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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. */
16void 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. */
31void 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 */
42struct 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. */
57struct 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. */
65static 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 */
74static 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 */
84static 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
176out:
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
183static 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 */
189static 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. */
256static 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. */
291static 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 */
314static 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. */
356static 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. */
373static 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. */
396static 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. */
408static 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;
460err:
461 ext4_getfsmap_free_fixed_metadata(meta_list);
462 return error;
463}
464
465/* Execute a getfsmap query against the buddy bitmaps */
466static 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 start_fsb = keys[0].fmr_physical;
490 end_fsb = keys[1].fmr_physical;
491
492 /* Determine first and last group to examine based on start and end */
493 ext4_get_group_no_and_offset(sb, start_fsb, &start_ag, &first_cluster);
494 ext4_get_group_no_and_offset(sb, end_fsb, &end_ag, &last_cluster);
495
496 /*
497 * Convert the fsmap low/high keys to bg based keys. Initialize
498 * low to the fsmap low key and max out the high key to the end
499 * of the bg.
500 */
501 info->gfi_low = keys[0];
502 info->gfi_low.fmr_physical = EXT4_C2B(sbi, first_cluster);
503 info->gfi_low.fmr_length = 0;
504
505 memset(&info->gfi_high, 0xFF, sizeof(info->gfi_high));
506
507 /* Assemble a list of all the fixed-location metadata. */
508 error = ext4_getfsmap_find_fixed_metadata(sb, &info->gfi_meta_list);
509 if (error)
510 goto err;
511
512 /* Query each bg */
513 for (info->gfi_agno = start_ag;
514 info->gfi_agno <= end_ag;
515 info->gfi_agno++) {
516 /*
517 * Set the bg high key from the fsmap high key if this
518 * is the last bg that we're querying.
519 */
520 if (info->gfi_agno == end_ag) {
521 info->gfi_high = keys[1];
522 info->gfi_high.fmr_physical = EXT4_C2B(sbi,
523 last_cluster);
524 info->gfi_high.fmr_length = 0;
525 }
526
527 trace_ext4_fsmap_low_key(sb, info->gfi_dev, info->gfi_agno,
528 info->gfi_low.fmr_physical,
529 info->gfi_low.fmr_length,
530 info->gfi_low.fmr_owner);
531
532 trace_ext4_fsmap_high_key(sb, info->gfi_dev, info->gfi_agno,
533 info->gfi_high.fmr_physical,
534 info->gfi_high.fmr_length,
535 info->gfi_high.fmr_owner);
536
537 error = ext4_mballoc_query_range(sb, info->gfi_agno,
538 EXT4_B2C(sbi, info->gfi_low.fmr_physical),
539 EXT4_B2C(sbi, info->gfi_high.fmr_physical),
540 ext4_getfsmap_datadev_helper, info);
541 if (error)
542 goto err;
543
544 /*
545 * Set the bg low key to the start of the bg prior to
546 * moving on to the next bg.
547 */
548 if (info->gfi_agno == start_ag)
549 memset(&info->gfi_low, 0, sizeof(info->gfi_low));
550 }
551
552 /* Do we have a retained free extent? */
553 if (info->gfi_lastfree.fmr_owner) {
554 error = ext4_getfsmap_helper(sb, info, &info->gfi_lastfree);
555 if (error)
556 goto err;
557 }
558
559 /* Report any gaps at the end of the bg */
560 info->gfi_last = true;
561 error = ext4_getfsmap_datadev_helper(sb, end_ag, last_cluster, 0, info);
562 if (error)
563 goto err;
564
565err:
566 ext4_getfsmap_free_fixed_metadata(&info->gfi_meta_list);
567 return error;
568}
569
570/* Do we recognize the device? */
571static bool ext4_getfsmap_is_valid_device(struct super_block *sb,
572 struct ext4_fsmap *fm)
573{
574 if (fm->fmr_device == 0 || fm->fmr_device == UINT_MAX ||
575 fm->fmr_device == new_encode_dev(sb->s_bdev->bd_dev))
576 return true;
577 if (EXT4_SB(sb)->s_journal_bdev &&
578 fm->fmr_device == new_encode_dev(EXT4_SB(sb)->s_journal_bdev->bd_dev))
579 return true;
580 return false;
581}
582
583/* Ensure that the low key is less than the high key. */
584static bool ext4_getfsmap_check_keys(struct ext4_fsmap *low_key,
585 struct ext4_fsmap *high_key)
586{
587 if (low_key->fmr_device > high_key->fmr_device)
588 return false;
589 if (low_key->fmr_device < high_key->fmr_device)
590 return true;
591
592 if (low_key->fmr_physical > high_key->fmr_physical)
593 return false;
594 if (low_key->fmr_physical < high_key->fmr_physical)
595 return true;
596
597 if (low_key->fmr_owner > high_key->fmr_owner)
598 return false;
599 if (low_key->fmr_owner < high_key->fmr_owner)
600 return true;
601
602 return false;
603}
604
605#define EXT4_GETFSMAP_DEVS 2
606/*
607 * Get filesystem's extents as described in head, and format for
608 * output. Calls formatter to fill the user's buffer until all
609 * extents are mapped, until the passed-in head->fmh_count slots have
610 * been filled, or until the formatter short-circuits the loop, if it
611 * is tracking filled-in extents on its own.
612 *
613 * Key to Confusion
614 * ----------------
615 * There are multiple levels of keys and counters at work here:
616 * _fsmap_head.fmh_keys -- low and high fsmap keys passed in;
617 * these reflect fs-wide block addrs.
618 * dkeys -- fmh_keys used to query each device;
619 * these are fmh_keys but w/ the low key
620 * bumped up by fmr_length.
621 * _getfsmap_info.gfi_next_fsblk-- next fs block we expect to see; this
622 * is how we detect gaps in the fsmap
623 * records and report them.
624 * _getfsmap_info.gfi_low/high -- per-bg low/high keys computed from
625 * dkeys; used to query the free space.
626 */
627int ext4_getfsmap(struct super_block *sb, struct ext4_fsmap_head *head,
628 ext4_fsmap_format_t formatter, void *arg)
629{
630 struct ext4_fsmap dkeys[2]; /* per-dev keys */
631 struct ext4_getfsmap_dev handlers[EXT4_GETFSMAP_DEVS];
632 struct ext4_getfsmap_info info = { NULL };
633 int i;
634 int error = 0;
635
636 if (head->fmh_iflags & ~FMH_IF_VALID)
637 return -EINVAL;
638 if (!ext4_getfsmap_is_valid_device(sb, &head->fmh_keys[0]) ||
639 !ext4_getfsmap_is_valid_device(sb, &head->fmh_keys[1]))
640 return -EINVAL;
641
642 head->fmh_entries = 0;
643
644 /* Set up our device handlers. */
645 memset(handlers, 0, sizeof(handlers));
646 handlers[0].gfd_dev = new_encode_dev(sb->s_bdev->bd_dev);
647 handlers[0].gfd_fn = ext4_getfsmap_datadev;
648 if (EXT4_SB(sb)->s_journal_bdev) {
649 handlers[1].gfd_dev = new_encode_dev(
650 EXT4_SB(sb)->s_journal_bdev->bd_dev);
651 handlers[1].gfd_fn = ext4_getfsmap_logdev;
652 }
653
654 sort(handlers, EXT4_GETFSMAP_DEVS, sizeof(struct ext4_getfsmap_dev),
655 ext4_getfsmap_dev_compare, NULL);
656
657 /*
658 * To continue where we left off, we allow userspace to use the
659 * last mapping from a previous call as the low key of the next.
660 * This is identified by a non-zero length in the low key. We
661 * have to increment the low key in this scenario to ensure we
662 * don't return the same mapping again, and instead return the
663 * very next mapping.
664 *
665 * Bump the physical offset as there can be no other mapping for
666 * the same physical block range.
667 */
668 dkeys[0] = head->fmh_keys[0];
669 dkeys[0].fmr_physical += dkeys[0].fmr_length;
670 dkeys[0].fmr_owner = 0;
671 dkeys[0].fmr_length = 0;
672 memset(&dkeys[1], 0xFF, sizeof(struct ext4_fsmap));
673
674 if (!ext4_getfsmap_check_keys(dkeys, &head->fmh_keys[1]))
675 return -EINVAL;
676
677 info.gfi_next_fsblk = head->fmh_keys[0].fmr_physical +
678 head->fmh_keys[0].fmr_length;
679 info.gfi_formatter = formatter;
680 info.gfi_format_arg = arg;
681 info.gfi_head = head;
682
683 /* For each device we support... */
684 for (i = 0; i < EXT4_GETFSMAP_DEVS; i++) {
685 /* Is this device within the range the user asked for? */
686 if (!handlers[i].gfd_fn)
687 continue;
688 if (head->fmh_keys[0].fmr_device > handlers[i].gfd_dev)
689 continue;
690 if (head->fmh_keys[1].fmr_device < handlers[i].gfd_dev)
691 break;
692
693 /*
694 * If this device number matches the high key, we have
695 * to pass the high key to the handler to limit the
696 * query results. If the device number exceeds the
697 * low key, zero out the low key so that we get
698 * everything from the beginning.
699 */
700 if (handlers[i].gfd_dev == head->fmh_keys[1].fmr_device)
701 dkeys[1] = head->fmh_keys[1];
702 if (handlers[i].gfd_dev > head->fmh_keys[0].fmr_device)
703 memset(&dkeys[0], 0, sizeof(struct ext4_fsmap));
704
705 info.gfi_dev = handlers[i].gfd_dev;
706 info.gfi_last = false;
707 info.gfi_agno = -1;
708 error = handlers[i].gfd_fn(sb, dkeys, &info);
709 if (error)
710 break;
711 info.gfi_next_fsblk = 0;
712 }
713
714 head->fmh_oflags = FMH_OF_DEV_T;
715 return error;
716}