summaryrefslogtreecommitdiff
path: root/fs/nfs/unlink.c
blob: 5fa11e1aca4c2759358aa37c7c36691c1bc4bcd4 (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
// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/nfs/unlink.c
 *
 * nfs sillydelete handling
 *
 */

#include <linux/slab.h>
#include <linux/string.h>
#include <linux/dcache.h>
#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs_fs.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/namei.h>
#include <linux/fsnotify.h>

#include "internal.h"
#include "nfs4_fs.h"
#include "iostat.h"
#include "delegation.h"

#include "nfstrace.h"

/**
 * nfs_free_unlinkdata - release data from a sillydelete operation.
 * @data: pointer to unlink structure.
 */
static void
nfs_free_unlinkdata(struct nfs_unlinkdata *data)
{
	put_cred(data->cred);
	kfree(data->args.name.name);
	kfree(data);
}

/**
 * nfs_async_unlink_done - Sillydelete post-processing
 * @task: rpc_task of the sillydelete
 * @calldata: pointer to nfs_unlinkdata
 *
 * Do the directory attribute update.
 */
static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
{
	struct nfs_unlinkdata *data = calldata;
	struct inode *dir = d_inode(data->dentry->d_parent);

	trace_nfs_sillyrename_unlink(data, task->tk_status);
	if (!NFS_PROTO(dir)->unlink_done(task, dir))
		rpc_restart_call_prepare(task);
}

/**
 * nfs_async_unlink_release - Release the sillydelete data.
 * @calldata: struct nfs_unlinkdata to release
 *
 * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
 * rpc_task would be freed too.
 */
static void nfs_async_unlink_release(void *calldata)
{
	struct nfs_unlinkdata	*data = calldata;
	struct dentry *dentry = data->dentry;
	struct super_block *sb = dentry->d_sb;

	up_read_non_owner(&NFS_I(d_inode(dentry->d_parent))->rmdir_sem);
	d_lookup_done(dentry);
	nfs_free_unlinkdata(data);
	dput(dentry);
	nfs_sb_deactive(sb);
}

static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
{
	struct nfs_unlinkdata *data = calldata;
	struct inode *dir = d_inode(data->dentry->d_parent);
	NFS_PROTO(dir)->unlink_rpc_prepare(task, data);
}

static const struct rpc_call_ops nfs_unlink_ops = {
	.rpc_call_done = nfs_async_unlink_done,
	.rpc_release = nfs_async_unlink_release,
	.rpc_call_prepare = nfs_unlink_prepare,
};

static void nfs_do_call_unlink(struct inode *inode, struct nfs_unlinkdata *data)
{
	struct rpc_message msg = {
		.rpc_argp = &data->args,
		.rpc_resp = &data->res,
		.rpc_cred = data->cred,
	};
	struct rpc_task_setup task_setup_data = {
		.rpc_message = &msg,
		.callback_ops = &nfs_unlink_ops,
		.callback_data = data,
		.workqueue = nfsiod_workqueue,
		.flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF,
	};
	struct rpc_task *task;
	struct inode *dir = d_inode(data->dentry->d_parent);
	nfs_sb_active(dir->i_sb);
	data->args.fh = NFS_FH(dir);
	nfs_fattr_init(data->res.dir_attr);

	NFS_PROTO(dir)->unlink_setup(&msg, data->dentry, inode);

	task_setup_data.rpc_client = NFS_CLIENT(dir);
	task = rpc_run_task(&task_setup_data);
	if (!IS_ERR(task))
		rpc_put_task_async(task);
}

static int nfs_call_unlink(struct dentry *dentry, struct inode *inode, struct nfs_unlinkdata *data)
{
	struct inode *dir = d_inode(dentry->d_parent);
	struct dentry *alias;

	down_read_non_owner(&NFS_I(dir)->rmdir_sem);
	alias = d_alloc_parallel(dentry->d_parent, &data->args.name, &data->wq);
	if (IS_ERR(alias)) {
		up_read_non_owner(&NFS_I(dir)->rmdir_sem);
		return 0;
	}
	if (!d_in_lookup(alias)) {
		int ret;
		void *devname_garbage = NULL;

		/*
		 * Hey, we raced with lookup... See if we need to transfer
		 * the sillyrename information to the aliased dentry.
		 */
		spin_lock(&alias->d_lock);
		if (d_really_is_positive(alias) &&
		    !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
			devname_garbage = alias->d_fsdata;
			alias->d_fsdata = data;
			alias->d_flags |= DCACHE_NFSFS_RENAMED;
			ret = 1;
		} else
			ret = 0;
		spin_unlock(&alias->d_lock);
		dput(alias);
		up_read_non_owner(&NFS_I(dir)->rmdir_sem);
		/*
		 * If we'd displaced old cached devname, free it.  At that
		 * point dentry is definitely not a root, so we won't need
		 * that anymore.
		 */
		kfree(devname_garbage);
		return ret;
	}
	data->dentry = alias;
	nfs_do_call_unlink(inode, data);
	return 1;
}

/**
 * nfs_async_unlink - asynchronous unlinking of a file
 * @dentry: parent directory of dentry
 * @name: name of dentry to unlink
 */
static int
nfs_async_unlink(struct dentry *dentry, const struct qstr *name)
{
	struct nfs_unlinkdata *data;
	int status = -ENOMEM;
	void *devname_garbage = NULL;

	data = kzalloc(sizeof(*data), GFP_KERNEL);
	if (data == NULL)
		goto out;
	data->args.name.name = kstrdup(name->name, GFP_KERNEL);
	if (!data->args.name.name)
		goto out_free;
	data->args.name.len = name->len;

	data->cred = get_current_cred();
	data->res.dir_attr = &data->dir_attr;
	init_waitqueue_head(&data->wq);

	status = -EBUSY;
	spin_lock(&dentry->d_lock);
	if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
		goto out_unlock;
	dentry->d_flags |= DCACHE_NFSFS_RENAMED;
	devname_garbage = dentry->d_fsdata;
	dentry->d_fsdata = data;
	spin_unlock(&dentry->d_lock);
	/*
	 * If we'd displaced old cached devname, free it.  At that
	 * point dentry is definitely not a root, so we won't need
	 * that anymore.
	 */
	kfree(devname_garbage);
	return 0;
out_unlock:
	spin_unlock(&dentry->d_lock);
	put_cred(data->cred);
	kfree(data->args.name.name);
out_free:
	kfree(data);
out:
	return status;
}

/**
 * nfs_complete_unlink - Initialize completion of the sillydelete
 * @dentry: dentry to delete
 * @inode: inode
 *
 * Since we're most likely to be called by dentry_iput(), we
 * only use the dentry to find the sillydelete. We then copy the name
 * into the qstr.
 */
void
nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
{
	struct nfs_unlinkdata	*data;

	spin_lock(&dentry->d_lock);
	dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
	data = dentry->d_fsdata;
	dentry->d_fsdata = NULL;
	spin_unlock(&dentry->d_lock);

	if (NFS_STALE(inode) || !nfs_call_unlink(dentry, inode, data))
		nfs_free_unlinkdata(data);
}

/* Cancel a queued async unlink. Called when a sillyrename run fails. */
static void
nfs_cancel_async_unlink(struct dentry *dentry)
{
	spin_lock(&dentry->d_lock);
	if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
		struct nfs_unlinkdata *data = dentry->d_fsdata;

		dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
		dentry->d_fsdata = NULL;
		spin_unlock(&dentry->d_lock);
		nfs_free_unlinkdata(data);
		return;
	}
	spin_unlock(&dentry->d_lock);
}

/**
 * nfs_async_rename_done - Sillyrename post-processing
 * @task: rpc_task of the sillyrename
 * @calldata: nfs_renamedata for the sillyrename
 *
 * Do the directory attribute updates and the d_move
 */
static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
{
	struct nfs_renamedata *data = calldata;
	struct inode *old_dir = data->old_dir;
	struct inode *new_dir = data->new_dir;
	struct dentry *old_dentry = data->old_dentry;

	trace_nfs_sillyrename_rename(old_dir, old_dentry,
			new_dir, data->new_dentry, task->tk_status);
	if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
		rpc_restart_call_prepare(task);
		return;
	}

	if (data->complete)
		data->complete(task, data);
}

/**
 * nfs_async_rename_release - Release the sillyrename data.
 * @calldata: the struct nfs_renamedata to be released
 */
static void nfs_async_rename_release(void *calldata)
{
	struct nfs_renamedata	*data = calldata;
	struct super_block *sb = data->old_dir->i_sb;

	if (d_really_is_positive(data->old_dentry))
		nfs_mark_for_revalidate(d_inode(data->old_dentry));

	/* The result of the rename is unknown. Play it safe by
	 * forcing a new lookup */
	if (data->cancelled) {
		spin_lock(&data->old_dir->i_lock);
		nfs_force_lookup_revalidate(data->old_dir);
		spin_unlock(&data->old_dir->i_lock);
		if (data->new_dir != data->old_dir) {
			spin_lock(&data->new_dir->i_lock);
			nfs_force_lookup_revalidate(data->new_dir);
			spin_unlock(&data->new_dir->i_lock);
		}
	}

	dput(data->old_dentry);
	dput(data->new_dentry);
	iput(data->old_dir);
	iput(data->new_dir);
	nfs_sb_deactive(sb);
	put_cred(data->cred);
	kfree(data);
}

static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
{
	struct nfs_renamedata *data = calldata;
	NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data);
}

static const struct rpc_call_ops nfs_rename_ops = {
	.rpc_call_done = nfs_async_rename_done,
	.rpc_release = nfs_async_rename_release,
	.rpc_call_prepare = nfs_rename_prepare,
};

/**
 * nfs_async_rename - perform an asynchronous rename operation
 * @old_dir: directory that currently holds the dentry to be renamed
 * @new_dir: target directory for the rename
 * @old_dentry: original dentry to be renamed
 * @new_dentry: dentry to which the old_dentry should be renamed
 * @complete: Function to run on successful completion
 *
 * It's expected that valid references to the dentries and inodes are held
 */
struct rpc_task *
nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
		 struct dentry *old_dentry, struct dentry *new_dentry,
		 void (*complete)(struct rpc_task *, struct nfs_renamedata *))
{
	struct nfs_renamedata *data;
	struct rpc_message msg = { };
	struct rpc_task_setup task_setup_data = {
		.rpc_message = &msg,
		.callback_ops = &nfs_rename_ops,
		.workqueue = nfsiod_workqueue,
		.rpc_client = NFS_CLIENT(old_dir),
		.flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF,
	};

	data = kzalloc(sizeof(*data), GFP_KERNEL);
	if (data == NULL)
		return ERR_PTR(-ENOMEM);
	task_setup_data.callback_data = data;

	data->cred = get_current_cred();

	msg.rpc_argp = &data->args;
	msg.rpc_resp = &data->res;
	msg.rpc_cred = data->cred;

	/* set up nfs_renamedata */
	data->old_dir = old_dir;
	ihold(old_dir);
	data->new_dir = new_dir;
	ihold(new_dir);
	data->old_dentry = dget(old_dentry);
	data->new_dentry = dget(new_dentry);
	nfs_fattr_init(&data->old_fattr);
	nfs_fattr_init(&data->new_fattr);
	data->complete = complete;

	/* set up nfs_renameargs */
	data->args.old_dir = NFS_FH(old_dir);
	data->args.old_name = &old_dentry->d_name;
	data->args.new_dir = NFS_FH(new_dir);
	data->args.new_name = &new_dentry->d_name;

	/* set up nfs_renameres */
	data->res.old_fattr = &data->old_fattr;
	data->res.new_fattr = &data->new_fattr;

	nfs_sb_active(old_dir->i_sb);

	NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dentry, new_dentry);

	return rpc_run_task(&task_setup_data);
}

/*
 * Perform tasks needed when a sillyrename is done such as cancelling the
 * queued async unlink if it failed.
 */
static void
nfs_complete_sillyrename(struct rpc_task *task, struct nfs_renamedata *data)
{
	struct dentry *dentry = data->old_dentry;

	if (task->tk_status != 0) {
		nfs_cancel_async_unlink(dentry);
		return;
	}
}

#define SILLYNAME_PREFIX ".nfs"
#define SILLYNAME_PREFIX_LEN ((unsigned)sizeof(SILLYNAME_PREFIX) - 1)
#define SILLYNAME_FILEID_LEN ((unsigned)sizeof(u64) << 1)
#define SILLYNAME_COUNTER_LEN ((unsigned)sizeof(unsigned int) << 1)
#define SILLYNAME_LEN (SILLYNAME_PREFIX_LEN + \
		SILLYNAME_FILEID_LEN + \
		SILLYNAME_COUNTER_LEN)

/**
 * nfs_sillyrename - Perform a silly-rename of a dentry
 * @dir: inode of directory that contains dentry
 * @dentry: dentry to be sillyrenamed
 *
 * NFSv2/3 is stateless and the server doesn't know when the client is
 * holding a file open. To prevent application problems when a file is
 * unlinked while it's still open, the client performs a "silly-rename".
 * That is, it renames the file to a hidden file in the same directory,
 * and only performs the unlink once the last reference to it is put.
 *
 * The final cleanup is done during dentry_iput.
 *
 * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
 * could take responsibility for keeping open files referenced.  The server
 * would also need to ensure that opened-but-deleted files were kept over
 * reboots.  However, we may not assume a server does so.  (RFC 5661
 * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
 * use to advertise that it does this; some day we may take advantage of
 * it.))
 */
int
nfs_sillyrename(struct inode *dir, struct dentry *dentry)
{
	static unsigned int sillycounter;
	unsigned char silly[SILLYNAME_LEN + 1];
	unsigned long long fileid;
	struct dentry *sdentry;
	struct inode *inode = d_inode(dentry);
	struct rpc_task *task;
	int            error = -EBUSY;

	dfprintk(VFS, "NFS: silly-rename(%pd2, ct=%d)\n",
		dentry, d_count(dentry));
	nfs_inc_stats(dir, NFSIOS_SILLYRENAME);

	/*
	 * We don't allow a dentry to be silly-renamed twice.
	 */
	if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
		goto out;

	fileid = NFS_FILEID(d_inode(dentry));

	sdentry = NULL;
	do {
		int slen;
		dput(sdentry);
		sillycounter++;
		slen = scnprintf(silly, sizeof(silly),
				SILLYNAME_PREFIX "%0*llx%0*x",
				SILLYNAME_FILEID_LEN, fileid,
				SILLYNAME_COUNTER_LEN, sillycounter);

		dfprintk(VFS, "NFS: trying to rename %pd to %s\n",
				dentry, silly);

		sdentry = lookup_one_len(silly, dentry->d_parent, slen);
		/*
		 * N.B. Better to return EBUSY here ... it could be
		 * dangerous to delete the file while it's in use.
		 */
		if (IS_ERR(sdentry))
			goto out;
	} while (d_inode(sdentry) != NULL); /* need negative lookup */

	ihold(inode);

	/* queue unlink first. Can't do this from rpc_release as it
	 * has to allocate memory
	 */
	error = nfs_async_unlink(dentry, &sdentry->d_name);
	if (error)
		goto out_dput;

	/* run the rename task, undo unlink if it fails */
	task = nfs_async_rename(dir, dir, dentry, sdentry,
					nfs_complete_sillyrename);
	if (IS_ERR(task)) {
		error = -EBUSY;
		nfs_cancel_async_unlink(dentry);
		goto out_dput;
	}

	/* wait for the RPC task to complete, unless a SIGKILL intervenes */
	error = rpc_wait_for_completion_task(task);
	if (error == 0)
		error = task->tk_status;
	switch (error) {
	case 0:
		/* The rename succeeded */
		nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
		spin_lock(&inode->i_lock);
		NFS_I(inode)->attr_gencount = nfs_inc_attr_generation_counter();
		nfs_set_cache_invalid(inode, NFS_INO_INVALID_CHANGE |
						     NFS_INO_INVALID_CTIME |
						     NFS_INO_REVAL_FORCED);
		spin_unlock(&inode->i_lock);
		d_move(dentry, sdentry);
		break;
	case -ERESTARTSYS:
		/* The result of the rename is unknown. Play it safe by
		 * forcing a new lookup */
		d_drop(dentry);
		d_drop(sdentry);
	}
	rpc_put_task(task);
out_dput:
	iput(inode);
	dput(sdentry);
out:
	return error;
}