summaryrefslogtreecommitdiff
path: root/fs/ocfs2/dlmfs/dlmfs.c
blob: ba26c5567cff775ce129ddf09ab7eac1f5e70bef (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * dlmfs.c
 *
 * Code which implements the kernel side of a minimal userspace
 * interface to our DLM. This file handles the virtual file system
 * used for communication with userspace. Credit should go to ramfs,
 * which was a template for the fs side of this module.
 *
 * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
 */

/* Simple VFS hooks based on: */
/*
 * Resizable simple ram filesystem for Linux.
 *
 * Copyright (C) 2000 Linus Torvalds.
 *               2000 Transmeta Corp.
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/backing-dev.h>
#include <linux/poll.h>

#include <linux/uaccess.h>

#include "../stackglue.h"
#include "userdlm.h"

#define MLOG_MASK_PREFIX ML_DLMFS
#include "../cluster/masklog.h"


static const struct super_operations dlmfs_ops;
static const struct file_operations dlmfs_file_operations;
static const struct inode_operations dlmfs_dir_inode_operations;
static const struct inode_operations dlmfs_root_inode_operations;
static const struct inode_operations dlmfs_file_inode_operations;
static struct kmem_cache *dlmfs_inode_cache;

struct workqueue_struct *user_dlm_worker;



/*
 * These are the ABI capabilities of dlmfs.
 *
 * Over time, dlmfs has added some features that were not part of the
 * initial ABI.  Unfortunately, some of these features are not detectable
 * via standard usage.  For example, Linux's default poll always returns
 * EPOLLIN, so there is no way for a caller of poll(2) to know when dlmfs
 * added poll support.  Instead, we provide this list of new capabilities.
 *
 * Capabilities is a read-only attribute.  We do it as a module parameter
 * so we can discover it whether dlmfs is built in, loaded, or even not
 * loaded.
 *
 * The ABI features are local to this machine's dlmfs mount.  This is
 * distinct from the locking protocol, which is concerned with inter-node
 * interaction.
 *
 * Capabilities:
 * - bast	: EPOLLIN against the file descriptor of a held lock
 *		  signifies a bast fired on the lock.
 */
#define DLMFS_CAPABILITIES "bast stackglue"
static int param_set_dlmfs_capabilities(const char *val,
					const struct kernel_param *kp)
{
	printk(KERN_ERR "%s: readonly parameter\n", kp->name);
	return -EINVAL;
}
static int param_get_dlmfs_capabilities(char *buffer,
					const struct kernel_param *kp)
{
	return strlcpy(buffer, DLMFS_CAPABILITIES,
		       strlen(DLMFS_CAPABILITIES) + 1);
}
module_param_call(capabilities, param_set_dlmfs_capabilities,
		  param_get_dlmfs_capabilities, NULL, 0444);
MODULE_PARM_DESC(capabilities, DLMFS_CAPABILITIES);


/*
 * decodes a set of open flags into a valid lock level and a set of flags.
 * returns < 0 if we have invalid flags
 * flags which mean something to us:
 * O_RDONLY -> PRMODE level
 * O_WRONLY -> EXMODE level
 *
 * O_NONBLOCK -> NOQUEUE
 */
static int dlmfs_decode_open_flags(int open_flags,
				   int *level,
				   int *flags)
{
	if (open_flags & (O_WRONLY|O_RDWR))
		*level = DLM_LOCK_EX;
	else
		*level = DLM_LOCK_PR;

	*flags = 0;
	if (open_flags & O_NONBLOCK)
		*flags |= DLM_LKF_NOQUEUE;

	return 0;
}

static int dlmfs_file_open(struct inode *inode,
			   struct file *file)
{
	int status, level, flags;
	struct dlmfs_filp_private *fp = NULL;
	struct dlmfs_inode_private *ip;

	if (S_ISDIR(inode->i_mode))
		BUG();

	mlog(0, "open called on inode %lu, flags 0x%x\n", inode->i_ino,
		file->f_flags);

	status = dlmfs_decode_open_flags(file->f_flags, &level, &flags);
	if (status < 0)
		goto bail;

	/* We don't want to honor O_APPEND at read/write time as it
	 * doesn't make sense for LVB writes. */
	file->f_flags &= ~O_APPEND;

	fp = kmalloc(sizeof(*fp), GFP_NOFS);
	if (!fp) {
		status = -ENOMEM;
		goto bail;
	}
	fp->fp_lock_level = level;

	ip = DLMFS_I(inode);

	status = user_dlm_cluster_lock(&ip->ip_lockres, level, flags);
	if (status < 0) {
		/* this is a strange error to return here but I want
		 * to be able userspace to be able to distinguish a
		 * valid lock request from one that simply couldn't be
		 * granted. */
		if (flags & DLM_LKF_NOQUEUE && status == -EAGAIN)
			status = -ETXTBSY;
		kfree(fp);
		goto bail;
	}

	file->private_data = fp;
bail:
	return status;
}

static int dlmfs_file_release(struct inode *inode,
			      struct file *file)
{
	int level;
	struct dlmfs_inode_private *ip = DLMFS_I(inode);
	struct dlmfs_filp_private *fp = file->private_data;

	if (S_ISDIR(inode->i_mode))
		BUG();

	mlog(0, "close called on inode %lu\n", inode->i_ino);

	if (fp) {
		level = fp->fp_lock_level;
		if (level != DLM_LOCK_IV)
			user_dlm_cluster_unlock(&ip->ip_lockres, level);

		kfree(fp);
		file->private_data = NULL;
	}

	return 0;
}

/*
 * We do ->setattr() just to override size changes.  Our size is the size
 * of the LVB and nothing else.
 */
static int dlmfs_file_setattr(struct mnt_idmap *idmap,
			      struct dentry *dentry, struct iattr *attr)
{
	int error;
	struct inode *inode = d_inode(dentry);

	attr->ia_valid &= ~ATTR_SIZE;
	error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
	if (error)
		return error;

	setattr_copy(&nop_mnt_idmap, inode, attr);
	mark_inode_dirty(inode);
	return 0;
}

static __poll_t dlmfs_file_poll(struct file *file, poll_table *wait)
{
	__poll_t event = 0;
	struct inode *inode = file_inode(file);
	struct dlmfs_inode_private *ip = DLMFS_I(inode);

	poll_wait(file, &ip->ip_lockres.l_event, wait);

	spin_lock(&ip->ip_lockres.l_lock);
	if (ip->ip_lockres.l_flags & USER_LOCK_BLOCKED)
		event = EPOLLIN | EPOLLRDNORM;
	spin_unlock(&ip->ip_lockres.l_lock);

	return event;
}

static ssize_t dlmfs_file_read(struct file *file,
			       char __user *buf,
			       size_t count,
			       loff_t *ppos)
{
	char lvb[DLM_LVB_LEN];

	if (!user_dlm_read_lvb(file_inode(file), lvb))
		return 0;

	return simple_read_from_buffer(buf, count, ppos, lvb, sizeof(lvb));
}

static ssize_t dlmfs_file_write(struct file *filp,
				const char __user *buf,
				size_t count,
				loff_t *ppos)
{
	char lvb_buf[DLM_LVB_LEN];
	int bytes_left;
	struct inode *inode = file_inode(filp);

	mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
		inode->i_ino, count, *ppos);

	if (*ppos >= DLM_LVB_LEN)
		return -ENOSPC;

	/* don't write past the lvb */
	if (count > DLM_LVB_LEN - *ppos)
		count = DLM_LVB_LEN - *ppos;

	if (!count)
		return 0;

	bytes_left = copy_from_user(lvb_buf, buf, count);
	count -= bytes_left;
	if (count)
		user_dlm_write_lvb(inode, lvb_buf, count);

	*ppos = *ppos + count;
	mlog(0, "wrote %zu bytes\n", count);
	return count;
}

static void dlmfs_init_once(void *foo)
{
	struct dlmfs_inode_private *ip =
		(struct dlmfs_inode_private *) foo;

	ip->ip_conn = NULL;
	ip->ip_parent = NULL;

	inode_init_once(&ip->ip_vfs_inode);
}

static struct inode *dlmfs_alloc_inode(struct super_block *sb)
{
	struct dlmfs_inode_private *ip;

	ip = alloc_inode_sb(sb, dlmfs_inode_cache, GFP_NOFS);
	if (!ip)
		return NULL;

	return &ip->ip_vfs_inode;
}

static void dlmfs_free_inode(struct inode *inode)
{
	kmem_cache_free(dlmfs_inode_cache, DLMFS_I(inode));
}

static void dlmfs_evict_inode(struct inode *inode)
{
	int status;
	struct dlmfs_inode_private *ip;
	struct user_lock_res *lockres;
	int teardown;

	clear_inode(inode);

	mlog(0, "inode %lu\n", inode->i_ino);

	ip = DLMFS_I(inode);
	lockres = &ip->ip_lockres;

	if (S_ISREG(inode->i_mode)) {
		spin_lock(&lockres->l_lock);
		teardown = !!(lockres->l_flags & USER_LOCK_IN_TEARDOWN);
		spin_unlock(&lockres->l_lock);
		if (!teardown) {
			status = user_dlm_destroy_lock(lockres);
			if (status < 0)
				mlog_errno(status);
		}
		iput(ip->ip_parent);
		goto clear_fields;
	}

	mlog(0, "we're a directory, ip->ip_conn = 0x%p\n", ip->ip_conn);
	/* we must be a directory. If required, lets unregister the
	 * dlm context now. */
	if (ip->ip_conn)
		user_dlm_unregister(ip->ip_conn);
clear_fields:
	ip->ip_parent = NULL;
	ip->ip_conn = NULL;
}

static struct inode *dlmfs_get_root_inode(struct super_block *sb)
{
	struct inode *inode = new_inode(sb);
	umode_t mode = S_IFDIR | 0755;

	if (inode) {
		inode->i_ino = get_next_ino();
		inode_init_owner(&nop_mnt_idmap, inode, NULL, mode);
		inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
		inc_nlink(inode);

		inode->i_fop = &simple_dir_operations;
		inode->i_op = &dlmfs_root_inode_operations;
	}

	return inode;
}

static struct inode *dlmfs_get_inode(struct inode *parent,
				     struct dentry *dentry,
				     umode_t mode)
{
	struct super_block *sb = parent->i_sb;
	struct inode * inode = new_inode(sb);
	struct dlmfs_inode_private *ip;

	if (!inode)
		return NULL;

	inode->i_ino = get_next_ino();
	inode_init_owner(&nop_mnt_idmap, inode, parent, mode);
	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);

	ip = DLMFS_I(inode);
	ip->ip_conn = DLMFS_I(parent)->ip_conn;

	switch (mode & S_IFMT) {
	default:
		/* for now we don't support anything other than
		 * directories and regular files. */
		BUG();
		break;
	case S_IFREG:
		inode->i_op = &dlmfs_file_inode_operations;
		inode->i_fop = &dlmfs_file_operations;

		i_size_write(inode,  DLM_LVB_LEN);

		user_dlm_lock_res_init(&ip->ip_lockres, dentry);

		/* released at clear_inode time, this insures that we
		 * get to drop the dlm reference on each lock *before*
		 * we call the unregister code for releasing parent
		 * directories. */
		ip->ip_parent = igrab(parent);
		BUG_ON(!ip->ip_parent);
		break;
	case S_IFDIR:
		inode->i_op = &dlmfs_dir_inode_operations;
		inode->i_fop = &simple_dir_operations;

		/* directory inodes start off with i_nlink ==
		 * 2 (for "." entry) */
		inc_nlink(inode);
		break;
	}
	return inode;
}

/*
 * File creation. Allocate an inode, and we're done..
 */
/* SMP-safe */
static int dlmfs_mkdir(struct mnt_idmap * idmap,
		       struct inode * dir,
		       struct dentry * dentry,
		       umode_t mode)
{
	int status;
	struct inode *inode = NULL;
	const struct qstr *domain = &dentry->d_name;
	struct dlmfs_inode_private *ip;
	struct ocfs2_cluster_connection *conn;

	mlog(0, "mkdir %.*s\n", domain->len, domain->name);

	/* verify that we have a proper domain */
	if (domain->len >= GROUP_NAME_MAX) {
		status = -EINVAL;
		mlog(ML_ERROR, "invalid domain name for directory.\n");
		goto bail;
	}

	inode = dlmfs_get_inode(dir, dentry, mode | S_IFDIR);
	if (!inode) {
		status = -ENOMEM;
		mlog_errno(status);
		goto bail;
	}

	ip = DLMFS_I(inode);

	conn = user_dlm_register(domain);
	if (IS_ERR(conn)) {
		status = PTR_ERR(conn);
		mlog(ML_ERROR, "Error %d could not register domain \"%.*s\"\n",
		     status, domain->len, domain->name);
		goto bail;
	}
	ip->ip_conn = conn;

	inc_nlink(dir);
	d_instantiate(dentry, inode);
	dget(dentry);	/* Extra count - pin the dentry in core */

	status = 0;
bail:
	if (status < 0)
		iput(inode);
	return status;
}

static int dlmfs_create(struct mnt_idmap *idmap,
			struct inode *dir,
			struct dentry *dentry,
			umode_t mode,
			bool excl)
{
	int status = 0;
	struct inode *inode;
	const struct qstr *name = &dentry->d_name;

	mlog(0, "create %.*s\n", name->len, name->name);

	/* verify name is valid and doesn't contain any dlm reserved
	 * characters */
	if (name->len >= USER_DLM_LOCK_ID_MAX_LEN ||
	    name->name[0] == '$') {
		status = -EINVAL;
		mlog(ML_ERROR, "invalid lock name, %.*s\n", name->len,
		     name->name);
		goto bail;
	}

	inode = dlmfs_get_inode(dir, dentry, mode | S_IFREG);
	if (!inode) {
		status = -ENOMEM;
		mlog_errno(status);
		goto bail;
	}

	d_instantiate(dentry, inode);
	dget(dentry);	/* Extra count - pin the dentry in core */
bail:
	return status;
}

static int dlmfs_unlink(struct inode *dir,
			struct dentry *dentry)
{
	int status;
	struct inode *inode = d_inode(dentry);

	mlog(0, "unlink inode %lu\n", inode->i_ino);

	/* if there are no current holders, or none that are waiting
	 * to acquire a lock, this basically destroys our lockres. */
	status = user_dlm_destroy_lock(&DLMFS_I(inode)->ip_lockres);
	if (status < 0) {
		mlog(ML_ERROR, "unlink %pd, error %d from destroy\n",
		     dentry, status);
		goto bail;
	}
	status = simple_unlink(dir, dentry);
bail:
	return status;
}

static int dlmfs_fill_super(struct super_block * sb,
			    void * data,
			    int silent)
{
	sb->s_maxbytes = MAX_LFS_FILESIZE;
	sb->s_blocksize = PAGE_SIZE;
	sb->s_blocksize_bits = PAGE_SHIFT;
	sb->s_magic = DLMFS_MAGIC;
	sb->s_op = &dlmfs_ops;
	sb->s_root = d_make_root(dlmfs_get_root_inode(sb));
	if (!sb->s_root)
		return -ENOMEM;
	return 0;
}

static const struct file_operations dlmfs_file_operations = {
	.open		= dlmfs_file_open,
	.release	= dlmfs_file_release,
	.poll		= dlmfs_file_poll,
	.read		= dlmfs_file_read,
	.write		= dlmfs_file_write,
	.llseek		= default_llseek,
};

static const struct inode_operations dlmfs_dir_inode_operations = {
	.create		= dlmfs_create,
	.lookup		= simple_lookup,
	.unlink		= dlmfs_unlink,
};

/* this way we can restrict mkdir to only the toplevel of the fs. */
static const struct inode_operations dlmfs_root_inode_operations = {
	.lookup		= simple_lookup,
	.mkdir		= dlmfs_mkdir,
	.rmdir		= simple_rmdir,
};

static const struct super_operations dlmfs_ops = {
	.statfs		= simple_statfs,
	.alloc_inode	= dlmfs_alloc_inode,
	.free_inode	= dlmfs_free_inode,
	.evict_inode	= dlmfs_evict_inode,
	.drop_inode	= generic_delete_inode,
};

static const struct inode_operations dlmfs_file_inode_operations = {
	.getattr	= simple_getattr,
	.setattr	= dlmfs_file_setattr,
};

static struct dentry *dlmfs_mount(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data)
{
	return mount_nodev(fs_type, flags, data, dlmfs_fill_super);
}

static struct file_system_type dlmfs_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "ocfs2_dlmfs",
	.mount		= dlmfs_mount,
	.kill_sb	= kill_litter_super,
};
MODULE_ALIAS_FS("ocfs2_dlmfs");

static int __init init_dlmfs_fs(void)
{
	int status;
	int cleanup_inode = 0, cleanup_worker = 0;

	dlmfs_inode_cache = kmem_cache_create("dlmfs_inode_cache",
				sizeof(struct dlmfs_inode_private),
				0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
					SLAB_MEM_SPREAD|SLAB_ACCOUNT),
				dlmfs_init_once);
	if (!dlmfs_inode_cache) {
		status = -ENOMEM;
		goto bail;
	}
	cleanup_inode = 1;

	user_dlm_worker = alloc_workqueue("user_dlm", WQ_MEM_RECLAIM, 0);
	if (!user_dlm_worker) {
		status = -ENOMEM;
		goto bail;
	}
	cleanup_worker = 1;

	user_dlm_set_locking_protocol();
	status = register_filesystem(&dlmfs_fs_type);
bail:
	if (status) {
		if (cleanup_inode)
			kmem_cache_destroy(dlmfs_inode_cache);
		if (cleanup_worker)
			destroy_workqueue(user_dlm_worker);
	} else
		printk("OCFS2 User DLM kernel interface loaded\n");
	return status;
}

static void __exit exit_dlmfs_fs(void)
{
	unregister_filesystem(&dlmfs_fs_type);

	destroy_workqueue(user_dlm_worker);

	/*
	 * Make sure all delayed rcu free inodes are flushed before we
	 * destroy cache.
	 */
	rcu_barrier();
	kmem_cache_destroy(dlmfs_inode_cache);

}

MODULE_AUTHOR("Oracle");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("OCFS2 DLM-Filesystem");

module_init(init_dlmfs_fs)
module_exit(exit_dlmfs_fs)