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Linux/arch/s390/hypfs/inode.c

  1 /*
  2  *    Hypervisor filesystem for Linux on s390.
  3  *
  4  *    Copyright IBM Corp. 2006, 2008
  5  *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
  6  */
  7 
  8 #define KMSG_COMPONENT "hypfs"
  9 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
 10 
 11 #include <linux/types.h>
 12 #include <linux/errno.h>
 13 #include <linux/fs.h>
 14 #include <linux/namei.h>
 15 #include <linux/vfs.h>
 16 #include <linux/slab.h>
 17 #include <linux/pagemap.h>
 18 #include <linux/time.h>
 19 #include <linux/parser.h>
 20 #include <linux/sysfs.h>
 21 #include <linux/module.h>
 22 #include <linux/seq_file.h>
 23 #include <linux/mount.h>
 24 #include <linux/uio.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 dentry *dir);
 32 
 33 struct hypfs_sb_info {
 34         kuid_t uid;                     /* uid used for files and dirs */
 35         kgid_t gid;                     /* gid used for files and dirs */
 36         struct dentry *update_file;     /* file to trigger update */
 37         time_t last_update;             /* last update time in secs since 1970 */
 38         struct mutex lock;              /* lock to protect update process */
 39 };
 40 
 41 static const struct file_operations hypfs_file_ops;
 42 static struct file_system_type hypfs_type;
 43 static const struct super_operations hypfs_s_ops;
 44 
 45 /* start of list of all dentries, which have to be deleted on update */
 46 static struct dentry *hypfs_last_dentry;
 47 
 48 static void hypfs_update_update(struct super_block *sb)
 49 {
 50         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 51         struct inode *inode = d_inode(sb_info->update_file);
 52 
 53         sb_info->last_update = get_seconds();
 54         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 55 }
 56 
 57 /* directory tree removal functions */
 58 
 59 static void hypfs_add_dentry(struct dentry *dentry)
 60 {
 61         dentry->d_fsdata = hypfs_last_dentry;
 62         hypfs_last_dentry = dentry;
 63 }
 64 
 65 static void hypfs_remove(struct dentry *dentry)
 66 {
 67         struct dentry *parent;
 68 
 69         parent = dentry->d_parent;
 70         mutex_lock(&d_inode(parent)->i_mutex);
 71         if (simple_positive(dentry)) {
 72                 if (d_is_dir(dentry))
 73                         simple_rmdir(d_inode(parent), dentry);
 74                 else
 75                         simple_unlink(d_inode(parent), dentry);
 76         }
 77         d_delete(dentry);
 78         dput(dentry);
 79         mutex_unlock(&d_inode(parent)->i_mutex);
 80 }
 81 
 82 static void hypfs_delete_tree(struct dentry *root)
 83 {
 84         while (hypfs_last_dentry) {
 85                 struct dentry *next_dentry;
 86                 next_dentry = hypfs_last_dentry->d_fsdata;
 87                 hypfs_remove(hypfs_last_dentry);
 88                 hypfs_last_dentry = next_dentry;
 89         }
 90 }
 91 
 92 static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
 93 {
 94         struct inode *ret = new_inode(sb);
 95 
 96         if (ret) {
 97                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 98                 ret->i_ino = get_next_ino();
 99                 ret->i_mode = mode;
100                 ret->i_uid = hypfs_info->uid;
101                 ret->i_gid = hypfs_info->gid;
102                 ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
103                 if (S_ISDIR(mode))
104                         set_nlink(ret, 2);
105         }
106         return ret;
107 }
108 
109 static void hypfs_evict_inode(struct inode *inode)
110 {
111         clear_inode(inode);
112         kfree(inode->i_private);
113 }
114 
115 static int hypfs_open(struct inode *inode, struct file *filp)
116 {
117         char *data = file_inode(filp)->i_private;
118         struct hypfs_sb_info *fs_info;
119 
120         if (filp->f_mode & FMODE_WRITE) {
121                 if (!(inode->i_mode & S_IWUGO))
122                         return -EACCES;
123         }
124         if (filp->f_mode & FMODE_READ) {
125                 if (!(inode->i_mode & S_IRUGO))
126                         return -EACCES;
127         }
128 
129         fs_info = inode->i_sb->s_fs_info;
130         if(data) {
131                 mutex_lock(&fs_info->lock);
132                 filp->private_data = kstrdup(data, GFP_KERNEL);
133                 if (!filp->private_data) {
134                         mutex_unlock(&fs_info->lock);
135                         return -ENOMEM;
136                 }
137                 mutex_unlock(&fs_info->lock);
138         }
139         return nonseekable_open(inode, filp);
140 }
141 
142 static ssize_t hypfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
143 {
144         struct file *file = iocb->ki_filp;
145         char *data = file->private_data;
146         size_t available = strlen(data);
147         loff_t pos = iocb->ki_pos;
148         size_t count;
149 
150         if (pos < 0)
151                 return -EINVAL;
152         if (pos >= available || !iov_iter_count(to))
153                 return 0;
154         count = copy_to_iter(data + pos, available - pos, to);
155         if (!count)
156                 return -EFAULT;
157         iocb->ki_pos = pos + count;
158         file_accessed(file);
159         return count;
160 }
161 
162 static ssize_t hypfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
163 {
164         int rc;
165         struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
166         struct hypfs_sb_info *fs_info = sb->s_fs_info;
167         size_t count = iov_iter_count(from);
168 
169         /*
170          * Currently we only allow one update per second for two reasons:
171          * 1. diag 204 is VERY expensive
172          * 2. If several processes do updates in parallel and then read the
173          *    hypfs data, the likelihood of collisions is reduced, if we restrict
174          *    the minimum update interval. A collision occurs, if during the
175          *    data gathering of one process another process triggers an update
176          *    If the first process wants to ensure consistent data, it has
177          *    to restart data collection in this case.
178          */
179         mutex_lock(&fs_info->lock);
180         if (fs_info->last_update == get_seconds()) {
181                 rc = -EBUSY;
182                 goto out;
183         }
184         hypfs_delete_tree(sb->s_root);
185         if (MACHINE_IS_VM)
186                 rc = hypfs_vm_create_files(sb->s_root);
187         else
188                 rc = hypfs_diag_create_files(sb->s_root);
189         if (rc) {
190                 pr_err("Updating the hypfs tree failed\n");
191                 hypfs_delete_tree(sb->s_root);
192                 goto out;
193         }
194         hypfs_update_update(sb);
195         rc = count;
196         iov_iter_advance(from, count);
197 out:
198         mutex_unlock(&fs_info->lock);
199         return rc;
200 }
201 
202 static int hypfs_release(struct inode *inode, struct file *filp)
203 {
204         kfree(filp->private_data);
205         return 0;
206 }
207 
208 enum { opt_uid, opt_gid, opt_err };
209 
210 static const match_table_t hypfs_tokens = {
211         {opt_uid, "uid=%u"},
212         {opt_gid, "gid=%u"},
213         {opt_err, NULL}
214 };
215 
216 static int hypfs_parse_options(char *options, struct super_block *sb)
217 {
218         char *str;
219         substring_t args[MAX_OPT_ARGS];
220         kuid_t uid;
221         kgid_t gid;
222 
223         if (!options)
224                 return 0;
225         while ((str = strsep(&options, ",")) != NULL) {
226                 int token, option;
227                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
228 
229                 if (!*str)
230                         continue;
231                 token = match_token(str, hypfs_tokens, args);
232                 switch (token) {
233                 case opt_uid:
234                         if (match_int(&args[0], &option))
235                                 return -EINVAL;
236                         uid = make_kuid(current_user_ns(), option);
237                         if (!uid_valid(uid))
238                                 return -EINVAL;
239                         hypfs_info->uid = uid;
240                         break;
241                 case opt_gid:
242                         if (match_int(&args[0], &option))
243                                 return -EINVAL;
244                         gid = make_kgid(current_user_ns(), option);
245                         if (!gid_valid(gid))
246                                 return -EINVAL;
247                         hypfs_info->gid = gid;
248                         break;
249                 case opt_err:
250                 default:
251                         pr_err("%s is not a valid mount option\n", str);
252                         return -EINVAL;
253                 }
254         }
255         return 0;
256 }
257 
258 static int hypfs_show_options(struct seq_file *s, struct dentry *root)
259 {
260         struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;
261 
262         seq_printf(s, ",uid=%u", from_kuid_munged(&init_user_ns, hypfs_info->uid));
263         seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, hypfs_info->gid));
264         return 0;
265 }
266 
267 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
268 {
269         struct inode *root_inode;
270         struct dentry *root_dentry;
271         int rc = 0;
272         struct hypfs_sb_info *sbi;
273 
274         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
275         if (!sbi)
276                 return -ENOMEM;
277         mutex_init(&sbi->lock);
278         sbi->uid = current_uid();
279         sbi->gid = current_gid();
280         sb->s_fs_info = sbi;
281         sb->s_blocksize = PAGE_CACHE_SIZE;
282         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
283         sb->s_magic = HYPFS_MAGIC;
284         sb->s_op = &hypfs_s_ops;
285         if (hypfs_parse_options(data, sb))
286                 return -EINVAL;
287         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
288         if (!root_inode)
289                 return -ENOMEM;
290         root_inode->i_op = &simple_dir_inode_operations;
291         root_inode->i_fop = &simple_dir_operations;
292         sb->s_root = root_dentry = d_make_root(root_inode);
293         if (!root_dentry)
294                 return -ENOMEM;
295         if (MACHINE_IS_VM)
296                 rc = hypfs_vm_create_files(root_dentry);
297         else
298                 rc = hypfs_diag_create_files(root_dentry);
299         if (rc)
300                 return rc;
301         sbi->update_file = hypfs_create_update_file(root_dentry);
302         if (IS_ERR(sbi->update_file))
303                 return PTR_ERR(sbi->update_file);
304         hypfs_update_update(sb);
305         pr_info("Hypervisor filesystem mounted\n");
306         return 0;
307 }
308 
309 static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
310                         const char *devname, void *data)
311 {
312         return mount_single(fst, flags, data, hypfs_fill_super);
313 }
314 
315 static void hypfs_kill_super(struct super_block *sb)
316 {
317         struct hypfs_sb_info *sb_info = sb->s_fs_info;
318 
319         if (sb->s_root)
320                 hypfs_delete_tree(sb->s_root);
321         if (sb_info->update_file)
322                 hypfs_remove(sb_info->update_file);
323         kfree(sb->s_fs_info);
324         sb->s_fs_info = NULL;
325         kill_litter_super(sb);
326 }
327 
328 static struct dentry *hypfs_create_file(struct dentry *parent, const char *name,
329                                         char *data, umode_t mode)
330 {
331         struct dentry *dentry;
332         struct inode *inode;
333 
334         mutex_lock(&d_inode(parent)->i_mutex);
335         dentry = lookup_one_len(name, parent, strlen(name));
336         if (IS_ERR(dentry)) {
337                 dentry = ERR_PTR(-ENOMEM);
338                 goto fail;
339         }
340         inode = hypfs_make_inode(parent->d_sb, mode);
341         if (!inode) {
342                 dput(dentry);
343                 dentry = ERR_PTR(-ENOMEM);
344                 goto fail;
345         }
346         if (S_ISREG(mode)) {
347                 inode->i_fop = &hypfs_file_ops;
348                 if (data)
349                         inode->i_size = strlen(data);
350                 else
351                         inode->i_size = 0;
352         } else if (S_ISDIR(mode)) {
353                 inode->i_op = &simple_dir_inode_operations;
354                 inode->i_fop = &simple_dir_operations;
355                 inc_nlink(d_inode(parent));
356         } else
357                 BUG();
358         inode->i_private = data;
359         d_instantiate(dentry, inode);
360         dget(dentry);
361 fail:
362         mutex_unlock(&d_inode(parent)->i_mutex);
363         return dentry;
364 }
365 
366 struct dentry *hypfs_mkdir(struct dentry *parent, const char *name)
367 {
368         struct dentry *dentry;
369 
370         dentry = hypfs_create_file(parent, name, NULL, S_IFDIR | DIR_MODE);
371         if (IS_ERR(dentry))
372                 return dentry;
373         hypfs_add_dentry(dentry);
374         return dentry;
375 }
376 
377 static struct dentry *hypfs_create_update_file(struct dentry *dir)
378 {
379         struct dentry *dentry;
380 
381         dentry = hypfs_create_file(dir, "update", NULL,
382                                    S_IFREG | UPDATE_FILE_MODE);
383         /*
384          * We do not put the update file on the 'delete' list with
385          * hypfs_add_dentry(), since it should not be removed when the tree
386          * is updated.
387          */
388         return dentry;
389 }
390 
391 struct dentry *hypfs_create_u64(struct dentry *dir,
392                                 const char *name, __u64 value)
393 {
394         char *buffer;
395         char tmp[TMP_SIZE];
396         struct dentry *dentry;
397 
398         snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
399         buffer = kstrdup(tmp, GFP_KERNEL);
400         if (!buffer)
401                 return ERR_PTR(-ENOMEM);
402         dentry =
403             hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
404         if (IS_ERR(dentry)) {
405                 kfree(buffer);
406                 return ERR_PTR(-ENOMEM);
407         }
408         hypfs_add_dentry(dentry);
409         return dentry;
410 }
411 
412 struct dentry *hypfs_create_str(struct dentry *dir,
413                                 const char *name, char *string)
414 {
415         char *buffer;
416         struct dentry *dentry;
417 
418         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
419         if (!buffer)
420                 return ERR_PTR(-ENOMEM);
421         sprintf(buffer, "%s\n", string);
422         dentry =
423             hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
424         if (IS_ERR(dentry)) {
425                 kfree(buffer);
426                 return ERR_PTR(-ENOMEM);
427         }
428         hypfs_add_dentry(dentry);
429         return dentry;
430 }
431 
432 static const struct file_operations hypfs_file_ops = {
433         .open           = hypfs_open,
434         .release        = hypfs_release,
435         .read_iter      = hypfs_read_iter,
436         .write_iter     = hypfs_write_iter,
437         .llseek         = no_llseek,
438 };
439 
440 static struct file_system_type hypfs_type = {
441         .owner          = THIS_MODULE,
442         .name           = "s390_hypfs",
443         .mount          = hypfs_mount,
444         .kill_sb        = hypfs_kill_super
445 };
446 MODULE_ALIAS_FS("s390_hypfs");
447 
448 static const struct super_operations hypfs_s_ops = {
449         .statfs         = simple_statfs,
450         .evict_inode    = hypfs_evict_inode,
451         .show_options   = hypfs_show_options,
452 };
453 
454 static int __init hypfs_init(void)
455 {
456         int rc;
457 
458         rc = hypfs_dbfs_init();
459         if (rc)
460                 return rc;
461         if (hypfs_diag_init()) {
462                 rc = -ENODATA;
463                 goto fail_dbfs_exit;
464         }
465         if (hypfs_vm_init()) {
466                 rc = -ENODATA;
467                 goto fail_hypfs_diag_exit;
468         }
469         if (hypfs_sprp_init()) {
470                 rc = -ENODATA;
471                 goto fail_hypfs_vm_exit;
472         }
473         if (hypfs_diag0c_init()) {
474                 rc = -ENODATA;
475                 goto fail_hypfs_sprp_exit;
476         }
477         rc = sysfs_create_mount_point(hypervisor_kobj, "s390");
478         if (rc)
479                 goto fail_hypfs_diag0c_exit;
480         rc = register_filesystem(&hypfs_type);
481         if (rc)
482                 goto fail_filesystem;
483         return 0;
484 
485 fail_filesystem:
486         sysfs_remove_mount_point(hypervisor_kobj, "s390");
487 fail_hypfs_diag0c_exit:
488         hypfs_diag0c_exit();
489 fail_hypfs_sprp_exit:
490         hypfs_sprp_exit();
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         unregister_filesystem(&hypfs_type);
504         sysfs_remove_mount_point(hypervisor_kobj, "s390");
505         hypfs_diag0c_exit();
506         hypfs_sprp_exit();
507         hypfs_vm_exit();
508         hypfs_diag_exit();
509         hypfs_dbfs_exit();
510 }
511 
512 module_init(hypfs_init)
513 module_exit(hypfs_exit)
514 
515 MODULE_LICENSE("GPL");
516 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
517 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");
518 

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