block: make gendisk hold a reference to its queue
[linux-2.6.git] / fs / xfs / xfs_dir2_data.c
1 /*
2  * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
3  * All Rights Reserved.
4  *
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.
8  *
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.
13  *
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
17  */
18 #include "xfs.h"
19 #include "xfs_fs.h"
20 #include "xfs_types.h"
21 #include "xfs_log.h"
22 #include "xfs_inum.h"
23 #include "xfs_trans.h"
24 #include "xfs_sb.h"
25 #include "xfs_ag.h"
26 #include "xfs_mount.h"
27 #include "xfs_da_btree.h"
28 #include "xfs_bmap_btree.h"
29 #include "xfs_dinode.h"
30 #include "xfs_inode.h"
31 #include "xfs_dir2_format.h"
32 #include "xfs_dir2_priv.h"
33 #include "xfs_error.h"
34
35 STATIC xfs_dir2_data_free_t *
36 xfs_dir2_data_freefind(xfs_dir2_data_hdr_t *hdr, xfs_dir2_data_unused_t *dup);
37
38 #ifdef DEBUG
39 /*
40  * Check the consistency of the data block.
41  * The input can also be a block-format directory.
42  * Pop an assert if we find anything bad.
43  */
44 void
45 xfs_dir2_data_check(
46         xfs_inode_t             *dp,            /* incore inode pointer */
47         xfs_dabuf_t             *bp)            /* data block's buffer */
48 {
49         xfs_dir2_dataptr_t      addr;           /* addr for leaf lookup */
50         xfs_dir2_data_free_t    *bf;            /* bestfree table */
51         xfs_dir2_block_tail_t   *btp=NULL;      /* block tail */
52         int                     count;          /* count of entries found */
53         xfs_dir2_data_hdr_t     *hdr;           /* data block header */
54         xfs_dir2_data_entry_t   *dep;           /* data entry */
55         xfs_dir2_data_free_t    *dfp;           /* bestfree entry */
56         xfs_dir2_data_unused_t  *dup;           /* unused entry */
57         char                    *endp;          /* end of useful data */
58         int                     freeseen;       /* mask of bestfrees seen */
59         xfs_dahash_t            hash;           /* hash of current name */
60         int                     i;              /* leaf index */
61         int                     lastfree;       /* last entry was unused */
62         xfs_dir2_leaf_entry_t   *lep=NULL;      /* block leaf entries */
63         xfs_mount_t             *mp;            /* filesystem mount point */
64         char                    *p;             /* current data position */
65         int                     stale;          /* count of stale leaves */
66         struct xfs_name         name;
67
68         mp = dp->i_mount;
69         hdr = bp->data;
70         bf = hdr->bestfree;
71         p = (char *)(hdr + 1);
72
73         if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
74                 btp = xfs_dir2_block_tail_p(mp, hdr);
75                 lep = xfs_dir2_block_leaf_p(btp);
76                 endp = (char *)lep;
77         } else {
78                 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC));
79                 endp = (char *)hdr + mp->m_dirblksize;
80         }
81
82         count = lastfree = freeseen = 0;
83         /*
84          * Account for zero bestfree entries.
85          */
86         if (!bf[0].length) {
87                 ASSERT(!bf[0].offset);
88                 freeseen |= 1 << 0;
89         }
90         if (!bf[1].length) {
91                 ASSERT(!bf[1].offset);
92                 freeseen |= 1 << 1;
93         }
94         if (!bf[2].length) {
95                 ASSERT(!bf[2].offset);
96                 freeseen |= 1 << 2;
97         }
98         ASSERT(be16_to_cpu(bf[0].length) >= be16_to_cpu(bf[1].length));
99         ASSERT(be16_to_cpu(bf[1].length) >= be16_to_cpu(bf[2].length));
100         /*
101          * Loop over the data/unused entries.
102          */
103         while (p < endp) {
104                 dup = (xfs_dir2_data_unused_t *)p;
105                 /*
106                  * If it's unused, look for the space in the bestfree table.
107                  * If we find it, account for that, else make sure it
108                  * doesn't need to be there.
109                  */
110                 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
111                         ASSERT(lastfree == 0);
112                         ASSERT(be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)) ==
113                                (char *)dup - (char *)hdr);
114                         dfp = xfs_dir2_data_freefind(hdr, dup);
115                         if (dfp) {
116                                 i = (int)(dfp - bf);
117                                 ASSERT((freeseen & (1 << i)) == 0);
118                                 freeseen |= 1 << i;
119                         } else {
120                                 ASSERT(be16_to_cpu(dup->length) <=
121                                        be16_to_cpu(bf[2].length));
122                         }
123                         p += be16_to_cpu(dup->length);
124                         lastfree = 1;
125                         continue;
126                 }
127                 /*
128                  * It's a real entry.  Validate the fields.
129                  * If this is a block directory then make sure it's
130                  * in the leaf section of the block.
131                  * The linear search is crude but this is DEBUG code.
132                  */
133                 dep = (xfs_dir2_data_entry_t *)p;
134                 ASSERT(dep->namelen != 0);
135                 ASSERT(xfs_dir_ino_validate(mp, be64_to_cpu(dep->inumber)) == 0);
136                 ASSERT(be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)) ==
137                        (char *)dep - (char *)hdr);
138                 count++;
139                 lastfree = 0;
140                 if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
141                         addr = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
142                                 (xfs_dir2_data_aoff_t)
143                                 ((char *)dep - (char *)hdr));
144                         name.name = dep->name;
145                         name.len = dep->namelen;
146                         hash = mp->m_dirnameops->hashname(&name);
147                         for (i = 0; i < be32_to_cpu(btp->count); i++) {
148                                 if (be32_to_cpu(lep[i].address) == addr &&
149                                     be32_to_cpu(lep[i].hashval) == hash)
150                                         break;
151                         }
152                         ASSERT(i < be32_to_cpu(btp->count));
153                 }
154                 p += xfs_dir2_data_entsize(dep->namelen);
155         }
156         /*
157          * Need to have seen all the entries and all the bestfree slots.
158          */
159         ASSERT(freeseen == 7);
160         if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
161                 for (i = stale = 0; i < be32_to_cpu(btp->count); i++) {
162                         if (lep[i].address ==
163                             cpu_to_be32(XFS_DIR2_NULL_DATAPTR))
164                                 stale++;
165                         if (i > 0)
166                                 ASSERT(be32_to_cpu(lep[i].hashval) >= be32_to_cpu(lep[i - 1].hashval));
167                 }
168                 ASSERT(count == be32_to_cpu(btp->count) - be32_to_cpu(btp->stale));
169                 ASSERT(stale == be32_to_cpu(btp->stale));
170         }
171 }
172 #endif
173
174 /*
175  * Given a data block and an unused entry from that block,
176  * return the bestfree entry if any that corresponds to it.
177  */
178 STATIC xfs_dir2_data_free_t *
179 xfs_dir2_data_freefind(
180         xfs_dir2_data_hdr_t     *hdr,           /* data block */
181         xfs_dir2_data_unused_t  *dup)           /* data unused entry */
182 {
183         xfs_dir2_data_free_t    *dfp;           /* bestfree entry */
184         xfs_dir2_data_aoff_t    off;            /* offset value needed */
185 #if defined(DEBUG) && defined(__KERNEL__)
186         int                     matched;        /* matched the value */
187         int                     seenzero;       /* saw a 0 bestfree entry */
188 #endif
189
190         off = (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr);
191 #if defined(DEBUG) && defined(__KERNEL__)
192         /*
193          * Validate some consistency in the bestfree table.
194          * Check order, non-overlapping entries, and if we find the
195          * one we're looking for it has to be exact.
196          */
197         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
198                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
199         for (dfp = &hdr->bestfree[0], seenzero = matched = 0;
200              dfp < &hdr->bestfree[XFS_DIR2_DATA_FD_COUNT];
201              dfp++) {
202                 if (!dfp->offset) {
203                         ASSERT(!dfp->length);
204                         seenzero = 1;
205                         continue;
206                 }
207                 ASSERT(seenzero == 0);
208                 if (be16_to_cpu(dfp->offset) == off) {
209                         matched = 1;
210                         ASSERT(dfp->length == dup->length);
211                 } else if (off < be16_to_cpu(dfp->offset))
212                         ASSERT(off + be16_to_cpu(dup->length) <= be16_to_cpu(dfp->offset));
213                 else
214                         ASSERT(be16_to_cpu(dfp->offset) + be16_to_cpu(dfp->length) <= off);
215                 ASSERT(matched || be16_to_cpu(dfp->length) >= be16_to_cpu(dup->length));
216                 if (dfp > &hdr->bestfree[0])
217                         ASSERT(be16_to_cpu(dfp[-1].length) >= be16_to_cpu(dfp[0].length));
218         }
219 #endif
220         /*
221          * If this is smaller than the smallest bestfree entry,
222          * it can't be there since they're sorted.
223          */
224         if (be16_to_cpu(dup->length) <
225             be16_to_cpu(hdr->bestfree[XFS_DIR2_DATA_FD_COUNT - 1].length))
226                 return NULL;
227         /*
228          * Look at the three bestfree entries for our guy.
229          */
230         for (dfp = &hdr->bestfree[0];
231              dfp < &hdr->bestfree[XFS_DIR2_DATA_FD_COUNT];
232              dfp++) {
233                 if (!dfp->offset)
234                         return NULL;
235                 if (be16_to_cpu(dfp->offset) == off)
236                         return dfp;
237         }
238         /*
239          * Didn't find it.  This only happens if there are duplicate lengths.
240          */
241         return NULL;
242 }
243
244 /*
245  * Insert an unused-space entry into the bestfree table.
246  */
247 xfs_dir2_data_free_t *                          /* entry inserted */
248 xfs_dir2_data_freeinsert(
249         xfs_dir2_data_hdr_t     *hdr,           /* data block pointer */
250         xfs_dir2_data_unused_t  *dup,           /* unused space */
251         int                     *loghead)       /* log the data header (out) */
252 {
253         xfs_dir2_data_free_t    *dfp;           /* bestfree table pointer */
254         xfs_dir2_data_free_t    new;            /* new bestfree entry */
255
256 #ifdef __KERNEL__
257         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
258                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
259 #endif
260         dfp = hdr->bestfree;
261         new.length = dup->length;
262         new.offset = cpu_to_be16((char *)dup - (char *)hdr);
263
264         /*
265          * Insert at position 0, 1, or 2; or not at all.
266          */
267         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[0].length)) {
268                 dfp[2] = dfp[1];
269                 dfp[1] = dfp[0];
270                 dfp[0] = new;
271                 *loghead = 1;
272                 return &dfp[0];
273         }
274         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[1].length)) {
275                 dfp[2] = dfp[1];
276                 dfp[1] = new;
277                 *loghead = 1;
278                 return &dfp[1];
279         }
280         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[2].length)) {
281                 dfp[2] = new;
282                 *loghead = 1;
283                 return &dfp[2];
284         }
285         return NULL;
286 }
287
288 /*
289  * Remove a bestfree entry from the table.
290  */
291 STATIC void
292 xfs_dir2_data_freeremove(
293         xfs_dir2_data_hdr_t     *hdr,           /* data block header */
294         xfs_dir2_data_free_t    *dfp,           /* bestfree entry pointer */
295         int                     *loghead)       /* out: log data header */
296 {
297 #ifdef __KERNEL__
298         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
299                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
300 #endif
301         /*
302          * It's the first entry, slide the next 2 up.
303          */
304         if (dfp == &hdr->bestfree[0]) {
305                 hdr->bestfree[0] = hdr->bestfree[1];
306                 hdr->bestfree[1] = hdr->bestfree[2];
307         }
308         /*
309          * It's the second entry, slide the 3rd entry up.
310          */
311         else if (dfp == &hdr->bestfree[1])
312                 hdr->bestfree[1] = hdr->bestfree[2];
313         /*
314          * Must be the last entry.
315          */
316         else
317                 ASSERT(dfp == &hdr->bestfree[2]);
318         /*
319          * Clear the 3rd entry, must be zero now.
320          */
321         hdr->bestfree[2].length = 0;
322         hdr->bestfree[2].offset = 0;
323         *loghead = 1;
324 }
325
326 /*
327  * Given a data block, reconstruct its bestfree map.
328  */
329 void
330 xfs_dir2_data_freescan(
331         xfs_mount_t             *mp,            /* filesystem mount point */
332         xfs_dir2_data_hdr_t     *hdr,           /* data block header */
333         int                     *loghead)       /* out: log data header */
334 {
335         xfs_dir2_block_tail_t   *btp;           /* block tail */
336         xfs_dir2_data_entry_t   *dep;           /* active data entry */
337         xfs_dir2_data_unused_t  *dup;           /* unused data entry */
338         char                    *endp;          /* end of block's data */
339         char                    *p;             /* current entry pointer */
340
341 #ifdef __KERNEL__
342         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
343                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
344 #endif
345         /*
346          * Start by clearing the table.
347          */
348         memset(hdr->bestfree, 0, sizeof(hdr->bestfree));
349         *loghead = 1;
350         /*
351          * Set up pointers.
352          */
353         p = (char *)(hdr + 1);
354         if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
355                 btp = xfs_dir2_block_tail_p(mp, hdr);
356                 endp = (char *)xfs_dir2_block_leaf_p(btp);
357         } else
358                 endp = (char *)hdr + mp->m_dirblksize;
359         /*
360          * Loop over the block's entries.
361          */
362         while (p < endp) {
363                 dup = (xfs_dir2_data_unused_t *)p;
364                 /*
365                  * If it's a free entry, insert it.
366                  */
367                 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
368                         ASSERT((char *)dup - (char *)hdr ==
369                                be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
370                         xfs_dir2_data_freeinsert(hdr, dup, loghead);
371                         p += be16_to_cpu(dup->length);
372                 }
373                 /*
374                  * For active entries, check their tags and skip them.
375                  */
376                 else {
377                         dep = (xfs_dir2_data_entry_t *)p;
378                         ASSERT((char *)dep - (char *)hdr ==
379                                be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)));
380                         p += xfs_dir2_data_entsize(dep->namelen);
381                 }
382         }
383 }
384
385 /*
386  * Initialize a data block at the given block number in the directory.
387  * Give back the buffer for the created block.
388  */
389 int                                             /* error */
390 xfs_dir2_data_init(
391         xfs_da_args_t           *args,          /* directory operation args */
392         xfs_dir2_db_t           blkno,          /* logical dir block number */
393         xfs_dabuf_t             **bpp)          /* output block buffer */
394 {
395         xfs_dabuf_t             *bp;            /* block buffer */
396         xfs_dir2_data_hdr_t     *hdr;           /* data block header */
397         xfs_inode_t             *dp;            /* incore directory inode */
398         xfs_dir2_data_unused_t  *dup;           /* unused entry pointer */
399         int                     error;          /* error return value */
400         int                     i;              /* bestfree index */
401         xfs_mount_t             *mp;            /* filesystem mount point */
402         xfs_trans_t             *tp;            /* transaction pointer */
403         int                     t;              /* temp */
404
405         dp = args->dp;
406         mp = dp->i_mount;
407         tp = args->trans;
408         /*
409          * Get the buffer set up for the block.
410          */
411         error = xfs_da_get_buf(tp, dp, xfs_dir2_db_to_da(mp, blkno), -1, &bp,
412                 XFS_DATA_FORK);
413         if (error) {
414                 return error;
415         }
416         ASSERT(bp != NULL);
417
418         /*
419          * Initialize the header.
420          */
421         hdr = bp->data;
422         hdr->magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);
423         hdr->bestfree[0].offset = cpu_to_be16(sizeof(*hdr));
424         for (i = 1; i < XFS_DIR2_DATA_FD_COUNT; i++) {
425                 hdr->bestfree[i].length = 0;
426                 hdr->bestfree[i].offset = 0;
427         }
428
429         /*
430          * Set up an unused entry for the block's body.
431          */
432         dup = (xfs_dir2_data_unused_t *)(hdr + 1);
433         dup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
434
435         t = mp->m_dirblksize - (uint)sizeof(*hdr);
436         hdr->bestfree[0].length = cpu_to_be16(t);
437         dup->length = cpu_to_be16(t);
438         *xfs_dir2_data_unused_tag_p(dup) = cpu_to_be16((char *)dup - (char *)hdr);
439         /*
440          * Log it and return it.
441          */
442         xfs_dir2_data_log_header(tp, bp);
443         xfs_dir2_data_log_unused(tp, bp, dup);
444         *bpp = bp;
445         return 0;
446 }
447
448 /*
449  * Log an active data entry from the block.
450  */
451 void
452 xfs_dir2_data_log_entry(
453         xfs_trans_t             *tp,            /* transaction pointer */
454         xfs_dabuf_t             *bp,            /* block buffer */
455         xfs_dir2_data_entry_t   *dep)           /* data entry pointer */
456 {
457         xfs_dir2_data_hdr_t     *hdr = bp->data;
458
459         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
460                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
461
462         xfs_da_log_buf(tp, bp, (uint)((char *)dep - (char *)hdr),
463                 (uint)((char *)(xfs_dir2_data_entry_tag_p(dep) + 1) -
464                        (char *)hdr - 1));
465 }
466
467 /*
468  * Log a data block header.
469  */
470 void
471 xfs_dir2_data_log_header(
472         xfs_trans_t             *tp,            /* transaction pointer */
473         xfs_dabuf_t             *bp)            /* block buffer */
474 {
475         xfs_dir2_data_hdr_t     *hdr = bp->data;
476
477         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
478                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
479
480         xfs_da_log_buf(tp, bp, 0, sizeof(*hdr) - 1);
481 }
482
483 /*
484  * Log a data unused entry.
485  */
486 void
487 xfs_dir2_data_log_unused(
488         xfs_trans_t             *tp,            /* transaction pointer */
489         xfs_dabuf_t             *bp,            /* block buffer */
490         xfs_dir2_data_unused_t  *dup)           /* data unused pointer */
491 {
492         xfs_dir2_data_hdr_t     *hdr = bp->data;
493
494         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
495                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
496
497         /*
498          * Log the first part of the unused entry.
499          */
500         xfs_da_log_buf(tp, bp, (uint)((char *)dup - (char *)hdr),
501                 (uint)((char *)&dup->length + sizeof(dup->length) -
502                        1 - (char *)hdr));
503         /*
504          * Log the end (tag) of the unused entry.
505          */
506         xfs_da_log_buf(tp, bp,
507                 (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)hdr),
508                 (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)hdr +
509                        sizeof(xfs_dir2_data_off_t) - 1));
510 }
511
512 /*
513  * Make a byte range in the data block unused.
514  * Its current contents are unimportant.
515  */
516 void
517 xfs_dir2_data_make_free(
518         xfs_trans_t             *tp,            /* transaction pointer */
519         xfs_dabuf_t             *bp,            /* block buffer */
520         xfs_dir2_data_aoff_t    offset,         /* starting byte offset */
521         xfs_dir2_data_aoff_t    len,            /* length in bytes */
522         int                     *needlogp,      /* out: log header */
523         int                     *needscanp)     /* out: regen bestfree */
524 {
525         xfs_dir2_data_hdr_t     *hdr;           /* data block pointer */
526         xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
527         char                    *endptr;        /* end of data area */
528         xfs_mount_t             *mp;            /* filesystem mount point */
529         int                     needscan;       /* need to regen bestfree */
530         xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
531         xfs_dir2_data_unused_t  *postdup;       /* unused entry after us */
532         xfs_dir2_data_unused_t  *prevdup;       /* unused entry before us */
533
534         mp = tp->t_mountp;
535         hdr = bp->data;
536
537         /*
538          * Figure out where the end of the data area is.
539          */
540         if (hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC))
541                 endptr = (char *)hdr + mp->m_dirblksize;
542         else {
543                 xfs_dir2_block_tail_t   *btp;   /* block tail */
544
545                 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
546                 btp = xfs_dir2_block_tail_p(mp, hdr);
547                 endptr = (char *)xfs_dir2_block_leaf_p(btp);
548         }
549         /*
550          * If this isn't the start of the block, then back up to
551          * the previous entry and see if it's free.
552          */
553         if (offset > sizeof(*hdr)) {
554                 __be16                  *tagp;  /* tag just before us */
555
556                 tagp = (__be16 *)((char *)hdr + offset) - 1;
557                 prevdup = (xfs_dir2_data_unused_t *)((char *)hdr + be16_to_cpu(*tagp));
558                 if (be16_to_cpu(prevdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
559                         prevdup = NULL;
560         } else
561                 prevdup = NULL;
562         /*
563          * If this isn't the end of the block, see if the entry after
564          * us is free.
565          */
566         if ((char *)hdr + offset + len < endptr) {
567                 postdup =
568                         (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
569                 if (be16_to_cpu(postdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
570                         postdup = NULL;
571         } else
572                 postdup = NULL;
573         ASSERT(*needscanp == 0);
574         needscan = 0;
575         /*
576          * Previous and following entries are both free,
577          * merge everything into a single free entry.
578          */
579         if (prevdup && postdup) {
580                 xfs_dir2_data_free_t    *dfp2;  /* another bestfree pointer */
581
582                 /*
583                  * See if prevdup and/or postdup are in bestfree table.
584                  */
585                 dfp = xfs_dir2_data_freefind(hdr, prevdup);
586                 dfp2 = xfs_dir2_data_freefind(hdr, postdup);
587                 /*
588                  * We need a rescan unless there are exactly 2 free entries
589                  * namely our two.  Then we know what's happening, otherwise
590                  * since the third bestfree is there, there might be more
591                  * entries.
592                  */
593                 needscan = (hdr->bestfree[2].length != 0);
594                 /*
595                  * Fix up the new big freespace.
596                  */
597                 be16_add_cpu(&prevdup->length, len + be16_to_cpu(postdup->length));
598                 *xfs_dir2_data_unused_tag_p(prevdup) =
599                         cpu_to_be16((char *)prevdup - (char *)hdr);
600                 xfs_dir2_data_log_unused(tp, bp, prevdup);
601                 if (!needscan) {
602                         /*
603                          * Has to be the case that entries 0 and 1 are
604                          * dfp and dfp2 (don't know which is which), and
605                          * entry 2 is empty.
606                          * Remove entry 1 first then entry 0.
607                          */
608                         ASSERT(dfp && dfp2);
609                         if (dfp == &hdr->bestfree[1]) {
610                                 dfp = &hdr->bestfree[0];
611                                 ASSERT(dfp2 == dfp);
612                                 dfp2 = &hdr->bestfree[1];
613                         }
614                         xfs_dir2_data_freeremove(hdr, dfp2, needlogp);
615                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
616                         /*
617                          * Now insert the new entry.
618                          */
619                         dfp = xfs_dir2_data_freeinsert(hdr, prevdup, needlogp);
620                         ASSERT(dfp == &hdr->bestfree[0]);
621                         ASSERT(dfp->length == prevdup->length);
622                         ASSERT(!dfp[1].length);
623                         ASSERT(!dfp[2].length);
624                 }
625         }
626         /*
627          * The entry before us is free, merge with it.
628          */
629         else if (prevdup) {
630                 dfp = xfs_dir2_data_freefind(hdr, prevdup);
631                 be16_add_cpu(&prevdup->length, len);
632                 *xfs_dir2_data_unused_tag_p(prevdup) =
633                         cpu_to_be16((char *)prevdup - (char *)hdr);
634                 xfs_dir2_data_log_unused(tp, bp, prevdup);
635                 /*
636                  * If the previous entry was in the table, the new entry
637                  * is longer, so it will be in the table too.  Remove
638                  * the old one and add the new one.
639                  */
640                 if (dfp) {
641                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
642                         xfs_dir2_data_freeinsert(hdr, prevdup, needlogp);
643                 }
644                 /*
645                  * Otherwise we need a scan if the new entry is big enough.
646                  */
647                 else {
648                         needscan = be16_to_cpu(prevdup->length) >
649                                    be16_to_cpu(hdr->bestfree[2].length);
650                 }
651         }
652         /*
653          * The following entry is free, merge with it.
654          */
655         else if (postdup) {
656                 dfp = xfs_dir2_data_freefind(hdr, postdup);
657                 newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset);
658                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
659                 newdup->length = cpu_to_be16(len + be16_to_cpu(postdup->length));
660                 *xfs_dir2_data_unused_tag_p(newdup) =
661                         cpu_to_be16((char *)newdup - (char *)hdr);
662                 xfs_dir2_data_log_unused(tp, bp, newdup);
663                 /*
664                  * If the following entry was in the table, the new entry
665                  * is longer, so it will be in the table too.  Remove
666                  * the old one and add the new one.
667                  */
668                 if (dfp) {
669                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
670                         xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
671                 }
672                 /*
673                  * Otherwise we need a scan if the new entry is big enough.
674                  */
675                 else {
676                         needscan = be16_to_cpu(newdup->length) >
677                                    be16_to_cpu(hdr->bestfree[2].length);
678                 }
679         }
680         /*
681          * Neither neighbor is free.  Make a new entry.
682          */
683         else {
684                 newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset);
685                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
686                 newdup->length = cpu_to_be16(len);
687                 *xfs_dir2_data_unused_tag_p(newdup) =
688                         cpu_to_be16((char *)newdup - (char *)hdr);
689                 xfs_dir2_data_log_unused(tp, bp, newdup);
690                 xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
691         }
692         *needscanp = needscan;
693 }
694
695 /*
696  * Take a byte range out of an existing unused space and make it un-free.
697  */
698 void
699 xfs_dir2_data_use_free(
700         xfs_trans_t             *tp,            /* transaction pointer */
701         xfs_dabuf_t             *bp,            /* data block buffer */
702         xfs_dir2_data_unused_t  *dup,           /* unused entry */
703         xfs_dir2_data_aoff_t    offset,         /* starting offset to use */
704         xfs_dir2_data_aoff_t    len,            /* length to use */
705         int                     *needlogp,      /* out: need to log header */
706         int                     *needscanp)     /* out: need regen bestfree */
707 {
708         xfs_dir2_data_hdr_t     *hdr;           /* data block header */
709         xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
710         int                     matchback;      /* matches end of freespace */
711         int                     matchfront;     /* matches start of freespace */
712         int                     needscan;       /* need to regen bestfree */
713         xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
714         xfs_dir2_data_unused_t  *newdup2;       /* another new unused entry */
715         int                     oldlen;         /* old unused entry's length */
716
717         hdr = bp->data;
718         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
719                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
720         ASSERT(be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG);
721         ASSERT(offset >= (char *)dup - (char *)hdr);
722         ASSERT(offset + len <= (char *)dup + be16_to_cpu(dup->length) - (char *)hdr);
723         ASSERT((char *)dup - (char *)hdr == be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
724         /*
725          * Look up the entry in the bestfree table.
726          */
727         dfp = xfs_dir2_data_freefind(hdr, dup);
728         oldlen = be16_to_cpu(dup->length);
729         ASSERT(dfp || oldlen <= be16_to_cpu(hdr->bestfree[2].length));
730         /*
731          * Check for alignment with front and back of the entry.
732          */
733         matchfront = (char *)dup - (char *)hdr == offset;
734         matchback = (char *)dup + oldlen - (char *)hdr == offset + len;
735         ASSERT(*needscanp == 0);
736         needscan = 0;
737         /*
738          * If we matched it exactly we just need to get rid of it from
739          * the bestfree table.
740          */
741         if (matchfront && matchback) {
742                 if (dfp) {
743                         needscan = (hdr->bestfree[2].offset != 0);
744                         if (!needscan)
745                                 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
746                 }
747         }
748         /*
749          * We match the first part of the entry.
750          * Make a new entry with the remaining freespace.
751          */
752         else if (matchfront) {
753                 newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
754                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
755                 newdup->length = cpu_to_be16(oldlen - len);
756                 *xfs_dir2_data_unused_tag_p(newdup) =
757                         cpu_to_be16((char *)newdup - (char *)hdr);
758                 xfs_dir2_data_log_unused(tp, bp, newdup);
759                 /*
760                  * If it was in the table, remove it and add the new one.
761                  */
762                 if (dfp) {
763                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
764                         dfp = xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
765                         ASSERT(dfp != NULL);
766                         ASSERT(dfp->length == newdup->length);
767                         ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)hdr);
768                         /*
769                          * If we got inserted at the last slot,
770                          * that means we don't know if there was a better
771                          * choice for the last slot, or not.  Rescan.
772                          */
773                         needscan = dfp == &hdr->bestfree[2];
774                 }
775         }
776         /*
777          * We match the last part of the entry.
778          * Trim the allocated space off the tail of the entry.
779          */
780         else if (matchback) {
781                 newdup = dup;
782                 newdup->length = cpu_to_be16(((char *)hdr + offset) - (char *)newdup);
783                 *xfs_dir2_data_unused_tag_p(newdup) =
784                         cpu_to_be16((char *)newdup - (char *)hdr);
785                 xfs_dir2_data_log_unused(tp, bp, newdup);
786                 /*
787                  * If it was in the table, remove it and add the new one.
788                  */
789                 if (dfp) {
790                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
791                         dfp = xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
792                         ASSERT(dfp != NULL);
793                         ASSERT(dfp->length == newdup->length);
794                         ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)hdr);
795                         /*
796                          * If we got inserted at the last slot,
797                          * that means we don't know if there was a better
798                          * choice for the last slot, or not.  Rescan.
799                          */
800                         needscan = dfp == &hdr->bestfree[2];
801                 }
802         }
803         /*
804          * Poking out the middle of an entry.
805          * Make two new entries.
806          */
807         else {
808                 newdup = dup;
809                 newdup->length = cpu_to_be16(((char *)hdr + offset) - (char *)newdup);
810                 *xfs_dir2_data_unused_tag_p(newdup) =
811                         cpu_to_be16((char *)newdup - (char *)hdr);
812                 xfs_dir2_data_log_unused(tp, bp, newdup);
813                 newdup2 = (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
814                 newdup2->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
815                 newdup2->length = cpu_to_be16(oldlen - len - be16_to_cpu(newdup->length));
816                 *xfs_dir2_data_unused_tag_p(newdup2) =
817                         cpu_to_be16((char *)newdup2 - (char *)hdr);
818                 xfs_dir2_data_log_unused(tp, bp, newdup2);
819                 /*
820                  * If the old entry was in the table, we need to scan
821                  * if the 3rd entry was valid, since these entries
822                  * are smaller than the old one.
823                  * If we don't need to scan that means there were 1 or 2
824                  * entries in the table, and removing the old and adding
825                  * the 2 new will work.
826                  */
827                 if (dfp) {
828                         needscan = (hdr->bestfree[2].length != 0);
829                         if (!needscan) {
830                                 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
831                                 xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
832                                 xfs_dir2_data_freeinsert(hdr, newdup2,
833                                                          needlogp);
834                         }
835                 }
836         }
837         *needscanp = needscan;
838 }