1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
4 * Copyright (c) 2013 Red Hat, Inc.
5 * All Rights Reserved.
6 */
7#include "xfs.h"
8#include "xfs_fs.h"
9#include "xfs_shared.h"
10#include "xfs_format.h"
11#include "xfs_log_format.h"
12#include "xfs_trans_resv.h"
13#include "xfs_bit.h"
14#include "xfs_mount.h"
15#include "xfs_defer.h"
16#include "xfs_da_format.h"
17#include "xfs_da_btree.h"
18#include "xfs_inode.h"
19#include "xfs_trans.h"
20#include "xfs_bmap.h"
21#include "xfs_attr.h"
22#include "xfs_attr_remote.h"
23#include "xfs_trace.h"
24#include "xfs_error.h"
25#include "xfs_health.h"
26
27#define ATTR_RMTVALUE_MAPSIZE 1 /* # of map entries at once */
28
29/*
30 * Remote Attribute Values
31 * =======================
32 *
33 * Remote extended attribute values are conceptually simple -- they're written
34 * to data blocks mapped by an inode's attribute fork, and they have an upper
35 * size limit of 64k. Setting a value does not involve the XFS log.
36 *
37 * However, on a v5 filesystem, maximally sized remote attr values require one
38 * block more than 64k worth of space to hold both the remote attribute value
39 * header (64 bytes). On a 4k block filesystem this results in a 68k buffer;
40 * on a 64k block filesystem, this would be a 128k buffer. Note that the log
41 * format can only handle a dirty buffer of XFS_MAX_BLOCKSIZE length (64k).
42 * Therefore, we /must/ ensure that remote attribute value buffers never touch
43 * the logging system and therefore never have a log item.
44 */
45
46/* How many bytes can be stored in a remote value buffer? */
47inline unsigned int
48xfs_attr3_rmt_buf_space(
49 struct xfs_mount *mp)
50{
51 unsigned int blocksize = mp->m_attr_geo->blksize;
52
53 if (xfs_has_crc(mp))
54 return blocksize - sizeof(struct xfs_attr3_rmt_hdr);
55
56 return blocksize;
57}
58
59/* Compute number of fsblocks needed to store a remote attr value */
60unsigned int
61xfs_attr3_rmt_blocks(
62 struct xfs_mount *mp,
63 unsigned int attrlen)
64{
65 /*
66 * Each contiguous block has a header, so it is not just a simple
67 * attribute length to FSB conversion.
68 */
69 if (xfs_has_crc(mp))
70 return howmany(attrlen, xfs_attr3_rmt_buf_space(mp));
71
72 return XFS_B_TO_FSB(mp, attrlen);
73}
74
75/*
76 * Checking of the remote attribute header is split into two parts. The verifier
77 * does CRC, location and bounds checking, the unpacking function checks the
78 * attribute parameters and owner.
79 */
80static xfs_failaddr_t
81xfs_attr3_rmt_hdr_ok(
82 void *ptr,
83 xfs_ino_t ino,
84 uint32_t offset,
85 uint32_t size,
86 xfs_daddr_t bno)
87{
88 struct xfs_attr3_rmt_hdr *rmt = ptr;
89
90 if (bno != be64_to_cpu(rmt->rm_blkno))
91 return __this_address;
92 if (offset != be32_to_cpu(rmt->rm_offset))
93 return __this_address;
94 if (size != be32_to_cpu(rmt->rm_bytes))
95 return __this_address;
96 if (ino != be64_to_cpu(rmt->rm_owner))
97 return __this_address;
98
99 /* ok */
100 return NULL;
101}
102
103static xfs_failaddr_t
104xfs_attr3_rmt_verify(
105 struct xfs_mount *mp,
106 struct xfs_buf *bp,
107 void *ptr,
108 xfs_daddr_t bno)
109{
110 struct xfs_attr3_rmt_hdr *rmt = ptr;
111
112 if (!xfs_verify_magic(bp, rmt->rm_magic))
113 return __this_address;
114 if (!uuid_equal(&rmt->rm_uuid, &mp->m_sb.sb_meta_uuid))
115 return __this_address;
116 if (be64_to_cpu(rmt->rm_blkno) != bno)
117 return __this_address;
118 if (be32_to_cpu(rmt->rm_bytes) > mp->m_attr_geo->blksize - sizeof(*rmt))
119 return __this_address;
120 if (be32_to_cpu(rmt->rm_offset) +
121 be32_to_cpu(rmt->rm_bytes) > XFS_XATTR_SIZE_MAX)
122 return __this_address;
123 if (rmt->rm_owner == 0)
124 return __this_address;
125
126 return NULL;
127}
128
129static int
130__xfs_attr3_rmt_read_verify(
131 struct xfs_buf *bp,
132 bool check_crc,
133 xfs_failaddr_t *failaddr)
134{
135 struct xfs_mount *mp = bp->b_mount;
136 char *ptr;
137 unsigned int len;
138 xfs_daddr_t bno;
139 unsigned int blksize = mp->m_attr_geo->blksize;
140
141 /* no verification of non-crc buffers */
142 if (!xfs_has_crc(mp))
143 return 0;
144
145 ptr = bp->b_addr;
146 bno = xfs_buf_daddr(bp);
147 len = BBTOB(bp->b_length);
148 ASSERT(len >= blksize);
149
150 while (len > 0) {
151 if (check_crc &&
152 !xfs_verify_cksum(ptr, blksize, XFS_ATTR3_RMT_CRC_OFF)) {
153 *failaddr = __this_address;
154 return -EFSBADCRC;
155 }
156 *failaddr = xfs_attr3_rmt_verify(mp, bp, ptr, bno);
157 if (*failaddr)
158 return -EFSCORRUPTED;
159 len -= blksize;
160 ptr += blksize;
161 bno += BTOBB(blksize);
162 }
163
164 if (len != 0) {
165 *failaddr = __this_address;
166 return -EFSCORRUPTED;
167 }
168
169 return 0;
170}
171
172static void
173xfs_attr3_rmt_read_verify(
174 struct xfs_buf *bp)
175{
176 xfs_failaddr_t fa;
177 int error;
178
179 error = __xfs_attr3_rmt_read_verify(bp, true, &fa);
180 if (error)
181 xfs_verifier_error(bp, error, fa);
182}
183
184static xfs_failaddr_t
185xfs_attr3_rmt_verify_struct(
186 struct xfs_buf *bp)
187{
188 xfs_failaddr_t fa;
189 int error;
190
191 error = __xfs_attr3_rmt_read_verify(bp, false, &fa);
192 return error ? fa : NULL;
193}
194
195static void
196xfs_attr3_rmt_write_verify(
197 struct xfs_buf *bp)
198{
199 struct xfs_mount *mp = bp->b_mount;
200 xfs_failaddr_t fa;
201 unsigned int blksize = mp->m_attr_geo->blksize;
202 char *ptr;
203 int len;
204 xfs_daddr_t bno;
205
206 /* no verification of non-crc buffers */
207 if (!xfs_has_crc(mp))
208 return;
209
210 ptr = bp->b_addr;
211 bno = xfs_buf_daddr(bp);
212 len = BBTOB(bp->b_length);
213 ASSERT(len >= blksize);
214
215 while (len > 0) {
216 struct xfs_attr3_rmt_hdr *rmt = (struct xfs_attr3_rmt_hdr *)ptr;
217
218 fa = xfs_attr3_rmt_verify(mp, bp, ptr, bno);
219 if (fa) {
220 xfs_verifier_error(bp, -EFSCORRUPTED, fa);
221 return;
222 }
223
224 /*
225 * Ensure we aren't writing bogus LSNs to disk. See
226 * xfs_attr3_rmt_hdr_set() for the explanation.
227 */
228 if (rmt->rm_lsn != cpu_to_be64(NULLCOMMITLSN)) {
229 xfs_verifier_error(bp, -EFSCORRUPTED, __this_address);
230 return;
231 }
232 xfs_update_cksum(ptr, blksize, XFS_ATTR3_RMT_CRC_OFF);
233
234 len -= blksize;
235 ptr += blksize;
236 bno += BTOBB(blksize);
237 }
238
239 if (len != 0)
240 xfs_verifier_error(bp, -EFSCORRUPTED, __this_address);
241}
242
243const struct xfs_buf_ops xfs_attr3_rmt_buf_ops = {
244 .name = "xfs_attr3_rmt",
245 .magic = { 0, cpu_to_be32(XFS_ATTR3_RMT_MAGIC) },
246 .verify_read = xfs_attr3_rmt_read_verify,
247 .verify_write = xfs_attr3_rmt_write_verify,
248 .verify_struct = xfs_attr3_rmt_verify_struct,
249};
250
251STATIC int
252xfs_attr3_rmt_hdr_set(
253 struct xfs_mount *mp,
254 void *ptr,
255 xfs_ino_t ino,
256 uint32_t offset,
257 uint32_t size,
258 xfs_daddr_t bno)
259{
260 struct xfs_attr3_rmt_hdr *rmt = ptr;
261
262 if (!xfs_has_crc(mp))
263 return 0;
264
265 rmt->rm_magic = cpu_to_be32(XFS_ATTR3_RMT_MAGIC);
266 rmt->rm_offset = cpu_to_be32(offset);
267 rmt->rm_bytes = cpu_to_be32(size);
268 uuid_copy(&rmt->rm_uuid, &mp->m_sb.sb_meta_uuid);
269 rmt->rm_owner = cpu_to_be64(ino);
270 rmt->rm_blkno = cpu_to_be64(bno);
271
272 /*
273 * Remote attribute blocks are written synchronously, so we don't
274 * have an LSN that we can stamp in them that makes any sense to log
275 * recovery. To ensure that log recovery handles overwrites of these
276 * blocks sanely (i.e. once they've been freed and reallocated as some
277 * other type of metadata) we need to ensure that the LSN has a value
278 * that tells log recovery to ignore the LSN and overwrite the buffer
279 * with whatever is in it's log. To do this, we use the magic
280 * NULLCOMMITLSN to indicate that the LSN is invalid.
281 */
282 rmt->rm_lsn = cpu_to_be64(NULLCOMMITLSN);
283
284 return sizeof(struct xfs_attr3_rmt_hdr);
285}
286
287/*
288 * Helper functions to copy attribute data in and out of the one disk extents
289 */
290STATIC int
291xfs_attr_rmtval_copyout(
292 struct xfs_mount *mp,
293 struct xfs_buf *bp,
294 struct xfs_inode *dp,
295 xfs_ino_t owner,
296 unsigned int *offset,
297 unsigned int *valuelen,
298 uint8_t **dst)
299{
300 char *src = bp->b_addr;
301 xfs_daddr_t bno = xfs_buf_daddr(bp);
302 unsigned int len = BBTOB(bp->b_length);
303 unsigned int blksize = mp->m_attr_geo->blksize;
304
305 ASSERT(len >= blksize);
306
307 while (len > 0 && *valuelen > 0) {
308 unsigned int hdr_size = 0;
309 unsigned int byte_cnt = xfs_attr3_rmt_buf_space(mp);
310
311 byte_cnt = min(*valuelen, byte_cnt);
312
313 if (xfs_has_crc(mp)) {
314 if (xfs_attr3_rmt_hdr_ok(src, owner, *offset,
315 byte_cnt, bno)) {
316 xfs_alert(mp,
317"remote attribute header mismatch bno/off/len/owner (0x%llx/0x%x/Ox%x/0x%llx)",
318 bno, *offset, byte_cnt, owner);
319 xfs_dirattr_mark_sick(dp, XFS_ATTR_FORK);
320 return -EFSCORRUPTED;
321 }
322 hdr_size = sizeof(struct xfs_attr3_rmt_hdr);
323 }
324
325 memcpy(*dst, src + hdr_size, byte_cnt);
326
327 /* roll buffer forwards */
328 len -= blksize;
329 src += blksize;
330 bno += BTOBB(blksize);
331
332 /* roll attribute data forwards */
333 *valuelen -= byte_cnt;
334 *dst += byte_cnt;
335 *offset += byte_cnt;
336 }
337 return 0;
338}
339
340STATIC void
341xfs_attr_rmtval_copyin(
342 struct xfs_mount *mp,
343 struct xfs_buf *bp,
344 xfs_ino_t ino,
345 unsigned int *offset,
346 unsigned int *valuelen,
347 uint8_t **src)
348{
349 char *dst = bp->b_addr;
350 xfs_daddr_t bno = xfs_buf_daddr(bp);
351 unsigned int len = BBTOB(bp->b_length);
352 unsigned int blksize = mp->m_attr_geo->blksize;
353
354 ASSERT(len >= blksize);
355
356 while (len > 0 && *valuelen > 0) {
357 unsigned int hdr_size;
358 unsigned int byte_cnt = xfs_attr3_rmt_buf_space(mp);
359
360 byte_cnt = min(*valuelen, byte_cnt);
361 hdr_size = xfs_attr3_rmt_hdr_set(mp, dst, ino, *offset,
362 byte_cnt, bno);
363
364 memcpy(dst + hdr_size, *src, byte_cnt);
365
366 /*
367 * If this is the last block, zero the remainder of it.
368 * Check that we are actually the last block, too.
369 */
370 if (byte_cnt + hdr_size < blksize) {
371 ASSERT(*valuelen - byte_cnt == 0);
372 ASSERT(len == blksize);
373 memset(dst + hdr_size + byte_cnt, 0,
374 blksize - hdr_size - byte_cnt);
375 }
376
377 /* roll buffer forwards */
378 len -= blksize;
379 dst += blksize;
380 bno += BTOBB(blksize);
381
382 /* roll attribute data forwards */
383 *valuelen -= byte_cnt;
384 *src += byte_cnt;
385 *offset += byte_cnt;
386 }
387}
388
389/*
390 * Read the value associated with an attribute from the out-of-line buffer
391 * that we stored it in.
392 *
393 * Returns 0 on successful retrieval, otherwise an error.
394 */
395int
396xfs_attr_rmtval_get(
397 struct xfs_da_args *args)
398{
399 struct xfs_bmbt_irec map[ATTR_RMTVALUE_MAPSIZE];
400 struct xfs_mount *mp = args->dp->i_mount;
401 struct xfs_buf *bp;
402 xfs_dablk_t lblkno = args->rmtblkno;
403 uint8_t *dst = args->value;
404 unsigned int valuelen;
405 int nmap;
406 int error;
407 unsigned int blkcnt = args->rmtblkcnt;
408 int i;
409 unsigned int offset = 0;
410
411 trace_xfs_attr_rmtval_get(args);
412
413 ASSERT(args->valuelen != 0);
414 ASSERT(args->rmtvaluelen == args->valuelen);
415
416 valuelen = args->rmtvaluelen;
417 while (valuelen > 0) {
418 nmap = ATTR_RMTVALUE_MAPSIZE;
419 error = xfs_bmapi_read(args->dp, (xfs_fileoff_t)lblkno,
420 blkcnt, map, &nmap,
421 XFS_BMAPI_ATTRFORK);
422 if (error)
423 return error;
424 ASSERT(nmap >= 1);
425
426 for (i = 0; (i < nmap) && (valuelen > 0); i++) {
427 xfs_daddr_t dblkno;
428 int dblkcnt;
429
430 ASSERT((map[i].br_startblock != DELAYSTARTBLOCK) &&
431 (map[i].br_startblock != HOLESTARTBLOCK));
432 dblkno = XFS_FSB_TO_DADDR(mp, map[i].br_startblock);
433 dblkcnt = XFS_FSB_TO_BB(mp, map[i].br_blockcount);
434 error = xfs_buf_read(mp->m_ddev_targp, dblkno, dblkcnt,
435 0, &bp, &xfs_attr3_rmt_buf_ops);
436 if (xfs_metadata_is_sick(error))
437 xfs_dirattr_mark_sick(args->dp, XFS_ATTR_FORK);
438 /*
439 * ENODATA from disk implies a disk medium failure;
440 * ENODATA for xattrs means attribute not found, so
441 * disambiguate that here.
442 */
443 if (error == -ENODATA)
444 error = -EIO;
445 if (error)
446 return error;
447
448 error = xfs_attr_rmtval_copyout(mp, bp, args->dp,
449 args->owner, &offset, &valuelen, &dst);
450 xfs_buf_relse(bp);
451 if (error)
452 return error;
453
454 /* roll attribute extent map forwards */
455 lblkno += map[i].br_blockcount;
456 blkcnt -= map[i].br_blockcount;
457 }
458 }
459 ASSERT(valuelen == 0);
460 return 0;
461}
462
463/*
464 * Find a "hole" in the attribute address space large enough for us to drop the
465 * new attributes value into
466 */
467int
468xfs_attr_rmt_find_hole(
469 struct xfs_da_args *args)
470{
471 struct xfs_inode *dp = args->dp;
472 struct xfs_mount *mp = dp->i_mount;
473 int error;
474 unsigned int blkcnt;
475 xfs_fileoff_t lfileoff = 0;
476
477 /*
478 * Because CRC enable attributes have headers, we can't just do a
479 * straight byte to FSB conversion and have to take the header space
480 * into account.
481 */
482 blkcnt = xfs_attr3_rmt_blocks(mp, attrlen: args->rmtvaluelen);
483 error = xfs_bmap_first_unused(args->trans, args->dp, blkcnt, &lfileoff,
484 XFS_ATTR_FORK);
485 if (error)
486 return error;
487
488 args->rmtblkno = (xfs_dablk_t)lfileoff;
489 args->rmtblkcnt = blkcnt;
490
491 return 0;
492}
493
494int
495xfs_attr_rmtval_set_value(
496 struct xfs_da_args *args)
497{
498 struct xfs_inode *dp = args->dp;
499 struct xfs_mount *mp = dp->i_mount;
500 struct xfs_bmbt_irec map;
501 xfs_dablk_t lblkno;
502 uint8_t *src = args->value;
503 unsigned int blkcnt;
504 unsigned int valuelen;
505 int nmap;
506 int error;
507 unsigned int offset = 0;
508
509 /*
510 * Roll through the "value", copying the attribute value to the
511 * already-allocated blocks. Blocks are written synchronously
512 * so that we can know they are all on disk before we turn off
513 * the INCOMPLETE flag.
514 */
515 lblkno = args->rmtblkno;
516 blkcnt = args->rmtblkcnt;
517 valuelen = args->rmtvaluelen;
518 while (valuelen > 0) {
519 struct xfs_buf *bp;
520 xfs_daddr_t dblkno;
521 int dblkcnt;
522
523 ASSERT(blkcnt > 0);
524
525 nmap = 1;
526 error = xfs_bmapi_read(dp, (xfs_fileoff_t)lblkno,
527 blkcnt, &map, &nmap,
528 XFS_BMAPI_ATTRFORK);
529 if (error)
530 return error;
531 ASSERT(nmap == 1);
532 ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
533 (map.br_startblock != HOLESTARTBLOCK));
534
535 dblkno = XFS_FSB_TO_DADDR(mp, map.br_startblock),
536 dblkcnt = XFS_FSB_TO_BB(mp, map.br_blockcount);
537
538 error = xfs_buf_get(mp->m_ddev_targp, dblkno, dblkcnt, &bp);
539 if (error)
540 return error;
541 bp->b_ops = &xfs_attr3_rmt_buf_ops;
542
543 xfs_attr_rmtval_copyin(mp, bp, args->owner, &offset, &valuelen,
544 &src);
545
546 error = xfs_bwrite(bp); /* GROT: NOTE: synchronous write */
547 xfs_buf_relse(bp);
548 if (error)
549 return error;
550
551
552 /* roll attribute extent map forwards */
553 lblkno += map.br_blockcount;
554 blkcnt -= map.br_blockcount;
555 }
556 ASSERT(valuelen == 0);
557 return 0;
558}
559
560/* Mark stale any incore buffers for the remote value. */
561int
562xfs_attr_rmtval_stale(
563 struct xfs_inode *ip,
564 struct xfs_bmbt_irec *map,
565 xfs_buf_flags_t incore_flags)
566{
567 struct xfs_mount *mp = ip->i_mount;
568 struct xfs_buf *bp;
569 int error;
570
571 xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
572
573 if (XFS_IS_CORRUPT(mp, map->br_startblock == DELAYSTARTBLOCK) ||
574 XFS_IS_CORRUPT(mp, map->br_startblock == HOLESTARTBLOCK)) {
575 xfs_bmap_mark_sick(ip, XFS_ATTR_FORK);
576 return -EFSCORRUPTED;
577 }
578
579 error = xfs_buf_incore(mp->m_ddev_targp,
580 XFS_FSB_TO_DADDR(mp, map->br_startblock),
581 XFS_FSB_TO_BB(mp, map->br_blockcount),
582 incore_flags, &bp);
583 if (error) {
584 if (error == -ENOENT)
585 return 0;
586 return error;
587 }
588
589 xfs_buf_stale(bp);
590 xfs_buf_relse(bp);
591 return 0;
592}
593
594/*
595 * Find a hole for the attr and store it in the delayed attr context. This
596 * initializes the context to roll through allocating an attr extent for a
597 * delayed attr operation
598 */
599int
600xfs_attr_rmtval_find_space(
601 struct xfs_attr_intent *attr)
602{
603 struct xfs_da_args *args = attr->xattri_da_args;
604 struct xfs_bmbt_irec *map = &attr->xattri_map;
605 int error;
606
607 attr->xattri_lblkno = 0;
608 attr->xattri_blkcnt = 0;
609 args->rmtblkcnt = 0;
610 args->rmtblkno = 0;
611 memset(map, 0, sizeof(struct xfs_bmbt_irec));
612
613 error = xfs_attr_rmt_find_hole(args);
614 if (error)
615 return error;
616
617 attr->xattri_blkcnt = args->rmtblkcnt;
618 attr->xattri_lblkno = args->rmtblkno;
619
620 return 0;
621}
622
623/*
624 * Write one block of the value associated with an attribute into the
625 * out-of-line buffer that we have defined for it. This is similar to a subset
626 * of xfs_attr_rmtval_set, but records the current block to the delayed attr
627 * context, and leaves transaction handling to the caller.
628 */
629int
630xfs_attr_rmtval_set_blk(
631 struct xfs_attr_intent *attr)
632{
633 struct xfs_da_args *args = attr->xattri_da_args;
634 struct xfs_inode *dp = args->dp;
635 struct xfs_bmbt_irec *map = &attr->xattri_map;
636 int nmap;
637 int error;
638
639 nmap = 1;
640 error = xfs_bmapi_write(args->trans, dp,
641 (xfs_fileoff_t)attr->xattri_lblkno,
642 attr->xattri_blkcnt, XFS_BMAPI_ATTRFORK, args->total,
643 map, &nmap);
644 if (error)
645 return error;
646
647 ASSERT((map->br_startblock != DELAYSTARTBLOCK) &&
648 (map->br_startblock != HOLESTARTBLOCK));
649
650 /* roll attribute extent map forwards */
651 attr->xattri_lblkno += map->br_blockcount;
652 attr->xattri_blkcnt -= map->br_blockcount;
653
654 return 0;
655}
656
657/*
658 * Remove the value associated with an attribute by deleting the
659 * out-of-line buffer that it is stored on.
660 */
661int
662xfs_attr_rmtval_invalidate(
663 struct xfs_da_args *args)
664{
665 xfs_dablk_t lblkno;
666 unsigned int blkcnt;
667 int error;
668
669 /*
670 * Roll through the "value", invalidating the attribute value's blocks.
671 */
672 lblkno = args->rmtblkno;
673 blkcnt = args->rmtblkcnt;
674 while (blkcnt > 0) {
675 struct xfs_bmbt_irec map;
676 int nmap;
677
678 /*
679 * Try to remember where we decided to put the value.
680 */
681 nmap = 1;
682 error = xfs_bmapi_read(args->dp, (xfs_fileoff_t)lblkno,
683 blkcnt, &map, &nmap, XFS_BMAPI_ATTRFORK);
684 if (error)
685 return error;
686 if (XFS_IS_CORRUPT(args->dp->i_mount, nmap != 1)) {
687 xfs_bmap_mark_sick(args->dp, XFS_ATTR_FORK);
688 return -EFSCORRUPTED;
689 }
690 error = xfs_attr_rmtval_stale(args->dp, &map, XBF_TRYLOCK);
691 if (error)
692 return error;
693
694 lblkno += map.br_blockcount;
695 blkcnt -= map.br_blockcount;
696 }
697 return 0;
698}
699
700/*
701 * Remove the value associated with an attribute by deleting the out-of-line
702 * buffer that it is stored on. Returns -EAGAIN for the caller to refresh the
703 * transaction and re-call the function. Callers should keep calling this
704 * routine until it returns something other than -EAGAIN.
705 */
706int
707xfs_attr_rmtval_remove(
708 struct xfs_attr_intent *attr)
709{
710 struct xfs_da_args *args = attr->xattri_da_args;
711 int error, done;
712
713 /*
714 * Unmap value blocks for this attr.
715 */
716 error = xfs_bunmapi(args->trans, args->dp, args->rmtblkno,
717 args->rmtblkcnt, XFS_BMAPI_ATTRFORK, 1, &done);
718 if (error)
719 return error;
720
721 /*
722 * We don't need an explicit state here to pick up where we left off. We
723 * can figure it out using the !done return code. The actual value of
724 * attr->xattri_dela_state may be some value reminiscent of the calling
725 * function, but it's value is irrelevant with in the context of this
726 * function. Once we are done here, the next state is set as needed by
727 * the parent
728 */
729 if (!done) {
730 trace_xfs_attr_rmtval_remove_return(attr->xattri_dela_state,
731 args->dp);
732 return -EAGAIN;
733 }
734
735 args->rmtblkno = 0;
736 args->rmtblkcnt = 0;
737 return 0;
738}
739

source code of linux/fs/xfs/libxfs/xfs_attr_remote.c