blob: 014e73978dac074aa406f4494f9e6288515a88a3 [file] [log] [blame]
Mark Fashehccd979b2005-12-15 14:31:24 -08001/* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * dcache.c
5 *
6 * dentry cache handling code
7 *
8 * Copyright (C) 2002, 2004 Oracle. All rights reserved.
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public
12 * License as published by the Free Software Foundation; either
13 * version 2 of the License, or (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public
21 * License along with this program; if not, write to the
22 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
23 * Boston, MA 021110-1307, USA.
24 */
25
26#include <linux/fs.h>
27#include <linux/types.h>
28#include <linux/slab.h>
29#include <linux/namei.h>
30
31#define MLOG_MASK_PREFIX ML_DCACHE
32#include <cluster/masklog.h>
33
34#include "ocfs2.h"
35
36#include "alloc.h"
37#include "dcache.h"
Mark Fasheh80c05842006-09-08 14:43:18 -070038#include "dlmglue.h"
Mark Fashehccd979b2005-12-15 14:31:24 -080039#include "file.h"
40#include "inode.h"
41
Mark Fasheh80c05842006-09-08 14:43:18 -070042
Mark Fashehccd979b2005-12-15 14:31:24 -080043static int ocfs2_dentry_revalidate(struct dentry *dentry,
44 struct nameidata *nd)
45{
46 struct inode *inode = dentry->d_inode;
47 int ret = 0; /* if all else fails, just return false */
Mark Fasheh80c05842006-09-08 14:43:18 -070048 struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
Mark Fashehccd979b2005-12-15 14:31:24 -080049
50 mlog_entry("(0x%p, '%.*s')\n", dentry,
51 dentry->d_name.len, dentry->d_name.name);
52
53 /* Never trust a negative dentry - force a new lookup. */
54 if (inode == NULL) {
55 mlog(0, "negative dentry: %.*s\n", dentry->d_name.len,
56 dentry->d_name.name);
57 goto bail;
58 }
59
Mark Fashehccd979b2005-12-15 14:31:24 -080060 BUG_ON(!osb);
61
Mark Fasheh80c05842006-09-08 14:43:18 -070062 if (inode == osb->root_inode || is_bad_inode(inode))
63 goto bail;
Mark Fashehccd979b2005-12-15 14:31:24 -080064
Mark Fasheh80c05842006-09-08 14:43:18 -070065 spin_lock(&OCFS2_I(inode)->ip_lock);
66 /* did we or someone else delete this inode? */
67 if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED) {
68 spin_unlock(&OCFS2_I(inode)->ip_lock);
69 mlog(0, "inode (%llu) deleted, returning false\n",
70 (unsigned long long)OCFS2_I(inode)->ip_blkno);
71 goto bail;
72 }
73 spin_unlock(&OCFS2_I(inode)->ip_lock);
74
75 /*
76 * We don't need a cluster lock to test this because once an
77 * inode nlink hits zero, it never goes back.
78 */
79 if (inode->i_nlink == 0) {
80 mlog(0, "Inode %llu orphaned, returning false "
81 "dir = %d\n",
82 (unsigned long long)OCFS2_I(inode)->ip_blkno,
83 S_ISDIR(inode->i_mode));
84 goto bail;
Mark Fashehccd979b2005-12-15 14:31:24 -080085 }
86
87 ret = 1;
88
89bail:
90 mlog_exit(ret);
91
92 return ret;
93}
94
Mark Fasheh80c05842006-09-08 14:43:18 -070095static int ocfs2_match_dentry(struct dentry *dentry,
96 u64 parent_blkno,
97 int skip_unhashed)
98{
99 struct inode *parent;
100
101 /*
102 * ocfs2_lookup() does a d_splice_alias() _before_ attaching
103 * to the lock data, so we skip those here, otherwise
104 * ocfs2_dentry_attach_lock() will get its original dentry
105 * back.
106 */
107 if (!dentry->d_fsdata)
108 return 0;
109
110 if (!dentry->d_parent)
111 return 0;
112
113 if (skip_unhashed && d_unhashed(dentry))
114 return 0;
115
116 parent = dentry->d_parent->d_inode;
117 /* Negative parent dentry? */
118 if (!parent)
119 return 0;
120
121 /* Name is in a different directory. */
122 if (OCFS2_I(parent)->ip_blkno != parent_blkno)
123 return 0;
124
125 return 1;
126}
127
128/*
129 * Walk the inode alias list, and find a dentry which has a given
130 * parent. ocfs2_dentry_attach_lock() wants to find _any_ alias as it
131 * is looking for a dentry_lock reference. The vote thread is looking
132 * to unhash aliases, so we allow it to skip any that already have
133 * that property.
134 */
135struct dentry *ocfs2_find_local_alias(struct inode *inode,
136 u64 parent_blkno,
137 int skip_unhashed)
138{
139 struct list_head *p;
140 struct dentry *dentry = NULL;
141
142 spin_lock(&dcache_lock);
143
144 list_for_each(p, &inode->i_dentry) {
145 dentry = list_entry(p, struct dentry, d_alias);
146
147 if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) {
148 mlog(0, "dentry found: %.*s\n",
149 dentry->d_name.len, dentry->d_name.name);
150
151 dget_locked(dentry);
152 break;
153 }
154
155 dentry = NULL;
156 }
157
158 spin_unlock(&dcache_lock);
159
160 return dentry;
161}
162
Mark Fashehd680efe2006-09-08 14:14:34 -0700163DEFINE_SPINLOCK(dentry_attach_lock);
164
Mark Fasheh80c05842006-09-08 14:43:18 -0700165/*
166 * Attach this dentry to a cluster lock.
167 *
168 * Dentry locks cover all links in a given directory to a particular
169 * inode. We do this so that ocfs2 can build a lock name which all
170 * nodes in the cluster can agree on at all times. Shoving full names
171 * in the cluster lock won't work due to size restrictions. Covering
172 * links inside of a directory is a good compromise because it still
173 * allows us to use the parent directory lock to synchronize
174 * operations.
175 *
176 * Call this function with the parent dir semaphore and the parent dir
177 * cluster lock held.
178 *
179 * The dir semaphore will protect us from having to worry about
180 * concurrent processes on our node trying to attach a lock at the
181 * same time.
182 *
183 * The dir cluster lock (held at either PR or EX mode) protects us
184 * from unlink and rename on other nodes.
185 *
Mark Fasheh80c05842006-09-08 14:43:18 -0700186 * A dput() can happen asynchronously due to pruning, so we cover
187 * attaching and detaching the dentry lock with a
188 * dentry_attach_lock.
189 *
190 * A node which has done lookup on a name retains a protected read
191 * lock until final dput. If the user requests and unlink or rename,
192 * the protected read is upgraded to an exclusive lock. Other nodes
193 * who have seen the dentry will then be informed that they need to
194 * downgrade their lock, which will involve d_delete on the
195 * dentry. This happens in ocfs2_dentry_convert_worker().
196 */
197int ocfs2_dentry_attach_lock(struct dentry *dentry,
198 struct inode *inode,
Mark Fasheh0027dd52006-09-21 16:51:28 -0700199 u64 parent_blkno)
Mark Fasheh80c05842006-09-08 14:43:18 -0700200{
201 int ret;
202 struct dentry *alias;
203 struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
204
Mark Fasheh0027dd52006-09-21 16:51:28 -0700205 mlog(0, "Attach \"%.*s\", parent %llu, fsdata: %p\n",
Mark Fasheh80c05842006-09-08 14:43:18 -0700206 dentry->d_name.len, dentry->d_name.name,
Mark Fasheh0027dd52006-09-21 16:51:28 -0700207 (unsigned long long)parent_blkno, dl);
Mark Fasheh80c05842006-09-08 14:43:18 -0700208
209 /*
210 * Negative dentry. We ignore these for now.
211 *
212 * XXX: Could we can improve ocfs2_dentry_revalidate() by
213 * tracking these?
214 */
215 if (!inode)
216 return 0;
217
218 if (dl) {
219 mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
220 " \"%.*s\": old parent: %llu, new: %llu\n",
221 dentry->d_name.len, dentry->d_name.name,
222 (unsigned long long)parent_blkno,
223 (unsigned long long)dl->dl_parent_blkno);
224 return 0;
225 }
226
227 alias = ocfs2_find_local_alias(inode, parent_blkno, 0);
228 if (alias) {
229 /*
230 * Great, an alias exists, which means we must have a
231 * dentry lock already. We can just grab the lock off
232 * the alias and add it to the list.
233 *
234 * We're depending here on the fact that this dentry
235 * was found and exists in the dcache and so must have
236 * a reference to the dentry_lock because we can't
237 * race creates. Final dput() cannot happen on it
238 * since we have it pinned, so our reference is safe.
239 */
240 dl = alias->d_fsdata;
Mark Fasheh0027dd52006-09-21 16:51:28 -0700241 mlog_bug_on_msg(!dl, "parent %llu, ino %llu\n",
Mark Fasheh80c05842006-09-08 14:43:18 -0700242 (unsigned long long)parent_blkno,
Mark Fasheh0027dd52006-09-21 16:51:28 -0700243 (unsigned long long)OCFS2_I(inode)->ip_blkno);
Mark Fasheh80c05842006-09-08 14:43:18 -0700244
245 mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
246 " \"%.*s\": old parent: %llu, new: %llu\n",
247 dentry->d_name.len, dentry->d_name.name,
248 (unsigned long long)parent_blkno,
249 (unsigned long long)dl->dl_parent_blkno);
250
251 mlog(0, "Found: %s\n", dl->dl_lockres.l_name);
252
253 goto out_attach;
254 }
255
256 /*
257 * There are no other aliases
258 */
259 dl = kmalloc(sizeof(*dl), GFP_NOFS);
260 if (!dl) {
261 ret = -ENOMEM;
262 mlog_errno(ret);
263 return ret;
264 }
265
266 dl->dl_count = 0;
267 /*
268 * Does this have to happen below, for all attaches, in case
269 * the struct inode gets blown away by votes?
270 */
271 dl->dl_inode = igrab(inode);
272 dl->dl_parent_blkno = parent_blkno;
273 ocfs2_dentry_lock_res_init(dl, parent_blkno, inode);
274
275out_attach:
276 spin_lock(&dentry_attach_lock);
277 dentry->d_fsdata = dl;
278 dl->dl_count++;
279 spin_unlock(&dentry_attach_lock);
280
281 /*
Mark Fasheh80c05842006-09-08 14:43:18 -0700282 * This actually gets us our PRMODE level lock. From now on,
283 * we'll have a notification if one of these names is
284 * destroyed on another node.
285 */
286 ret = ocfs2_dentry_lock(dentry, 0);
Mark Fasheh0027dd52006-09-21 16:51:28 -0700287 if (!ret)
288 ocfs2_dentry_unlock(dentry, 0);
289 else
Mark Fasheh80c05842006-09-08 14:43:18 -0700290 mlog_errno(ret);
Mark Fasheh80c05842006-09-08 14:43:18 -0700291
Mark Fasheh80c05842006-09-08 14:43:18 -0700292 dput(alias);
293
294 return ret;
295}
296
297/*
298 * ocfs2_dentry_iput() and friends.
299 *
300 * At this point, our particular dentry is detached from the inodes
301 * alias list, so there's no way that the locking code can find it.
302 *
303 * The interesting stuff happens when we determine that our lock needs
304 * to go away because this is the last subdir alias in the
305 * system. This function needs to handle a couple things:
306 *
307 * 1) Synchronizing lock shutdown with the downconvert threads. This
308 * is already handled for us via the lockres release drop function
309 * called in ocfs2_release_dentry_lock()
310 *
311 * 2) A race may occur when we're doing our lock shutdown and
312 * another process wants to create a new dentry lock. Right now we
313 * let them race, which means that for a very short while, this
314 * node might have two locks on a lock resource. This should be a
315 * problem though because one of them is in the process of being
316 * thrown out.
317 */
318static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb,
319 struct ocfs2_dentry_lock *dl)
320{
321 ocfs2_simple_drop_lockres(osb, &dl->dl_lockres);
322 ocfs2_lock_res_free(&dl->dl_lockres);
323 iput(dl->dl_inode);
324 kfree(dl);
325}
326
327void ocfs2_dentry_lock_put(struct ocfs2_super *osb,
328 struct ocfs2_dentry_lock *dl)
329{
330 int unlock = 0;
331
332 BUG_ON(dl->dl_count == 0);
333
334 spin_lock(&dentry_attach_lock);
335 dl->dl_count--;
336 unlock = !dl->dl_count;
337 spin_unlock(&dentry_attach_lock);
338
339 if (unlock)
340 ocfs2_drop_dentry_lock(osb, dl);
341}
342
343static void ocfs2_dentry_iput(struct dentry *dentry, struct inode *inode)
344{
345 struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
346
347 mlog_bug_on_msg(!dl && !(dentry->d_flags & DCACHE_DISCONNECTED),
348 "dentry: %.*s\n", dentry->d_name.len,
349 dentry->d_name.name);
350
351 if (!dl)
352 goto out;
353
354 mlog_bug_on_msg(dl->dl_count == 0, "dentry: %.*s, count: %u\n",
355 dentry->d_name.len, dentry->d_name.name,
356 dl->dl_count);
357
358 ocfs2_dentry_lock_put(OCFS2_SB(dentry->d_sb), dl);
359
360out:
361 iput(inode);
362}
363
364/*
365 * d_move(), but keep the locks in sync.
366 *
367 * When we are done, "dentry" will have the parent dir and name of
368 * "target", which will be thrown away.
369 *
370 * We manually update the lock of "dentry" if need be.
371 *
372 * "target" doesn't have it's dentry lock touched - we allow the later
373 * dput() to handle this for us.
374 *
375 * This is called during ocfs2_rename(), while holding parent
376 * directory locks. The dentries have already been deleted on other
377 * nodes via ocfs2_remote_dentry_delete().
378 *
379 * Normally, the VFS handles the d_move() for the file sytem, after
380 * the ->rename() callback. OCFS2 wants to handle this internally, so
381 * the new lock can be created atomically with respect to the cluster.
382 */
383void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target,
384 struct inode *old_dir, struct inode *new_dir)
385{
386 int ret;
387 struct ocfs2_super *osb = OCFS2_SB(old_dir->i_sb);
388 struct inode *inode = dentry->d_inode;
389
390 /*
391 * Move within the same directory, so the actual lock info won't
392 * change.
393 *
394 * XXX: Is there any advantage to dropping the lock here?
395 */
396 if (old_dir == new_dir)
Mark Fasheh1ba9da22006-09-08 14:22:54 -0700397 goto out_move;
Mark Fasheh80c05842006-09-08 14:43:18 -0700398
399 ocfs2_dentry_lock_put(osb, dentry->d_fsdata);
400
401 dentry->d_fsdata = NULL;
Mark Fasheh0027dd52006-09-21 16:51:28 -0700402 ret = ocfs2_dentry_attach_lock(dentry, inode, OCFS2_I(new_dir)->ip_blkno);
Mark Fasheh80c05842006-09-08 14:43:18 -0700403 if (ret)
404 mlog_errno(ret);
Mark Fasheh1ba9da22006-09-08 14:22:54 -0700405
406out_move:
407 d_move(dentry, target);
Mark Fasheh80c05842006-09-08 14:43:18 -0700408}
409
Mark Fashehccd979b2005-12-15 14:31:24 -0800410struct dentry_operations ocfs2_dentry_ops = {
411 .d_revalidate = ocfs2_dentry_revalidate,
Mark Fasheh80c05842006-09-08 14:43:18 -0700412 .d_iput = ocfs2_dentry_iput,
Mark Fashehccd979b2005-12-15 14:31:24 -0800413};