 if (error)
428 goto err;
429
430 /* Block bitmap */
431 error = ext4_getfsmap_fill(meta_list,
432 ext4_block_bitmap(sb, gdp), 1,
433 EXT4_FMR_OWN_BLKBM);
434 if (error)
435 goto err;
436
437 /* Inode bitmap */
438 error = ext4_getfsmap_fill(meta_list,
439 ext4_inode_bitmap(sb, gdp), 1,
440 EXT4_FMR_OWN_INOBM);
441 if (error)
442 goto err;
443
444 /* Inodes */
445 error = ext4_getfsmap_fill(meta_list,
446 ext4_inode_table(sb, gdp),
447 EXT4_SB(sb)->s_itb_per_group,
448 EXT4_FMR_OWN_INODES);
449 if (error)
450 goto err;
451 }
452
453 /* Sort the list */
454 list_sort(NULL, meta_list, ext4_getfsmap_compare);
455
456 /* Merge adjacent extents */
457 ext4_getfsmap_merge_fixed_metadata(meta_list);
458
459 return 0;
460 err:
461 ext4_getfsmap_free_fixed_metadata(meta_list);
462 return error;
463 }
464
465 /* Execute a getfsmap query against the buddy bitmaps */
ext4_getfsmap_datadev(struct super_block * sb,struct ext4_fsmap * keys,struct ext4_getfsmap_info * info)466 static int ext4_getfsmap_datadev(struct super_block *sb,
467 struct ext4_fsmap *keys,
468 struct ext4_getfsmap_info *info)
469 {
470 struct ext4_sb_info *sbi = EXT4_SB(sb);
471 ext4_fsblk_t start_fsb;
472 ext4_fsblk_t end_fsb;
473 ext4_fsblk_t bofs;
474 ext4_fsblk_t eofs;
475 ext4_group_t start_ag;
476 ext4_group_t end_ag;
477 ext4_grpblk_t first_cluster;
478 ext4_grpblk_t last_cluster;
479 int error = 0;
480
481 bofs = le32_to_cpu(sbi->s_es->s_first_data_block);
482 eofs = ext4_blocks_count(sbi->s_es);
483 if (keys[0].fmr_physical >= eofs)
484 return 0;
485 else if (keys[0].fmr_physical < bofs)
486 keys[0].fmr_physical = bofs;
487 if (keys[1].fmr_physical >= eofs)
488 keys[1].fmr_physical = eofs - 1;
489 if (keys[1].fmr_physical < keys[0].fmr_physical)
490 return 0;
491 start_fsb = keys[0].fmr_physical;
492 end_fsb = keys[1].fmr_physical;
493
494 /* Determine first and last group to examine based on start and end */
495 ext4_get_group_no_and_offset(sb, start_fsb, &start_ag, &first_cluster);
496 ext4_get_group_no_and_offset(sb, end_fsb, &end_ag, &last_cluster);
497
498 /*
499 * Convert the fsmap low/high keys to bg based keys. Initialize
500 * low to the fsmap low key and max out the high key to the end
501 * of the bg.
502 */
503 info->gfi_low = keys[0];
504 info->gfi_low.fmr_physical = EXT4_C2B(sbi, first_cluster);
505 info->gfi_low.fmr_length = 0;
506
507 memset(&info->gfi_high, 0xFF, sizeof(info->gfi_high));
508
509 /* Assemble a list of all the fixed-location metadata. */
510 error = ext4_getfsmap_find_fixed_metadata(sb, &info->gfi_meta_list);
511 if (error)
512 goto err;
513
514 /* Query each bg */
515 for (info->gfi_agno = start_ag;
516 info->gfi_agno <= end_ag;
517 info->gfi_agno++) {
518 /*
519 * Set the bg high key from the fsmap high key if this
520 * is the last bg that we're querying.
521 */
522 if (info->gfi_agno == end_ag) {
523 info->gfi_high = keys[1];
524 info->gfi_high.fmr_physical = EXT4_C2B(sbi,
525 last_cluster);
526 info->gfi_high.fmr_length = 0;
527 }
528
529 trace_ext4_fsmap_low_key(sb, info->gfi_dev, info->gfi_agno,
530 info->gfi_low.fmr_physical,
531 info->gfi_low.fmr_length,
532 info->gfi_low.fmr_owner);
533
534 trace_ext4_fsmap_high_key(sb, info->gfi_dev, info->gfi_agno,
535 info->gfi_high.fmr_physical,
536 info->gfi_high.fmr_length,
537 info->gfi_high.fmr_owner);
538
539 error = ext4_mballoc_query_range(sb, info->gfi_agno,
540 EXT4_B2C(sbi, info->gfi_low.fmr_physical),
541 EXT4_B2C(sbi, info->gfi_high.fmr_physical),
542 ext4_getfsmap_datadev_helper, info);
543 if (error)
544 goto err;
545
546 /*
547 * Set the bg low key to the start of the bg prior to
548 * moving on to the next bg.
549 */
550 if (info->gfi_agno == start_ag)
551 memset(&info->gfi_low, 0, sizeof(info->gfi_low));
552 }
553
554 /* Do we have a retained free extent? */
555 if (info->gfi_lastfree.fmr_owner) {
556 error = ext4_getfsmap_helper(sb, info, &info->gfi_lastfree);
557 if (error)
558 goto err;
559 }
560
561 /* Report any gaps at the end of the bg */
562 info->gfi_last = true;
563 error = ext4_getfsmap_datadev_helper(sb, end_ag, last_cluster, 0, info);
564 if (error)
565 goto err;
566
567 err:
568 ext4_getfsmap_free_fixed_metadata(&info->gfi_meta_list);
569 return error;
570 }
571
572 /* Do we recognize the device? */
ext4_getfsmap_is_valid_device(struct super_block * sb,struct ext4_fsmap * fm)573 static bool ext4_getfsmap_is_valid_device(struct super_block *sb,
574 struct ext4_fsmap *fm)
575 {
576 if (fm->fmr_device == 0 || fm->fmr_device == UINT_MAX ||
577 fm->fmr_device == new_encode_dev(sb->s_bdev->bd_dev))
578 return true;
579 if (EXT4_SB(sb)->s_journal_bdev_file &&
580 fm->fmr_device ==
581 new_encode_dev(file_bdev(EXT4_SB(sb)->s_journal_bdev_file)->bd_dev))
582 return true;
583 return false;
584 }
585
586 /* Ensure that the low key is less than the high key. */
ext4_getfsmap_check_keys(struct ext4_fsmap * low_key,struct ext4_fsmap * high_key)587 static bool ext4_getfsmap_check_keys(struct ext4_fsmap *low_key,
588 struct ext4_fsmap *high_key)
589 {
590 if (low_key->fmr_device > high_key->fmr_device)
591 return false;
592 if (low_key->fmr_device < high_key->fmr_device)
593 return true;
594
595 if (low_key->fmr_physical > high_key->fmr_physical)
596 return false;
597 if (low_key->fmr_physical < high_key->fmr_physical)
598 return true;
599
600 if (low_key->fmr_owner > high_key->fmr_owner)
601 return false;
602 if (low_key->fmr_owner < high_key->fmr_owner)
603 return true;
604
605 return false;
606 }
607
608 #define EXT4_GETFSMAP_DEVS 2
609 /*
610 * Get filesystem's extents as described in head, and format for
611 * output. Calls formatter to fill the user's buffer until all
612 * extents are mapped, until the passed-in head->fmh_count slots have
613 * been filled, or until the formatter short-circuits the loop, if it
614 * is tracking filled-in extents on its own.
615 *
616 * Key to Confusion
617 * ----------------
618 * There are multiple levels of keys and counters at work here:
619 * _fsmap_head.fmh_keys -- low and high fsmap keys passed in;
620 * these reflect fs-wide block addrs.
621 * dkeys -- fmh_keys used to query each device;
622 * these are fmh_keys but w/ the low key
623 * bumped up by fmr_length.
624 * _getfsmap_info.gfi_next_fsblk-- next fs block we expect to see; this
625 * is how we detect gaps in the fsmap
626 * records and report them.
627 * _getfsmap_info.gfi_low/high -- per-bg low/high keys computed from
628 * dkeys; used to query the free space.
629 */
ext4_getfsmap(struct super_block * sb,struct ext4_fsmap_head * head,ext4_fsmap_format_t formatter,void * arg)630 int ext4_getfsmap(struct super_block *sb, struct ext4_fsmap_head *head,
631 ext4_fsmap_format_t formatter, void *arg)
632 {
633 struct ext4_fsmap dkeys[2]; /* per-dev keys */
634 struct ext4_getfsmap_dev handlers[EXT4_GETFSMAP_DEVS];
635 struct ext4_getfsmap_info info = { NULL };
636 int i;
637 int error = 0;
638
639 if (head->fmh_iflags & ~FMH_IF_VALID)
640 return -EINVAL;
641 if (!ext4_getfsmap_is_valid_device(sb, &head->fmh_keys[0]) ||
642 !ext4_getfsmap_is_valid_device(sb, &head->fmh_keys[1]))
643 return -EINVAL;
644
645 head->fmh_entries = 0;
646
647 /* Set up our device handlers. */
648 memset(handlers, 0, sizeof(handlers));
649 handlers[0].gfd_dev = new_encode_dev(sb->s_bdev->bd_dev);
650 handlers[0].gfd_fn = ext4_getfsmap_datadev;
651 if (EXT4_SB(sb)->s_journal_bdev_file) {
652 handlers[1].gfd_dev = new_encode_dev(
653 file_bdev(EXT4_SB(sb)->s_journal_bdev_file)->bd_dev);
654 handlers[1].gfd_fn = ext4_getfsmap_logdev;
655 }
656
657 sort(handlers, EXT4_GETFSMAP_DEVS, sizeof(struct ext4_getfsmap_dev),
658 ext4_getfsmap_dev_compare, NULL);
659
660 /*
661 * To continue where we left off, we allow userspace to use the
662 * last mapping from a previous call as the low key of the next.
663 * This is identified by a non-zero length in the low key. We
664 * have to increment the low key in this scenario to ensure we
665 * don't return the same mapping again, and instead return the
666 * very next mapping.
667 *
668 * Bump the physical offset as there can be no other mapping for
669 * the same physical block range.
670 */
671 dkeys[0] = head->fmh_keys[0];
672 dkeys[0].fmr_physical += dkeys[0].fmr_length;
673 dkeys[0].fmr_owner = 0;
674 dkeys[0].fmr_length = 0;
675 memset(&dkeys[1], 0xFF, sizeof(struct ext4_fsmap));
676
677 if (!ext4_getfsmap_check_keys(dkeys, &head->fmh_keys[1]))
678 return -EINVAL;
679
680 info.gfi_next_fsblk = head->fmh_keys[0].fmr_physical +
681 head->fmh_keys[0].fmr_length;
682 info.gfi_formatter = formatter;
683 info.gfi_format_arg = arg;
684 info.gfi_head = head;
685
686 /* For each device we support... */
687 for (i = 0; i < EXT4_GETFSMAP_DEVS; i++) {
688 /* Is this device within the range the user asked for? */
689 if (!handlers[i].gfd_fn)
690 continue;
691 if (head->fmh_keys[0].fmr_device > handlers[i].gfd_dev)
692 continue;
693 if (head->fmh_keys[1].fmr_device < handlers[i].gfd_dev)
694 break;
695
696 /*
697 * If this device number matches the high key, we have
698 * to pass the high key to the handler to limit the
699 * query results. If the device number exceeds the
700 * low key, zero out the low key so that we get
701 * everything from the beginning.
702 */
703 if (handlers[i].gfd_dev == head->fmh_keys[1].fmr_device)
704 dkeys[1] = head->fmh_keys[1];
705 if (handlers[i].gfd_dev > head->fmh_keys[0].fmr_device)
706 memset(&dkeys[0], 0, sizeof(struct ext4_fsmap));
707
708 info.gfi_dev = handlers[i].gfd_dev;
709 info.gfi_last = false;
710 info.gfi_agno = -1;
711 error = handlers[i].gfd_fn(sb, dkeys, &info);
712 if (error)
713 break;
714 info.gfi_next_fsblk = 0;
715 }
716
717 head->fmh_oflags = FMH_OF_DEV_T;
718 return error;
719 }
720