[PATCH] VFS: Permit filesystem to override root dentry on mount
[linux-2.6.git] / fs / qnx4 / inode.c
1 /*
2  * QNX4 file system, Linux implementation.
3  *
4  * Version : 0.2.1
5  *
6  * Using parts of the xiafs filesystem.
7  *
8  * History :
9  *
10  * 01-06-1998 by Richard Frowijn : first release.
11  * 20-06-1998 by Frank Denis : Linux 2.1.99+ support, boot signature, misc.
12  * 30-06-1998 by Frank Denis : first step to write inodes.
13  */
14
15 #include <linux/config.h>
16 #include <linux/module.h>
17 #include <linux/types.h>
18 #include <linux/string.h>
19 #include <linux/errno.h>
20 #include <linux/slab.h>
21 #include <linux/fs.h>
22 #include <linux/qnx4_fs.h>
23 #include <linux/init.h>
24 #include <linux/highuid.h>
25 #include <linux/smp_lock.h>
26 #include <linux/pagemap.h>
27 #include <linux/buffer_head.h>
28 #include <linux/vfs.h>
29 #include <asm/uaccess.h>
30
31 #define QNX4_VERSION  4
32 #define QNX4_BMNAME   ".bitmap"
33
34 static struct super_operations qnx4_sops;
35
36 #ifdef CONFIG_QNX4FS_RW
37
38 int qnx4_sync_inode(struct inode *inode)
39 {
40         int err = 0;
41 # if 0
42         struct buffer_head *bh;
43
44         bh = qnx4_update_inode(inode);
45         if (bh && buffer_dirty(bh))
46         {
47                 sync_dirty_buffer(bh);
48                 if (buffer_req(bh) && !buffer_uptodate(bh))
49                 {
50                         printk ("IO error syncing qnx4 inode [%s:%08lx]\n",
51                                 inode->i_sb->s_id, inode->i_ino);
52                         err = -1;
53                 }
54                 brelse (bh);
55         } else if (!bh) {
56                 err = -1;
57         }
58 # endif
59
60         return err;
61 }
62
63 static void qnx4_delete_inode(struct inode *inode)
64 {
65         QNX4DEBUG(("qnx4: deleting inode [%lu]\n", (unsigned long) inode->i_ino));
66         truncate_inode_pages(&inode->i_data, 0);
67         inode->i_size = 0;
68         qnx4_truncate(inode);
69         lock_kernel();
70         qnx4_free_inode(inode);
71         unlock_kernel();
72 }
73
74 static void qnx4_write_super(struct super_block *sb)
75 {
76         lock_kernel();
77         QNX4DEBUG(("qnx4: write_super\n"));
78         sb->s_dirt = 0;
79         unlock_kernel();
80 }
81
82 static int qnx4_write_inode(struct inode *inode, int unused)
83 {
84         struct qnx4_inode_entry *raw_inode;
85         int block, ino;
86         struct buffer_head *bh;
87         ino = inode->i_ino;
88
89         QNX4DEBUG(("qnx4: write inode 1.\n"));
90         if (inode->i_nlink == 0) {
91                 return 0;
92         }
93         if (!ino) {
94                 printk("qnx4: bad inode number on dev %s: %d is out of range\n",
95                        inode->i_sb->s_id, ino);
96                 return -EIO;
97         }
98         QNX4DEBUG(("qnx4: write inode 2.\n"));
99         block = ino / QNX4_INODES_PER_BLOCK;
100         lock_kernel();
101         if (!(bh = sb_bread(inode->i_sb, block))) {
102                 printk("qnx4: major problem: unable to read inode from dev "
103                        "%s\n", inode->i_sb->s_id);
104                 unlock_kernel();
105                 return -EIO;
106         }
107         raw_inode = ((struct qnx4_inode_entry *) bh->b_data) +
108             (ino % QNX4_INODES_PER_BLOCK);
109         raw_inode->di_mode  = cpu_to_le16(inode->i_mode);
110         raw_inode->di_uid   = cpu_to_le16(fs_high2lowuid(inode->i_uid));
111         raw_inode->di_gid   = cpu_to_le16(fs_high2lowgid(inode->i_gid));
112         raw_inode->di_nlink = cpu_to_le16(inode->i_nlink);
113         raw_inode->di_size  = cpu_to_le32(inode->i_size);
114         raw_inode->di_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
115         raw_inode->di_atime = cpu_to_le32(inode->i_atime.tv_sec);
116         raw_inode->di_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
117         raw_inode->di_first_xtnt.xtnt_size = cpu_to_le32(inode->i_blocks);
118         mark_buffer_dirty(bh);
119         brelse(bh);
120         unlock_kernel();
121         return 0;
122 }
123
124 #endif
125
126 static void qnx4_put_super(struct super_block *sb);
127 static struct inode *qnx4_alloc_inode(struct super_block *sb);
128 static void qnx4_destroy_inode(struct inode *inode);
129 static void qnx4_read_inode(struct inode *);
130 static int qnx4_remount(struct super_block *sb, int *flags, char *data);
131 static int qnx4_statfs(struct super_block *, struct kstatfs *);
132
133 static struct super_operations qnx4_sops =
134 {
135         .alloc_inode    = qnx4_alloc_inode,
136         .destroy_inode  = qnx4_destroy_inode,
137         .read_inode     = qnx4_read_inode,
138         .put_super      = qnx4_put_super,
139         .statfs         = qnx4_statfs,
140         .remount_fs     = qnx4_remount,
141 #ifdef CONFIG_QNX4FS_RW
142         .write_inode    = qnx4_write_inode,
143         .delete_inode   = qnx4_delete_inode,
144         .write_super    = qnx4_write_super,
145 #endif
146 };
147
148 static int qnx4_remount(struct super_block *sb, int *flags, char *data)
149 {
150         struct qnx4_sb_info *qs;
151
152         qs = qnx4_sb(sb);
153         qs->Version = QNX4_VERSION;
154 #ifndef CONFIG_QNX4FS_RW
155         *flags |= MS_RDONLY;
156 #endif
157         if (*flags & MS_RDONLY) {
158                 return 0;
159         }
160
161         mark_buffer_dirty(qs->sb_buf);
162
163         return 0;
164 }
165
166 static struct buffer_head *qnx4_getblk(struct inode *inode, int nr,
167                                        int create)
168 {
169         struct buffer_head *result = NULL;
170
171         if ( nr >= 0 )
172                 nr = qnx4_block_map( inode, nr );
173         if (nr) {
174                 result = sb_getblk(inode->i_sb, nr);
175                 return result;
176         }
177         if (!create) {
178                 return NULL;
179         }
180 #if 0
181         tmp = qnx4_new_block(inode->i_sb);
182         if (!tmp) {
183                 return NULL;
184         }
185         result = sb_getblk(inode->i_sb, tmp);
186         if (tst) {
187                 qnx4_free_block(inode->i_sb, tmp);
188                 brelse(result);
189                 goto repeat;
190         }
191         tst = tmp;
192 #endif
193         inode->i_ctime = CURRENT_TIME_SEC;
194         mark_inode_dirty(inode);
195         return result;
196 }
197
198 struct buffer_head *qnx4_bread(struct inode *inode, int block, int create)
199 {
200         struct buffer_head *bh;
201
202         bh = qnx4_getblk(inode, block, create);
203         if (!bh || buffer_uptodate(bh)) {
204                 return bh;
205         }
206         ll_rw_block(READ, 1, &bh);
207         wait_on_buffer(bh);
208         if (buffer_uptodate(bh)) {
209                 return bh;
210         }
211         brelse(bh);
212
213         return NULL;
214 }
215
216 static int qnx4_get_block( struct inode *inode, sector_t iblock, struct buffer_head *bh, int create )
217 {
218         unsigned long phys;
219
220         QNX4DEBUG(("qnx4: qnx4_get_block inode=[%ld] iblock=[%ld]\n",inode->i_ino,iblock));
221
222         phys = qnx4_block_map( inode, iblock );
223         if ( phys ) {
224                 // logical block is before EOF
225                 map_bh(bh, inode->i_sb, phys);
226         } else if ( create ) {
227                 // to be done.
228         }
229         return 0;
230 }
231
232 unsigned long qnx4_block_map( struct inode *inode, long iblock )
233 {
234         int ix;
235         long offset, i_xblk;
236         unsigned long block = 0;
237         struct buffer_head *bh = NULL;
238         struct qnx4_xblk *xblk = NULL;
239         struct qnx4_inode_entry *qnx4_inode = qnx4_raw_inode(inode);
240         u16 nxtnt = le16_to_cpu(qnx4_inode->di_num_xtnts);
241
242         if ( iblock < le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_size) ) {
243                 // iblock is in the first extent. This is easy.
244                 block = le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_blk) + iblock - 1;
245         } else {
246                 // iblock is beyond first extent. We have to follow the extent chain.
247                 i_xblk = le32_to_cpu(qnx4_inode->di_xblk);
248                 offset = iblock - le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_size);
249                 ix = 0;
250                 while ( --nxtnt > 0 ) {
251                         if ( ix == 0 ) {
252                                 // read next xtnt block.
253                                 bh = sb_bread(inode->i_sb, i_xblk - 1);
254                                 if ( !bh ) {
255                                         QNX4DEBUG(("qnx4: I/O error reading xtnt block [%ld])\n", i_xblk - 1));
256                                         return -EIO;
257                                 }
258                                 xblk = (struct qnx4_xblk*)bh->b_data;
259                                 if ( memcmp( xblk->xblk_signature, "IamXblk", 7 ) ) {
260                                         QNX4DEBUG(("qnx4: block at %ld is not a valid xtnt\n", qnx4_inode->i_xblk));
261                                         return -EIO;
262                                 }
263                         }
264                         if ( offset < le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_size) ) {
265                                 // got it!
266                                 block = le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_blk) + offset - 1;
267                                 break;
268                         }
269                         offset -= le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_size);
270                         if ( ++ix >= xblk->xblk_num_xtnts ) {
271                                 i_xblk = le32_to_cpu(xblk->xblk_next_xblk);
272                                 ix = 0;
273                                 brelse( bh );
274                                 bh = NULL;
275                         }
276                 }
277                 if ( bh )
278                         brelse( bh );
279         }
280
281         QNX4DEBUG(("qnx4: mapping block %ld of inode %ld = %ld\n",iblock,inode->i_ino,block));
282         return block;
283 }
284
285 static int qnx4_statfs(struct super_block *sb, struct kstatfs *buf)
286 {
287         lock_kernel();
288
289         buf->f_type    = sb->s_magic;
290         buf->f_bsize   = sb->s_blocksize;
291         buf->f_blocks  = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size) * 8;
292         buf->f_bfree   = qnx4_count_free_blocks(sb);
293         buf->f_bavail  = buf->f_bfree;
294         buf->f_namelen = QNX4_NAME_MAX;
295
296         unlock_kernel();
297
298         return 0;
299 }
300
301 /*
302  * Check the root directory of the filesystem to make sure
303  * it really _is_ a qnx4 filesystem, and to check the size
304  * of the directory entry.
305  */
306 static const char *qnx4_checkroot(struct super_block *sb)
307 {
308         struct buffer_head *bh;
309         struct qnx4_inode_entry *rootdir;
310         int rd, rl;
311         int i, j;
312         int found = 0;
313
314         if (*(qnx4_sb(sb)->sb->RootDir.di_fname) != '/') {
315                 return "no qnx4 filesystem (no root dir).";
316         } else {
317                 QNX4DEBUG(("QNX4 filesystem found on dev %s.\n", sb->s_id));
318                 rd = le32_to_cpu(qnx4_sb(sb)->sb->RootDir.di_first_xtnt.xtnt_blk) - 1;
319                 rl = le32_to_cpu(qnx4_sb(sb)->sb->RootDir.di_first_xtnt.xtnt_size);
320                 for (j = 0; j < rl; j++) {
321                         bh = sb_bread(sb, rd + j);      /* root dir, first block */
322                         if (bh == NULL) {
323                                 return "unable to read root entry.";
324                         }
325                         for (i = 0; i < QNX4_INODES_PER_BLOCK; i++) {
326                                 rootdir = (struct qnx4_inode_entry *) (bh->b_data + i * QNX4_DIR_ENTRY_SIZE);
327                                 if (rootdir->di_fname != NULL) {
328                                         QNX4DEBUG(("Rootdir entry found : [%s]\n", rootdir->di_fname));
329                                         if (!strncmp(rootdir->di_fname, QNX4_BMNAME, sizeof QNX4_BMNAME)) {
330                                                 found = 1;
331                                                 qnx4_sb(sb)->BitMap = kmalloc( sizeof( struct qnx4_inode_entry ), GFP_KERNEL );
332                                                 if (!qnx4_sb(sb)->BitMap) {
333                                                         brelse (bh);
334                                                         return "not enough memory for bitmap inode";
335                                                 }
336                                                 memcpy( qnx4_sb(sb)->BitMap, rootdir, sizeof( struct qnx4_inode_entry ) );      /* keep bitmap inode known */
337                                                 break;
338                                         }
339                                 }
340                         }
341                         brelse(bh);
342                         if (found != 0) {
343                                 break;
344                         }
345                 }
346                 if (found == 0) {
347                         return "bitmap file not found.";
348                 }
349         }
350         return NULL;
351 }
352
353 static int qnx4_fill_super(struct super_block *s, void *data, int silent)
354 {
355         struct buffer_head *bh;
356         struct inode *root;
357         const char *errmsg;
358         struct qnx4_sb_info *qs;
359
360         qs = kmalloc(sizeof(struct qnx4_sb_info), GFP_KERNEL);
361         if (!qs)
362                 return -ENOMEM;
363         s->s_fs_info = qs;
364         memset(qs, 0, sizeof(struct qnx4_sb_info));
365
366         sb_set_blocksize(s, QNX4_BLOCK_SIZE);
367
368         /* Check the superblock signature. Since the qnx4 code is
369            dangerous, we should leave as quickly as possible
370            if we don't belong here... */
371         bh = sb_bread(s, 1);
372         if (!bh) {
373                 printk("qnx4: unable to read the superblock\n");
374                 goto outnobh;
375         }
376         if ( le32_to_cpup((__le32*) bh->b_data) != QNX4_SUPER_MAGIC ) {
377                 if (!silent)
378                         printk("qnx4: wrong fsid in superblock.\n");
379                 goto out;
380         }
381         s->s_op = &qnx4_sops;
382         s->s_magic = QNX4_SUPER_MAGIC;
383 #ifndef CONFIG_QNX4FS_RW
384         s->s_flags |= MS_RDONLY;        /* Yup, read-only yet */
385 #endif
386         qnx4_sb(s)->sb_buf = bh;
387         qnx4_sb(s)->sb = (struct qnx4_super_block *) bh->b_data;
388
389
390         /* check before allocating dentries, inodes, .. */
391         errmsg = qnx4_checkroot(s);
392         if (errmsg != NULL) {
393                 if (!silent)
394                         printk("qnx4: %s\n", errmsg);
395                 goto out;
396         }
397
398         /* does root not have inode number QNX4_ROOT_INO ?? */
399         root = iget(s, QNX4_ROOT_INO * QNX4_INODES_PER_BLOCK);
400         if (!root) {
401                 printk("qnx4: get inode failed\n");
402                 goto out;
403         }
404
405         s->s_root = d_alloc_root(root);
406         if (s->s_root == NULL)
407                 goto outi;
408
409         brelse(bh);
410
411         return 0;
412
413       outi:
414         iput(root);
415       out:
416         brelse(bh);
417       outnobh:
418         kfree(qs);
419         s->s_fs_info = NULL;
420         return -EINVAL;
421 }
422
423 static void qnx4_put_super(struct super_block *sb)
424 {
425         struct qnx4_sb_info *qs = qnx4_sb(sb);
426         kfree( qs->BitMap );
427         kfree( qs );
428         sb->s_fs_info = NULL;
429         return;
430 }
431
432 static int qnx4_writepage(struct page *page, struct writeback_control *wbc)
433 {
434         return block_write_full_page(page,qnx4_get_block, wbc);
435 }
436 static int qnx4_readpage(struct file *file, struct page *page)
437 {
438         return block_read_full_page(page,qnx4_get_block);
439 }
440 static int qnx4_prepare_write(struct file *file, struct page *page,
441                               unsigned from, unsigned to)
442 {
443         struct qnx4_inode_info *qnx4_inode = qnx4_i(page->mapping->host);
444         return cont_prepare_write(page, from, to, qnx4_get_block,
445                                   &qnx4_inode->mmu_private);
446 }
447 static sector_t qnx4_bmap(struct address_space *mapping, sector_t block)
448 {
449         return generic_block_bmap(mapping,block,qnx4_get_block);
450 }
451 static struct address_space_operations qnx4_aops = {
452         .readpage       = qnx4_readpage,
453         .writepage      = qnx4_writepage,
454         .sync_page      = block_sync_page,
455         .prepare_write  = qnx4_prepare_write,
456         .commit_write   = generic_commit_write,
457         .bmap           = qnx4_bmap
458 };
459
460 static void qnx4_read_inode(struct inode *inode)
461 {
462         struct buffer_head *bh;
463         struct qnx4_inode_entry *raw_inode;
464         int block, ino;
465         struct super_block *sb = inode->i_sb;
466         struct qnx4_inode_entry *qnx4_inode = qnx4_raw_inode(inode);
467
468         ino = inode->i_ino;
469         inode->i_mode = 0;
470
471         QNX4DEBUG(("Reading inode : [%d]\n", ino));
472         if (!ino) {
473                 printk("qnx4: bad inode number on dev %s: %d is out of range\n",
474                        sb->s_id, ino);
475                 return;
476         }
477         block = ino / QNX4_INODES_PER_BLOCK;
478
479         if (!(bh = sb_bread(sb, block))) {
480                 printk("qnx4: major problem: unable to read inode from dev "
481                        "%s\n", sb->s_id);
482                 return;
483         }
484         raw_inode = ((struct qnx4_inode_entry *) bh->b_data) +
485             (ino % QNX4_INODES_PER_BLOCK);
486
487         inode->i_mode    = le16_to_cpu(raw_inode->di_mode);
488         inode->i_uid     = (uid_t)le16_to_cpu(raw_inode->di_uid);
489         inode->i_gid     = (gid_t)le16_to_cpu(raw_inode->di_gid);
490         inode->i_nlink   = le16_to_cpu(raw_inode->di_nlink);
491         inode->i_size    = le32_to_cpu(raw_inode->di_size);
492         inode->i_mtime.tv_sec   = le32_to_cpu(raw_inode->di_mtime);
493         inode->i_mtime.tv_nsec = 0;
494         inode->i_atime.tv_sec   = le32_to_cpu(raw_inode->di_atime);
495         inode->i_atime.tv_nsec = 0;
496         inode->i_ctime.tv_sec   = le32_to_cpu(raw_inode->di_ctime);
497         inode->i_ctime.tv_nsec = 0;
498         inode->i_blocks  = le32_to_cpu(raw_inode->di_first_xtnt.xtnt_size);
499         inode->i_blksize = QNX4_DIR_ENTRY_SIZE;
500
501         memcpy(qnx4_inode, raw_inode, QNX4_DIR_ENTRY_SIZE);
502         if (S_ISREG(inode->i_mode)) {
503                 inode->i_op = &qnx4_file_inode_operations;
504                 inode->i_fop = &qnx4_file_operations;
505                 inode->i_mapping->a_ops = &qnx4_aops;
506                 qnx4_i(inode)->mmu_private = inode->i_size;
507         } else if (S_ISDIR(inode->i_mode)) {
508                 inode->i_op = &qnx4_dir_inode_operations;
509                 inode->i_fop = &qnx4_dir_operations;
510         } else if (S_ISLNK(inode->i_mode)) {
511                 inode->i_op = &page_symlink_inode_operations;
512                 inode->i_mapping->a_ops = &qnx4_aops;
513                 qnx4_i(inode)->mmu_private = inode->i_size;
514         } else
515                 printk("qnx4: bad inode %d on dev %s\n",ino,sb->s_id);
516         brelse(bh);
517 }
518
519 static kmem_cache_t *qnx4_inode_cachep;
520
521 static struct inode *qnx4_alloc_inode(struct super_block *sb)
522 {
523         struct qnx4_inode_info *ei;
524         ei = kmem_cache_alloc(qnx4_inode_cachep, SLAB_KERNEL);
525         if (!ei)
526                 return NULL;
527         return &ei->vfs_inode;
528 }
529
530 static void qnx4_destroy_inode(struct inode *inode)
531 {
532         kmem_cache_free(qnx4_inode_cachep, qnx4_i(inode));
533 }
534
535 static void init_once(void *foo, kmem_cache_t * cachep,
536                       unsigned long flags)
537 {
538         struct qnx4_inode_info *ei = (struct qnx4_inode_info *) foo;
539
540         if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
541             SLAB_CTOR_CONSTRUCTOR)
542                 inode_init_once(&ei->vfs_inode);
543 }
544
545 static int init_inodecache(void)
546 {
547         qnx4_inode_cachep = kmem_cache_create("qnx4_inode_cache",
548                                              sizeof(struct qnx4_inode_info),
549                                              0, (SLAB_RECLAIM_ACCOUNT|
550                                                 SLAB_MEM_SPREAD),
551                                              init_once, NULL);
552         if (qnx4_inode_cachep == NULL)
553                 return -ENOMEM;
554         return 0;
555 }
556
557 static void destroy_inodecache(void)
558 {
559         if (kmem_cache_destroy(qnx4_inode_cachep))
560                 printk(KERN_INFO
561                        "qnx4_inode_cache: not all structures were freed\n");
562 }
563
564 static int qnx4_get_sb(struct file_system_type *fs_type,
565         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
566 {
567         return get_sb_bdev(fs_type, flags, dev_name, data, qnx4_fill_super,
568                            mnt);
569 }
570
571 static struct file_system_type qnx4_fs_type = {
572         .owner          = THIS_MODULE,
573         .name           = "qnx4",
574         .get_sb         = qnx4_get_sb,
575         .kill_sb        = kill_block_super,
576         .fs_flags       = FS_REQUIRES_DEV,
577 };
578
579 static int __init init_qnx4_fs(void)
580 {
581         int err;
582
583         err = init_inodecache();
584         if (err)
585                 return err;
586
587         err = register_filesystem(&qnx4_fs_type);
588         if (err) {
589                 destroy_inodecache();
590                 return err;
591         }
592
593         printk("QNX4 filesystem 0.2.3 registered.\n");
594         return 0;
595 }
596
597 static void __exit exit_qnx4_fs(void)
598 {
599         unregister_filesystem(&qnx4_fs_type);
600         destroy_inodecache();
601 }
602
603 module_init(init_qnx4_fs)
604 module_exit(exit_qnx4_fs)
605 MODULE_LICENSE("GPL");
606