1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/nfs/unlink.c
4 *
5 * nfs sillydelete handling
6 *
7 */
8
9 #include <linux/slab.h>
10 #include <linux/string.h>
11 #include <linux/dcache.h>
12 #include <linux/sunrpc/sched.h>
13 #include <linux/sunrpc/clnt.h>
14 #include <linux/nfs_fs.h>
15 #include <linux/sched.h>
16 #include <linux/wait.h>
17 #include <linux/namei.h>
18 #include <linux/fsnotify.h>
19
20 #include "internal.h"
21 #include "nfs4_fs.h"
22 #include "iostat.h"
23 #include "delegation.h"
24
25 #include "nfstrace.h"
26
27 /**
28 * nfs_free_unlinkdata - release data from a sillydelete operation.
29 * @data: pointer to unlink structure.
30 */
31 static void
nfs_free_unlinkdata(struct nfs_unlinkdata * data)32 nfs_free_unlinkdata(struct nfs_unlinkdata *data)
33 {
34 put_cred(data->cred);
35 kfree(data->args.name.name);
36 kfree(data);
37 }
38
39 /**
40 * nfs_async_unlink_done - Sillydelete post-processing
41 * @task: rpc_task of the sillydelete
42 * @calldata: pointer to nfs_unlinkdata
43 *
44 * Do the directory attribute update.
45 */
nfs_async_unlink_done(struct rpc_task * task,void * calldata)46 static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
47 {
48 struct nfs_unlinkdata *data = calldata;
49 struct inode *dir = d_inode(data->dentry->d_parent);
50
51 trace_nfs_sillyrename_unlink(data, task->tk_status);
52 if (!NFS_PROTO(dir)->unlink_done(task, dir))
53 rpc_restart_call_prepare(task);
54 }
55
56 /**
57 * nfs_async_unlink_release - Release the sillydelete data.
58 * @calldata: struct nfs_unlinkdata to release
59 *
60 * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
61 * rpc_task would be freed too.
62 */
nfs_async_unlink_release(void * calldata)63 static void nfs_async_unlink_release(void *calldata)
64 {
65 struct nfs_unlinkdata *data = calldata;
66 struct dentry *dentry = data->dentry;
67 struct super_block *sb = dentry->d_sb;
68
69 up_read_non_owner(&NFS_I(d_inode(dentry->d_parent))->rmdir_sem);
70 d_lookup_done(dentry);
71 nfs_free_unlinkdata(data);
72 dput(dentry);
73 nfs_sb_deactive(sb);
74 }
75
nfs_unlink_prepare(struct rpc_task * task,void * calldata)76 static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
77 {
78 struct nfs_unlinkdata *data = calldata;
79 struct inode *dir = d_inode(data->dentry->d_parent);
80 NFS_PROTO(dir)->unlink_rpc_prepare(task, data);
81 }
82
83 static const struct rpc_call_ops nfs_unlink_ops = {
84 .rpc_call_done = nfs_async_unlink_done,
85 .rpc_release = nfs_async_unlink_release,
86 .rpc_call_prepare = nfs_unlink_prepare,
87 };
88
nfs_do_call_unlink(struct inode * inode,struct nfs_unlinkdata * data)89 static void nfs_do_call_unlink(struct inode *inode, struct nfs_unlinkdata *data)
90 {
91 struct rpc_message msg = {
92 .rpc_argp = &data->args,
93 .rpc_resp = &data->res,
94 .rpc_cred = data->cred,
95 };
96 struct rpc_task_setup task_setup_data = {
97 .rpc_message = &msg,
98 .callback_ops = &nfs_unlink_ops,
99 .callback_data = data,
100 .workqueue = nfsiod_workqueue,
101 .flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF,
102 };
103 struct rpc_task *task;
104 struct inode *dir = d_inode(data->dentry->d_parent);
105
106 if (nfs_server_capable(inode, NFS_CAP_MOVEABLE))
107 task_setup_data.flags |= RPC_TASK_MOVEABLE;
108
109 nfs_sb_active(dir->i_sb);
110 data->args.fh = NFS_FH(dir);
111 nfs_fattr_init(data->res.dir_attr);
112
113 NFS_PROTO(dir)->unlink_setup(&msg, data->dentry, inode);
114
115 task_setup_data.rpc_client = NFS_CLIENT(dir);
116 task = rpc_run_task(&task_setup_data);
117 if (!IS_ERR(task))
118 rpc_put_task_async(task);
119 }
120
nfs_call_unlink(struct dentry * dentry,struct inode * inode,struct nfs_unlinkdata * data)121 static int nfs_call_unlink(struct dentry *dentry, struct inode *inode, struct nfs_unlinkdata *data)
122 {
123 struct inode *dir = d_inode(dentry->d_parent);
124 struct dentry *alias;
125
126 down_read_non_owner(&NFS_I(dir)->rmdir_sem);
127 alias = d_alloc_parallel(dentry->d_parent, &data->args.name, &data->wq);
128 if (IS_ERR(alias)) {
129 up_read_non_owner(&NFS_I(dir)->rmdir_sem);
130 return 0;
131 }
132 if (!d_in_lookup(alias)) {
133 int ret;
134 void *devname_garbage = NULL;
135
136 /*
137 * Hey, we raced with lookup... See if we need to transfer
138 * the sillyrename information to the aliased dentry.
139 */
140 spin_lock(&alias->d_lock);
141 if (d_really_is_positive(alias) &&
142 !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
143 devname_garbage = alias->d_fsdata;
144 alias->d_fsdata = data;
145 alias->d_flags |= DCACHE_NFSFS_RENAMED;
146 ret = 1;
147 } else
148 ret = 0;
149 spin_unlock(&alias->d_lock);
150 dput(alias);
151 up_read_non_owner(&NFS_I(dir)->rmdir_sem);
152 /*
153 * If we'd displaced old cached devname, free it. At that
154 * point dentry is definitely not a root, so we won't need
155 * that anymore.
156 */
157 kfree(devname_garbage);
158 return ret;
159 }
160 data->dentry = alias;
161 nfs_do_call_unlink(inode, data);
162 return 1;
163 }
164
165 /**
166 * nfs_async_unlink - asynchronous unlinking of a file
167 * @dentry: parent directory of dentry
168 * @name: name of dentry to unlink
169 */
170 static int
nfs_async_unlink(struct dentry * dentry,const struct qstr * name)171 nfs_async_unlink(struct dentry *dentry, const struct qstr *name)
172 {
173 struct nfs_unlinkdata *data;
174 int status = -ENOMEM;
175 void *devname_garbage = NULL;
176
177 data = kzalloc(sizeof(*data), GFP_KERNEL);
178 if (data == NULL)
179 goto out;
180 data->args.name.name = kstrdup(name->name, GFP_KERNEL);
181 if (!data->args.name.name)
182 goto out_free;
183 data->args.name.len = name->len;
184
185 data->cred = get_current_cred();
186 data->res.dir_attr = &data->dir_attr;
187 init_waitqueue_head(&data->wq);
188
189 status = -EBUSY;
190 spin_lock(&dentry->d_lock);
191 if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
192 goto out_unlock;
193 dentry->d_flags |= DCACHE_NFSFS_RENAMED;
194 devname_garbage = dentry->d_fsdata;
195 dentry->d_fsdata = data;
196 spin_unlock(&dentry->d_lock);
197 /*
198 * If we'd displaced old cached devname, free it. At that
199 * point dentry is definitely not a root, so we won't need
200 * that anymore.
201 */
202 kfree(devname_garbage);
203 return 0;
204 out_unlock:
205 spin_unlock(&dentry->d_lock);
206 put_cred(data->cred);
207 kfree(data->args.name.name);
208 out_free:
209 kfree(data);
210 out:
211 return status;
212 }
213
214 /**
215 * nfs_complete_unlink - Initialize completion of the sillydelete
216 * @dentry: dentry to delete
217 * @inode: inode
218 *
219 * Since we're most likely to be called by dentry_iput(), we
220 * only use the dentry to find the sillydelete. We then copy the name
221 * into the qstr.
222 */
223 void
nfs_complete_unlink(struct dentry * dentry,struct inode * inode)224 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
225 {
226 struct nfs_unlinkdata *data;
227
228 spin_lock(&dentry->d_lock);
229 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
230 data = dentry->d_fsdata;
231 dentry->d_fsdata = NULL;
232 spin_unlock(&dentry->d_lock);
233
234 if (NFS_STALE(inode) || !nfs_call_unlink(dentry, inode, data))
235 nfs_free_unlinkdata(data);
236 }
237
238 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
239 static void
nfs_cancel_async_unlink(struct dentry * dentry)240 nfs_cancel_async_unlink(struct dentry *dentry)
241 {
242 spin_lock(&dentry->d_lock);
243 if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
244 struct nfs_unlinkdata *data = dentry->d_fsdata;
245
246 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
247 dentry->d_fsdata = NULL;
248 spin_unlock(&dentry->d_lock);
249 nfs_free_unlinkdata(data);
250 return;
251 }
252 spin_unlock(&dentry->d_lock);
253 }
254
255 /**
256 * nfs_async_rename_done - Sillyrename post-processing
257 * @task: rpc_task of the sillyrename
258 * @calldata: nfs_renamedata for the sillyrename
259 *
260 * Do the directory attribute updates and the d_move
261 */
nfs_async_rename_done(struct rpc_task * task,void * calldata)262 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
263 {
264 struct nfs_renamedata *data = calldata;
265 struct inode *old_dir = data->old_dir;
266 struct inode *new_dir = data->new_dir;
267 struct dentry *old_dentry = data->old_dentry;
268
269 trace_nfs_sillyrename_rename(old_dir, old_dentry,
270 new_dir, data->new_dentry, task->tk_status);
271 if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
272 rpc_restart_call_prepare(task);
273 return;
274 }
275
276 if (data->complete)
277 data->complete(task, data);
278 }
279
280 /**
281 * nfs_async_rename_release - Release the sillyrename data.
282 * @calldata: the struct nfs_renamedata to be released
283 */
nfs_async_rename_release(void * calldata)284 static void nfs_async_rename_release(void *calldata)
285 {
286 struct nfs_renamedata *data = calldata;
287 struct super_block *sb = data->old_dir->i_sb;
288
289 if (d_really_is_positive(data->old_dentry))
290 nfs_mark_for_revalidate(d_inode(data->old_dentry));
291
292 /* The result of the rename is unknown. Play it safe by
293 * forcing a new lookup */
294 if (data->cancelled) {
295 spin_lock(&data->old_dir->i_lock);
296 nfs_force_lookup_revalidate(data->old_dir);
297 spin_unlock(&data->old_dir->i_lock);
298 if (data->new_dir != data->old_dir) {
299 spin_lock(&data->new_dir->i_lock);
300 nfs_force_lookup_revalidate(data->new_dir);
301 spin_unlock(&data->new_dir->i_lock);
302 }
303 }
304
305 dput(data->old_dentry);
306 dput(data->new_dentry);
307 iput(data->old_dir);
308 iput(data->new_dir);
309 nfs_sb_deactive(sb);
310 put_cred(data->cred);
311 kfree(data);
312 }
313
nfs_rename_prepare(struct rpc_task * task,void * calldata)314 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
315 {
316 struct nfs_renamedata *data = calldata;
317 NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data);
318 }
319
320 static const struct rpc_call_ops nfs_rename_ops = {
321 .rpc_call_done = nfs_async_rename_done,
322 .rpc_release = nfs_async_rename_release,
323 .rpc_call_prepare = nfs_rename_prepare,
324 };
325
326 /**
327 * nfs_async_rename - perform an asynchronous rename operation
328 * @old_dir: directory that currently holds the dentry to be renamed
329 * @new_dir: target directory for the rename
330 * @old_dentry: original dentry to be renamed
331 * @new_dentry: dentry to which the old_dentry should be renamed
332 * @complete: Function to run on successful completion
333 *
334 * It's expected that valid references to the dentries and inodes are held
335 */
336 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 *))337 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
338 struct dentry *old_dentry, struct dentry *new_dentry,
339 void (*complete)(struct rpc_task *, struct nfs_renamedata *))
340 {
341 struct nfs_renamedata *data;
342 struct rpc_message msg = { };
343 struct rpc_task_setup task_setup_data = {
344 .rpc_message = &msg,
345 .callback_ops = &nfs_rename_ops,
346 .workqueue = nfsiod_workqueue,
347 .rpc_client = NFS_CLIENT(old_dir),
348 .flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF,
349 };
350
351 if (nfs_server_capable(old_dir, NFS_CAP_MOVEABLE) &&
352 nfs_server_capable(new_dir, NFS_CAP_MOVEABLE))
353 task_setup_data.flags |= RPC_TASK_MOVEABLE;
354
355 data = kzalloc(sizeof(*data), GFP_KERNEL);
356 if (data == NULL)
357 return ERR_PTR(-ENOMEM);
358 task_setup_data.task = &data->task;
359 task_setup_data.callback_data = data;
360
361 data->cred = get_current_cred();
362
363 msg.rpc_argp = &data->args;
364 msg.rpc_resp = &data->res;
365 msg.rpc_cred = data->cred;
366
367 /* set up nfs_renamedata */
368 data->old_dir = old_dir;
369 ihold(old_dir);
370 data->new_dir = new_dir;
371 ihold(new_dir);
372 data->old_dentry = dget(old_dentry);
373 data->new_dentry = dget(new_dentry);
374 nfs_fattr_init(&data->old_fattr);
375 nfs_fattr_init(&data->new_fattr);
376 data->complete = complete;
377
378 /* set up nfs_renameargs */
379 data->args.old_dir = NFS_FH(old_dir);
380 data->args.old_name = &old_dentry->d_name;
381 data->args.new_dir = NFS_FH(new_dir);
382 data->args.new_name = &new_dentry->d_name;
383
384 /* set up nfs_renameres */
385 data->res.old_fattr = &data->old_fattr;
386 data->res.new_fattr = &data->new_fattr;
387
388 nfs_sb_active(old_dir->i_sb);
389
390 NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dentry, new_dentry);
391
392 return rpc_run_task(&task_setup_data);
393 }
394
395 /*
396 * Perform tasks needed when a sillyrename is done such as cancelling the
397 * queued async unlink if it failed.
398 */
399 static void
nfs_complete_sillyrename(struct rpc_task * task,struct nfs_renamedata * data)400 nfs_complete_sillyrename(struct rpc_task *task, struct nfs_renamedata *data)
401 {
402 struct dentry *dentry = data->old_dentry;
403
404 if (task->tk_status != 0) {
405 nfs_cancel_async_unlink(dentry);
406 return;
407 }
408 }
409
410 #define SILLYNAME_PREFIX ".nfs"
411 #define SILLYNAME_PREFIX_LEN ((unsigned)sizeof(SILLYNAME_PREFIX) - 1)
412 #define SILLYNAME_FILEID_LEN ((unsigned)sizeof(u64) << 1)
413 #define SILLYNAME_COUNTER_LEN ((unsigned)sizeof(unsigned int) << 1)
414 #define SILLYNAME_LEN (SILLYNAME_PREFIX_LEN + \
415 SILLYNAME_FILEID_LEN + \
416 SILLYNAME_COUNTER_LEN)
417
418 /**
419 * nfs_sillyrename - Perform a silly-rename of a dentry
420 * @dir: inode of directory that contains dentry
421 * @dentry: dentry to be sillyrenamed
422 *
423 * NFSv2/3 is stateless and the server doesn't know when the client is
424 * holding a file open. To prevent application problems when a file is
425 * unlinked while it's still open, the client performs a "silly-rename".
426 * That is, it renames the file to a hidden file in the same directory,
427 * and only performs the unlink once the last reference to it is put.
428 *
429 * The final cleanup is done during dentry_iput.
430 *
431 * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
432 * could take responsibility for keeping open files referenced. The server
433 * would also need to ensure that opened-but-deleted files were kept over
434 * reboots. However, we may not assume a server does so. (RFC 5661
435 * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
436 * use to advertise that it does this; some day we may take advantage of
437 * it.))
438 */
439 int
nfs_sillyrename(struct inode * dir,struct dentry * dentry)440 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
441 {
442 static unsigned int sillycounter;
443 unsigned char silly[SILLYNAME_LEN + 1];
444 unsigned long long fileid;
445 struct dentry *sdentry;
446 struct inode *inode = d_inode(dentry);
447 struct rpc_task *task;
448 int error = -EBUSY;
449
450 dfprintk(VFS, "NFS: silly-rename(%pd2, ct=%d)\n",
451 dentry, d_count(dentry));
452 nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
453
454 /*
455 * We don't allow a dentry to be silly-renamed twice.
456 */
457 if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
458 goto out;
459
460 fileid = NFS_FILEID(d_inode(dentry));
461
462 sdentry = NULL;
463 do {
464 int slen;
465 dput(sdentry);
466 sillycounter++;
467 slen = scnprintf(silly, sizeof(silly),
468 SILLYNAME_PREFIX "%0*llx%0*x",
469 SILLYNAME_FILEID_LEN, fileid,
470 SILLYNAME_COUNTER_LEN, sillycounter);
471
472 dfprintk(VFS, "NFS: trying to rename %pd to %s\n",
473 dentry, silly);
474
475 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
476 /*
477 * N.B. Better to return EBUSY here ... it could be
478 * dangerous to delete the file while it's in use.
479 */
480 if (IS_ERR(sdentry))
481 goto out;
482 } while (d_inode(sdentry) != NULL); /* need negative lookup */
483
484 ihold(inode);
485
486 /* queue unlink first. Can't do this from rpc_release as it
487 * has to allocate memory
488 */
489 error = nfs_async_unlink(dentry, &sdentry->d_name);
490 if (error)
491 goto out_dput;
492
493 /* run the rename task, undo unlink if it fails */
494 task = nfs_async_rename(dir, dir, dentry, sdentry,
495 nfs_complete_sillyrename);
496 if (IS_ERR(task)) {
497 error = -EBUSY;
498 nfs_cancel_async_unlink(dentry);
499 goto out_dput;
500 }
501
502 /* wait for the RPC task to complete, unless a SIGKILL intervenes */
503 error = rpc_wait_for_completion_task(task);
504 if (error == 0)
505 error = task->tk_status;
506 switch (error) {
507 case 0:
508 /* The rename succeeded */
509 nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
510 spin_lock(&inode->i_lock);
511 NFS_I(inode)->attr_gencount = nfs_inc_attr_generation_counter();
512 nfs_set_cache_invalid(inode, NFS_INO_INVALID_CHANGE |
513 NFS_INO_INVALID_CTIME |
514 NFS_INO_REVAL_FORCED);
515 spin_unlock(&inode->i_lock);
516 d_move(dentry, sdentry);
517 break;
518 case -ERESTARTSYS:
519 /* The result of the rename is unknown. Play it safe by
520 * forcing a new lookup */
521 d_drop(dentry);
522 d_drop(sdentry);
523 }
524 rpc_put_task(task);
525 out_dput:
526 iput(inode);
527 dput(sdentry);
528 out:
529 return error;
530 }
531