xfs: factor out dir2 data block reading
[linux-2.6.git] / fs / xfs / xfs_dir2_data.c
blob0ef04f1bf51123722b09d3ca1502715c1d44a1a4
1 /*
2 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
3 * All Rights Reserved.
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation.
9 * This program is distributed in the hope that it would be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18 #include "xfs.h"
19 #include "xfs_fs.h"
20 #include "xfs_types.h"
21 #include "xfs_log.h"
22 #include "xfs_trans.h"
23 #include "xfs_sb.h"
24 #include "xfs_ag.h"
25 #include "xfs_mount.h"
26 #include "xfs_da_btree.h"
27 #include "xfs_bmap_btree.h"
28 #include "xfs_dinode.h"
29 #include "xfs_inode.h"
30 #include "xfs_dir2_format.h"
31 #include "xfs_dir2_priv.h"
32 #include "xfs_error.h"
34 STATIC xfs_dir2_data_free_t *
35 xfs_dir2_data_freefind(xfs_dir2_data_hdr_t *hdr, xfs_dir2_data_unused_t *dup);
38 * Check the consistency of the data block.
39 * The input can also be a block-format directory.
40 * Return 0 is the buffer is good, otherwise an error.
42 int
43 __xfs_dir2_data_check(
44 struct xfs_inode *dp, /* incore inode pointer */
45 struct xfs_buf *bp) /* data block's buffer */
47 xfs_dir2_dataptr_t addr; /* addr for leaf lookup */
48 xfs_dir2_data_free_t *bf; /* bestfree table */
49 xfs_dir2_block_tail_t *btp=NULL; /* block tail */
50 int count; /* count of entries found */
51 xfs_dir2_data_hdr_t *hdr; /* data block header */
52 xfs_dir2_data_entry_t *dep; /* data entry */
53 xfs_dir2_data_free_t *dfp; /* bestfree entry */
54 xfs_dir2_data_unused_t *dup; /* unused entry */
55 char *endp; /* end of useful data */
56 int freeseen; /* mask of bestfrees seen */
57 xfs_dahash_t hash; /* hash of current name */
58 int i; /* leaf index */
59 int lastfree; /* last entry was unused */
60 xfs_dir2_leaf_entry_t *lep=NULL; /* block leaf entries */
61 xfs_mount_t *mp; /* filesystem mount point */
62 char *p; /* current data position */
63 int stale; /* count of stale leaves */
64 struct xfs_name name;
66 mp = bp->b_target->bt_mount;
67 hdr = bp->b_addr;
68 bf = hdr->bestfree;
69 p = (char *)(hdr + 1);
71 switch (hdr->magic) {
72 case cpu_to_be32(XFS_DIR2_BLOCK_MAGIC):
73 btp = xfs_dir2_block_tail_p(mp, hdr);
74 lep = xfs_dir2_block_leaf_p(btp);
75 endp = (char *)lep;
76 break;
77 case cpu_to_be32(XFS_DIR2_DATA_MAGIC):
78 endp = (char *)hdr + mp->m_dirblksize;
79 break;
80 default:
81 XFS_ERROR_REPORT("Bad Magic", XFS_ERRLEVEL_LOW, mp);
82 return EFSCORRUPTED;
85 count = lastfree = freeseen = 0;
87 * Account for zero bestfree entries.
89 if (!bf[0].length) {
90 XFS_WANT_CORRUPTED_RETURN(!bf[0].offset);
91 freeseen |= 1 << 0;
93 if (!bf[1].length) {
94 XFS_WANT_CORRUPTED_RETURN(!bf[1].offset);
95 freeseen |= 1 << 1;
97 if (!bf[2].length) {
98 XFS_WANT_CORRUPTED_RETURN(!bf[2].offset);
99 freeseen |= 1 << 2;
102 XFS_WANT_CORRUPTED_RETURN(be16_to_cpu(bf[0].length) >=
103 be16_to_cpu(bf[1].length));
104 XFS_WANT_CORRUPTED_RETURN(be16_to_cpu(bf[1].length) >=
105 be16_to_cpu(bf[2].length));
107 * Loop over the data/unused entries.
109 while (p < endp) {
110 dup = (xfs_dir2_data_unused_t *)p;
112 * If it's unused, look for the space in the bestfree table.
113 * If we find it, account for that, else make sure it
114 * doesn't need to be there.
116 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
117 XFS_WANT_CORRUPTED_RETURN(lastfree == 0);
118 XFS_WANT_CORRUPTED_RETURN(
119 be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)) ==
120 (char *)dup - (char *)hdr);
121 dfp = xfs_dir2_data_freefind(hdr, dup);
122 if (dfp) {
123 i = (int)(dfp - bf);
124 XFS_WANT_CORRUPTED_RETURN(
125 (freeseen & (1 << i)) == 0);
126 freeseen |= 1 << i;
127 } else {
128 XFS_WANT_CORRUPTED_RETURN(
129 be16_to_cpu(dup->length) <=
130 be16_to_cpu(bf[2].length));
132 p += be16_to_cpu(dup->length);
133 lastfree = 1;
134 continue;
137 * It's a real entry. Validate the fields.
138 * If this is a block directory then make sure it's
139 * in the leaf section of the block.
140 * The linear search is crude but this is DEBUG code.
142 dep = (xfs_dir2_data_entry_t *)p;
143 XFS_WANT_CORRUPTED_RETURN(dep->namelen != 0);
144 XFS_WANT_CORRUPTED_RETURN(
145 !xfs_dir_ino_validate(mp, be64_to_cpu(dep->inumber)));
146 XFS_WANT_CORRUPTED_RETURN(
147 be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)) ==
148 (char *)dep - (char *)hdr);
149 count++;
150 lastfree = 0;
151 if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
152 addr = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
153 (xfs_dir2_data_aoff_t)
154 ((char *)dep - (char *)hdr));
155 name.name = dep->name;
156 name.len = dep->namelen;
157 hash = mp->m_dirnameops->hashname(&name);
158 for (i = 0; i < be32_to_cpu(btp->count); i++) {
159 if (be32_to_cpu(lep[i].address) == addr &&
160 be32_to_cpu(lep[i].hashval) == hash)
161 break;
163 XFS_WANT_CORRUPTED_RETURN(i < be32_to_cpu(btp->count));
165 p += xfs_dir2_data_entsize(dep->namelen);
168 * Need to have seen all the entries and all the bestfree slots.
170 XFS_WANT_CORRUPTED_RETURN(freeseen == 7);
171 if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
172 for (i = stale = 0; i < be32_to_cpu(btp->count); i++) {
173 if (lep[i].address ==
174 cpu_to_be32(XFS_DIR2_NULL_DATAPTR))
175 stale++;
176 if (i > 0)
177 XFS_WANT_CORRUPTED_RETURN(
178 be32_to_cpu(lep[i].hashval) >=
179 be32_to_cpu(lep[i - 1].hashval));
181 XFS_WANT_CORRUPTED_RETURN(count ==
182 be32_to_cpu(btp->count) - be32_to_cpu(btp->stale));
183 XFS_WANT_CORRUPTED_RETURN(stale == be32_to_cpu(btp->stale));
185 return 0;
188 static void
189 xfs_dir2_data_verify(
190 struct xfs_buf *bp)
192 struct xfs_mount *mp = bp->b_target->bt_mount;
193 struct xfs_dir2_data_hdr *hdr = bp->b_addr;
194 int block_ok = 0;
196 block_ok = hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC);
197 block_ok = block_ok && __xfs_dir2_data_check(NULL, bp) == 0;
199 if (!block_ok) {
200 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, hdr);
201 xfs_buf_ioerror(bp, EFSCORRUPTED);
204 bp->b_iodone = NULL;
205 xfs_buf_ioend(bp, 0);
209 xfs_dir2_data_read(
210 struct xfs_trans *tp,
211 struct xfs_inode *dp,
212 xfs_dablk_t bno,
213 xfs_daddr_t mapped_bno,
214 struct xfs_buf **bpp)
216 return xfs_da_read_buf(tp, dp, bno, mapped_bno, bpp,
217 XFS_DATA_FORK, xfs_dir2_data_verify);
221 * Given a data block and an unused entry from that block,
222 * return the bestfree entry if any that corresponds to it.
224 STATIC xfs_dir2_data_free_t *
225 xfs_dir2_data_freefind(
226 xfs_dir2_data_hdr_t *hdr, /* data block */
227 xfs_dir2_data_unused_t *dup) /* data unused entry */
229 xfs_dir2_data_free_t *dfp; /* bestfree entry */
230 xfs_dir2_data_aoff_t off; /* offset value needed */
231 #if defined(DEBUG) && defined(__KERNEL__)
232 int matched; /* matched the value */
233 int seenzero; /* saw a 0 bestfree entry */
234 #endif
236 off = (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr);
237 #if defined(DEBUG) && defined(__KERNEL__)
239 * Validate some consistency in the bestfree table.
240 * Check order, non-overlapping entries, and if we find the
241 * one we're looking for it has to be exact.
243 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
244 hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
245 for (dfp = &hdr->bestfree[0], seenzero = matched = 0;
246 dfp < &hdr->bestfree[XFS_DIR2_DATA_FD_COUNT];
247 dfp++) {
248 if (!dfp->offset) {
249 ASSERT(!dfp->length);
250 seenzero = 1;
251 continue;
253 ASSERT(seenzero == 0);
254 if (be16_to_cpu(dfp->offset) == off) {
255 matched = 1;
256 ASSERT(dfp->length == dup->length);
257 } else if (off < be16_to_cpu(dfp->offset))
258 ASSERT(off + be16_to_cpu(dup->length) <= be16_to_cpu(dfp->offset));
259 else
260 ASSERT(be16_to_cpu(dfp->offset) + be16_to_cpu(dfp->length) <= off);
261 ASSERT(matched || be16_to_cpu(dfp->length) >= be16_to_cpu(dup->length));
262 if (dfp > &hdr->bestfree[0])
263 ASSERT(be16_to_cpu(dfp[-1].length) >= be16_to_cpu(dfp[0].length));
265 #endif
267 * If this is smaller than the smallest bestfree entry,
268 * it can't be there since they're sorted.
270 if (be16_to_cpu(dup->length) <
271 be16_to_cpu(hdr->bestfree[XFS_DIR2_DATA_FD_COUNT - 1].length))
272 return NULL;
274 * Look at the three bestfree entries for our guy.
276 for (dfp = &hdr->bestfree[0];
277 dfp < &hdr->bestfree[XFS_DIR2_DATA_FD_COUNT];
278 dfp++) {
279 if (!dfp->offset)
280 return NULL;
281 if (be16_to_cpu(dfp->offset) == off)
282 return dfp;
285 * Didn't find it. This only happens if there are duplicate lengths.
287 return NULL;
291 * Insert an unused-space entry into the bestfree table.
293 xfs_dir2_data_free_t * /* entry inserted */
294 xfs_dir2_data_freeinsert(
295 xfs_dir2_data_hdr_t *hdr, /* data block pointer */
296 xfs_dir2_data_unused_t *dup, /* unused space */
297 int *loghead) /* log the data header (out) */
299 xfs_dir2_data_free_t *dfp; /* bestfree table pointer */
300 xfs_dir2_data_free_t new; /* new bestfree entry */
302 #ifdef __KERNEL__
303 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
304 hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
305 #endif
306 dfp = hdr->bestfree;
307 new.length = dup->length;
308 new.offset = cpu_to_be16((char *)dup - (char *)hdr);
311 * Insert at position 0, 1, or 2; or not at all.
313 if (be16_to_cpu(new.length) > be16_to_cpu(dfp[0].length)) {
314 dfp[2] = dfp[1];
315 dfp[1] = dfp[0];
316 dfp[0] = new;
317 *loghead = 1;
318 return &dfp[0];
320 if (be16_to_cpu(new.length) > be16_to_cpu(dfp[1].length)) {
321 dfp[2] = dfp[1];
322 dfp[1] = new;
323 *loghead = 1;
324 return &dfp[1];
326 if (be16_to_cpu(new.length) > be16_to_cpu(dfp[2].length)) {
327 dfp[2] = new;
328 *loghead = 1;
329 return &dfp[2];
331 return NULL;
335 * Remove a bestfree entry from the table.
337 STATIC void
338 xfs_dir2_data_freeremove(
339 xfs_dir2_data_hdr_t *hdr, /* data block header */
340 xfs_dir2_data_free_t *dfp, /* bestfree entry pointer */
341 int *loghead) /* out: log data header */
343 #ifdef __KERNEL__
344 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
345 hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
346 #endif
348 * It's the first entry, slide the next 2 up.
350 if (dfp == &hdr->bestfree[0]) {
351 hdr->bestfree[0] = hdr->bestfree[1];
352 hdr->bestfree[1] = hdr->bestfree[2];
355 * It's the second entry, slide the 3rd entry up.
357 else if (dfp == &hdr->bestfree[1])
358 hdr->bestfree[1] = hdr->bestfree[2];
360 * Must be the last entry.
362 else
363 ASSERT(dfp == &hdr->bestfree[2]);
365 * Clear the 3rd entry, must be zero now.
367 hdr->bestfree[2].length = 0;
368 hdr->bestfree[2].offset = 0;
369 *loghead = 1;
373 * Given a data block, reconstruct its bestfree map.
375 void
376 xfs_dir2_data_freescan(
377 xfs_mount_t *mp, /* filesystem mount point */
378 xfs_dir2_data_hdr_t *hdr, /* data block header */
379 int *loghead) /* out: log data header */
381 xfs_dir2_block_tail_t *btp; /* block tail */
382 xfs_dir2_data_entry_t *dep; /* active data entry */
383 xfs_dir2_data_unused_t *dup; /* unused data entry */
384 char *endp; /* end of block's data */
385 char *p; /* current entry pointer */
387 #ifdef __KERNEL__
388 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
389 hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
390 #endif
392 * Start by clearing the table.
394 memset(hdr->bestfree, 0, sizeof(hdr->bestfree));
395 *loghead = 1;
397 * Set up pointers.
399 p = (char *)(hdr + 1);
400 if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
401 btp = xfs_dir2_block_tail_p(mp, hdr);
402 endp = (char *)xfs_dir2_block_leaf_p(btp);
403 } else
404 endp = (char *)hdr + mp->m_dirblksize;
406 * Loop over the block's entries.
408 while (p < endp) {
409 dup = (xfs_dir2_data_unused_t *)p;
411 * If it's a free entry, insert it.
413 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
414 ASSERT((char *)dup - (char *)hdr ==
415 be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
416 xfs_dir2_data_freeinsert(hdr, dup, loghead);
417 p += be16_to_cpu(dup->length);
420 * For active entries, check their tags and skip them.
422 else {
423 dep = (xfs_dir2_data_entry_t *)p;
424 ASSERT((char *)dep - (char *)hdr ==
425 be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)));
426 p += xfs_dir2_data_entsize(dep->namelen);
432 * Initialize a data block at the given block number in the directory.
433 * Give back the buffer for the created block.
435 int /* error */
436 xfs_dir2_data_init(
437 xfs_da_args_t *args, /* directory operation args */
438 xfs_dir2_db_t blkno, /* logical dir block number */
439 struct xfs_buf **bpp) /* output block buffer */
441 struct xfs_buf *bp; /* block buffer */
442 xfs_dir2_data_hdr_t *hdr; /* data block header */
443 xfs_inode_t *dp; /* incore directory inode */
444 xfs_dir2_data_unused_t *dup; /* unused entry pointer */
445 int error; /* error return value */
446 int i; /* bestfree index */
447 xfs_mount_t *mp; /* filesystem mount point */
448 xfs_trans_t *tp; /* transaction pointer */
449 int t; /* temp */
451 dp = args->dp;
452 mp = dp->i_mount;
453 tp = args->trans;
455 * Get the buffer set up for the block.
457 error = xfs_da_get_buf(tp, dp, xfs_dir2_db_to_da(mp, blkno), -1, &bp,
458 XFS_DATA_FORK);
459 if (error) {
460 return error;
462 ASSERT(bp != NULL);
465 * Initialize the header.
467 hdr = bp->b_addr;
468 hdr->magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);
469 hdr->bestfree[0].offset = cpu_to_be16(sizeof(*hdr));
470 for (i = 1; i < XFS_DIR2_DATA_FD_COUNT; i++) {
471 hdr->bestfree[i].length = 0;
472 hdr->bestfree[i].offset = 0;
476 * Set up an unused entry for the block's body.
478 dup = (xfs_dir2_data_unused_t *)(hdr + 1);
479 dup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
481 t = mp->m_dirblksize - (uint)sizeof(*hdr);
482 hdr->bestfree[0].length = cpu_to_be16(t);
483 dup->length = cpu_to_be16(t);
484 *xfs_dir2_data_unused_tag_p(dup) = cpu_to_be16((char *)dup - (char *)hdr);
486 * Log it and return it.
488 xfs_dir2_data_log_header(tp, bp);
489 xfs_dir2_data_log_unused(tp, bp, dup);
490 *bpp = bp;
491 return 0;
495 * Log an active data entry from the block.
497 void
498 xfs_dir2_data_log_entry(
499 struct xfs_trans *tp,
500 struct xfs_buf *bp,
501 xfs_dir2_data_entry_t *dep) /* data entry pointer */
503 xfs_dir2_data_hdr_t *hdr = bp->b_addr;
505 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
506 hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
508 xfs_trans_log_buf(tp, bp, (uint)((char *)dep - (char *)hdr),
509 (uint)((char *)(xfs_dir2_data_entry_tag_p(dep) + 1) -
510 (char *)hdr - 1));
514 * Log a data block header.
516 void
517 xfs_dir2_data_log_header(
518 struct xfs_trans *tp,
519 struct xfs_buf *bp)
521 xfs_dir2_data_hdr_t *hdr = bp->b_addr;
523 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
524 hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
526 xfs_trans_log_buf(tp, bp, 0, sizeof(*hdr) - 1);
530 * Log a data unused entry.
532 void
533 xfs_dir2_data_log_unused(
534 struct xfs_trans *tp,
535 struct xfs_buf *bp,
536 xfs_dir2_data_unused_t *dup) /* data unused pointer */
538 xfs_dir2_data_hdr_t *hdr = bp->b_addr;
540 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
541 hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
544 * Log the first part of the unused entry.
546 xfs_trans_log_buf(tp, bp, (uint)((char *)dup - (char *)hdr),
547 (uint)((char *)&dup->length + sizeof(dup->length) -
548 1 - (char *)hdr));
550 * Log the end (tag) of the unused entry.
552 xfs_trans_log_buf(tp, bp,
553 (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)hdr),
554 (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)hdr +
555 sizeof(xfs_dir2_data_off_t) - 1));
559 * Make a byte range in the data block unused.
560 * Its current contents are unimportant.
562 void
563 xfs_dir2_data_make_free(
564 struct xfs_trans *tp,
565 struct xfs_buf *bp,
566 xfs_dir2_data_aoff_t offset, /* starting byte offset */
567 xfs_dir2_data_aoff_t len, /* length in bytes */
568 int *needlogp, /* out: log header */
569 int *needscanp) /* out: regen bestfree */
571 xfs_dir2_data_hdr_t *hdr; /* data block pointer */
572 xfs_dir2_data_free_t *dfp; /* bestfree pointer */
573 char *endptr; /* end of data area */
574 xfs_mount_t *mp; /* filesystem mount point */
575 int needscan; /* need to regen bestfree */
576 xfs_dir2_data_unused_t *newdup; /* new unused entry */
577 xfs_dir2_data_unused_t *postdup; /* unused entry after us */
578 xfs_dir2_data_unused_t *prevdup; /* unused entry before us */
580 mp = tp->t_mountp;
581 hdr = bp->b_addr;
584 * Figure out where the end of the data area is.
586 if (hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC))
587 endptr = (char *)hdr + mp->m_dirblksize;
588 else {
589 xfs_dir2_block_tail_t *btp; /* block tail */
591 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
592 btp = xfs_dir2_block_tail_p(mp, hdr);
593 endptr = (char *)xfs_dir2_block_leaf_p(btp);
596 * If this isn't the start of the block, then back up to
597 * the previous entry and see if it's free.
599 if (offset > sizeof(*hdr)) {
600 __be16 *tagp; /* tag just before us */
602 tagp = (__be16 *)((char *)hdr + offset) - 1;
603 prevdup = (xfs_dir2_data_unused_t *)((char *)hdr + be16_to_cpu(*tagp));
604 if (be16_to_cpu(prevdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
605 prevdup = NULL;
606 } else
607 prevdup = NULL;
609 * If this isn't the end of the block, see if the entry after
610 * us is free.
612 if ((char *)hdr + offset + len < endptr) {
613 postdup =
614 (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
615 if (be16_to_cpu(postdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
616 postdup = NULL;
617 } else
618 postdup = NULL;
619 ASSERT(*needscanp == 0);
620 needscan = 0;
622 * Previous and following entries are both free,
623 * merge everything into a single free entry.
625 if (prevdup && postdup) {
626 xfs_dir2_data_free_t *dfp2; /* another bestfree pointer */
629 * See if prevdup and/or postdup are in bestfree table.
631 dfp = xfs_dir2_data_freefind(hdr, prevdup);
632 dfp2 = xfs_dir2_data_freefind(hdr, postdup);
634 * We need a rescan unless there are exactly 2 free entries
635 * namely our two. Then we know what's happening, otherwise
636 * since the third bestfree is there, there might be more
637 * entries.
639 needscan = (hdr->bestfree[2].length != 0);
641 * Fix up the new big freespace.
643 be16_add_cpu(&prevdup->length, len + be16_to_cpu(postdup->length));
644 *xfs_dir2_data_unused_tag_p(prevdup) =
645 cpu_to_be16((char *)prevdup - (char *)hdr);
646 xfs_dir2_data_log_unused(tp, bp, prevdup);
647 if (!needscan) {
649 * Has to be the case that entries 0 and 1 are
650 * dfp and dfp2 (don't know which is which), and
651 * entry 2 is empty.
652 * Remove entry 1 first then entry 0.
654 ASSERT(dfp && dfp2);
655 if (dfp == &hdr->bestfree[1]) {
656 dfp = &hdr->bestfree[0];
657 ASSERT(dfp2 == dfp);
658 dfp2 = &hdr->bestfree[1];
660 xfs_dir2_data_freeremove(hdr, dfp2, needlogp);
661 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
663 * Now insert the new entry.
665 dfp = xfs_dir2_data_freeinsert(hdr, prevdup, needlogp);
666 ASSERT(dfp == &hdr->bestfree[0]);
667 ASSERT(dfp->length == prevdup->length);
668 ASSERT(!dfp[1].length);
669 ASSERT(!dfp[2].length);
673 * The entry before us is free, merge with it.
675 else if (prevdup) {
676 dfp = xfs_dir2_data_freefind(hdr, prevdup);
677 be16_add_cpu(&prevdup->length, len);
678 *xfs_dir2_data_unused_tag_p(prevdup) =
679 cpu_to_be16((char *)prevdup - (char *)hdr);
680 xfs_dir2_data_log_unused(tp, bp, prevdup);
682 * If the previous entry was in the table, the new entry
683 * is longer, so it will be in the table too. Remove
684 * the old one and add the new one.
686 if (dfp) {
687 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
688 xfs_dir2_data_freeinsert(hdr, prevdup, needlogp);
691 * Otherwise we need a scan if the new entry is big enough.
693 else {
694 needscan = be16_to_cpu(prevdup->length) >
695 be16_to_cpu(hdr->bestfree[2].length);
699 * The following entry is free, merge with it.
701 else if (postdup) {
702 dfp = xfs_dir2_data_freefind(hdr, postdup);
703 newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset);
704 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
705 newdup->length = cpu_to_be16(len + be16_to_cpu(postdup->length));
706 *xfs_dir2_data_unused_tag_p(newdup) =
707 cpu_to_be16((char *)newdup - (char *)hdr);
708 xfs_dir2_data_log_unused(tp, bp, newdup);
710 * If the following entry was in the table, the new entry
711 * is longer, so it will be in the table too. Remove
712 * the old one and add the new one.
714 if (dfp) {
715 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
716 xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
719 * Otherwise we need a scan if the new entry is big enough.
721 else {
722 needscan = be16_to_cpu(newdup->length) >
723 be16_to_cpu(hdr->bestfree[2].length);
727 * Neither neighbor is free. Make a new entry.
729 else {
730 newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset);
731 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
732 newdup->length = cpu_to_be16(len);
733 *xfs_dir2_data_unused_tag_p(newdup) =
734 cpu_to_be16((char *)newdup - (char *)hdr);
735 xfs_dir2_data_log_unused(tp, bp, newdup);
736 xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
738 *needscanp = needscan;
742 * Take a byte range out of an existing unused space and make it un-free.
744 void
745 xfs_dir2_data_use_free(
746 struct xfs_trans *tp,
747 struct xfs_buf *bp,
748 xfs_dir2_data_unused_t *dup, /* unused entry */
749 xfs_dir2_data_aoff_t offset, /* starting offset to use */
750 xfs_dir2_data_aoff_t len, /* length to use */
751 int *needlogp, /* out: need to log header */
752 int *needscanp) /* out: need regen bestfree */
754 xfs_dir2_data_hdr_t *hdr; /* data block header */
755 xfs_dir2_data_free_t *dfp; /* bestfree pointer */
756 int matchback; /* matches end of freespace */
757 int matchfront; /* matches start of freespace */
758 int needscan; /* need to regen bestfree */
759 xfs_dir2_data_unused_t *newdup; /* new unused entry */
760 xfs_dir2_data_unused_t *newdup2; /* another new unused entry */
761 int oldlen; /* old unused entry's length */
763 hdr = bp->b_addr;
764 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
765 hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
766 ASSERT(be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG);
767 ASSERT(offset >= (char *)dup - (char *)hdr);
768 ASSERT(offset + len <= (char *)dup + be16_to_cpu(dup->length) - (char *)hdr);
769 ASSERT((char *)dup - (char *)hdr == be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
771 * Look up the entry in the bestfree table.
773 dfp = xfs_dir2_data_freefind(hdr, dup);
774 oldlen = be16_to_cpu(dup->length);
775 ASSERT(dfp || oldlen <= be16_to_cpu(hdr->bestfree[2].length));
777 * Check for alignment with front and back of the entry.
779 matchfront = (char *)dup - (char *)hdr == offset;
780 matchback = (char *)dup + oldlen - (char *)hdr == offset + len;
781 ASSERT(*needscanp == 0);
782 needscan = 0;
784 * If we matched it exactly we just need to get rid of it from
785 * the bestfree table.
787 if (matchfront && matchback) {
788 if (dfp) {
789 needscan = (hdr->bestfree[2].offset != 0);
790 if (!needscan)
791 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
795 * We match the first part of the entry.
796 * Make a new entry with the remaining freespace.
798 else if (matchfront) {
799 newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
800 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
801 newdup->length = cpu_to_be16(oldlen - len);
802 *xfs_dir2_data_unused_tag_p(newdup) =
803 cpu_to_be16((char *)newdup - (char *)hdr);
804 xfs_dir2_data_log_unused(tp, bp, newdup);
806 * If it was in the table, remove it and add the new one.
808 if (dfp) {
809 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
810 dfp = xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
811 ASSERT(dfp != NULL);
812 ASSERT(dfp->length == newdup->length);
813 ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)hdr);
815 * If we got inserted at the last slot,
816 * that means we don't know if there was a better
817 * choice for the last slot, or not. Rescan.
819 needscan = dfp == &hdr->bestfree[2];
823 * We match the last part of the entry.
824 * Trim the allocated space off the tail of the entry.
826 else if (matchback) {
827 newdup = dup;
828 newdup->length = cpu_to_be16(((char *)hdr + offset) - (char *)newdup);
829 *xfs_dir2_data_unused_tag_p(newdup) =
830 cpu_to_be16((char *)newdup - (char *)hdr);
831 xfs_dir2_data_log_unused(tp, bp, newdup);
833 * If it was in the table, remove it and add the new one.
835 if (dfp) {
836 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
837 dfp = xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
838 ASSERT(dfp != NULL);
839 ASSERT(dfp->length == newdup->length);
840 ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)hdr);
842 * If we got inserted at the last slot,
843 * that means we don't know if there was a better
844 * choice for the last slot, or not. Rescan.
846 needscan = dfp == &hdr->bestfree[2];
850 * Poking out the middle of an entry.
851 * Make two new entries.
853 else {
854 newdup = dup;
855 newdup->length = cpu_to_be16(((char *)hdr + offset) - (char *)newdup);
856 *xfs_dir2_data_unused_tag_p(newdup) =
857 cpu_to_be16((char *)newdup - (char *)hdr);
858 xfs_dir2_data_log_unused(tp, bp, newdup);
859 newdup2 = (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
860 newdup2->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
861 newdup2->length = cpu_to_be16(oldlen - len - be16_to_cpu(newdup->length));
862 *xfs_dir2_data_unused_tag_p(newdup2) =
863 cpu_to_be16((char *)newdup2 - (char *)hdr);
864 xfs_dir2_data_log_unused(tp, bp, newdup2);
866 * If the old entry was in the table, we need to scan
867 * if the 3rd entry was valid, since these entries
868 * are smaller than the old one.
869 * If we don't need to scan that means there were 1 or 2
870 * entries in the table, and removing the old and adding
871 * the 2 new will work.
873 if (dfp) {
874 needscan = (hdr->bestfree[2].length != 0);
875 if (!needscan) {
876 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
877 xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
878 xfs_dir2_data_freeinsert(hdr, newdup2,
879 needlogp);
883 *needscanp = needscan;