[PATCH] s390_hypfs filesystem
[linux-2.6.git] / arch / s390 / hypfs / inode.c
1 /*
2  *  fs/hypfs/inode.c
3  *    Hypervisor filesystem for Linux on s390.
4  *
5  *    Copyright (C) IBM Corp. 2006
6  *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
7  */
8
9 #include <linux/types.h>
10 #include <linux/errno.h>
11 #include <linux/fs.h>
12 #include <linux/namei.h>
13 #include <linux/vfs.h>
14 #include <linux/pagemap.h>
15 #include <linux/gfp.h>
16 #include <linux/time.h>
17 #include <linux/parser.h>
18 #include <linux/sysfs.h>
19 #include <linux/module.h>
20 #include <asm/ebcdic.h>
21 #include "hypfs.h"
22 #include "hypfs_diag.h"
23
24 #define HYPFS_MAGIC 0x687970    /* ASCII 'hyp' */
25 #define TMP_SIZE 64             /* size of temporary buffers */
26
27 static struct dentry *hypfs_create_update_file(struct super_block *sb,
28                                                struct dentry *dir);
29
30 struct hypfs_sb_info {
31         uid_t uid;                      /* uid used for files and dirs */
32         gid_t gid;                      /* gid used for files and dirs */
33         struct dentry *update_file;     /* file to trigger update */
34         time_t last_update;             /* last update time in secs since 1970 */
35         struct mutex lock;              /* lock to protect update process */
36 };
37
38 static struct file_operations hypfs_file_ops;
39 static struct file_system_type hypfs_type;
40 static struct super_operations hypfs_s_ops;
41
42 /* start of list of all dentries, which have to be deleted on update */
43 static struct dentry *hypfs_last_dentry;
44
45 static void hypfs_update_update(struct super_block *sb)
46 {
47         struct hypfs_sb_info *sb_info = sb->s_fs_info;
48         struct inode *inode = sb_info->update_file->d_inode;
49
50         sb_info->last_update = get_seconds();
51         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
52 }
53
54 /* directory tree removal functions */
55
56 static void hypfs_add_dentry(struct dentry *dentry)
57 {
58         dentry->d_fsdata = hypfs_last_dentry;
59         hypfs_last_dentry = dentry;
60 }
61
62 static void hypfs_remove(struct dentry *dentry)
63 {
64         struct dentry *parent;
65
66         parent = dentry->d_parent;
67         if (S_ISDIR(dentry->d_inode->i_mode))
68                 simple_rmdir(parent->d_inode, dentry);
69         else
70                 simple_unlink(parent->d_inode, dentry);
71         d_delete(dentry);
72         dput(dentry);
73 }
74
75 static void hypfs_delete_tree(struct dentry *root)
76 {
77         while (hypfs_last_dentry) {
78                 struct dentry *next_dentry;
79                 next_dentry = hypfs_last_dentry->d_fsdata;
80                 hypfs_remove(hypfs_last_dentry);
81                 hypfs_last_dentry = next_dentry;
82         }
83 }
84
85 static struct inode *hypfs_make_inode(struct super_block *sb, int mode)
86 {
87         struct inode *ret = new_inode(sb);
88
89         if (ret) {
90                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
91                 ret->i_mode = mode;
92                 ret->i_uid = hypfs_info->uid;
93                 ret->i_gid = hypfs_info->gid;
94                 ret->i_blksize = PAGE_CACHE_SIZE;
95                 ret->i_blocks = 0;
96                 ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
97                 if (mode & S_IFDIR)
98                         ret->i_nlink = 2;
99                 else
100                         ret->i_nlink = 1;
101         }
102         return ret;
103 }
104
105 static void hypfs_drop_inode(struct inode *inode)
106 {
107         kfree(inode->u.generic_ip);
108         generic_delete_inode(inode);
109 }
110
111 static int hypfs_open(struct inode *inode, struct file *filp)
112 {
113         char *data = filp->f_dentry->d_inode->u.generic_ip;
114         struct hypfs_sb_info *fs_info;
115
116         if (filp->f_mode & FMODE_WRITE) {
117                 if (!(inode->i_mode & S_IWUGO))
118                         return -EACCES;
119         }
120         if (filp->f_mode & FMODE_READ) {
121                 if (!(inode->i_mode & S_IRUGO))
122                         return -EACCES;
123         }
124
125         fs_info = inode->i_sb->s_fs_info;
126         if(data) {
127                 mutex_lock(&fs_info->lock);
128                 filp->private_data = kstrdup(data, GFP_KERNEL);
129                 if (!filp->private_data) {
130                         mutex_unlock(&fs_info->lock);
131                         return -ENOMEM;
132                 }
133                 mutex_unlock(&fs_info->lock);
134         }
135         return 0;
136 }
137
138 static ssize_t hypfs_aio_read(struct kiocb *iocb, __user char *buf,
139                               size_t count, loff_t offset)
140 {
141         char *data;
142         size_t len;
143         struct file *filp = iocb->ki_filp;
144
145         data = filp->private_data;
146         len = strlen(data);
147         if (offset > len) {
148                 count = 0;
149                 goto out;
150         }
151         if (count > len - offset)
152                 count = len - offset;
153         if (copy_to_user(buf, data + offset, count)) {
154                 count = -EFAULT;
155                 goto out;
156         }
157         iocb->ki_pos += count;
158         file_accessed(filp);
159 out:
160         return count;
161 }
162 static ssize_t hypfs_aio_write(struct kiocb *iocb, const char __user *buf,
163                                size_t count, loff_t pos)
164 {
165         int rc;
166         struct super_block *sb;
167         struct hypfs_sb_info *fs_info;
168
169         sb = iocb->ki_filp->f_dentry->d_inode->i_sb;
170         fs_info = sb->s_fs_info;
171         /*
172          * Currently we only allow one update per second for two reasons:
173          * 1. diag 204 is VERY expensive
174          * 2. If several processes do updates in parallel and then read the
175          *    hypfs data, the likelihood of collisions is reduced, if we restrict
176          *    the minimum update interval. A collision occurs, if during the
177          *    data gathering of one process another process triggers an update
178          *    If the first process wants to ensure consistent data, it has
179          *    to restart data collection in this case.
180          */
181         mutex_lock(&fs_info->lock);
182         if (fs_info->last_update == get_seconds()) {
183                 rc = -EBUSY;
184                 goto out;
185         }
186         hypfs_delete_tree(sb->s_root);
187         rc = hypfs_diag_create_files(sb, sb->s_root);
188         if (rc) {
189                 printk(KERN_ERR "hypfs: Update failed\n");
190                 hypfs_delete_tree(sb->s_root);
191                 goto out;
192         }
193         hypfs_update_update(sb);
194         rc = count;
195 out:
196         mutex_unlock(&fs_info->lock);
197         return rc;
198 }
199
200 static int hypfs_release(struct inode *inode, struct file *filp)
201 {
202         kfree(filp->private_data);
203         return 0;
204 }
205
206 enum { opt_uid, opt_gid, opt_err };
207
208 static match_table_t hypfs_tokens = {
209         {opt_uid, "uid=%u"},
210         {opt_gid, "gid=%u"},
211         {opt_err, NULL}
212 };
213
214 static int hypfs_parse_options(char *options, struct super_block *sb)
215 {
216         char *str;
217         substring_t args[MAX_OPT_ARGS];
218
219         if (!options)
220                 return 0;
221         while ((str = strsep(&options, ",")) != NULL) {
222                 int token, option;
223                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
224
225                 if (!*str)
226                         continue;
227                 token = match_token(str, hypfs_tokens, args);
228                 switch (token) {
229                 case opt_uid:
230                         if (match_int(&args[0], &option))
231                                 return -EINVAL;
232                         hypfs_info->uid = option;
233                         break;
234                 case opt_gid:
235                         if (match_int(&args[0], &option))
236                                 return -EINVAL;
237                         hypfs_info->gid = option;
238                         break;
239                 case opt_err:
240                 default:
241                         printk(KERN_ERR "hypfs: Unrecognized mount option "
242                                "\"%s\" or missing value\n", str);
243                         return -EINVAL;
244                 }
245         }
246         return 0;
247 }
248
249 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
250 {
251         struct inode *root_inode;
252         struct dentry *root_dentry;
253         int rc = 0;
254         struct hypfs_sb_info *sbi;
255
256         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
257         if (!sbi)
258                 return -ENOMEM;
259         mutex_init(&sbi->lock);
260         sbi->uid = current->uid;
261         sbi->gid = current->gid;
262         sb->s_fs_info = sbi;
263         sb->s_blocksize = PAGE_CACHE_SIZE;
264         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
265         sb->s_magic = HYPFS_MAGIC;
266         sb->s_op = &hypfs_s_ops;
267         if (hypfs_parse_options(data, sb)) {
268                 rc = -EINVAL;
269                 goto err_alloc;
270         }
271         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
272         if (!root_inode) {
273                 rc = -ENOMEM;
274                 goto err_alloc;
275         }
276         root_inode->i_op = &simple_dir_inode_operations;
277         root_inode->i_fop = &simple_dir_operations;
278         root_dentry = d_alloc_root(root_inode);
279         if (!root_dentry) {
280                 iput(root_inode);
281                 rc = -ENOMEM;
282                 goto err_alloc;
283         }
284         rc = hypfs_diag_create_files(sb, root_dentry);
285         if (rc)
286                 goto err_tree;
287         sbi->update_file = hypfs_create_update_file(sb, root_dentry);
288         if (IS_ERR(sbi->update_file)) {
289                 rc = PTR_ERR(sbi->update_file);
290                 goto err_tree;
291         }
292         hypfs_update_update(sb);
293         sb->s_root = root_dentry;
294         return 0;
295
296 err_tree:
297         hypfs_delete_tree(root_dentry);
298         d_genocide(root_dentry);
299         dput(root_dentry);
300 err_alloc:
301         kfree(sbi);
302         return rc;
303 }
304
305 static struct super_block *hypfs_get_super(struct file_system_type *fst,
306                                            int flags, const char *devname,
307                                            void *data)
308 {
309         return get_sb_single(fst, flags, data, hypfs_fill_super);
310 }
311
312 static void hypfs_kill_super(struct super_block *sb)
313 {
314         struct hypfs_sb_info *sb_info = sb->s_fs_info;
315
316         hypfs_delete_tree(sb->s_root);
317         hypfs_remove(sb_info->update_file);
318         kfree(sb->s_fs_info);
319         sb->s_fs_info = NULL;
320         kill_litter_super(sb);
321 }
322
323 static struct dentry *hypfs_create_file(struct super_block *sb,
324                                         struct dentry *parent, const char *name,
325                                         char *data, mode_t mode)
326 {
327         struct dentry *dentry;
328         struct inode *inode;
329         struct qstr qname;
330
331         qname.name = name;
332         qname.len = strlen(name);
333         qname.hash = full_name_hash(name, qname.len);
334         dentry = lookup_one_len(name, parent, strlen(name));
335         if (IS_ERR(dentry))
336                 return ERR_PTR(-ENOMEM);
337         inode = hypfs_make_inode(sb, mode);
338         if (!inode) {
339                 dput(dentry);
340                 return ERR_PTR(-ENOMEM);
341         }
342         if (mode & S_IFREG) {
343                 inode->i_fop = &hypfs_file_ops;
344                 if (data)
345                         inode->i_size = strlen(data);
346                 else
347                         inode->i_size = 0;
348         } else if (mode & S_IFDIR) {
349                 inode->i_op = &simple_dir_inode_operations;
350                 inode->i_fop = &simple_dir_operations;
351                 parent->d_inode->i_nlink++;
352         } else
353                 BUG();
354         inode->u.generic_ip = data;
355         d_instantiate(dentry, inode);
356         dget(dentry);
357         return dentry;
358 }
359
360 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
361                            const char *name)
362 {
363         struct dentry *dentry;
364
365         dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
366         if (IS_ERR(dentry))
367                 return dentry;
368         hypfs_add_dentry(dentry);
369         parent->d_inode->i_nlink++;
370         return dentry;
371 }
372
373 static struct dentry *hypfs_create_update_file(struct super_block *sb,
374                                                struct dentry *dir)
375 {
376         struct dentry *dentry;
377
378         dentry = hypfs_create_file(sb, dir, "update", NULL,
379                                    S_IFREG | UPDATE_FILE_MODE);
380         /*
381          * We do not put the update file on the 'delete' list with
382          * hypfs_add_dentry(), since it should not be removed when the tree
383          * is updated.
384          */
385         return dentry;
386 }
387
388 struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
389                                 const char *name, __u64 value)
390 {
391         char *buffer;
392         char tmp[TMP_SIZE];
393         struct dentry *dentry;
394
395         snprintf(tmp, TMP_SIZE, "%lld\n", (unsigned long long int)value);
396         buffer = kstrdup(tmp, GFP_KERNEL);
397         if (!buffer)
398                 return ERR_PTR(-ENOMEM);
399         dentry =
400             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
401         if (IS_ERR(dentry)) {
402                 kfree(buffer);
403                 return ERR_PTR(-ENOMEM);
404         }
405         hypfs_add_dentry(dentry);
406         return dentry;
407 }
408
409 struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
410                                 const char *name, char *string)
411 {
412         char *buffer;
413         struct dentry *dentry;
414
415         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
416         if (!buffer)
417                 return ERR_PTR(-ENOMEM);
418         sprintf(buffer, "%s\n", string);
419         dentry =
420             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
421         if (IS_ERR(dentry)) {
422                 kfree(buffer);
423                 return ERR_PTR(-ENOMEM);
424         }
425         hypfs_add_dentry(dentry);
426         return dentry;
427 }
428
429 static struct file_operations hypfs_file_ops = {
430         .open           = hypfs_open,
431         .release        = hypfs_release,
432         .read           = do_sync_read,
433         .write          = do_sync_write,
434         .aio_read       = hypfs_aio_read,
435         .aio_write      = hypfs_aio_write,
436 };
437
438 static struct file_system_type hypfs_type = {
439         .owner          = THIS_MODULE,
440         .name           = "s390_hypfs",
441         .get_sb         = hypfs_get_super,
442         .kill_sb        = hypfs_kill_super
443 };
444
445 static struct super_operations hypfs_s_ops = {
446         .statfs         = simple_statfs,
447         .drop_inode     = hypfs_drop_inode,
448 };
449
450 static decl_subsys(s390, NULL, NULL);
451
452 static int __init hypfs_init(void)
453 {
454         int rc;
455
456         if (MACHINE_IS_VM)
457                 return -ENODATA;
458         if (hypfs_diag_init()) {
459                 rc = -ENODATA;
460                 goto fail_diag;
461         }
462         kset_set_kset_s(&s390_subsys, hypervisor_subsys);
463         rc = subsystem_register(&s390_subsys);
464         if (rc)
465                 goto fail_sysfs;
466         rc = register_filesystem(&hypfs_type);
467         if (rc)
468                 goto fail_filesystem;
469         return 0;
470
471 fail_filesystem:
472         subsystem_unregister(&s390_subsys);
473 fail_sysfs:
474         hypfs_diag_exit();
475 fail_diag:
476         printk(KERN_ERR "hypfs: Initialization failed with rc = %i.\n", rc);
477         return rc;
478 }
479
480 static void __exit hypfs_exit(void)
481 {
482         hypfs_diag_exit();
483         unregister_filesystem(&hypfs_type);
484         subsystem_unregister(&s390_subsys);
485 }
486
487 module_init(hypfs_init)
488 module_exit(hypfs_exit)
489
490 MODULE_LICENSE("GPL");
491 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
492 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");