9697cd5d2561c3064bf4d16f7b05aa92b87e34a1
[releases.git] / unlink.c
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
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  */
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  */
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
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
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
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
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
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
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  */
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  */
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
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 *
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
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
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 }