1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
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_inode.h"
15 #include "xfs_errortag.h"
16 #include "xfs_error.h"
17 #include "xfs_cksum.h"
18 #include "xfs_icache.h"
19 #include "xfs_trans.h"
20 #include "xfs_ialloc.h"
23 #include <linux/iversion.h>
26 * Check that none of the inode's in the buffer have a next
27 * unlinked field of 0.
39 j = mp->m_inode_cluster_size >> mp->m_sb.sb_inodelog;
41 for (i = 0; i < j; i++) {
42 dip = xfs_buf_offset(bp, i * mp->m_sb.sb_inodesize);
43 if (!dip->di_next_unlinked) {
45 "Detected bogus zero next_unlinked field in inode %d buffer 0x%llx.",
46 i, (long long)bp->b_bn);
53 xfs_dinode_good_version(
57 if (xfs_sb_version_hascrc(&mp->m_sb))
60 return version == 1 || version == 2;
64 * If we are doing readahead on an inode buffer, we might be in log recovery
65 * reading an inode allocation buffer that hasn't yet been replayed, and hence
66 * has not had the inode cores stamped into it. Hence for readahead, the buffer
67 * may be potentially invalid.
69 * If the readahead buffer is invalid, we need to mark it with an error and
70 * clear the DONE status of the buffer so that a followup read will re-read it
71 * from disk. We don't report the error otherwise to avoid warnings during log
72 * recovery and we don't get unnecssary panics on debug kernels. We use EIO here
73 * because all we want to do is say readahead failed; there is no-one to report
74 * the error to, so this will distinguish it from a non-ra verifier failure.
75 * Changes to this readahead error behavour also need to be reflected in
76 * xfs_dquot_buf_readahead_verify().
83 struct xfs_mount *mp = bp->b_target->bt_mount;
89 * Validate the magic number and version of every inode in the buffer
91 agno = xfs_daddr_to_agno(mp, XFS_BUF_ADDR(bp));
92 ni = XFS_BB_TO_FSB(mp, bp->b_length) * mp->m_sb.sb_inopblock;
93 for (i = 0; i < ni; i++) {
96 xfs_agino_t unlinked_ino;
98 dip = xfs_buf_offset(bp, (i << mp->m_sb.sb_inodelog));
99 unlinked_ino = be32_to_cpu(dip->di_next_unlinked);
100 di_ok = dip->di_magic == cpu_to_be16(XFS_DINODE_MAGIC) &&
101 xfs_dinode_good_version(mp, dip->di_version) &&
102 (unlinked_ino == NULLAGINO ||
103 xfs_verify_agino(mp, agno, unlinked_ino));
104 if (unlikely(XFS_TEST_ERROR(!di_ok, mp,
105 XFS_ERRTAG_ITOBP_INOTOBP))) {
107 bp->b_flags &= ~XBF_DONE;
108 xfs_buf_ioerror(bp, -EIO);
114 "bad inode magic/vsn daddr %lld #%d (magic=%x)",
115 (unsigned long long)bp->b_bn, i,
116 be16_to_cpu(dip->di_magic));
118 xfs_buf_verifier_error(bp, -EFSCORRUPTED,
119 __func__, dip, sizeof(*dip),
128 xfs_inode_buf_read_verify(
131 xfs_inode_buf_verify(bp, false);
135 xfs_inode_buf_readahead_verify(
138 xfs_inode_buf_verify(bp, true);
142 xfs_inode_buf_write_verify(
145 xfs_inode_buf_verify(bp, false);
148 const struct xfs_buf_ops xfs_inode_buf_ops = {
150 .verify_read = xfs_inode_buf_read_verify,
151 .verify_write = xfs_inode_buf_write_verify,
154 const struct xfs_buf_ops xfs_inode_buf_ra_ops = {
155 .name = "xxfs_inode_ra",
156 .verify_read = xfs_inode_buf_readahead_verify,
157 .verify_write = xfs_inode_buf_write_verify,
162 * This routine is called to map an inode to the buffer containing the on-disk
163 * version of the inode. It returns a pointer to the buffer containing the
164 * on-disk inode in the bpp parameter, and in the dipp parameter it returns a
165 * pointer to the on-disk inode within that buffer.
167 * If a non-zero error is returned, then the contents of bpp and dipp are
172 struct xfs_mount *mp,
173 struct xfs_trans *tp,
174 struct xfs_imap *imap,
175 struct xfs_dinode **dipp,
176 struct xfs_buf **bpp,
183 buf_flags |= XBF_UNMAPPED;
184 error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, imap->im_blkno,
185 (int)imap->im_len, buf_flags, &bp,
188 if (error == -EAGAIN) {
189 ASSERT(buf_flags & XBF_TRYLOCK);
192 xfs_warn(mp, "%s: xfs_trans_read_buf() returned error %d.",
198 *dipp = xfs_buf_offset(bp, imap->im_boffset);
204 struct xfs_inode *ip,
205 struct xfs_dinode *from)
207 struct xfs_icdinode *to = &ip->i_d;
208 struct inode *inode = VFS_I(ip);
212 * Convert v1 inodes immediately to v2 inode format as this is the
213 * minimum inode version format we support in the rest of the code.
215 to->di_version = from->di_version;
216 if (to->di_version == 1) {
217 set_nlink(inode, be16_to_cpu(from->di_onlink));
218 to->di_projid_lo = 0;
219 to->di_projid_hi = 0;
222 set_nlink(inode, be32_to_cpu(from->di_nlink));
223 to->di_projid_lo = be16_to_cpu(from->di_projid_lo);
224 to->di_projid_hi = be16_to_cpu(from->di_projid_hi);
227 to->di_format = from->di_format;
228 to->di_uid = be32_to_cpu(from->di_uid);
229 to->di_gid = be32_to_cpu(from->di_gid);
230 to->di_flushiter = be16_to_cpu(from->di_flushiter);
233 * Time is signed, so need to convert to signed 32 bit before
234 * storing in inode timestamp which may be 64 bit. Otherwise
235 * a time before epoch is converted to a time long after epoch
238 inode->i_atime.tv_sec = (int)be32_to_cpu(from->di_atime.t_sec);
239 inode->i_atime.tv_nsec = (int)be32_to_cpu(from->di_atime.t_nsec);
240 inode->i_mtime.tv_sec = (int)be32_to_cpu(from->di_mtime.t_sec);
241 inode->i_mtime.tv_nsec = (int)be32_to_cpu(from->di_mtime.t_nsec);
242 inode->i_ctime.tv_sec = (int)be32_to_cpu(from->di_ctime.t_sec);
243 inode->i_ctime.tv_nsec = (int)be32_to_cpu(from->di_ctime.t_nsec);
244 inode->i_generation = be32_to_cpu(from->di_gen);
245 inode->i_mode = be16_to_cpu(from->di_mode);
247 to->di_size = be64_to_cpu(from->di_size);
248 to->di_nblocks = be64_to_cpu(from->di_nblocks);
249 to->di_extsize = be32_to_cpu(from->di_extsize);
250 to->di_nextents = be32_to_cpu(from->di_nextents);
251 to->di_anextents = be16_to_cpu(from->di_anextents);
252 to->di_forkoff = from->di_forkoff;
253 to->di_aformat = from->di_aformat;
254 to->di_dmevmask = be32_to_cpu(from->di_dmevmask);
255 to->di_dmstate = be16_to_cpu(from->di_dmstate);
256 to->di_flags = be16_to_cpu(from->di_flags);
258 if (to->di_version == 3) {
259 inode_set_iversion_queried(inode,
260 be64_to_cpu(from->di_changecount));
261 to->di_crtime.t_sec = be32_to_cpu(from->di_crtime.t_sec);
262 to->di_crtime.t_nsec = be32_to_cpu(from->di_crtime.t_nsec);
263 to->di_flags2 = be64_to_cpu(from->di_flags2);
264 to->di_cowextsize = be32_to_cpu(from->di_cowextsize);
270 struct xfs_inode *ip,
271 struct xfs_dinode *to,
274 struct xfs_icdinode *from = &ip->i_d;
275 struct inode *inode = VFS_I(ip);
277 to->di_magic = cpu_to_be16(XFS_DINODE_MAGIC);
280 to->di_version = from->di_version;
281 to->di_format = from->di_format;
282 to->di_uid = cpu_to_be32(from->di_uid);
283 to->di_gid = cpu_to_be32(from->di_gid);
284 to->di_projid_lo = cpu_to_be16(from->di_projid_lo);
285 to->di_projid_hi = cpu_to_be16(from->di_projid_hi);
287 memset(to->di_pad, 0, sizeof(to->di_pad));
288 to->di_atime.t_sec = cpu_to_be32(inode->i_atime.tv_sec);
289 to->di_atime.t_nsec = cpu_to_be32(inode->i_atime.tv_nsec);
290 to->di_mtime.t_sec = cpu_to_be32(inode->i_mtime.tv_sec);
291 to->di_mtime.t_nsec = cpu_to_be32(inode->i_mtime.tv_nsec);
292 to->di_ctime.t_sec = cpu_to_be32(inode->i_ctime.tv_sec);
293 to->di_ctime.t_nsec = cpu_to_be32(inode->i_ctime.tv_nsec);
294 to->di_nlink = cpu_to_be32(inode->i_nlink);
295 to->di_gen = cpu_to_be32(inode->i_generation);
296 to->di_mode = cpu_to_be16(inode->i_mode);
298 to->di_size = cpu_to_be64(from->di_size);
299 to->di_nblocks = cpu_to_be64(from->di_nblocks);
300 to->di_extsize = cpu_to_be32(from->di_extsize);
301 to->di_nextents = cpu_to_be32(from->di_nextents);
302 to->di_anextents = cpu_to_be16(from->di_anextents);
303 to->di_forkoff = from->di_forkoff;
304 to->di_aformat = from->di_aformat;
305 to->di_dmevmask = cpu_to_be32(from->di_dmevmask);
306 to->di_dmstate = cpu_to_be16(from->di_dmstate);
307 to->di_flags = cpu_to_be16(from->di_flags);
309 if (from->di_version == 3) {
310 to->di_changecount = cpu_to_be64(inode_peek_iversion(inode));
311 to->di_crtime.t_sec = cpu_to_be32(from->di_crtime.t_sec);
312 to->di_crtime.t_nsec = cpu_to_be32(from->di_crtime.t_nsec);
313 to->di_flags2 = cpu_to_be64(from->di_flags2);
314 to->di_cowextsize = cpu_to_be32(from->di_cowextsize);
315 to->di_ino = cpu_to_be64(ip->i_ino);
316 to->di_lsn = cpu_to_be64(lsn);
317 memset(to->di_pad2, 0, sizeof(to->di_pad2));
318 uuid_copy(&to->di_uuid, &ip->i_mount->m_sb.sb_meta_uuid);
319 to->di_flushiter = 0;
321 to->di_flushiter = cpu_to_be16(from->di_flushiter);
326 xfs_log_dinode_to_disk(
327 struct xfs_log_dinode *from,
328 struct xfs_dinode *to)
330 to->di_magic = cpu_to_be16(from->di_magic);
331 to->di_mode = cpu_to_be16(from->di_mode);
332 to->di_version = from->di_version;
333 to->di_format = from->di_format;
335 to->di_uid = cpu_to_be32(from->di_uid);
336 to->di_gid = cpu_to_be32(from->di_gid);
337 to->di_nlink = cpu_to_be32(from->di_nlink);
338 to->di_projid_lo = cpu_to_be16(from->di_projid_lo);
339 to->di_projid_hi = cpu_to_be16(from->di_projid_hi);
340 memcpy(to->di_pad, from->di_pad, sizeof(to->di_pad));
342 to->di_atime.t_sec = cpu_to_be32(from->di_atime.t_sec);
343 to->di_atime.t_nsec = cpu_to_be32(from->di_atime.t_nsec);
344 to->di_mtime.t_sec = cpu_to_be32(from->di_mtime.t_sec);
345 to->di_mtime.t_nsec = cpu_to_be32(from->di_mtime.t_nsec);
346 to->di_ctime.t_sec = cpu_to_be32(from->di_ctime.t_sec);
347 to->di_ctime.t_nsec = cpu_to_be32(from->di_ctime.t_nsec);
349 to->di_size = cpu_to_be64(from->di_size);
350 to->di_nblocks = cpu_to_be64(from->di_nblocks);
351 to->di_extsize = cpu_to_be32(from->di_extsize);
352 to->di_nextents = cpu_to_be32(from->di_nextents);
353 to->di_anextents = cpu_to_be16(from->di_anextents);
354 to->di_forkoff = from->di_forkoff;
355 to->di_aformat = from->di_aformat;
356 to->di_dmevmask = cpu_to_be32(from->di_dmevmask);
357 to->di_dmstate = cpu_to_be16(from->di_dmstate);
358 to->di_flags = cpu_to_be16(from->di_flags);
359 to->di_gen = cpu_to_be32(from->di_gen);
361 if (from->di_version == 3) {
362 to->di_changecount = cpu_to_be64(from->di_changecount);
363 to->di_crtime.t_sec = cpu_to_be32(from->di_crtime.t_sec);
364 to->di_crtime.t_nsec = cpu_to_be32(from->di_crtime.t_nsec);
365 to->di_flags2 = cpu_to_be64(from->di_flags2);
366 to->di_cowextsize = cpu_to_be32(from->di_cowextsize);
367 to->di_ino = cpu_to_be64(from->di_ino);
368 to->di_lsn = cpu_to_be64(from->di_lsn);
369 memcpy(to->di_pad2, from->di_pad2, sizeof(to->di_pad2));
370 uuid_copy(&to->di_uuid, &from->di_uuid);
371 to->di_flushiter = 0;
373 to->di_flushiter = cpu_to_be16(from->di_flushiter);
379 struct xfs_mount *mp,
381 struct xfs_dinode *dip)
389 if (dip->di_magic != cpu_to_be16(XFS_DINODE_MAGIC))
390 return __this_address;
392 /* Verify v3 integrity information first */
393 if (dip->di_version >= 3) {
394 if (!xfs_sb_version_hascrc(&mp->m_sb))
395 return __this_address;
396 if (!xfs_verify_cksum((char *)dip, mp->m_sb.sb_inodesize,
398 return __this_address;
399 if (be64_to_cpu(dip->di_ino) != ino)
400 return __this_address;
401 if (!uuid_equal(&dip->di_uuid, &mp->m_sb.sb_meta_uuid))
402 return __this_address;
405 /* don't allow invalid i_size */
406 di_size = be64_to_cpu(dip->di_size);
407 if (di_size & (1ULL << 63))
408 return __this_address;
410 mode = be16_to_cpu(dip->di_mode);
411 if (mode && xfs_mode_to_ftype(mode) == XFS_DIR3_FT_UNKNOWN)
412 return __this_address;
414 /* No zero-length symlinks/dirs. */
415 if ((S_ISLNK(mode) || S_ISDIR(mode)) && di_size == 0)
416 return __this_address;
418 /* Fork checks carried over from xfs_iformat_fork */
420 be32_to_cpu(dip->di_nextents) + be16_to_cpu(dip->di_anextents) >
421 be64_to_cpu(dip->di_nblocks))
422 return __this_address;
424 if (mode && XFS_DFORK_BOFF(dip) > mp->m_sb.sb_inodesize)
425 return __this_address;
427 flags = be16_to_cpu(dip->di_flags);
429 if (mode && (flags & XFS_DIFLAG_REALTIME) && !mp->m_rtdev_targp)
430 return __this_address;
432 /* Do we have appropriate data fork formats for the mode? */
433 switch (mode & S_IFMT) {
438 if (dip->di_format != XFS_DINODE_FMT_DEV)
439 return __this_address;
444 switch (dip->di_format) {
445 case XFS_DINODE_FMT_LOCAL:
447 * no local regular files yet
450 return __this_address;
451 if (di_size > XFS_DFORK_DSIZE(dip, mp))
452 return __this_address;
453 if (dip->di_nextents)
454 return __this_address;
456 case XFS_DINODE_FMT_EXTENTS:
457 case XFS_DINODE_FMT_BTREE:
460 return __this_address;
464 /* Uninitialized inode ok. */
467 return __this_address;
470 if (XFS_DFORK_Q(dip)) {
471 switch (dip->di_aformat) {
472 case XFS_DINODE_FMT_LOCAL:
473 if (dip->di_anextents)
474 return __this_address;
476 case XFS_DINODE_FMT_EXTENTS:
477 case XFS_DINODE_FMT_BTREE:
480 return __this_address;
484 * If there is no fork offset, this may be a freshly-made inode
485 * in a new disk cluster, in which case di_aformat is zeroed.
486 * Otherwise, such an inode must be in EXTENTS format; this goes
487 * for freed inodes as well.
489 switch (dip->di_aformat) {
491 case XFS_DINODE_FMT_EXTENTS:
494 return __this_address;
496 if (dip->di_anextents)
497 return __this_address;
500 /* extent size hint validation */
501 fa = xfs_inode_validate_extsize(mp, be32_to_cpu(dip->di_extsize),
506 /* only version 3 or greater inodes are extensively verified here */
507 if (dip->di_version < 3)
510 flags2 = be64_to_cpu(dip->di_flags2);
512 /* don't allow reflink/cowextsize if we don't have reflink */
513 if ((flags2 & (XFS_DIFLAG2_REFLINK | XFS_DIFLAG2_COWEXTSIZE)) &&
514 !xfs_sb_version_hasreflink(&mp->m_sb))
515 return __this_address;
517 /* only regular files get reflink */
518 if ((flags2 & XFS_DIFLAG2_REFLINK) && (mode & S_IFMT) != S_IFREG)
519 return __this_address;
521 /* don't let reflink and realtime mix */
522 if ((flags2 & XFS_DIFLAG2_REFLINK) && (flags & XFS_DIFLAG_REALTIME))
523 return __this_address;
525 /* don't let reflink and dax mix */
526 if ((flags2 & XFS_DIFLAG2_REFLINK) && (flags2 & XFS_DIFLAG2_DAX))
527 return __this_address;
529 /* COW extent size hint validation */
530 fa = xfs_inode_validate_cowextsize(mp, be32_to_cpu(dip->di_cowextsize),
531 mode, flags, flags2);
540 struct xfs_mount *mp,
541 struct xfs_dinode *dip)
545 if (dip->di_version < 3)
548 ASSERT(xfs_sb_version_hascrc(&mp->m_sb));
549 crc = xfs_start_cksum_update((char *)dip, mp->m_sb.sb_inodesize,
551 dip->di_crc = xfs_end_cksum(crc);
555 * Read the disk inode attributes into the in-core inode structure.
557 * For version 5 superblocks, if we are initialising a new inode and we are not
558 * utilising the XFS_MOUNT_IKEEP inode cluster mode, we can simple build the new
559 * inode core with a random generation number. If we are keeping inodes around,
560 * we need to read the inode cluster to get the existing generation number off
561 * disk. Further, if we are using version 4 superblocks (i.e. v1/v2 inode
562 * format) then log recovery is dependent on the di_flushiter field being
563 * initialised from the current on-disk value and hence we must also read the
579 * Fill in the location information in the in-core inode.
581 error = xfs_imap(mp, tp, ip->i_ino, &ip->i_imap, iget_flags);
585 /* shortcut IO on inode allocation if possible */
586 if ((iget_flags & XFS_IGET_CREATE) &&
587 xfs_sb_version_hascrc(&mp->m_sb) &&
588 !(mp->m_flags & XFS_MOUNT_IKEEP)) {
589 /* initialise the on-disk inode core */
590 memset(&ip->i_d, 0, sizeof(ip->i_d));
591 VFS_I(ip)->i_generation = prandom_u32();
592 ip->i_d.di_version = 3;
597 * Get pointers to the on-disk inode and the buffer containing it.
599 error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &bp, 0, iget_flags);
603 /* even unallocated inodes are verified */
604 fa = xfs_dinode_verify(mp, ip->i_ino, dip);
606 xfs_inode_verifier_error(ip, -EFSCORRUPTED, "dinode", dip,
608 error = -EFSCORRUPTED;
613 * If the on-disk inode is already linked to a directory
614 * entry, copy all of the inode into the in-core inode.
615 * xfs_iformat_fork() handles copying in the inode format
616 * specific information.
617 * Otherwise, just get the truly permanent information.
620 xfs_inode_from_disk(ip, dip);
621 error = xfs_iformat_fork(ip, dip);
624 xfs_alert(mp, "%s: xfs_iformat() returned error %d",
631 * Partial initialisation of the in-core inode. Just the bits
632 * that xfs_ialloc won't overwrite or relies on being correct.
634 ip->i_d.di_version = dip->di_version;
635 VFS_I(ip)->i_generation = be32_to_cpu(dip->di_gen);
636 ip->i_d.di_flushiter = be16_to_cpu(dip->di_flushiter);
639 * Make sure to pull in the mode here as well in
640 * case the inode is released without being used.
641 * This ensures that xfs_inactive() will see that
642 * the inode is already free and not try to mess
643 * with the uninitialized part of it.
645 VFS_I(ip)->i_mode = 0;
648 ASSERT(ip->i_d.di_version >= 2);
649 ip->i_delayed_blks = 0;
652 * Mark the buffer containing the inode as something to keep
653 * around for a while. This helps to keep recently accessed
654 * meta-data in-core longer.
656 xfs_buf_set_ref(bp, XFS_INO_REF);
659 * Use xfs_trans_brelse() to release the buffer containing the on-disk
660 * inode, because it was acquired with xfs_trans_read_buf() in
661 * xfs_imap_to_bp() above. If tp is NULL, this is just a normal
662 * brelse(). If we're within a transaction, then xfs_trans_brelse()
663 * will only release the buffer if it is not dirty within the
664 * transaction. It will be OK to release the buffer in this case,
665 * because inodes on disk are never destroyed and we will be locking the
666 * new in-core inode before putting it in the cache where other
667 * processes can find it. Thus we don't have to worry about the inode
668 * being changed just because we released the buffer.
671 xfs_trans_brelse(tp, bp);
676 * Validate di_extsize hint.
678 * The rules are documented at xfs_ioctl_setattr_check_extsize().
679 * These functions must be kept in sync with each other.
682 xfs_inode_validate_extsize(
683 struct xfs_mount *mp,
691 uint32_t extsize_bytes;
692 uint32_t blocksize_bytes;
694 rt_flag = (flags & XFS_DIFLAG_REALTIME);
695 hint_flag = (flags & XFS_DIFLAG_EXTSIZE);
696 inherit_flag = (flags & XFS_DIFLAG_EXTSZINHERIT);
697 extsize_bytes = XFS_FSB_TO_B(mp, extsize);
700 blocksize_bytes = mp->m_sb.sb_rextsize << mp->m_sb.sb_blocklog;
702 blocksize_bytes = mp->m_sb.sb_blocksize;
704 if ((hint_flag || inherit_flag) && !(S_ISDIR(mode) || S_ISREG(mode)))
705 return __this_address;
707 if (hint_flag && !S_ISREG(mode))
708 return __this_address;
710 if (inherit_flag && !S_ISDIR(mode))
711 return __this_address;
713 if ((hint_flag || inherit_flag) && extsize == 0)
714 return __this_address;
716 if (!(hint_flag || inherit_flag) && extsize != 0)
717 return __this_address;
719 if (extsize_bytes % blocksize_bytes)
720 return __this_address;
722 if (extsize > MAXEXTLEN)
723 return __this_address;
725 if (!rt_flag && extsize > mp->m_sb.sb_agblocks / 2)
726 return __this_address;
732 * Validate di_cowextsize hint.
734 * The rules are documented at xfs_ioctl_setattr_check_cowextsize().
735 * These functions must be kept in sync with each other.
738 xfs_inode_validate_cowextsize(
739 struct xfs_mount *mp,
747 uint32_t cowextsize_bytes;
749 rt_flag = (flags & XFS_DIFLAG_REALTIME);
750 hint_flag = (flags2 & XFS_DIFLAG2_COWEXTSIZE);
751 cowextsize_bytes = XFS_FSB_TO_B(mp, cowextsize);
753 if (hint_flag && !xfs_sb_version_hasreflink(&mp->m_sb))
754 return __this_address;
756 if (hint_flag && !(S_ISDIR(mode) || S_ISREG(mode)))
757 return __this_address;
759 if (hint_flag && cowextsize == 0)
760 return __this_address;
762 if (!hint_flag && cowextsize != 0)
763 return __this_address;
765 if (hint_flag && rt_flag)
766 return __this_address;
768 if (cowextsize_bytes % mp->m_sb.sb_blocksize)
769 return __this_address;
771 if (cowextsize > MAXEXTLEN)
772 return __this_address;
774 if (cowextsize > mp->m_sb.sb_agblocks / 2)
775 return __this_address;