File: /usr/src/linux/fs/nfs/dir.c
1 /*
2 * linux/fs/nfs/dir.c
3 *
4 * Copyright (C) 1992 Rick Sladkey
5 *
6 * nfs directory handling functions
7 *
8 * 10 Apr 1996 Added silly rename for unlink --okir
9 * 28 Sep 1996 Improved directory cache --okir
10 * 23 Aug 1997 Claus Heine claus@momo.math.rwth-aachen.de
11 * Re-implemented silly rename for unlink, newly implemented
12 * silly rename for nfs_rename() following the suggestions
13 * of Olaf Kirch (okir) found in this file.
14 * Following Linus comments on my original hack, this version
15 * depends only on the dcache stuff and doesn't touch the inode
16 * layer (iput() and friends).
17 * 6 Jun 1999 Cache readdir lookups in the page cache. -DaveM
18 */
19
20 #include <linux/sched.h>
21 #include <linux/errno.h>
22 #include <linux/stat.h>
23 #include <linux/fcntl.h>
24 #include <linux/string.h>
25 #include <linux/kernel.h>
26 #include <linux/slab.h>
27 #include <linux/mm.h>
28 #include <linux/sunrpc/clnt.h>
29 #include <linux/nfs_fs.h>
30 #include <linux/nfs_mount.h>
31 #include <linux/pagemap.h>
32 #include <linux/smp_lock.h>
33
34 #define NFS_PARANOIA 1
35 /* #define NFS_DEBUG_VERBOSE 1 */
36
37 static int nfs_readdir(struct file *, void *, filldir_t);
38 static struct dentry *nfs_lookup(struct inode *, struct dentry *);
39 static int nfs_create(struct inode *, struct dentry *, int);
40 static int nfs_mkdir(struct inode *, struct dentry *, int);
41 static int nfs_rmdir(struct inode *, struct dentry *);
42 static int nfs_unlink(struct inode *, struct dentry *);
43 static int nfs_symlink(struct inode *, struct dentry *, const char *);
44 static int nfs_link(struct dentry *, struct inode *, struct dentry *);
45 static int nfs_mknod(struct inode *, struct dentry *, int, int);
46 static int nfs_rename(struct inode *, struct dentry *,
47 struct inode *, struct dentry *);
48
49 struct file_operations nfs_dir_operations = {
50 read: generic_read_dir,
51 readdir: nfs_readdir,
52 open: nfs_open,
53 release: nfs_release,
54 };
55
56 struct inode_operations nfs_dir_inode_operations = {
57 create: nfs_create,
58 lookup: nfs_lookup,
59 link: nfs_link,
60 unlink: nfs_unlink,
61 symlink: nfs_symlink,
62 mkdir: nfs_mkdir,
63 rmdir: nfs_rmdir,
64 mknod: nfs_mknod,
65 rename: nfs_rename,
66 permission: nfs_permission,
67 revalidate: nfs_revalidate,
68 setattr: nfs_notify_change,
69 };
70
71 typedef u32 * (*decode_dirent_t)(u32 *, struct nfs_entry *, int);
72 typedef struct {
73 struct file *file;
74 struct page *page;
75 unsigned long page_index;
76 u32 *ptr;
77 u64 target;
78 struct nfs_entry *entry;
79 decode_dirent_t decode;
80 int plus;
81 int error;
82 } nfs_readdir_descriptor_t;
83
84 /* Now we cache directories properly, by stuffing the dirent
85 * data directly in the page cache.
86 *
87 * Inode invalidation due to refresh etc. takes care of
88 * _everything_, no sloppy entry flushing logic, no extraneous
89 * copying, network direct to page cache, the way it was meant
90 * to be.
91 *
92 * NOTE: Dirent information verification is done always by the
93 * page-in of the RPC reply, nowhere else, this simplies
94 * things substantially.
95 */
96 static
97 int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page *page)
98 {
99 struct file *file = desc->file;
100 struct inode *inode = file->f_dentry->d_inode;
101 struct rpc_cred *cred = nfs_file_cred(file);
102 void *buffer = kmap(page);
103 int error;
104
105 dfprintk(VFS, "NFS: nfs_readdir_filler() reading cookie %Lu into page %lu.\n", (long long)desc->entry->cookie, page->index);
106
107 again:
108 error = NFS_PROTO(inode)->readdir(inode, cred, desc->entry->cookie, buffer,
109 NFS_SERVER(inode)->dtsize, desc->plus);
110 /* We requested READDIRPLUS, but the server doesn't grok it */
111 if (desc->plus && error == -ENOTSUPP) {
112 NFS_FLAGS(inode) &= ~NFS_INO_ADVISE_RDPLUS;
113 desc->plus = 0;
114 goto again;
115 }
116 if (error < 0)
117 goto error;
118 SetPageUptodate(page);
119 kunmap(page);
120 /* Ensure consistent page alignment of the data.
121 * Note: assumes we have exclusive access to this mapping either
122 * throught inode->i_sem or some other mechanism.
123 */
124 if (page->index == 0)
125 invalidate_inode_pages(inode);
126 UnlockPage(page);
127 return 0;
128 error:
129 SetPageError(page);
130 kunmap(page);
131 UnlockPage(page);
132 invalidate_inode_pages(inode);
133 desc->error = error;
134 return -EIO;
135 }
136
137 static inline
138 int dir_decode(nfs_readdir_descriptor_t *desc)
139 {
140 u32 *p = desc->ptr;
141 p = desc->decode(p, desc->entry, desc->plus);
142 if (IS_ERR(p))
143 return PTR_ERR(p);
144 desc->ptr = p;
145 return 0;
146 }
147
148 static inline
149 void dir_page_release(nfs_readdir_descriptor_t *desc)
150 {
151 kunmap(desc->page);
152 page_cache_release(desc->page);
153 desc->page = NULL;
154 desc->ptr = NULL;
155 }
156
157 /*
158 * Given a pointer to a buffer that has already been filled by a call
159 * to readdir, find the next entry.
160 *
161 * If the end of the buffer has been reached, return -EAGAIN, if not,
162 * return the offset within the buffer of the next entry to be
163 * read.
164 */
165 static inline
166 int find_dirent(nfs_readdir_descriptor_t *desc, struct page *page)
167 {
168 struct nfs_entry *entry = desc->entry;
169 int loop_count = 0,
170 status;
171
172 while((status = dir_decode(desc)) == 0) {
173 dfprintk(VFS, "NFS: found cookie %Lu\n", (long long)entry->cookie);
174 if (entry->prev_cookie == desc->target)
175 break;
176 if (loop_count++ > 200) {
177 loop_count = 0;
178 schedule();
179 }
180 }
181 dfprintk(VFS, "NFS: find_dirent() returns %d\n", status);
182 return status;
183 }
184
185 /*
186 * Find the given page, and call find_dirent() in order to try to
187 * return the next entry.
188 */
189 static inline
190 int find_dirent_page(nfs_readdir_descriptor_t *desc)
191 {
192 struct inode *inode = desc->file->f_dentry->d_inode;
193 struct page *page;
194 int status;
195
196 dfprintk(VFS, "NFS: find_dirent_page() searching directory page %ld\n", desc->page_index);
197
198 desc->plus = NFS_USE_READDIRPLUS(inode);
199 page = read_cache_page(&inode->i_data, desc->page_index,
200 (filler_t *)nfs_readdir_filler, desc);
201 if (IS_ERR(page)) {
202 status = PTR_ERR(page);
203 goto out;
204 }
205 if (!Page_Uptodate(page))
206 goto read_error;
207
208 /* NOTE: Someone else may have changed the READDIRPLUS flag */
209 desc->page = page;
210 desc->ptr = kmap(page);
211 status = find_dirent(desc, page);
212 if (status < 0)
213 dir_page_release(desc);
214 out:
215 dfprintk(VFS, "NFS: find_dirent_page() returns %d\n", status);
216 return status;
217 read_error:
218 page_cache_release(page);
219 return -EIO;
220 }
221
222 /*
223 * Recurse through the page cache pages, and return a
224 * filled nfs_entry structure of the next directory entry if possible.
225 *
226 * The target for the search is 'desc->target'.
227 */
228 static inline
229 int readdir_search_pagecache(nfs_readdir_descriptor_t *desc)
230 {
231 int loop_count = 0;
232 int res;
233
234 dfprintk(VFS, "NFS: readdir_search_pagecache() searching for cookie %Lu\n", (long long)desc->target);
235 for (;;) {
236 res = find_dirent_page(desc);
237 if (res != -EAGAIN)
238 break;
239 /* Align to beginning of next page */
240 desc->page_index ++;
241 if (loop_count++ > 200) {
242 loop_count = 0;
243 schedule();
244 }
245 }
246 dfprintk(VFS, "NFS: readdir_search_pagecache() returned %d\n", res);
247 return res;
248 }
249
250 /*
251 * Once we've found the start of the dirent within a page: fill 'er up...
252 */
253 static
254 int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent,
255 filldir_t filldir)
256 {
257 struct file *file = desc->file;
258 struct nfs_entry *entry = desc->entry;
259 unsigned long fileid;
260 int loop_count = 0,
261 res;
262
263 dfprintk(VFS, "NFS: nfs_do_filldir() filling starting @ cookie %Lu\n", (long long)desc->target);
264
265 for(;;) {
266 /* Note: entry->prev_cookie contains the cookie for
267 * retrieving the current dirent on the server */
268 fileid = nfs_fileid_to_ino_t(entry->ino);
269 res = filldir(dirent, entry->name, entry->len,
270 entry->prev_cookie, fileid, DT_UNKNOWN);
271 if (res < 0)
272 break;
273 file->f_pos = desc->target = entry->cookie;
274 if (dir_decode(desc) != 0) {
275 desc->page_index ++;
276 break;
277 }
278 if (loop_count++ > 200) {
279 loop_count = 0;
280 schedule();
281 }
282 }
283 dir_page_release(desc);
284
285 dfprintk(VFS, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n", (long long)desc->target, res);
286 return res;
287 }
288
289 /*
290 * If we cannot find a cookie in our cache, we suspect that this is
291 * because it points to a deleted file, so we ask the server to return
292 * whatever it thinks is the next entry. We then feed this to filldir.
293 * If all goes well, we should then be able to find our way round the
294 * cache on the next call to readdir_search_pagecache();
295 *
296 * NOTE: we cannot add the anonymous page to the pagecache because
297 * the data it contains might not be page aligned. Besides,
298 * we should already have a complete representation of the
299 * directory in the page cache by the time we get here.
300 */
301 static inline
302 int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent,
303 filldir_t filldir)
304 {
305 struct file *file = desc->file;
306 struct inode *inode = file->f_dentry->d_inode;
307 struct rpc_cred *cred = nfs_file_cred(file);
308 struct page *page = NULL;
309 int status;
310
311 dfprintk(VFS, "NFS: uncached_readdir() searching for cookie %Lu\n", (long long)desc->target);
312
313 page = alloc_page(GFP_HIGHUSER);
314 if (!page) {
315 status = -ENOMEM;
316 goto out;
317 }
318 desc->page = page;
319 desc->ptr = kmap(page);
320 desc->error = NFS_PROTO(inode)->readdir(inode, cred, desc->target,
321 desc->ptr,
322 NFS_SERVER(inode)->dtsize,
323 desc->plus);
324 if (desc->error >= 0) {
325 if ((status = dir_decode(desc)) == 0)
326 desc->entry->prev_cookie = desc->target;
327 } else
328 status = -EIO;
329 if (status < 0)
330 goto out_release;
331
332 status = nfs_do_filldir(desc, dirent, filldir);
333
334 /* Reset read descriptor so it searches the page cache from
335 * the start upon the next call to readdir_search_pagecache() */
336 desc->page_index = 0;
337 memset(desc->entry, 0, sizeof(*desc->entry));
338 out:
339 dfprintk(VFS, "NFS: uncached_readdir() returns %d\n", status);
340 return status;
341 out_release:
342 dir_page_release(desc);
343 goto out;
344 }
345
346 /* The file offset position is now represented as a true offset into the
347 * page cache as is the case in most of the other filesystems.
348 */
349 static int nfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
350 {
351 struct dentry *dentry = filp->f_dentry;
352 struct inode *inode = dentry->d_inode;
353 nfs_readdir_descriptor_t my_desc,
354 *desc = &my_desc;
355 struct nfs_entry my_entry;
356 long res;
357
358 res = nfs_revalidate(dentry);
359 if (res < 0)
360 return res;
361
362 /*
363 * filp->f_pos points to the file offset in the page cache.
364 * but if the cache has meanwhile been zapped, we need to
365 * read from the last dirent to revalidate f_pos
366 * itself.
367 */
368 memset(desc, 0, sizeof(*desc));
369 memset(&my_entry, 0, sizeof(my_entry));
370
371 desc->file = filp;
372 desc->target = filp->f_pos;
373 desc->entry = &my_entry;
374 desc->decode = NFS_PROTO(inode)->decode_dirent;
375
376 while(!desc->entry->eof) {
377 res = readdir_search_pagecache(desc);
378 if (res == -EBADCOOKIE) {
379 /* This means either end of directory */
380 if (desc->entry->cookie != desc->target) {
381 /* Or that the server has 'lost' a cookie */
382 res = uncached_readdir(desc, dirent, filldir);
383 if (res >= 0)
384 continue;
385 }
386 res = 0;
387 break;
388 } else if (res < 0)
389 break;
390
391 res = nfs_do_filldir(desc, dirent, filldir);
392 if (res < 0) {
393 res = 0;
394 break;
395 }
396 }
397 if (desc->error < 0)
398 return desc->error;
399 if (res < 0)
400 return res;
401 return 0;
402 }
403
404 /*
405 * Whenever an NFS operation succeeds, we know that the dentry
406 * is valid, so we update the revalidation timestamp.
407 */
408 static inline void nfs_renew_times(struct dentry * dentry)
409 {
410 dentry->d_time = jiffies;
411 }
412
413 static inline int nfs_dentry_force_reval(struct dentry *dentry, int flags)
414 {
415 struct inode *inode = dentry->d_inode;
416 unsigned long timeout = NFS_ATTRTIMEO(inode);
417
418 /*
419 * If it's the last lookup in a series, we use a stricter
420 * cache consistency check by looking at the parent mtime.
421 *
422 * If it's been modified in the last hour, be really strict.
423 * (This still means that we can avoid doing unnecessary
424 * work on directories like /usr/share/bin etc which basically
425 * never change).
426 */
427 if (!(flags & LOOKUP_CONTINUE)) {
428 long diff = CURRENT_TIME - dentry->d_parent->d_inode->i_mtime;
429
430 if (diff < 15*60)
431 timeout = 0;
432 }
433
434 return time_after(jiffies,dentry->d_time + timeout);
435 }
436
437 /*
438 * We judge how long we want to trust negative
439 * dentries by looking at the parent inode mtime.
440 *
441 * If mtime is close to present time, we revalidate
442 * more often.
443 */
444 #define NFS_REVALIDATE_NEGATIVE (1 * HZ)
445 static inline int nfs_neg_need_reval(struct dentry *dentry)
446 {
447 struct inode *dir = dentry->d_parent->d_inode;
448 unsigned long timeout = NFS_ATTRTIMEO(dir);
449 long diff = CURRENT_TIME - dir->i_mtime;
450
451 if (diff < 5*60 && timeout > NFS_REVALIDATE_NEGATIVE)
452 timeout = NFS_REVALIDATE_NEGATIVE;
453
454 return time_after(jiffies, dentry->d_time + timeout);
455 }
456
457 /*
458 * This is called every time the dcache has a lookup hit,
459 * and we should check whether we can really trust that
460 * lookup.
461 *
462 * NOTE! The hit can be a negative hit too, don't assume
463 * we have an inode!
464 *
465 * If the dentry is older than the revalidation interval,
466 * we do a new lookup and verify that the dentry is still
467 * correct.
468 */
469 static int nfs_lookup_revalidate(struct dentry * dentry, int flags)
470 {
471 struct inode *dir;
472 struct inode *inode;
473 int error;
474 struct nfs_fh fhandle;
475 struct nfs_fattr fattr;
476
477 lock_kernel();
478 dir = dentry->d_parent->d_inode;
479 inode = dentry->d_inode;
480 /*
481 * If we don't have an inode, let's look at the parent
482 * directory mtime to get a hint about how often we
483 * should validate things..
484 */
485 if (!inode) {
486 if (nfs_neg_need_reval(dentry))
487 goto out_bad;
488 goto out_valid;
489 }
490
491 if (is_bad_inode(inode)) {
492 dfprintk(VFS, "nfs_lookup_validate: %s/%s has dud inode\n",
493 dentry->d_parent->d_name.name, dentry->d_name.name);
494 goto out_bad;
495 }
496
497 if (!nfs_dentry_force_reval(dentry, flags))
498 goto out_valid;
499
500 if (IS_ROOT(dentry)) {
501 __nfs_revalidate_inode(NFS_SERVER(inode), inode);
502 goto out_valid_renew;
503 }
504
505 /*
506 * Do a new lookup and check the dentry attributes.
507 */
508 error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, &fhandle, &fattr);
509 if (error)
510 goto out_bad;
511
512 /* Inode number matches? */
513 if (!(fattr.valid & NFS_ATTR_FATTR) ||
514 NFS_FSID(inode) != fattr.fsid ||
515 NFS_FILEID(inode) != fattr.fileid)
516 goto out_bad;
517
518 /* Ok, remember that we successfully checked it.. */
519 nfs_refresh_inode(inode, &fattr);
520
521 if (nfs_inode_is_stale(inode, &fhandle, &fattr))
522 goto out_bad;
523
524 out_valid_renew:
525 nfs_renew_times(dentry);
526 out_valid:
527 unlock_kernel();
528 return 1;
529 out_bad:
530 shrink_dcache_parent(dentry);
531 /* If we have submounts, don't unhash ! */
532 if (have_submounts(dentry))
533 goto out_valid;
534 d_drop(dentry);
535 /* Purge readdir caches. */
536 nfs_zap_caches(dir);
537 if (inode && S_ISDIR(inode->i_mode))
538 nfs_zap_caches(inode);
539 unlock_kernel();
540 return 0;
541 }
542
543 /*
544 * This is called from dput() when d_count is going to 0.
545 */
546 static int nfs_dentry_delete(struct dentry *dentry)
547 {
548 dfprintk(VFS, "NFS: dentry_delete(%s/%s, %x)\n",
549 dentry->d_parent->d_name.name, dentry->d_name.name,
550 dentry->d_flags);
551
552 if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
553 /* Unhash it, so that ->d_iput() would be called */
554 return 1;
555 }
556 return 0;
557
558 }
559
560 /*
561 * Called when the dentry loses inode.
562 * We use it to clean up silly-renamed files.
563 */
564 static void nfs_dentry_iput(struct dentry *dentry, struct inode *inode)
565 {
566 if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
567 lock_kernel();
568 nfs_complete_unlink(dentry);
569 unlock_kernel();
570 }
571 iput(inode);
572 }
573
574 struct dentry_operations nfs_dentry_operations = {
575 d_revalidate: nfs_lookup_revalidate,
576 d_delete: nfs_dentry_delete,
577 d_iput: nfs_dentry_iput,
578 };
579
580 static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry)
581 {
582 struct inode *inode;
583 int error;
584 struct nfs_fh fhandle;
585 struct nfs_fattr fattr;
586
587 dfprintk(VFS, "NFS: lookup(%s/%s)\n",
588 dentry->d_parent->d_name.name, dentry->d_name.name);
589
590 error = -ENAMETOOLONG;
591 if (dentry->d_name.len > NFS_SERVER(dir)->namelen)
592 goto out;
593
594 error = -ENOMEM;
595 dentry->d_op = &nfs_dentry_operations;
596
597 error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, &fhandle, &fattr);
598 inode = NULL;
599 if (error == -ENOENT)
600 goto no_entry;
601 if (!error) {
602 error = -EACCES;
603 inode = nfs_fhget(dentry, &fhandle, &fattr);
604 if (inode) {
605 no_entry:
606 d_add(dentry, inode);
607 nfs_renew_times(dentry);
608 error = 0;
609 }
610 }
611 out:
612 return ERR_PTR(error);
613 }
614
615 /*
616 * Code common to create, mkdir, and mknod.
617 */
618 static int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
619 struct nfs_fattr *fattr)
620 {
621 struct inode *inode;
622 int error = -EACCES;
623
624 inode = nfs_fhget(dentry, fhandle, fattr);
625 if (inode) {
626 d_instantiate(dentry, inode);
627 nfs_renew_times(dentry);
628 error = 0;
629 }
630 return error;
631 }
632
633 /*
634 * Following a failed create operation, we drop the dentry rather
635 * than retain a negative dentry. This avoids a problem in the event
636 * that the operation succeeded on the server, but an error in the
637 * reply path made it appear to have failed.
638 */
639 static int nfs_create(struct inode *dir, struct dentry *dentry, int mode)
640 {
641 struct iattr attr;
642 struct nfs_fattr fattr;
643 struct nfs_fh fhandle;
644 int error;
645
646 dfprintk(VFS, "NFS: create(%x/%ld, %s\n",
647 dir->i_dev, dir->i_ino, dentry->d_name.name);
648
649 attr.ia_mode = mode;
650 attr.ia_valid = ATTR_MODE;
651
652 /*
653 * The 0 argument passed into the create function should one day
654 * contain the O_EXCL flag if requested. This allows NFSv3 to
655 * select the appropriate create strategy. Currently open_namei
656 * does not pass the create flags.
657 */
658 nfs_zap_caches(dir);
659 error = NFS_PROTO(dir)->create(dir, &dentry->d_name,
660 &attr, 0, &fhandle, &fattr);
661 if (!error && fhandle.size != 0)
662 error = nfs_instantiate(dentry, &fhandle, &fattr);
663 if (error || fhandle.size == 0)
664 d_drop(dentry);
665 return error;
666 }
667
668 /*
669 * See comments for nfs_proc_create regarding failed operations.
670 */
671 static int nfs_mknod(struct inode *dir, struct dentry *dentry, int mode, int rdev)
672 {
673 struct iattr attr;
674 struct nfs_fattr fattr;
675 struct nfs_fh fhandle;
676 int error;
677
678 dfprintk(VFS, "NFS: mknod(%x/%ld, %s\n",
679 dir->i_dev, dir->i_ino, dentry->d_name.name);
680
681 attr.ia_mode = mode;
682 attr.ia_valid = ATTR_MODE;
683
684 nfs_zap_caches(dir);
685 error = NFS_PROTO(dir)->mknod(dir, &dentry->d_name, &attr, rdev,
686 &fhandle, &fattr);
687 if (!error && fhandle.size != 0)
688 error = nfs_instantiate(dentry, &fhandle, &fattr);
689 if (error || fhandle.size == 0)
690 d_drop(dentry);
691 return error;
692 }
693
694 /*
695 * See comments for nfs_proc_create regarding failed operations.
696 */
697 static int nfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
698 {
699 struct iattr attr;
700 struct nfs_fattr fattr;
701 struct nfs_fh fhandle;
702 int error;
703
704 dfprintk(VFS, "NFS: mkdir(%x/%ld, %s\n",
705 dir->i_dev, dir->i_ino, dentry->d_name.name);
706
707 attr.ia_valid = ATTR_MODE;
708 attr.ia_mode = mode | S_IFDIR;
709
710 #if 0
711 /*
712 * Always drop the dentry, we can't always depend on
713 * the fattr returned by the server (AIX seems to be
714 * broken). We're better off doing another lookup than
715 * depending on potentially bogus information.
716 */
717 d_drop(dentry);
718 #endif
719 nfs_zap_caches(dir);
720 error = NFS_PROTO(dir)->mkdir(dir, &dentry->d_name, &attr, &fhandle,
721 &fattr);
722 if (!error && fhandle.size != 0)
723 error = nfs_instantiate(dentry, &fhandle, &fattr);
724 if (error || fhandle.size == 0)
725 d_drop(dentry);
726 return error;
727 }
728
729 static int nfs_rmdir(struct inode *dir, struct dentry *dentry)
730 {
731 int error;
732
733 dfprintk(VFS, "NFS: rmdir(%x/%ld, %s\n",
734 dir->i_dev, dir->i_ino, dentry->d_name.name);
735
736 nfs_zap_caches(dir);
737 error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
738 if (!error)
739 dentry->d_inode->i_nlink = 0;
740
741 return error;
742 }
743
744 static int nfs_sillyrename(struct inode *dir, struct dentry *dentry)
745 {
746 static unsigned int sillycounter;
747 const int i_inosize = sizeof(dir->i_ino)*2;
748 const int countersize = sizeof(sillycounter)*2;
749 const int slen = strlen(".nfs") + i_inosize + countersize;
750 char silly[slen+1];
751 struct qstr qsilly;
752 struct dentry *sdentry;
753 int error = -EIO;
754
755 dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n",
756 dentry->d_parent->d_name.name, dentry->d_name.name,
757 atomic_read(&dentry->d_count));
758
759 if (atomic_read(&dentry->d_count) == 1)
760 goto out; /* No need to silly rename. */
761
762
763 #ifdef NFS_PARANOIA
764 if (!dentry->d_inode)
765 printk("NFS: silly-renaming %s/%s, negative dentry??\n",
766 dentry->d_parent->d_name.name, dentry->d_name.name);
767 #endif
768 /*
769 * We don't allow a dentry to be silly-renamed twice.
770 */
771 error = -EBUSY;
772 if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
773 goto out;
774
775 sprintf(silly, ".nfs%*.*lx",
776 i_inosize, i_inosize, dentry->d_inode->i_ino);
777
778 sdentry = NULL;
779 do {
780 char *suffix = silly + slen - countersize;
781
782 dput(sdentry);
783 sillycounter++;
784 sprintf(suffix, "%*.*x", countersize, countersize, sillycounter);
785
786 dfprintk(VFS, "trying to rename %s to %s\n",
787 dentry->d_name.name, silly);
788
789 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
790 /*
791 * N.B. Better to return EBUSY here ... it could be
792 * dangerous to delete the file while it's in use.
793 */
794 if (IS_ERR(sdentry))
795 goto out;
796 } while(sdentry->d_inode != NULL); /* need negative lookup */
797
798 nfs_zap_caches(dir);
799 qsilly.name = silly;
800 qsilly.len = strlen(silly);
801 error = NFS_PROTO(dir)->rename(dir, &dentry->d_name, dir, &qsilly);
802 if (!error) {
803 nfs_renew_times(dentry);
804 d_move(dentry, sdentry);
805 error = nfs_async_unlink(dentry);
806 /* If we return 0 we don't unlink */
807 }
808 dput(sdentry);
809 out:
810 return error;
811 }
812
813 /*
814 * Remove a file after making sure there are no pending writes,
815 * and after checking that the file has only one user.
816 *
817 * We invalidate the attribute cache and free the inode prior to the operation
818 * to avoid possible races if the server reuses the inode.
819 */
820 static int nfs_safe_remove(struct dentry *dentry)
821 {
822 struct inode *dir = dentry->d_parent->d_inode;
823 struct inode *inode = dentry->d_inode;
824 int error = -EBUSY, rehash = 0;
825
826 dfprintk(VFS, "NFS: safe_remove(%s/%s)\n",
827 dentry->d_parent->d_name.name, dentry->d_name.name);
828
829 /*
830 * Unhash the dentry while we remove the file ...
831 */
832 if (!d_unhashed(dentry)) {
833 d_drop(dentry);
834 rehash = 1;
835 }
836 if (atomic_read(&dentry->d_count) > 1) {
837 #ifdef NFS_PARANOIA
838 printk("nfs_safe_remove: %s/%s busy, d_count=%d\n",
839 dentry->d_parent->d_name.name, dentry->d_name.name,
840 atomic_read(&dentry->d_count));
841 #endif
842 goto out;
843 }
844
845 /* If the dentry was sillyrenamed, we simply call d_delete() */
846 if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
847 error = 0;
848 goto out_delete;
849 }
850
851 nfs_zap_caches(dir);
852 if (inode)
853 NFS_CACHEINV(inode);
854 error = NFS_PROTO(dir)->remove(dir, &dentry->d_name);
855 if (error < 0)
856 goto out;
857 if (inode)
858 inode->i_nlink--;
859
860 out_delete:
861 /*
862 * Free the inode
863 */
864 d_delete(dentry);
865 out:
866 if (rehash)
867 d_rehash(dentry);
868 return error;
869 }
870
871 /* We do silly rename. In case sillyrename() returns -EBUSY, the inode
872 * belongs to an active ".nfs..." file and we return -EBUSY.
873 *
874 * If sillyrename() returns 0, we do nothing, otherwise we unlink.
875 */
876 static int nfs_unlink(struct inode *dir, struct dentry *dentry)
877 {
878 int error;
879
880 dfprintk(VFS, "NFS: unlink(%x/%ld, %s)\n",
881 dir->i_dev, dir->i_ino, dentry->d_name.name);
882
883 error = nfs_sillyrename(dir, dentry);
884 if (error && error != -EBUSY) {
885 error = nfs_safe_remove(dentry);
886 if (!error) {
887 nfs_renew_times(dentry);
888 }
889 }
890 return error;
891 }
892
893 static int
894 nfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
895 {
896 struct iattr attr;
897 struct nfs_fattr sym_attr;
898 struct nfs_fh sym_fh;
899 struct qstr qsymname;
900 unsigned int maxlen;
901 int error;
902
903 dfprintk(VFS, "NFS: symlink(%x/%ld, %s, %s)\n",
904 dir->i_dev, dir->i_ino, dentry->d_name.name, symname);
905
906 error = -ENAMETOOLONG;
907 maxlen = (NFS_PROTO(dir)->version==2) ? NFS2_MAXPATHLEN : NFS3_MAXPATHLEN;
908 if (strlen(symname) > maxlen)
909 goto out;
910
911 #ifdef NFS_PARANOIA
912 if (dentry->d_inode)
913 printk("nfs_proc_symlink: %s/%s not negative!\n",
914 dentry->d_parent->d_name.name, dentry->d_name.name);
915 #endif
916 /*
917 * Fill in the sattr for the call.
918 * Note: SunOS 4.1.2 crashes if the mode isn't initialized!
919 */
920 attr.ia_valid = ATTR_MODE;
921 attr.ia_mode = S_IFLNK | S_IRWXUGO;
922
923 qsymname.name = symname;
924 qsymname.len = strlen(symname);
925
926 nfs_zap_caches(dir);
927 error = NFS_PROTO(dir)->symlink(dir, &dentry->d_name, &qsymname,
928 &attr, &sym_fh, &sym_attr);
929 if (!error && sym_fh.size != 0 && (sym_attr.valid & NFS_ATTR_FATTR)) {
930 error = nfs_instantiate(dentry, &sym_fh, &sym_attr);
931 } else {
932 if (error == -EEXIST)
933 printk("nfs_proc_symlink: %s/%s already exists??\n",
934 dentry->d_parent->d_name.name, dentry->d_name.name);
935 d_drop(dentry);
936 }
937
938 out:
939 return error;
940 }
941
942 static int
943 nfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
944 {
945 struct inode *inode = old_dentry->d_inode;
946 int error;
947
948 dfprintk(VFS, "NFS: link(%s/%s -> %s/%s)\n",
949 old_dentry->d_parent->d_name.name, old_dentry->d_name.name,
950 dentry->d_parent->d_name.name, dentry->d_name.name);
951
952 /*
953 * Drop the dentry in advance to force a new lookup.
954 * Since nfs_proc_link doesn't return a file handle,
955 * we can't use the existing dentry.
956 */
957 d_drop(dentry);
958 nfs_zap_caches(dir);
959 NFS_CACHEINV(inode);
960 error = NFS_PROTO(dir)->link(inode, dir, &dentry->d_name);
961 return error;
962 }
963
964 /*
965 * RENAME
966 * FIXME: Some nfsds, like the Linux user space nfsd, may generate a
967 * different file handle for the same inode after a rename (e.g. when
968 * moving to a different directory). A fail-safe method to do so would
969 * be to look up old_dir/old_name, create a link to new_dir/new_name and
970 * rename the old file using the sillyrename stuff. This way, the original
971 * file in old_dir will go away when the last process iput()s the inode.
972 *
973 * FIXED.
974 *
975 * It actually works quite well. One needs to have the possibility for
976 * at least one ".nfs..." file in each directory the file ever gets
977 * moved or linked to which happens automagically with the new
978 * implementation that only depends on the dcache stuff instead of
979 * using the inode layer
980 *
981 * Unfortunately, things are a little more complicated than indicated
982 * above. For a cross-directory move, we want to make sure we can get
983 * rid of the old inode after the operation. This means there must be
984 * no pending writes (if it's a file), and the use count must be 1.
985 * If these conditions are met, we can drop the dentries before doing
986 * the rename.
987 */
988 static int nfs_rename(struct inode *old_dir, struct dentry *old_dentry,
989 struct inode *new_dir, struct dentry *new_dentry)
990 {
991 struct inode *old_inode = old_dentry->d_inode;
992 struct inode *new_inode = new_dentry->d_inode;
993 struct dentry *dentry = NULL, *rehash = NULL;
994 int error = -EBUSY;
995
996 /*
997 * To prevent any new references to the target during the rename,
998 * we unhash the dentry and free the inode in advance.
999 */
1000 if (!d_unhashed(new_dentry)) {
1001 d_drop(new_dentry);
1002 rehash = new_dentry;
1003 }
1004
1005 dfprintk(VFS, "NFS: rename(%s/%s -> %s/%s, ct=%d)\n",
1006 old_dentry->d_parent->d_name.name, old_dentry->d_name.name,
1007 new_dentry->d_parent->d_name.name, new_dentry->d_name.name,
1008 atomic_read(&new_dentry->d_count));
1009
1010 /*
1011 * First check whether the target is busy ... we can't
1012 * safely do _any_ rename if the target is in use.
1013 *
1014 * For files, make a copy of the dentry and then do a
1015 * silly-rename. If the silly-rename succeeds, the
1016 * copied dentry is hashed and becomes the new target.
1017 */
1018 if (!new_inode)
1019 goto go_ahead;
1020 if (S_ISDIR(new_inode->i_mode))
1021 goto out;
1022 else if (atomic_read(&new_dentry->d_count) > 1) {
1023 int err;
1024 /* copy the target dentry's name */
1025 dentry = d_alloc(new_dentry->d_parent,
1026 &new_dentry->d_name);
1027 if (!dentry)
1028 goto out;
1029
1030 /* silly-rename the existing target ... */
1031 err = nfs_sillyrename(new_dir, new_dentry);
1032 if (!err) {
1033 new_dentry = rehash = dentry;
1034 new_inode = NULL;
1035 /* instantiate the replacement target */
1036 d_instantiate(new_dentry, NULL);
1037 }
1038
1039 /* dentry still busy? */
1040 if (atomic_read(&new_dentry->d_count) > 1) {
1041 #ifdef NFS_PARANOIA
1042 printk("nfs_rename: target %s/%s busy, d_count=%d\n",
1043 new_dentry->d_parent->d_name.name,
1044 new_dentry->d_name.name,
1045 atomic_read(&new_dentry->d_count));
1046 #endif
1047 goto out;
1048 }
1049 }
1050
1051 go_ahead:
1052 /*
1053 * ... prune child dentries and writebacks if needed.
1054 */
1055 if (atomic_read(&old_dentry->d_count) > 1) {
1056 nfs_wb_all(old_inode);
1057 shrink_dcache_parent(old_dentry);
1058 }
1059
1060 if (new_inode)
1061 d_delete(new_dentry);
1062
1063 nfs_zap_caches(new_dir);
1064 nfs_zap_caches(old_dir);
1065 error = NFS_PROTO(old_dir)->rename(old_dir, &old_dentry->d_name,
1066 new_dir, &new_dentry->d_name);
1067 out:
1068 if (rehash)
1069 d_rehash(rehash);
1070 if (!error && !S_ISDIR(old_inode->i_mode))
1071 d_move(old_dentry, new_dentry);
1072
1073 /* new dentry created? */
1074 if (dentry)
1075 dput(dentry);
1076 return error;
1077 }
1078
1079 int
1080 nfs_permission(struct inode *inode, int mask)
1081 {
1082 int error = vfs_permission(inode, mask);
1083
1084 if (!NFS_PROTO(inode)->access)
1085 goto out;
1086
1087 if (error == -EROFS)
1088 goto out;
1089
1090 /*
1091 * Trust UNIX mode bits except:
1092 *
1093 * 1) When override capabilities may have been invoked
1094 * 2) When root squashing may be involved
1095 * 3) When ACLs may overturn a negative answer */
1096 if (!capable(CAP_DAC_OVERRIDE) && !capable(CAP_DAC_READ_SEARCH)
1097 && (current->fsuid != 0) && (current->fsgid != 0)
1098 && error != -EACCES)
1099 goto out;
1100
1101 error = NFS_PROTO(inode)->access(inode, mask, 0);
1102
1103 if (error == -EACCES && NFS_CLIENT(inode)->cl_droppriv &&
1104 current->uid != 0 && current->gid != 0 &&
1105 (current->fsuid != current->uid || current->fsgid != current->gid))
1106 error = NFS_PROTO(inode)->access(inode, mask, 1);
1107
1108 out:
1109 return error;
1110 }
1111
1112 /*
1113 * Local variables:
1114 * version-control: t
1115 * kept-new-versions: 5
1116 * End:
1117 */
1118