nfs: don't use d_move in nfs_async_rename_done
[linux-2.6.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
18 #include "internal.h"
19 #include "nfs4_fs.h"
20 #include "iostat.h"
21 #include "delegation.h"
22
23 struct nfs_unlinkdata {
24         struct hlist_node list;
25         struct nfs_removeargs args;
26         struct nfs_removeres res;
27         struct inode *dir;
28         struct rpc_cred *cred;
29         struct nfs_fattr dir_attr;
30 };
31
32 /**
33  * nfs_free_unlinkdata - release data from a sillydelete operation.
34  * @data: pointer to unlink structure.
35  */
36 static void
37 nfs_free_unlinkdata(struct nfs_unlinkdata *data)
38 {
39         iput(data->dir);
40         put_rpccred(data->cred);
41         kfree(data->args.name.name);
42         kfree(data);
43 }
44
45 #define NAME_ALLOC_LEN(len)     ((len+16) & ~15)
46 /**
47  * nfs_copy_dname - copy dentry name to data structure
48  * @dentry: pointer to dentry
49  * @data: nfs_unlinkdata
50  */
51 static int nfs_copy_dname(struct dentry *dentry, struct nfs_unlinkdata *data)
52 {
53         char            *str;
54         int             len = dentry->d_name.len;
55
56         str = kmemdup(dentry->d_name.name, NAME_ALLOC_LEN(len), GFP_KERNEL);
57         if (!str)
58                 return -ENOMEM;
59         data->args.name.len = len;
60         data->args.name.name = str;
61         return 0;
62 }
63
64 static void nfs_free_dname(struct nfs_unlinkdata *data)
65 {
66         kfree(data->args.name.name);
67         data->args.name.name = NULL;
68         data->args.name.len = 0;
69 }
70
71 static void nfs_dec_sillycount(struct inode *dir)
72 {
73         struct nfs_inode *nfsi = NFS_I(dir);
74         if (atomic_dec_return(&nfsi->silly_count) == 1)
75                 wake_up(&nfsi->waitqueue);
76 }
77
78 /**
79  * nfs_async_unlink_done - Sillydelete post-processing
80  * @task: rpc_task of the sillydelete
81  *
82  * Do the directory attribute update.
83  */
84 static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
85 {
86         struct nfs_unlinkdata *data = calldata;
87         struct inode *dir = data->dir;
88
89         if (!NFS_PROTO(dir)->unlink_done(task, dir))
90                 nfs_restart_rpc(task, NFS_SERVER(dir)->nfs_client);
91 }
92
93 /**
94  * nfs_async_unlink_release - Release the sillydelete data.
95  * @task: rpc_task of the sillydelete
96  *
97  * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
98  * rpc_task would be freed too.
99  */
100 static void nfs_async_unlink_release(void *calldata)
101 {
102         struct nfs_unlinkdata   *data = calldata;
103         struct super_block *sb = data->dir->i_sb;
104
105         nfs_dec_sillycount(data->dir);
106         nfs_free_unlinkdata(data);
107         nfs_sb_deactive(sb);
108 }
109
110 #if defined(CONFIG_NFS_V4_1)
111 void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
112 {
113         struct nfs_unlinkdata *data = calldata;
114         struct nfs_server *server = NFS_SERVER(data->dir);
115
116         if (nfs4_setup_sequence(server, &data->args.seq_args,
117                                 &data->res.seq_res, 1, task))
118                 return;
119         rpc_call_start(task);
120 }
121 #endif /* CONFIG_NFS_V4_1 */
122
123 static const struct rpc_call_ops nfs_unlink_ops = {
124         .rpc_call_done = nfs_async_unlink_done,
125         .rpc_release = nfs_async_unlink_release,
126 #if defined(CONFIG_NFS_V4_1)
127         .rpc_call_prepare = nfs_unlink_prepare,
128 #endif /* CONFIG_NFS_V4_1 */
129 };
130
131 static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct nfs_unlinkdata *data)
132 {
133         struct rpc_message msg = {
134                 .rpc_argp = &data->args,
135                 .rpc_resp = &data->res,
136                 .rpc_cred = data->cred,
137         };
138         struct rpc_task_setup task_setup_data = {
139                 .rpc_message = &msg,
140                 .callback_ops = &nfs_unlink_ops,
141                 .callback_data = data,
142                 .workqueue = nfsiod_workqueue,
143                 .flags = RPC_TASK_ASYNC,
144         };
145         struct rpc_task *task;
146         struct dentry *alias;
147
148         alias = d_lookup(parent, &data->args.name);
149         if (alias != NULL) {
150                 int ret;
151                 void *devname_garbage = NULL;
152
153                 /*
154                  * Hey, we raced with lookup... See if we need to transfer
155                  * the sillyrename information to the aliased dentry.
156                  */
157                 nfs_free_dname(data);
158                 ret = nfs_copy_dname(alias, data);
159                 spin_lock(&alias->d_lock);
160                 if (ret == 0 && alias->d_inode != NULL &&
161                     !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
162                         devname_garbage = alias->d_fsdata;
163                         alias->d_fsdata = data;
164                         alias->d_flags |= DCACHE_NFSFS_RENAMED;
165                         ret = 1;
166                 } else
167                         ret = 0;
168                 spin_unlock(&alias->d_lock);
169                 nfs_dec_sillycount(dir);
170                 dput(alias);
171                 /*
172                  * If we'd displaced old cached devname, free it.  At that
173                  * point dentry is definitely not a root, so we won't need
174                  * that anymore.
175                  */
176                 kfree(devname_garbage);
177                 return ret;
178         }
179         data->dir = igrab(dir);
180         if (!data->dir) {
181                 nfs_dec_sillycount(dir);
182                 return 0;
183         }
184         nfs_sb_active(dir->i_sb);
185         data->args.fh = NFS_FH(dir);
186         nfs_fattr_init(data->res.dir_attr);
187
188         NFS_PROTO(dir)->unlink_setup(&msg, dir);
189
190         task_setup_data.rpc_client = NFS_CLIENT(dir);
191         task = rpc_run_task(&task_setup_data);
192         if (!IS_ERR(task))
193                 rpc_put_task_async(task);
194         return 1;
195 }
196
197 static int nfs_call_unlink(struct dentry *dentry, struct nfs_unlinkdata *data)
198 {
199         struct dentry *parent;
200         struct inode *dir;
201         int ret = 0;
202
203
204         parent = dget_parent(dentry);
205         if (parent == NULL)
206                 goto out_free;
207         dir = parent->d_inode;
208         /* Non-exclusive lock protects against concurrent lookup() calls */
209         spin_lock(&dir->i_lock);
210         if (atomic_inc_not_zero(&NFS_I(dir)->silly_count) == 0) {
211                 /* Deferred delete */
212                 hlist_add_head(&data->list, &NFS_I(dir)->silly_list);
213                 spin_unlock(&dir->i_lock);
214                 ret = 1;
215                 goto out_dput;
216         }
217         spin_unlock(&dir->i_lock);
218         ret = nfs_do_call_unlink(parent, dir, data);
219 out_dput:
220         dput(parent);
221 out_free:
222         return ret;
223 }
224
225 void nfs_block_sillyrename(struct dentry *dentry)
226 {
227         struct nfs_inode *nfsi = NFS_I(dentry->d_inode);
228
229         wait_event(nfsi->waitqueue, atomic_cmpxchg(&nfsi->silly_count, 1, 0) == 1);
230 }
231
232 void nfs_unblock_sillyrename(struct dentry *dentry)
233 {
234         struct inode *dir = dentry->d_inode;
235         struct nfs_inode *nfsi = NFS_I(dir);
236         struct nfs_unlinkdata *data;
237
238         atomic_inc(&nfsi->silly_count);
239         spin_lock(&dir->i_lock);
240         while (!hlist_empty(&nfsi->silly_list)) {
241                 if (!atomic_inc_not_zero(&nfsi->silly_count))
242                         break;
243                 data = hlist_entry(nfsi->silly_list.first, struct nfs_unlinkdata, list);
244                 hlist_del(&data->list);
245                 spin_unlock(&dir->i_lock);
246                 if (nfs_do_call_unlink(dentry, dir, data) == 0)
247                         nfs_free_unlinkdata(data);
248                 spin_lock(&dir->i_lock);
249         }
250         spin_unlock(&dir->i_lock);
251 }
252
253 /**
254  * nfs_async_unlink - asynchronous unlinking of a file
255  * @dir: parent directory of dentry
256  * @dentry: dentry to unlink
257  */
258 static int
259 nfs_async_unlink(struct inode *dir, struct dentry *dentry)
260 {
261         struct nfs_unlinkdata *data;
262         int status = -ENOMEM;
263         void *devname_garbage = NULL;
264
265         data = kzalloc(sizeof(*data), GFP_KERNEL);
266         if (data == NULL)
267                 goto out;
268
269         data->cred = rpc_lookup_cred();
270         if (IS_ERR(data->cred)) {
271                 status = PTR_ERR(data->cred);
272                 goto out_free;
273         }
274         data->res.dir_attr = &data->dir_attr;
275
276         status = -EBUSY;
277         spin_lock(&dentry->d_lock);
278         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
279                 goto out_unlock;
280         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
281         devname_garbage = dentry->d_fsdata;
282         dentry->d_fsdata = data;
283         spin_unlock(&dentry->d_lock);
284         /*
285          * If we'd displaced old cached devname, free it.  At that
286          * point dentry is definitely not a root, so we won't need
287          * that anymore.
288          */
289         if (devname_garbage)
290                 kfree(devname_garbage);
291         return 0;
292 out_unlock:
293         spin_unlock(&dentry->d_lock);
294         put_rpccred(data->cred);
295 out_free:
296         kfree(data);
297 out:
298         return status;
299 }
300
301 /**
302  * nfs_complete_unlink - Initialize completion of the sillydelete
303  * @dentry: dentry to delete
304  * @inode: inode
305  *
306  * Since we're most likely to be called by dentry_iput(), we
307  * only use the dentry to find the sillydelete. We then copy the name
308  * into the qstr.
309  */
310 void
311 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
312 {
313         struct nfs_unlinkdata   *data = NULL;
314
315         spin_lock(&dentry->d_lock);
316         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
317                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
318                 data = dentry->d_fsdata;
319                 dentry->d_fsdata = NULL;
320         }
321         spin_unlock(&dentry->d_lock);
322
323         if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
324                 nfs_free_unlinkdata(data);
325 }
326
327 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
328 static void
329 nfs_cancel_async_unlink(struct dentry *dentry)
330 {
331         spin_lock(&dentry->d_lock);
332         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
333                 struct nfs_unlinkdata *data = dentry->d_fsdata;
334
335                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
336                 dentry->d_fsdata = NULL;
337                 spin_unlock(&dentry->d_lock);
338                 nfs_free_unlinkdata(data);
339                 return;
340         }
341         spin_unlock(&dentry->d_lock);
342 }
343
344 struct nfs_renamedata {
345         struct nfs_renameargs   args;
346         struct nfs_renameres    res;
347         struct rpc_cred         *cred;
348         struct inode            *old_dir;
349         struct dentry           *old_dentry;
350         struct nfs_fattr        old_fattr;
351         struct inode            *new_dir;
352         struct dentry           *new_dentry;
353         struct nfs_fattr        new_fattr;
354 };
355
356 /**
357  * nfs_async_rename_done - Sillyrename post-processing
358  * @task: rpc_task of the sillyrename
359  * @calldata: nfs_renamedata for the sillyrename
360  *
361  * Do the directory attribute updates and the d_move
362  */
363 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
364 {
365         struct nfs_renamedata *data = calldata;
366         struct inode *old_dir = data->old_dir;
367         struct inode *new_dir = data->new_dir;
368         struct dentry *old_dentry = data->old_dentry;
369         struct dentry *new_dentry = data->new_dentry;
370
371         if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
372                 nfs_restart_rpc(task, NFS_SERVER(old_dir)->nfs_client);
373                 return;
374         }
375
376         if (task->tk_status != 0) {
377                 nfs_cancel_async_unlink(old_dentry);
378                 return;
379         }
380
381         d_drop(old_dentry);
382         d_drop(new_dentry);
383 }
384
385 /**
386  * nfs_async_rename_release - Release the sillyrename data.
387  * @calldata: the struct nfs_renamedata to be released
388  */
389 static void nfs_async_rename_release(void *calldata)
390 {
391         struct nfs_renamedata   *data = calldata;
392         struct super_block *sb = data->old_dir->i_sb;
393
394         if (data->old_dentry->d_inode)
395                 nfs_mark_for_revalidate(data->old_dentry->d_inode);
396
397         dput(data->old_dentry);
398         dput(data->new_dentry);
399         iput(data->old_dir);
400         iput(data->new_dir);
401         nfs_sb_deactive(sb);
402         put_rpccred(data->cred);
403         kfree(data);
404 }
405
406 #if defined(CONFIG_NFS_V4_1)
407 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
408 {
409         struct nfs_renamedata *data = calldata;
410         struct nfs_server *server = NFS_SERVER(data->old_dir);
411
412         if (nfs4_setup_sequence(server, &data->args.seq_args,
413                                 &data->res.seq_res, 1, task))
414                 return;
415         rpc_call_start(task);
416 }
417 #endif /* CONFIG_NFS_V4_1 */
418
419 static const struct rpc_call_ops nfs_rename_ops = {
420         .rpc_call_done = nfs_async_rename_done,
421         .rpc_release = nfs_async_rename_release,
422 #if defined(CONFIG_NFS_V4_1)
423         .rpc_call_prepare = nfs_rename_prepare,
424 #endif /* CONFIG_NFS_V4_1 */
425 };
426
427 /**
428  * nfs_async_rename - perform an asynchronous rename operation
429  * @old_dir: directory that currently holds the dentry to be renamed
430  * @new_dir: target directory for the rename
431  * @old_dentry: original dentry to be renamed
432  * @new_dentry: dentry to which the old_dentry should be renamed
433  *
434  * It's expected that valid references to the dentries and inodes are held
435  */
436 static struct rpc_task *
437 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
438                  struct dentry *old_dentry, struct dentry *new_dentry)
439 {
440         struct nfs_renamedata *data;
441         struct rpc_message msg = { };
442         struct rpc_task_setup task_setup_data = {
443                 .rpc_message = &msg,
444                 .callback_ops = &nfs_rename_ops,
445                 .workqueue = nfsiod_workqueue,
446                 .rpc_client = NFS_CLIENT(old_dir),
447                 .flags = RPC_TASK_ASYNC,
448         };
449
450         data = kzalloc(sizeof(*data), GFP_KERNEL);
451         if (data == NULL)
452                 return ERR_PTR(-ENOMEM);
453         task_setup_data.callback_data = data;
454
455         data->cred = rpc_lookup_cred();
456         if (IS_ERR(data->cred)) {
457                 struct rpc_task *task = ERR_CAST(data->cred);
458                 kfree(data);
459                 return task;
460         }
461
462         msg.rpc_argp = &data->args;
463         msg.rpc_resp = &data->res;
464         msg.rpc_cred = data->cred;
465
466         /* set up nfs_renamedata */
467         data->old_dir = old_dir;
468         ihold(old_dir);
469         data->new_dir = new_dir;
470         ihold(new_dir);
471         data->old_dentry = dget(old_dentry);
472         data->new_dentry = dget(new_dentry);
473         nfs_fattr_init(&data->old_fattr);
474         nfs_fattr_init(&data->new_fattr);
475
476         /* set up nfs_renameargs */
477         data->args.old_dir = NFS_FH(old_dir);
478         data->args.old_name = &old_dentry->d_name;
479         data->args.new_dir = NFS_FH(new_dir);
480         data->args.new_name = &new_dentry->d_name;
481
482         /* set up nfs_renameres */
483         data->res.old_fattr = &data->old_fattr;
484         data->res.new_fattr = &data->new_fattr;
485
486         nfs_sb_active(old_dir->i_sb);
487
488         NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dir);
489
490         return rpc_run_task(&task_setup_data);
491 }
492
493 /**
494  * nfs_sillyrename - Perform a silly-rename of a dentry
495  * @dir: inode of directory that contains dentry
496  * @dentry: dentry to be sillyrenamed
497  *
498  * NFSv2/3 is stateless and the server doesn't know when the client is
499  * holding a file open. To prevent application problems when a file is
500  * unlinked while it's still open, the client performs a "silly-rename".
501  * That is, it renames the file to a hidden file in the same directory,
502  * and only performs the unlink once the last reference to it is put.
503  *
504  * The final cleanup is done during dentry_iput.
505  *
506  * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
507  * could take responsibility for keeping open files referenced.  The server
508  * would also need to ensure that opened-but-deleted files were kept over
509  * reboots.  However, we may not assume a server does so.  (RFC 5661
510  * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
511  * use to advertise that it does this; some day we may take advantage of
512  * it.))
513  */
514 int
515 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
516 {
517         static unsigned int sillycounter;
518         const int      fileidsize  = sizeof(NFS_FILEID(dentry->d_inode))*2;
519         const int      countersize = sizeof(sillycounter)*2;
520         const int      slen        = sizeof(".nfs")+fileidsize+countersize-1;
521         char           silly[slen+1];
522         struct dentry *sdentry;
523         struct rpc_task *task;
524         int            error = -EIO;
525
526         dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n",
527                 dentry->d_parent->d_name.name, dentry->d_name.name,
528                 dentry->d_count);
529         nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
530
531         /*
532          * We don't allow a dentry to be silly-renamed twice.
533          */
534         error = -EBUSY;
535         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
536                 goto out;
537
538         sprintf(silly, ".nfs%*.*Lx",
539                 fileidsize, fileidsize,
540                 (unsigned long long)NFS_FILEID(dentry->d_inode));
541
542         /* Return delegation in anticipation of the rename */
543         nfs_inode_return_delegation(dentry->d_inode);
544
545         sdentry = NULL;
546         do {
547                 char *suffix = silly + slen - countersize;
548
549                 dput(sdentry);
550                 sillycounter++;
551                 sprintf(suffix, "%*.*x", countersize, countersize, sillycounter);
552
553                 dfprintk(VFS, "NFS: trying to rename %s to %s\n",
554                                 dentry->d_name.name, silly);
555
556                 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
557                 /*
558                  * N.B. Better to return EBUSY here ... it could be
559                  * dangerous to delete the file while it's in use.
560                  */
561                 if (IS_ERR(sdentry))
562                         goto out;
563         } while (sdentry->d_inode != NULL); /* need negative lookup */
564
565         /* queue unlink first. Can't do this from rpc_release as it
566          * has to allocate memory
567          */
568         error = nfs_async_unlink(dir, dentry);
569         if (error)
570                 goto out_dput;
571
572         /* populate unlinkdata with the right dname */
573         error = nfs_copy_dname(sdentry,
574                                 (struct nfs_unlinkdata *)dentry->d_fsdata);
575         if (error) {
576                 nfs_cancel_async_unlink(dentry);
577                 goto out_dput;
578         }
579
580         /* run the rename task, undo unlink if it fails */
581         task = nfs_async_rename(dir, dir, dentry, sdentry);
582         if (IS_ERR(task)) {
583                 error = -EBUSY;
584                 nfs_cancel_async_unlink(dentry);
585                 goto out_dput;
586         }
587
588         /* wait for the RPC task to complete, unless a SIGKILL intervenes */
589         error = rpc_wait_for_completion_task(task);
590         if (error == 0)
591                 error = task->tk_status;
592         rpc_put_task(task);
593 out_dput:
594         dput(sdentry);
595 out:
596         return error;
597 }