[PATCH] VFS: Permit filesystem to perform statfs with a known root dentry
[linux-2.6.git] / fs / hfs / super.c
1 /*
2  *  linux/fs/hfs/super.c
3  *
4  * Copyright (C) 1995-1997  Paul H. Hargrove
5  * (C) 2003 Ardis Technologies <roman@ardistech.com>
6  * This file may be distributed under the terms of the GNU General Public License.
7  *
8  * This file contains hfs_read_super(), some of the super_ops and
9  * init_module() and cleanup_module().  The remaining super_ops are in
10  * inode.c since they deal with inodes.
11  *
12  * Based on the minix file system code, (C) 1991, 1992 by Linus Torvalds
13  */
14
15 #include <linux/config.h>
16 #include <linux/module.h>
17 #include <linux/blkdev.h>
18 #include <linux/mount.h>
19 #include <linux/init.h>
20 #include <linux/nls.h>
21 #include <linux/parser.h>
22 #include <linux/seq_file.h>
23 #include <linux/vfs.h>
24
25 #include "hfs_fs.h"
26 #include "btree.h"
27
28 static kmem_cache_t *hfs_inode_cachep;
29
30 MODULE_LICENSE("GPL");
31
32 /*
33  * hfs_write_super()
34  *
35  * Description:
36  *   This function is called by the VFS only. When the filesystem
37  *   is mounted r/w it updates the MDB on disk.
38  * Input Variable(s):
39  *   struct super_block *sb: Pointer to the hfs superblock
40  * Output Variable(s):
41  *   NONE
42  * Returns:
43  *   void
44  * Preconditions:
45  *   'sb' points to a "valid" (struct super_block).
46  * Postconditions:
47  *   The MDB is marked 'unsuccessfully unmounted' by clearing bit 8 of drAtrb
48  *   (hfs_put_super() must set this flag!). Some MDB fields are updated
49  *   and the MDB buffer is written to disk by calling hfs_mdb_commit().
50  */
51 static void hfs_write_super(struct super_block *sb)
52 {
53         sb->s_dirt = 0;
54         if (sb->s_flags & MS_RDONLY)
55                 return;
56         /* sync everything to the buffers */
57         hfs_mdb_commit(sb);
58 }
59
60 /*
61  * hfs_put_super()
62  *
63  * This is the put_super() entry in the super_operations structure for
64  * HFS filesystems.  The purpose is to release the resources
65  * associated with the superblock sb.
66  */
67 static void hfs_put_super(struct super_block *sb)
68 {
69         hfs_mdb_close(sb);
70         /* release the MDB's resources */
71         hfs_mdb_put(sb);
72 }
73
74 /*
75  * hfs_statfs()
76  *
77  * This is the statfs() entry in the super_operations structure for
78  * HFS filesystems.  The purpose is to return various data about the
79  * filesystem.
80  *
81  * changed f_files/f_ffree to reflect the fs_ablock/free_ablocks.
82  */
83 static int hfs_statfs(struct dentry *dentry, struct kstatfs *buf)
84 {
85         struct super_block *sb = dentry->d_sb;
86
87         buf->f_type = HFS_SUPER_MAGIC;
88         buf->f_bsize = sb->s_blocksize;
89         buf->f_blocks = (u32)HFS_SB(sb)->fs_ablocks * HFS_SB(sb)->fs_div;
90         buf->f_bfree = (u32)HFS_SB(sb)->free_ablocks * HFS_SB(sb)->fs_div;
91         buf->f_bavail = buf->f_bfree;
92         buf->f_files = HFS_SB(sb)->fs_ablocks;
93         buf->f_ffree = HFS_SB(sb)->free_ablocks;
94         buf->f_namelen = HFS_NAMELEN;
95
96         return 0;
97 }
98
99 static int hfs_remount(struct super_block *sb, int *flags, char *data)
100 {
101         *flags |= MS_NODIRATIME;
102         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
103                 return 0;
104         if (!(*flags & MS_RDONLY)) {
105                 if (!(HFS_SB(sb)->mdb->drAtrb & cpu_to_be16(HFS_SB_ATTRIB_UNMNT))) {
106                         printk(KERN_WARNING "hfs: filesystem was not cleanly unmounted, "
107                                "running fsck.hfs is recommended.  leaving read-only.\n");
108                         sb->s_flags |= MS_RDONLY;
109                         *flags |= MS_RDONLY;
110                 } else if (HFS_SB(sb)->mdb->drAtrb & cpu_to_be16(HFS_SB_ATTRIB_SLOCK)) {
111                         printk(KERN_WARNING "hfs: filesystem is marked locked, leaving read-only.\n");
112                         sb->s_flags |= MS_RDONLY;
113                         *flags |= MS_RDONLY;
114                 }
115         }
116         return 0;
117 }
118
119 static int hfs_show_options(struct seq_file *seq, struct vfsmount *mnt)
120 {
121         struct hfs_sb_info *sbi = HFS_SB(mnt->mnt_sb);
122
123         if (sbi->s_creator != cpu_to_be32(0x3f3f3f3f))
124                 seq_printf(seq, ",creator=%.4s", (char *)&sbi->s_creator);
125         if (sbi->s_type != cpu_to_be32(0x3f3f3f3f))
126                 seq_printf(seq, ",type=%.4s", (char *)&sbi->s_type);
127         seq_printf(seq, ",uid=%u,gid=%u", sbi->s_uid, sbi->s_gid);
128         if (sbi->s_file_umask != 0133)
129                 seq_printf(seq, ",file_umask=%o", sbi->s_file_umask);
130         if (sbi->s_dir_umask != 0022)
131                 seq_printf(seq, ",dir_umask=%o", sbi->s_dir_umask);
132         if (sbi->part >= 0)
133                 seq_printf(seq, ",part=%u", sbi->part);
134         if (sbi->session >= 0)
135                 seq_printf(seq, ",session=%u", sbi->session);
136         if (sbi->nls_disk)
137                 seq_printf(seq, ",codepage=%s", sbi->nls_disk->charset);
138         if (sbi->nls_io)
139                 seq_printf(seq, ",iocharset=%s", sbi->nls_io->charset);
140         if (sbi->s_quiet)
141                 seq_printf(seq, ",quiet");
142         return 0;
143 }
144
145 static struct inode *hfs_alloc_inode(struct super_block *sb)
146 {
147         struct hfs_inode_info *i;
148
149         i = kmem_cache_alloc(hfs_inode_cachep, SLAB_KERNEL);
150         return i ? &i->vfs_inode : NULL;
151 }
152
153 static void hfs_destroy_inode(struct inode *inode)
154 {
155         kmem_cache_free(hfs_inode_cachep, HFS_I(inode));
156 }
157
158 static struct super_operations hfs_super_operations = {
159         .alloc_inode    = hfs_alloc_inode,
160         .destroy_inode  = hfs_destroy_inode,
161         .write_inode    = hfs_write_inode,
162         .clear_inode    = hfs_clear_inode,
163         .put_super      = hfs_put_super,
164         .write_super    = hfs_write_super,
165         .statfs         = hfs_statfs,
166         .remount_fs     = hfs_remount,
167         .show_options   = hfs_show_options,
168 };
169
170 enum {
171         opt_uid, opt_gid, opt_umask, opt_file_umask, opt_dir_umask,
172         opt_part, opt_session, opt_type, opt_creator, opt_quiet,
173         opt_codepage, opt_iocharset,
174         opt_err
175 };
176
177 static match_table_t tokens = {
178         { opt_uid, "uid=%u" },
179         { opt_gid, "gid=%u" },
180         { opt_umask, "umask=%o" },
181         { opt_file_umask, "file_umask=%o" },
182         { opt_dir_umask, "dir_umask=%o" },
183         { opt_part, "part=%u" },
184         { opt_session, "session=%u" },
185         { opt_type, "type=%s" },
186         { opt_creator, "creator=%s" },
187         { opt_quiet, "quiet" },
188         { opt_codepage, "codepage=%s" },
189         { opt_iocharset, "iocharset=%s" },
190         { opt_err, NULL }
191 };
192
193 static inline int match_fourchar(substring_t *arg, u32 *result)
194 {
195         if (arg->to - arg->from != 4)
196                 return -EINVAL;
197         memcpy(result, arg->from, 4);
198         return 0;
199 }
200
201 /*
202  * parse_options()
203  *
204  * adapted from linux/fs/msdos/inode.c written 1992,93 by Werner Almesberger
205  * This function is called by hfs_read_super() to parse the mount options.
206  */
207 static int parse_options(char *options, struct hfs_sb_info *hsb)
208 {
209         char *p;
210         substring_t args[MAX_OPT_ARGS];
211         int tmp, token;
212
213         /* initialize the sb with defaults */
214         hsb->s_uid = current->uid;
215         hsb->s_gid = current->gid;
216         hsb->s_file_umask = 0133;
217         hsb->s_dir_umask = 0022;
218         hsb->s_type = hsb->s_creator = cpu_to_be32(0x3f3f3f3f); /* == '????' */
219         hsb->s_quiet = 0;
220         hsb->part = -1;
221         hsb->session = -1;
222
223         if (!options)
224                 return 1;
225
226         while ((p = strsep(&options, ",")) != NULL) {
227                 if (!*p)
228                         continue;
229
230                 token = match_token(p, tokens, args);
231                 switch (token) {
232                 case opt_uid:
233                         if (match_int(&args[0], &tmp)) {
234                                 printk(KERN_ERR "hfs: uid requires an argument\n");
235                                 return 0;
236                         }
237                         hsb->s_uid = (uid_t)tmp;
238                         break;
239                 case opt_gid:
240                         if (match_int(&args[0], &tmp)) {
241                                 printk(KERN_ERR "hfs: gid requires an argument\n");
242                                 return 0;
243                         }
244                         hsb->s_gid = (gid_t)tmp;
245                         break;
246                 case opt_umask:
247                         if (match_octal(&args[0], &tmp)) {
248                                 printk(KERN_ERR "hfs: umask requires a value\n");
249                                 return 0;
250                         }
251                         hsb->s_file_umask = (umode_t)tmp;
252                         hsb->s_dir_umask = (umode_t)tmp;
253                         break;
254                 case opt_file_umask:
255                         if (match_octal(&args[0], &tmp)) {
256                                 printk(KERN_ERR "hfs: file_umask requires a value\n");
257                                 return 0;
258                         }
259                         hsb->s_file_umask = (umode_t)tmp;
260                         break;
261                 case opt_dir_umask:
262                         if (match_octal(&args[0], &tmp)) {
263                                 printk(KERN_ERR "hfs: dir_umask requires a value\n");
264                                 return 0;
265                         }
266                         hsb->s_dir_umask = (umode_t)tmp;
267                         break;
268                 case opt_part:
269                         if (match_int(&args[0], &hsb->part)) {
270                                 printk(KERN_ERR "hfs: part requires an argument\n");
271                                 return 0;
272                         }
273                         break;
274                 case opt_session:
275                         if (match_int(&args[0], &hsb->session)) {
276                                 printk(KERN_ERR "hfs: session requires an argument\n");
277                                 return 0;
278                         }
279                         break;
280                 case opt_type:
281                         if (match_fourchar(&args[0], &hsb->s_type)) {
282                                 printk(KERN_ERR "hfs: type requires a 4 character value\n");
283                                 return 0;
284                         }
285                         break;
286                 case opt_creator:
287                         if (match_fourchar(&args[0], &hsb->s_creator)) {
288                                 printk(KERN_ERR "hfs: creator requires a 4 character value\n");
289                                 return 0;
290                         }
291                         break;
292                 case opt_quiet:
293                         hsb->s_quiet = 1;
294                         break;
295                 case opt_codepage:
296                         if (hsb->nls_disk) {
297                                 printk(KERN_ERR "hfs: unable to change codepage\n");
298                                 return 0;
299                         }
300                         p = match_strdup(&args[0]);
301                         hsb->nls_disk = load_nls(p);
302                         if (!hsb->nls_disk) {
303                                 printk(KERN_ERR "hfs: unable to load codepage \"%s\"\n", p);
304                                 kfree(p);
305                                 return 0;
306                         }
307                         kfree(p);
308                         break;
309                 case opt_iocharset:
310                         if (hsb->nls_io) {
311                                 printk(KERN_ERR "hfs: unable to change iocharset\n");
312                                 return 0;
313                         }
314                         p = match_strdup(&args[0]);
315                         hsb->nls_io = load_nls(p);
316                         if (!hsb->nls_io) {
317                                 printk(KERN_ERR "hfs: unable to load iocharset \"%s\"\n", p);
318                                 kfree(p);
319                                 return 0;
320                         }
321                         kfree(p);
322                         break;
323                 default:
324                         return 0;
325                 }
326         }
327
328         if (hsb->nls_disk && !hsb->nls_io) {
329                 hsb->nls_io = load_nls_default();
330                 if (!hsb->nls_io) {
331                         printk(KERN_ERR "hfs: unable to load default iocharset\n");
332                         return 0;
333                 }
334         }
335         hsb->s_dir_umask &= 0777;
336         hsb->s_file_umask &= 0577;
337
338         return 1;
339 }
340
341 /*
342  * hfs_read_super()
343  *
344  * This is the function that is responsible for mounting an HFS
345  * filesystem.  It performs all the tasks necessary to get enough data
346  * from the disk to read the root inode.  This includes parsing the
347  * mount options, dealing with Macintosh partitions, reading the
348  * superblock and the allocation bitmap blocks, calling
349  * hfs_btree_init() to get the necessary data about the extents and
350  * catalog B-trees and, finally, reading the root inode into memory.
351  */
352 static int hfs_fill_super(struct super_block *sb, void *data, int silent)
353 {
354         struct hfs_sb_info *sbi;
355         struct hfs_find_data fd;
356         hfs_cat_rec rec;
357         struct inode *root_inode;
358         int res;
359
360         sbi = kmalloc(sizeof(struct hfs_sb_info), GFP_KERNEL);
361         if (!sbi)
362                 return -ENOMEM;
363         sb->s_fs_info = sbi;
364         memset(sbi, 0, sizeof(struct hfs_sb_info));
365         INIT_HLIST_HEAD(&sbi->rsrc_inodes);
366
367         res = -EINVAL;
368         if (!parse_options((char *)data, sbi)) {
369                 printk(KERN_ERR "hfs: unable to parse mount options.\n");
370                 goto bail;
371         }
372
373         sb->s_op = &hfs_super_operations;
374         sb->s_flags |= MS_NODIRATIME;
375         init_MUTEX(&sbi->bitmap_lock);
376
377         res = hfs_mdb_get(sb);
378         if (res) {
379                 if (!silent)
380                         printk(KERN_WARNING "hfs: can't find a HFS filesystem on dev %s.\n",
381                                 hfs_mdb_name(sb));
382                 res = -EINVAL;
383                 goto bail;
384         }
385
386         /* try to get the root inode */
387         hfs_find_init(HFS_SB(sb)->cat_tree, &fd);
388         res = hfs_cat_find_brec(sb, HFS_ROOT_CNID, &fd);
389         if (!res)
390                 hfs_bnode_read(fd.bnode, &rec, fd.entryoffset, fd.entrylength);
391         if (res) {
392                 hfs_find_exit(&fd);
393                 goto bail_no_root;
394         }
395         root_inode = hfs_iget(sb, &fd.search_key->cat, &rec);
396         hfs_find_exit(&fd);
397         if (!root_inode)
398                 goto bail_no_root;
399
400         sb->s_root = d_alloc_root(root_inode);
401         if (!sb->s_root)
402                 goto bail_iput;
403
404         sb->s_root->d_op = &hfs_dentry_operations;
405
406         /* everything's okay */
407         return 0;
408
409 bail_iput:
410         iput(root_inode);
411 bail_no_root:
412         printk(KERN_ERR "hfs: get root inode failed.\n");
413 bail:
414         hfs_mdb_put(sb);
415         return res;
416 }
417
418 static int hfs_get_sb(struct file_system_type *fs_type,
419                       int flags, const char *dev_name, void *data,
420                       struct vfsmount *mnt)
421 {
422         return get_sb_bdev(fs_type, flags, dev_name, data, hfs_fill_super, mnt);
423 }
424
425 static struct file_system_type hfs_fs_type = {
426         .owner          = THIS_MODULE,
427         .name           = "hfs",
428         .get_sb         = hfs_get_sb,
429         .kill_sb        = kill_block_super,
430         .fs_flags       = FS_REQUIRES_DEV,
431 };
432
433 static void hfs_init_once(void *p, kmem_cache_t *cachep, unsigned long flags)
434 {
435         struct hfs_inode_info *i = p;
436
437         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == SLAB_CTOR_CONSTRUCTOR)
438                 inode_init_once(&i->vfs_inode);
439 }
440
441 static int __init init_hfs_fs(void)
442 {
443         int err;
444
445         hfs_inode_cachep = kmem_cache_create("hfs_inode_cache",
446                 sizeof(struct hfs_inode_info), 0, SLAB_HWCACHE_ALIGN,
447                 hfs_init_once, NULL);
448         if (!hfs_inode_cachep)
449                 return -ENOMEM;
450         err = register_filesystem(&hfs_fs_type);
451         if (err)
452                 kmem_cache_destroy(hfs_inode_cachep);
453         return err;
454 }
455
456 static void __exit exit_hfs_fs(void)
457 {
458         unregister_filesystem(&hfs_fs_type);
459         if (kmem_cache_destroy(hfs_inode_cachep))
460                 printk(KERN_ERR "hfs_inode_cache: not all structures were freed\n");
461 }
462
463 module_init(init_hfs_fs)
464 module_exit(exit_hfs_fs)