aboutsummaryrefslogtreecommitdiffstats
path: root/fs/ocfs2/dcache.c
blob: e5ba348183321d133ab7f75c715b305dbed28a07 (plain) (blame)
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
/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * dcache.c
 *
 * dentry cache handling code
 *
 * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/fs.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/namei.h>

#include <cluster/masklog.h>

#include "ocfs2.h"

#include "alloc.h"
#include "dcache.h"
#include "dlmglue.h"
#include "file.h"
#include "inode.h"
#include "super.h"
#include "ocfs2_trace.h"

void ocfs2_dentry_attach_gen(struct dentry *dentry)
{
	unsigned long gen =
		OCFS2_I(dentry->d_parent->d_inode)->ip_dir_lock_gen;
	BUG_ON(dentry->d_inode);
	dentry->d_fsdata = (void *)gen;
}


static int ocfs2_dentry_revalidate(struct dentry *dentry,
				   struct nameidata *nd)
{
	struct inode *inode;
	int ret = 0;    /* if all else fails, just return false */
	struct ocfs2_super *osb;

	if (nd && nd->flags & LOOKUP_RCU)
		return -ECHILD;

	inode = dentry->d_inode;
	osb = OCFS2_SB(dentry->d_sb);

	trace_ocfs2_dentry_revalidate(dentry, dentry->d_name.len,
				      dentry->d_name.name);

	/* For a negative dentry -
	 * check the generation number of the parent and compare with the
	 * one stored in the inode.
	 */
	if (inode == NULL) {
		unsigned long gen = (unsigned long) dentry->d_fsdata;
		unsigned long pgen =
			OCFS2_I(dentry->d_parent->d_inode)->ip_dir_lock_gen;

		trace_ocfs2_dentry_revalidate_negative(dentry->d_name.len,
						       dentry->d_name.name,
						       pgen, gen);
		if (gen != pgen)
			goto bail;
		goto valid;
	}

	BUG_ON(!osb);

	if (inode == osb->root_inode || is_bad_inode(inode))
		goto bail;

	spin_lock(&OCFS2_I(inode)->ip_lock);
	/* did we or someone else delete this inode? */
	if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED) {
		spin_unlock(&OCFS2_I(inode)->ip_lock);
		trace_ocfs2_dentry_revalidate_delete(
				(unsigned long long)OCFS2_I(inode)->ip_blkno);
		goto bail;
	}
	spin_unlock(&OCFS2_I(inode)->ip_lock);

	/*
	 * We don't need a cluster lock to test this because once an
	 * inode nlink hits zero, it never goes back.
	 */
	if (inode->i_nlink == 0) {
		trace_ocfs2_dentry_revalidate_orphaned(
			(unsigned long long)OCFS2_I(inode)->ip_blkno,
			S_ISDIR(inode->i_mode));
		goto bail;
	}

	/*
	 * If the last lookup failed to create dentry lock, let us
	 * redo it.
	 */
	if (!dentry->d_fsdata) {
		trace_ocfs2_dentry_revalidate_nofsdata(
				(unsigned long long)OCFS2_I(inode)->ip_blkno);
		goto bail;
	}

valid:
	ret = 1;

bail:
	trace_ocfs2_dentry_revalidate_ret(ret);
	return ret;
}

static int ocfs2_match_dentry(struct dentry *dentry,
			      u64 parent_blkno,
			      int skip_unhashed)
{
	struct inode *parent;

	/*
	 * ocfs2_lookup() does a d_splice_alias() _before_ attaching
	 * to the lock data, so we skip those here, otherwise
	 * ocfs2_dentry_attach_lock() will get its original dentry
	 * back.
	 */
	if (!dentry->d_fsdata)
		return 0;

	if (!dentry->d_parent)
		return 0;

	if (skip_unhashed && d_unhashed(dentry))
		return 0;

	parent = dentry->d_parent->d_inode;
	/* Negative parent dentry? */
	if (!parent)
		return 0;

	/* Name is in a different directory. */
	if (OCFS2_I(parent)->ip_blkno != parent_blkno)
		return 0;

	return 1;
}

/*
 * Walk the inode alias list, and find a dentry which has a given
 * parent. ocfs2_dentry_attach_lock() wants to find _any_ alias as it
 * is looking for a dentry_lock reference. The downconvert thread is
 * looking to unhash aliases, so we allow it to skip any that already
 * have that property.
 */
struct dentry *ocfs2_find_local_alias(struct inode *inode,
				      u64 parent_blkno,
				      int skip_unhashed)
{
	struct list_head *p;
	struct dentry *dentry = NULL;

	spin_lock(&inode->i_lock);
	list_for_each(p, &inode->i_dentry) {
		dentry = list_entry(p, struct dentry, d_alias);

		spin_lock(&dentry->d_lock);
		if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) {
			trace_ocfs2_find_local_alias(dentry->d_name.len,
						     dentry->d_name.name);

			dget_dlock(dentry);
			spin_unlock(&dentry->d_lock);
			break;
		}
		spin_unlock(&dentry->d_lock);

		dentry = NULL;
	}

	spin_unlock(&inode->i_lock);

	return dentry;
}

DEFINE_SPINLOCK(dentry_attach_lock);

/*
 * Attach this dentry to a cluster lock.
 *
 * Dentry locks cover all links in a given directory to a particular
 * inode. We do this so that ocfs2 can build a lock name which all
 * nodes in the cluster can agree on at all times. Shoving full names
 * in the cluster lock won't work due to size restrictions. Covering
 * links inside of a directory is a good compromise because it still
 * allows us to use the parent directory lock to synchronize
 * operations.
 *
 * Call this function with the parent dir semaphore and the parent dir
 * cluster lock held.
 *
 * The dir semaphore will protect us from having to worry about
 * concurrent processes on our node trying to attach a lock at the
 * same time.
 *
 * The dir cluster lock (held at either PR or EX mode) protects us
 * from unlink and rename on other nodes.
 *
 * A dput() can happen asynchronously due to pruning, so we cover
 * attaching and detaching the dentry lock with a
 * dentry_attach_lock.
 *
 * A node which has done lookup on a name retains a protected read
 * lock until final dput. If the user requests and unlink or rename,
 * the protected read is upgraded to an exclusive lock. Other nodes
 * who have seen the dentry will then be informed that they need to
 * downgrade their lock, which will involve d_delete on the
 * dentry. This happens in ocfs2_dentry_convert_worker().
 */
int ocfs2_dentry_attach_lock(struct dentry *dentry,
			     struct inode *inode,
			     u64 parent_blkno)
{
	int ret;
	struct dentry *alias;
	struct ocfs2_dentry_lock *dl = dentry->d_fsdata;

	trace_ocfs2_dentry_attach_lock(dentry->d_name.len, dentry->d_name.name,
				       (unsigned long long)parent_blkno, dl);

	/*
	 * Negative dentry. We ignore these for now.
	 *
	 * XXX: Could we can improve ocfs2_dentry_revalidate() by
	 * tracking these?
	 */
	if (!inode)
		return 0;

	if (!dentry->d_inode && dentry->d_fsdata) {
		/* Converting a negative dentry to positive
		   Clear dentry->d_fsdata */
		dentry->d_fsdata = dl = NULL;
	}

	if (dl) {
		mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
				" \"%.*s\": old parent: %llu, new: %llu\n",
				dentry->d_name.len, dentry->d_name.name,
				(unsigned long long)parent_blkno,
				(unsigned long long)dl->dl_parent_blkno);
		return 0;
	}

	alias = ocfs2_find_local_alias(inode, parent_blkno, 0);
	if (alias) {
		/*
		 * Great, an alias exists, which means we must have a
		 * dentry lock already. We can just grab the lock off
		 * the alias and add it to the list.
		 *
		 * We're depending here on the fact that this dentry
		 * was found and exists in the dcache and so must have
		 * a reference to the dentry_lock because we can't
		 * race creates. Final dput() cannot happen on it
		 * since we have it pinned, so our reference is safe.
		 */
		dl = alias->d_fsdata;
		mlog_bug_on_msg(!dl, "parent %llu, ino %llu\n",
				(unsigned long long)parent_blkno,
				(unsigned long long)OCFS2_I(inode)->ip_blkno);

		mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
				" \"%.*s\": old parent: %llu, new: %llu\n",
				dentry->d_name.len, dentry->d_name.name,
				(unsigned long long)parent_blkno,
				(unsigned long long)dl->dl_parent_blkno);

		trace_ocfs2_dentry_attach_lock_found(dl->dl_lockres.l_name,
				(unsigned long long)parent_blkno,
				(unsigned long long)OCFS2_I(inode)->ip_blkno);

		goto out_attach;
	}

	/*
	 * There are no other aliases
	 */
	dl = kmalloc(sizeof(*dl), GFP_NOFS);
	if (!dl) {
		ret = -ENOMEM;
		mlog_errno(ret);
		return ret;
	}

	dl->dl_count = 0;
	/*
	 * Does this have to happen below, for all attaches, in case
	 * the struct inode gets blown away by the downconvert thread?
	 */
	dl->dl_inode = igrab(inode);
	dl->dl_parent_blkno = parent_blkno;
	ocfs2_dentry_lock_res_init(dl, parent_blkno, inode);

out_attach:
	spin_lock(&dentry_attach_lock);
	dentry->d_fsdata = dl;
	dl->dl_count++;
	spin_unlock(&dentry_attach_lock);

	/*
	 * This actually gets us our PRMODE level lock. From now on,
	 * we'll have a notification if one of these names is
	 * destroyed on another node.
	 */
	ret = ocfs2_dentry_lock(dentry, 0);
	if (!ret)
		ocfs2_dentry_unlock(dentry, 0);
	else
		mlog_errno(ret);

	/*
	 * In case of error, manually free the allocation and do the iput().
	 * We need to do this because error here means no d_instantiate(),
	 * which means iput() will not be called during dput(dentry).
	 */
	if (ret < 0 && !alias) {
		ocfs2_lock_res_free(&dl->dl_lockres);
		BUG_ON(dl->dl_count != 1);
		spin_lock(&dentry_attach_lock);
		dentry->d_fsdata = NULL;
		spin_unlock(&dentry_attach_lock);
		kfree(dl);
		iput(inode);
	}

	dput(alias);

	return ret;
}

DEFINE_SPINLOCK(dentry_list_lock);

/* We limit the number of dentry locks to drop in one go. We have
 * this limit so that we don't starve other users of ocfs2_wq. */
#define DL_INODE_DROP_COUNT 64

/* Drop inode references from dentry locks */
static void __ocfs2_drop_dl_inodes(struct ocfs2_super *osb, int drop_count)
{
	struct ocfs2_dentry_lock *dl;

	spin_lock(&dentry_list_lock);
	while (osb->dentry_lock_list && (drop_count < 0 || drop_count--)) {
		dl = osb->dentry_lock_list;
		osb->dentry_lock_list = dl->dl_next;
		spin_unlock(&dentry_list_lock);
		iput(dl->dl_inode);
		kfree(dl);
		spin_lock(&dentry_list_lock);
	}
	spin_unlock(&dentry_list_lock);
}

void ocfs2_drop_dl_inodes(struct work_struct *work)
{
	struct ocfs2_super *osb = container_of(work, struct ocfs2_super,
					       dentry_lock_work);

	__ocfs2_drop_dl_inodes(osb, DL_INODE_DROP_COUNT);
	/*
	 * Don't queue dropping if umount is in progress. We flush the
	 * list in ocfs2_dismount_volume
	 */
	spin_lock(&dentry_list_lock);
	if (osb->dentry_lock_list &&
	    !ocfs2_test_osb_flag(osb, OCFS2_OSB_DROP_DENTRY_LOCK_IMMED))
		queue_work(ocfs2_wq, &osb->dentry_lock_work);
	spin_unlock(&dentry_list_lock);
}

/* Flush the whole work queue */
void ocfs2_drop_all_dl_inodes(struct ocfs2_super *osb)
{
	__ocfs2_drop_dl_inodes(osb, -1);
}

/*
 * ocfs2_dentry_iput() and friends.
 *
 * At this point, our particular dentry is detached from the inodes
 * alias list, so there's no way that the locking code can find it.
 *
 * The interesting stuff happens when we determine that our lock needs
 * to go away because this is the last subdir alias in the
 * system. This function needs to handle a couple things:
 *
 * 1) Synchronizing lock shutdown with the downconvert threads. This
 *    is already handled for us via the lockres release drop function
 *    called in ocfs2_release_dentry_lock()
 *
 * 2) A race may occur when we're doing our lock shutdown and
 *    another process wants to create a new dentry lock. Right now we
 *    let them race, which means that for a very short while, this
 *    node might have two locks on a lock resource. This should be a
 *    problem though because one of them is in the process of being
 *    thrown out.
 */
static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb,
				   struct ocfs2_dentry_lock *dl)
{
	ocfs2_simple_drop_lockres(osb, &dl->dl_lockres);
	ocfs2_lock_res_free(&dl->dl_lockres);

	/* We leave dropping of inode reference to ocfs2_wq as that can
	 * possibly lead to inode deletion which gets tricky */
	spin_lock(&dentry_list_lock);
	if (!osb->dentry_lock_list &&
	    !ocfs2_test_osb_flag(osb, OCFS2_OSB_DROP_DENTRY_LOCK_IMMED))
		queue_work(ocfs2_wq, &osb->dentry_lock_work);
	dl->dl_next = osb->dentry_lock_list;
	osb->dentry_lock_list = dl;
	spin_unlock(&dentry_list_lock);
}

void ocfs2_dentry_lock_put(struct ocfs2_super *osb,
			   struct ocfs2_dentry_lock *dl)
{
	int unlock;

	BUG_ON(dl->dl_count == 0);

	spin_lock(&dentry_attach_lock);
	dl->dl_count--;
	unlock = !dl->dl_count;
	spin_unlock(&dentry_attach_lock);

	if (unlock)
		ocfs2_drop_dentry_lock(osb, dl);
}

static void ocfs2_dentry_iput(struct dentry *dentry, struct inode *inode)
{
	struct ocfs2_dentry_lock *dl = dentry->d_fsdata;

	if (!dl) {
		/*
		 * No dentry lock is ok if we're disconnected or
		 * unhashed.
		 */
		if (!(dentry->d_flags & DCACHE_DISCONNECTED) &&
		    !d_unhashed(dentry)) {
			unsigned long long ino = 0ULL;
			if (inode)
				ino = (unsigned long long)OCFS2_I(inode)->ip_blkno;
			mlog(ML_ERROR, "Dentry is missing cluster lock. "
			     "inode: %llu, d_flags: 0x%x, d_name: %.*s\n",
			     ino, dentry->d_flags, dentry->d_name.len,
			     dentry->d_name.name);
		}

		goto out;
	}

	mlog_bug_on_msg(dl->dl_count == 0, "dentry: %.*s, count: %u\n",
			dentry->d_name.len, dentry->d_name.name,
			dl->dl_count);

	ocfs2_dentry_lock_put(OCFS2_SB(dentry->d_sb), dl);

out:
	iput(inode);
}

/*
 * d_move(), but keep the locks in sync.
 *
 * When we are done, "dentry" will have the parent dir and name of
 * "target", which will be thrown away.
 *
 * We manually update the lock of "dentry" if need be.
 *
 * "target" doesn't have it's dentry lock touched - we allow the later
 * dput() to handle this for us.
 *
 * This is called during ocfs2_rename(), while holding parent
 * directory locks. The dentries have already been deleted on other
 * nodes via ocfs2_remote_dentry_delete().
 *
 * Normally, the VFS handles the d_move() for the file system, after
 * the ->rename() callback. OCFS2 wants to handle this internally, so
 * the new lock can be created atomically with respect to the cluster.
 */
void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target,
		       struct inode *old_dir, struct inode *new_dir)
{
	int ret;
	struct ocfs2_super *osb = OCFS2_SB(old_dir->i_sb);
	struct inode *inode = dentry->d_inode;

	/*
	 * Move within the same directory, so the actual lock info won't
	 * change.
	 *
	 * XXX: Is there any advantage to dropping the lock here?
	 */
	if (old_dir == new_dir)
		goto out_move;

	ocfs2_dentry_lock_put(osb, dentry->d_fsdata);

	dentry->d_fsdata = NULL;
	ret = ocfs2_dentry_attach_lock(dentry, inode, OCFS2_I(new_dir)->ip_blkno);
	if (ret)
		mlog_errno(ret);

out_move:
	d_move(dentry, target);
}

const struct dentry_operations ocfs2_dentry_ops = {
	.d_revalidate		= ocfs2_dentry_revalidate,
	.d_iput			= ocfs2_dentry_iput,
};