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TOMOYO Linux Cross Reference
Linux/fs/nfs/unlink.c

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

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