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/fs_context.h>
24#include <linux/pagemap.h>
25#include <linux/types.h>
26#include <linux/slab.h>
27#include <linux/highmem.h>
28#include <linux/init.h>
29#include <linux/string.h>
30#include <linux/backing-dev.h>
31#include <linux/poll.h>
32
33#include <linux/uaccess.h>
34
35#include "../stackglue.h"
36#include "userdlm.h"
37
38#define MLOG_MASK_PREFIX ML_DLMFS
39#include "../cluster/masklog.h"
40
41
42static const struct super_operations dlmfs_ops;
43static const struct file_operations dlmfs_file_operations;
44static const struct inode_operations dlmfs_dir_inode_operations;
45static const struct inode_operations dlmfs_root_inode_operations;
46static const struct inode_operations dlmfs_file_inode_operations;
47static struct kmem_cache *dlmfs_inode_cache;
48
49struct workqueue_struct *user_dlm_worker;
50
51
52
53/*
54 * These are the ABI capabilities of dlmfs.
55 *
56 * Over time, dlmfs has added some features that were not part of the
57 * initial ABI. Unfortunately, some of these features are not detectable
58 * via standard usage. For example, Linux's default poll always returns
59 * EPOLLIN, so there is no way for a caller of poll(2) to know when dlmfs
60 * added poll support. Instead, we provide this list of new capabilities.
61 *
62 * Capabilities is a read-only attribute. We do it as a module parameter
63 * so we can discover it whether dlmfs is built in, loaded, or even not
64 * loaded.
65 *
66 * The ABI features are local to this machine's dlmfs mount. This is
67 * distinct from the locking protocol, which is concerned with inter-node
68 * interaction.
69 *
70 * Capabilities:
71 * - bast : EPOLLIN against the file descriptor of a held lock
72 * signifies a bast fired on the lock.
73 */
74#define DLMFS_CAPABILITIES "bast stackglue"
75static int param_set_dlmfs_capabilities(const char *val,
76 const struct kernel_param *kp)
77{
78 printk(KERN_ERR "%s: readonly parameter\n", kp->name);
79 return -EINVAL;
80}
81static int param_get_dlmfs_capabilities(char *buffer,
82 const struct kernel_param *kp)
83{
84 return sysfs_emit(buf: buffer, DLMFS_CAPABILITIES);
85}
86module_param_call(capabilities, param_set_dlmfs_capabilities,
87 param_get_dlmfs_capabilities, NULL, 0444);
88MODULE_PARM_DESC(capabilities, DLMFS_CAPABILITIES);
89
90
91/*
92 * decodes a set of open flags into a valid lock level and a set of flags.
93 * returns < 0 if we have invalid flags
94 * flags which mean something to us:
95 * O_RDONLY -> PRMODE level
96 * O_WRONLY -> EXMODE level
97 *
98 * O_NONBLOCK -> NOQUEUE
99 */
100static int dlmfs_decode_open_flags(int open_flags,
101 int *level,
102 int *flags)
103{
104 if (open_flags & (O_WRONLY|O_RDWR))
105 *level = DLM_LOCK_EX;
106 else
107 *level = DLM_LOCK_PR;
108
109 *flags = 0;
110 if (open_flags & O_NONBLOCK)
111 *flags |= DLM_LKF_NOQUEUE;
112
113 return 0;
114}
115
116static int dlmfs_file_open(struct inode *inode,
117 struct file *file)
118{
119 int status, level, flags;
120 struct dlmfs_filp_private *fp = NULL;
121 struct dlmfs_inode_private *ip;
122
123 if (S_ISDIR(inode->i_mode))
124 BUG();
125
126 mlog(0, "open called on inode %lu, flags 0x%x\n", inode->i_ino,
127 file->f_flags);
128
129 status = dlmfs_decode_open_flags(open_flags: file->f_flags, level: &level, flags: &flags);
130 if (status < 0)
131 goto bail;
132
133 /* We don't want to honor O_APPEND at read/write time as it
134 * doesn't make sense for LVB writes. */
135 file->f_flags &= ~O_APPEND;
136
137 fp = kmalloc(sizeof(*fp), GFP_NOFS);
138 if (!fp) {
139 status = -ENOMEM;
140 goto bail;
141 }
142 fp->fp_lock_level = level;
143
144 ip = DLMFS_I(inode);
145
146 status = user_dlm_cluster_lock(lockres: &ip->ip_lockres, level, lkm_flags: flags);
147 if (status < 0) {
148 /* this is a strange error to return here but I want
149 * to be able userspace to be able to distinguish a
150 * valid lock request from one that simply couldn't be
151 * granted. */
152 if (flags & DLM_LKF_NOQUEUE && status == -EAGAIN)
153 status = -ETXTBSY;
154 kfree(objp: fp);
155 goto bail;
156 }
157
158 file->private_data = fp;
159bail:
160 return status;
161}
162
163static int dlmfs_file_release(struct inode *inode,
164 struct file *file)
165{
166 int level;
167 struct dlmfs_inode_private *ip = DLMFS_I(inode);
168 struct dlmfs_filp_private *fp = file->private_data;
169
170 if (S_ISDIR(inode->i_mode))
171 BUG();
172
173 mlog(0, "close called on inode %lu\n", inode->i_ino);
174
175 if (fp) {
176 level = fp->fp_lock_level;
177 if (level != DLM_LOCK_IV)
178 user_dlm_cluster_unlock(lockres: &ip->ip_lockres, level);
179
180 kfree(objp: fp);
181 file->private_data = NULL;
182 }
183
184 return 0;
185}
186
187/*
188 * We do ->setattr() just to override size changes. Our size is the size
189 * of the LVB and nothing else.
190 */
191static int dlmfs_file_setattr(struct mnt_idmap *idmap,
192 struct dentry *dentry, struct iattr *attr)
193{
194 int error;
195 struct inode *inode = d_inode(dentry);
196
197 attr->ia_valid &= ~ATTR_SIZE;
198 error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
199 if (error)
200 return error;
201
202 setattr_copy(&nop_mnt_idmap, inode, attr);
203 mark_inode_dirty(inode);
204 return 0;
205}
206
207static __poll_t dlmfs_file_poll(struct file *file, poll_table *wait)
208{
209 __poll_t event = 0;
210 struct inode *inode = file_inode(f: file);
211 struct dlmfs_inode_private *ip = DLMFS_I(inode);
212
213 poll_wait(filp: file, wait_address: &ip->ip_lockres.l_event, p: wait);
214
215 spin_lock(lock: &ip->ip_lockres.l_lock);
216 if (ip->ip_lockres.l_flags & USER_LOCK_BLOCKED)
217 event = EPOLLIN | EPOLLRDNORM;
218 spin_unlock(lock: &ip->ip_lockres.l_lock);
219
220 return event;
221}
222
223static ssize_t dlmfs_file_read(struct file *file,
224 char __user *buf,
225 size_t count,
226 loff_t *ppos)
227{
228 char lvb[DLM_LVB_LEN];
229
230 if (!user_dlm_read_lvb(inode: file_inode(f: file), val: lvb))
231 return 0;
232
233 return simple_read_from_buffer(to: buf, count, ppos, from: lvb, available: sizeof(lvb));
234}
235
236static ssize_t dlmfs_file_write(struct file *filp,
237 const char __user *buf,
238 size_t count,
239 loff_t *ppos)
240{
241 char lvb_buf[DLM_LVB_LEN];
242 int bytes_left;
243 struct inode *inode = file_inode(f: filp);
244
245 mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
246 inode->i_ino, count, *ppos);
247
248 if (*ppos >= DLM_LVB_LEN)
249 return -ENOSPC;
250
251 /* don't write past the lvb */
252 if (count > DLM_LVB_LEN - *ppos)
253 count = DLM_LVB_LEN - *ppos;
254
255 if (!count)
256 return 0;
257
258 bytes_left = copy_from_user(to: lvb_buf, from: buf, n: count);
259 count -= bytes_left;
260 if (count)
261 user_dlm_write_lvb(inode, val: lvb_buf, len: count);
262
263 *ppos = *ppos + count;
264 mlog(0, "wrote %zu bytes\n", count);
265 return count;
266}
267
268static void dlmfs_init_once(void *foo)
269{
270 struct dlmfs_inode_private *ip =
271 (struct dlmfs_inode_private *) foo;
272
273 ip->ip_conn = NULL;
274 ip->ip_parent = NULL;
275
276 inode_init_once(&ip->ip_vfs_inode);
277}
278
279static struct inode *dlmfs_alloc_inode(struct super_block *sb)
280{
281 struct dlmfs_inode_private *ip;
282
283 ip = alloc_inode_sb(sb, dlmfs_inode_cache, GFP_NOFS);
284 if (!ip)
285 return NULL;
286
287 return &ip->ip_vfs_inode;
288}
289
290static void dlmfs_free_inode(struct inode *inode)
291{
292 kmem_cache_free(s: dlmfs_inode_cache, objp: DLMFS_I(inode));
293}
294
295static void dlmfs_evict_inode(struct inode *inode)
296{
297 int status;
298 struct dlmfs_inode_private *ip;
299 struct user_lock_res *lockres;
300 int teardown;
301
302 clear_inode(inode);
303
304 mlog(0, "inode %lu\n", inode->i_ino);
305
306 ip = DLMFS_I(inode);
307 lockres = &ip->ip_lockres;
308
309 if (S_ISREG(inode->i_mode)) {
310 spin_lock(lock: &lockres->l_lock);
311 teardown = !!(lockres->l_flags & USER_LOCK_IN_TEARDOWN);
312 spin_unlock(lock: &lockres->l_lock);
313 if (!teardown) {
314 status = user_dlm_destroy_lock(lockres);
315 if (status < 0)
316 mlog_errno(status);
317 }
318 iput(ip->ip_parent);
319 goto clear_fields;
320 }
321
322 mlog(0, "we're a directory, ip->ip_conn = 0x%p\n", ip->ip_conn);
323 /* we must be a directory. If required, lets unregister the
324 * dlm context now. */
325 if (ip->ip_conn)
326 user_dlm_unregister(conn: ip->ip_conn);
327clear_fields:
328 ip->ip_parent = NULL;
329 ip->ip_conn = NULL;
330}
331
332static struct inode *dlmfs_get_root_inode(struct super_block *sb)
333{
334 struct inode *inode = new_inode(sb);
335 umode_t mode = S_IFDIR | 0755;
336
337 if (inode) {
338 inode->i_ino = get_next_ino();
339 inode_init_owner(idmap: &nop_mnt_idmap, inode, NULL, mode);
340 simple_inode_init_ts(inode);
341 inc_nlink(inode);
342
343 inode->i_fop = &simple_dir_operations;
344 inode->i_op = &dlmfs_root_inode_operations;
345 }
346
347 return inode;
348}
349
350static struct inode *dlmfs_get_inode(struct inode *parent,
351 struct dentry *dentry,
352 umode_t mode)
353{
354 struct super_block *sb = parent->i_sb;
355 struct inode * inode = new_inode(sb);
356 struct dlmfs_inode_private *ip;
357
358 if (!inode)
359 return NULL;
360
361 inode->i_ino = get_next_ino();
362 inode_init_owner(idmap: &nop_mnt_idmap, inode, dir: parent, mode);
363 simple_inode_init_ts(inode);
364
365 ip = DLMFS_I(inode);
366 ip->ip_conn = DLMFS_I(inode: parent)->ip_conn;
367
368 switch (mode & S_IFMT) {
369 default:
370 /* for now we don't support anything other than
371 * directories and regular files. */
372 BUG();
373 break;
374 case S_IFREG:
375 inode->i_op = &dlmfs_file_inode_operations;
376 inode->i_fop = &dlmfs_file_operations;
377
378 i_size_write(inode, DLM_LVB_LEN);
379
380 user_dlm_lock_res_init(lockres: &ip->ip_lockres, dentry);
381
382 /* released at clear_inode time, this insures that we
383 * get to drop the dlm reference on each lock *before*
384 * we call the unregister code for releasing parent
385 * directories. */
386 ip->ip_parent = igrab(parent);
387 BUG_ON(!ip->ip_parent);
388 break;
389 case S_IFDIR:
390 inode->i_op = &dlmfs_dir_inode_operations;
391 inode->i_fop = &simple_dir_operations;
392
393 /* directory inodes start off with i_nlink ==
394 * 2 (for "." entry) */
395 inc_nlink(inode);
396 break;
397 }
398 return inode;
399}
400
401/*
402 * File creation. Allocate an inode, and we're done..
403 */
404/* SMP-safe */
405static struct dentry *dlmfs_mkdir(struct mnt_idmap * idmap,
406 struct inode * dir,
407 struct dentry * dentry,
408 umode_t mode)
409{
410 int status;
411 struct inode *inode = NULL;
412 const struct qstr *domain = &dentry->d_name;
413 struct dlmfs_inode_private *ip;
414 struct ocfs2_cluster_connection *conn;
415
416 mlog(0, "mkdir %.*s\n", domain->len, domain->name);
417
418 /* verify that we have a proper domain */
419 if (domain->len >= GROUP_NAME_MAX) {
420 status = -EINVAL;
421 mlog(ML_ERROR, "invalid domain name for directory.\n");
422 goto bail;
423 }
424
425 inode = dlmfs_get_inode(parent: dir, dentry, mode: mode | S_IFDIR);
426 if (!inode) {
427 status = -ENOMEM;
428 mlog_errno(status);
429 goto bail;
430 }
431
432 ip = DLMFS_I(inode);
433
434 conn = user_dlm_register(name: domain);
435 if (IS_ERR(ptr: conn)) {
436 status = PTR_ERR(ptr: conn);
437 mlog(ML_ERROR, "Error %d could not register domain \"%.*s\"\n",
438 status, domain->len, domain->name);
439 goto bail;
440 }
441 ip->ip_conn = conn;
442
443 inc_nlink(inode: dir);
444 d_make_persistent(dentry, inode);
445
446 status = 0;
447bail:
448 if (status < 0)
449 iput(inode);
450 return ERR_PTR(error: status);
451}
452
453static 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(parent: dir, dentry, mode: mode | S_IFREG);
476 if (!inode) {
477 status = -ENOMEM;
478 mlog_errno(status);
479 goto bail;
480 }
481
482 d_make_persistent(dentry, inode);
483bail:
484 return status;
485}
486
487static int dlmfs_unlink(struct inode *dir,
488 struct dentry *dentry)
489{
490 int status;
491 struct inode *inode = d_inode(dentry);
492
493 mlog(0, "unlink inode %lu\n", inode->i_ino);
494
495 /* if there are no current holders, or none that are waiting
496 * to acquire a lock, this basically destroys our lockres. */
497 status = user_dlm_destroy_lock(lockres: &DLMFS_I(inode)->ip_lockres);
498 if (status < 0) {
499 mlog(ML_ERROR, "unlink %pd, error %d from destroy\n",
500 dentry, status);
501 goto bail;
502 }
503 status = simple_unlink(dir, dentry);
504bail:
505 return status;
506}
507
508static int dlmfs_fill_super(struct super_block *sb, struct fs_context *fc)
509{
510 sb->s_maxbytes = MAX_LFS_FILESIZE;
511 sb->s_blocksize = PAGE_SIZE;
512 sb->s_blocksize_bits = PAGE_SHIFT;
513 sb->s_magic = DLMFS_MAGIC;
514 sb->s_op = &dlmfs_ops;
515 sb->s_root = d_make_root(dlmfs_get_root_inode(sb));
516 if (!sb->s_root)
517 return -ENOMEM;
518 return 0;
519}
520
521static const struct file_operations dlmfs_file_operations = {
522 .open = dlmfs_file_open,
523 .release = dlmfs_file_release,
524 .poll = dlmfs_file_poll,
525 .read = dlmfs_file_read,
526 .write = dlmfs_file_write,
527 .llseek = default_llseek,
528};
529
530static const struct inode_operations dlmfs_dir_inode_operations = {
531 .create = dlmfs_create,
532 .lookup = simple_lookup,
533 .unlink = dlmfs_unlink,
534};
535
536/* this way we can restrict mkdir to only the toplevel of the fs. */
537static const struct inode_operations dlmfs_root_inode_operations = {
538 .lookup = simple_lookup,
539 .mkdir = dlmfs_mkdir,
540 .rmdir = simple_rmdir,
541};
542
543static const struct super_operations dlmfs_ops = {
544 .statfs = simple_statfs,
545 .alloc_inode = dlmfs_alloc_inode,
546 .free_inode = dlmfs_free_inode,
547 .evict_inode = dlmfs_evict_inode,
548 .drop_inode = inode_just_drop,
549};
550
551static const struct inode_operations dlmfs_file_inode_operations = {
552 .getattr = simple_getattr,
553 .setattr = dlmfs_file_setattr,
554};
555
556static int dlmfs_get_tree(struct fs_context *fc)
557{
558 return get_tree_nodev(fc, fill_super: dlmfs_fill_super);
559}
560
561static const struct fs_context_operations dlmfs_context_ops = {
562 .get_tree = dlmfs_get_tree,
563};
564
565static int dlmfs_init_fs_context(struct fs_context *fc)
566{
567 fc->ops = &dlmfs_context_ops;
568
569 return 0;
570}
571
572static struct file_system_type dlmfs_fs_type = {
573 .owner = THIS_MODULE,
574 .name = "ocfs2_dlmfs",
575 .kill_sb = kill_anon_super,
576 .init_fs_context = dlmfs_init_fs_context,
577};
578MODULE_ALIAS_FS("ocfs2_dlmfs");
579
580static int __init init_dlmfs_fs(void)
581{
582 int status;
583 int cleanup_inode = 0, cleanup_worker = 0;
584
585 dlmfs_inode_cache = kmem_cache_create("dlmfs_inode_cache",
586 sizeof(struct dlmfs_inode_private),
587 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
588 SLAB_ACCOUNT),
589 dlmfs_init_once);
590 if (!dlmfs_inode_cache) {
591 status = -ENOMEM;
592 goto bail;
593 }
594 cleanup_inode = 1;
595
596 user_dlm_worker = alloc_workqueue("user_dlm",
597 WQ_MEM_RECLAIM | WQ_PERCPU, 0);
598 if (!user_dlm_worker) {
599 status = -ENOMEM;
600 goto bail;
601 }
602 cleanup_worker = 1;
603
604 user_dlm_set_locking_protocol();
605 status = register_filesystem(&dlmfs_fs_type);
606bail:
607 if (status) {
608 if (cleanup_inode)
609 kmem_cache_destroy(s: dlmfs_inode_cache);
610 if (cleanup_worker)
611 destroy_workqueue(wq: user_dlm_worker);
612 } else
613 printk("OCFS2 User DLM kernel interface loaded\n");
614 return status;
615}
616
617static void __exit exit_dlmfs_fs(void)
618{
619 unregister_filesystem(&dlmfs_fs_type);
620
621 destroy_workqueue(wq: user_dlm_worker);
622
623 /*
624 * Make sure all delayed rcu free inodes are flushed before we
625 * destroy cache.
626 */
627 rcu_barrier();
628 kmem_cache_destroy(s: dlmfs_inode_cache);
629
630}
631
632MODULE_AUTHOR("Oracle");
633MODULE_LICENSE("GPL");
634MODULE_DESCRIPTION("OCFS2 DLM-Filesystem");
635
636module_init(init_dlmfs_fs)
637module_exit(exit_dlmfs_fs)
638

source code of linux/fs/ocfs2/dlmfs/dlmfs.c