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 /* Simple checks for refcount records. */
124 xfs_failaddr_t
xfs_refcount_check_irec(struct xfs_btree_cur * cur,const struct xfs_refcount_irec * irec)125 xfs_refcount_check_irec(
126 	struct xfs_btree_cur		*cur,
127 	const struct xfs_refcount_irec	*irec)
128 {
129 	struct xfs_perag		*pag = cur->bc_ag.pag;
130 
131 	if (irec->rc_blockcount == 0 || irec->rc_blockcount > MAXREFCEXTLEN)
132 		return __this_address;
133 
134 	if (!xfs_refcount_check_domain(irec))
135 		return __this_address;
136 
137 	/* check for valid extent range, including overflow */
138 	if (!xfs_verify_agbext(pag, irec->rc_startblock, irec->rc_blockcount))
139 		return __this_address;
140 
141 	if (irec->rc_refcount == 0 || irec->rc_refcount > MAXREFCOUNT)
142 		return __this_address;
143 
144 	return NULL;
145 }
146 
147 static inline int
xfs_refcount_complain_bad_rec(struct xfs_btree_cur * cur,xfs_failaddr_t fa,const struct xfs_refcount_irec * irec)148 xfs_refcount_complain_bad_rec(
149 	struct xfs_btree_cur		*cur,
150 	xfs_failaddr_t			fa,
151 	const struct xfs_refcount_irec	*irec)
152 {
153 	struct xfs_mount		*mp = cur->bc_mp;
154 
155 	xfs_warn(mp,
156  "Refcount BTree record corruption in AG %d detected at %pS!",
157 				cur->bc_ag.pag->pag_agno, fa);
158 	xfs_warn(mp,
159 		"Start block 0x%x, block count 0x%x, references 0x%x",
160 		irec->rc_startblock, irec->rc_blockcount, irec->rc_refcount);
161 	return -EFSCORRUPTED;
162 }
163 
164 /*
165  * Get the data from the pointed-to record.
166  */
167 int
xfs_refcount_get_rec(struct xfs_btree_cur * cur,struct xfs_refcount_irec * irec,int * stat)168 xfs_refcount_get_rec(
169 	struct xfs_btree_cur		*cur,
170 	struct xfs_refcount_irec	*irec,
171 	int				*stat)
172 {
173 	union xfs_btree_rec		*rec;
174 	xfs_failaddr_t			fa;
175 	int				error;
176 
177 	error = xfs_btree_get_rec(cur, &rec, stat);
178 	if (error || !*stat)
179 		return error;
180 
181 	xfs_refcount_btrec_to_irec(rec, irec);
182 	fa = xfs_refcount_check_irec(cur, irec);
183 	if (fa)
184 		return xfs_refcount_complain_bad_rec(cur, fa, irec);
185 
186 	trace_xfs_refcount_get(cur->bc_mp, cur->bc_ag.pag->pag_agno, irec);
187 	return 0;
188 }
189 
190 /*
191  * Update the record referred to by cur to the value given
192  * by [bno, len, refcount].
193  * This either works (return 0) or gets an EFSCORRUPTED error.
194  */
195 STATIC int
xfs_refcount_update(struct xfs_btree_cur * cur,struct xfs_refcount_irec * irec)196 xfs_refcount_update(
197 	struct xfs_btree_cur		*cur,
198 	struct xfs_refcount_irec	*irec)
199 {
200 	union xfs_btree_rec	rec;
201 	uint32_t		start;
202 	int			error;
203 
204 	trace_xfs_refcount_update(cur->bc_mp, cur->bc_ag.pag->pag_agno, irec);
205 
206 	start = xfs_refcount_encode_startblock(irec->rc_startblock,
207 			irec->rc_domain);
208 	rec.refc.rc_startblock = cpu_to_be32(start);
209 	rec.refc.rc_blockcount = cpu_to_be32(irec->rc_blockcount);
210 	rec.refc.rc_refcount = cpu_to_be32(irec->rc_refcount);
211 
212 	error = xfs_btree_update(cur, &rec);
213 	if (error)
214 		trace_xfs_refcount_update_error(cur->bc_mp,
215 				cur->bc_ag.pag->pag_agno, error, _RET_IP_);
216 	return error;
217 }
218 
219 /*
220  * Insert the record referred to by cur to the value given
221  * by [bno, len, refcount].
222  * This either works (return 0) or gets an EFSCORRUPTED error.
223  */
224 int
xfs_refcount_insert(struct xfs_btree_cur * cur,struct xfs_refcount_irec * irec,int * i)225 xfs_refcount_insert(
226 	struct xfs_btree_cur		*cur,
227 	struct xfs_refcount_irec	*irec,
228 	int				*i)
229 {
230 	int				error;
231 
232 	trace_xfs_refcount_insert(cur->bc_mp, cur->bc_ag.pag->pag_agno, irec);
233 
234 	cur->bc_rec.rc.rc_startblock = irec->rc_startblock;
235 	cur->bc_rec.rc.rc_blockcount = irec->rc_blockcount;
236 	cur->bc_rec.rc.rc_refcount = irec->rc_refcount;
237 	cur->bc_rec.rc.rc_domain = irec->rc_domain;
238 
239 	error = xfs_btree_insert(cur, i);
240 	if (error)
241 		goto out_error;
242 	if (XFS_IS_CORRUPT(cur->bc_mp, *i != 1)) {
243 		error = -EFSCORRUPTED;
244 		goto out_error;
245 	}
246 
247 out_error:
248 	if (error)
249 		trace_xfs_refcount_insert_error(cur->bc_mp,
250 				cur->bc_ag.pag->pag_agno, error, _RET_IP_);
251 	return error;
252 }
253 
254 /*
255  * Remove the record referred to by cur, then set the pointer to the spot
256  * where the record could be re-inserted, in case we want to increment or
257  * decrement the cursor.
258  * This either works (return 0) or gets an EFSCORRUPTED error.
259  */
260 STATIC int
xfs_refcount_delete(struct xfs_btree_cur * cur,int * i)261 xfs_refcount_delete(
262 	struct xfs_btree_cur	*cur,
263 	int			*i)
264 {
265 	struct xfs_refcount_irec	irec;
266 	int			found_rec;
267 	int			error;
268 
269 	error = xfs_refcount_get_rec(cur, &irec, &found_rec);
270 	if (error)
271 		goto out_error;
272 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
273 		error = -EFSCORRUPTED;
274 		goto out_error;
275 	}
276 	trace_xfs_refcount_delete(cur->bc_mp, cur->bc_ag.pag->pag_agno, &irec);
277 	error = xfs_btree_delete(cur, i);
278 	if (XFS_IS_CORRUPT(cur->bc_mp, *i != 1)) {
279 		error = -EFSCORRUPTED;
280 		goto out_error;
281 	}
282 	if (error)
283 		goto out_error;
284 	error = xfs_refcount_lookup_ge(cur, irec.rc_domain, irec.rc_startblock,
285 			&found_rec);
286 out_error:
287 	if (error)
288 		trace_xfs_refcount_delete_error(cur->bc_mp,
289 				cur->bc_ag.pag->pag_agno, error, _RET_IP_);
290 	return error;
291 }
292 
293 /*
294  * Adjusting the Reference Count
295  *
296  * As stated elsewhere, the reference count btree (refcbt) stores
297  * >1 reference counts for extents of physical blocks.  In this
298  * operation, we're either raising or lowering the reference count of
299  * some subrange stored in the tree:
300  *
301  *      <------ adjustment range ------>
302  * ----+   +---+-----+ +--+--------+---------
303  *  2  |   | 3 |  4  | |17|   55   |   10
304  * ----+   +---+-----+ +--+--------+---------
305  * X axis is physical blocks number;
306  * reference counts are the numbers inside the rectangles
307  *
308  * The first thing we need to do is to ensure that there are no
309  * refcount extents crossing either boundary of the range to be
310  * adjusted.  For any extent that does cross a boundary, split it into
311  * two extents so that we can increment the refcount of one of the
312  * pieces later:
313  *
314  *      <------ adjustment range ------>
315  * ----+   +---+-----+ +--+--------+----+----
316  *  2  |   | 3 |  2  | |17|   55   | 10 | 10
317  * ----+   +---+-----+ +--+--------+----+----
318  *
319  * For this next step, let's assume that all the physical blocks in
320  * the adjustment range are mapped to a file and are therefore in use
321  * at least once.  Therefore, we can infer that any gap in the
322  * refcount tree within the adjustment range represents a physical
323  * extent with refcount == 1:
324  *
325  *      <------ adjustment range ------>
326  * ----+---+---+-----+-+--+--------+----+----
327  *  2  |"1"| 3 |  2  |1|17|   55   | 10 | 10
328  * ----+---+---+-----+-+--+--------+----+----
329  *      ^
330  *
331  * For each extent that falls within the interval range, figure out
332  * which extent is to the left or the right of that extent.  Now we
333  * have a left, current, and right extent.  If the new reference count
334  * of the center extent enables us to merge left, center, and right
335  * into one record covering all three, do so.  If the center extent is
336  * at the left end of the range, abuts the left extent, and its new
337  * reference count matches the left extent's record, then merge them.
338  * If the center extent is at the right end of the range, abuts the
339  * right extent, and the reference counts match, merge those.  In the
340  * example, we can left merge (assuming an increment operation):
341  *
342  *      <------ adjustment range ------>
343  * --------+---+-----+-+--+--------+----+----
344  *    2    | 3 |  2  |1|17|   55   | 10 | 10
345  * --------+---+-----+-+--+--------+----+----
346  *          ^
347  *
348  * For all other extents within the range, adjust the reference count
349  * or delete it if the refcount falls below 2.  If we were
350  * incrementing, the end result looks like this:
351  *
352  *      <------ adjustment range ------>
353  * --------+---+-----+-+--+--------+----+----
354  *    2    | 4 |  3  |2|18|   56   | 11 | 10
355  * --------+---+-----+-+--+--------+----+----
356  *
357  * The result of a decrement operation looks as such:
358  *
359  *      <------ adjustment range ------>
360  * ----+   +---+       +--+--------+----+----
361  *  2  |   | 2 |       |16|   54   |  9 | 10
362  * ----+   +---+       +--+--------+----+----
363  *      DDDD    111111DD
364  *
365  * The blocks marked "D" are freed; the blocks marked "1" are only
366  * referenced once and therefore the record is removed from the
367  * refcount btree.
368  */
369 
370 /* Next block after this extent. */
371 static inline xfs_agblock_t
xfs_refc_next(struct xfs_refcount_irec * rc)372 xfs_refc_next(
373 	struct xfs_refcount_irec	*rc)
374 {
375 	return rc->rc_startblock + rc->rc_blockcount;
376 }
377 
378 /*
379  * Split a refcount extent that crosses agbno.
380  */
381 STATIC int
xfs_refcount_split_extent(struct xfs_btree_cur * cur,enum xfs_refc_domain domain,xfs_agblock_t agbno,bool * shape_changed)382 xfs_refcount_split_extent(
383 	struct xfs_btree_cur		*cur,
384 	enum xfs_refc_domain		domain,
385 	xfs_agblock_t			agbno,
386 	bool				*shape_changed)
387 {
388 	struct xfs_refcount_irec	rcext, tmp;
389 	int				found_rec;
390 	int				error;
391 
392 	*shape_changed = false;
393 	error = xfs_refcount_lookup_le(cur, domain, agbno, &found_rec);
394 	if (error)
395 		goto out_error;
396 	if (!found_rec)
397 		return 0;
398 
399 	error = xfs_refcount_get_rec(cur, &rcext, &found_rec);
400 	if (error)
401 		goto out_error;
402 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
403 		error = -EFSCORRUPTED;
404 		goto out_error;
405 	}
406 	if (rcext.rc_domain != domain)
407 		return 0;
408 	if (rcext.rc_startblock == agbno || xfs_refc_next(&rcext) <= agbno)
409 		return 0;
410 
411 	*shape_changed = true;
412 	trace_xfs_refcount_split_extent(cur->bc_mp, cur->bc_ag.pag->pag_agno,
413 			&rcext, agbno);
414 
415 	/* Establish the right extent. */
416 	tmp = rcext;
417 	tmp.rc_startblock = agbno;
418 	tmp.rc_blockcount -= (agbno - rcext.rc_startblock);
419 	error = xfs_refcount_update(cur, &tmp);
420 	if (error)
421 		goto out_error;
422 
423 	/* Insert the left extent. */
424 	tmp = rcext;
425 	tmp.rc_blockcount = agbno - rcext.rc_startblock;
426 	error = xfs_refcount_insert(cur, &tmp, &found_rec);
427 	if (error)
428 		goto out_error;
429 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
430 		error = -EFSCORRUPTED;
431 		goto out_error;
432 	}
433 	return error;
434 
435 out_error:
436 	trace_xfs_refcount_split_extent_error(cur->bc_mp,
437 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
438 	return error;
439 }
440 
441 /*
442  * Merge the left, center, and right extents.
443  */
444 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)445 xfs_refcount_merge_center_extents(
446 	struct xfs_btree_cur		*cur,
447 	struct xfs_refcount_irec	*left,
448 	struct xfs_refcount_irec	*center,
449 	struct xfs_refcount_irec	*right,
450 	unsigned long long		extlen,
451 	xfs_extlen_t			*aglen)
452 {
453 	int				error;
454 	int				found_rec;
455 
456 	trace_xfs_refcount_merge_center_extents(cur->bc_mp,
457 			cur->bc_ag.pag->pag_agno, left, center, right);
458 
459 	ASSERT(left->rc_domain == center->rc_domain);
460 	ASSERT(right->rc_domain == center->rc_domain);
461 
462 	/*
463 	 * Make sure the center and right extents are not in the btree.
464 	 * If the center extent was synthesized, the first delete call
465 	 * removes the right extent and we skip the second deletion.
466 	 * If center and right were in the btree, then the first delete
467 	 * call removes the center and the second one removes the right
468 	 * extent.
469 	 */
470 	error = xfs_refcount_lookup_ge(cur, center->rc_domain,
471 			center->rc_startblock, &found_rec);
472 	if (error)
473 		goto out_error;
474 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
475 		error = -EFSCORRUPTED;
476 		goto out_error;
477 	}
478 
479 	error = xfs_refcount_delete(cur, &found_rec);
480 	if (error)
481 		goto out_error;
482 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
483 		error = -EFSCORRUPTED;
484 		goto out_error;
485 	}
486 
487 	if (center->rc_refcount > 1) {
488 		error = xfs_refcount_delete(cur, &found_rec);
489 		if (error)
490 			goto out_error;
491 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
492 			error = -EFSCORRUPTED;
493 			goto out_error;
494 		}
495 	}
496 
497 	/* Enlarge the left extent. */
498 	error = xfs_refcount_lookup_le(cur, left->rc_domain,
499 			left->rc_startblock, &found_rec);
500 	if (error)
501 		goto out_error;
502 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
503 		error = -EFSCORRUPTED;
504 		goto out_error;
505 	}
506 
507 	left->rc_blockcount = extlen;
508 	error = xfs_refcount_update(cur, left);
509 	if (error)
510 		goto out_error;
511 
512 	*aglen = 0;
513 	return error;
514 
515 out_error:
516 	trace_xfs_refcount_merge_center_extents_error(cur->bc_mp,
517 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
518 	return error;
519 }
520 
521 /*
522  * Merge with the left extent.
523  */
524 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)525 xfs_refcount_merge_left_extent(
526 	struct xfs_btree_cur		*cur,
527 	struct xfs_refcount_irec	*left,
528 	struct xfs_refcount_irec	*cleft,
529 	xfs_agblock_t			*agbno,
530 	xfs_extlen_t			*aglen)
531 {
532 	int				error;
533 	int				found_rec;
534 
535 	trace_xfs_refcount_merge_left_extent(cur->bc_mp,
536 			cur->bc_ag.pag->pag_agno, left, cleft);
537 
538 	ASSERT(left->rc_domain == cleft->rc_domain);
539 
540 	/* If the extent at agbno (cleft) wasn't synthesized, remove it. */
541 	if (cleft->rc_refcount > 1) {
542 		error = xfs_refcount_lookup_le(cur, cleft->rc_domain,
543 				cleft->rc_startblock, &found_rec);
544 		if (error)
545 			goto out_error;
546 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
547 			error = -EFSCORRUPTED;
548 			goto out_error;
549 		}
550 
551 		error = xfs_refcount_delete(cur, &found_rec);
552 		if (error)
553 			goto out_error;
554 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
555 			error = -EFSCORRUPTED;
556 			goto out_error;
557 		}
558 	}
559 
560 	/* Enlarge the left extent. */
561 	error = xfs_refcount_lookup_le(cur, left->rc_domain,
562 			left->rc_startblock, &found_rec);
563 	if (error)
564 		goto out_error;
565 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
566 		error = -EFSCORRUPTED;
567 		goto out_error;
568 	}
569 
570 	left->rc_blockcount += cleft->rc_blockcount;
571 	error = xfs_refcount_update(cur, left);
572 	if (error)
573 		goto out_error;
574 
575 	*agbno += cleft->rc_blockcount;
576 	*aglen -= cleft->rc_blockcount;
577 	return error;
578 
579 out_error:
580 	trace_xfs_refcount_merge_left_extent_error(cur->bc_mp,
581 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
582 	return error;
583 }
584 
585 /*
586  * Merge with the right extent.
587  */
588 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)589 xfs_refcount_merge_right_extent(
590 	struct xfs_btree_cur		*cur,
591 	struct xfs_refcount_irec	*right,
592 	struct xfs_refcount_irec	*cright,
593 	xfs_extlen_t			*aglen)
594 {
595 	int				error;
596 	int				found_rec;
597 
598 	trace_xfs_refcount_merge_right_extent(cur->bc_mp,
599 			cur->bc_ag.pag->pag_agno, cright, right);
600 
601 	ASSERT(right->rc_domain == cright->rc_domain);
602 
603 	/*
604 	 * If the extent ending at agbno+aglen (cright) wasn't synthesized,
605 	 * remove it.
606 	 */
607 	if (cright->rc_refcount > 1) {
608 		error = xfs_refcount_lookup_le(cur, cright->rc_domain,
609 				cright->rc_startblock, &found_rec);
610 		if (error)
611 			goto out_error;
612 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
613 			error = -EFSCORRUPTED;
614 			goto out_error;
615 		}
616 
617 		error = xfs_refcount_delete(cur, &found_rec);
618 		if (error)
619 			goto out_error;
620 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
621 			error = -EFSCORRUPTED;
622 			goto out_error;
623 		}
624 	}
625 
626 	/* Enlarge the right extent. */
627 	error = xfs_refcount_lookup_le(cur, right->rc_domain,
628 			right->rc_startblock, &found_rec);
629 	if (error)
630 		goto out_error;
631 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
632 		error = -EFSCORRUPTED;
633 		goto out_error;
634 	}
635 
636 	right->rc_startblock -= cright->rc_blockcount;
637 	right->rc_blockcount += cright->rc_blockcount;
638 	error = xfs_refcount_update(cur, right);
639 	if (error)
640 		goto out_error;
641 
642 	*aglen -= cright->rc_blockcount;
643 	return error;
644 
645 out_error:
646 	trace_xfs_refcount_merge_right_extent_error(cur->bc_mp,
647 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
648 	return error;
649 }
650 
651 /*
652  * Find the left extent and the one after it (cleft).  This function assumes
653  * that we've already split any extent crossing agbno.
654  */
655 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)656 xfs_refcount_find_left_extents(
657 	struct xfs_btree_cur		*cur,
658 	struct xfs_refcount_irec	*left,
659 	struct xfs_refcount_irec	*cleft,
660 	enum xfs_refc_domain		domain,
661 	xfs_agblock_t			agbno,
662 	xfs_extlen_t			aglen)
663 {
664 	struct xfs_refcount_irec	tmp;
665 	int				error;
666 	int				found_rec;
667 
668 	left->rc_startblock = cleft->rc_startblock = NULLAGBLOCK;
669 	error = xfs_refcount_lookup_le(cur, domain, agbno - 1, &found_rec);
670 	if (error)
671 		goto out_error;
672 	if (!found_rec)
673 		return 0;
674 
675 	error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
676 	if (error)
677 		goto out_error;
678 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
679 		error = -EFSCORRUPTED;
680 		goto out_error;
681 	}
682 
683 	if (tmp.rc_domain != domain)
684 		return 0;
685 	if (xfs_refc_next(&tmp) != agbno)
686 		return 0;
687 	/* We have a left extent; retrieve (or invent) the next right one */
688 	*left = tmp;
689 
690 	error = xfs_btree_increment(cur, 0, &found_rec);
691 	if (error)
692 		goto out_error;
693 	if (found_rec) {
694 		error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
695 		if (error)
696 			goto out_error;
697 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
698 			error = -EFSCORRUPTED;
699 			goto out_error;
700 		}
701 
702 		if (tmp.rc_domain != domain)
703 			goto not_found;
704 
705 		/* if tmp starts at the end of our range, just use that */
706 		if (tmp.rc_startblock == agbno)
707 			*cleft = tmp;
708 		else {
709 			/*
710 			 * There's a gap in the refcntbt at the start of the
711 			 * range we're interested in (refcount == 1) so
712 			 * synthesize the implied extent and pass it back.
713 			 * We assume here that the agbno/aglen range was
714 			 * passed in from a data fork extent mapping and
715 			 * therefore is allocated to exactly one owner.
716 			 */
717 			cleft->rc_startblock = agbno;
718 			cleft->rc_blockcount = min(aglen,
719 					tmp.rc_startblock - agbno);
720 			cleft->rc_refcount = 1;
721 			cleft->rc_domain = domain;
722 		}
723 	} else {
724 not_found:
725 		/*
726 		 * No extents, so pretend that there's one covering the whole
727 		 * range.
728 		 */
729 		cleft->rc_startblock = agbno;
730 		cleft->rc_blockcount = aglen;
731 		cleft->rc_refcount = 1;
732 		cleft->rc_domain = domain;
733 	}
734 	trace_xfs_refcount_find_left_extent(cur->bc_mp, cur->bc_ag.pag->pag_agno,
735 			left, cleft, agbno);
736 	return error;
737 
738 out_error:
739 	trace_xfs_refcount_find_left_extent_error(cur->bc_mp,
740 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
741 	return error;
742 }
743 
744 /*
745  * Find the right extent and the one before it (cright).  This function
746  * assumes that we've already split any extents crossing agbno + aglen.
747  */
748 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)749 xfs_refcount_find_right_extents(
750 	struct xfs_btree_cur		*cur,
751 	struct xfs_refcount_irec	*right,
752 	struct xfs_refcount_irec	*cright,
753 	enum xfs_refc_domain		domain,
754 	xfs_agblock_t			agbno,
755 	xfs_extlen_t			aglen)
756 {
757 	struct xfs_refcount_irec	tmp;
758 	int				error;
759 	int				found_rec;
760 
761 	right->rc_startblock = cright->rc_startblock = NULLAGBLOCK;
762 	error = xfs_refcount_lookup_ge(cur, domain, agbno + aglen, &found_rec);
763 	if (error)
764 		goto out_error;
765 	if (!found_rec)
766 		return 0;
767 
768 	error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
769 	if (error)
770 		goto out_error;
771 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
772 		error = -EFSCORRUPTED;
773 		goto out_error;
774 	}
775 
776 	if (tmp.rc_domain != domain)
777 		return 0;
778 	if (tmp.rc_startblock != agbno + aglen)
779 		return 0;
780 	/* We have a right extent; retrieve (or invent) the next left one */
781 	*right = tmp;
782 
783 	error = xfs_btree_decrement(cur, 0, &found_rec);
784 	if (error)
785 		goto out_error;
786 	if (found_rec) {
787 		error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
788 		if (error)
789 			goto out_error;
790 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
791 			error = -EFSCORRUPTED;
792 			goto out_error;
793 		}
794 
795 		if (tmp.rc_domain != domain)
796 			goto not_found;
797 
798 		/* if tmp ends at the end of our range, just use that */
799 		if (xfs_refc_next(&tmp) == agbno + aglen)
800 			*cright = tmp;
801 		else {
802 			/*
803 			 * There's a gap in the refcntbt at the end of the
804 			 * range we're interested in (refcount == 1) so
805 			 * create the implied extent and pass it back.
806 			 * We assume here that the agbno/aglen range was
807 			 * passed in from a data fork extent mapping and
808 			 * therefore is allocated to exactly one owner.
809 			 */
810 			cright->rc_startblock = max(agbno, xfs_refc_next(&tmp));
811 			cright->rc_blockcount = right->rc_startblock -
812 					cright->rc_startblock;
813 			cright->rc_refcount = 1;
814 			cright->rc_domain = domain;
815 		}
816 	} else {
817 not_found:
818 		/*
819 		 * No extents, so pretend that there's one covering the whole
820 		 * range.
821 		 */
822 		cright->rc_startblock = agbno;
823 		cright->rc_blockcount = aglen;
824 		cright->rc_refcount = 1;
825 		cright->rc_domain = domain;
826 	}
827 	trace_xfs_refcount_find_right_extent(cur->bc_mp, cur->bc_ag.pag->pag_agno,
828 			cright, right, agbno + aglen);
829 	return error;
830 
831 out_error:
832 	trace_xfs_refcount_find_right_extent_error(cur->bc_mp,
833 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
834 	return error;
835 }
836 
837 /* Is this extent valid? */
838 static inline bool
xfs_refc_valid(const struct xfs_refcount_irec * rc)839 xfs_refc_valid(
840 	const struct xfs_refcount_irec	*rc)
841 {
842 	return rc->rc_startblock != NULLAGBLOCK;
843 }
844 
845 static inline xfs_nlink_t
xfs_refc_merge_refcount(const struct xfs_refcount_irec * irec,enum xfs_refc_adjust_op adjust)846 xfs_refc_merge_refcount(
847 	const struct xfs_refcount_irec	*irec,
848 	enum xfs_refc_adjust_op		adjust)
849 {
850 	/* Once a record hits MAXREFCOUNT, it is pinned there forever */
851 	if (irec->rc_refcount == MAXREFCOUNT)
852 		return MAXREFCOUNT;
853 	return irec->rc_refcount + adjust;
854 }
855 
856 static inline bool
xfs_refc_want_merge_center(const struct xfs_refcount_irec * left,const struct xfs_refcount_irec * cleft,const struct xfs_refcount_irec * cright,const struct xfs_refcount_irec * right,bool cleft_is_cright,enum xfs_refc_adjust_op adjust,unsigned long long * ulenp)857 xfs_refc_want_merge_center(
858 	const struct xfs_refcount_irec	*left,
859 	const struct xfs_refcount_irec	*cleft,
860 	const struct xfs_refcount_irec	*cright,
861 	const struct xfs_refcount_irec	*right,
862 	bool				cleft_is_cright,
863 	enum xfs_refc_adjust_op		adjust,
864 	unsigned long long		*ulenp)
865 {
866 	unsigned long long		ulen = left->rc_blockcount;
867 	xfs_nlink_t			new_refcount;
868 
869 	/*
870 	 * To merge with a center record, both shoulder records must be
871 	 * adjacent to the record we want to adjust.  This is only true if
872 	 * find_left and find_right made all four records valid.
873 	 */
874 	if (!xfs_refc_valid(left)  || !xfs_refc_valid(right) ||
875 	    !xfs_refc_valid(cleft) || !xfs_refc_valid(cright))
876 		return false;
877 
878 	/* There must only be one record for the entire range. */
879 	if (!cleft_is_cright)
880 		return false;
881 
882 	/* The shoulder record refcounts must match the new refcount. */
883 	new_refcount = xfs_refc_merge_refcount(cleft, adjust);
884 	if (left->rc_refcount != new_refcount)
885 		return false;
886 	if (right->rc_refcount != new_refcount)
887 		return false;
888 
889 	/*
890 	 * The new record cannot exceed the max length.  ulen is a ULL as the
891 	 * individual record block counts can be up to (u32 - 1) in length
892 	 * hence we need to catch u32 addition overflows here.
893 	 */
894 	ulen += cleft->rc_blockcount + right->rc_blockcount;
895 	if (ulen >= MAXREFCEXTLEN)
896 		return false;
897 
898 	*ulenp = ulen;
899 	return true;
900 }
901 
902 static inline bool
xfs_refc_want_merge_left(const struct xfs_refcount_irec * left,const struct xfs_refcount_irec * cleft,enum xfs_refc_adjust_op adjust)903 xfs_refc_want_merge_left(
904 	const struct xfs_refcount_irec	*left,
905 	const struct xfs_refcount_irec	*cleft,
906 	enum xfs_refc_adjust_op		adjust)
907 {
908 	unsigned long long		ulen = left->rc_blockcount;
909 	xfs_nlink_t			new_refcount;
910 
911 	/*
912 	 * For a left merge, the left shoulder record must be adjacent to the
913 	 * start of the range.  If this is true, find_left made left and cleft
914 	 * contain valid contents.
915 	 */
916 	if (!xfs_refc_valid(left) || !xfs_refc_valid(cleft))
917 		return false;
918 
919 	/* Left shoulder record refcount must match the new refcount. */
920 	new_refcount = xfs_refc_merge_refcount(cleft, adjust);
921 	if (left->rc_refcount != new_refcount)
922 		return false;
923 
924 	/*
925 	 * The new record cannot exceed the max length.  ulen is a ULL as the
926 	 * individual record block counts can be up to (u32 - 1) in length
927 	 * hence we need to catch u32 addition overflows here.
928 	 */
929 	ulen += cleft->rc_blockcount;
930 	if (ulen >= MAXREFCEXTLEN)
931 		return false;
932 
933 	return true;
934 }
935 
936 static inline bool
xfs_refc_want_merge_right(const struct xfs_refcount_irec * cright,const struct xfs_refcount_irec * right,enum xfs_refc_adjust_op adjust)937 xfs_refc_want_merge_right(
938 	const struct xfs_refcount_irec	*cright,
939 	const struct xfs_refcount_irec	*right,
940 	enum xfs_refc_adjust_op		adjust)
941 {
942 	unsigned long long		ulen = right->rc_blockcount;
943 	xfs_nlink_t			new_refcount;
944 
945 	/*
946 	 * For a right merge, the right shoulder record must be adjacent to the
947 	 * end of the range.  If this is true, find_right made cright and right
948 	 * contain valid contents.
949 	 */
950 	if (!xfs_refc_valid(right) || !xfs_refc_valid(cright))
951 		return false;
952 
953 	/* Right shoulder record refcount must match the new refcount. */
954 	new_refcount = xfs_refc_merge_refcount(cright, adjust);
955 	if (right->rc_refcount != new_refcount)
956 		return false;
957 
958 	/*
959 	 * The new record cannot exceed the max length.  ulen is a ULL as the
960 	 * individual record block counts can be up to (u32 - 1) in length
961 	 * hence we need to catch u32 addition overflows here.
962 	 */
963 	ulen += cright->rc_blockcount;
964 	if (ulen >= MAXREFCEXTLEN)
965 		return false;
966 
967 	return true;
968 }
969 
970 /*
971  * Try to merge with any extents on the boundaries of the adjustment range.
972  */
973 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)974 xfs_refcount_merge_extents(
975 	struct xfs_btree_cur	*cur,
976 	enum xfs_refc_domain	domain,
977 	xfs_agblock_t		*agbno,
978 	xfs_extlen_t		*aglen,
979 	enum xfs_refc_adjust_op adjust,
980 	bool			*shape_changed)
981 {
982 	struct xfs_refcount_irec	left = {0}, cleft = {0};
983 	struct xfs_refcount_irec	cright = {0}, right = {0};
984 	int				error;
985 	unsigned long long		ulen;
986 	bool				cequal;
987 
988 	*shape_changed = false;
989 	/*
990 	 * Find the extent just below agbno [left], just above agbno [cleft],
991 	 * just below (agbno + aglen) [cright], and just above (agbno + aglen)
992 	 * [right].
993 	 */
994 	error = xfs_refcount_find_left_extents(cur, &left, &cleft, domain,
995 			*agbno, *aglen);
996 	if (error)
997 		return error;
998 	error = xfs_refcount_find_right_extents(cur, &right, &cright, domain,
999 			*agbno, *aglen);
1000 	if (error)
1001 		return error;
1002 
1003 	/* No left or right extent to merge; exit. */
1004 	if (!xfs_refc_valid(&left) && !xfs_refc_valid(&right))
1005 		return 0;
1006 
1007 	cequal = (cleft.rc_startblock == cright.rc_startblock) &&
1008 		 (cleft.rc_blockcount == cright.rc_blockcount);
1009 
1010 	/* Try to merge left, cleft, and right.  cleft must == cright. */
1011 	if (xfs_refc_want_merge_center(&left, &cleft, &cright, &right, cequal,
1012 				adjust, &ulen)) {
1013 		*shape_changed = true;
1014 		return xfs_refcount_merge_center_extents(cur, &left, &cleft,
1015 				&right, ulen, aglen);
1016 	}
1017 
1018 	/* Try to merge left and cleft. */
1019 	if (xfs_refc_want_merge_left(&left, &cleft, adjust)) {
1020 		*shape_changed = true;
1021 		error = xfs_refcount_merge_left_extent(cur, &left, &cleft,
1022 				agbno, aglen);
1023 		if (error)
1024 			return error;
1025 
1026 		/*
1027 		 * If we just merged left + cleft and cleft == cright,
1028 		 * we no longer have a cright to merge with right.  We're done.
1029 		 */
1030 		if (cequal)
1031 			return 0;
1032 	}
1033 
1034 	/* Try to merge cright and right. */
1035 	if (xfs_refc_want_merge_right(&cright, &right, adjust)) {
1036 		*shape_changed = true;
1037 		return xfs_refcount_merge_right_extent(cur, &right, &cright,
1038 				aglen);
1039 	}
1040 
1041 	return 0;
1042 }
1043 
1044 /*
1045  * XXX: This is a pretty hand-wavy estimate.  The penalty for guessing
1046  * true incorrectly is a shutdown FS; the penalty for guessing false
1047  * incorrectly is more transaction rolls than might be necessary.
1048  * Be conservative here.
1049  */
1050 static bool
xfs_refcount_still_have_space(struct xfs_btree_cur * cur)1051 xfs_refcount_still_have_space(
1052 	struct xfs_btree_cur		*cur)
1053 {
1054 	unsigned long			overhead;
1055 
1056 	/*
1057 	 * Worst case estimate: full splits of the free space and rmap btrees
1058 	 * to handle each of the shape changes to the refcount btree.
1059 	 */
1060 	overhead = xfs_allocfree_block_count(cur->bc_mp,
1061 				cur->bc_ag.refc.shape_changes);
1062 	overhead += cur->bc_mp->m_refc_maxlevels;
1063 	overhead *= cur->bc_mp->m_sb.sb_blocksize;
1064 
1065 	/*
1066 	 * Only allow 2 refcount extent updates per transaction if the
1067 	 * refcount continue update "error" has been injected.
1068 	 */
1069 	if (cur->bc_ag.refc.nr_ops > 2 &&
1070 	    XFS_TEST_ERROR(false, cur->bc_mp,
1071 			XFS_ERRTAG_REFCOUNT_CONTINUE_UPDATE))
1072 		return false;
1073 
1074 	if (cur->bc_ag.refc.nr_ops == 0)
1075 		return true;
1076 	else if (overhead > cur->bc_tp->t_log_res)
1077 		return false;
1078 	return  cur->bc_tp->t_log_res - overhead >
1079 		cur->bc_ag.refc.nr_ops * XFS_REFCOUNT_ITEM_OVERHEAD;
1080 }
1081 
1082 /*
1083  * Adjust the refcounts of middle extents.  At this point we should have
1084  * split extents that crossed the adjustment range; merged with adjacent
1085  * extents; and updated agbno/aglen to reflect the merges.  Therefore,
1086  * all we have to do is update the extents inside [agbno, agbno + aglen].
1087  */
1088 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)1089 xfs_refcount_adjust_extents(
1090 	struct xfs_btree_cur	*cur,
1091 	xfs_agblock_t		*agbno,
1092 	xfs_extlen_t		*aglen,
1093 	enum xfs_refc_adjust_op	adj)
1094 {
1095 	struct xfs_refcount_irec	ext, tmp;
1096 	int				error;
1097 	int				found_rec, found_tmp;
1098 	xfs_fsblock_t			fsbno;
1099 
1100 	/* Merging did all the work already. */
1101 	if (*aglen == 0)
1102 		return 0;
1103 
1104 	error = xfs_refcount_lookup_ge(cur, XFS_REFC_DOMAIN_SHARED, *agbno,
1105 			&found_rec);
1106 	if (error)
1107 		goto out_error;
1108 
1109 	while (*aglen > 0 && xfs_refcount_still_have_space(cur)) {
1110 		error = xfs_refcount_get_rec(cur, &ext, &found_rec);
1111 		if (error)
1112 			goto out_error;
1113 		if (!found_rec || ext.rc_domain != XFS_REFC_DOMAIN_SHARED) {
1114 			ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
1115 			ext.rc_blockcount = 0;
1116 			ext.rc_refcount = 0;
1117 			ext.rc_domain = XFS_REFC_DOMAIN_SHARED;
1118 		}
1119 
1120 		/*
1121 		 * Deal with a hole in the refcount tree; if a file maps to
1122 		 * these blocks and there's no refcountbt record, pretend that
1123 		 * there is one with refcount == 1.
1124 		 */
1125 		if (ext.rc_startblock != *agbno) {
1126 			tmp.rc_startblock = *agbno;
1127 			tmp.rc_blockcount = min(*aglen,
1128 					ext.rc_startblock - *agbno);
1129 			tmp.rc_refcount = 1 + adj;
1130 			tmp.rc_domain = XFS_REFC_DOMAIN_SHARED;
1131 
1132 			trace_xfs_refcount_modify_extent(cur->bc_mp,
1133 					cur->bc_ag.pag->pag_agno, &tmp);
1134 
1135 			/*
1136 			 * Either cover the hole (increment) or
1137 			 * delete the range (decrement).
1138 			 */
1139 			cur->bc_ag.refc.nr_ops++;
1140 			if (tmp.rc_refcount) {
1141 				error = xfs_refcount_insert(cur, &tmp,
1142 						&found_tmp);
1143 				if (error)
1144 					goto out_error;
1145 				if (XFS_IS_CORRUPT(cur->bc_mp,
1146 						   found_tmp != 1)) {
1147 					error = -EFSCORRUPTED;
1148 					goto out_error;
1149 				}
1150 			} else {
1151 				fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
1152 						cur->bc_ag.pag->pag_agno,
1153 						tmp.rc_startblock);
1154 				error = xfs_free_extent_later(cur->bc_tp, fsbno,
1155 						  tmp.rc_blockcount, NULL,
1156 						  XFS_AG_RESV_NONE);
1157 				if (error)
1158 					goto out_error;
1159 			}
1160 
1161 			(*agbno) += tmp.rc_blockcount;
1162 			(*aglen) -= tmp.rc_blockcount;
1163 
1164 			/* Stop if there's nothing left to modify */
1165 			if (*aglen == 0 || !xfs_refcount_still_have_space(cur))
1166 				break;
1167 
1168 			/* Move the cursor to the start of ext. */
1169 			error = xfs_refcount_lookup_ge(cur,
1170 					XFS_REFC_DOMAIN_SHARED, *agbno,
1171 					&found_rec);
1172 			if (error)
1173 				goto out_error;
1174 		}
1175 
1176 		/*
1177 		 * A previous step trimmed agbno/aglen such that the end of the
1178 		 * range would not be in the middle of the record.  If this is
1179 		 * no longer the case, something is seriously wrong with the
1180 		 * btree.  Make sure we never feed the synthesized record into
1181 		 * the processing loop below.
1182 		 */
1183 		if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_blockcount == 0) ||
1184 		    XFS_IS_CORRUPT(cur->bc_mp, ext.rc_blockcount > *aglen)) {
1185 			error = -EFSCORRUPTED;
1186 			goto out_error;
1187 		}
1188 
1189 		/*
1190 		 * Adjust the reference count and either update the tree
1191 		 * (incr) or free the blocks (decr).
1192 		 */
1193 		if (ext.rc_refcount == MAXREFCOUNT)
1194 			goto skip;
1195 		ext.rc_refcount += adj;
1196 		trace_xfs_refcount_modify_extent(cur->bc_mp,
1197 				cur->bc_ag.pag->pag_agno, &ext);
1198 		cur->bc_ag.refc.nr_ops++;
1199 		if (ext.rc_refcount > 1) {
1200 			error = xfs_refcount_update(cur, &ext);
1201 			if (error)
1202 				goto out_error;
1203 		} else if (ext.rc_refcount == 1) {
1204 			error = xfs_refcount_delete(cur, &found_rec);
1205 			if (error)
1206 				goto out_error;
1207 			if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
1208 				error = -EFSCORRUPTED;
1209 				goto out_error;
1210 			}
1211 			goto advloop;
1212 		} else {
1213 			fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
1214 					cur->bc_ag.pag->pag_agno,
1215 					ext.rc_startblock);
1216 			error = xfs_free_extent_later(cur->bc_tp, fsbno,
1217 					ext.rc_blockcount, NULL,
1218 					XFS_AG_RESV_NONE);
1219 			if (error)
1220 				goto out_error;
1221 		}
1222 
1223 skip:
1224 		error = xfs_btree_increment(cur, 0, &found_rec);
1225 		if (error)
1226 			goto out_error;
1227 
1228 advloop:
1229 		(*agbno) += ext.rc_blockcount;
1230 		(*aglen) -= ext.rc_blockcount;
1231 	}
1232 
1233 	return error;
1234 out_error:
1235 	trace_xfs_refcount_modify_extent_error(cur->bc_mp,
1236 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
1237 	return error;
1238 }
1239 
1240 /* Adjust the reference count of a range of AG blocks. */
1241 STATIC int
xfs_refcount_adjust(struct xfs_btree_cur * cur,xfs_agblock_t * agbno,xfs_extlen_t * aglen,enum xfs_refc_adjust_op adj)1242 xfs_refcount_adjust(
1243 	struct xfs_btree_cur	*cur,
1244 	xfs_agblock_t		*agbno,
1245 	xfs_extlen_t		*aglen,
1246 	enum xfs_refc_adjust_op	adj)
1247 {
1248 	bool			shape_changed;
1249 	int			shape_changes = 0;
1250 	int			error;
1251 
1252 	if (adj == XFS_REFCOUNT_ADJUST_INCREASE)
1253 		trace_xfs_refcount_increase(cur->bc_mp,
1254 				cur->bc_ag.pag->pag_agno, *agbno, *aglen);
1255 	else
1256 		trace_xfs_refcount_decrease(cur->bc_mp,
1257 				cur->bc_ag.pag->pag_agno, *agbno, *aglen);
1258 
1259 	/*
1260 	 * Ensure that no rcextents cross the boundary of the adjustment range.
1261 	 */
1262 	error = xfs_refcount_split_extent(cur, XFS_REFC_DOMAIN_SHARED,
1263 			*agbno, &shape_changed);
1264 	if (error)
1265 		goto out_error;
1266 	if (shape_changed)
1267 		shape_changes++;
1268 
1269 	error = xfs_refcount_split_extent(cur, XFS_REFC_DOMAIN_SHARED,
1270 			*agbno + *aglen, &shape_changed);
1271 	if (error)
1272 		goto out_error;
1273 	if (shape_changed)
1274 		shape_changes++;
1275 
1276 	/*
1277 	 * Try to merge with the left or right extents of the range.
1278 	 */
1279 	error = xfs_refcount_merge_extents(cur, XFS_REFC_DOMAIN_SHARED,
1280 			agbno, aglen, adj, &shape_changed);
1281 	if (error)
1282 		goto out_error;
1283 	if (shape_changed)
1284 		shape_changes++;
1285 	if (shape_changes)
1286 		cur->bc_ag.refc.shape_changes++;
1287 
1288 	/* Now that we've taken care of the ends, adjust the middle extents */
1289 	error = xfs_refcount_adjust_extents(cur, agbno, aglen, adj);
1290 	if (error)
1291 		goto out_error;
1292 
1293 	return 0;
1294 
1295 out_error:
1296 	trace_xfs_refcount_adjust_error(cur->bc_mp, cur->bc_ag.pag->pag_agno,
1297 			error, _RET_IP_);
1298 	return error;
1299 }
1300 
1301 /* Clean up after calling xfs_refcount_finish_one. */
1302 void
xfs_refcount_finish_one_cleanup(struct xfs_trans * tp,struct xfs_btree_cur * rcur,int error)1303 xfs_refcount_finish_one_cleanup(
1304 	struct xfs_trans	*tp,
1305 	struct xfs_btree_cur	*rcur,
1306 	int			error)
1307 {
1308 	struct xfs_buf		*agbp;
1309 
1310 	if (rcur == NULL)
1311 		return;
1312 	agbp = rcur->bc_ag.agbp;
1313 	xfs_btree_del_cursor(rcur, error);
1314 	if (error)
1315 		xfs_trans_brelse(tp, agbp);
1316 }
1317 
1318 /*
1319  * Set up a continuation a deferred refcount operation by updating the intent.
1320  * Checks to make sure we're not going to run off the end of the AG.
1321  */
1322 static inline int
xfs_refcount_continue_op(struct xfs_btree_cur * cur,struct xfs_refcount_intent * ri,xfs_agblock_t new_agbno)1323 xfs_refcount_continue_op(
1324 	struct xfs_btree_cur		*cur,
1325 	struct xfs_refcount_intent	*ri,
1326 	xfs_agblock_t			new_agbno)
1327 {
1328 	struct xfs_mount		*mp = cur->bc_mp;
1329 	struct xfs_perag		*pag = cur->bc_ag.pag;
1330 
1331 	if (XFS_IS_CORRUPT(mp, !xfs_verify_agbext(pag, new_agbno,
1332 					ri->ri_blockcount)))
1333 		return -EFSCORRUPTED;
1334 
1335 	ri->ri_startblock = XFS_AGB_TO_FSB(mp, pag->pag_agno, new_agbno);
1336 
1337 	ASSERT(xfs_verify_fsbext(mp, ri->ri_startblock, ri->ri_blockcount));
1338 	ASSERT(pag->pag_agno == XFS_FSB_TO_AGNO(mp, ri->ri_startblock));
1339 
1340 	return 0;
1341 }
1342 
1343 /*
1344  * Process one of the deferred refcount operations.  We pass back the
1345  * btree cursor to maintain our lock on the btree between calls.
1346  * This saves time and eliminates a buffer deadlock between the
1347  * superblock and the AGF because we'll always grab them in the same
1348  * order.
1349  */
1350 int
xfs_refcount_finish_one(struct xfs_trans * tp,struct xfs_refcount_intent * ri,struct xfs_btree_cur ** pcur)1351 xfs_refcount_finish_one(
1352 	struct xfs_trans		*tp,
1353 	struct xfs_refcount_intent	*ri,
1354 	struct xfs_btree_cur		**pcur)
1355 {
1356 	struct xfs_mount		*mp = tp->t_mountp;
1357 	struct xfs_btree_cur		*rcur;
1358 	struct xfs_buf			*agbp = NULL;
1359 	int				error = 0;
1360 	xfs_agblock_t			bno;
1361 	unsigned long			nr_ops = 0;
1362 	int				shape_changes = 0;
1363 
1364 	bno = XFS_FSB_TO_AGBNO(mp, ri->ri_startblock);
1365 
1366 	trace_xfs_refcount_deferred(mp, XFS_FSB_TO_AGNO(mp, ri->ri_startblock),
1367 			ri->ri_type, XFS_FSB_TO_AGBNO(mp, ri->ri_startblock),
1368 			ri->ri_blockcount);
1369 
1370 	if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_REFCOUNT_FINISH_ONE))
1371 		return -EIO;
1372 
1373 	/*
1374 	 * If we haven't gotten a cursor or the cursor AG doesn't match
1375 	 * the startblock, get one now.
1376 	 */
1377 	rcur = *pcur;
1378 	if (rcur != NULL && rcur->bc_ag.pag != ri->ri_pag) {
1379 		nr_ops = rcur->bc_ag.refc.nr_ops;
1380 		shape_changes = rcur->bc_ag.refc.shape_changes;
1381 		xfs_refcount_finish_one_cleanup(tp, rcur, 0);
1382 		rcur = NULL;
1383 		*pcur = NULL;
1384 	}
1385 	if (rcur == NULL) {
1386 		error = xfs_alloc_read_agf(ri->ri_pag, tp,
1387 				XFS_ALLOC_FLAG_FREEING, &agbp);
1388 		if (error)
1389 			return error;
1390 
1391 		rcur = xfs_refcountbt_init_cursor(mp, tp, agbp, ri->ri_pag);
1392 		rcur->bc_ag.refc.nr_ops = nr_ops;
1393 		rcur->bc_ag.refc.shape_changes = shape_changes;
1394 	}
1395 	*pcur = rcur;
1396 
1397 	switch (ri->ri_type) {
1398 	case XFS_REFCOUNT_INCREASE:
1399 		error = xfs_refcount_adjust(rcur, &bno, &ri->ri_blockcount,
1400 				XFS_REFCOUNT_ADJUST_INCREASE);
1401 		if (error)
1402 			return error;
1403 		if (ri->ri_blockcount > 0)
1404 			error = xfs_refcount_continue_op(rcur, ri, bno);
1405 		break;
1406 	case XFS_REFCOUNT_DECREASE:
1407 		error = xfs_refcount_adjust(rcur, &bno, &ri->ri_blockcount,
1408 				XFS_REFCOUNT_ADJUST_DECREASE);
1409 		if (error)
1410 			return error;
1411 		if (ri->ri_blockcount > 0)
1412 			error = xfs_refcount_continue_op(rcur, ri, bno);
1413 		break;
1414 	case XFS_REFCOUNT_ALLOC_COW:
1415 		error = __xfs_refcount_cow_alloc(rcur, bno, ri->ri_blockcount);
1416 		if (error)
1417 			return error;
1418 		ri->ri_blockcount = 0;
1419 		break;
1420 	case XFS_REFCOUNT_FREE_COW:
1421 		error = __xfs_refcount_cow_free(rcur, bno, ri->ri_blockcount);
1422 		if (error)
1423 			return error;
1424 		ri->ri_blockcount = 0;
1425 		break;
1426 	default:
1427 		ASSERT(0);
1428 		return -EFSCORRUPTED;
1429 	}
1430 	if (!error && ri->ri_blockcount > 0)
1431 		trace_xfs_refcount_finish_one_leftover(mp, ri->ri_pag->pag_agno,
1432 				ri->ri_type, bno, ri->ri_blockcount);
1433 	return error;
1434 }
1435 
1436 /*
1437  * Record a refcount intent for later processing.
1438  */
1439 static void
__xfs_refcount_add(struct xfs_trans * tp,enum xfs_refcount_intent_type type,xfs_fsblock_t startblock,xfs_extlen_t blockcount)1440 __xfs_refcount_add(
1441 	struct xfs_trans		*tp,
1442 	enum xfs_refcount_intent_type	type,
1443 	xfs_fsblock_t			startblock,
1444 	xfs_extlen_t			blockcount)
1445 {
1446 	struct xfs_refcount_intent	*ri;
1447 
1448 	trace_xfs_refcount_defer(tp->t_mountp,
1449 			XFS_FSB_TO_AGNO(tp->t_mountp, startblock),
1450 			type, XFS_FSB_TO_AGBNO(tp->t_mountp, startblock),
1451 			blockcount);
1452 
1453 	ri = kmem_cache_alloc(xfs_refcount_intent_cache,
1454 			GFP_NOFS | __GFP_NOFAIL);
1455 	INIT_LIST_HEAD(&ri->ri_list);
1456 	ri->ri_type = type;
1457 	ri->ri_startblock = startblock;
1458 	ri->ri_blockcount = blockcount;
1459 
1460 	xfs_refcount_update_get_group(tp->t_mountp, ri);
1461 	xfs_defer_add(tp, XFS_DEFER_OPS_TYPE_REFCOUNT, &ri->ri_list);
1462 }
1463 
1464 /*
1465  * Increase the reference count of the blocks backing a file's extent.
1466  */
1467 void
xfs_refcount_increase_extent(struct xfs_trans * tp,struct xfs_bmbt_irec * PREV)1468 xfs_refcount_increase_extent(
1469 	struct xfs_trans		*tp,
1470 	struct xfs_bmbt_irec		*PREV)
1471 {
1472 	if (!xfs_has_reflink(tp->t_mountp))
1473 		return;
1474 
1475 	__xfs_refcount_add(tp, XFS_REFCOUNT_INCREASE, PREV->br_startblock,
1476 			PREV->br_blockcount);
1477 }
1478 
1479 /*
1480  * Decrease the reference count of the blocks backing a file's extent.
1481  */
1482 void
xfs_refcount_decrease_extent(struct xfs_trans * tp,struct xfs_bmbt_irec * PREV)1483 xfs_refcount_decrease_extent(
1484 	struct xfs_trans		*tp,
1485 	struct xfs_bmbt_irec		*PREV)
1486 {
1487 	if (!xfs_has_reflink(tp->t_mountp))
1488 		return;
1489 
1490 	__xfs_refcount_add(tp, XFS_REFCOUNT_DECREASE, PREV->br_startblock,
1491 			PREV->br_blockcount);
1492 }
1493 
1494 /*
1495  * Given an AG extent, find the lowest-numbered run of shared blocks
1496  * within that range and return the range in fbno/flen.  If
1497  * find_end_of_shared is set, return the longest contiguous extent of
1498  * shared blocks; if not, just return the first extent we find.  If no
1499  * shared blocks are found, fbno and flen will be set to NULLAGBLOCK
1500  * and 0, respectively.
1501  */
1502 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)1503 xfs_refcount_find_shared(
1504 	struct xfs_btree_cur		*cur,
1505 	xfs_agblock_t			agbno,
1506 	xfs_extlen_t			aglen,
1507 	xfs_agblock_t			*fbno,
1508 	xfs_extlen_t			*flen,
1509 	bool				find_end_of_shared)
1510 {
1511 	struct xfs_refcount_irec	tmp;
1512 	int				i;
1513 	int				have;
1514 	int				error;
1515 
1516 	trace_xfs_refcount_find_shared(cur->bc_mp, cur->bc_ag.pag->pag_agno,
1517 			agbno, aglen);
1518 
1519 	/* By default, skip the whole range */
1520 	*fbno = NULLAGBLOCK;
1521 	*flen = 0;
1522 
1523 	/* Try to find a refcount extent that crosses the start */
1524 	error = xfs_refcount_lookup_le(cur, XFS_REFC_DOMAIN_SHARED, agbno,
1525 			&have);
1526 	if (error)
1527 		goto out_error;
1528 	if (!have) {
1529 		/* No left extent, look at the next one */
1530 		error = xfs_btree_increment(cur, 0, &have);
1531 		if (error)
1532 			goto out_error;
1533 		if (!have)
1534 			goto done;
1535 	}
1536 	error = xfs_refcount_get_rec(cur, &tmp, &i);
1537 	if (error)
1538 		goto out_error;
1539 	if (XFS_IS_CORRUPT(cur->bc_mp, i != 1)) {
1540 		error = -EFSCORRUPTED;
1541 		goto out_error;
1542 	}
1543 	if (tmp.rc_domain != XFS_REFC_DOMAIN_SHARED)
1544 		goto done;
1545 
1546 	/* If the extent ends before the start, look at the next one */
1547 	if (tmp.rc_startblock + tmp.rc_blockcount <= agbno) {
1548 		error = xfs_btree_increment(cur, 0, &have);
1549 		if (error)
1550 			goto out_error;
1551 		if (!have)
1552 			goto done;
1553 		error = xfs_refcount_get_rec(cur, &tmp, &i);
1554 		if (error)
1555 			goto out_error;
1556 		if (XFS_IS_CORRUPT(cur->bc_mp, i != 1)) {
1557 			error = -EFSCORRUPTED;
1558 			goto out_error;
1559 		}
1560 		if (tmp.rc_domain != XFS_REFC_DOMAIN_SHARED)
1561 			goto done;
1562 	}
1563 
1564 	/* If the extent starts after the range we want, bail out */
1565 	if (tmp.rc_startblock >= agbno + aglen)
1566 		goto done;
1567 
1568 	/* We found the start of a shared extent! */
1569 	if (tmp.rc_startblock < agbno) {
1570 		tmp.rc_blockcount -= (agbno - tmp.rc_startblock);
1571 		tmp.rc_startblock = agbno;
1572 	}
1573 
1574 	*fbno = tmp.rc_startblock;
1575 	*flen = min(tmp.rc_blockcount, agbno + aglen - *fbno);
1576 	if (!find_end_of_shared)
1577 		goto done;
1578 
1579 	/* Otherwise, find the end of this shared extent */
1580 	while (*fbno + *flen < agbno + aglen) {
1581 		error = xfs_btree_increment(cur, 0, &have);
1582 		if (error)
1583 			goto out_error;
1584 		if (!have)
1585 			break;
1586 		error = xfs_refcount_get_rec(cur, &tmp, &i);
1587 		if (error)
1588 			goto out_error;
1589 		if (XFS_IS_CORRUPT(cur->bc_mp, i != 1)) {
1590 			error = -EFSCORRUPTED;
1591 			goto out_error;
1592 		}
1593 		if (tmp.rc_domain != XFS_REFC_DOMAIN_SHARED ||
1594 		    tmp.rc_startblock >= agbno + aglen ||
1595 		    tmp.rc_startblock != *fbno + *flen)
1596 			break;
1597 		*flen = min(*flen + tmp.rc_blockcount, agbno + aglen - *fbno);
1598 	}
1599 
1600 done:
1601 	trace_xfs_refcount_find_shared_result(cur->bc_mp,
1602 			cur->bc_ag.pag->pag_agno, *fbno, *flen);
1603 
1604 out_error:
1605 	if (error)
1606 		trace_xfs_refcount_find_shared_error(cur->bc_mp,
1607 				cur->bc_ag.pag->pag_agno, error, _RET_IP_);
1608 	return error;
1609 }
1610 
1611 /*
1612  * Recovering CoW Blocks After a Crash
1613  *
1614  * Due to the way that the copy on write mechanism works, there's a window of
1615  * opportunity in which we can lose track of allocated blocks during a crash.
1616  * Because CoW uses delayed allocation in the in-core CoW fork, writeback
1617  * causes blocks to be allocated and stored in the CoW fork.  The blocks are
1618  * no longer in the free space btree but are not otherwise recorded anywhere
1619  * until the write completes and the blocks are mapped into the file.  A crash
1620  * in between allocation and remapping results in the replacement blocks being
1621  * lost.  This situation is exacerbated by the CoW extent size hint because
1622  * allocations can hang around for long time.
1623  *
1624  * However, there is a place where we can record these allocations before they
1625  * become mappings -- the reference count btree.  The btree does not record
1626  * extents with refcount == 1, so we can record allocations with a refcount of
1627  * 1.  Blocks being used for CoW writeout cannot be shared, so there should be
1628  * no conflict with shared block records.  These mappings should be created
1629  * when we allocate blocks to the CoW fork and deleted when they're removed
1630  * from the CoW fork.
1631  *
1632  * Minor nit: records for in-progress CoW allocations and records for shared
1633  * extents must never be merged, to preserve the property that (except for CoW
1634  * allocations) there are no refcount btree entries with refcount == 1.  The
1635  * only time this could potentially happen is when unsharing a block that's
1636  * adjacent to CoW allocations, so we must be careful to avoid this.
1637  *
1638  * At mount time we recover lost CoW allocations by searching the refcount
1639  * btree for these refcount == 1 mappings.  These represent CoW allocations
1640  * that were in progress at the time the filesystem went down, so we can free
1641  * them to get the space back.
1642  *
1643  * This mechanism is superior to creating EFIs for unmapped CoW extents for
1644  * several reasons -- first, EFIs pin the tail of the log and would have to be
1645  * periodically relogged to avoid filling up the log.  Second, CoW completions
1646  * will have to file an EFD and create new EFIs for whatever remains in the
1647  * CoW fork; this partially takes care of (1) but extent-size reservations
1648  * will have to periodically relog even if there's no writeout in progress.
1649  * This can happen if the CoW extent size hint is set, which you really want.
1650  * Third, EFIs cannot currently be automatically relogged into newer
1651  * transactions to advance the log tail.  Fourth, stuffing the log full of
1652  * EFIs places an upper bound on the number of CoW allocations that can be
1653  * held filesystem-wide at any given time.  Recording them in the refcount
1654  * btree doesn't require us to maintain any state in memory and doesn't pin
1655  * the log.
1656  */
1657 /*
1658  * Adjust the refcounts of CoW allocations.  These allocations are "magic"
1659  * in that they're not referenced anywhere else in the filesystem, so we
1660  * stash them in the refcount btree with a refcount of 1 until either file
1661  * remapping (or CoW cancellation) happens.
1662  */
1663 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)1664 xfs_refcount_adjust_cow_extents(
1665 	struct xfs_btree_cur	*cur,
1666 	xfs_agblock_t		agbno,
1667 	xfs_extlen_t		aglen,
1668 	enum xfs_refc_adjust_op	adj)
1669 {
1670 	struct xfs_refcount_irec	ext, tmp;
1671 	int				error;
1672 	int				found_rec, found_tmp;
1673 
1674 	if (aglen == 0)
1675 		return 0;
1676 
1677 	/* Find any overlapping refcount records */
1678 	error = xfs_refcount_lookup_ge(cur, XFS_REFC_DOMAIN_COW, agbno,
1679 			&found_rec);
1680 	if (error)
1681 		goto out_error;
1682 	error = xfs_refcount_get_rec(cur, &ext, &found_rec);
1683 	if (error)
1684 		goto out_error;
1685 	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec &&
1686 				ext.rc_domain != XFS_REFC_DOMAIN_COW)) {
1687 		error = -EFSCORRUPTED;
1688 		goto out_error;
1689 	}
1690 	if (!found_rec) {
1691 		ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
1692 		ext.rc_blockcount = 0;
1693 		ext.rc_refcount = 0;
1694 		ext.rc_domain = XFS_REFC_DOMAIN_COW;
1695 	}
1696 
1697 	switch (adj) {
1698 	case XFS_REFCOUNT_ADJUST_COW_ALLOC:
1699 		/* Adding a CoW reservation, there should be nothing here. */
1700 		if (XFS_IS_CORRUPT(cur->bc_mp,
1701 				   agbno + aglen > ext.rc_startblock)) {
1702 			error = -EFSCORRUPTED;
1703 			goto out_error;
1704 		}
1705 
1706 		tmp.rc_startblock = agbno;
1707 		tmp.rc_blockcount = aglen;
1708 		tmp.rc_refcount = 1;
1709 		tmp.rc_domain = XFS_REFC_DOMAIN_COW;
1710 
1711 		trace_xfs_refcount_modify_extent(cur->bc_mp,
1712 				cur->bc_ag.pag->pag_agno, &tmp);
1713 
1714 		error = xfs_refcount_insert(cur, &tmp,
1715 				&found_tmp);
1716 		if (error)
1717 			goto out_error;
1718 		if (XFS_IS_CORRUPT(cur->bc_mp, found_tmp != 1)) {
1719 			error = -EFSCORRUPTED;
1720 			goto out_error;
1721 		}
1722 		break;
1723 	case XFS_REFCOUNT_ADJUST_COW_FREE:
1724 		/* Removing a CoW reservation, there should be one extent. */
1725 		if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_startblock != agbno)) {
1726 			error = -EFSCORRUPTED;
1727 			goto out_error;
1728 		}
1729 		if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_blockcount != aglen)) {
1730 			error = -EFSCORRUPTED;
1731 			goto out_error;
1732 		}
1733 		if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_refcount != 1)) {
1734 			error = -EFSCORRUPTED;
1735 			goto out_error;
1736 		}
1737 
1738 		ext.rc_refcount = 0;
1739 		trace_xfs_refcount_modify_extent(cur->bc_mp,
1740 				cur->bc_ag.pag->pag_agno, &ext);
1741 		error = xfs_refcount_delete(cur, &found_rec);
1742 		if (error)
1743 			goto out_error;
1744 		if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
1745 			error = -EFSCORRUPTED;
1746 			goto out_error;
1747 		}
1748 		break;
1749 	default:
1750 		ASSERT(0);
1751 	}
1752 
1753 	return error;
1754 out_error:
1755 	trace_xfs_refcount_modify_extent_error(cur->bc_mp,
1756 			cur->bc_ag.pag->pag_agno, error, _RET_IP_);
1757 	return error;
1758 }
1759 
1760 /*
1761  * Add or remove refcount btree entries for CoW reservations.
1762  */
1763 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)1764 xfs_refcount_adjust_cow(
1765 	struct xfs_btree_cur	*cur,
1766 	xfs_agblock_t		agbno,
1767 	xfs_extlen_t		aglen,
1768 	enum xfs_refc_adjust_op	adj)
1769 {
1770 	bool			shape_changed;
1771 	int			error;
1772 
1773 	/*
1774 	 * Ensure that no rcextents cross the boundary of the adjustment range.
1775 	 */
1776 	error = xfs_refcount_split_extent(cur, XFS_REFC_DOMAIN_COW,
1777 			agbno, &shape_changed);
1778 	if (error)
1779 		goto out_error;
1780 
1781 	error = xfs_refcount_split_extent(cur, XFS_REFC_DOMAIN_COW,
1782 			agbno + aglen, &shape_changed);
1783 	if (error)
1784 		goto out_error;
1785 
1786 	/*
1787 	 * Try to merge with the left or right extents of the range.
1788 	 */
1789 	error = xfs_refcount_merge_extents(cur, XFS_REFC_DOMAIN_COW, &agbno,
1790 			&aglen, adj, &shape_changed);
1791 	if (error)
1792 		goto out_error;
1793 
1794 	/* Now that we've taken care of the ends, adjust the middle extents */
1795 	error = xfs_refcount_adjust_cow_extents(cur, agbno, aglen, adj);
1796 	if (error)
1797 		goto out_error;
1798 
1799 	return 0;
1800 
1801 out_error:
1802 	trace_xfs_refcount_adjust_cow_error(cur->bc_mp, cur->bc_ag.pag->pag_agno,
1803 			error, _RET_IP_);
1804 	return error;
1805 }
1806 
1807 /*
1808  * Record a CoW allocation in the refcount btree.
1809  */
1810 STATIC int
__xfs_refcount_cow_alloc(struct xfs_btree_cur * rcur,xfs_agblock_t agbno,xfs_extlen_t aglen)1811 __xfs_refcount_cow_alloc(
1812 	struct xfs_btree_cur	*rcur,
1813 	xfs_agblock_t		agbno,
1814 	xfs_extlen_t		aglen)
1815 {
1816 	trace_xfs_refcount_cow_increase(rcur->bc_mp, rcur->bc_ag.pag->pag_agno,
1817 			agbno, aglen);
1818 
1819 	/* Add refcount btree reservation */
1820 	return xfs_refcount_adjust_cow(rcur, agbno, aglen,
1821 			XFS_REFCOUNT_ADJUST_COW_ALLOC);
1822 }
1823 
1824 /*
1825  * Remove a CoW allocation from the refcount btree.
1826  */
1827 STATIC int
__xfs_refcount_cow_free(struct xfs_btree_cur * rcur,xfs_agblock_t agbno,xfs_extlen_t aglen)1828 __xfs_refcount_cow_free(
1829 	struct xfs_btree_cur	*rcur,
1830 	xfs_agblock_t		agbno,
1831 	xfs_extlen_t		aglen)
1832 {
1833 	trace_xfs_refcount_cow_decrease(rcur->bc_mp, rcur->bc_ag.pag->pag_agno,
1834 			agbno, aglen);
1835 
1836 	/* Remove refcount btree reservation */
1837 	return xfs_refcount_adjust_cow(rcur, agbno, aglen,
1838 			XFS_REFCOUNT_ADJUST_COW_FREE);
1839 }
1840 
1841 /* Record a CoW staging extent in the refcount btree. */
1842 void
xfs_refcount_alloc_cow_extent(struct xfs_trans * tp,xfs_fsblock_t fsb,xfs_extlen_t len)1843 xfs_refcount_alloc_cow_extent(
1844 	struct xfs_trans		*tp,
1845 	xfs_fsblock_t			fsb,
1846 	xfs_extlen_t			len)
1847 {
1848 	struct xfs_mount		*mp = tp->t_mountp;
1849 
1850 	if (!xfs_has_reflink(mp))
1851 		return;
1852 
1853 	__xfs_refcount_add(tp, XFS_REFCOUNT_ALLOC_COW, fsb, len);
1854 
1855 	/* Add rmap entry */
1856 	xfs_rmap_alloc_extent(tp, XFS_FSB_TO_AGNO(mp, fsb),
1857 			XFS_FSB_TO_AGBNO(mp, fsb), len, XFS_RMAP_OWN_COW);
1858 }
1859 
1860 /* Forget a CoW staging event in the refcount btree. */
1861 void
xfs_refcount_free_cow_extent(struct xfs_trans * tp,xfs_fsblock_t fsb,xfs_extlen_t len)1862 xfs_refcount_free_cow_extent(
1863 	struct xfs_trans		*tp,
1864 	xfs_fsblock_t			fsb,
1865 	xfs_extlen_t			len)
1866 {
1867 	struct xfs_mount		*mp = tp->t_mountp;
1868 
1869 	if (!xfs_has_reflink(mp))
1870 		return;
1871 
1872 	/* Remove rmap entry */
1873 	xfs_rmap_free_extent(tp, XFS_FSB_TO_AGNO(mp, fsb),
1874 			XFS_FSB_TO_AGBNO(mp, fsb), len, XFS_RMAP_OWN_COW);
1875 	__xfs_refcount_add(tp, XFS_REFCOUNT_FREE_COW, fsb, len);
1876 }
1877 
1878 struct xfs_refcount_recovery {
1879 	struct list_head		rr_list;
1880 	struct xfs_refcount_irec	rr_rrec;
1881 };
1882 
1883 /* Stuff an extent on the recovery list. */
1884 STATIC int
xfs_refcount_recover_extent(struct xfs_btree_cur * cur,const union xfs_btree_rec * rec,void * priv)1885 xfs_refcount_recover_extent(
1886 	struct xfs_btree_cur		*cur,
1887 	const union xfs_btree_rec	*rec,
1888 	void				*priv)
1889 {
1890 	struct list_head		*debris = priv;
1891 	struct xfs_refcount_recovery	*rr;
1892 
1893 	if (XFS_IS_CORRUPT(cur->bc_mp,
1894 			   be32_to_cpu(rec->refc.rc_refcount) != 1))
1895 		return -EFSCORRUPTED;
1896 
1897 	rr = kmalloc(sizeof(struct xfs_refcount_recovery),
1898 			GFP_KERNEL | __GFP_NOFAIL);
1899 	INIT_LIST_HEAD(&rr->rr_list);
1900 	xfs_refcount_btrec_to_irec(rec, &rr->rr_rrec);
1901 
1902 	if (xfs_refcount_check_irec(cur, &rr->rr_rrec) != NULL ||
1903 	    XFS_IS_CORRUPT(cur->bc_mp,
1904 			   rr->rr_rrec.rc_domain != XFS_REFC_DOMAIN_COW)) {
1905 		kfree(rr);
1906 		return -EFSCORRUPTED;
1907 	}
1908 
1909 	list_add_tail(&rr->rr_list, debris);
1910 	return 0;
1911 }
1912 
1913 /* Find and remove leftover CoW reservations. */
1914 int
xfs_refcount_recover_cow_leftovers(struct xfs_mount * mp,struct xfs_perag * pag)1915 xfs_refcount_recover_cow_leftovers(
1916 	struct xfs_mount		*mp,
1917 	struct xfs_perag		*pag)
1918 {
1919 	struct xfs_trans		*tp;
1920 	struct xfs_btree_cur		*cur;
1921 	struct xfs_buf			*agbp;
1922 	struct xfs_refcount_recovery	*rr, *n;
1923 	struct list_head		debris;
1924 	union xfs_btree_irec		low = {
1925 		.rc.rc_domain		= XFS_REFC_DOMAIN_COW,
1926 	};
1927 	union xfs_btree_irec		high = {
1928 		.rc.rc_domain		= XFS_REFC_DOMAIN_COW,
1929 		.rc.rc_startblock	= -1U,
1930 	};
1931 	xfs_fsblock_t			fsb;
1932 	int				error;
1933 
1934 	/* reflink filesystems mustn't have AGs larger than 2^31-1 blocks */
1935 	BUILD_BUG_ON(XFS_MAX_CRC_AG_BLOCKS >= XFS_REFC_COWFLAG);
1936 	if (mp->m_sb.sb_agblocks > XFS_MAX_CRC_AG_BLOCKS)
1937 		return -EOPNOTSUPP;
1938 
1939 	INIT_LIST_HEAD(&debris);
1940 
1941 	/*
1942 	 * In this first part, we use an empty transaction to gather up
1943 	 * all the leftover CoW extents so that we can subsequently
1944 	 * delete them.  The empty transaction is used to avoid
1945 	 * a buffer lock deadlock if there happens to be a loop in the
1946 	 * refcountbt because we're allowed to re-grab a buffer that is
1947 	 * already attached to our transaction.  When we're done
1948 	 * recording the CoW debris we cancel the (empty) transaction
1949 	 * and everything goes away cleanly.
1950 	 */
1951 	error = xfs_trans_alloc_empty(mp, &tp);
1952 	if (error)
1953 		return error;
1954 
1955 	error = xfs_alloc_read_agf(pag, tp, 0, &agbp);
1956 	if (error)
1957 		goto out_trans;
1958 	cur = xfs_refcountbt_init_cursor(mp, tp, agbp, pag);
1959 
1960 	/* Find all the leftover CoW staging extents. */
1961 	error = xfs_btree_query_range(cur, &low, &high,
1962 			xfs_refcount_recover_extent, &debris);
1963 	xfs_btree_del_cursor(cur, error);
1964 	xfs_trans_brelse(tp, agbp);
1965 	xfs_trans_cancel(tp);
1966 	if (error)
1967 		goto out_free;
1968 
1969 	/* Now iterate the list to free the leftovers */
1970 	list_for_each_entry_safe(rr, n, &debris, rr_list) {
1971 		/* Set up transaction. */
1972 		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
1973 		if (error)
1974 			goto out_free;
1975 
1976 		trace_xfs_refcount_recover_extent(mp, pag->pag_agno,
1977 				&rr->rr_rrec);
1978 
1979 		/* Free the orphan record */
1980 		fsb = XFS_AGB_TO_FSB(mp, pag->pag_agno,
1981 				rr->rr_rrec.rc_startblock);
1982 		xfs_refcount_free_cow_extent(tp, fsb,
1983 				rr->rr_rrec.rc_blockcount);
1984 
1985 		/* Free the block. */
1986 		error = xfs_free_extent_later(tp, fsb,
1987 				rr->rr_rrec.rc_blockcount, NULL,
1988 				XFS_AG_RESV_NONE);
1989 		if (error)
1990 			goto out_trans;
1991 
1992 		error = xfs_trans_commit(tp);
1993 		if (error)
1994 			goto out_free;
1995 
1996 		list_del(&rr->rr_list);
1997 		kfree(rr);
1998 	}
1999 
2000 	return error;
2001 out_trans:
2002 	xfs_trans_cancel(tp);
2003 out_free:
2004 	/* Free the leftover list */
2005 	list_for_each_entry_safe(rr, n, &debris, rr_list) {
2006 		list_del(&rr->rr_list);
2007 		kfree(rr);
2008 	}
2009 	return error;
2010 }
2011 
2012 /*
2013  * Scan part of the keyspace of the refcount records and tell us if the area
2014  * has no records, is fully mapped by records, or is partially filled.
2015  */
2016 int
xfs_refcount_has_records(struct xfs_btree_cur * cur,enum xfs_refc_domain domain,xfs_agblock_t bno,xfs_extlen_t len,enum xbtree_recpacking * outcome)2017 xfs_refcount_has_records(
2018 	struct xfs_btree_cur	*cur,
2019 	enum xfs_refc_domain	domain,
2020 	xfs_agblock_t		bno,
2021 	xfs_extlen_t		len,
2022 	enum xbtree_recpacking	*outcome)
2023 {
2024 	union xfs_btree_irec	low;
2025 	union xfs_btree_irec	high;
2026 
2027 	memset(&low, 0, sizeof(low));
2028 	low.rc.rc_startblock = bno;
2029 	memset(&high, 0xFF, sizeof(high));
2030 	high.rc.rc_startblock = bno + len - 1;
2031 	low.rc.rc_domain = high.rc.rc_domain = domain;
2032 
2033 	return xfs_btree_has_records(cur, &low, &high, NULL, outcome);
2034 }
2035 
2036 int __init
xfs_refcount_intent_init_cache(void)2037 xfs_refcount_intent_init_cache(void)
2038 {
2039 	xfs_refcount_intent_cache = kmem_cache_create("xfs_refc_intent",
2040 			sizeof(struct xfs_refcount_intent),
2041 			0, 0, NULL);
2042 
2043 	return xfs_refcount_intent_cache != NULL ? 0 : -ENOMEM;
2044 }
2045 
2046 void
xfs_refcount_intent_destroy_cache(void)2047 xfs_refcount_intent_destroy_cache(void)
2048 {
2049 	kmem_cache_destroy(xfs_refcount_intent_cache);
2050 	xfs_refcount_intent_cache = NULL;
2051 }
2052