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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  *    License: GPL
  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/init.h>
 23 #include <linux/kobject.h>
 24 #include <linux/seq_file.h>
 25 #include <linux/mount.h>
 26 #include <linux/uio.h>
 27 #include <asm/ebcdic.h>
 28 #include "hypfs.h"
 29 
 30 #define HYPFS_MAGIC 0x687970    /* ASCII 'hyp' */
 31 #define TMP_SIZE 64             /* size of temporary buffers */
 32 
 33 static struct dentry *hypfs_create_update_file(struct dentry *dir);
 34 
 35 struct hypfs_sb_info {
 36         kuid_t uid;                     /* uid used for files and dirs */
 37         kgid_t gid;                     /* gid used for files and dirs */
 38         struct dentry *update_file;     /* file to trigger update */
 39         time_t last_update;             /* last update time in secs since 1970 */
 40         struct mutex lock;              /* lock to protect update process */
 41 };
 42 
 43 static const struct file_operations hypfs_file_ops;
 44 static struct file_system_type hypfs_type;
 45 static const struct super_operations hypfs_s_ops;
 46 
 47 /* start of list of all dentries, which have to be deleted on update */
 48 static struct dentry *hypfs_last_dentry;
 49 
 50 static void hypfs_update_update(struct super_block *sb)
 51 {
 52         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 53         struct inode *inode = d_inode(sb_info->update_file);
 54 
 55         sb_info->last_update = get_seconds();
 56         inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 57 }
 58 
 59 /* directory tree removal functions */
 60 
 61 static void hypfs_add_dentry(struct dentry *dentry)
 62 {
 63         dentry->d_fsdata = hypfs_last_dentry;
 64         hypfs_last_dentry = dentry;
 65 }
 66 
 67 static void hypfs_remove(struct dentry *dentry)
 68 {
 69         struct dentry *parent;
 70 
 71         parent = dentry->d_parent;
 72         inode_lock(d_inode(parent));
 73         if (simple_positive(dentry)) {
 74                 if (d_is_dir(dentry))
 75                         simple_rmdir(d_inode(parent), dentry);
 76                 else
 77                         simple_unlink(d_inode(parent), dentry);
 78         }
 79         d_delete(dentry);
 80         dput(dentry);
 81         inode_unlock(d_inode(parent));
 82 }
 83 
 84 static void hypfs_delete_tree(struct dentry *root)
 85 {
 86         while (hypfs_last_dentry) {
 87                 struct dentry *next_dentry;
 88                 next_dentry = hypfs_last_dentry->d_fsdata;
 89                 hypfs_remove(hypfs_last_dentry);
 90                 hypfs_last_dentry = next_dentry;
 91         }
 92 }
 93 
 94 static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
 95 {
 96         struct inode *ret = new_inode(sb);
 97 
 98         if (ret) {
 99                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
100                 ret->i_ino = get_next_ino();
101                 ret->i_mode = mode;
102                 ret->i_uid = hypfs_info->uid;
103                 ret->i_gid = hypfs_info->gid;
104                 ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(ret);
105                 if (S_ISDIR(mode))
106                         set_nlink(ret, 2);
107         }
108         return ret;
109 }
110 
111 static void hypfs_evict_inode(struct inode *inode)
112 {
113         clear_inode(inode);
114         kfree(inode->i_private);
115 }
116 
117 static int hypfs_open(struct inode *inode, struct file *filp)
118 {
119         char *data = file_inode(filp)->i_private;
120         struct hypfs_sb_info *fs_info;
121 
122         if (filp->f_mode & FMODE_WRITE) {
123                 if (!(inode->i_mode & S_IWUGO))
124                         return -EACCES;
125         }
126         if (filp->f_mode & FMODE_READ) {
127                 if (!(inode->i_mode & S_IRUGO))
128                         return -EACCES;
129         }
130 
131         fs_info = inode->i_sb->s_fs_info;
132         if(data) {
133                 mutex_lock(&fs_info->lock);
134                 filp->private_data = kstrdup(data, GFP_KERNEL);
135                 if (!filp->private_data) {
136                         mutex_unlock(&fs_info->lock);
137                         return -ENOMEM;
138                 }
139                 mutex_unlock(&fs_info->lock);
140         }
141         return nonseekable_open(inode, filp);
142 }
143 
144 static ssize_t hypfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
145 {
146         struct file *file = iocb->ki_filp;
147         char *data = file->private_data;
148         size_t available = strlen(data);
149         loff_t pos = iocb->ki_pos;
150         size_t count;
151 
152         if (pos < 0)
153                 return -EINVAL;
154         if (pos >= available || !iov_iter_count(to))
155                 return 0;
156         count = copy_to_iter(data + pos, available - pos, to);
157         if (!count)
158                 return -EFAULT;
159         iocb->ki_pos = pos + count;
160         file_accessed(file);
161         return count;
162 }
163 
164 static ssize_t hypfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
165 {
166         int rc;
167         struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
168         struct hypfs_sb_info *fs_info = sb->s_fs_info;
169         size_t count = iov_iter_count(from);
170 
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         if (MACHINE_IS_VM)
188                 rc = hypfs_vm_create_files(sb->s_root);
189         else
190                 rc = hypfs_diag_create_files(sb->s_root);
191         if (rc) {
192                 pr_err("Updating the hypfs tree failed\n");
193                 hypfs_delete_tree(sb->s_root);
194                 goto out;
195         }
196         hypfs_update_update(sb);
197         rc = count;
198         iov_iter_advance(from, count);
199 out:
200         mutex_unlock(&fs_info->lock);
201         return rc;
202 }
203 
204 static int hypfs_release(struct inode *inode, struct file *filp)
205 {
206         kfree(filp->private_data);
207         return 0;
208 }
209 
210 enum { opt_uid, opt_gid, opt_err };
211 
212 static const match_table_t hypfs_tokens = {
213         {opt_uid, "uid=%u"},
214         {opt_gid, "gid=%u"},
215         {opt_err, NULL}
216 };
217 
218 static int hypfs_parse_options(char *options, struct super_block *sb)
219 {
220         char *str;
221         substring_t args[MAX_OPT_ARGS];
222         kuid_t uid;
223         kgid_t gid;
224 
225         if (!options)
226                 return 0;
227         while ((str = strsep(&options, ",")) != NULL) {
228                 int token, option;
229                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
230 
231                 if (!*str)
232                         continue;
233                 token = match_token(str, hypfs_tokens, args);
234                 switch (token) {
235                 case opt_uid:
236                         if (match_int(&args[0], &option))
237                                 return -EINVAL;
238                         uid = make_kuid(current_user_ns(), option);
239                         if (!uid_valid(uid))
240                                 return -EINVAL;
241                         hypfs_info->uid = uid;
242                         break;
243                 case opt_gid:
244                         if (match_int(&args[0], &option))
245                                 return -EINVAL;
246                         gid = make_kgid(current_user_ns(), option);
247                         if (!gid_valid(gid))
248                                 return -EINVAL;
249                         hypfs_info->gid = gid;
250                         break;
251                 case opt_err:
252                 default:
253                         pr_err("%s is not a valid mount option\n", str);
254                         return -EINVAL;
255                 }
256         }
257         return 0;
258 }
259 
260 static int hypfs_show_options(struct seq_file *s, struct dentry *root)
261 {
262         struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;
263 
264         seq_printf(s, ",uid=%u", from_kuid_munged(&init_user_ns, hypfs_info->uid));
265         seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, hypfs_info->gid));
266         return 0;
267 }
268 
269 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
270 {
271         struct inode *root_inode;
272         struct dentry *root_dentry;
273         int rc = 0;
274         struct hypfs_sb_info *sbi;
275 
276         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
277         if (!sbi)
278                 return -ENOMEM;
279         mutex_init(&sbi->lock);
280         sbi->uid = current_uid();
281         sbi->gid = current_gid();
282         sb->s_fs_info = sbi;
283         sb->s_blocksize = PAGE_SIZE;
284         sb->s_blocksize_bits = PAGE_SHIFT;
285         sb->s_magic = HYPFS_MAGIC;
286         sb->s_op = &hypfs_s_ops;
287         if (hypfs_parse_options(data, sb))
288                 return -EINVAL;
289         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
290         if (!root_inode)
291                 return -ENOMEM;
292         root_inode->i_op = &simple_dir_inode_operations;
293         root_inode->i_fop = &simple_dir_operations;
294         sb->s_root = root_dentry = d_make_root(root_inode);
295         if (!root_dentry)
296                 return -ENOMEM;
297         if (MACHINE_IS_VM)
298                 rc = hypfs_vm_create_files(root_dentry);
299         else
300                 rc = hypfs_diag_create_files(root_dentry);
301         if (rc)
302                 return rc;
303         sbi->update_file = hypfs_create_update_file(root_dentry);
304         if (IS_ERR(sbi->update_file))
305                 return PTR_ERR(sbi->update_file);
306         hypfs_update_update(sb);
307         pr_info("Hypervisor filesystem mounted\n");
308         return 0;
309 }
310 
311 static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
312                         const char *devname, void *data)
313 {
314         return mount_single(fst, flags, data, hypfs_fill_super);
315 }
316 
317 static void hypfs_kill_super(struct super_block *sb)
318 {
319         struct hypfs_sb_info *sb_info = sb->s_fs_info;
320 
321         if (sb->s_root)
322                 hypfs_delete_tree(sb->s_root);
323         if (sb_info->update_file)
324                 hypfs_remove(sb_info->update_file);
325         kfree(sb->s_fs_info);
326         sb->s_fs_info = NULL;
327         kill_litter_super(sb);
328 }
329 
330 static struct dentry *hypfs_create_file(struct dentry *parent, const char *name,
331                                         char *data, umode_t mode)
332 {
333         struct dentry *dentry;
334         struct inode *inode;
335 
336         inode_lock(d_inode(parent));
337         dentry = lookup_one_len(name, parent, strlen(name));
338         if (IS_ERR(dentry)) {
339                 dentry = ERR_PTR(-ENOMEM);
340                 goto fail;
341         }
342         inode = hypfs_make_inode(parent->d_sb, mode);
343         if (!inode) {
344                 dput(dentry);
345                 dentry = ERR_PTR(-ENOMEM);
346                 goto fail;
347         }
348         if (S_ISREG(mode)) {
349                 inode->i_fop = &hypfs_file_ops;
350                 if (data)
351                         inode->i_size = strlen(data);
352                 else
353                         inode->i_size = 0;
354         } else if (S_ISDIR(mode)) {
355                 inode->i_op = &simple_dir_inode_operations;
356                 inode->i_fop = &simple_dir_operations;
357                 inc_nlink(d_inode(parent));
358         } else
359                 BUG();
360         inode->i_private = data;
361         d_instantiate(dentry, inode);
362         dget(dentry);
363 fail:
364         inode_unlock(d_inode(parent));
365         return dentry;
366 }
367 
368 struct dentry *hypfs_mkdir(struct dentry *parent, const char *name)
369 {
370         struct dentry *dentry;
371 
372         dentry = hypfs_create_file(parent, name, NULL, S_IFDIR | DIR_MODE);
373         if (IS_ERR(dentry))
374                 return dentry;
375         hypfs_add_dentry(dentry);
376         return dentry;
377 }
378 
379 static struct dentry *hypfs_create_update_file(struct dentry *dir)
380 {
381         struct dentry *dentry;
382 
383         dentry = hypfs_create_file(dir, "update", NULL,
384                                    S_IFREG | UPDATE_FILE_MODE);
385         /*
386          * We do not put the update file on the 'delete' list with
387          * hypfs_add_dentry(), since it should not be removed when the tree
388          * is updated.
389          */
390         return dentry;
391 }
392 
393 struct dentry *hypfs_create_u64(struct dentry *dir,
394                                 const char *name, __u64 value)
395 {
396         char *buffer;
397         char tmp[TMP_SIZE];
398         struct dentry *dentry;
399 
400         snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
401         buffer = kstrdup(tmp, GFP_KERNEL);
402         if (!buffer)
403                 return ERR_PTR(-ENOMEM);
404         dentry =
405             hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
406         if (IS_ERR(dentry)) {
407                 kfree(buffer);
408                 return ERR_PTR(-ENOMEM);
409         }
410         hypfs_add_dentry(dentry);
411         return dentry;
412 }
413 
414 struct dentry *hypfs_create_str(struct dentry *dir,
415                                 const char *name, char *string)
416 {
417         char *buffer;
418         struct dentry *dentry;
419 
420         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
421         if (!buffer)
422                 return ERR_PTR(-ENOMEM);
423         sprintf(buffer, "%s\n", string);
424         dentry =
425             hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
426         if (IS_ERR(dentry)) {
427                 kfree(buffer);
428                 return ERR_PTR(-ENOMEM);
429         }
430         hypfs_add_dentry(dentry);
431         return dentry;
432 }
433 
434 static const struct file_operations hypfs_file_ops = {
435         .open           = hypfs_open,
436         .release        = hypfs_release,
437         .read_iter      = hypfs_read_iter,
438         .write_iter     = hypfs_write_iter,
439         .llseek         = no_llseek,
440 };
441 
442 static struct file_system_type hypfs_type = {
443         .owner          = THIS_MODULE,
444         .name           = "s390_hypfs",
445         .mount          = hypfs_mount,
446         .kill_sb        = hypfs_kill_super
447 };
448 
449 static const struct super_operations hypfs_s_ops = {
450         .statfs         = simple_statfs,
451         .evict_inode    = hypfs_evict_inode,
452         .show_options   = hypfs_show_options,
453 };
454 
455 static int __init hypfs_init(void)
456 {
457         int rc;
458 
459         rc = hypfs_dbfs_init();
460         if (rc)
461                 return rc;
462         if (hypfs_diag_init()) {
463                 rc = -ENODATA;
464                 goto fail_dbfs_exit;
465         }
466         if (hypfs_vm_init()) {
467                 rc = -ENODATA;
468                 goto fail_hypfs_diag_exit;
469         }
470         if (hypfs_sprp_init()) {
471                 rc = -ENODATA;
472                 goto fail_hypfs_vm_exit;
473         }
474         if (hypfs_diag0c_init()) {
475                 rc = -ENODATA;
476                 goto fail_hypfs_sprp_exit;
477         }
478         rc = sysfs_create_mount_point(hypervisor_kobj, "s390");
479         if (rc)
480                 goto fail_hypfs_diag0c_exit;
481         rc = register_filesystem(&hypfs_type);
482         if (rc)
483                 goto fail_filesystem;
484         return 0;
485 
486 fail_filesystem:
487         sysfs_remove_mount_point(hypervisor_kobj, "s390");
488 fail_hypfs_diag0c_exit:
489         hypfs_diag0c_exit();
490 fail_hypfs_sprp_exit:
491         hypfs_sprp_exit();
492 fail_hypfs_vm_exit:
493         hypfs_vm_exit();
494 fail_hypfs_diag_exit:
495         hypfs_diag_exit();
496 fail_dbfs_exit:
497         hypfs_dbfs_exit();
498         pr_err("Initialization of hypfs failed with rc=%i\n", rc);
499         return rc;
500 }
501 device_initcall(hypfs_init)
502 

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