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Linux 6.13-rc7
[linux.git] / fs / ext4 / fsmap.c
blob383c6edea6dd31d855ae9e65519580fbc63ba756
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. */
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. */
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. */
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 */
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 */
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
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 static int ext4_getfsmap_meta_helper(struct super_block *sb,
189 ext4_group_t agno, ext4_grpblk_t start,
190 ext4_grpblk_t len, void *priv)
191 {
192 struct ext4_getfsmap_info *info = priv;
193 struct ext4_fsmap *p;
194 struct ext4_fsmap *tmp;
195 struct ext4_sb_info *sbi = EXT4_SB(sb);
196 ext4_fsblk_t fsb, fs_start, fs_end;
197 int error;
198
199 fs_start = fsb = (EXT4_C2B(sbi, start) +
200 ext4_group_first_block_no(sb, agno));
201 fs_end = fs_start + EXT4_C2B(sbi, len);
202
203 /* Return relevant extents from the meta_list */
204 list_for_each_entry_safe(p, tmp, &info->gfi_meta_list, fmr_list) {
205 if (p->fmr_physical < info->gfi_next_fsblk) {
206 list_del(&p->fmr_list);
207 kfree(p);
208 continue;
209 }
210 if (p->fmr_physical <= fs_start ||
211 p->fmr_physical + p->fmr_length <= fs_end) {
212 /* Emit the retained free extent record if present */
213 if (info->gfi_lastfree.fmr_owner) {
214 error = ext4_getfsmap_helper(sb, info,
215 &info->gfi_lastfree);
216 if (error)
217 return error;
218 info->gfi_lastfree.fmr_owner = 0;
219 }
220 error = ext4_getfsmap_helper(sb, info, p);
221 if (error)
222 return error;
223 fsb = p->fmr_physical + p->fmr_length;
224 if (info->gfi_next_fsblk < fsb)
225 info->gfi_next_fsblk = fsb;
226 list_del(&p->fmr_list);
227 kfree(p);
228 continue;
229 }
230 }
231 if (info->gfi_next_fsblk < fsb)
232 info->gfi_next_fsblk = fsb;
233
234 return 0;
235 }
236
237
238 /* Transform a blockgroup's free record into a fsmap */
239 static int ext4_getfsmap_datadev_helper(struct super_block *sb,
240 ext4_group_t agno, ext4_grpblk_t start,
241 ext4_grpblk_t len, void *priv)
242 {
243 struct ext4_fsmap irec;
244 struct ext4_getfsmap_info *info = priv;
245 struct ext4_fsmap *p;
246 struct ext4_fsmap *tmp;
247 struct ext4_sb_info *sbi = EXT4_SB(sb);
248 ext4_fsblk_t fsb;
249 ext4_fsblk_t fslen;
250 int error;
251
252 fsb = (EXT4_C2B(sbi, start) + ext4_group_first_block_no(sb, agno));
253 fslen = EXT4_C2B(sbi, len);
254
255 /* If the retained free extent record is set... */
256 if (info->gfi_lastfree.fmr_owner) {
257 /* ...and abuts this one, lengthen it and return. */
258 if (ext4_fsmap_next_pblk(&info->gfi_lastfree) == fsb) {
259 info->gfi_lastfree.fmr_length += fslen;
260 return 0;
261 }
262
263 /*
264 * There's a gap between the two free extents; emit the
265 * retained extent prior to merging the meta_list.
266 */
267 error = ext4_getfsmap_helper(sb, info, &info->gfi_lastfree);
268 if (error)
269 return error;
270 info->gfi_lastfree.fmr_owner = 0;
271 }
272
273 /* Merge in any relevant extents from the meta_list */
274 list_for_each_entry_safe(p, tmp, &info->gfi_meta_list, fmr_list) {
275 if (p->fmr_physical + p->fmr_length <= info->gfi_next_fsblk) {
276 list_del(&p->fmr_list);
277 kfree(p);
278 } else if (p->fmr_physical < fsb) {
279 error = ext4_getfsmap_helper(sb, info, p);
280 if (error)
281 return error;
282
283 list_del(&p->fmr_list);
284 kfree(p);
285 }
286 }
287
288 irec.fmr_device = 0;
289 irec.fmr_physical = fsb;
290 irec.fmr_length = fslen;
291 irec.fmr_owner = EXT4_FMR_OWN_FREE;
292 irec.fmr_flags = 0;
293
294 /* If this is a free extent at the end of a bg, buffer it. */
295 if (ext4_fsmap_next_pblk(&irec) ==
296 ext4_group_first_block_no(sb, agno + 1)) {
297 info->gfi_lastfree = irec;
298 return 0;
299 }
300
301 /* Otherwise, emit it */
302 return ext4_getfsmap_helper(sb, info, &irec);
303 }
304
305 /* Execute a getfsmap query against the log device. */
306 static int ext4_getfsmap_logdev(struct super_block *sb, struct ext4_fsmap *keys,
307 struct ext4_getfsmap_info *info)
308 {
309 journal_t *journal = EXT4_SB(sb)->s_journal;
310 struct ext4_fsmap irec;
311
312 /* Set up search keys */
313 info->gfi_low = keys[0];
314 info->gfi_low.fmr_length = 0;
315
316 memset(&info->gfi_high, 0xFF, sizeof(info->gfi_high));
317
318 trace_ext4_fsmap_low_key(sb, info->gfi_dev, 0,
319 info->gfi_low.fmr_physical,
320 info->gfi_low.fmr_length,
321 info->gfi_low.fmr_owner);
322
323 trace_ext4_fsmap_high_key(sb, info->gfi_dev, 0,
324 info->gfi_high.fmr_physical,
325 info->gfi_high.fmr_length,
326 info->gfi_high.fmr_owner);
327
328 if (keys[0].fmr_physical > 0)
329 return 0;
330
331 /* Fabricate an rmap entry for the external log device. */
332 irec.fmr_physical = journal->j_blk_offset;
333 irec.fmr_length = journal->j_total_len;
334 irec.fmr_owner = EXT4_FMR_OWN_LOG;
335 irec.fmr_flags = 0;
336
337 return ext4_getfsmap_helper(sb, info, &irec);
338 }
339
340 /* Helper to fill out an ext4_fsmap. */
341 static inline int ext4_getfsmap_fill(struct list_head *meta_list,
342 ext4_fsblk_t fsb, ext4_fsblk_t len,
343 uint64_t owner)
344 {
345 struct ext4_fsmap *fsm;
346
347 fsm = kmalloc(sizeof(*fsm), GFP_NOFS);
348 if (!fsm)
349 return -ENOMEM;
350 fsm->fmr_device = 0;
351 fsm->fmr_flags = 0;
352 fsm->fmr_physical = fsb;
353 fsm->fmr_owner = owner;
354 fsm->fmr_length = len;
355 list_add_tail(&fsm->fmr_list, meta_list);
356
357 return 0;
358 }
359
360 /*
361 * This function returns the number of file system metadata blocks at
362 * the beginning of a block group, including the reserved gdt blocks.
363 */
364 static unsigned int ext4_getfsmap_find_sb(struct super_block *sb,
365 ext4_group_t agno,
366 struct list_head *meta_list)
367 {
368 struct ext4_sb_info *sbi = EXT4_SB(sb);
369 ext4_fsblk_t fsb = ext4_group_first_block_no(sb, agno);
370 ext4_fsblk_t len;
371 unsigned long first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
372 unsigned long metagroup = agno / EXT4_DESC_PER_BLOCK(sb);
373 int error;
374
375 /* Record the superblock. */
376 if (ext4_bg_has_super(sb, agno)) {
377 error = ext4_getfsmap_fill(meta_list, fsb, 1, EXT4_FMR_OWN_FS);
378 if (error)
379 return error;
380 fsb++;
381 }
382
383 /* Record the group descriptors. */
384 len = ext4_bg_num_gdb(sb, agno);
385 if (!len)
386 return 0;
387 error = ext4_getfsmap_fill(meta_list, fsb, len,
388 EXT4_FMR_OWN_GDT);
389 if (error)
390 return error;
391 fsb += len;
392
393 /* Reserved GDT blocks */
394 if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg) {
395 len = le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
396 error = ext4_getfsmap_fill(meta_list, fsb, len,
397 EXT4_FMR_OWN_RESV_GDT);
398 if (error)
399 return error;
400 }
401
402 return 0;
403 }
404
405 /* Compare two fsmap items. */
406 static int ext4_getfsmap_compare(void *priv,
407 const struct list_head *a,
408 const struct list_head *b)
409 {
410 struct ext4_fsmap *fa;
411 struct ext4_fsmap *fb;
412
413 fa = container_of(a, struct ext4_fsmap, fmr_list);
414 fb = container_of(b, struct ext4_fsmap, fmr_list);
415 if (fa->fmr_physical < fb->fmr_physical)
416 return -1;
417 else if (fa->fmr_physical > fb->fmr_physical)
418 return 1;
419 return 0;
420 }
421
422 /* Merge adjacent extents of fixed metadata. */
423 static void ext4_getfsmap_merge_fixed_metadata(struct list_head *meta_list)
424 {
425 struct ext4_fsmap *p;
426 struct ext4_fsmap *prev = NULL;
427 struct ext4_fsmap *tmp;
428
429 list_for_each_entry_safe(p, tmp, meta_list, fmr_list) {
430 if (!prev) {
431 prev = p;
432 continue;
433 }
434
435 if (prev->fmr_owner == p->fmr_owner &&
436 prev->fmr_physical + prev->fmr_length == p->fmr_physical) {
437 prev->fmr_length += p->fmr_length;
438 list_del(&p->fmr_list);
439 kfree(p);
440 } else
441 prev = p;
442 }
443 }
444
445 /* Free a list of fixed metadata. */
446 static void ext4_getfsmap_free_fixed_metadata(struct list_head *meta_list)
447 {
448 struct ext4_fsmap *p;
449 struct ext4_fsmap *tmp;
450
451 list_for_each_entry_safe(p, tmp, meta_list, fmr_list) {
452 list_del(&p->fmr_list);
453 kfree(p);
454 }
455 }
456
457 /* Find all the fixed metadata in the filesystem. */
458 static int ext4_getfsmap_find_fixed_metadata(struct super_block *sb,
459 struct list_head *meta_list)
460 {
461 struct ext4_group_desc *gdp;
462 ext4_group_t agno;
463 int error;
464
465 INIT_LIST_HEAD(meta_list);
466
467 /* Collect everything. */
468 for (agno = 0; agno < EXT4_SB(sb)->s_groups_count; agno++) {
469 gdp = ext4_get_group_desc(sb, agno, NULL);
470 if (!gdp) {
471 error = -EFSCORRUPTED;
472 goto err;
473 }
474
475 /* Superblock & GDT */
476 error = ext4_getfsmap_find_sb(sb, agno, meta_list);
477 if (error)
478 goto err;
479
480 /* Block bitmap */
481 error = ext4_getfsmap_fill(meta_list,
482 ext4_block_bitmap(sb, gdp), 1,
483 EXT4_FMR_OWN_BLKBM);
484 if (error)
485 goto err;
486
487 /* Inode bitmap */
488 error = ext4_getfsmap_fill(meta_list,
489 ext4_inode_bitmap(sb, gdp), 1,
490 EXT4_FMR_OWN_INOBM);
491 if (error)
492 goto err;
493
494 /* Inodes */
495 error = ext4_getfsmap_fill(meta_list,
496 ext4_inode_table(sb, gdp),
497 EXT4_SB(sb)->s_itb_per_group,
498 EXT4_FMR_OWN_INODES);
499 if (error)
500 goto err;
501 }
502
503 /* Sort the list */
504 list_sort(NULL, meta_list, ext4_getfsmap_compare);
505
506 /* Merge adjacent extents */
507 ext4_getfsmap_merge_fixed_metadata(meta_list);
508
509 return 0;
510 err:
511 ext4_getfsmap_free_fixed_metadata(meta_list);
512 return error;
513 }
514
515 /* Execute a getfsmap query against the buddy bitmaps */
516 static int ext4_getfsmap_datadev(struct super_block *sb,
517 struct ext4_fsmap *keys,
518 struct ext4_getfsmap_info *info)
519 {
520 struct ext4_sb_info *sbi = EXT4_SB(sb);
521 ext4_fsblk_t start_fsb;
522 ext4_fsblk_t end_fsb;
523 ext4_fsblk_t bofs;
524 ext4_fsblk_t eofs;
525 ext4_group_t start_ag;
526 ext4_group_t end_ag;
527 ext4_grpblk_t first_cluster;
528 ext4_grpblk_t last_cluster;
529 int error = 0;
530
531 bofs = le32_to_cpu(sbi->s_es->s_first_data_block);
532 eofs = ext4_blocks_count(sbi->s_es);
533 if (keys[0].fmr_physical >= eofs)
534 return 0;
535 else if (keys[0].fmr_physical < bofs)
536 keys[0].fmr_physical = bofs;
537 if (keys[1].fmr_physical >= eofs)
538 keys[1].fmr_physical = eofs - 1;
539 if (keys[1].fmr_physical < keys[0].fmr_physical)
540 return 0;
541 start_fsb = keys[0].fmr_physical;
542 end_fsb = keys[1].fmr_physical;
543
544 /* Determine first and last group to examine based on start and end */
545 ext4_get_group_no_and_offset(sb, start_fsb, &start_ag, &first_cluster);
546 ext4_get_group_no_and_offset(sb, end_fsb, &end_ag, &last_cluster);
547
548 /*
549 * Convert the fsmap low/high keys to bg based keys. Initialize
550 * low to the fsmap low key and max out the high key to the end
551 * of the bg.
552 */
553 info->gfi_low = keys[0];
554 info->gfi_low.fmr_physical = EXT4_C2B(sbi, first_cluster);
555 info->gfi_low.fmr_length = 0;
556
557 memset(&info->gfi_high, 0xFF, sizeof(info->gfi_high));
558
559 /* Assemble a list of all the fixed-location metadata. */
560 error = ext4_getfsmap_find_fixed_metadata(sb, &info->gfi_meta_list);
561 if (error)
562 goto err;
563
564 /* Query each bg */
565 for (info->gfi_agno = start_ag;
566 info->gfi_agno <= end_ag;
567 info->gfi_agno++) {
568 /*
569 * Set the bg high key from the fsmap high key if this
570 * is the last bg that we're querying.
571 */
572 if (info->gfi_agno == end_ag) {
573 info->gfi_high = keys[1];
574 info->gfi_high.fmr_physical = EXT4_C2B(sbi,
575 last_cluster);
576 info->gfi_high.fmr_length = 0;
577 }
578
579 trace_ext4_fsmap_low_key(sb, info->gfi_dev, info->gfi_agno,
580 info->gfi_low.fmr_physical,
581 info->gfi_low.fmr_length,
582 info->gfi_low.fmr_owner);
583
584 trace_ext4_fsmap_high_key(sb, info->gfi_dev, info->gfi_agno,
585 info->gfi_high.fmr_physical,
586 info->gfi_high.fmr_length,
587 info->gfi_high.fmr_owner);
588
589 error = ext4_mballoc_query_range(sb, info->gfi_agno,
590 EXT4_B2C(sbi, info->gfi_low.fmr_physical),
591 EXT4_B2C(sbi, info->gfi_high.fmr_physical),
592 ext4_getfsmap_meta_helper,
593 ext4_getfsmap_datadev_helper, info);
594 if (error)
595 goto err;
596
597 /*
598 * Set the bg low key to the start of the bg prior to
599 * moving on to the next bg.
600 */
601 if (info->gfi_agno == start_ag)
602 memset(&info->gfi_low, 0, sizeof(info->gfi_low));
603 }
604
605 /* Do we have a retained free extent? */
606 if (info->gfi_lastfree.fmr_owner) {
607 error = ext4_getfsmap_helper(sb, info, &info->gfi_lastfree);
608 if (error)
609 goto err;
610 }
611
612 /* Report any gaps at the end of the bg */
613 info->gfi_last = true;
614 error = ext4_getfsmap_datadev_helper(sb, end_ag, last_cluster + 1,
615 0, info);
616 if (error)
617 goto err;
618
619 err:
620 ext4_getfsmap_free_fixed_metadata(&info->gfi_meta_list);
621 return error;
622 }
623
624 /* Do we recognize the device? */
625 static bool ext4_getfsmap_is_valid_device(struct super_block *sb,
626 struct ext4_fsmap *fm)
627 {
628 if (fm->fmr_device == 0 || fm->fmr_device == UINT_MAX ||
629 fm->fmr_device == new_encode_dev(sb->s_bdev->bd_dev))
630 return true;
631 if (EXT4_SB(sb)->s_journal_bdev_file &&
632 fm->fmr_device ==
633 new_encode_dev(file_bdev(EXT4_SB(sb)->s_journal_bdev_file)->bd_dev))
634 return true;
635 return false;
636 }
637
638 /* Ensure that the low key is less than the high key. */
639 static bool ext4_getfsmap_check_keys(struct ext4_fsmap *low_key,
640 struct ext4_fsmap *high_key)
641 {
642 if (low_key->fmr_device > high_key->fmr_device)
643 return false;
644 if (low_key->fmr_device < high_key->fmr_device)
645 return true;
646
647 if (low_key->fmr_physical > high_key->fmr_physical)
648 return false;
649 if (low_key->fmr_physical < high_key->fmr_physical)
650 return true;
651
652 if (low_key->fmr_owner > high_key->fmr_owner)
653 return false;
654 if (low_key->fmr_owner < high_key->fmr_owner)
655 return true;
656
657 return false;
658 }
659
660 #define EXT4_GETFSMAP_DEVS 2
661 /*
662 * Get filesystem's extents as described in head, and format for
663 * output. Calls formatter to fill the user's buffer until all
664 * extents are mapped, until the passed-in head->fmh_count slots have
665 * been filled, or until the formatter short-circuits the loop, if it
666 * is tracking filled-in extents on its own.
667 *
668 * Key to Confusion
669 * ----------------
670 * There are multiple levels of keys and counters at work here:
671 * _fsmap_head.fmh_keys -- low and high fsmap keys passed in;
672 * these reflect fs-wide block addrs.
673 * dkeys -- fmh_keys used to query each device;
674 * these are fmh_keys but w/ the low key
675 * bumped up by fmr_length.
676 * _getfsmap_info.gfi_next_fsblk-- next fs block we expect to see; this
677 * is how we detect gaps in the fsmap
678 * records and report them.
679 * _getfsmap_info.gfi_low/high -- per-bg low/high keys computed from
680 * dkeys; used to query the free space.
681 */
682 int ext4_getfsmap(struct super_block *sb, struct ext4_fsmap_head *head,
683 ext4_fsmap_format_t formatter, void *arg)
684 {
685 struct ext4_fsmap dkeys[2]; /* per-dev keys */
686 struct ext4_getfsmap_dev handlers[EXT4_GETFSMAP_DEVS];
687 struct ext4_getfsmap_info info = { NULL };
688 int i;
689 int error = 0;
690
691 if (head->fmh_iflags & ~FMH_IF_VALID)
692 return -EINVAL;
693 if (!ext4_getfsmap_is_valid_device(sb, &head->fmh_keys[0]) ||
694 !ext4_getfsmap_is_valid_device(sb, &head->fmh_keys[1]))
695 return -EINVAL;
696
697 head->fmh_entries = 0;
698
699 /* Set up our device handlers. */
700 memset(handlers, 0, sizeof(handlers));
701 handlers[0].gfd_dev = new_encode_dev(sb->s_bdev->bd_dev);
702 handlers[0].gfd_fn = ext4_getfsmap_datadev;
703 if (EXT4_SB(sb)->s_journal_bdev_file) {
704 handlers[1].gfd_dev = new_encode_dev(
705 file_bdev(EXT4_SB(sb)->s_journal_bdev_file)->bd_dev);
706 handlers[1].gfd_fn = ext4_getfsmap_logdev;
707 }
708
709 sort(handlers, EXT4_GETFSMAP_DEVS, sizeof(struct ext4_getfsmap_dev),
710 ext4_getfsmap_dev_compare, NULL);
711
712 /*
713 * To continue where we left off, we allow userspace to use the
714 * last mapping from a previous call as the low key of the next.
715 * This is identified by a non-zero length in the low key. We
716 * have to increment the low key in this scenario to ensure we
717 * don't return the same mapping again, and instead return the
718 * very next mapping.
719 *
720 * Bump the physical offset as there can be no other mapping for
721 * the same physical block range.
722 */
723 dkeys[0] = head->fmh_keys[0];
724 dkeys[0].fmr_physical += dkeys[0].fmr_length;
725 dkeys[0].fmr_owner = 0;
726 dkeys[0].fmr_length = 0;
727 memset(&dkeys[1], 0xFF, sizeof(struct ext4_fsmap));
728
729 if (!ext4_getfsmap_check_keys(dkeys, &head->fmh_keys[1]))
730 return -EINVAL;
731
732 info.gfi_next_fsblk = head->fmh_keys[0].fmr_physical +
733 head->fmh_keys[0].fmr_length;
734 info.gfi_formatter = formatter;
735 info.gfi_format_arg = arg;
736 info.gfi_head = head;
737
738 /* For each device we support... */
739 for (i = 0; i < EXT4_GETFSMAP_DEVS; i++) {
740 /* Is this device within the range the user asked for? */
741 if (!handlers[i].gfd_fn)
742 continue;
743 if (head->fmh_keys[0].fmr_device > handlers[i].gfd_dev)
744 continue;
745 if (head->fmh_keys[1].fmr_device < handlers[i].gfd_dev)
746 break;
747
748 /*
749 * If this device number matches the high key, we have
750 * to pass the high key to the handler to limit the
751 * query results. If the device number exceeds the
752 * low key, zero out the low key so that we get
753 * everything from the beginning.
754 */
755 if (handlers[i].gfd_dev == head->fmh_keys[1].fmr_device)
756 dkeys[1] = head->fmh_keys[1];
757 if (handlers[i].gfd_dev > head->fmh_keys[0].fmr_device)
758 memset(&dkeys[0], 0, sizeof(struct ext4_fsmap));
759
760 info.gfi_dev = handlers[i].gfd_dev;
761 info.gfi_last = false;
762 info.gfi_agno = -1;
763 error = handlers[i].gfd_fn(sb, dkeys, &info);
764 if (error)
765 break;
766 info.gfi_next_fsblk = 0;
767 }
768
769 head->fmh_oflags = FMH_OF_DEV_T;
770 return error;
771 }
Linux Kernel