1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (C) 2016 Oracle.  All Rights Reserved.
4  * Author: Darrick J. Wong <darrick.wong@oracle.com>
5  */
6 #include "xfs.h"
7 #include "xfs_fs.h"
8 #include "xfs_shared.h"
9 #include "xfs_format.h"
10 #include "xfs_log_format.h"
11 #include "xfs_trans_resv.h"
12 #include "xfs_mount.h"
13 #include "xfs_defer.h"
14 #include "xfs_btree.h"
15 #include "xfs_bmap.h"
16 #include "xfs_refcount_btree.h"
17 #include "xfs_alloc.h"
18 #include "xfs_errortag.h"
19 #include "xfs_error.h"
20 #include "xfs_trace.h"
21 #include "xfs_trans.h"
22 #include "xfs_bit.h"
23 #include "xfs_refcount.h"
24 #include "xfs_rmap.h"
25 #include "xfs_ag.h"
26 
27 struct kmem_cache	*xfs_refcount_intent_cache;
28 
29 /* Allowable refcount adjustment amounts. */
30 enum xfs_refc_adjust_op {
31 	XFS_REFCOUNT_ADJUST_INCREASE	= 1,
32 	XFS_REFCOUNT_ADJUST_DECREASE	= -1,
33 	XFS_REFCOUNT_ADJUST_COW_ALLOC	= 0,
34 	XFS_REFCOUNT_ADJUST_COW_FREE	= -1,
35 };
36 
37 STATIC int __xfs_refcount_cow_alloc(struct xfs_btree_cur *rcur,
38 		xfs_agblock_t agbno, xfs_extlen_t aglen);
39 STATIC int __xfs_refcount_cow_free(struct xfs_btree_cur *rcur,
40 		xfs_agblock_t agbno, xfs_extlen_t aglen);
41 
42 /*
43  * Look up the first record less than or equal to [bno, len] in the btree
44  * given by cur.
45  */
46 int
xfs_refcount_lookup_le(struct xfs_btree_cur * cur,enum xfs_refc_domain domain,xfs_agblock_t bno,int * stat)47 xfs_refcount_lookup_le(
48 	struct xfs_btree_cur	*cur,
49 	enum xfs_refc_domain	domain,
50 	xfs_agblock_t		bno,
51 	int			*stat)
52 {
53 	trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_ag.pag->pag_agno,
54 			xfs_refcount_encode_startblock(bno, domain),
55 			XFS_LOOKUP_LE);
56 	cur->bc_rec.rc.rc_startblock = bno;
57 	cur->bc_rec.rc.rc_blockcount = 0;
58 	cur->bc_rec.rc.rc_domain = domain;
59 	return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
60 }
61 
62 /*
63  * Look up the first record greater than or equal to [bno, len] in the btree
64  * given by cur.
65  */
66 int
xfs_refcount_lookup_ge(struct xfs_btree_cur * cur,enum xfs_refc_domain domain,xfs_agblock_t bno,int * stat)67 xfs_refcount_lookup_ge(
68 	struct xfs_btree_cur	*cur,
69 	enum xfs_refc_domain	domain,
70 	xfs_agblock_t		bno,
71 	int			*stat)
72 {
73 	trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_ag.pag->pag_agno,
74 			xfs_refcount_encode_startblock(bno, domain),
75 			XFS_LOOKUP_GE);
76 	cur->bc_rec.rc.rc_startblock = bno;
77 	cur->bc_rec.rc.rc_blockcount = 0;
78 	cur->bc_rec.rc.rc_domain = domain;
79 	return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
80 }
81 
82 /*
83  * Look up the first record equal to [bno, len] in the btree
84  * given by cur.
85  */
86 int
xfs_refcount_lookup_eq(struct xfs_btree_cur * cur,enum xfs_refc_domain domain,xfs_agblock_t bno,int * stat)87 xfs_refcount_lookup_eq(
88 	struct xfs_btree_cur	*cur,
89 	enum xfs_refc_domain	domain,
90 	xfs_agblock_t		bno,
91 	int			*stat)
92 {
93 	trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_ag.pag->pag_agno,
94 			xfs_refcount_encode_startblock(bno, domain),
95 			XFS_LOOKUP_LE);
96 	cur->bc_rec.rc.rc_startblock = bno;
97 	cur->bc_rec.rc.rc_blockcount = 0;
98 	cur->bc_rec.rc.rc_domain = domain;
99 	return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
100 }
101 
102 /* Convert on-disk record to in-core format. */
103 void
xfs_refcount_btrec_to_irec(const union xfs_btree_rec * rec,struct xfs_refcount_irec * irec)104 xfs_refcount_btrec_to_irec(
105 	const union xfs_btree_rec	*rec,
106 	struct xfs_refcount_irec	*irec)
107 {
108 	uint32_t			start;
109 
110 	start = be32_to_cpu(rec->refc.rc_startblock);
111 	if (start & XFS_REFC_COWFLAG) {
112 		start &= ~XFS_REFC_COWFLAG;
113 		irec->rc_domain = XFS_REFC_DOMAIN_COW;
114 	} else {
115 		irec->rc_domain = XFS_REFC_DOMAIN_SHARED;
116 	}
117 
118 	irec->rc_startblock = start;
119 	irec->rc_blockcount = be32_to_cpu(rec->refc.rc_blockcount);
120 	irec->rc_refcount = be32_to_cpu(rec->refc.rc_refcount);
121 }
122 
123 /*
124  * Get the data from the pointed-to record.
125  */
126 int
xfs_refcount_get_rec(struct xfs_btree_cur * cur,struct xfs_refcount_irec * irec,int * stat)127 xfs_refcount_get_rec(
128 	struct xfs_btree_cur		*cur,
129 	struct xfs_refcount_irec	*irec,
130 	int				*stat)
131 {
132 	struct xfs_mount		*mp = cur->bc_mp;
133 	struct xfs_perag		*pag = cur->bc_ag.pag;
134 	union xfs_btree_rec		*rec;
135 	int				error;
136 
137 	error = xfs_btree_get_rec(cur, &rec, stat);
138 	if (error || !*stat)
139 		return error;
140 
141 	xfs_refcount_btrec_to_irec(rec, irec);
142 	if (irec->rc_blockcount == 0 || irec->rc_blockcount > MAXREFCEXTLEN)
143 		goto out_bad_rec;
144 
145 	if (!xfs_refcount_check_domain(irec))
146 		goto out_bad_rec;
147 
148 	/* check for valid extent range, including overflow */
149 	if (!xfs_verify_agbext(pag, irec->rc_startblock, irec->rc_blockcount))
150 		goto out_bad_rec;
151 
152 	if (irec->rc_refcount == 0 || irec->rc_refcount > MAXREFCOUNT)
153 		goto out_bad_rec;
154 
155 	trace_xfs_refcount_get(cur->bc_mp, pag->pag_agno, irec);
156 	return 0;
157 
158 out_bad_rec:
159 	xfs_warn(mp,
160 		"Refcount BTree record corruption in AG %d detected!",
161 		pag->pag_agno);
162 	xfs_warn(mp,
163 		"Start block 0x%x, block count 0x%x, references 0x%x",
164 		irec->rc_startblock, irec->rc_blockcount, irec->rc_refcount);
165 	return -EFSCORRUPTED;
166 }
167 
168 /*
169  * Update the record referred to by cur to the value given
170  * by [bno, len, refcount].
171  * This either works (return 0) or gets an EFSCORRUPTED error.
172  */
173 STATIC int
xfs_refcount_update(struct xfs_btree_cur * cur,struct xfs_refcount_irec * irec)174 xfs_refcount_update(
175 	struct xfs_btree_cur		*cur,
176 	struct xfs_refcount_irec	*irec)
177 {
178 	union xfs_btree_rec	rec;
179 	uint32_t		start;
180 	int			error;
181 
182 	trace_xfs_refcount_update(cur->bc_mp, cur->bc_ag.pag->pag_agno, irec);
183 
184 	start = xfs_refcount_encode_startblock(irec->rc_startblock,
185 			irec->rc_domain);
186 	rec.refc.rc_startblock = cpu_to_be32(start);
187 	rec.refc.rc_blockcount = cpu_to_be32(irec->rc_blockcount);
188 	rec.refc.rc_refcount = cpu_to_be32(irec->rc_refcount);
189 
190 	error = xfs_btree_update(cur, &rec);
191 	if (error)
192 		trace_xfs_refcount_update_error(cur->bc_mp,
193 				cur->bc_ag.pag->pag_agno, error, _RET_IP_);
194 	return error;
195 }
196 
197 /*
198  * Insert the record referred to by cur to the value given
199  * by [bno, len, refcount].
200  * This either works (return 0) or gets an EFSCORRUPTED error.
201  */
202 int
xfs_refcount_insert(struct xfs_btree_cur * cur,struct xfs_refcount_irec * irec,int * i)203 xfs_refcount_insert(
204 	struct xfs_btree_cur		*cur,
205 	struct xfs_refcount_irec	*irec,
206 	int				*i)
207 {
208 	int				error;
209 
210 	trace_xfs_refcount_insert(cur->bc_mp, cur->bc_ag.pag->pag_agno, irec);
211 
212 	cur->bc_rec.rc.rc_startblock = irec->rc_startblock;
213 	cur->bc_rec.rc.rc_blockcount = irec->rc_blockcount;
214 	cur->bc_rec.rc.rc_refcount = irec->rc_refcount;
215 	cur->bc_rec.rc.rc_domain = irec->rc_domain;
216 
217 	error = xfs_btree_insert(cur, i);
218 	if (error)
219 		goto out_error;
220 	if (XFS_IS_CORRUPT(cur->bc_mp, *i != 1)) {
221 		error = -EFSCORRUPTED;
222 		goto out_error;
223 	}
224 
225 out_error:
226 	if (error)
227 		trace_xfs_refcount_insert_error(cur->bc_mp,
228 				cur->bc_ag.pag->pag_agno, error, _RET_IP_);
229 	return error;
230 }
231 
232 /*
233  * Remove the record referred to by cur, then set the pointer to the spot
234  * where the record could be re-inserted, in case we want to increment or
235  * decrement the cursor.
236  * This either works (return 0) or gets an EFSCORRUPTED error.
237  */
238 STATIC int
xfs_refcount_delete(struct xfs_btree_cur * cur,int * i)239 xfs_refcount_delete(
240 	struct xfs_btree_cur	*cur,
241 	int			*i)
242 {
243 	struct xfs_refcount_irec	irec;
244 	int			found_rec;
245 	int			error;
246 
247 	error = xfs_refcount_get_rec(cur, &irec, &found_rec);
248 	if (error)
249 		goto out_error;
250 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
251 		error = -EFSCORRUPTED;
252 		goto out_error;
253 	}
254 	trace_xfs_refcount_delete(cur->bc_mp, cur->bc_ag.pag->pag_agno, &irec);
255 	error = xfs_btree_delete(cur, i);
256 	if (XFS_IS_CORRUPT(cur->bc_mp, *i != 1)) {
257 		error = -EFSCORRUPTED;
258 		goto out_error;
259 	}
260 	if (error)
261 		goto out_error;
262 	error = xfs_refcount_lookup_ge(cur, irec.rc_domain, irec.rc_startblock,
263 			&found_rec);
264 out_error:
265 	if (error)
266 		trace_xfs_refcount_delete_error(cur->bc_mp,
267 				cur->bc_ag.pag->pag_agno, error, _RET_IP_);
268 	return error;
269 }
270 
271 /*
272  * Adjusting the Reference Count
273  *
274  * As stated elsewhere, the reference count btree (refcbt) stores
275  * >1 reference counts for extents of physical blocks.  In this
276  * operation, we're either raising or lowering the reference count of
277  * some subrange stored in the tree:
278  *
279  *      <------ adjustment range ------>
280  * ----+   +---+-----+ +--+--------+---------
281  *  2  |   | 3 |  4  | |17|   55   |   10
282  * ----+   +---+-----+ +--+--------+---------
283  * X axis is physical blocks number;
284  * reference counts are the numbers inside the rectangles
285  *
286  * The first thing we need to do is to ensure that there are no
287  * refcount extents crossing either boundary of the range to be
288  * adjusted.  For any extent that does cross a boundary, split it into
289  * two extents so that we can increment the refcount of one of the
290  * pieces later:
291  *
292  *      <------ adjustment range ------>
293  * ----+   +---+-----+ +--+--------+----+----
294  *  2  |   | 3 |  2  | |17|   55   | 10 | 10
295  * ----+   +---+-----+ +--+--------+----+----
296  *
297  * For this next step, let's assume that all the physical blocks in
298  * the adjustment range are mapped to a file and are therefore in use
299  * at least once.  Therefore, we can infer that any gap in the
300  * refcount tree within the adjustment range represents a physical
301  * extent with refcount == 1:
302  *
303  *      <------ adjustment range ------>
304  * ----+---+---+-----+-+--+--------+----+----
305  *  2  |"1"| 3 |  2  |1|17|   55   | 10 | 10
306  * ----+---+---+-----+-+--+--------+----+----
307  *      ^
308  *
309  * For each extent that falls within the interval range, figure out
310  * which extent is to the left or the right of that extent.  Now we
311  * have a left, current, and right extent.  If the new reference count
312  * of the center extent enables us to merge left, center, and right
313  * into one record covering all three, do so.  If the center extent is
314  * at the left end of the range, abuts the left extent, and its new
315  * reference count matches the left extent's record, then merge them.
316  * If the center extent is at the right end of the range, abuts the
317  * right extent, and the reference counts match, merge those.  In the
318  * example, we can left merge (assuming an increment operation):
319  *
320  *      <------ adjustment range ------>
321  * --------+---+-----+-+--+--------+----+----
322  *    2    | 3 |  2  |1|17|   55   | 10 | 10
323  * --------+---+-----+-+--+--------+----+----
324  *          ^
325  *
326  * For all other extents within the range, adjust the reference count
327  * or delete it if the refcount falls below 2.  If we were
328  * incrementing, the end result looks like this:
329  *
330  *      <------ adjustment range ------>
331  * --------+---+-----+-+--+--------+----+----
332  *    2    | 4 |  3  |2|18|   56   | 11 | 10
333  * --------+---+-----+-+--+--------+----+----
334  *
335  * The result of a decrement operation looks as such:
336  *
337  *      <------ adjustment range ------>
338  * ----+   +---+       +--+--------+----+----
339  *  2  |   | 2 |       |16|   54   |  9 | 10
340  * ----+   +---+       +--+--------+----+----
341  *      DDDD    111111DD
342  *
343  * The blocks marked "D" are freed; the blocks marked "1" are only
344  * referenced once and therefore the record is removed from the
345  * refcount btree.
346  */
347 
348 /* Next block after this extent. */
349 static inline xfs_agblock_t
xfs_refc_next(struct xfs_refcount_irec * rc)350 xfs_refc_next(
351 	struct xfs_refcount_irec	*rc)
352 {
353 	return rc->rc_startblock + rc->rc_blockcount;
354 }
355 
356 /*
357  * Split a refcount extent that crosses agbno.
358  */
359 STATIC int
xfs_refcount_split_extent(struct xfs_btree_cur * cur,enum xfs_refc_domain domain,xfs_agblock_t agbno,bool * shape_changed)360 xfs_refcount_split_extent(
361 	struct xfs_btree_cur		*cur,
362 	enum xfs_refc_domain		domain,
363 	xfs_agblock_t			agbno,
364 	bool				*shape_changed)
365 {
366 	struct xfs_refcount_irec	rcext, tmp;
367 	int				found_rec;
368 	int				error;
369 
370 	*shape_changed = false;
371 	error = xfs_refcount_lookup_le(cur, domain, agbno, &found_rec);
372 	if (error)
373 		goto out_error;
374 	if (!found_rec)
375 		return 0;
376 
377 	error = xfs_refcount_get_rec(cur, &rcext, &found_rec);
378 	if (error)
379 		goto out_error;
380 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
381 		error = -EFSCORRUPTED;
382 		goto out_error;
383 	}
384 	if (rcext.rc_domain != domain)
385 		return 0;
386 	if (rcext.rc_startblock == agbno || xfs_refc_next(&rcext) <= agbno)
387 		return 0;
388 
389 	*shape_changed = true;
390 	trace_xfs_refcount_split_extent(cur->bc_mp, cur->bc_ag.pag->pag_agno,
391 			&rcext, agbno);
392 
393 	/* Establish the right extent. */
394 	tmp = rcext;
395 	tmp.rc_startblock = agbno;
396 	tmp.rc_blockcount -= (agbno - rcext.rc_startblock);
397 	error = xfs_refcount_update(cur, &tmp);
398 	if (error)
399 		goto out_error;
400 
401 	/* Insert the left extent. */
402 	tmp = rcext;
403 	tmp.rc_blockcount = agbno - rcext.rc_startblock;
404 	error = xfs_refcount_insert(cur, &tmp, &found_rec);
405 	if (error)
406 		goto out_error;
407 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
408 		error = -EFSCORRUPTED;
409 		goto out_error;
410 	}
411 	return error;
412 
413 out_error:
414 	trace_xfs_refcount_split_extent_error(cur->bc_mp,
415 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
416 	return error;
417 }
418 
419 /*
420  * Merge the left, center, and right extents.
421  */
422 STATIC int
xfs_refcount_merge_center_extents(struct xfs_btree_cur * cur,struct xfs_refcount_irec * left,struct xfs_refcount_irec * center,struct xfs_refcount_irec * right,unsigned long long extlen,xfs_extlen_t * aglen)423 xfs_refcount_merge_center_extents(
424 	struct xfs_btree_cur		*cur,
425 	struct xfs_refcount_irec	*left,
426 	struct xfs_refcount_irec	*center,
427 	struct xfs_refcount_irec	*right,
428 	unsigned long long		extlen,
429 	xfs_extlen_t			*aglen)
430 {
431 	int				error;
432 	int				found_rec;
433 
434 	trace_xfs_refcount_merge_center_extents(cur->bc_mp,
435 			cur->bc_ag.pag->pag_agno, left, center, right);
436 
437 	ASSERT(left->rc_domain == center->rc_domain);
438 	ASSERT(right->rc_domain == center->rc_domain);
439 
440 	/*
441 	 * Make sure the center and right extents are not in the btree.
442 	 * If the center extent was synthesized, the first delete call
443 	 * removes the right extent and we skip the second deletion.
444 	 * If center and right were in the btree, then the first delete
445 	 * call removes the center and the second one removes the right
446 	 * extent.
447 	 */
448 	error = xfs_refcount_lookup_ge(cur, center->rc_domain,
449 			center->rc_startblock, &found_rec);
450 	if (error)
451 		goto out_error;
452 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
453 		error = -EFSCORRUPTED;
454 		goto out_error;
455 	}
456 
457 	error = xfs_refcount_delete(cur, &found_rec);
458 	if (error)
459 		goto out_error;
460 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
461 		error = -EFSCORRUPTED;
462 		goto out_error;
463 	}
464 
465 	if (center->rc_refcount > 1) {
466 		error = xfs_refcount_delete(cur, &found_rec);
467 		if (error)
468 			goto out_error;
469 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
470 			error = -EFSCORRUPTED;
471 			goto out_error;
472 		}
473 	}
474 
475 	/* Enlarge the left extent. */
476 	error = xfs_refcount_lookup_le(cur, left->rc_domain,
477 			left->rc_startblock, &found_rec);
478 	if (error)
479 		goto out_error;
480 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
481 		error = -EFSCORRUPTED;
482 		goto out_error;
483 	}
484 
485 	left->rc_blockcount = extlen;
486 	error = xfs_refcount_update(cur, left);
487 	if (error)
488 		goto out_error;
489 
490 	*aglen = 0;
491 	return error;
492 
493 out_error:
494 	trace_xfs_refcount_merge_center_extents_error(cur->bc_mp,
495 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
496 	return error;
497 }
498 
499 /*
500  * Merge with the left extent.
501  */
502 STATIC int
xfs_refcount_merge_left_extent(struct xfs_btree_cur * cur,struct xfs_refcount_irec * left,struct xfs_refcount_irec * cleft,xfs_agblock_t * agbno,xfs_extlen_t * aglen)503 xfs_refcount_merge_left_extent(
504 	struct xfs_btree_cur		*cur,
505 	struct xfs_refcount_irec	*left,
506 	struct xfs_refcount_irec	*cleft,
507 	xfs_agblock_t			*agbno,
508 	xfs_extlen_t			*aglen)
509 {
510 	int				error;
511 	int				found_rec;
512 
513 	trace_xfs_refcount_merge_left_extent(cur->bc_mp,
514 			cur->bc_ag.pag->pag_agno, left, cleft);
515 
516 	ASSERT(left->rc_domain == cleft->rc_domain);
517 
518 	/* If the extent at agbno (cleft) wasn't synthesized, remove it. */
519 	if (cleft->rc_refcount > 1) {
520 		error = xfs_refcount_lookup_le(cur, cleft->rc_domain,
521 				cleft->rc_startblock, &found_rec);
522 		if (error)
523 			goto out_error;
524 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
525 			error = -EFSCORRUPTED;
526 			goto out_error;
527 		}
528 
529 		error = xfs_refcount_delete(cur, &found_rec);
530 		if (error)
531 			goto out_error;
532 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
533 			error = -EFSCORRUPTED;
534 			goto out_error;
535 		}
536 	}
537 
538 	/* Enlarge the left extent. */
539 	error = xfs_refcount_lookup_le(cur, left->rc_domain,
540 			left->rc_startblock, &found_rec);
541 	if (error)
542 		goto out_error;
543 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
544 		error = -EFSCORRUPTED;
545 		goto out_error;
546 	}
547 
548 	left->rc_blockcount += cleft->rc_blockcount;
549 	error = xfs_refcount_update(cur, left);
550 	if (error)
551 		goto out_error;
552 
553 	*agbno += cleft->rc_blockcount;
554 	*aglen -= cleft->rc_blockcount;
555 	return error;
556 
557 out_error:
558 	trace_xfs_refcount_merge_left_extent_error(cur->bc_mp,
559 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
560 	return error;
561 }
562 
563 /*
564  * Merge with the right extent.
565  */
566 STATIC int
xfs_refcount_merge_right_extent(struct xfs_btree_cur * cur,struct xfs_refcount_irec * right,struct xfs_refcount_irec * cright,xfs_extlen_t * aglen)567 xfs_refcount_merge_right_extent(
568 	struct xfs_btree_cur		*cur,
569 	struct xfs_refcount_irec	*right,
570 	struct xfs_refcount_irec	*cright,
571 	xfs_extlen_t			*aglen)
572 {
573 	int				error;
574 	int				found_rec;
575 
576 	trace_xfs_refcount_merge_right_extent(cur->bc_mp,
577 			cur->bc_ag.pag->pag_agno, cright, right);
578 
579 	ASSERT(right->rc_domain == cright->rc_domain);
580 
581 	/*
582 	 * If the extent ending at agbno+aglen (cright) wasn't synthesized,
583 	 * remove it.
584 	 */
585 	if (cright->rc_refcount > 1) {
586 		error = xfs_refcount_lookup_le(cur, cright->rc_domain,
587 				cright->rc_startblock, &found_rec);
588 		if (error)
589 			goto out_error;
590 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
591 			error = -EFSCORRUPTED;
592 			goto out_error;
593 		}
594 
595 		error = xfs_refcount_delete(cur, &found_rec);
596 		if (error)
597 			goto out_error;
598 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
599 			error = -EFSCORRUPTED;
600 			goto out_error;
601 		}
602 	}
603 
604 	/* Enlarge the right extent. */
605 	error = xfs_refcount_lookup_le(cur, right->rc_domain,
606 			right->rc_startblock, &found_rec);
607 	if (error)
608 		goto out_error;
609 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
610 		error = -EFSCORRUPTED;
611 		goto out_error;
612 	}
613 
614 	right->rc_startblock -= cright->rc_blockcount;
615 	right->rc_blockcount += cright->rc_blockcount;
616 	error = xfs_refcount_update(cur, right);
617 	if (error)
618 		goto out_error;
619 
620 	*aglen -= cright->rc_blockcount;
621 	return error;
622 
623 out_error:
624 	trace_xfs_refcount_merge_right_extent_error(cur->bc_mp,
625 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
626 	return error;
627 }
628 
629 /*
630  * Find the left extent and the one after it (cleft).  This function assumes
631  * that we've already split any extent crossing agbno.
632  */
633 STATIC int
xfs_refcount_find_left_extents(struct xfs_btree_cur * cur,struct xfs_refcount_irec * left,struct xfs_refcount_irec * cleft,enum xfs_refc_domain domain,xfs_agblock_t agbno,xfs_extlen_t aglen)634 xfs_refcount_find_left_extents(
635 	struct xfs_btree_cur		*cur,
636 	struct xfs_refcount_irec	*left,
637 	struct xfs_refcount_irec	*cleft,
638 	enum xfs_refc_domain		domain,
639 	xfs_agblock_t			agbno,
640 	xfs_extlen_t			aglen)
641 {
642 	struct xfs_refcount_irec	tmp;
643 	int				error;
644 	int				found_rec;
645 
646 	left->rc_startblock = cleft->rc_startblock = NULLAGBLOCK;
647 	error = xfs_refcount_lookup_le(cur, domain, agbno - 1, &found_rec);
648 	if (error)
649 		goto out_error;
650 	if (!found_rec)
651 		return 0;
652 
653 	error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
654 	if (error)
655 		goto out_error;
656 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
657 		error = -EFSCORRUPTED;
658 		goto out_error;
659 	}
660 
661 	if (tmp.rc_domain != domain)
662 		return 0;
663 	if (xfs_refc_next(&tmp) != agbno)
664 		return 0;
665 	/* We have a left extent; retrieve (or invent) the next right one */
666 	*left = tmp;
667 
668 	error = xfs_btree_increment(cur, 0, &found_rec);
669 	if (error)
670 		goto out_error;
671 	if (found_rec) {
672 		error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
673 		if (error)
674 			goto out_error;
675 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
676 			error = -EFSCORRUPTED;
677 			goto out_error;
678 		}
679 
680 		if (tmp.rc_domain != domain)
681 			goto not_found;
682 
683 		/* if tmp starts at the end of our range, just use that */
684 		if (tmp.rc_startblock == agbno)
685 			*cleft = tmp;
686 		else {
687 			/*
688 			 * There's a gap in the refcntbt at the start of the
689 			 * range we're interested in (refcount == 1) so
690 			 * synthesize the implied extent and pass it back.
691 			 * We assume here that the agbno/aglen range was
692 			 * passed in from a data fork extent mapping and
693 			 * therefore is allocated to exactly one owner.
694 			 */
695 			cleft->rc_startblock = agbno;
696 			cleft->rc_blockcount = min(aglen,
697 					tmp.rc_startblock - agbno);
698 			cleft->rc_refcount = 1;
699 			cleft->rc_domain = domain;
700 		}
701 	} else {
702 not_found:
703 		/*
704 		 * No extents, so pretend that there's one covering the whole
705 		 * range.
706 		 */
707 		cleft->rc_startblock = agbno;
708 		cleft->rc_blockcount = aglen;
709 		cleft->rc_refcount = 1;
710 		cleft->rc_domain = domain;
711 	}
712 	trace_xfs_refcount_find_left_extent(cur->bc_mp, cur->bc_ag.pag->pag_agno,
713 			left, cleft, agbno);
714 	return error;
715 
716 out_error:
717 	trace_xfs_refcount_find_left_extent_error(cur->bc_mp,
718 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
719 	return error;
720 }
721 
722 /*
723  * Find the right extent and the one before it (cright).  This function
724  * assumes that we've already split any extents crossing agbno + aglen.
725  */
726 STATIC int
xfs_refcount_find_right_extents(struct xfs_btree_cur * cur,struct xfs_refcount_irec * right,struct xfs_refcount_irec * cright,enum xfs_refc_domain domain,xfs_agblock_t agbno,xfs_extlen_t aglen)727 xfs_refcount_find_right_extents(
728 	struct xfs_btree_cur		*cur,
729 	struct xfs_refcount_irec	*right,
730 	struct xfs_refcount_irec	*cright,
731 	enum xfs_refc_domain		domain,
732 	xfs_agblock_t			agbno,
733 	xfs_extlen_t			aglen)
734 {
735 	struct xfs_refcount_irec	tmp;
736 	int				error;
737 	int				found_rec;
738 
739 	right->rc_startblock = cright->rc_startblock = NULLAGBLOCK;
740 	error = xfs_refcount_lookup_ge(cur, domain, agbno + aglen, &found_rec);
741 	if (error)
742 		goto out_error;
743 	if (!found_rec)
744 		return 0;
745 
746 	error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
747 	if (error)
748 		goto out_error;
749 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
750 		error = -EFSCORRUPTED;
751 		goto out_error;
752 	}
753 
754 	if (tmp.rc_domain != domain)
755 		return 0;
756 	if (tmp.rc_startblock != agbno + aglen)
757 		return 0;
758 	/* We have a right extent; retrieve (or invent) the next left one */
759 	*right = tmp;
760 
761 	error = xfs_btree_decrement(cur, 0, &found_rec);
762 	if (error)
763 		goto out_error;
764 	if (found_rec) {
765 		error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
766 		if (error)
767 			goto out_error;
768 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
769 			error = -EFSCORRUPTED;
770 			goto out_error;
771 		}
772 
773 		if (tmp.rc_domain != domain)
774 			goto not_found;
775 
776 		/* if tmp ends at the end of our range, just use that */
777 		if (xfs_refc_next(&tmp) == agbno + aglen)
778 			*cright = tmp;
779 		else {
780 			/*
781 			 * There's a gap in the refcntbt at the end of the
782 			 * range we're interested in (refcount == 1) so
783 			 * create the implied extent and pass it back.
784 			 * We assume here that the agbno/aglen range was
785 			 * passed in from a data fork extent mapping and
786 			 * therefore is allocated to exactly one owner.
787 			 */
788 			cright->rc_startblock = max(agbno, xfs_refc_next(&tmp));
789 			cright->rc_blockcount = right->rc_startblock -
790 					cright->rc_startblock;
791 			cright->rc_refcount = 1;
792 			cright->rc_domain = domain;
793 		}
794 	} else {
795 not_found:
796 		/*
797 		 * No extents, so pretend that there's one covering the whole
798 		 * range.
799 		 */
800 		cright->rc_startblock = agbno;
801 		cright->rc_blockcount = aglen;
802 		cright->rc_refcount = 1;
803 		cright->rc_domain = domain;
804 	}
805 	trace_xfs_refcount_find_right_extent(cur->bc_mp, cur->bc_ag.pag->pag_agno,
806 			cright, right, agbno + aglen);
807 	return error;
808 
809 out_error:
810 	trace_xfs_refcount_find_right_extent_error(cur->bc_mp,
811 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
812 	return error;
813 }
814 
815 /* Is this extent valid? */
816 static inline bool
xfs_refc_valid(struct xfs_refcount_irec * rc)817 xfs_refc_valid(
818 	struct xfs_refcount_irec	*rc)
819 {
820 	return rc->rc_startblock != NULLAGBLOCK;
821 }
822 
823 /*
824  * Try to merge with any extents on the boundaries of the adjustment range.
825  */
826 STATIC int
xfs_refcount_merge_extents(struct xfs_btree_cur * cur,enum xfs_refc_domain domain,xfs_agblock_t * agbno,xfs_extlen_t * aglen,enum xfs_refc_adjust_op adjust,bool * shape_changed)827 xfs_refcount_merge_extents(
828 	struct xfs_btree_cur	*cur,
829 	enum xfs_refc_domain	domain,
830 	xfs_agblock_t		*agbno,
831 	xfs_extlen_t		*aglen,
832 	enum xfs_refc_adjust_op adjust,
833 	bool			*shape_changed)
834 {
835 	struct xfs_refcount_irec	left = {0}, cleft = {0};
836 	struct xfs_refcount_irec	cright = {0}, right = {0};
837 	int				error;
838 	unsigned long long		ulen;
839 	bool				cequal;
840 
841 	*shape_changed = false;
842 	/*
843 	 * Find the extent just below agbno [left], just above agbno [cleft],
844 	 * just below (agbno + aglen) [cright], and just above (agbno + aglen)
845 	 * [right].
846 	 */
847 	error = xfs_refcount_find_left_extents(cur, &left, &cleft, domain,
848 			*agbno, *aglen);
849 	if (error)
850 		return error;
851 	error = xfs_refcount_find_right_extents(cur, &right, &cright, domain,
852 			*agbno, *aglen);
853 	if (error)
854 		return error;
855 
856 	/* No left or right extent to merge; exit. */
857 	if (!xfs_refc_valid(&left) && !xfs_refc_valid(&right))
858 		return 0;
859 
860 	cequal = (cleft.rc_startblock == cright.rc_startblock) &&
861 		 (cleft.rc_blockcount == cright.rc_blockcount);
862 
863 	/* Try to merge left, cleft, and right.  cleft must == cright. */
864 	ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount +
865 			right.rc_blockcount;
866 	if (xfs_refc_valid(&left) && xfs_refc_valid(&right) &&
867 	    xfs_refc_valid(&cleft) && xfs_refc_valid(&cright) && cequal &&
868 	    left.rc_refcount == cleft.rc_refcount + adjust &&
869 	    right.rc_refcount == cleft.rc_refcount + adjust &&
870 	    ulen < MAXREFCEXTLEN) {
871 		*shape_changed = true;
872 		return xfs_refcount_merge_center_extents(cur, &left, &cleft,
873 				&right, ulen, aglen);
874 	}
875 
876 	/* Try to merge left and cleft. */
877 	ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount;
878 	if (xfs_refc_valid(&left) && xfs_refc_valid(&cleft) &&
879 	    left.rc_refcount == cleft.rc_refcount + adjust &&
880 	    ulen < MAXREFCEXTLEN) {
881 		*shape_changed = true;
882 		error = xfs_refcount_merge_left_extent(cur, &left, &cleft,
883 				agbno, aglen);
884 		if (error)
885 			return error;
886 
887 		/*
888 		 * If we just merged left + cleft and cleft == cright,
889 		 * we no longer have a cright to merge with right.  We're done.
890 		 */
891 		if (cequal)
892 			return 0;
893 	}
894 
895 	/* Try to merge cright and right. */
896 	ulen = (unsigned long long)right.rc_blockcount + cright.rc_blockcount;
897 	if (xfs_refc_valid(&right) && xfs_refc_valid(&cright) &&
898 	    right.rc_refcount == cright.rc_refcount + adjust &&
899 	    ulen < MAXREFCEXTLEN) {
900 		*shape_changed = true;
901 		return xfs_refcount_merge_right_extent(cur, &right, &cright,
902 				aglen);
903 	}
904 
905 	return 0;
906 }
907 
908 /*
909  * XXX: This is a pretty hand-wavy estimate.  The penalty for guessing
910  * true incorrectly is a shutdown FS; the penalty for guessing false
911  * incorrectly is more transaction rolls than might be necessary.
912  * Be conservative here.
913  */
914 static bool
xfs_refcount_still_have_space(struct xfs_btree_cur * cur)915 xfs_refcount_still_have_space(
916 	struct xfs_btree_cur		*cur)
917 {
918 	unsigned long			overhead;
919 
920 	/*
921 	 * Worst case estimate: full splits of the free space and rmap btrees
922 	 * to handle each of the shape changes to the refcount btree.
923 	 */
924 	overhead = xfs_allocfree_block_count(cur->bc_mp,
925 				cur->bc_ag.refc.shape_changes);
926 	overhead += cur->bc_mp->m_refc_maxlevels;
927 	overhead *= cur->bc_mp->m_sb.sb_blocksize;
928 
929 	/*
930 	 * Only allow 2 refcount extent updates per transaction if the
931 	 * refcount continue update "error" has been injected.
932 	 */
933 	if (cur->bc_ag.refc.nr_ops > 2 &&
934 	    XFS_TEST_ERROR(false, cur->bc_mp,
935 			XFS_ERRTAG_REFCOUNT_CONTINUE_UPDATE))
936 		return false;
937 
938 	if (cur->bc_ag.refc.nr_ops == 0)
939 		return true;
940 	else if (overhead > cur->bc_tp->t_log_res)
941 		return false;
942 	return  cur->bc_tp->t_log_res - overhead >
943 		cur->bc_ag.refc.nr_ops * XFS_REFCOUNT_ITEM_OVERHEAD;
944 }
945 
946 /*
947  * Adjust the refcounts of middle extents.  At this point we should have
948  * split extents that crossed the adjustment range; merged with adjacent
949  * extents; and updated agbno/aglen to reflect the merges.  Therefore,
950  * all we have to do is update the extents inside [agbno, agbno + aglen].
951  */
952 STATIC int
xfs_refcount_adjust_extents(struct xfs_btree_cur * cur,xfs_agblock_t * agbno,xfs_extlen_t * aglen,enum xfs_refc_adjust_op adj)953 xfs_refcount_adjust_extents(
954 	struct xfs_btree_cur	*cur,
955 	xfs_agblock_t		*agbno,
956 	xfs_extlen_t		*aglen,
957 	enum xfs_refc_adjust_op	adj)
958 {
959 	struct xfs_refcount_irec	ext, tmp;
960 	int				error;
961 	int				found_rec, found_tmp;
962 	xfs_fsblock_t			fsbno;
963 
964 	/* Merging did all the work already. */
965 	if (*aglen == 0)
966 		return 0;
967 
968 	error = xfs_refcount_lookup_ge(cur, XFS_REFC_DOMAIN_SHARED, *agbno,
969 			&found_rec);
970 	if (error)
971 		goto out_error;
972 
973 	while (*aglen > 0 && xfs_refcount_still_have_space(cur)) {
974 		error = xfs_refcount_get_rec(cur, &ext, &found_rec);
975 		if (error)
976 			goto out_error;
977 		if (!found_rec || ext.rc_domain != XFS_REFC_DOMAIN_SHARED) {
978 			ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
979 			ext.rc_blockcount = 0;
980 			ext.rc_refcount = 0;
981 			ext.rc_domain = XFS_REFC_DOMAIN_SHARED;
982 		}
983 
984 		/*
985 		 * Deal with a hole in the refcount tree; if a file maps to
986 		 * these blocks and there's no refcountbt record, pretend that
987 		 * there is one with refcount == 1.
988 		 */
989 		if (ext.rc_startblock != *agbno) {
990 			tmp.rc_startblock = *agbno;
991 			tmp.rc_blockcount = min(*aglen,
992 					ext.rc_startblock - *agbno);
993 			tmp.rc_refcount = 1 + adj;
994 			tmp.rc_domain = XFS_REFC_DOMAIN_SHARED;
995 
996 			trace_xfs_refcount_modify_extent(cur->bc_mp,
997 					cur->bc_ag.pag->pag_agno, &tmp);
998 
999 			/*
1000 			 * Either cover the hole (increment) or
1001 			 * delete the range (decrement).
1002 			 */
1003 			cur->bc_ag.refc.nr_ops++;
1004 			if (tmp.rc_refcount) {
1005 				error = xfs_refcount_insert(cur, &tmp,
1006 						&found_tmp);
1007 				if (error)
1008 					goto out_error;
1009 				if (XFS_IS_CORRUPT(cur->bc_mp,
1010 						   found_tmp != 1)) {
1011 					error = -EFSCORRUPTED;
1012 					goto out_error;
1013 				}
1014 			} else {
1015 				fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
1016 						cur->bc_ag.pag->pag_agno,
1017 						tmp.rc_startblock);
1018 				xfs_free_extent_later(cur->bc_tp, fsbno,
1019 						  tmp.rc_blockcount, NULL);
1020 			}
1021 
1022 			(*agbno) += tmp.rc_blockcount;
1023 			(*aglen) -= tmp.rc_blockcount;
1024 
1025 			/* Stop if there's nothing left to modify */
1026 			if (*aglen == 0 || !xfs_refcount_still_have_space(cur))
1027 				break;
1028 
1029 			/* Move the cursor to the start of ext. */
1030 			error = xfs_refcount_lookup_ge(cur,
1031 					XFS_REFC_DOMAIN_SHARED, *agbno,
1032 					&found_rec);
1033 			if (error)
1034 				goto out_error;
1035 		}
1036 
1037 		/*
1038 		 * A previous step trimmed agbno/aglen such that the end of the
1039 		 * range would not be in the middle of the record.  If this is
1040 		 * no longer the case, something is seriously wrong with the
1041 		 * btree.  Make sure we never feed the synthesized record into
1042 		 * the processing loop below.
1043 		 */
1044 		if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_blockcount == 0) ||
1045 		    XFS_IS_CORRUPT(cur->bc_mp, ext.rc_blockcount > *aglen)) {
1046 			error = -EFSCORRUPTED;
1047 			goto out_error;
1048 		}
1049 
1050 		/*
1051 		 * Adjust the reference count and either update the tree
1052 		 * (incr) or free the blocks (decr).
1053 		 */
1054 		if (ext.rc_refcount == MAXREFCOUNT)
1055 			goto skip;
1056 		ext.rc_refcount += adj;
1057 		trace_xfs_refcount_modify_extent(cur->bc_mp,
1058 				cur->bc_ag.pag->pag_agno, &ext);
1059 		cur->bc_ag.refc.nr_ops++;
1060 		if (ext.rc_refcount > 1) {
1061 			error = xfs_refcount_update(cur, &ext);
1062 			if (error)
1063 				goto out_error;
1064 		} else if (ext.rc_refcount == 1) {
1065 			error = xfs_refcount_delete(cur, &found_rec);
1066 			if (error)
1067 				goto out_error;
1068 			if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
1069 				error = -EFSCORRUPTED;
1070 				goto out_error;
1071 			}
1072 			goto advloop;
1073 		} else {
1074 			fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
1075 					cur->bc_ag.pag->pag_agno,
1076 					ext.rc_startblock);
1077 			xfs_free_extent_later(cur->bc_tp, fsbno,
1078 					ext.rc_blockcount, NULL);
1079 		}
1080 
1081 skip:
1082 		error = xfs_btree_increment(cur, 0, &found_rec);
1083 		if (error)
1084 			goto out_error;
1085 
1086 advloop:
1087 		(*agbno) += ext.rc_blockcount;
1088 		(*aglen) -= ext.rc_blockcount;
1089 	}
1090 
1091 	return error;
1092 out_error:
1093 	trace_xfs_refcount_modify_extent_error(cur->bc_mp,
1094 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
1095 	return error;
1096 }
1097 
1098 /* Adjust the reference count of a range of AG blocks. */
1099 STATIC int
xfs_refcount_adjust(struct xfs_btree_cur * cur,xfs_agblock_t agbno,xfs_extlen_t aglen,xfs_agblock_t * new_agbno,xfs_extlen_t * new_aglen,enum xfs_refc_adjust_op adj)1100 xfs_refcount_adjust(
1101 	struct xfs_btree_cur	*cur,
1102 	xfs_agblock_t		agbno,
1103 	xfs_extlen_t		aglen,
1104 	xfs_agblock_t		*new_agbno,
1105 	xfs_extlen_t		*new_aglen,
1106 	enum xfs_refc_adjust_op	adj)
1107 {
1108 	bool			shape_changed;
1109 	int			shape_changes = 0;
1110 	int			error;
1111 
1112 	*new_agbno = agbno;
1113 	*new_aglen = aglen;
1114 	if (adj == XFS_REFCOUNT_ADJUST_INCREASE)
1115 		trace_xfs_refcount_increase(cur->bc_mp, cur->bc_ag.pag->pag_agno,
1116 				agbno, aglen);
1117 	else
1118 		trace_xfs_refcount_decrease(cur->bc_mp, cur->bc_ag.pag->pag_agno,
1119 				agbno, aglen);
1120 
1121 	/*
1122 	 * Ensure that no rcextents cross the boundary of the adjustment range.
1123 	 */
1124 	error = xfs_refcount_split_extent(cur, XFS_REFC_DOMAIN_SHARED,
1125 			agbno, &shape_changed);
1126 	if (error)
1127 		goto out_error;
1128 	if (shape_changed)
1129 		shape_changes++;
1130 
1131 	error = xfs_refcount_split_extent(cur, XFS_REFC_DOMAIN_SHARED,
1132 			agbno + aglen, &shape_changed);
1133 	if (error)
1134 		goto out_error;
1135 	if (shape_changed)
1136 		shape_changes++;
1137 
1138 	/*
1139 	 * Try to merge with the left or right extents of the range.
1140 	 */
1141 	error = xfs_refcount_merge_extents(cur, XFS_REFC_DOMAIN_SHARED,
1142 			new_agbno, new_aglen, adj, &shape_changed);
1143 	if (error)
1144 		goto out_error;
1145 	if (shape_changed)
1146 		shape_changes++;
1147 	if (shape_changes)
1148 		cur->bc_ag.refc.shape_changes++;
1149 
1150 	/* Now that we've taken care of the ends, adjust the middle extents */
1151 	error = xfs_refcount_adjust_extents(cur, new_agbno, new_aglen, adj);
1152 	if (error)
1153 		goto out_error;
1154 
1155 	return 0;
1156 
1157 out_error:
1158 	trace_xfs_refcount_adjust_error(cur->bc_mp, cur->bc_ag.pag->pag_agno,
1159 			error, _RET_IP_);
1160 	return error;
1161 }
1162 
1163 /* Clean up after calling xfs_refcount_finish_one. */
1164 void
xfs_refcount_finish_one_cleanup(struct xfs_trans * tp,struct xfs_btree_cur * rcur,int error)1165 xfs_refcount_finish_one_cleanup(
1166 	struct xfs_trans	*tp,
1167 	struct xfs_btree_cur	*rcur,
1168 	int			error)
1169 {
1170 	struct xfs_buf		*agbp;
1171 
1172 	if (rcur == NULL)
1173 		return;
1174 	agbp = rcur->bc_ag.agbp;
1175 	xfs_btree_del_cursor(rcur, error);
1176 	if (error)
1177 		xfs_trans_brelse(tp, agbp);
1178 }
1179 
1180 /*
1181  * Set up a continuation a deferred refcount operation by updating the intent.
1182  * Checks to make sure we're not going to run off the end of the AG.
1183  */
1184 static inline int
xfs_refcount_continue_op(struct xfs_btree_cur * cur,xfs_fsblock_t startblock,xfs_agblock_t new_agbno,xfs_extlen_t new_len,xfs_fsblock_t * new_fsbno)1185 xfs_refcount_continue_op(
1186 	struct xfs_btree_cur		*cur,
1187 	xfs_fsblock_t			startblock,
1188 	xfs_agblock_t			new_agbno,
1189 	xfs_extlen_t			new_len,
1190 	xfs_fsblock_t			*new_fsbno)
1191 {
1192 	struct xfs_mount		*mp = cur->bc_mp;
1193 	struct xfs_perag		*pag = cur->bc_ag.pag;
1194 
1195 	if (XFS_IS_CORRUPT(mp, !xfs_verify_agbext(pag, new_agbno, new_len)))
1196 		return -EFSCORRUPTED;
1197 
1198 	*new_fsbno = XFS_AGB_TO_FSB(mp, pag->pag_agno, new_agbno);
1199 
1200 	ASSERT(xfs_verify_fsbext(mp, *new_fsbno, new_len));
1201 	ASSERT(pag->pag_agno == XFS_FSB_TO_AGNO(mp, *new_fsbno));
1202 
1203 	return 0;
1204 }
1205 
1206 /*
1207  * Process one of the deferred refcount operations.  We pass back the
1208  * btree cursor to maintain our lock on the btree between calls.
1209  * This saves time and eliminates a buffer deadlock between the
1210  * superblock and the AGF because we'll always grab them in the same
1211  * order.
1212  */
1213 int
xfs_refcount_finish_one(struct xfs_trans * tp,enum xfs_refcount_intent_type type,xfs_fsblock_t startblock,xfs_extlen_t blockcount,xfs_fsblock_t * new_fsb,xfs_extlen_t * new_len,struct xfs_btree_cur ** pcur)1214 xfs_refcount_finish_one(
1215 	struct xfs_trans		*tp,
1216 	enum xfs_refcount_intent_type	type,
1217 	xfs_fsblock_t			startblock,
1218 	xfs_extlen_t			blockcount,
1219 	xfs_fsblock_t			*new_fsb,
1220 	xfs_extlen_t			*new_len,
1221 	struct xfs_btree_cur		**pcur)
1222 {
1223 	struct xfs_mount		*mp = tp->t_mountp;
1224 	struct xfs_btree_cur		*rcur;
1225 	struct xfs_buf			*agbp = NULL;
1226 	int				error = 0;
1227 	xfs_agblock_t			bno;
1228 	xfs_agblock_t			new_agbno;
1229 	unsigned long			nr_ops = 0;
1230 	int				shape_changes = 0;
1231 	struct xfs_perag		*pag;
1232 
1233 	pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, startblock));
1234 	bno = XFS_FSB_TO_AGBNO(mp, startblock);
1235 
1236 	trace_xfs_refcount_deferred(mp, XFS_FSB_TO_AGNO(mp, startblock),
1237 			type, XFS_FSB_TO_AGBNO(mp, startblock),
1238 			blockcount);
1239 
1240 	if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_REFCOUNT_FINISH_ONE)) {
1241 		error = -EIO;
1242 		goto out_drop;
1243 	}
1244 
1245 	/*
1246 	 * If we haven't gotten a cursor or the cursor AG doesn't match
1247 	 * the startblock, get one now.
1248 	 */
1249 	rcur = *pcur;
1250 	if (rcur != NULL && rcur->bc_ag.pag != pag) {
1251 		nr_ops = rcur->bc_ag.refc.nr_ops;
1252 		shape_changes = rcur->bc_ag.refc.shape_changes;
1253 		xfs_refcount_finish_one_cleanup(tp, rcur, 0);
1254 		rcur = NULL;
1255 		*pcur = NULL;
1256 	}
1257 	if (rcur == NULL) {
1258 		error = xfs_alloc_read_agf(pag, tp, XFS_ALLOC_FLAG_FREEING,
1259 				&agbp);
1260 		if (error)
1261 			goto out_drop;
1262 
1263 		rcur = xfs_refcountbt_init_cursor(mp, tp, agbp, pag);
1264 		rcur->bc_ag.refc.nr_ops = nr_ops;
1265 		rcur->bc_ag.refc.shape_changes = shape_changes;
1266 	}
1267 	*pcur = rcur;
1268 
1269 	switch (type) {
1270 	case XFS_REFCOUNT_INCREASE:
1271 		error = xfs_refcount_adjust(rcur, bno, blockcount, &new_agbno,
1272 				new_len, XFS_REFCOUNT_ADJUST_INCREASE);
1273 		if (error)
1274 			goto out_drop;
1275 		if (*new_len > 0)
1276 			error = xfs_refcount_continue_op(rcur, startblock,
1277 					new_agbno, *new_len, new_fsb);
1278 		break;
1279 	case XFS_REFCOUNT_DECREASE:
1280 		error = xfs_refcount_adjust(rcur, bno, blockcount, &new_agbno,
1281 				new_len, XFS_REFCOUNT_ADJUST_DECREASE);
1282 		if (error)
1283 			goto out_drop;
1284 		if (*new_len > 0)
1285 			error = xfs_refcount_continue_op(rcur, startblock,
1286 					new_agbno, *new_len, new_fsb);
1287 		break;
1288 	case XFS_REFCOUNT_ALLOC_COW:
1289 		*new_fsb = startblock + blockcount;
1290 		*new_len = 0;
1291 		error = __xfs_refcount_cow_alloc(rcur, bno, blockcount);
1292 		break;
1293 	case XFS_REFCOUNT_FREE_COW:
1294 		*new_fsb = startblock + blockcount;
1295 		*new_len = 0;
1296 		error = __xfs_refcount_cow_free(rcur, bno, blockcount);
1297 		break;
1298 	default:
1299 		ASSERT(0);
1300 		error = -EFSCORRUPTED;
1301 	}
1302 	if (!error && *new_len > 0)
1303 		trace_xfs_refcount_finish_one_leftover(mp, pag->pag_agno, type,
1304 				bno, blockcount, new_agbno, *new_len);
1305 out_drop:
1306 	xfs_perag_put(pag);
1307 	return error;
1308 }
1309 
1310 /*
1311  * Record a refcount intent for later processing.
1312  */
1313 static void
__xfs_refcount_add(struct xfs_trans * tp,enum xfs_refcount_intent_type type,xfs_fsblock_t startblock,xfs_extlen_t blockcount)1314 __xfs_refcount_add(
1315 	struct xfs_trans		*tp,
1316 	enum xfs_refcount_intent_type	type,
1317 	xfs_fsblock_t			startblock,
1318 	xfs_extlen_t			blockcount)
1319 {
1320 	struct xfs_refcount_intent	*ri;
1321 
1322 	trace_xfs_refcount_defer(tp->t_mountp,
1323 			XFS_FSB_TO_AGNO(tp->t_mountp, startblock),
1324 			type, XFS_FSB_TO_AGBNO(tp->t_mountp, startblock),
1325 			blockcount);
1326 
1327 	ri = kmem_cache_alloc(xfs_refcount_intent_cache,
1328 			GFP_NOFS | __GFP_NOFAIL);
1329 	INIT_LIST_HEAD(&ri->ri_list);
1330 	ri->ri_type = type;
1331 	ri->ri_startblock = startblock;
1332 	ri->ri_blockcount = blockcount;
1333 
1334 	xfs_defer_add(tp, XFS_DEFER_OPS_TYPE_REFCOUNT, &ri->ri_list);
1335 }
1336 
1337 /*
1338  * Increase the reference count of the blocks backing a file's extent.
1339  */
1340 void
xfs_refcount_increase_extent(struct xfs_trans * tp,struct xfs_bmbt_irec * PREV)1341 xfs_refcount_increase_extent(
1342 	struct xfs_trans		*tp,
1343 	struct xfs_bmbt_irec		*PREV)
1344 {
1345 	if (!xfs_has_reflink(tp->t_mountp))
1346 		return;
1347 
1348 	__xfs_refcount_add(tp, XFS_REFCOUNT_INCREASE, PREV->br_startblock,
1349 			PREV->br_blockcount);
1350 }
1351 
1352 /*
1353  * Decrease the reference count of the blocks backing a file's extent.
1354  */
1355 void
xfs_refcount_decrease_extent(struct xfs_trans * tp,struct xfs_bmbt_irec * PREV)1356 xfs_refcount_decrease_extent(
1357 	struct xfs_trans		*tp,
1358 	struct xfs_bmbt_irec		*PREV)
1359 {
1360 	if (!xfs_has_reflink(tp->t_mountp))
1361 		return;
1362 
1363 	__xfs_refcount_add(tp, XFS_REFCOUNT_DECREASE, PREV->br_startblock,
1364 			PREV->br_blockcount);
1365 }
1366 
1367 /*
1368  * Given an AG extent, find the lowest-numbered run of shared blocks
1369  * within that range and return the range in fbno/flen.  If
1370  * find_end_of_shared is set, return the longest contiguous extent of
1371  * shared blocks; if not, just return the first extent we find.  If no
1372  * shared blocks are found, fbno and flen will be set to NULLAGBLOCK
1373  * and 0, respectively.
1374  */
1375 int
xfs_refcount_find_shared(struct xfs_btree_cur * cur,xfs_agblock_t agbno,xfs_extlen_t aglen,xfs_agblock_t * fbno,xfs_extlen_t * flen,bool find_end_of_shared)1376 xfs_refcount_find_shared(
1377 	struct xfs_btree_cur		*cur,
1378 	xfs_agblock_t			agbno,
1379 	xfs_extlen_t			aglen,
1380 	xfs_agblock_t			*fbno,
1381 	xfs_extlen_t			*flen,
1382 	bool				find_end_of_shared)
1383 {
1384 	struct xfs_refcount_irec	tmp;
1385 	int				i;
1386 	int				have;
1387 	int				error;
1388 
1389 	trace_xfs_refcount_find_shared(cur->bc_mp, cur->bc_ag.pag->pag_agno,
1390 			agbno, aglen);
1391 
1392 	/* By default, skip the whole range */
1393 	*fbno = NULLAGBLOCK;
1394 	*flen = 0;
1395 
1396 	/* Try to find a refcount extent that crosses the start */
1397 	error = xfs_refcount_lookup_le(cur, XFS_REFC_DOMAIN_SHARED, agbno,
1398 			&have);
1399 	if (error)
1400 		goto out_error;
1401 	if (!have) {
1402 		/* No left extent, look at the next one */
1403 		error = xfs_btree_increment(cur, 0, &have);
1404 		if (error)
1405 			goto out_error;
1406 		if (!have)
1407 			goto done;
1408 	}
1409 	error = xfs_refcount_get_rec(cur, &tmp, &i);
1410 	if (error)
1411 		goto out_error;
1412 	if (XFS_IS_CORRUPT(cur->bc_mp, i != 1)) {
1413 		error = -EFSCORRUPTED;
1414 		goto out_error;
1415 	}
1416 	if (tmp.rc_domain != XFS_REFC_DOMAIN_SHARED)
1417 		goto done;
1418 
1419 	/* If the extent ends before the start, look at the next one */
1420 	if (tmp.rc_startblock + tmp.rc_blockcount <= agbno) {
1421 		error = xfs_btree_increment(cur, 0, &have);
1422 		if (error)
1423 			goto out_error;
1424 		if (!have)
1425 			goto done;
1426 		error = xfs_refcount_get_rec(cur, &tmp, &i);
1427 		if (error)
1428 			goto out_error;
1429 		if (XFS_IS_CORRUPT(cur->bc_mp, i != 1)) {
1430 			error = -EFSCORRUPTED;
1431 			goto out_error;
1432 		}
1433 		if (tmp.rc_domain != XFS_REFC_DOMAIN_SHARED)
1434 			goto done;
1435 	}
1436 
1437 	/* If the extent starts after the range we want, bail out */
1438 	if (tmp.rc_startblock >= agbno + aglen)
1439 		goto done;
1440 
1441 	/* We found the start of a shared extent! */
1442 	if (tmp.rc_startblock < agbno) {
1443 		tmp.rc_blockcount -= (agbno - tmp.rc_startblock);
1444 		tmp.rc_startblock = agbno;
1445 	}
1446 
1447 	*fbno = tmp.rc_startblock;
1448 	*flen = min(tmp.rc_blockcount, agbno + aglen - *fbno);
1449 	if (!find_end_of_shared)
1450 		goto done;
1451 
1452 	/* Otherwise, find the end of this shared extent */
1453 	while (*fbno + *flen < agbno + aglen) {
1454 		error = xfs_btree_increment(cur, 0, &have);
1455 		if (error)
1456 			goto out_error;
1457 		if (!have)
1458 			break;
1459 		error = xfs_refcount_get_rec(cur, &tmp, &i);
1460 		if (error)
1461 			goto out_error;
1462 		if (XFS_IS_CORRUPT(cur->bc_mp, i != 1)) {
1463 			error = -EFSCORRUPTED;
1464 			goto out_error;
1465 		}
1466 		if (tmp.rc_domain != XFS_REFC_DOMAIN_SHARED ||
1467 		    tmp.rc_startblock >= agbno + aglen ||
1468 		    tmp.rc_startblock != *fbno + *flen)
1469 			break;
1470 		*flen = min(*flen + tmp.rc_blockcount, agbno + aglen - *fbno);
1471 	}
1472 
1473 done:
1474 	trace_xfs_refcount_find_shared_result(cur->bc_mp,
1475 			cur->bc_ag.pag->pag_agno, *fbno, *flen);
1476 
1477 out_error:
1478 	if (error)
1479 		trace_xfs_refcount_find_shared_error(cur->bc_mp,
1480 				cur->bc_ag.pag->pag_agno, error, _RET_IP_);
1481 	return error;
1482 }
1483 
1484 /*
1485  * Recovering CoW Blocks After a Crash
1486  *
1487  * Due to the way that the copy on write mechanism works, there's a window of
1488  * opportunity in which we can lose track of allocated blocks during a crash.
1489  * Because CoW uses delayed allocation in the in-core CoW fork, writeback
1490  * causes blocks to be allocated and stored in the CoW fork.  The blocks are
1491  * no longer in the free space btree but are not otherwise recorded anywhere
1492  * until the write completes and the blocks are mapped into the file.  A crash
1493  * in between allocation and remapping results in the replacement blocks being
1494  * lost.  This situation is exacerbated by the CoW extent size hint because
1495  * allocations can hang around for long time.
1496  *
1497  * However, there is a place where we can record these allocations before they
1498  * become mappings -- the reference count btree.  The btree does not record
1499  * extents with refcount == 1, so we can record allocations with a refcount of
1500  * 1.  Blocks being used for CoW writeout cannot be shared, so there should be
1501  * no conflict with shared block records.  These mappings should be created
1502  * when we allocate blocks to the CoW fork and deleted when they're removed
1503  * from the CoW fork.
1504  *
1505  * Minor nit: records for in-progress CoW allocations and records for shared
1506  * extents must never be merged, to preserve the property that (except for CoW
1507  * allocations) there are no refcount btree entries with refcount == 1.  The
1508  * only time this could potentially happen is when unsharing a block that's
1509  * adjacent to CoW allocations, so we must be careful to avoid this.
1510  *
1511  * At mount time we recover lost CoW allocations by searching the refcount
1512  * btree for these refcount == 1 mappings.  These represent CoW allocations
1513  * that were in progress at the time the filesystem went down, so we can free
1514  * them to get the space back.
1515  *
1516  * This mechanism is superior to creating EFIs for unmapped CoW extents for
1517  * several reasons -- first, EFIs pin the tail of the log and would have to be
1518  * periodically relogged to avoid filling up the log.  Second, CoW completions
1519  * will have to file an EFD and create new EFIs for whatever remains in the
1520  * CoW fork; this partially takes care of (1) but extent-size reservations
1521  * will have to periodically relog even if there's no writeout in progress.
1522  * This can happen if the CoW extent size hint is set, which you really want.
1523  * Third, EFIs cannot currently be automatically relogged into newer
1524  * transactions to advance the log tail.  Fourth, stuffing the log full of
1525  * EFIs places an upper bound on the number of CoW allocations that can be
1526  * held filesystem-wide at any given time.  Recording them in the refcount
1527  * btree doesn't require us to maintain any state in memory and doesn't pin
1528  * the log.
1529  */
1530 /*
1531  * Adjust the refcounts of CoW allocations.  These allocations are "magic"
1532  * in that they're not referenced anywhere else in the filesystem, so we
1533  * stash them in the refcount btree with a refcount of 1 until either file
1534  * remapping (or CoW cancellation) happens.
1535  */
1536 STATIC int
xfs_refcount_adjust_cow_extents(struct xfs_btree_cur * cur,xfs_agblock_t agbno,xfs_extlen_t aglen,enum xfs_refc_adjust_op adj)1537 xfs_refcount_adjust_cow_extents(
1538 	struct xfs_btree_cur	*cur,
1539 	xfs_agblock_t		agbno,
1540 	xfs_extlen_t		aglen,
1541 	enum xfs_refc_adjust_op	adj)
1542 {
1543 	struct xfs_refcount_irec	ext, tmp;
1544 	int				error;
1545 	int				found_rec, found_tmp;
1546 
1547 	if (aglen == 0)
1548 		return 0;
1549 
1550 	/* Find any overlapping refcount records */
1551 	error = xfs_refcount_lookup_ge(cur, XFS_REFC_DOMAIN_COW, agbno,
1552 			&found_rec);
1553 	if (error)
1554 		goto out_error;
1555 	error = xfs_refcount_get_rec(cur, &ext, &found_rec);
1556 	if (error)
1557 		goto out_error;
1558 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec &&
1559 				ext.rc_domain != XFS_REFC_DOMAIN_COW)) {
1560 		error = -EFSCORRUPTED;
1561 		goto out_error;
1562 	}
1563 	if (!found_rec) {
1564 		ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
1565 		ext.rc_blockcount = 0;
1566 		ext.rc_refcount = 0;
1567 		ext.rc_domain = XFS_REFC_DOMAIN_COW;
1568 	}
1569 
1570 	switch (adj) {
1571 	case XFS_REFCOUNT_ADJUST_COW_ALLOC:
1572 		/* Adding a CoW reservation, there should be nothing here. */
1573 		if (XFS_IS_CORRUPT(cur->bc_mp,
1574 				   agbno + aglen > ext.rc_startblock)) {
1575 			error = -EFSCORRUPTED;
1576 			goto out_error;
1577 		}
1578 
1579 		tmp.rc_startblock = agbno;
1580 		tmp.rc_blockcount = aglen;
1581 		tmp.rc_refcount = 1;
1582 		tmp.rc_domain = XFS_REFC_DOMAIN_COW;
1583 
1584 		trace_xfs_refcount_modify_extent(cur->bc_mp,
1585 				cur->bc_ag.pag->pag_agno, &tmp);
1586 
1587 		error = xfs_refcount_insert(cur, &tmp,
1588 				&found_tmp);
1589 		if (error)
1590 			goto out_error;
1591 		if (XFS_IS_CORRUPT(cur->bc_mp, found_tmp != 1)) {
1592 			error = -EFSCORRUPTED;
1593 			goto out_error;
1594 		}
1595 		break;
1596 	case XFS_REFCOUNT_ADJUST_COW_FREE:
1597 		/* Removing a CoW reservation, there should be one extent. */
1598 		if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_startblock != agbno)) {
1599 			error = -EFSCORRUPTED;
1600 			goto out_error;
1601 		}
1602 		if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_blockcount != aglen)) {
1603 			error = -EFSCORRUPTED;
1604 			goto out_error;
1605 		}
1606 		if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_refcount != 1)) {
1607 			error = -EFSCORRUPTED;
1608 			goto out_error;
1609 		}
1610 
1611 		ext.rc_refcount = 0;
1612 		trace_xfs_refcount_modify_extent(cur->bc_mp,
1613 				cur->bc_ag.pag->pag_agno, &ext);
1614 		error = xfs_refcount_delete(cur, &found_rec);
1615 		if (error)
1616 			goto out_error;
1617 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
1618 			error = -EFSCORRUPTED;
1619 			goto out_error;
1620 		}
1621 		break;
1622 	default:
1623 		ASSERT(0);
1624 	}
1625 
1626 	return error;
1627 out_error:
1628 	trace_xfs_refcount_modify_extent_error(cur->bc_mp,
1629 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
1630 	return error;
1631 }
1632 
1633 /*
1634  * Add or remove refcount btree entries for CoW reservations.
1635  */
1636 STATIC int
xfs_refcount_adjust_cow(struct xfs_btree_cur * cur,xfs_agblock_t agbno,xfs_extlen_t aglen,enum xfs_refc_adjust_op adj)1637 xfs_refcount_adjust_cow(
1638 	struct xfs_btree_cur	*cur,
1639 	xfs_agblock_t		agbno,
1640 	xfs_extlen_t		aglen,
1641 	enum xfs_refc_adjust_op	adj)
1642 {
1643 	bool			shape_changed;
1644 	int			error;
1645 
1646 	/*
1647 	 * Ensure that no rcextents cross the boundary of the adjustment range.
1648 	 */
1649 	error = xfs_refcount_split_extent(cur, XFS_REFC_DOMAIN_COW,
1650 			agbno, &shape_changed);
1651 	if (error)
1652 		goto out_error;
1653 
1654 	error = xfs_refcount_split_extent(cur, XFS_REFC_DOMAIN_COW,
1655 			agbno + aglen, &shape_changed);
1656 	if (error)
1657 		goto out_error;
1658 
1659 	/*
1660 	 * Try to merge with the left or right extents of the range.
1661 	 */
1662 	error = xfs_refcount_merge_extents(cur, XFS_REFC_DOMAIN_COW, &agbno,
1663 			&aglen, adj, &shape_changed);
1664 	if (error)
1665 		goto out_error;
1666 
1667 	/* Now that we've taken care of the ends, adjust the middle extents */
1668 	error = xfs_refcount_adjust_cow_extents(cur, agbno, aglen, adj);
1669 	if (error)
1670 		goto out_error;
1671 
1672 	return 0;
1673 
1674 out_error:
1675 	trace_xfs_refcount_adjust_cow_error(cur->bc_mp, cur->bc_ag.pag->pag_agno,
1676 			error, _RET_IP_);
1677 	return error;
1678 }
1679 
1680 /*
1681  * Record a CoW allocation in the refcount btree.
1682  */
1683 STATIC int
__xfs_refcount_cow_alloc(struct xfs_btree_cur * rcur,xfs_agblock_t agbno,xfs_extlen_t aglen)1684 __xfs_refcount_cow_alloc(
1685 	struct xfs_btree_cur	*rcur,
1686 	xfs_agblock_t		agbno,
1687 	xfs_extlen_t		aglen)
1688 {
1689 	trace_xfs_refcount_cow_increase(rcur->bc_mp, rcur->bc_ag.pag->pag_agno,
1690 			agbno, aglen);
1691 
1692 	/* Add refcount btree reservation */
1693 	return xfs_refcount_adjust_cow(rcur, agbno, aglen,
1694 			XFS_REFCOUNT_ADJUST_COW_ALLOC);
1695 }
1696 
1697 /*
1698  * Remove a CoW allocation from the refcount btree.
1699  */
1700 STATIC int
__xfs_refcount_cow_free(struct xfs_btree_cur * rcur,xfs_agblock_t agbno,xfs_extlen_t aglen)1701 __xfs_refcount_cow_free(
1702 	struct xfs_btree_cur	*rcur,
1703 	xfs_agblock_t		agbno,
1704 	xfs_extlen_t		aglen)
1705 {
1706 	trace_xfs_refcount_cow_decrease(rcur->bc_mp, rcur->bc_ag.pag->pag_agno,
1707 			agbno, aglen);
1708 
1709 	/* Remove refcount btree reservation */
1710 	return xfs_refcount_adjust_cow(rcur, agbno, aglen,
1711 			XFS_REFCOUNT_ADJUST_COW_FREE);
1712 }
1713 
1714 /* Record a CoW staging extent in the refcount btree. */
1715 void
xfs_refcount_alloc_cow_extent(struct xfs_trans * tp,xfs_fsblock_t fsb,xfs_extlen_t len)1716 xfs_refcount_alloc_cow_extent(
1717 	struct xfs_trans		*tp,
1718 	xfs_fsblock_t			fsb,
1719 	xfs_extlen_t			len)
1720 {
1721 	struct xfs_mount		*mp = tp->t_mountp;
1722 
1723 	if (!xfs_has_reflink(mp))
1724 		return;
1725 
1726 	__xfs_refcount_add(tp, XFS_REFCOUNT_ALLOC_COW, fsb, len);
1727 
1728 	/* Add rmap entry */
1729 	xfs_rmap_alloc_extent(tp, XFS_FSB_TO_AGNO(mp, fsb),
1730 			XFS_FSB_TO_AGBNO(mp, fsb), len, XFS_RMAP_OWN_COW);
1731 }
1732 
1733 /* Forget a CoW staging event in the refcount btree. */
1734 void
xfs_refcount_free_cow_extent(struct xfs_trans * tp,xfs_fsblock_t fsb,xfs_extlen_t len)1735 xfs_refcount_free_cow_extent(
1736 	struct xfs_trans		*tp,
1737 	xfs_fsblock_t			fsb,
1738 	xfs_extlen_t			len)
1739 {
1740 	struct xfs_mount		*mp = tp->t_mountp;
1741 
1742 	if (!xfs_has_reflink(mp))
1743 		return;
1744 
1745 	/* Remove rmap entry */
1746 	xfs_rmap_free_extent(tp, XFS_FSB_TO_AGNO(mp, fsb),
1747 			XFS_FSB_TO_AGBNO(mp, fsb), len, XFS_RMAP_OWN_COW);
1748 	__xfs_refcount_add(tp, XFS_REFCOUNT_FREE_COW, fsb, len);
1749 }
1750 
1751 struct xfs_refcount_recovery {
1752 	struct list_head		rr_list;
1753 	struct xfs_refcount_irec	rr_rrec;
1754 };
1755 
1756 /* Stuff an extent on the recovery list. */
1757 STATIC int
xfs_refcount_recover_extent(struct xfs_btree_cur * cur,const union xfs_btree_rec * rec,void * priv)1758 xfs_refcount_recover_extent(
1759 	struct xfs_btree_cur		*cur,
1760 	const union xfs_btree_rec	*rec,
1761 	void				*priv)
1762 {
1763 	struct list_head		*debris = priv;
1764 	struct xfs_refcount_recovery	*rr;
1765 
1766 	if (XFS_IS_CORRUPT(cur->bc_mp,
1767 			   be32_to_cpu(rec->refc.rc_refcount) != 1))
1768 		return -EFSCORRUPTED;
1769 
1770 	rr = kmalloc(sizeof(struct xfs_refcount_recovery),
1771 			GFP_KERNEL | __GFP_NOFAIL);
1772 	INIT_LIST_HEAD(&rr->rr_list);
1773 	xfs_refcount_btrec_to_irec(rec, &rr->rr_rrec);
1774 
1775 	if (XFS_IS_CORRUPT(cur->bc_mp,
1776 			   rr->rr_rrec.rc_domain != XFS_REFC_DOMAIN_COW)) {
1777 		kfree(rr);
1778 		return -EFSCORRUPTED;
1779 	}
1780 
1781 	list_add_tail(&rr->rr_list, debris);
1782 	return 0;
1783 }
1784 
1785 /* Find and remove leftover CoW reservations. */
1786 int
xfs_refcount_recover_cow_leftovers(struct xfs_mount * mp,struct xfs_perag * pag)1787 xfs_refcount_recover_cow_leftovers(
1788 	struct xfs_mount		*mp,
1789 	struct xfs_perag		*pag)
1790 {
1791 	struct xfs_trans		*tp;
1792 	struct xfs_btree_cur		*cur;
1793 	struct xfs_buf			*agbp;
1794 	struct xfs_refcount_recovery	*rr, *n;
1795 	struct list_head		debris;
1796 	union xfs_btree_irec		low;
1797 	union xfs_btree_irec		high;
1798 	xfs_fsblock_t			fsb;
1799 	int				error;
1800 
1801 	/* reflink filesystems mustn't have AGs larger than 2^31-1 blocks */
1802 	BUILD_BUG_ON(XFS_MAX_CRC_AG_BLOCKS >= XFS_REFC_COWFLAG);
1803 	if (mp->m_sb.sb_agblocks > XFS_MAX_CRC_AG_BLOCKS)
1804 		return -EOPNOTSUPP;
1805 
1806 	INIT_LIST_HEAD(&debris);
1807 
1808 	/*
1809 	 * In this first part, we use an empty transaction to gather up
1810 	 * all the leftover CoW extents so that we can subsequently
1811 	 * delete them.  The empty transaction is used to avoid
1812 	 * a buffer lock deadlock if there happens to be a loop in the
1813 	 * refcountbt because we're allowed to re-grab a buffer that is
1814 	 * already attached to our transaction.  When we're done
1815 	 * recording the CoW debris we cancel the (empty) transaction
1816 	 * and everything goes away cleanly.
1817 	 */
1818 	error = xfs_trans_alloc_empty(mp, &tp);
1819 	if (error)
1820 		return error;
1821 
1822 	error = xfs_alloc_read_agf(pag, tp, 0, &agbp);
1823 	if (error)
1824 		goto out_trans;
1825 	cur = xfs_refcountbt_init_cursor(mp, tp, agbp, pag);
1826 
1827 	/* Find all the leftover CoW staging extents. */
1828 	memset(&low, 0, sizeof(low));
1829 	memset(&high, 0, sizeof(high));
1830 	low.rc.rc_domain = high.rc.rc_domain = XFS_REFC_DOMAIN_COW;
1831 	high.rc.rc_startblock = -1U;
1832 	error = xfs_btree_query_range(cur, &low, &high,
1833 			xfs_refcount_recover_extent, &debris);
1834 	xfs_btree_del_cursor(cur, error);
1835 	xfs_trans_brelse(tp, agbp);
1836 	xfs_trans_cancel(tp);
1837 	if (error)
1838 		goto out_free;
1839 
1840 	/* Now iterate the list to free the leftovers */
1841 	list_for_each_entry_safe(rr, n, &debris, rr_list) {
1842 		/* Set up transaction. */
1843 		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
1844 		if (error)
1845 			goto out_free;
1846 
1847 		trace_xfs_refcount_recover_extent(mp, pag->pag_agno,
1848 				&rr->rr_rrec);
1849 
1850 		/* Free the orphan record */
1851 		fsb = XFS_AGB_TO_FSB(mp, pag->pag_agno,
1852 				rr->rr_rrec.rc_startblock);
1853 		xfs_refcount_free_cow_extent(tp, fsb,
1854 				rr->rr_rrec.rc_blockcount);
1855 
1856 		/* Free the block. */
1857 		xfs_free_extent_later(tp, fsb, rr->rr_rrec.rc_blockcount, NULL);
1858 
1859 		error = xfs_trans_commit(tp);
1860 		if (error)
1861 			goto out_free;
1862 
1863 		list_del(&rr->rr_list);
1864 		kfree(rr);
1865 	}
1866 
1867 	return error;
1868 out_trans:
1869 	xfs_trans_cancel(tp);
1870 out_free:
1871 	/* Free the leftover list */
1872 	list_for_each_entry_safe(rr, n, &debris, rr_list) {
1873 		list_del(&rr->rr_list);
1874 		kfree(rr);
1875 	}
1876 	return error;
1877 }
1878 
1879 /* Is there a record covering a given extent? */
1880 int
xfs_refcount_has_record(struct xfs_btree_cur * cur,enum xfs_refc_domain domain,xfs_agblock_t bno,xfs_extlen_t len,bool * exists)1881 xfs_refcount_has_record(
1882 	struct xfs_btree_cur	*cur,
1883 	enum xfs_refc_domain	domain,
1884 	xfs_agblock_t		bno,
1885 	xfs_extlen_t		len,
1886 	bool			*exists)
1887 {
1888 	union xfs_btree_irec	low;
1889 	union xfs_btree_irec	high;
1890 
1891 	memset(&low, 0, sizeof(low));
1892 	low.rc.rc_startblock = bno;
1893 	memset(&high, 0xFF, sizeof(high));
1894 	high.rc.rc_startblock = bno + len - 1;
1895 	low.rc.rc_domain = high.rc.rc_domain = domain;
1896 
1897 	return xfs_btree_has_record(cur, &low, &high, exists);
1898 }
1899 
1900 int __init
xfs_refcount_intent_init_cache(void)1901 xfs_refcount_intent_init_cache(void)
1902 {
1903 	xfs_refcount_intent_cache = kmem_cache_create("xfs_refc_intent",
1904 			sizeof(struct xfs_refcount_intent),
1905 			0, 0, NULL);
1906 
1907 	return xfs_refcount_intent_cache != NULL ? 0 : -ENOMEM;
1908 }
1909 
1910 void
xfs_refcount_intent_destroy_cache(void)1911 xfs_refcount_intent_destroy_cache(void)
1912 {
1913 	kmem_cache_destroy(xfs_refcount_intent_cache);
1914 	xfs_refcount_intent_cache = NULL;
1915 }
1916