1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * dlmfs.c
4 *
5 * Code which implements the kernel side of a minimal userspace
6 * interface to our DLM. This file handles the virtual file system
7 * used for communication with userspace. Credit should go to ramfs,
8 * which was a template for the fs side of this module.
9 *
10 * Copyright (C) 2003, 2004 Oracle. All rights reserved.
11 */
12
13 /* Simple VFS hooks based on: */
14 /*
15 * Resizable simple ram filesystem for Linux.
16 *
17 * Copyright (C) 2000 Linus Torvalds.
18 * 2000 Transmeta Corp.
19 */
20
21 #include <linux/module.h>
22 #include <linux/fs.h>
23 #include <linux/pagemap.h>
24 #include <linux/types.h>
25 #include <linux/slab.h>
26 #include <linux/highmem.h>
27 #include <linux/init.h>
28 #include <linux/string.h>
29 #include <linux/backing-dev.h>
30 #include <linux/poll.h>
31
32 #include <linux/uaccess.h>
33
34 #include "../stackglue.h"
35 #include "userdlm.h"
36
37 #define MLOG_MASK_PREFIX ML_DLMFS
38 #include "../cluster/masklog.h"
39
40
41 static const struct super_operations dlmfs_ops;
42 static const struct file_operations dlmfs_file_operations;
43 static const struct inode_operations dlmfs_dir_inode_operations;
44 static const struct inode_operations dlmfs_root_inode_operations;
45 static const struct inode_operations dlmfs_file_inode_operations;
46 static struct kmem_cache *dlmfs_inode_cache;
47
48 struct workqueue_struct *user_dlm_worker;
49
50
51
52 /*
53 * These are the ABI capabilities of dlmfs.
54 *
55 * Over time, dlmfs has added some features that were not part of the
56 * initial ABI. Unfortunately, some of these features are not detectable
57 * via standard usage. For example, Linux's default poll always returns
58 * EPOLLIN, so there is no way for a caller of poll(2) to know when dlmfs
59 * added poll support. Instead, we provide this list of new capabilities.
60 *
61 * Capabilities is a read-only attribute. We do it as a module parameter
62 * so we can discover it whether dlmfs is built in, loaded, or even not
63 * loaded.
64 *
65 * The ABI features are local to this machine's dlmfs mount. This is
66 * distinct from the locking protocol, which is concerned with inter-node
67 * interaction.
68 *
69 * Capabilities:
70 * - bast : EPOLLIN against the file descriptor of a held lock
71 * signifies a bast fired on the lock.
72 */
73 #define DLMFS_CAPABILITIES "bast stackglue"
74 static int param_set_dlmfs_capabilities(const char *val,
75 const struct kernel_param *kp)
76 {
77 printk(KERN_ERR "%s: readonly parameter\n", kp->name);
78 return -EINVAL;
79 }
80 static int param_get_dlmfs_capabilities(char *buffer,
81 const struct kernel_param *kp)
82 {
83 return sysfs_emit(buffer, DLMFS_CAPABILITIES);
84 }
85 module_param_call(capabilities, param_set_dlmfs_capabilities,
86 param_get_dlmfs_capabilities, NULL, 0444);
87 MODULE_PARM_DESC(capabilities, DLMFS_CAPABILITIES);
88
89
90 /*
91 * decodes a set of open flags into a valid lock level and a set of flags.
92 * returns < 0 if we have invalid flags
93 * flags which mean something to us:
94 * O_RDONLY -> PRMODE level
95 * O_WRONLY -> EXMODE level
96 *
97 * O_NONBLOCK -> NOQUEUE
98 */
99 static int dlmfs_decode_open_flags(int open_flags,
100 int *level,
101 int *flags)
102 {
103 if (open_flags & (O_WRONLY|O_RDWR))
104 *level = DLM_LOCK_EX;
105 else
106 *level = DLM_LOCK_PR;
107
108 *flags = 0;
109 if (open_flags & O_NONBLOCK)
110 *flags |= DLM_LKF_NOQUEUE;
111
112 return 0;
113 }
114
115 static int dlmfs_file_open(struct inode *inode,
116 struct file *file)
117 {
118 int status, level, flags;
119 struct dlmfs_filp_private *fp = NULL;
120 struct dlmfs_inode_private *ip;
121
122 if (S_ISDIR(inode->i_mode))
123 BUG();
124
125 mlog(0, "open called on inode %lu, flags 0x%x\n", inode->i_ino,
126 file->f_flags);
127
128 status = dlmfs_decode_open_flags(file->f_flags, &level, &flags);
129 if (status < 0)
130 goto bail;
131
132 /* We don't want to honor O_APPEND at read/write time as it
133 * doesn't make sense for LVB writes. */
134 file->f_flags &= ~O_APPEND;
135
136 fp = kmalloc(sizeof(*fp), GFP_NOFS);
137 if (!fp) {
138 status = -ENOMEM;
139 goto bail;
140 }
141 fp->fp_lock_level = level;
142
143 ip = DLMFS_I(inode);
144
145 status = user_dlm_cluster_lock(&ip->ip_lockres, level, flags);
146 if (status < 0) {
147 /* this is a strange error to return here but I want
148 * to be able userspace to be able to distinguish a
149 * valid lock request from one that simply couldn't be
150 * granted. */
151 if (flags & DLM_LKF_NOQUEUE && status == -EAGAIN)
152 status = -ETXTBSY;
153 kfree(fp);
154 goto bail;
155 }
156
157 file->private_data = fp;
158 bail:
159 return status;
160 }
161
162 static int dlmfs_file_release(struct inode *inode,
163 struct file *file)
164 {
165 int level;
166 struct dlmfs_inode_private *ip = DLMFS_I(inode);
167 struct dlmfs_filp_private *fp = file->private_data;
168
169 if (S_ISDIR(inode->i_mode))
170 BUG();
171
172 mlog(0, "close called on inode %lu\n", inode->i_ino);
173
174 if (fp) {
175 level = fp->fp_lock_level;
176 if (level != DLM_LOCK_IV)
177 user_dlm_cluster_unlock(&ip->ip_lockres, level);
178
179 kfree(fp);
180 file->private_data = NULL;
181 }
182
183 return 0;
184 }
185
186 /*
187 * We do ->setattr() just to override size changes. Our size is the size
188 * of the LVB and nothing else.
189 */
190 static int dlmfs_file_setattr(struct mnt_idmap *idmap,
191 struct dentry *dentry, struct iattr *attr)
192 {
193 int error;
194 struct inode *inode = d_inode(dentry);
195
196 attr->ia_valid &= ~ATTR_SIZE;
197 error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
198 if (error)
199 return error;
200
201 setattr_copy(&nop_mnt_idmap, inode, attr);
202 mark_inode_dirty(inode);
203 return 0;
204 }
205
206 static __poll_t dlmfs_file_poll(struct file *file, poll_table *wait)
207 {
208 __poll_t event = 0;
209 struct inode *inode = file_inode(file);
210 struct dlmfs_inode_private *ip = DLMFS_I(inode);
211
212 poll_wait(file, &ip->ip_lockres.l_event, wait);
213
214 spin_lock(&ip->ip_lockres.l_lock);
215 if (ip->ip_lockres.l_flags & USER_LOCK_BLOCKED)
216 event = EPOLLIN | EPOLLRDNORM;
217 spin_unlock(&ip->ip_lockres.l_lock);
218
219 return event;
220 }
221
222 static ssize_t dlmfs_file_read(struct file *file,
223 char __user *buf,
224 size_t count,
225 loff_t *ppos)
226 {
227 char lvb[DLM_LVB_LEN];
228
229 if (!user_dlm_read_lvb(file_inode(file), lvb))
230 return 0;
231
232 return simple_read_from_buffer(buf, count, ppos, lvb, sizeof(lvb));
233 }
234
235 static ssize_t dlmfs_file_write(struct file *filp,
236 const char __user *buf,
237 size_t count,
238 loff_t *ppos)
239 {
240 char lvb_buf[DLM_LVB_LEN];
241 int bytes_left;
242 struct inode *inode = file_inode(filp);
243
244 mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
245 inode->i_ino, count, *ppos);
246
247 if (*ppos >= DLM_LVB_LEN)
248 return -ENOSPC;
249
250 /* don't write past the lvb */
251 if (count > DLM_LVB_LEN - *ppos)
252 count = DLM_LVB_LEN - *ppos;
253
254 if (!count)
255 return 0;
256
257 bytes_left = copy_from_user(lvb_buf, buf, count);
258 count -= bytes_left;
259 if (count)
260 user_dlm_write_lvb(inode, lvb_buf, count);
261
262 *ppos = *ppos + count;
263 mlog(0, "wrote %zu bytes\n", count);
264 return count;
265 }
266
267 static void dlmfs_init_once(void *foo)
268 {
269 struct dlmfs_inode_private *ip =
270 (struct dlmfs_inode_private *) foo;
271
272 ip->ip_conn = NULL;
273 ip->ip_parent = NULL;
274
275 inode_init_once(&ip->ip_vfs_inode);
276 }
277
278 static struct inode *dlmfs_alloc_inode(struct super_block *sb)
279 {
280 struct dlmfs_inode_private *ip;
281
282 ip = alloc_inode_sb(sb, dlmfs_inode_cache, GFP_NOFS);
283 if (!ip)
284 return NULL;
285
286 return &ip->ip_vfs_inode;
287 }
288
289 static void dlmfs_free_inode(struct inode *inode)
290 {
291 kmem_cache_free(dlmfs_inode_cache, DLMFS_I(inode));
292 }
293
294 static void dlmfs_evict_inode(struct inode *inode)
295 {
296 int status;
297 struct dlmfs_inode_private *ip;
298 struct user_lock_res *lockres;
299 int teardown;
300
301 clear_inode(inode);
302
303 mlog(0, "inode %lu\n", inode->i_ino);
304
305 ip = DLMFS_I(inode);
306 lockres = &ip->ip_lockres;
307
308 if (S_ISREG(inode->i_mode)) {
309 spin_lock(&lockres->l_lock);
310 teardown = !!(lockres->l_flags & USER_LOCK_IN_TEARDOWN);
311 spin_unlock(&lockres->l_lock);
312 if (!teardown) {
313 status = user_dlm_destroy_lock(lockres);
314 if (status < 0)
315 mlog_errno(status);
316 }
317 iput(ip->ip_parent);
318 goto clear_fields;
319 }
320
321 mlog(0, "we're a directory, ip->ip_conn = 0x%p\n", ip->ip_conn);
322 /* we must be a directory. If required, lets unregister the
323 * dlm context now. */
324 if (ip->ip_conn)
325 user_dlm_unregister(ip->ip_conn);
326 clear_fields:
327 ip->ip_parent = NULL;
328 ip->ip_conn = NULL;
329 }
330
331 static struct inode *dlmfs_get_root_inode(struct super_block *sb)
332 {
333 struct inode *inode = new_inode(sb);
334 umode_t mode = S_IFDIR | 0755;
335
336 if (inode) {
337 inode->i_ino = get_next_ino();
338 inode_init_owner(&nop_mnt_idmap, inode, NULL, mode);
339 simple_inode_init_ts(inode);
340 inc_nlink(inode);
341
342 inode->i_fop = &simple_dir_operations;
343 inode->i_op = &dlmfs_root_inode_operations;
344 }
345
346 return inode;
347 }
348
349 static struct inode *dlmfs_get_inode(struct inode *parent,
350 struct dentry *dentry,
351 umode_t mode)
352 {
353 struct super_block *sb = parent->i_sb;
354 struct inode * inode = new_inode(sb);
355 struct dlmfs_inode_private *ip;
356
357 if (!inode)
358 return NULL;
359
360 inode->i_ino = get_next_ino();
361 inode_init_owner(&nop_mnt_idmap, inode, parent, mode);
362 simple_inode_init_ts(inode);
363
364 ip = DLMFS_I(inode);
365 ip->ip_conn = DLMFS_I(parent)->ip_conn;
366
367 switch (mode & S_IFMT) {
368 default:
369 /* for now we don't support anything other than
370 * directories and regular files. */
371 BUG();
372 break;
373 case S_IFREG:
374 inode->i_op = &dlmfs_file_inode_operations;
375 inode->i_fop = &dlmfs_file_operations;
376
377 i_size_write(inode, DLM_LVB_LEN);
378
379 user_dlm_lock_res_init(&ip->ip_lockres, dentry);
380
381 /* released at clear_inode time, this insures that we
382 * get to drop the dlm reference on each lock *before*
383 * we call the unregister code for releasing parent
384 * directories. */
385 ip->ip_parent = igrab(parent);
386 BUG_ON(!ip->ip_parent);
387 break;
388 case S_IFDIR:
389 inode->i_op = &dlmfs_dir_inode_operations;
390 inode->i_fop = &simple_dir_operations;
391
392 /* directory inodes start off with i_nlink ==
393 * 2 (for "." entry) */
394 inc_nlink(inode);
395 break;
396 }
397 return inode;
398 }
399
400 /*
401 * File creation. Allocate an inode, and we're done..
402 */
403 /* SMP-safe */
404 static int dlmfs_mkdir(struct mnt_idmap * idmap,
405 struct inode * dir,
406 struct dentry * dentry,
407 umode_t mode)
408 {
409 int status;
410 struct inode *inode = NULL;
411 const struct qstr *domain = &dentry->d_name;
412 struct dlmfs_inode_private *ip;
413 struct ocfs2_cluster_connection *conn;
414
415 mlog(0, "mkdir %.*s\n", domain->len, domain->name);
416
417 /* verify that we have a proper domain */
418 if (domain->len >= GROUP_NAME_MAX) {
419 status = -EINVAL;
420 mlog(ML_ERROR, "invalid domain name for directory.\n");
421 goto bail;
422 }
423
424 inode = dlmfs_get_inode(dir, dentry, mode | S_IFDIR);
425 if (!inode) {
426 status = -ENOMEM;
427 mlog_errno(status);
428 goto bail;
429 }
430
431 ip = DLMFS_I(inode);
432
433 conn = user_dlm_register(domain);
434 if (IS_ERR(conn)) {
435 status = PTR_ERR(conn);
436 mlog(ML_ERROR, "Error %d could not register domain \"%.*s\"\n",
437 status, domain->len, domain->name);
438 goto bail;
439 }
440 ip->ip_conn = conn;
441
442 inc_nlink(dir);
443 d_instantiate(dentry, inode);
444 dget(dentry); /* Extra count - pin the dentry in core */
445
446 status = 0;
447 bail:
448 if (status < 0)
449 iput(inode);
450 return status;
451 }
452
453 static int dlmfs_create(struct mnt_idmap *idmap,
454 struct inode *dir,
455 struct dentry *dentry,
456 umode_t mode,
457 bool excl)
458 {
459 int status = 0;
460 struct inode *inode;
461 const struct qstr *name = &dentry->d_name;
462
463 mlog(0, "create %.*s\n", name->len, name->name);
464
465 /* verify name is valid and doesn't contain any dlm reserved
466 * characters */
467 if (name->len >= USER_DLM_LOCK_ID_MAX_LEN ||
468 name->name[0] == '$') {
469 status = -EINVAL;
470 mlog(ML_ERROR, "invalid lock name, %.*s\n", name->len,
471 name->name);
472 goto bail;
473 }
474
475 inode = dlmfs_get_inode(dir, dentry, mode | S_IFREG);
476 if (!inode) {
477 status = -ENOMEM;
478 mlog_errno(status);
479 goto bail;
480 }
481
482 d_instantiate(dentry, inode);
483 dget(dentry); /* Extra count - pin the dentry in core */
484 bail:
485 return status;
486 }
487
488 static int dlmfs_unlink(struct inode *dir,
489 struct dentry *dentry)
490 {
491 int status;
492 struct inode *inode = d_inode(dentry);
493
494 mlog(0, "unlink inode %lu\n", inode->i_ino);
495
496 /* if there are no current holders, or none that are waiting
497 * to acquire a lock, this basically destroys our lockres. */
498 status = user_dlm_destroy_lock(&DLMFS_I(inode)->ip_lockres);
499 if (status < 0) {
500 mlog(ML_ERROR, "unlink %pd, error %d from destroy\n",
501 dentry, status);
502 goto bail;
503 }
504 status = simple_unlink(dir, dentry);
505 bail:
506 return status;
507 }
508
509 static int dlmfs_fill_super(struct super_block * sb,
510 void * data,
511 int silent)
512 {
513 sb->s_maxbytes = MAX_LFS_FILESIZE;
514 sb->s_blocksize = PAGE_SIZE;
515 sb->s_blocksize_bits = PAGE_SHIFT;
516 sb->s_magic = DLMFS_MAGIC;
517 sb->s_op = &dlmfs_ops;
518 sb->s_root = d_make_root(dlmfs_get_root_inode(sb));
519 if (!sb->s_root)
520 return -ENOMEM;
521 return 0;
522 }
523
524 static const struct file_operations dlmfs_file_operations = {
525 .open = dlmfs_file_open,
526 .release = dlmfs_file_release,
527 .poll = dlmfs_file_poll,
528 .read = dlmfs_file_read,
529 .write = dlmfs_file_write,
530 .llseek = default_llseek,
531 };
532
533 static const struct inode_operations dlmfs_dir_inode_operations = {
534 .create = dlmfs_create,
535 .lookup = simple_lookup,
536 .unlink = dlmfs_unlink,
537 };
538
539 /* this way we can restrict mkdir to only the toplevel of the fs. */
540 static const struct inode_operations dlmfs_root_inode_operations = {
541 .lookup = simple_lookup,
542 .mkdir = dlmfs_mkdir,
543 .rmdir = simple_rmdir,
544 };
545
546 static const struct super_operations dlmfs_ops = {
547 .statfs = simple_statfs,
548 .alloc_inode = dlmfs_alloc_inode,
549 .free_inode = dlmfs_free_inode,
550 .evict_inode = dlmfs_evict_inode,
551 .drop_inode = generic_delete_inode,
552 };
553
554 static const struct inode_operations dlmfs_file_inode_operations = {
555 .getattr = simple_getattr,
556 .setattr = dlmfs_file_setattr,
557 };
558
559 static struct dentry *dlmfs_mount(struct file_system_type *fs_type,
560 int flags, const char *dev_name, void *data)
561 {
562 return mount_nodev(fs_type, flags, data, dlmfs_fill_super);
563 }
564
565 static struct file_system_type dlmfs_fs_type = {
566 .owner = THIS_MODULE,
567 .name = "ocfs2_dlmfs",
568 .mount = dlmfs_mount,
569 .kill_sb = kill_litter_super,
570 };
571 MODULE_ALIAS_FS("ocfs2_dlmfs");
572
573 static int __init init_dlmfs_fs(void)
574 {
575 int status;
576 int cleanup_inode = 0, cleanup_worker = 0;
577
578 dlmfs_inode_cache = kmem_cache_create("dlmfs_inode_cache",
579 sizeof(struct dlmfs_inode_private),
580 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
581 SLAB_ACCOUNT),
582 dlmfs_init_once);
583 if (!dlmfs_inode_cache) {
584 status = -ENOMEM;
585 goto bail;
586 }
587 cleanup_inode = 1;
588
589 user_dlm_worker = alloc_workqueue("user_dlm", WQ_MEM_RECLAIM, 0);
590 if (!user_dlm_worker) {
591 status = -ENOMEM;
592 goto bail;
593 }
594 cleanup_worker = 1;
595
596 user_dlm_set_locking_protocol();
597 status = register_filesystem(&dlmfs_fs_type);
598 bail:
599 if (status) {
600 if (cleanup_inode)
601 kmem_cache_destroy(dlmfs_inode_cache);
602 if (cleanup_worker)
603 destroy_workqueue(user_dlm_worker);
604 } else
605 printk("OCFS2 User DLM kernel interface loaded\n");
606 return status;
607 }
608
609 static void __exit exit_dlmfs_fs(void)
610 {
611 unregister_filesystem(&dlmfs_fs_type);
612
613 destroy_workqueue(user_dlm_worker);
614
615 /*
616 * Make sure all delayed rcu free inodes are flushed before we
617 * destroy cache.
618 */
619 rcu_barrier();
620 kmem_cache_destroy(dlmfs_inode_cache);
621
622 }
623
624 MODULE_AUTHOR("Oracle");
625 MODULE_LICENSE("GPL");
626 MODULE_DESCRIPTION("OCFS2 DLM-Filesystem");
627
628 module_init(init_dlmfs_fs)
629 module_exit(exit_dlmfs_fs)
630
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