Merge branch 'for-4.1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj...
[firefly-linux-kernel-4.4.55.git] / fs / nfs / unlink.c
1 /*
2  *  linux/fs/nfs/unlink.c
3  *
4  * nfs sillydelete handling
5  *
6  */
7
8 #include <linux/slab.h>
9 #include <linux/string.h>
10 #include <linux/dcache.h>
11 #include <linux/sunrpc/sched.h>
12 #include <linux/sunrpc/clnt.h>
13 #include <linux/nfs_fs.h>
14 #include <linux/sched.h>
15 #include <linux/wait.h>
16 #include <linux/namei.h>
17 #include <linux/fsnotify.h>
18
19 #include "internal.h"
20 #include "nfs4_fs.h"
21 #include "iostat.h"
22 #include "delegation.h"
23
24 #include "nfstrace.h"
25
26 /**
27  * nfs_free_unlinkdata - release data from a sillydelete operation.
28  * @data: pointer to unlink structure.
29  */
30 static void
31 nfs_free_unlinkdata(struct nfs_unlinkdata *data)
32 {
33         iput(data->dir);
34         put_rpccred(data->cred);
35         kfree(data->args.name.name);
36         kfree(data);
37 }
38
39 #define NAME_ALLOC_LEN(len)     ((len+16) & ~15)
40 /**
41  * nfs_copy_dname - copy dentry name to data structure
42  * @dentry: pointer to dentry
43  * @data: nfs_unlinkdata
44  */
45 static int nfs_copy_dname(struct dentry *dentry, struct nfs_unlinkdata *data)
46 {
47         char            *str;
48         int             len = dentry->d_name.len;
49
50         str = kmemdup(dentry->d_name.name, NAME_ALLOC_LEN(len), GFP_KERNEL);
51         if (!str)
52                 return -ENOMEM;
53         data->args.name.len = len;
54         data->args.name.name = str;
55         return 0;
56 }
57
58 static void nfs_free_dname(struct nfs_unlinkdata *data)
59 {
60         kfree(data->args.name.name);
61         data->args.name.name = NULL;
62         data->args.name.len = 0;
63 }
64
65 static void nfs_dec_sillycount(struct inode *dir)
66 {
67         struct nfs_inode *nfsi = NFS_I(dir);
68         if (atomic_dec_return(&nfsi->silly_count) == 1)
69                 wake_up(&nfsi->waitqueue);
70 }
71
72 /**
73  * nfs_async_unlink_done - Sillydelete post-processing
74  * @task: rpc_task of the sillydelete
75  *
76  * Do the directory attribute update.
77  */
78 static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
79 {
80         struct nfs_unlinkdata *data = calldata;
81         struct inode *dir = data->dir;
82
83         trace_nfs_sillyrename_unlink(data, task->tk_status);
84         if (!NFS_PROTO(dir)->unlink_done(task, dir))
85                 rpc_restart_call_prepare(task);
86 }
87
88 /**
89  * nfs_async_unlink_release - Release the sillydelete data.
90  * @task: rpc_task of the sillydelete
91  *
92  * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
93  * rpc_task would be freed too.
94  */
95 static void nfs_async_unlink_release(void *calldata)
96 {
97         struct nfs_unlinkdata   *data = calldata;
98         struct super_block *sb = data->dir->i_sb;
99
100         nfs_dec_sillycount(data->dir);
101         nfs_free_unlinkdata(data);
102         nfs_sb_deactive(sb);
103 }
104
105 static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
106 {
107         struct nfs_unlinkdata *data = calldata;
108         NFS_PROTO(data->dir)->unlink_rpc_prepare(task, data);
109 }
110
111 static const struct rpc_call_ops nfs_unlink_ops = {
112         .rpc_call_done = nfs_async_unlink_done,
113         .rpc_release = nfs_async_unlink_release,
114         .rpc_call_prepare = nfs_unlink_prepare,
115 };
116
117 static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct nfs_unlinkdata *data)
118 {
119         struct rpc_message msg = {
120                 .rpc_argp = &data->args,
121                 .rpc_resp = &data->res,
122                 .rpc_cred = data->cred,
123         };
124         struct rpc_task_setup task_setup_data = {
125                 .rpc_message = &msg,
126                 .callback_ops = &nfs_unlink_ops,
127                 .callback_data = data,
128                 .workqueue = nfsiod_workqueue,
129                 .flags = RPC_TASK_ASYNC,
130         };
131         struct rpc_task *task;
132         struct dentry *alias;
133
134         alias = d_lookup(parent, &data->args.name);
135         if (alias != NULL) {
136                 int ret;
137                 void *devname_garbage = NULL;
138
139                 /*
140                  * Hey, we raced with lookup... See if we need to transfer
141                  * the sillyrename information to the aliased dentry.
142                  */
143                 nfs_free_dname(data);
144                 ret = nfs_copy_dname(alias, data);
145                 spin_lock(&alias->d_lock);
146                 if (ret == 0 && d_really_is_positive(alias) &&
147                     !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
148                         devname_garbage = alias->d_fsdata;
149                         alias->d_fsdata = data;
150                         alias->d_flags |= DCACHE_NFSFS_RENAMED;
151                         ret = 1;
152                 } else
153                         ret = 0;
154                 spin_unlock(&alias->d_lock);
155                 nfs_dec_sillycount(dir);
156                 dput(alias);
157                 /*
158                  * If we'd displaced old cached devname, free it.  At that
159                  * point dentry is definitely not a root, so we won't need
160                  * that anymore.
161                  */
162                 kfree(devname_garbage);
163                 return ret;
164         }
165         data->dir = igrab(dir);
166         if (!data->dir) {
167                 nfs_dec_sillycount(dir);
168                 return 0;
169         }
170         nfs_sb_active(dir->i_sb);
171         data->args.fh = NFS_FH(dir);
172         nfs_fattr_init(data->res.dir_attr);
173
174         NFS_PROTO(dir)->unlink_setup(&msg, dir);
175
176         task_setup_data.rpc_client = NFS_CLIENT(dir);
177         task = rpc_run_task(&task_setup_data);
178         if (!IS_ERR(task))
179                 rpc_put_task_async(task);
180         return 1;
181 }
182
183 static int nfs_call_unlink(struct dentry *dentry, struct nfs_unlinkdata *data)
184 {
185         struct dentry *parent;
186         struct inode *dir;
187         int ret = 0;
188
189
190         parent = dget_parent(dentry);
191         if (parent == NULL)
192                 goto out_free;
193         dir = d_inode(parent);
194         /* Non-exclusive lock protects against concurrent lookup() calls */
195         spin_lock(&dir->i_lock);
196         if (atomic_inc_not_zero(&NFS_I(dir)->silly_count) == 0) {
197                 /* Deferred delete */
198                 hlist_add_head(&data->list, &NFS_I(dir)->silly_list);
199                 spin_unlock(&dir->i_lock);
200                 ret = 1;
201                 goto out_dput;
202         }
203         spin_unlock(&dir->i_lock);
204         ret = nfs_do_call_unlink(parent, dir, data);
205 out_dput:
206         dput(parent);
207 out_free:
208         return ret;
209 }
210
211 void nfs_wait_on_sillyrename(struct dentry *dentry)
212 {
213         struct nfs_inode *nfsi = NFS_I(d_inode(dentry));
214
215         wait_event(nfsi->waitqueue, atomic_read(&nfsi->silly_count) <= 1);
216 }
217
218 void nfs_block_sillyrename(struct dentry *dentry)
219 {
220         struct nfs_inode *nfsi = NFS_I(d_inode(dentry));
221
222         wait_event(nfsi->waitqueue, atomic_cmpxchg(&nfsi->silly_count, 1, 0) == 1);
223 }
224
225 void nfs_unblock_sillyrename(struct dentry *dentry)
226 {
227         struct inode *dir = d_inode(dentry);
228         struct nfs_inode *nfsi = NFS_I(dir);
229         struct nfs_unlinkdata *data;
230
231         atomic_inc(&nfsi->silly_count);
232         spin_lock(&dir->i_lock);
233         while (!hlist_empty(&nfsi->silly_list)) {
234                 if (!atomic_inc_not_zero(&nfsi->silly_count))
235                         break;
236                 data = hlist_entry(nfsi->silly_list.first, struct nfs_unlinkdata, list);
237                 hlist_del(&data->list);
238                 spin_unlock(&dir->i_lock);
239                 if (nfs_do_call_unlink(dentry, dir, data) == 0)
240                         nfs_free_unlinkdata(data);
241                 spin_lock(&dir->i_lock);
242         }
243         spin_unlock(&dir->i_lock);
244 }
245
246 /**
247  * nfs_async_unlink - asynchronous unlinking of a file
248  * @dir: parent directory of dentry
249  * @dentry: dentry to unlink
250  */
251 static int
252 nfs_async_unlink(struct inode *dir, struct dentry *dentry)
253 {
254         struct nfs_unlinkdata *data;
255         int status = -ENOMEM;
256         void *devname_garbage = NULL;
257
258         data = kzalloc(sizeof(*data), GFP_KERNEL);
259         if (data == NULL)
260                 goto out;
261
262         data->cred = rpc_lookup_cred();
263         if (IS_ERR(data->cred)) {
264                 status = PTR_ERR(data->cred);
265                 goto out_free;
266         }
267         data->res.dir_attr = &data->dir_attr;
268
269         status = -EBUSY;
270         spin_lock(&dentry->d_lock);
271         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
272                 goto out_unlock;
273         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
274         devname_garbage = dentry->d_fsdata;
275         dentry->d_fsdata = data;
276         spin_unlock(&dentry->d_lock);
277         /*
278          * If we'd displaced old cached devname, free it.  At that
279          * point dentry is definitely not a root, so we won't need
280          * that anymore.
281          */
282         kfree(devname_garbage);
283         return 0;
284 out_unlock:
285         spin_unlock(&dentry->d_lock);
286         put_rpccred(data->cred);
287 out_free:
288         kfree(data);
289 out:
290         return status;
291 }
292
293 /**
294  * nfs_complete_unlink - Initialize completion of the sillydelete
295  * @dentry: dentry to delete
296  * @inode: inode
297  *
298  * Since we're most likely to be called by dentry_iput(), we
299  * only use the dentry to find the sillydelete. We then copy the name
300  * into the qstr.
301  */
302 void
303 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
304 {
305         struct nfs_unlinkdata   *data = NULL;
306
307         spin_lock(&dentry->d_lock);
308         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
309                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
310                 data = dentry->d_fsdata;
311                 dentry->d_fsdata = NULL;
312         }
313         spin_unlock(&dentry->d_lock);
314
315         if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
316                 nfs_free_unlinkdata(data);
317 }
318
319 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
320 static void
321 nfs_cancel_async_unlink(struct dentry *dentry)
322 {
323         spin_lock(&dentry->d_lock);
324         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
325                 struct nfs_unlinkdata *data = dentry->d_fsdata;
326
327                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
328                 dentry->d_fsdata = NULL;
329                 spin_unlock(&dentry->d_lock);
330                 nfs_free_unlinkdata(data);
331                 return;
332         }
333         spin_unlock(&dentry->d_lock);
334 }
335
336 /**
337  * nfs_async_rename_done - Sillyrename post-processing
338  * @task: rpc_task of the sillyrename
339  * @calldata: nfs_renamedata for the sillyrename
340  *
341  * Do the directory attribute updates and the d_move
342  */
343 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
344 {
345         struct nfs_renamedata *data = calldata;
346         struct inode *old_dir = data->old_dir;
347         struct inode *new_dir = data->new_dir;
348         struct dentry *old_dentry = data->old_dentry;
349
350         trace_nfs_sillyrename_rename(old_dir, old_dentry,
351                         new_dir, data->new_dentry, task->tk_status);
352         if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
353                 rpc_restart_call_prepare(task);
354                 return;
355         }
356
357         if (data->complete)
358                 data->complete(task, data);
359 }
360
361 /**
362  * nfs_async_rename_release - Release the sillyrename data.
363  * @calldata: the struct nfs_renamedata to be released
364  */
365 static void nfs_async_rename_release(void *calldata)
366 {
367         struct nfs_renamedata   *data = calldata;
368         struct super_block *sb = data->old_dir->i_sb;
369
370         if (d_really_is_positive(data->old_dentry))
371                 nfs_mark_for_revalidate(d_inode(data->old_dentry));
372
373         dput(data->old_dentry);
374         dput(data->new_dentry);
375         iput(data->old_dir);
376         iput(data->new_dir);
377         nfs_sb_deactive(sb);
378         put_rpccred(data->cred);
379         kfree(data);
380 }
381
382 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
383 {
384         struct nfs_renamedata *data = calldata;
385         NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data);
386 }
387
388 static const struct rpc_call_ops nfs_rename_ops = {
389         .rpc_call_done = nfs_async_rename_done,
390         .rpc_release = nfs_async_rename_release,
391         .rpc_call_prepare = nfs_rename_prepare,
392 };
393
394 /**
395  * nfs_async_rename - perform an asynchronous rename operation
396  * @old_dir: directory that currently holds the dentry to be renamed
397  * @new_dir: target directory for the rename
398  * @old_dentry: original dentry to be renamed
399  * @new_dentry: dentry to which the old_dentry should be renamed
400  *
401  * It's expected that valid references to the dentries and inodes are held
402  */
403 struct rpc_task *
404 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
405                  struct dentry *old_dentry, struct dentry *new_dentry,
406                  void (*complete)(struct rpc_task *, struct nfs_renamedata *))
407 {
408         struct nfs_renamedata *data;
409         struct rpc_message msg = { };
410         struct rpc_task_setup task_setup_data = {
411                 .rpc_message = &msg,
412                 .callback_ops = &nfs_rename_ops,
413                 .workqueue = nfsiod_workqueue,
414                 .rpc_client = NFS_CLIENT(old_dir),
415                 .flags = RPC_TASK_ASYNC,
416         };
417
418         data = kzalloc(sizeof(*data), GFP_KERNEL);
419         if (data == NULL)
420                 return ERR_PTR(-ENOMEM);
421         task_setup_data.callback_data = data;
422
423         data->cred = rpc_lookup_cred();
424         if (IS_ERR(data->cred)) {
425                 struct rpc_task *task = ERR_CAST(data->cred);
426                 kfree(data);
427                 return task;
428         }
429
430         msg.rpc_argp = &data->args;
431         msg.rpc_resp = &data->res;
432         msg.rpc_cred = data->cred;
433
434         /* set up nfs_renamedata */
435         data->old_dir = old_dir;
436         ihold(old_dir);
437         data->new_dir = new_dir;
438         ihold(new_dir);
439         data->old_dentry = dget(old_dentry);
440         data->new_dentry = dget(new_dentry);
441         nfs_fattr_init(&data->old_fattr);
442         nfs_fattr_init(&data->new_fattr);
443         data->complete = complete;
444
445         /* set up nfs_renameargs */
446         data->args.old_dir = NFS_FH(old_dir);
447         data->args.old_name = &old_dentry->d_name;
448         data->args.new_dir = NFS_FH(new_dir);
449         data->args.new_name = &new_dentry->d_name;
450
451         /* set up nfs_renameres */
452         data->res.old_fattr = &data->old_fattr;
453         data->res.new_fattr = &data->new_fattr;
454
455         nfs_sb_active(old_dir->i_sb);
456
457         NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dir);
458
459         return rpc_run_task(&task_setup_data);
460 }
461
462 /*
463  * Perform tasks needed when a sillyrename is done such as cancelling the
464  * queued async unlink if it failed.
465  */
466 static void
467 nfs_complete_sillyrename(struct rpc_task *task, struct nfs_renamedata *data)
468 {
469         struct dentry *dentry = data->old_dentry;
470
471         if (task->tk_status != 0) {
472                 nfs_cancel_async_unlink(dentry);
473                 return;
474         }
475
476         /*
477          * vfs_unlink and the like do not issue this when a file is
478          * sillyrenamed, so do it here.
479          */
480         fsnotify_nameremove(dentry, 0);
481 }
482
483 #define SILLYNAME_PREFIX ".nfs"
484 #define SILLYNAME_PREFIX_LEN ((unsigned)sizeof(SILLYNAME_PREFIX) - 1)
485 #define SILLYNAME_FILEID_LEN ((unsigned)sizeof(u64) << 1)
486 #define SILLYNAME_COUNTER_LEN ((unsigned)sizeof(unsigned int) << 1)
487 #define SILLYNAME_LEN (SILLYNAME_PREFIX_LEN + \
488                 SILLYNAME_FILEID_LEN + \
489                 SILLYNAME_COUNTER_LEN)
490
491 /**
492  * nfs_sillyrename - Perform a silly-rename of a dentry
493  * @dir: inode of directory that contains dentry
494  * @dentry: dentry to be sillyrenamed
495  *
496  * NFSv2/3 is stateless and the server doesn't know when the client is
497  * holding a file open. To prevent application problems when a file is
498  * unlinked while it's still open, the client performs a "silly-rename".
499  * That is, it renames the file to a hidden file in the same directory,
500  * and only performs the unlink once the last reference to it is put.
501  *
502  * The final cleanup is done during dentry_iput.
503  *
504  * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
505  * could take responsibility for keeping open files referenced.  The server
506  * would also need to ensure that opened-but-deleted files were kept over
507  * reboots.  However, we may not assume a server does so.  (RFC 5661
508  * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
509  * use to advertise that it does this; some day we may take advantage of
510  * it.))
511  */
512 int
513 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
514 {
515         static unsigned int sillycounter;
516         unsigned char silly[SILLYNAME_LEN + 1];
517         unsigned long long fileid;
518         struct dentry *sdentry;
519         struct rpc_task *task;
520         int            error = -EBUSY;
521
522         dfprintk(VFS, "NFS: silly-rename(%pd2, ct=%d)\n",
523                 dentry, d_count(dentry));
524         nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
525
526         /*
527          * We don't allow a dentry to be silly-renamed twice.
528          */
529         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
530                 goto out;
531
532         fileid = NFS_FILEID(d_inode(dentry));
533
534         /* Return delegation in anticipation of the rename */
535         NFS_PROTO(d_inode(dentry))->return_delegation(d_inode(dentry));
536
537         sdentry = NULL;
538         do {
539                 int slen;
540                 dput(sdentry);
541                 sillycounter++;
542                 slen = scnprintf(silly, sizeof(silly),
543                                 SILLYNAME_PREFIX "%0*llx%0*x",
544                                 SILLYNAME_FILEID_LEN, fileid,
545                                 SILLYNAME_COUNTER_LEN, sillycounter);
546
547                 dfprintk(VFS, "NFS: trying to rename %pd to %s\n",
548                                 dentry, silly);
549
550                 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
551                 /*
552                  * N.B. Better to return EBUSY here ... it could be
553                  * dangerous to delete the file while it's in use.
554                  */
555                 if (IS_ERR(sdentry))
556                         goto out;
557         } while (d_inode(sdentry) != NULL); /* need negative lookup */
558
559         /* queue unlink first. Can't do this from rpc_release as it
560          * has to allocate memory
561          */
562         error = nfs_async_unlink(dir, dentry);
563         if (error)
564                 goto out_dput;
565
566         /* populate unlinkdata with the right dname */
567         error = nfs_copy_dname(sdentry,
568                                 (struct nfs_unlinkdata *)dentry->d_fsdata);
569         if (error) {
570                 nfs_cancel_async_unlink(dentry);
571                 goto out_dput;
572         }
573
574         /* run the rename task, undo unlink if it fails */
575         task = nfs_async_rename(dir, dir, dentry, sdentry,
576                                         nfs_complete_sillyrename);
577         if (IS_ERR(task)) {
578                 error = -EBUSY;
579                 nfs_cancel_async_unlink(dentry);
580                 goto out_dput;
581         }
582
583         /* wait for the RPC task to complete, unless a SIGKILL intervenes */
584         error = rpc_wait_for_completion_task(task);
585         if (error == 0)
586                 error = task->tk_status;
587         switch (error) {
588         case 0:
589                 /* The rename succeeded */
590                 nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
591                 d_move(dentry, sdentry);
592                 break;
593         case -ERESTARTSYS:
594                 /* The result of the rename is unknown. Play it safe by
595                  * forcing a new lookup */
596                 d_drop(dentry);
597                 d_drop(sdentry);
598         }
599         rpc_put_task(task);
600 out_dput:
601         dput(sdentry);
602 out:
603         return error;
604 }