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 + rec->fmr_length <=
78 info->gfi_low.fmr_physical;
79}
80
81/*
82 * Format a reverse mapping for getfsmap, having translated rm_startblock
83 * into the appropriate daddr units.
84 */
85static int ext4_getfsmap_helper(struct super_block *sb,
86 struct ext4_getfsmap_info *info,
87 struct ext4_fsmap *rec)
88{
89 struct ext4_fsmap fmr;
90 struct ext4_sb_info *sbi = EXT4_SB(sb);
91 ext4_fsblk_t rec_fsblk = rec->fmr_physical;
92 ext4_group_t agno;
93 ext4_grpblk_t cno;
94 int error;
95
96 if (fatal_signal_pending(current))
97 return -EINTR;
98
99 /*
100 * Filter out records that start before our startpoint, if the
101 * caller requested that.
102 */
103 if (ext4_getfsmap_rec_before_low_key(info, rec)) {
104 rec_fsblk += rec->fmr_length;
105 if (info->gfi_next_fsblk < rec_fsblk)
106 info->gfi_next_fsblk = rec_fsblk;
107 return EXT4_QUERY_RANGE_CONTINUE;
108 }
109
110 /* Are we just counting mappings? */
111 if (info->gfi_head->fmh_count == 0) {
112 if (info->gfi_head->fmh_entries == UINT_MAX)
113 return EXT4_QUERY_RANGE_ABORT;
114
115 if (rec_fsblk > info->gfi_next_fsblk)
116 info->gfi_head->fmh_entries++;
117
118 if (info->gfi_last)
119 return EXT4_QUERY_RANGE_CONTINUE;
120
121 info->gfi_head->fmh_entries++;
122
123 rec_fsblk += rec->fmr_length;
124 if (info->gfi_next_fsblk < rec_fsblk)
125 info->gfi_next_fsblk = rec_fsblk;
126 return EXT4_QUERY_RANGE_CONTINUE;
127 }
128
129 /*
130 * If the record starts past the last physical block we saw,
131 * then we've found a gap. Report the gap as being owned by
132 * whatever the caller specified is the missing owner.
133 */
134 if (rec_fsblk > info->gfi_next_fsblk) {
135 if (info->gfi_head->fmh_entries >= info->gfi_head->fmh_count)
136 return EXT4_QUERY_RANGE_ABORT;
137
138 ext4_get_group_no_and_offset(sb, blocknr: info->gfi_next_fsblk,
139 blockgrpp: &agno, offsetp: &cno);
140 trace_ext4_fsmap_mapping(sb, keydev: info->gfi_dev, agno,
141 EXT4_C2B(sbi, cno),
142 len: rec_fsblk - info->gfi_next_fsblk,
143 EXT4_FMR_OWN_UNKNOWN);
144
145 fmr.fmr_device = info->gfi_dev;
146 fmr.fmr_physical = info->gfi_next_fsblk;
147 fmr.fmr_owner = EXT4_FMR_OWN_UNKNOWN;
148 fmr.fmr_length = rec_fsblk - info->gfi_next_fsblk;
149 fmr.fmr_flags = FMR_OF_SPECIAL_OWNER;
150 error = info->gfi_formatter(&fmr, info->gfi_format_arg);
151 if (error)
152 return error;
153 info->gfi_head->fmh_entries++;
154 }
155
156 if (info->gfi_last)
157 goto out;
158
159 /* Fill out the extent we found */
160 if (info->gfi_head->fmh_entries >= info->gfi_head->fmh_count)
161 return EXT4_QUERY_RANGE_ABORT;
162
163 ext4_get_group_no_and_offset(sb, blocknr: rec_fsblk, blockgrpp: &agno, offsetp: &cno);
164 trace_ext4_fsmap_mapping(sb, keydev: info->gfi_dev, agno, EXT4_C2B(sbi, cno),
165 len: rec->fmr_length, owner: rec->fmr_owner);
166
167 fmr.fmr_device = info->gfi_dev;
168 fmr.fmr_physical = rec_fsblk;
169 fmr.fmr_owner = rec->fmr_owner;
170 fmr.fmr_flags = FMR_OF_SPECIAL_OWNER;
171 fmr.fmr_length = rec->fmr_length;
172 error = info->gfi_formatter(&fmr, info->gfi_format_arg);
173 if (error)
174 return error;
175 info->gfi_head->fmh_entries++;
176
177out:
178 rec_fsblk += rec->fmr_length;
179 if (info->gfi_next_fsblk < rec_fsblk)
180 info->gfi_next_fsblk = rec_fsblk;
181 return EXT4_QUERY_RANGE_CONTINUE;
182}
183
184static inline ext4_fsblk_t ext4_fsmap_next_pblk(struct ext4_fsmap *fmr)
185{
186 return fmr->fmr_physical + fmr->fmr_length;
187}
188
189static int ext4_getfsmap_meta_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_getfsmap_info *info = priv;
194 struct ext4_fsmap *p;
195 struct ext4_fsmap *tmp;
196 struct ext4_sb_info *sbi = EXT4_SB(sb);
197 ext4_fsblk_t fsb, fs_start, fs_end;
198 int error;
199
200 fs_start = fsb = (EXT4_C2B(sbi, start) +
201 ext4_group_first_block_no(sb, group_no: agno));
202 fs_end = fs_start + EXT4_C2B(sbi, len);
203
204 /*
205 * Return relevant extents from the meta_list. We emit all extents that
206 * partially/fully overlap with the query range
207 */
208 list_for_each_entry_safe(p, tmp, &info->gfi_meta_list, fmr_list) {
209 if (p->fmr_physical + p->fmr_length <= info->gfi_next_fsblk) {
210 list_del(entry: &p->fmr_list);
211 kfree(objp: p);
212 continue;
213 }
214 if (p->fmr_physical <= fs_end &&
215 p->fmr_physical + p->fmr_length > fs_start) {
216 /* Emit the retained free extent record if present */
217 if (info->gfi_lastfree.fmr_owner) {
218 error = ext4_getfsmap_helper(sb, info,
219 rec: &info->gfi_lastfree);
220 if (error)
221 return error;
222 info->gfi_lastfree.fmr_owner = 0;
223 }
224 error = ext4_getfsmap_helper(sb, info, rec: p);
225 if (error)
226 return error;
227 fsb = p->fmr_physical + p->fmr_length;
228 if (info->gfi_next_fsblk < fsb)
229 info->gfi_next_fsblk = fsb;
230 list_del(entry: &p->fmr_list);
231 kfree(objp: p);
232 continue;
233 }
234 }
235 if (info->gfi_next_fsblk < fsb)
236 info->gfi_next_fsblk = fsb;
237
238 return 0;
239}
240
241
242/* Transform a blockgroup's free record into a fsmap */
243static int ext4_getfsmap_datadev_helper(struct super_block *sb,
244 ext4_group_t agno, ext4_grpblk_t start,
245 ext4_grpblk_t len, void *priv)
246{
247 struct ext4_fsmap irec;
248 struct ext4_getfsmap_info *info = priv;
249 struct ext4_fsmap *p;
250 struct ext4_fsmap *tmp;
251 struct ext4_sb_info *sbi = EXT4_SB(sb);
252 ext4_fsblk_t fsb;
253 ext4_fsblk_t fslen;
254 int error;
255
256 fsb = (EXT4_C2B(sbi, start) + ext4_group_first_block_no(sb, group_no: agno));
257 fslen = EXT4_C2B(sbi, len);
258
259 /* If the retained free extent record is set... */
260 if (info->gfi_lastfree.fmr_owner) {
261 /* ...and abuts this one, lengthen it and return. */
262 if (ext4_fsmap_next_pblk(fmr: &info->gfi_lastfree) == fsb) {
263 info->gfi_lastfree.fmr_length += fslen;
264 return 0;
265 }
266
267 /*
268 * There's a gap between the two free extents; emit the
269 * retained extent prior to merging the meta_list.
270 */
271 error = ext4_getfsmap_helper(sb, info, rec: &info->gfi_lastfree);
272 if (error)
273 return error;
274 info->gfi_lastfree.fmr_owner = 0;
275 }
276
277 /* Merge in any relevant extents from the meta_list */
278 list_for_each_entry_safe(p, tmp, &info->gfi_meta_list, fmr_list) {
279 if (p->fmr_physical + p->fmr_length <= info->gfi_next_fsblk) {
280 list_del(entry: &p->fmr_list);
281 kfree(objp: p);
282 } else if (p->fmr_physical < fsb) {
283 error = ext4_getfsmap_helper(sb, info, rec: p);
284 if (error)
285 return error;
286
287 list_del(entry: &p->fmr_list);
288 kfree(objp: p);
289 }
290 }
291
292 irec.fmr_device = 0;
293 irec.fmr_physical = fsb;
294 irec.fmr_length = fslen;
295 irec.fmr_owner = EXT4_FMR_OWN_FREE;
296 irec.fmr_flags = 0;
297
298 /* If this is a free extent at the end of a bg, buffer it. */
299 if (ext4_fsmap_next_pblk(fmr: &irec) ==
300 ext4_group_first_block_no(sb, group_no: agno + 1)) {
301 info->gfi_lastfree = irec;
302 return 0;
303 }
304
305 /* Otherwise, emit it */
306 return ext4_getfsmap_helper(sb, info, rec: &irec);
307}
308
309/* Execute a getfsmap query against the log device. */
310static int ext4_getfsmap_logdev(struct super_block *sb, struct ext4_fsmap *keys,
311 struct ext4_getfsmap_info *info)
312{
313 journal_t *journal = EXT4_SB(sb)->s_journal;
314 struct ext4_fsmap irec;
315
316 /* Set up search keys */
317 info->gfi_low = keys[0];
318 info->gfi_low.fmr_length = 0;
319
320 memset(s: &info->gfi_high, c: 0xFF, n: sizeof(info->gfi_high));
321
322 trace_ext4_fsmap_low_key(sb, keydev: info->gfi_dev, agno: 0,
323 bno: info->gfi_low.fmr_physical,
324 len: info->gfi_low.fmr_length,
325 owner: info->gfi_low.fmr_owner);
326
327 trace_ext4_fsmap_high_key(sb, keydev: info->gfi_dev, agno: 0,
328 bno: info->gfi_high.fmr_physical,
329 len: info->gfi_high.fmr_length,
330 owner: info->gfi_high.fmr_owner);
331
332 if (keys[0].fmr_physical > 0)
333 return 0;
334
335 /* Fabricate an rmap entry for the external log device. */
336 irec.fmr_physical = journal->j_blk_offset;
337 irec.fmr_length = journal->j_total_len;
338 irec.fmr_owner = EXT4_FMR_OWN_LOG;
339 irec.fmr_flags = 0;
340
341 return ext4_getfsmap_helper(sb, info, rec: &irec);
342}
343
344/* Helper to fill out an ext4_fsmap. */
345static inline int ext4_getfsmap_fill(struct list_head *meta_list,
346 ext4_fsblk_t fsb, ext4_fsblk_t len,
347 uint64_t owner)
348{
349 struct ext4_fsmap *fsm;
350
351 fsm = kmalloc(sizeof(*fsm), GFP_NOFS);
352 if (!fsm)
353 return -ENOMEM;
354 fsm->fmr_device = 0;
355 fsm->fmr_flags = 0;
356 fsm->fmr_physical = fsb;
357 fsm->fmr_owner = owner;
358 fsm->fmr_length = len;
359 list_add_tail(new: &fsm->fmr_list, head: meta_list);
360
361 return 0;
362}
363
364/*
365 * This function returns the number of file system metadata blocks at
366 * the beginning of a block group, including the reserved gdt blocks.
367 */
368static unsigned int ext4_getfsmap_find_sb(struct super_block *sb,
369 ext4_group_t agno,
370 struct list_head *meta_list)
371{
372 struct ext4_sb_info *sbi = EXT4_SB(sb);
373 ext4_fsblk_t fsb = ext4_group_first_block_no(sb, group_no: agno);
374 ext4_fsblk_t len;
375 unsigned long first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
376 unsigned long metagroup = agno / EXT4_DESC_PER_BLOCK(sb);
377 int error;
378
379 /* Record the superblock. */
380 if (ext4_bg_has_super(sb, group: agno)) {
381 error = ext4_getfsmap_fill(meta_list, fsb, len: 1, EXT4_FMR_OWN_FS);
382 if (error)
383 return error;
384 fsb++;
385 }
386
387 /* Record the group descriptors. */
388 len = ext4_bg_num_gdb(sb, group: agno);
389 if (!len)
390 return 0;
391 error = ext4_getfsmap_fill(meta_list, fsb, len,
392 EXT4_FMR_OWN_GDT);
393 if (error)
394 return error;
395 fsb += len;
396
397 /* Reserved GDT blocks */
398 if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg) {
399 len = le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
400
401 /*
402 * mkfs.ext4 can set s_reserved_gdt_blocks as 0 in some cases,
403 * check for that.
404 */
405 if (!len)
406 return 0;
407
408 error = ext4_getfsmap_fill(meta_list, fsb, len,
409 EXT4_FMR_OWN_RESV_GDT);
410 if (error)
411 return error;
412 }
413
414 return 0;
415}
416
417/* Compare two fsmap items. */
418static int ext4_getfsmap_compare(void *priv,
419 const struct list_head *a,
420 const struct list_head *b)
421{
422 struct ext4_fsmap *fa;
423 struct ext4_fsmap *fb;
424
425 fa = container_of(a, struct ext4_fsmap, fmr_list);
426 fb = container_of(b, struct ext4_fsmap, fmr_list);
427 if (fa->fmr_physical < fb->fmr_physical)
428 return -1;
429 else if (fa->fmr_physical > fb->fmr_physical)
430 return 1;
431 return 0;
432}
433
434/* Merge adjacent extents of fixed metadata. */
435static void ext4_getfsmap_merge_fixed_metadata(struct list_head *meta_list)
436{
437 struct ext4_fsmap *p;
438 struct ext4_fsmap *prev = NULL;
439 struct ext4_fsmap *tmp;
440
441 list_for_each_entry_safe(p, tmp, meta_list, fmr_list) {
442 if (!prev) {
443 prev = p;
444 continue;
445 }
446
447 if (prev->fmr_owner == p->fmr_owner &&
448 prev->fmr_physical + prev->fmr_length == p->fmr_physical) {
449 prev->fmr_length += p->fmr_length;
450 list_del(entry: &p->fmr_list);
451 kfree(objp: p);
452 } else
453 prev = p;
454 }
455}
456
457/* Free a list of fixed metadata. */
458static void ext4_getfsmap_free_fixed_metadata(struct list_head *meta_list)
459{
460 struct ext4_fsmap *p;
461 struct ext4_fsmap *tmp;
462
463 list_for_each_entry_safe(p, tmp, meta_list, fmr_list) {
464 list_del(entry: &p->fmr_list);
465 kfree(objp: p);
466 }
467}
468
469/* Find all the fixed metadata in the filesystem. */
470static int ext4_getfsmap_find_fixed_metadata(struct super_block *sb,
471 struct list_head *meta_list)
472{
473 struct ext4_group_desc *gdp;
474 ext4_group_t agno;
475 int error;
476
477 INIT_LIST_HEAD(list: meta_list);
478
479 /* Collect everything. */
480 for (agno = 0; agno < EXT4_SB(sb)->s_groups_count; agno++) {
481 gdp = ext4_get_group_desc(sb, block_group: agno, NULL);
482 if (!gdp) {
483 error = -EFSCORRUPTED;
484 goto err;
485 }
486
487 /* Superblock & GDT */
488 error = ext4_getfsmap_find_sb(sb, agno, meta_list);
489 if (error)
490 goto err;
491
492 /* Block bitmap */
493 error = ext4_getfsmap_fill(meta_list,
494 fsb: ext4_block_bitmap(sb, bg: gdp), len: 1,
495 EXT4_FMR_OWN_BLKBM);
496 if (error)
497 goto err;
498
499 /* Inode bitmap */
500 error = ext4_getfsmap_fill(meta_list,
501 fsb: ext4_inode_bitmap(sb, bg: gdp), len: 1,
502 EXT4_FMR_OWN_INOBM);
503 if (error)
504 goto err;
505
506 /* Inodes */
507 error = ext4_getfsmap_fill(meta_list,
508 fsb: ext4_inode_table(sb, bg: gdp),
509 len: EXT4_SB(sb)->s_itb_per_group,
510 EXT4_FMR_OWN_INODES);
511 if (error)
512 goto err;
513 }
514
515 /* Sort the list */
516 list_sort(NULL, head: meta_list, cmp: ext4_getfsmap_compare);
517
518 /* Merge adjacent extents */
519 ext4_getfsmap_merge_fixed_metadata(meta_list);
520
521 return 0;
522err:
523 ext4_getfsmap_free_fixed_metadata(meta_list);
524 return error;
525}
526
527/* Execute a getfsmap query against the buddy bitmaps */
528static int ext4_getfsmap_datadev(struct super_block *sb,
529 struct ext4_fsmap *keys,
530 struct ext4_getfsmap_info *info)
531{
532 struct ext4_sb_info *sbi = EXT4_SB(sb);
533 ext4_fsblk_t start_fsb;
534 ext4_fsblk_t end_fsb;
535 ext4_fsblk_t bofs;
536 ext4_fsblk_t eofs;
537 ext4_group_t start_ag;
538 ext4_group_t end_ag;
539 ext4_grpblk_t first_cluster;
540 ext4_grpblk_t last_cluster;
541 struct ext4_fsmap irec;
542 int error = 0;
543
544 bofs = le32_to_cpu(sbi->s_es->s_first_data_block);
545 eofs = ext4_blocks_count(es: sbi->s_es);
546 if (keys[0].fmr_physical >= eofs)
547 return 0;
548 else if (keys[0].fmr_physical < bofs)
549 keys[0].fmr_physical = bofs;
550 if (keys[1].fmr_physical >= eofs)
551 keys[1].fmr_physical = eofs - 1;
552 if (keys[1].fmr_physical < keys[0].fmr_physical)
553 return 0;
554 start_fsb = keys[0].fmr_physical;
555 end_fsb = keys[1].fmr_physical;
556
557 /* Determine first and last group to examine based on start and end */
558 ext4_get_group_no_and_offset(sb, blocknr: start_fsb, blockgrpp: &start_ag, offsetp: &first_cluster);
559 ext4_get_group_no_and_offset(sb, blocknr: end_fsb, blockgrpp: &end_ag, offsetp: &last_cluster);
560
561 /*
562 * Convert the fsmap low/high keys to bg based keys. Initialize
563 * low to the fsmap low key and max out the high key to the end
564 * of the bg.
565 */
566 info->gfi_low = keys[0];
567 info->gfi_low.fmr_physical = EXT4_C2B(sbi, first_cluster);
568 info->gfi_low.fmr_length = 0;
569
570 memset(s: &info->gfi_high, c: 0xFF, n: sizeof(info->gfi_high));
571
572 /* Assemble a list of all the fixed-location metadata. */
573 error = ext4_getfsmap_find_fixed_metadata(sb, meta_list: &info->gfi_meta_list);
574 if (error)
575 goto err;
576
577 /* Query each bg */
578 for (info->gfi_agno = start_ag;
579 info->gfi_agno <= end_ag;
580 info->gfi_agno++) {
581 /*
582 * Set the bg high key from the fsmap high key if this
583 * is the last bg that we're querying.
584 */
585 if (info->gfi_agno == end_ag) {
586 info->gfi_high = keys[1];
587 info->gfi_high.fmr_physical = EXT4_C2B(sbi,
588 last_cluster);
589 info->gfi_high.fmr_length = 0;
590 }
591
592 trace_ext4_fsmap_low_key(sb, keydev: info->gfi_dev, agno: info->gfi_agno,
593 bno: info->gfi_low.fmr_physical,
594 len: info->gfi_low.fmr_length,
595 owner: info->gfi_low.fmr_owner);
596
597 trace_ext4_fsmap_high_key(sb, keydev: info->gfi_dev, agno: info->gfi_agno,
598 bno: info->gfi_high.fmr_physical,
599 len: info->gfi_high.fmr_length,
600 owner: info->gfi_high.fmr_owner);
601
602 error = ext4_mballoc_query_range(sb, agno: info->gfi_agno,
603 EXT4_B2C(sbi, info->gfi_low.fmr_physical),
604 EXT4_B2C(sbi, info->gfi_high.fmr_physical),
605 meta_formatter: ext4_getfsmap_meta_helper,
606 formatter: ext4_getfsmap_datadev_helper, priv: info);
607 if (error)
608 goto err;
609
610 /*
611 * Set the bg low key to the start of the bg prior to
612 * moving on to the next bg.
613 */
614 if (info->gfi_agno == start_ag)
615 memset(s: &info->gfi_low, c: 0, n: sizeof(info->gfi_low));
616 }
617
618 /* Do we have a retained free extent? */
619 if (info->gfi_lastfree.fmr_owner) {
620 error = ext4_getfsmap_helper(sb, info, rec: &info->gfi_lastfree);
621 if (error)
622 goto err;
623 }
624
625 /*
626 * The dummy record below will cause ext4_getfsmap_helper() to report
627 * any allocated blocks at the end of the range.
628 */
629 irec.fmr_device = 0;
630 irec.fmr_physical = end_fsb + 1;
631 irec.fmr_length = 0;
632 irec.fmr_owner = EXT4_FMR_OWN_FREE;
633 irec.fmr_flags = 0;
634
635 info->gfi_last = true;
636 error = ext4_getfsmap_helper(sb, info, rec: &irec);
637 if (error)
638 goto err;
639
640err:
641 ext4_getfsmap_free_fixed_metadata(meta_list: &info->gfi_meta_list);
642 return error;
643}
644
645/* Do we recognize the device? */
646static bool ext4_getfsmap_is_valid_device(struct super_block *sb,
647 struct ext4_fsmap *fm)
648{
649 if (fm->fmr_device == 0 || fm->fmr_device == UINT_MAX ||
650 fm->fmr_device == new_encode_dev(dev: sb->s_bdev->bd_dev))
651 return true;
652 if (EXT4_SB(sb)->s_journal_bdev_file &&
653 fm->fmr_device ==
654 new_encode_dev(dev: file_bdev(bdev_file: EXT4_SB(sb)->s_journal_bdev_file)->bd_dev))
655 return true;
656 return false;
657}
658
659/* Ensure that the low key is less than the high key. */
660static bool ext4_getfsmap_check_keys(struct ext4_fsmap *low_key,
661 struct ext4_fsmap *high_key)
662{
663 if (low_key->fmr_device > high_key->fmr_device)
664 return false;
665 if (low_key->fmr_device < high_key->fmr_device)
666 return true;
667
668 if (low_key->fmr_physical > high_key->fmr_physical)
669 return false;
670 if (low_key->fmr_physical < high_key->fmr_physical)
671 return true;
672
673 if (low_key->fmr_owner > high_key->fmr_owner)
674 return false;
675 if (low_key->fmr_owner < high_key->fmr_owner)
676 return true;
677
678 return false;
679}
680
681#define EXT4_GETFSMAP_DEVS 2
682/*
683 * Get filesystem's extents as described in head, and format for
684 * output. Calls formatter to fill the user's buffer until all
685 * extents are mapped, until the passed-in head->fmh_count slots have
686 * been filled, or until the formatter short-circuits the loop, if it
687 * is tracking filled-in extents on its own.
688 *
689 * Key to Confusion
690 * ----------------
691 * There are multiple levels of keys and counters at work here:
692 * _fsmap_head.fmh_keys -- low and high fsmap keys passed in;
693 * these reflect fs-wide block addrs.
694 * dkeys -- fmh_keys used to query each device;
695 * these are fmh_keys but w/ the low key
696 * bumped up by fmr_length.
697 * _getfsmap_info.gfi_next_fsblk-- next fs block we expect to see; this
698 * is how we detect gaps in the fsmap
699 * records and report them.
700 * _getfsmap_info.gfi_low/high -- per-bg low/high keys computed from
701 * dkeys; used to query the free space.
702 */
703int ext4_getfsmap(struct super_block *sb, struct ext4_fsmap_head *head,
704 ext4_fsmap_format_t formatter, void *arg)
705{
706 struct ext4_fsmap dkeys[2]; /* per-dev keys */
707 struct ext4_getfsmap_dev handlers[EXT4_GETFSMAP_DEVS];
708 struct ext4_getfsmap_info info = { NULL };
709 int i;
710 int error = 0;
711
712 if (head->fmh_iflags & ~FMH_IF_VALID)
713 return -EINVAL;
714 if (!ext4_getfsmap_is_valid_device(sb, fm: &head->fmh_keys[0]) ||
715 !ext4_getfsmap_is_valid_device(sb, fm: &head->fmh_keys[1]))
716 return -EINVAL;
717
718 head->fmh_entries = 0;
719
720 /* Set up our device handlers. */
721 memset(s: handlers, c: 0, n: sizeof(handlers));
722 handlers[0].gfd_dev = new_encode_dev(dev: sb->s_bdev->bd_dev);
723 handlers[0].gfd_fn = ext4_getfsmap_datadev;
724 if (EXT4_SB(sb)->s_journal_bdev_file) {
725 handlers[1].gfd_dev = new_encode_dev(
726 dev: file_bdev(bdev_file: EXT4_SB(sb)->s_journal_bdev_file)->bd_dev);
727 handlers[1].gfd_fn = ext4_getfsmap_logdev;
728 }
729
730 sort(base: handlers, EXT4_GETFSMAP_DEVS, size: sizeof(struct ext4_getfsmap_dev),
731 cmp_func: ext4_getfsmap_dev_compare, NULL);
732
733 /*
734 * To continue where we left off, we allow userspace to use the
735 * last mapping from a previous call as the low key of the next.
736 * This is identified by a non-zero length in the low key. We
737 * have to increment the low key in this scenario to ensure we
738 * don't return the same mapping again, and instead return the
739 * very next mapping.
740 *
741 * Bump the physical offset as there can be no other mapping for
742 * the same physical block range.
743 */
744 dkeys[0] = head->fmh_keys[0];
745 dkeys[0].fmr_physical += dkeys[0].fmr_length;
746 dkeys[0].fmr_owner = 0;
747 dkeys[0].fmr_length = 0;
748 memset(s: &dkeys[1], c: 0xFF, n: sizeof(struct ext4_fsmap));
749
750 if (!ext4_getfsmap_check_keys(low_key: dkeys, high_key: &head->fmh_keys[1]))
751 return -EINVAL;
752
753 info.gfi_next_fsblk = head->fmh_keys[0].fmr_physical +
754 head->fmh_keys[0].fmr_length;
755 info.gfi_formatter = formatter;
756 info.gfi_format_arg = arg;
757 info.gfi_head = head;
758
759 /* For each device we support... */
760 for (i = 0; i < EXT4_GETFSMAP_DEVS; i++) {
761 /* Is this device within the range the user asked for? */
762 if (!handlers[i].gfd_fn)
763 continue;
764 if (head->fmh_keys[0].fmr_device > handlers[i].gfd_dev)
765 continue;
766 if (head->fmh_keys[1].fmr_device < handlers[i].gfd_dev)
767 break;
768
769 /*
770 * If this device number matches the high key, we have
771 * to pass the high key to the handler to limit the
772 * query results. If the device number exceeds the
773 * low key, zero out the low key so that we get
774 * everything from the beginning.
775 */
776 if (handlers[i].gfd_dev == head->fmh_keys[1].fmr_device)
777 dkeys[1] = head->fmh_keys[1];
778 if (handlers[i].gfd_dev > head->fmh_keys[0].fmr_device)
779 memset(s: &dkeys[0], c: 0, n: sizeof(struct ext4_fsmap));
780
781 info.gfi_dev = handlers[i].gfd_dev;
782 info.gfi_last = false;
783 info.gfi_agno = -1;
784 error = handlers[i].gfd_fn(sb, dkeys, &info);
785 if (error)
786 break;
787 info.gfi_next_fsblk = 0;
788 }
789
790 head->fmh_oflags = FMH_OF_DEV_T;
791 return error;
792}
793