switch open-coded instances of d_make_root() to new helper
[linux-2.6.git] / arch / s390 / hypfs / inode.c
1 /*
2  *  arch/s390/hypfs/inode.c
3  *    Hypervisor filesystem for Linux on s390.
4  *
5  *    Copyright IBM Corp. 2006, 2008
6  *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
7  */
8
9 #define KMSG_COMPONENT "hypfs"
10 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
11
12 #include <linux/types.h>
13 #include <linux/errno.h>
14 #include <linux/fs.h>
15 #include <linux/namei.h>
16 #include <linux/vfs.h>
17 #include <linux/slab.h>
18 #include <linux/pagemap.h>
19 #include <linux/time.h>
20 #include <linux/parser.h>
21 #include <linux/sysfs.h>
22 #include <linux/module.h>
23 #include <linux/seq_file.h>
24 #include <linux/mount.h>
25 #include <asm/ebcdic.h>
26 #include "hypfs.h"
27
28 #define HYPFS_MAGIC 0x687970    /* ASCII 'hyp' */
29 #define TMP_SIZE 64             /* size of temporary buffers */
30
31 static struct dentry *hypfs_create_update_file(struct super_block *sb,
32                                                struct dentry *dir);
33
34 struct hypfs_sb_info {
35         uid_t uid;                      /* uid used for files and dirs */
36         gid_t gid;                      /* gid used for files and dirs */
37         struct dentry *update_file;     /* file to trigger update */
38         time_t last_update;             /* last update time in secs since 1970 */
39         struct mutex lock;              /* lock to protect update process */
40 };
41
42 static const struct file_operations hypfs_file_ops;
43 static struct file_system_type hypfs_type;
44 static const struct super_operations hypfs_s_ops;
45
46 /* start of list of all dentries, which have to be deleted on update */
47 static struct dentry *hypfs_last_dentry;
48
49 static void hypfs_update_update(struct super_block *sb)
50 {
51         struct hypfs_sb_info *sb_info = sb->s_fs_info;
52         struct inode *inode = sb_info->update_file->d_inode;
53
54         sb_info->last_update = get_seconds();
55         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
56 }
57
58 /* directory tree removal functions */
59
60 static void hypfs_add_dentry(struct dentry *dentry)
61 {
62         dentry->d_fsdata = hypfs_last_dentry;
63         hypfs_last_dentry = dentry;
64 }
65
66 static inline int hypfs_positive(struct dentry *dentry)
67 {
68         return dentry->d_inode && !d_unhashed(dentry);
69 }
70
71 static void hypfs_remove(struct dentry *dentry)
72 {
73         struct dentry *parent;
74
75         parent = dentry->d_parent;
76         if (!parent || !parent->d_inode)
77                 return;
78         mutex_lock(&parent->d_inode->i_mutex);
79         if (hypfs_positive(dentry)) {
80                 if (S_ISDIR(dentry->d_inode->i_mode))
81                         simple_rmdir(parent->d_inode, dentry);
82                 else
83                         simple_unlink(parent->d_inode, dentry);
84         }
85         d_delete(dentry);
86         dput(dentry);
87         mutex_unlock(&parent->d_inode->i_mutex);
88 }
89
90 static void hypfs_delete_tree(struct dentry *root)
91 {
92         while (hypfs_last_dentry) {
93                 struct dentry *next_dentry;
94                 next_dentry = hypfs_last_dentry->d_fsdata;
95                 hypfs_remove(hypfs_last_dentry);
96                 hypfs_last_dentry = next_dentry;
97         }
98 }
99
100 static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
101 {
102         struct inode *ret = new_inode(sb);
103
104         if (ret) {
105                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
106                 ret->i_mode = mode;
107                 ret->i_uid = hypfs_info->uid;
108                 ret->i_gid = hypfs_info->gid;
109                 ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
110                 if (S_ISDIR(mode))
111                         set_nlink(ret, 2);
112         }
113         return ret;
114 }
115
116 static void hypfs_evict_inode(struct inode *inode)
117 {
118         end_writeback(inode);
119         kfree(inode->i_private);
120 }
121
122 static int hypfs_open(struct inode *inode, struct file *filp)
123 {
124         char *data = filp->f_path.dentry->d_inode->i_private;
125         struct hypfs_sb_info *fs_info;
126
127         if (filp->f_mode & FMODE_WRITE) {
128                 if (!(inode->i_mode & S_IWUGO))
129                         return -EACCES;
130         }
131         if (filp->f_mode & FMODE_READ) {
132                 if (!(inode->i_mode & S_IRUGO))
133                         return -EACCES;
134         }
135
136         fs_info = inode->i_sb->s_fs_info;
137         if(data) {
138                 mutex_lock(&fs_info->lock);
139                 filp->private_data = kstrdup(data, GFP_KERNEL);
140                 if (!filp->private_data) {
141                         mutex_unlock(&fs_info->lock);
142                         return -ENOMEM;
143                 }
144                 mutex_unlock(&fs_info->lock);
145         }
146         return nonseekable_open(inode, filp);
147 }
148
149 static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
150                               unsigned long nr_segs, loff_t offset)
151 {
152         char *data;
153         ssize_t ret;
154         struct file *filp = iocb->ki_filp;
155         /* XXX: temporary */
156         char __user *buf = iov[0].iov_base;
157         size_t count = iov[0].iov_len;
158
159         if (nr_segs != 1)
160                 return -EINVAL;
161
162         data = filp->private_data;
163         ret = simple_read_from_buffer(buf, count, &offset, data, strlen(data));
164         if (ret <= 0)
165                 return ret;
166
167         iocb->ki_pos += ret;
168         file_accessed(filp);
169
170         return ret;
171 }
172 static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
173                               unsigned long nr_segs, loff_t offset)
174 {
175         int rc;
176         struct super_block *sb;
177         struct hypfs_sb_info *fs_info;
178         size_t count = iov_length(iov, nr_segs);
179
180         sb = iocb->ki_filp->f_path.dentry->d_inode->i_sb;
181         fs_info = sb->s_fs_info;
182         /*
183          * Currently we only allow one update per second for two reasons:
184          * 1. diag 204 is VERY expensive
185          * 2. If several processes do updates in parallel and then read the
186          *    hypfs data, the likelihood of collisions is reduced, if we restrict
187          *    the minimum update interval. A collision occurs, if during the
188          *    data gathering of one process another process triggers an update
189          *    If the first process wants to ensure consistent data, it has
190          *    to restart data collection in this case.
191          */
192         mutex_lock(&fs_info->lock);
193         if (fs_info->last_update == get_seconds()) {
194                 rc = -EBUSY;
195                 goto out;
196         }
197         hypfs_delete_tree(sb->s_root);
198         if (MACHINE_IS_VM)
199                 rc = hypfs_vm_create_files(sb, sb->s_root);
200         else
201                 rc = hypfs_diag_create_files(sb, sb->s_root);
202         if (rc) {
203                 pr_err("Updating the hypfs tree failed\n");
204                 hypfs_delete_tree(sb->s_root);
205                 goto out;
206         }
207         hypfs_update_update(sb);
208         rc = count;
209 out:
210         mutex_unlock(&fs_info->lock);
211         return rc;
212 }
213
214 static int hypfs_release(struct inode *inode, struct file *filp)
215 {
216         kfree(filp->private_data);
217         return 0;
218 }
219
220 enum { opt_uid, opt_gid, opt_err };
221
222 static const match_table_t hypfs_tokens = {
223         {opt_uid, "uid=%u"},
224         {opt_gid, "gid=%u"},
225         {opt_err, NULL}
226 };
227
228 static int hypfs_parse_options(char *options, struct super_block *sb)
229 {
230         char *str;
231         substring_t args[MAX_OPT_ARGS];
232
233         if (!options)
234                 return 0;
235         while ((str = strsep(&options, ",")) != NULL) {
236                 int token, option;
237                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
238
239                 if (!*str)
240                         continue;
241                 token = match_token(str, hypfs_tokens, args);
242                 switch (token) {
243                 case opt_uid:
244                         if (match_int(&args[0], &option))
245                                 return -EINVAL;
246                         hypfs_info->uid = option;
247                         break;
248                 case opt_gid:
249                         if (match_int(&args[0], &option))
250                                 return -EINVAL;
251                         hypfs_info->gid = option;
252                         break;
253                 case opt_err:
254                 default:
255                         pr_err("%s is not a valid mount option\n", str);
256                         return -EINVAL;
257                 }
258         }
259         return 0;
260 }
261
262 static int hypfs_show_options(struct seq_file *s, struct dentry *root)
263 {
264         struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;
265
266         seq_printf(s, ",uid=%u", hypfs_info->uid);
267         seq_printf(s, ",gid=%u", hypfs_info->gid);
268         return 0;
269 }
270
271 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
272 {
273         struct inode *root_inode;
274         struct dentry *root_dentry;
275         int rc = 0;
276         struct hypfs_sb_info *sbi;
277
278         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
279         if (!sbi)
280                 return -ENOMEM;
281         mutex_init(&sbi->lock);
282         sbi->uid = current_uid();
283         sbi->gid = current_gid();
284         sb->s_fs_info = sbi;
285         sb->s_blocksize = PAGE_CACHE_SIZE;
286         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
287         sb->s_magic = HYPFS_MAGIC;
288         sb->s_op = &hypfs_s_ops;
289         if (hypfs_parse_options(data, sb))
290                 return -EINVAL;
291         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
292         if (!root_inode)
293                 return -ENOMEM;
294         root_inode->i_op = &simple_dir_inode_operations;
295         root_inode->i_fop = &simple_dir_operations;
296         sb->s_root = root_dentry = d_make_root(root_inode);
297         if (!root_dentry)
298                 return -ENOMEM;
299         if (MACHINE_IS_VM)
300                 rc = hypfs_vm_create_files(sb, root_dentry);
301         else
302                 rc = hypfs_diag_create_files(sb, root_dentry);
303         if (rc)
304                 return rc;
305         sbi->update_file = hypfs_create_update_file(sb, root_dentry);
306         if (IS_ERR(sbi->update_file))
307                 return PTR_ERR(sbi->update_file);
308         hypfs_update_update(sb);
309         pr_info("Hypervisor filesystem mounted\n");
310         return 0;
311 }
312
313 static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
314                         const char *devname, void *data)
315 {
316         return mount_single(fst, flags, data, hypfs_fill_super);
317 }
318
319 static void hypfs_kill_super(struct super_block *sb)
320 {
321         struct hypfs_sb_info *sb_info = sb->s_fs_info;
322
323         if (sb->s_root)
324                 hypfs_delete_tree(sb->s_root);
325         if (sb_info->update_file)
326                 hypfs_remove(sb_info->update_file);
327         kfree(sb->s_fs_info);
328         sb->s_fs_info = NULL;
329         kill_litter_super(sb);
330 }
331
332 static struct dentry *hypfs_create_file(struct super_block *sb,
333                                         struct dentry *parent, const char *name,
334                                         char *data, umode_t mode)
335 {
336         struct dentry *dentry;
337         struct inode *inode;
338
339         mutex_lock(&parent->d_inode->i_mutex);
340         dentry = lookup_one_len(name, parent, strlen(name));
341         if (IS_ERR(dentry)) {
342                 dentry = ERR_PTR(-ENOMEM);
343                 goto fail;
344         }
345         inode = hypfs_make_inode(sb, mode);
346         if (!inode) {
347                 dput(dentry);
348                 dentry = ERR_PTR(-ENOMEM);
349                 goto fail;
350         }
351         if (S_ISREG(mode)) {
352                 inode->i_fop = &hypfs_file_ops;
353                 if (data)
354                         inode->i_size = strlen(data);
355                 else
356                         inode->i_size = 0;
357         } else if (S_ISDIR(mode)) {
358                 inode->i_op = &simple_dir_inode_operations;
359                 inode->i_fop = &simple_dir_operations;
360                 inc_nlink(parent->d_inode);
361         } else
362                 BUG();
363         inode->i_private = data;
364         d_instantiate(dentry, inode);
365         dget(dentry);
366 fail:
367         mutex_unlock(&parent->d_inode->i_mutex);
368         return dentry;
369 }
370
371 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
372                            const char *name)
373 {
374         struct dentry *dentry;
375
376         dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
377         if (IS_ERR(dentry))
378                 return dentry;
379         hypfs_add_dentry(dentry);
380         return dentry;
381 }
382
383 static struct dentry *hypfs_create_update_file(struct super_block *sb,
384                                                struct dentry *dir)
385 {
386         struct dentry *dentry;
387
388         dentry = hypfs_create_file(sb, dir, "update", NULL,
389                                    S_IFREG | UPDATE_FILE_MODE);
390         /*
391          * We do not put the update file on the 'delete' list with
392          * hypfs_add_dentry(), since it should not be removed when the tree
393          * is updated.
394          */
395         return dentry;
396 }
397
398 struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
399                                 const char *name, __u64 value)
400 {
401         char *buffer;
402         char tmp[TMP_SIZE];
403         struct dentry *dentry;
404
405         snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
406         buffer = kstrdup(tmp, GFP_KERNEL);
407         if (!buffer)
408                 return ERR_PTR(-ENOMEM);
409         dentry =
410             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
411         if (IS_ERR(dentry)) {
412                 kfree(buffer);
413                 return ERR_PTR(-ENOMEM);
414         }
415         hypfs_add_dentry(dentry);
416         return dentry;
417 }
418
419 struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
420                                 const char *name, char *string)
421 {
422         char *buffer;
423         struct dentry *dentry;
424
425         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
426         if (!buffer)
427                 return ERR_PTR(-ENOMEM);
428         sprintf(buffer, "%s\n", string);
429         dentry =
430             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
431         if (IS_ERR(dentry)) {
432                 kfree(buffer);
433                 return ERR_PTR(-ENOMEM);
434         }
435         hypfs_add_dentry(dentry);
436         return dentry;
437 }
438
439 static const struct file_operations hypfs_file_ops = {
440         .open           = hypfs_open,
441         .release        = hypfs_release,
442         .read           = do_sync_read,
443         .write          = do_sync_write,
444         .aio_read       = hypfs_aio_read,
445         .aio_write      = hypfs_aio_write,
446         .llseek         = no_llseek,
447 };
448
449 static struct file_system_type hypfs_type = {
450         .owner          = THIS_MODULE,
451         .name           = "s390_hypfs",
452         .mount          = hypfs_mount,
453         .kill_sb        = hypfs_kill_super
454 };
455
456 static const struct super_operations hypfs_s_ops = {
457         .statfs         = simple_statfs,
458         .evict_inode    = hypfs_evict_inode,
459         .show_options   = hypfs_show_options,
460 };
461
462 static struct kobject *s390_kobj;
463
464 static int __init hypfs_init(void)
465 {
466         int rc;
467
468         rc = hypfs_dbfs_init();
469         if (rc)
470                 return rc;
471         if (hypfs_diag_init()) {
472                 rc = -ENODATA;
473                 goto fail_dbfs_exit;
474         }
475         if (hypfs_vm_init()) {
476                 rc = -ENODATA;
477                 goto fail_hypfs_diag_exit;
478         }
479         s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
480         if (!s390_kobj) {
481                 rc = -ENOMEM;
482                 goto fail_hypfs_vm_exit;
483         }
484         rc = register_filesystem(&hypfs_type);
485         if (rc)
486                 goto fail_filesystem;
487         return 0;
488
489 fail_filesystem:
490         kobject_put(s390_kobj);
491 fail_hypfs_vm_exit:
492         hypfs_vm_exit();
493 fail_hypfs_diag_exit:
494         hypfs_diag_exit();
495 fail_dbfs_exit:
496         hypfs_dbfs_exit();
497         pr_err("Initialization of hypfs failed with rc=%i\n", rc);
498         return rc;
499 }
500
501 static void __exit hypfs_exit(void)
502 {
503         hypfs_diag_exit();
504         hypfs_vm_exit();
505         hypfs_dbfs_exit();
506         unregister_filesystem(&hypfs_type);
507         kobject_put(s390_kobj);
508 }
509
510 module_init(hypfs_init)
511 module_exit(hypfs_exit)
512
513 MODULE_LICENSE("GPL");
514 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
515 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");