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Linux/fs/nfs/dir.c

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  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/module.h>
 21 #include <linux/time.h>
 22 #include <linux/errno.h>
 23 #include <linux/stat.h>
 24 #include <linux/fcntl.h>
 25 #include <linux/string.h>
 26 #include <linux/kernel.h>
 27 #include <linux/slab.h>
 28 #include <linux/mm.h>
 29 #include <linux/sunrpc/clnt.h>
 30 #include <linux/nfs_fs.h>
 31 #include <linux/nfs_mount.h>
 32 #include <linux/pagemap.h>
 33 #include <linux/pagevec.h>
 34 #include <linux/namei.h>
 35 #include <linux/mount.h>
 36 #include <linux/swap.h>
 37 #include <linux/sched.h>
 38 #include <linux/kmemleak.h>
 39 #include <linux/xattr.h>
 40 
 41 #include "delegation.h"
 42 #include "iostat.h"
 43 #include "internal.h"
 44 #include "fscache.h"
 45 
 46 #include "nfstrace.h"
 47 
 48 /* #define NFS_DEBUG_VERBOSE 1 */
 49 
 50 static int nfs_opendir(struct inode *, struct file *);
 51 static int nfs_closedir(struct inode *, struct file *);
 52 static int nfs_readdir(struct file *, struct dir_context *);
 53 static int nfs_fsync_dir(struct file *, loff_t, loff_t, int);
 54 static loff_t nfs_llseek_dir(struct file *, loff_t, int);
 55 static void nfs_readdir_clear_array(struct page*);
 56 
 57 const struct file_operations nfs_dir_operations = {
 58         .llseek         = nfs_llseek_dir,
 59         .read           = generic_read_dir,
 60         .iterate        = nfs_readdir,
 61         .open           = nfs_opendir,
 62         .release        = nfs_closedir,
 63         .fsync          = nfs_fsync_dir,
 64 };
 65 
 66 const struct address_space_operations nfs_dir_aops = {
 67         .freepage = nfs_readdir_clear_array,
 68 };
 69 
 70 static struct nfs_open_dir_context *alloc_nfs_open_dir_context(struct inode *dir, struct rpc_cred *cred)
 71 {
 72         struct nfs_inode *nfsi = NFS_I(dir);
 73         struct nfs_open_dir_context *ctx;
 74         ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
 75         if (ctx != NULL) {
 76                 ctx->duped = 0;
 77                 ctx->attr_gencount = nfsi->attr_gencount;
 78                 ctx->dir_cookie = 0;
 79                 ctx->dup_cookie = 0;
 80                 ctx->cred = get_rpccred(cred);
 81                 spin_lock(&dir->i_lock);
 82                 list_add(&ctx->list, &nfsi->open_files);
 83                 spin_unlock(&dir->i_lock);
 84                 return ctx;
 85         }
 86         return  ERR_PTR(-ENOMEM);
 87 }
 88 
 89 static void put_nfs_open_dir_context(struct inode *dir, struct nfs_open_dir_context *ctx)
 90 {
 91         spin_lock(&dir->i_lock);
 92         list_del(&ctx->list);
 93         spin_unlock(&dir->i_lock);
 94         put_rpccred(ctx->cred);
 95         kfree(ctx);
 96 }
 97 
 98 /*
 99  * Open file
100  */
101 static int
102 nfs_opendir(struct inode *inode, struct file *filp)
103 {
104         int res = 0;
105         struct nfs_open_dir_context *ctx;
106         struct rpc_cred *cred;
107 
108         dfprintk(FILE, "NFS: open dir(%pD2)\n", filp);
109 
110         nfs_inc_stats(inode, NFSIOS_VFSOPEN);
111 
112         cred = rpc_lookup_cred();
113         if (IS_ERR(cred))
114                 return PTR_ERR(cred);
115         ctx = alloc_nfs_open_dir_context(inode, cred);
116         if (IS_ERR(ctx)) {
117                 res = PTR_ERR(ctx);
118                 goto out;
119         }
120         filp->private_data = ctx;
121 out:
122         put_rpccred(cred);
123         return res;
124 }
125 
126 static int
127 nfs_closedir(struct inode *inode, struct file *filp)
128 {
129         put_nfs_open_dir_context(file_inode(filp), filp->private_data);
130         return 0;
131 }
132 
133 struct nfs_cache_array_entry {
134         u64 cookie;
135         u64 ino;
136         struct qstr string;
137         unsigned char d_type;
138 };
139 
140 struct nfs_cache_array {
141         int size;
142         int eof_index;
143         u64 last_cookie;
144         struct nfs_cache_array_entry array[0];
145 };
146 
147 typedef int (*decode_dirent_t)(struct xdr_stream *, struct nfs_entry *, bool);
148 typedef struct {
149         struct file     *file;
150         struct page     *page;
151         struct dir_context *ctx;
152         unsigned long   page_index;
153         u64             *dir_cookie;
154         u64             last_cookie;
155         loff_t          current_index;
156         decode_dirent_t decode;
157 
158         unsigned long   timestamp;
159         unsigned long   gencount;
160         unsigned int    cache_entry_index;
161         bool plus;
162         bool eof;
163 } nfs_readdir_descriptor_t;
164 
165 /*
166  * we are freeing strings created by nfs_add_to_readdir_array()
167  */
168 static
169 void nfs_readdir_clear_array(struct page *page)
170 {
171         struct nfs_cache_array *array;
172         int i;
173 
174         array = kmap_atomic(page);
175         for (i = 0; i < array->size; i++)
176                 kfree(array->array[i].string.name);
177         kunmap_atomic(array);
178 }
179 
180 /*
181  * the caller is responsible for freeing qstr.name
182  * when called by nfs_readdir_add_to_array, the strings will be freed in
183  * nfs_clear_readdir_array()
184  */
185 static
186 int nfs_readdir_make_qstr(struct qstr *string, const char *name, unsigned int len)
187 {
188         string->len = len;
189         string->name = kmemdup(name, len, GFP_KERNEL);
190         if (string->name == NULL)
191                 return -ENOMEM;
192         /*
193          * Avoid a kmemleak false positive. The pointer to the name is stored
194          * in a page cache page which kmemleak does not scan.
195          */
196         kmemleak_not_leak(string->name);
197         string->hash = full_name_hash(NULL, name, len);
198         return 0;
199 }
200 
201 static
202 int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
203 {
204         struct nfs_cache_array *array = kmap(page);
205         struct nfs_cache_array_entry *cache_entry;
206         int ret;
207 
208         cache_entry = &array->array[array->size];
209 
210         /* Check that this entry lies within the page bounds */
211         ret = -ENOSPC;
212         if ((char *)&cache_entry[1] - (char *)page_address(page) > PAGE_SIZE)
213                 goto out;
214 
215         cache_entry->cookie = entry->prev_cookie;
216         cache_entry->ino = entry->ino;
217         cache_entry->d_type = entry->d_type;
218         ret = nfs_readdir_make_qstr(&cache_entry->string, entry->name, entry->len);
219         if (ret)
220                 goto out;
221         array->last_cookie = entry->cookie;
222         array->size++;
223         if (entry->eof != 0)
224                 array->eof_index = array->size;
225 out:
226         kunmap(page);
227         return ret;
228 }
229 
230 static
231 int nfs_readdir_search_for_pos(struct nfs_cache_array *array, nfs_readdir_descriptor_t *desc)
232 {
233         loff_t diff = desc->ctx->pos - desc->current_index;
234         unsigned int index;
235 
236         if (diff < 0)
237                 goto out_eof;
238         if (diff >= array->size) {
239                 if (array->eof_index >= 0)
240                         goto out_eof;
241                 return -EAGAIN;
242         }
243 
244         index = (unsigned int)diff;
245         *desc->dir_cookie = array->array[index].cookie;
246         desc->cache_entry_index = index;
247         return 0;
248 out_eof:
249         desc->eof = true;
250         return -EBADCOOKIE;
251 }
252 
253 static bool
254 nfs_readdir_inode_mapping_valid(struct nfs_inode *nfsi)
255 {
256         if (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))
257                 return false;
258         smp_rmb();
259         return !test_bit(NFS_INO_INVALIDATING, &nfsi->flags);
260 }
261 
262 static
263 int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_descriptor_t *desc)
264 {
265         int i;
266         loff_t new_pos;
267         int status = -EAGAIN;
268 
269         for (i = 0; i < array->size; i++) {
270                 if (array->array[i].cookie == *desc->dir_cookie) {
271                         struct nfs_inode *nfsi = NFS_I(file_inode(desc->file));
272                         struct nfs_open_dir_context *ctx = desc->file->private_data;
273 
274                         new_pos = desc->current_index + i;
275                         if (ctx->attr_gencount != nfsi->attr_gencount ||
276                             !nfs_readdir_inode_mapping_valid(nfsi)) {
277                                 ctx->duped = 0;
278                                 ctx->attr_gencount = nfsi->attr_gencount;
279                         } else if (new_pos < desc->ctx->pos) {
280                                 if (ctx->duped > 0
281                                     && ctx->dup_cookie == *desc->dir_cookie) {
282                                         if (printk_ratelimit()) {
283                                                 pr_notice("NFS: directory %pD2 contains a readdir loop."
284                                                                 "Please contact your server vendor.  "
285                                                                 "The file: %.*s has duplicate cookie %llu\n",
286                                                                 desc->file, array->array[i].string.len,
287                                                                 array->array[i].string.name, *desc->dir_cookie);
288                                         }
289                                         status = -ELOOP;
290                                         goto out;
291                                 }
292                                 ctx->dup_cookie = *desc->dir_cookie;
293                                 ctx->duped = -1;
294                         }
295                         desc->ctx->pos = new_pos;
296                         desc->cache_entry_index = i;
297                         return 0;
298                 }
299         }
300         if (array->eof_index >= 0) {
301                 status = -EBADCOOKIE;
302                 if (*desc->dir_cookie == array->last_cookie)
303                         desc->eof = true;
304         }
305 out:
306         return status;
307 }
308 
309 static
310 int nfs_readdir_search_array(nfs_readdir_descriptor_t *desc)
311 {
312         struct nfs_cache_array *array;
313         int status;
314 
315         array = kmap(desc->page);
316 
317         if (*desc->dir_cookie == 0)
318                 status = nfs_readdir_search_for_pos(array, desc);
319         else
320                 status = nfs_readdir_search_for_cookie(array, desc);
321 
322         if (status == -EAGAIN) {
323                 desc->last_cookie = array->last_cookie;
324                 desc->current_index += array->size;
325                 desc->page_index++;
326         }
327         kunmap(desc->page);
328         return status;
329 }
330 
331 /* Fill a page with xdr information before transferring to the cache page */
332 static
333 int nfs_readdir_xdr_filler(struct page **pages, nfs_readdir_descriptor_t *desc,
334                         struct nfs_entry *entry, struct file *file, struct inode *inode)
335 {
336         struct nfs_open_dir_context *ctx = file->private_data;
337         struct rpc_cred *cred = ctx->cred;
338         unsigned long   timestamp, gencount;
339         int             error;
340 
341  again:
342         timestamp = jiffies;
343         gencount = nfs_inc_attr_generation_counter();
344         error = NFS_PROTO(inode)->readdir(file_dentry(file), cred, entry->cookie, pages,
345                                           NFS_SERVER(inode)->dtsize, desc->plus);
346         if (error < 0) {
347                 /* We requested READDIRPLUS, but the server doesn't grok it */
348                 if (error == -ENOTSUPP && desc->plus) {
349                         NFS_SERVER(inode)->caps &= ~NFS_CAP_READDIRPLUS;
350                         clear_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(inode)->flags);
351                         desc->plus = false;
352                         goto again;
353                 }
354                 goto error;
355         }
356         desc->timestamp = timestamp;
357         desc->gencount = gencount;
358 error:
359         return error;
360 }
361 
362 static int xdr_decode(nfs_readdir_descriptor_t *desc,
363                       struct nfs_entry *entry, struct xdr_stream *xdr)
364 {
365         int error;
366 
367         error = desc->decode(xdr, entry, desc->plus);
368         if (error)
369                 return error;
370         entry->fattr->time_start = desc->timestamp;
371         entry->fattr->gencount = desc->gencount;
372         return 0;
373 }
374 
375 /* Match file and dirent using either filehandle or fileid
376  * Note: caller is responsible for checking the fsid
377  */
378 static
379 int nfs_same_file(struct dentry *dentry, struct nfs_entry *entry)
380 {
381         struct inode *inode;
382         struct nfs_inode *nfsi;
383 
384         if (d_really_is_negative(dentry))
385                 return 0;
386 
387         inode = d_inode(dentry);
388         if (is_bad_inode(inode) || NFS_STALE(inode))
389                 return 0;
390 
391         nfsi = NFS_I(inode);
392         if (entry->fattr->fileid != nfsi->fileid)
393                 return 0;
394         if (entry->fh->size && nfs_compare_fh(entry->fh, &nfsi->fh) != 0)
395                 return 0;
396         return 1;
397 }
398 
399 static
400 bool nfs_use_readdirplus(struct inode *dir, struct dir_context *ctx)
401 {
402         if (!nfs_server_capable(dir, NFS_CAP_READDIRPLUS))
403                 return false;
404         if (test_and_clear_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(dir)->flags))
405                 return true;
406         if (ctx->pos == 0)
407                 return true;
408         return false;
409 }
410 
411 /*
412  * This function is called by the lookup and getattr code to request the
413  * use of readdirplus to accelerate any future lookups in the same
414  * directory.
415  */
416 void nfs_advise_use_readdirplus(struct inode *dir)
417 {
418         struct nfs_inode *nfsi = NFS_I(dir);
419 
420         if (nfs_server_capable(dir, NFS_CAP_READDIRPLUS) &&
421             !list_empty(&nfsi->open_files))
422                 set_bit(NFS_INO_ADVISE_RDPLUS, &nfsi->flags);
423 }
424 
425 /*
426  * This function is mainly for use by nfs_getattr().
427  *
428  * If this is an 'ls -l', we want to force use of readdirplus.
429  * Do this by checking if there is an active file descriptor
430  * and calling nfs_advise_use_readdirplus, then forcing a
431  * cache flush.
432  */
433 void nfs_force_use_readdirplus(struct inode *dir)
434 {
435         struct nfs_inode *nfsi = NFS_I(dir);
436 
437         if (nfs_server_capable(dir, NFS_CAP_READDIRPLUS) &&
438             !list_empty(&nfsi->open_files)) {
439                 set_bit(NFS_INO_ADVISE_RDPLUS, &nfsi->flags);
440                 invalidate_mapping_pages(dir->i_mapping, 0, -1);
441         }
442 }
443 
444 static
445 void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry)
446 {
447         struct qstr filename = QSTR_INIT(entry->name, entry->len);
448         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
449         struct dentry *dentry;
450         struct dentry *alias;
451         struct inode *dir = d_inode(parent);
452         struct inode *inode;
453         int status;
454 
455         if (!(entry->fattr->valid & NFS_ATTR_FATTR_FILEID))
456                 return;
457         if (!(entry->fattr->valid & NFS_ATTR_FATTR_FSID))
458                 return;
459         if (filename.len == 0)
460                 return;
461         /* Validate that the name doesn't contain any illegal '\0' */
462         if (strnlen(filename.name, filename.len) != filename.len)
463                 return;
464         /* ...or '/' */
465         if (strnchr(filename.name, filename.len, '/'))
466                 return;
467         if (filename.name[0] == '.') {
468                 if (filename.len == 1)
469                         return;
470                 if (filename.len == 2 && filename.name[1] == '.')
471                         return;
472         }
473         filename.hash = full_name_hash(parent, filename.name, filename.len);
474 
475         dentry = d_lookup(parent, &filename);
476 again:
477         if (!dentry) {
478                 dentry = d_alloc_parallel(parent, &filename, &wq);
479                 if (IS_ERR(dentry))
480                         return;
481         }
482         if (!d_in_lookup(dentry)) {
483                 /* Is there a mountpoint here? If so, just exit */
484                 if (!nfs_fsid_equal(&NFS_SB(dentry->d_sb)->fsid,
485                                         &entry->fattr->fsid))
486                         goto out;
487                 if (nfs_same_file(dentry, entry)) {
488                         if (!entry->fh->size)
489                                 goto out;
490                         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
491                         status = nfs_refresh_inode(d_inode(dentry), entry->fattr);
492                         if (!status)
493                                 nfs_setsecurity(d_inode(dentry), entry->fattr, entry->label);
494                         goto out;
495                 } else {
496                         d_invalidate(dentry);
497                         dput(dentry);
498                         dentry = NULL;
499                         goto again;
500                 }
501         }
502         if (!entry->fh->size) {
503                 d_lookup_done(dentry);
504                 goto out;
505         }
506 
507         inode = nfs_fhget(dentry->d_sb, entry->fh, entry->fattr, entry->label);
508         alias = d_splice_alias(inode, dentry);
509         d_lookup_done(dentry);
510         if (alias) {
511                 if (IS_ERR(alias))
512                         goto out;
513                 dput(dentry);
514                 dentry = alias;
515         }
516         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
517 out:
518         dput(dentry);
519 }
520 
521 /* Perform conversion from xdr to cache array */
522 static
523 int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *entry,
524                                 struct page **xdr_pages, struct page *page, unsigned int buflen)
525 {
526         struct xdr_stream stream;
527         struct xdr_buf buf;
528         struct page *scratch;
529         struct nfs_cache_array *array;
530         unsigned int count = 0;
531         int status;
532 
533         scratch = alloc_page(GFP_KERNEL);
534         if (scratch == NULL)
535                 return -ENOMEM;
536 
537         if (buflen == 0)
538                 goto out_nopages;
539 
540         xdr_init_decode_pages(&stream, &buf, xdr_pages, buflen);
541         xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);
542 
543         do {
544                 status = xdr_decode(desc, entry, &stream);
545                 if (status != 0) {
546                         if (status == -EAGAIN)
547                                 status = 0;
548                         break;
549                 }
550 
551                 count++;
552 
553                 if (desc->plus)
554                         nfs_prime_dcache(file_dentry(desc->file), entry);
555 
556                 status = nfs_readdir_add_to_array(entry, page);
557                 if (status != 0)
558                         break;
559         } while (!entry->eof);
560 
561 out_nopages:
562         if (count == 0 || (status == -EBADCOOKIE && entry->eof != 0)) {
563                 array = kmap(page);
564                 array->eof_index = array->size;
565                 status = 0;
566                 kunmap(page);
567         }
568 
569         put_page(scratch);
570         return status;
571 }
572 
573 static
574 void nfs_readdir_free_pages(struct page **pages, unsigned int npages)
575 {
576         unsigned int i;
577         for (i = 0; i < npages; i++)
578                 put_page(pages[i]);
579 }
580 
581 /*
582  * nfs_readdir_large_page will allocate pages that must be freed with a call
583  * to nfs_readdir_free_pagearray
584  */
585 static
586 int nfs_readdir_alloc_pages(struct page **pages, unsigned int npages)
587 {
588         unsigned int i;
589 
590         for (i = 0; i < npages; i++) {
591                 struct page *page = alloc_page(GFP_KERNEL);
592                 if (page == NULL)
593                         goto out_freepages;
594                 pages[i] = page;
595         }
596         return 0;
597 
598 out_freepages:
599         nfs_readdir_free_pages(pages, i);
600         return -ENOMEM;
601 }
602 
603 static
604 int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page, struct inode *inode)
605 {
606         struct page *pages[NFS_MAX_READDIR_PAGES];
607         struct nfs_entry entry;
608         struct file     *file = desc->file;
609         struct nfs_cache_array *array;
610         int status = -ENOMEM;
611         unsigned int array_size = ARRAY_SIZE(pages);
612 
613         entry.prev_cookie = 0;
614         entry.cookie = desc->last_cookie;
615         entry.eof = 0;
616         entry.fh = nfs_alloc_fhandle();
617         entry.fattr = nfs_alloc_fattr();
618         entry.server = NFS_SERVER(inode);
619         if (entry.fh == NULL || entry.fattr == NULL)
620                 goto out;
621 
622         entry.label = nfs4_label_alloc(NFS_SERVER(inode), GFP_NOWAIT);
623         if (IS_ERR(entry.label)) {
624                 status = PTR_ERR(entry.label);
625                 goto out;
626         }
627 
628         array = kmap(page);
629         memset(array, 0, sizeof(struct nfs_cache_array));
630         array->eof_index = -1;
631 
632         status = nfs_readdir_alloc_pages(pages, array_size);
633         if (status < 0)
634                 goto out_release_array;
635         do {
636                 unsigned int pglen;
637                 status = nfs_readdir_xdr_filler(pages, desc, &entry, file, inode);
638 
639                 if (status < 0)
640                         break;
641                 pglen = status;
642                 status = nfs_readdir_page_filler(desc, &entry, pages, page, pglen);
643                 if (status < 0) {
644                         if (status == -ENOSPC)
645                                 status = 0;
646                         break;
647                 }
648         } while (array->eof_index < 0);
649 
650         nfs_readdir_free_pages(pages, array_size);
651 out_release_array:
652         kunmap(page);
653         nfs4_label_free(entry.label);
654 out:
655         nfs_free_fattr(entry.fattr);
656         nfs_free_fhandle(entry.fh);
657         return status;
658 }
659 
660 /*
661  * Now we cache directories properly, by converting xdr information
662  * to an array that can be used for lookups later.  This results in
663  * fewer cache pages, since we can store more information on each page.
664  * We only need to convert from xdr once so future lookups are much simpler
665  */
666 static
667 int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page* page)
668 {
669         struct inode    *inode = file_inode(desc->file);
670         int ret;
671 
672         ret = nfs_readdir_xdr_to_array(desc, page, inode);
673         if (ret < 0)
674                 goto error;
675         SetPageUptodate(page);
676 
677         if (invalidate_inode_pages2_range(inode->i_mapping, page->index + 1, -1) < 0) {
678                 /* Should never happen */
679                 nfs_zap_mapping(inode, inode->i_mapping);
680         }
681         unlock_page(page);
682         return 0;
683  error:
684         unlock_page(page);
685         return ret;
686 }
687 
688 static
689 void cache_page_release(nfs_readdir_descriptor_t *desc)
690 {
691         if (!desc->page->mapping)
692                 nfs_readdir_clear_array(desc->page);
693         put_page(desc->page);
694         desc->page = NULL;
695 }
696 
697 static
698 struct page *get_cache_page(nfs_readdir_descriptor_t *desc)
699 {
700         return read_cache_page(desc->file->f_mapping,
701                         desc->page_index, (filler_t *)nfs_readdir_filler, desc);
702 }
703 
704 /*
705  * Returns 0 if desc->dir_cookie was found on page desc->page_index
706  */
707 static
708 int find_cache_page(nfs_readdir_descriptor_t *desc)
709 {
710         int res;
711 
712         desc->page = get_cache_page(desc);
713         if (IS_ERR(desc->page))
714                 return PTR_ERR(desc->page);
715 
716         res = nfs_readdir_search_array(desc);
717         if (res != 0)
718                 cache_page_release(desc);
719         return res;
720 }
721 
722 /* Search for desc->dir_cookie from the beginning of the page cache */
723 static inline
724 int readdir_search_pagecache(nfs_readdir_descriptor_t *desc)
725 {
726         int res;
727 
728         if (desc->page_index == 0) {
729                 desc->current_index = 0;
730                 desc->last_cookie = 0;
731         }
732         do {
733                 res = find_cache_page(desc);
734         } while (res == -EAGAIN);
735         return res;
736 }
737 
738 /*
739  * Once we've found the start of the dirent within a page: fill 'er up...
740  */
741 static 
742 int nfs_do_filldir(nfs_readdir_descriptor_t *desc)
743 {
744         struct file     *file = desc->file;
745         int i = 0;
746         int res = 0;
747         struct nfs_cache_array *array = NULL;
748         struct nfs_open_dir_context *ctx = file->private_data;
749 
750         array = kmap(desc->page);
751         for (i = desc->cache_entry_index; i < array->size; i++) {
752                 struct nfs_cache_array_entry *ent;
753 
754                 ent = &array->array[i];
755                 if (!dir_emit(desc->ctx, ent->string.name, ent->string.len,
756                     nfs_compat_user_ino64(ent->ino), ent->d_type)) {
757                         desc->eof = true;
758                         break;
759                 }
760                 desc->ctx->pos++;
761                 if (i < (array->size-1))
762                         *desc->dir_cookie = array->array[i+1].cookie;
763                 else
764                         *desc->dir_cookie = array->last_cookie;
765                 if (ctx->duped != 0)
766                         ctx->duped = 1;
767         }
768         if (array->eof_index >= 0)
769                 desc->eof = true;
770 
771         kunmap(desc->page);
772         cache_page_release(desc);
773         dfprintk(DIRCACHE, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n",
774                         (unsigned long long)*desc->dir_cookie, res);
775         return res;
776 }
777 
778 /*
779  * If we cannot find a cookie in our cache, we suspect that this is
780  * because it points to a deleted file, so we ask the server to return
781  * whatever it thinks is the next entry. We then feed this to filldir.
782  * If all goes well, we should then be able to find our way round the
783  * cache on the next call to readdir_search_pagecache();
784  *
785  * NOTE: we cannot add the anonymous page to the pagecache because
786  *       the data it contains might not be page aligned. Besides,
787  *       we should already have a complete representation of the
788  *       directory in the page cache by the time we get here.
789  */
790 static inline
791 int uncached_readdir(nfs_readdir_descriptor_t *desc)
792 {
793         struct page     *page = NULL;
794         int             status;
795         struct inode *inode = file_inode(desc->file);
796         struct nfs_open_dir_context *ctx = desc->file->private_data;
797 
798         dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie %Lu\n",
799                         (unsigned long long)*desc->dir_cookie);
800 
801         page = alloc_page(GFP_HIGHUSER);
802         if (!page) {
803                 status = -ENOMEM;
804                 goto out;
805         }
806 
807         desc->page_index = 0;
808         desc->last_cookie = *desc->dir_cookie;
809         desc->page = page;
810         ctx->duped = 0;
811 
812         status = nfs_readdir_xdr_to_array(desc, page, inode);
813         if (status < 0)
814                 goto out_release;
815 
816         status = nfs_do_filldir(desc);
817 
818  out:
819         dfprintk(DIRCACHE, "NFS: %s: returns %d\n",
820                         __func__, status);
821         return status;
822  out_release:
823         cache_page_release(desc);
824         goto out;
825 }
826 
827 /* The file offset position represents the dirent entry number.  A
828    last cookie cache takes care of the common case of reading the
829    whole directory.
830  */
831 static int nfs_readdir(struct file *file, struct dir_context *ctx)
832 {
833         struct dentry   *dentry = file_dentry(file);
834         struct inode    *inode = d_inode(dentry);
835         nfs_readdir_descriptor_t my_desc,
836                         *desc = &my_desc;
837         struct nfs_open_dir_context *dir_ctx = file->private_data;
838         int res = 0;
839 
840         dfprintk(FILE, "NFS: readdir(%pD2) starting at cookie %llu\n",
841                         file, (long long)ctx->pos);
842         nfs_inc_stats(inode, NFSIOS_VFSGETDENTS);
843 
844         /*
845          * ctx->pos points to the dirent entry number.
846          * *desc->dir_cookie has the cookie for the next entry. We have
847          * to either find the entry with the appropriate number or
848          * revalidate the cookie.
849          */
850         memset(desc, 0, sizeof(*desc));
851 
852         desc->file = file;
853         desc->ctx = ctx;
854         desc->dir_cookie = &dir_ctx->dir_cookie;
855         desc->decode = NFS_PROTO(inode)->decode_dirent;
856         desc->plus = nfs_use_readdirplus(inode, ctx);
857 
858         if (ctx->pos == 0 || nfs_attribute_cache_expired(inode))
859                 res = nfs_revalidate_mapping(inode, file->f_mapping);
860         if (res < 0)
861                 goto out;
862 
863         do {
864                 res = readdir_search_pagecache(desc);
865 
866                 if (res == -EBADCOOKIE) {
867                         res = 0;
868                         /* This means either end of directory */
869                         if (*desc->dir_cookie && !desc->eof) {
870                                 /* Or that the server has 'lost' a cookie */
871                                 res = uncached_readdir(desc);
872                                 if (res == 0)
873                                         continue;
874                         }
875                         break;
876                 }
877                 if (res == -ETOOSMALL && desc->plus) {
878                         clear_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(inode)->flags);
879                         nfs_zap_caches(inode);
880                         desc->page_index = 0;
881                         desc->plus = false;
882                         desc->eof = false;
883                         continue;
884                 }
885                 if (res < 0)
886                         break;
887 
888                 res = nfs_do_filldir(desc);
889                 if (res < 0)
890                         break;
891         } while (!desc->eof);
892 out:
893         if (res > 0)
894                 res = 0;
895         dfprintk(FILE, "NFS: readdir(%pD2) returns %d\n", file, res);
896         return res;
897 }
898 
899 static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence)
900 {
901         struct inode *inode = file_inode(filp);
902         struct nfs_open_dir_context *dir_ctx = filp->private_data;
903 
904         dfprintk(FILE, "NFS: llseek dir(%pD2, %lld, %d)\n",
905                         filp, offset, whence);
906 
907         inode_lock(inode);
908         switch (whence) {
909                 case 1:
910                         offset += filp->f_pos;
911                 case 0:
912                         if (offset >= 0)
913                                 break;
914                 default:
915                         offset = -EINVAL;
916                         goto out;
917         }
918         if (offset != filp->f_pos) {
919                 filp->f_pos = offset;
920                 dir_ctx->dir_cookie = 0;
921                 dir_ctx->duped = 0;
922         }
923 out:
924         inode_unlock(inode);
925         return offset;
926 }
927 
928 /*
929  * All directory operations under NFS are synchronous, so fsync()
930  * is a dummy operation.
931  */
932 static int nfs_fsync_dir(struct file *filp, loff_t start, loff_t end,
933                          int datasync)
934 {
935         struct inode *inode = file_inode(filp);
936 
937         dfprintk(FILE, "NFS: fsync dir(%pD2) datasync %d\n", filp, datasync);
938 
939         inode_lock(inode);
940         nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
941         inode_unlock(inode);
942         return 0;
943 }
944 
945 /**
946  * nfs_force_lookup_revalidate - Mark the directory as having changed
947  * @dir - pointer to directory inode
948  *
949  * This forces the revalidation code in nfs_lookup_revalidate() to do a
950  * full lookup on all child dentries of 'dir' whenever a change occurs
951  * on the server that might have invalidated our dcache.
952  *
953  * The caller should be holding dir->i_lock
954  */
955 void nfs_force_lookup_revalidate(struct inode *dir)
956 {
957         NFS_I(dir)->cache_change_attribute++;
958 }
959 EXPORT_SYMBOL_GPL(nfs_force_lookup_revalidate);
960 
961 /*
962  * A check for whether or not the parent directory has changed.
963  * In the case it has, we assume that the dentries are untrustworthy
964  * and may need to be looked up again.
965  * If rcu_walk prevents us from performing a full check, return 0.
966  */
967 static int nfs_check_verifier(struct inode *dir, struct dentry *dentry,
968                               int rcu_walk)
969 {
970         if (IS_ROOT(dentry))
971                 return 1;
972         if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
973                 return 0;
974         if (!nfs_verify_change_attribute(dir, dentry->d_time))
975                 return 0;
976         /* Revalidate nfsi->cache_change_attribute before we declare a match */
977         if (nfs_mapping_need_revalidate_inode(dir)) {
978                 if (rcu_walk)
979                         return 0;
980                 if (__nfs_revalidate_inode(NFS_SERVER(dir), dir) < 0)
981                         return 0;
982         }
983         if (!nfs_verify_change_attribute(dir, dentry->d_time))
984                 return 0;
985         return 1;
986 }
987 
988 /*
989  * Use intent information to check whether or not we're going to do
990  * an O_EXCL create using this path component.
991  */
992 static int nfs_is_exclusive_create(struct inode *dir, unsigned int flags)
993 {
994         if (NFS_PROTO(dir)->version == 2)
995                 return 0;
996         return flags & LOOKUP_EXCL;
997 }
998 
999 /*
1000  * Inode and filehandle revalidation for lookups.
1001  *
1002  * We force revalidation in the cases where the VFS sets LOOKUP_REVAL,
1003  * or if the intent information indicates that we're about to open this
1004  * particular file and the "nocto" mount flag is not set.
1005  *
1006  */
1007 static
1008 int nfs_lookup_verify_inode(struct inode *inode, unsigned int flags)
1009 {
1010         struct nfs_server *server = NFS_SERVER(inode);
1011         int ret;
1012 
1013         if (IS_AUTOMOUNT(inode))
1014                 return 0;
1015         /* VFS wants an on-the-wire revalidation */
1016         if (flags & LOOKUP_REVAL)
1017                 goto out_force;
1018         /* This is an open(2) */
1019         if ((flags & LOOKUP_OPEN) && !(server->flags & NFS_MOUNT_NOCTO) &&
1020             (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
1021                 goto out_force;
1022 out:
1023         return (inode->i_nlink == 0) ? -ENOENT : 0;
1024 out_force:
1025         if (flags & LOOKUP_RCU)
1026                 return -ECHILD;
1027         ret = __nfs_revalidate_inode(server, inode);
1028         if (ret != 0)
1029                 return ret;
1030         goto out;
1031 }
1032 
1033 /*
1034  * We judge how long we want to trust negative
1035  * dentries by looking at the parent inode mtime.
1036  *
1037  * If parent mtime has changed, we revalidate, else we wait for a
1038  * period corresponding to the parent's attribute cache timeout value.
1039  *
1040  * If LOOKUP_RCU prevents us from performing a full check, return 1
1041  * suggesting a reval is needed.
1042  */
1043 static inline
1044 int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry,
1045                        unsigned int flags)
1046 {
1047         /* Don't revalidate a negative dentry if we're creating a new file */
1048         if (flags & LOOKUP_CREATE)
1049                 return 0;
1050         if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG)
1051                 return 1;
1052         return !nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU);
1053 }
1054 
1055 /*
1056  * This is called every time the dcache has a lookup hit,
1057  * and we should check whether we can really trust that
1058  * lookup.
1059  *
1060  * NOTE! The hit can be a negative hit too, don't assume
1061  * we have an inode!
1062  *
1063  * If the parent directory is seen to have changed, we throw out the
1064  * cached dentry and do a new lookup.
1065  */
1066 static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
1067 {
1068         struct inode *dir;
1069         struct inode *inode;
1070         struct dentry *parent;
1071         struct nfs_fh *fhandle = NULL;
1072         struct nfs_fattr *fattr = NULL;
1073         struct nfs4_label *label = NULL;
1074         int error;
1075 
1076         if (flags & LOOKUP_RCU) {
1077                 parent = READ_ONCE(dentry->d_parent);
1078                 dir = d_inode_rcu(parent);
1079                 if (!dir)
1080                         return -ECHILD;
1081         } else {
1082                 parent = dget_parent(dentry);
1083                 dir = d_inode(parent);
1084         }
1085         nfs_inc_stats(dir, NFSIOS_DENTRYREVALIDATE);
1086         inode = d_inode(dentry);
1087 
1088         if (!inode) {
1089                 if (nfs_neg_need_reval(dir, dentry, flags)) {
1090                         if (flags & LOOKUP_RCU)
1091                                 return -ECHILD;
1092                         goto out_bad;
1093                 }
1094                 goto out_valid;
1095         }
1096 
1097         if (is_bad_inode(inode)) {
1098                 if (flags & LOOKUP_RCU)
1099                         return -ECHILD;
1100                 dfprintk(LOOKUPCACHE, "%s: %pd2 has dud inode\n",
1101                                 __func__, dentry);
1102                 goto out_bad;
1103         }
1104 
1105         if (NFS_PROTO(dir)->have_delegation(inode, FMODE_READ))
1106                 goto out_set_verifier;
1107 
1108         /* Force a full look up iff the parent directory has changed */
1109         if (!nfs_is_exclusive_create(dir, flags) &&
1110             nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) {
1111                 error = nfs_lookup_verify_inode(inode, flags);
1112                 if (error) {
1113                         if (flags & LOOKUP_RCU)
1114                                 return -ECHILD;
1115                         if (error == -ESTALE)
1116                                 goto out_zap_parent;
1117                         goto out_error;
1118                 }
1119                 nfs_advise_use_readdirplus(dir);
1120                 goto out_valid;
1121         }
1122 
1123         if (flags & LOOKUP_RCU)
1124                 return -ECHILD;
1125 
1126         if (NFS_STALE(inode))
1127                 goto out_bad;
1128 
1129         error = -ENOMEM;
1130         fhandle = nfs_alloc_fhandle();
1131         fattr = nfs_alloc_fattr();
1132         if (fhandle == NULL || fattr == NULL)
1133                 goto out_error;
1134 
1135         label = nfs4_label_alloc(NFS_SERVER(inode), GFP_NOWAIT);
1136         if (IS_ERR(label))
1137                 goto out_error;
1138 
1139         trace_nfs_lookup_revalidate_enter(dir, dentry, flags);
1140         error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, label);
1141         trace_nfs_lookup_revalidate_exit(dir, dentry, flags, error);
1142         if (error == -ESTALE || error == -ENOENT)
1143                 goto out_bad;
1144         if (error)
1145                 goto out_error;
1146         if (nfs_compare_fh(NFS_FH(inode), fhandle))
1147                 goto out_bad;
1148         if ((error = nfs_refresh_inode(inode, fattr)) != 0)
1149                 goto out_bad;
1150 
1151         nfs_setsecurity(inode, fattr, label);
1152 
1153         nfs_free_fattr(fattr);
1154         nfs_free_fhandle(fhandle);
1155         nfs4_label_free(label);
1156 
1157         /* set a readdirplus hint that we had a cache miss */
1158         nfs_force_use_readdirplus(dir);
1159 
1160 out_set_verifier:
1161         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
1162  out_valid:
1163         if (flags & LOOKUP_RCU) {
1164                 if (parent != READ_ONCE(dentry->d_parent))
1165                         return -ECHILD;
1166         } else
1167                 dput(parent);
1168         dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is valid\n",
1169                         __func__, dentry);
1170         return 1;
1171 out_zap_parent:
1172         nfs_zap_caches(dir);
1173  out_bad:
1174         WARN_ON(flags & LOOKUP_RCU);
1175         nfs_free_fattr(fattr);
1176         nfs_free_fhandle(fhandle);
1177         nfs4_label_free(label);
1178         nfs_mark_for_revalidate(dir);
1179         if (inode && S_ISDIR(inode->i_mode)) {
1180                 /* Purge readdir caches. */
1181                 nfs_zap_caches(inode);
1182                 /*
1183                  * We can't d_drop the root of a disconnected tree:
1184                  * its d_hash is on the s_anon list and d_drop() would hide
1185                  * it from shrink_dcache_for_unmount(), leading to busy
1186                  * inodes on unmount and further oopses.
1187                  */
1188                 if (IS_ROOT(dentry))
1189                         goto out_valid;
1190         }
1191         dput(parent);
1192         dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is invalid\n",
1193                         __func__, dentry);
1194         return 0;
1195 out_error:
1196         WARN_ON(flags & LOOKUP_RCU);
1197         nfs_free_fattr(fattr);
1198         nfs_free_fhandle(fhandle);
1199         nfs4_label_free(label);
1200         dput(parent);
1201         dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) lookup returned error %d\n",
1202                         __func__, dentry, error);
1203         return error;
1204 }
1205 
1206 /*
1207  * A weaker form of d_revalidate for revalidating just the d_inode(dentry)
1208  * when we don't really care about the dentry name. This is called when a
1209  * pathwalk ends on a dentry that was not found via a normal lookup in the
1210  * parent dir (e.g.: ".", "..", procfs symlinks or mountpoint traversals).
1211  *
1212  * In this situation, we just want to verify that the inode itself is OK
1213  * since the dentry might have changed on the server.
1214  */
1215 static int nfs_weak_revalidate(struct dentry *dentry, unsigned int flags)
1216 {
1217         struct inode *inode = d_inode(dentry);
1218         int error = 0;
1219 
1220         /*
1221          * I believe we can only get a negative dentry here in the case of a
1222          * procfs-style symlink. Just assume it's correct for now, but we may
1223          * eventually need to do something more here.
1224          */
1225         if (!inode) {
1226                 dfprintk(LOOKUPCACHE, "%s: %pd2 has negative inode\n",
1227                                 __func__, dentry);
1228                 return 1;
1229         }
1230 
1231         if (is_bad_inode(inode)) {
1232                 dfprintk(LOOKUPCACHE, "%s: %pd2 has dud inode\n",
1233                                 __func__, dentry);
1234                 return 0;
1235         }
1236 
1237         error = nfs_lookup_verify_inode(inode, flags);
1238         dfprintk(LOOKUPCACHE, "NFS: %s: inode %lu is %s\n",
1239                         __func__, inode->i_ino, error ? "invalid" : "valid");
1240         return !error;
1241 }
1242 
1243 /*
1244  * This is called from dput() when d_count is going to 0.
1245  */
1246 static int nfs_dentry_delete(const struct dentry *dentry)
1247 {
1248         dfprintk(VFS, "NFS: dentry_delete(%pd2, %x)\n",
1249                 dentry, dentry->d_flags);
1250 
1251         /* Unhash any dentry with a stale inode */
1252         if (d_really_is_positive(dentry) && NFS_STALE(d_inode(dentry)))
1253                 return 1;
1254 
1255         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
1256                 /* Unhash it, so that ->d_iput() would be called */
1257                 return 1;
1258         }
1259         if (!(dentry->d_sb->s_flags & SB_ACTIVE)) {
1260                 /* Unhash it, so that ancestors of killed async unlink
1261                  * files will be cleaned up during umount */
1262                 return 1;
1263         }
1264         return 0;
1265 
1266 }
1267 
1268 /* Ensure that we revalidate inode->i_nlink */
1269 static void nfs_drop_nlink(struct inode *inode)
1270 {
1271         spin_lock(&inode->i_lock);
1272         /* drop the inode if we're reasonably sure this is the last link */
1273         if (inode->i_nlink == 1)
1274                 clear_nlink(inode);
1275         NFS_I(inode)->cache_validity |= NFS_INO_INVALID_CHANGE
1276                 | NFS_INO_INVALID_CTIME
1277                 | NFS_INO_INVALID_OTHER;
1278         spin_unlock(&inode->i_lock);
1279 }
1280 
1281 /*
1282  * Called when the dentry loses inode.
1283  * We use it to clean up silly-renamed files.
1284  */
1285 static void nfs_dentry_iput(struct dentry *dentry, struct inode *inode)
1286 {
1287         if (S_ISDIR(inode->i_mode))
1288                 /* drop any readdir cache as it could easily be old */
1289                 NFS_I(inode)->cache_validity |= NFS_INO_INVALID_DATA;
1290 
1291         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
1292                 nfs_complete_unlink(dentry, inode);
1293                 nfs_drop_nlink(inode);
1294         }
1295         iput(inode);
1296 }
1297 
1298 static void nfs_d_release(struct dentry *dentry)
1299 {
1300         /* free cached devname value, if it survived that far */
1301         if (unlikely(dentry->d_fsdata)) {
1302                 if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
1303                         WARN_ON(1);
1304                 else
1305                         kfree(dentry->d_fsdata);
1306         }
1307 }
1308 
1309 const struct dentry_operations nfs_dentry_operations = {
1310         .d_revalidate   = nfs_lookup_revalidate,
1311         .d_weak_revalidate      = nfs_weak_revalidate,
1312         .d_delete       = nfs_dentry_delete,
1313         .d_iput         = nfs_dentry_iput,
1314         .d_automount    = nfs_d_automount,
1315         .d_release      = nfs_d_release,
1316 };
1317 EXPORT_SYMBOL_GPL(nfs_dentry_operations);
1318 
1319 struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
1320 {
1321         struct dentry *res;
1322         struct inode *inode = NULL;
1323         struct nfs_fh *fhandle = NULL;
1324         struct nfs_fattr *fattr = NULL;
1325         struct nfs4_label *label = NULL;
1326         int error;
1327 
1328         dfprintk(VFS, "NFS: lookup(%pd2)\n", dentry);
1329         nfs_inc_stats(dir, NFSIOS_VFSLOOKUP);
1330 
1331         if (unlikely(dentry->d_name.len > NFS_SERVER(dir)->namelen))
1332                 return ERR_PTR(-ENAMETOOLONG);
1333 
1334         /*
1335          * If we're doing an exclusive create, optimize away the lookup
1336          * but don't hash the dentry.
1337          */
1338         if (nfs_is_exclusive_create(dir, flags))
1339                 return NULL;
1340 
1341         res = ERR_PTR(-ENOMEM);
1342         fhandle = nfs_alloc_fhandle();
1343         fattr = nfs_alloc_fattr();
1344         if (fhandle == NULL || fattr == NULL)
1345                 goto out;
1346 
1347         label = nfs4_label_alloc(NFS_SERVER(dir), GFP_NOWAIT);
1348         if (IS_ERR(label))
1349                 goto out;
1350 
1351         trace_nfs_lookup_enter(dir, dentry, flags);
1352         error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, label);
1353         if (error == -ENOENT)
1354                 goto no_entry;
1355         if (error < 0) {
1356                 res = ERR_PTR(error);
1357                 goto out_label;
1358         }
1359         inode = nfs_fhget(dentry->d_sb, fhandle, fattr, label);
1360         res = ERR_CAST(inode);
1361         if (IS_ERR(res))
1362                 goto out_label;
1363 
1364         /* Notify readdir to use READDIRPLUS */
1365         nfs_force_use_readdirplus(dir);
1366 
1367 no_entry:
1368         res = d_splice_alias(inode, dentry);
1369         if (res != NULL) {
1370                 if (IS_ERR(res))
1371                         goto out_label;
1372                 dentry = res;
1373         }
1374         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
1375 out_label:
1376         trace_nfs_lookup_exit(dir, dentry, flags, error);
1377         nfs4_label_free(label);
1378 out:
1379         nfs_free_fattr(fattr);
1380         nfs_free_fhandle(fhandle);
1381         return res;
1382 }
1383 EXPORT_SYMBOL_GPL(nfs_lookup);
1384 
1385 #if IS_ENABLED(CONFIG_NFS_V4)
1386 static int nfs4_lookup_revalidate(struct dentry *, unsigned int);
1387 
1388 const struct dentry_operations nfs4_dentry_operations = {
1389         .d_revalidate   = nfs4_lookup_revalidate,
1390         .d_weak_revalidate      = nfs_weak_revalidate,
1391         .d_delete       = nfs_dentry_delete,
1392         .d_iput         = nfs_dentry_iput,
1393         .d_automount    = nfs_d_automount,
1394         .d_release      = nfs_d_release,
1395 };
1396 EXPORT_SYMBOL_GPL(nfs4_dentry_operations);
1397 
1398 static fmode_t flags_to_mode(int flags)
1399 {
1400         fmode_t res = (__force fmode_t)flags & FMODE_EXEC;
1401         if ((flags & O_ACCMODE) != O_WRONLY)
1402                 res |= FMODE_READ;
1403         if ((flags & O_ACCMODE) != O_RDONLY)
1404                 res |= FMODE_WRITE;
1405         return res;
1406 }
1407 
1408 static struct nfs_open_context *create_nfs_open_context(struct dentry *dentry, int open_flags, struct file *filp)
1409 {
1410         return alloc_nfs_open_context(dentry, flags_to_mode(open_flags), filp);
1411 }
1412 
1413 static int do_open(struct inode *inode, struct file *filp)
1414 {
1415         nfs_fscache_open_file(inode, filp);
1416         return 0;
1417 }
1418 
1419 static int nfs_finish_open(struct nfs_open_context *ctx,
1420                            struct dentry *dentry,
1421                            struct file *file, unsigned open_flags,
1422                            int *opened)
1423 {
1424         int err;
1425 
1426         err = finish_open(file, dentry, do_open, opened);
1427         if (err)
1428                 goto out;
1429         if (S_ISREG(file->f_path.dentry->d_inode->i_mode))
1430                 nfs_file_set_open_context(file, ctx);
1431         else
1432                 err = -ESTALE;
1433 out:
1434         return err;
1435 }
1436 
1437 int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
1438                     struct file *file, unsigned open_flags,
1439                     umode_t mode, int *opened)
1440 {
1441         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
1442         struct nfs_open_context *ctx;
1443         struct dentry *res;
1444         struct iattr attr = { .ia_valid = ATTR_OPEN };
1445         struct inode *inode;
1446         unsigned int lookup_flags = 0;
1447         bool switched = false;
1448         int err;
1449 
1450         /* Expect a negative dentry */
1451         BUG_ON(d_inode(dentry));
1452 
1453         dfprintk(VFS, "NFS: atomic_open(%s/%lu), %pd\n",
1454                         dir->i_sb->s_id, dir->i_ino, dentry);
1455 
1456         err = nfs_check_flags(open_flags);
1457         if (err)
1458                 return err;
1459 
1460         /* NFS only supports OPEN on regular files */
1461         if ((open_flags & O_DIRECTORY)) {
1462                 if (!d_in_lookup(dentry)) {
1463                         /*
1464                          * Hashed negative dentry with O_DIRECTORY: dentry was
1465                          * revalidated and is fine, no need to perform lookup
1466                          * again
1467                          */
1468                         return -ENOENT;
1469                 }
1470                 lookup_flags = LOOKUP_OPEN|LOOKUP_DIRECTORY;
1471                 goto no_open;
1472         }
1473 
1474         if (dentry->d_name.len > NFS_SERVER(dir)->namelen)
1475                 return -ENAMETOOLONG;
1476 
1477         if (open_flags & O_CREAT) {
1478                 struct nfs_server *server = NFS_SERVER(dir);
1479 
1480                 if (!(server->attr_bitmask[2] & FATTR4_WORD2_MODE_UMASK))
1481                         mode &= ~current_umask();
1482 
1483                 attr.ia_valid |= ATTR_MODE;
1484                 attr.ia_mode = mode;
1485         }
1486         if (open_flags & O_TRUNC) {
1487                 attr.ia_valid |= ATTR_SIZE;
1488                 attr.ia_size = 0;
1489         }
1490 
1491         if (!(open_flags & O_CREAT) && !d_in_lookup(dentry)) {
1492                 d_drop(dentry);
1493                 switched = true;
1494                 dentry = d_alloc_parallel(dentry->d_parent,
1495                                           &dentry->d_name, &wq);
1496                 if (IS_ERR(dentry))
1497                         return PTR_ERR(dentry);
1498                 if (unlikely(!d_in_lookup(dentry)))
1499                         return finish_no_open(file, dentry);
1500         }
1501 
1502         ctx = create_nfs_open_context(dentry, open_flags, file);
1503         err = PTR_ERR(ctx);
1504         if (IS_ERR(ctx))
1505                 goto out;
1506 
1507         trace_nfs_atomic_open_enter(dir, ctx, open_flags);
1508         inode = NFS_PROTO(dir)->open_context(dir, ctx, open_flags, &attr, opened);
1509         if (IS_ERR(inode)) {
1510                 err = PTR_ERR(inode);
1511                 trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
1512                 put_nfs_open_context(ctx);
1513                 d_drop(dentry);
1514                 switch (err) {
1515                 case -ENOENT:
1516                         d_splice_alias(NULL, dentry);
1517                         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
1518                         break;
1519                 case -EISDIR:
1520                 case -ENOTDIR:
1521                         goto no_open;
1522                 case -ELOOP:
1523                         if (!(open_flags & O_NOFOLLOW))
1524                                 goto no_open;
1525                         break;
1526                         /* case -EINVAL: */
1527                 default:
1528                         break;
1529                 }
1530                 goto out;
1531         }
1532 
1533         err = nfs_finish_open(ctx, ctx->dentry, file, open_flags, opened);
1534         trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
1535         put_nfs_open_context(ctx);
1536 out:
1537         if (unlikely(switched)) {
1538                 d_lookup_done(dentry);
1539                 dput(dentry);
1540         }
1541         return err;
1542 
1543 no_open:
1544         res = nfs_lookup(dir, dentry, lookup_flags);
1545         if (switched) {
1546                 d_lookup_done(dentry);
1547                 if (!res)
1548                         res = dentry;
1549                 else
1550                         dput(dentry);
1551         }
1552         if (IS_ERR(res))
1553                 return PTR_ERR(res);
1554         return finish_no_open(file, res);
1555 }
1556 EXPORT_SYMBOL_GPL(nfs_atomic_open);
1557 
1558 static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
1559 {
1560         struct inode *inode;
1561         int ret = 0;
1562 
1563         if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY))
1564                 goto no_open;
1565         if (d_mountpoint(dentry))
1566                 goto no_open;
1567         if (NFS_SB(dentry->d_sb)->caps & NFS_CAP_ATOMIC_OPEN_V1)
1568                 goto no_open;
1569 
1570         inode = d_inode(dentry);
1571 
1572         /* We can't create new files in nfs_open_revalidate(), so we
1573          * optimize away revalidation of negative dentries.
1574          */
1575         if (inode == NULL) {
1576                 struct dentry *parent;
1577                 struct inode *dir;
1578 
1579                 if (flags & LOOKUP_RCU) {
1580                         parent = READ_ONCE(dentry->d_parent);
1581                         dir = d_inode_rcu(parent);
1582                         if (!dir)
1583                                 return -ECHILD;
1584                 } else {
1585                         parent = dget_parent(dentry);
1586                         dir = d_inode(parent);
1587                 }
1588                 if (!nfs_neg_need_reval(dir, dentry, flags))
1589                         ret = 1;
1590                 else if (flags & LOOKUP_RCU)
1591                         ret = -ECHILD;
1592                 if (!(flags & LOOKUP_RCU))
1593                         dput(parent);
1594                 else if (parent != READ_ONCE(dentry->d_parent))
1595                         return -ECHILD;
1596                 goto out;
1597         }
1598 
1599         /* NFS only supports OPEN on regular files */
1600         if (!S_ISREG(inode->i_mode))
1601                 goto no_open;
1602         /* We cannot do exclusive creation on a positive dentry */
1603         if (flags & LOOKUP_EXCL)
1604                 goto no_open;
1605 
1606         /* Let f_op->open() actually open (and revalidate) the file */
1607         ret = 1;
1608 
1609 out:
1610         return ret;
1611 
1612 no_open:
1613         return nfs_lookup_revalidate(dentry, flags);
1614 }
1615 
1616 #endif /* CONFIG_NFSV4 */
1617 
1618 /*
1619  * Code common to create, mkdir, and mknod.
1620  */
1621 int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
1622                                 struct nfs_fattr *fattr,
1623                                 struct nfs4_label *label)
1624 {
1625         struct dentry *parent = dget_parent(dentry);
1626         struct inode *dir = d_inode(parent);
1627         struct inode *inode;
1628         int error = -EACCES;
1629 
1630         d_drop(dentry);
1631 
1632         /* We may have been initialized further down */
1633         if (d_really_is_positive(dentry))
1634                 goto out;
1635         if (fhandle->size == 0) {
1636                 error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, NULL);
1637                 if (error)
1638                         goto out_error;
1639         }
1640         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
1641         if (!(fattr->valid & NFS_ATTR_FATTR)) {
1642                 struct nfs_server *server = NFS_SB(dentry->d_sb);
1643                 error = server->nfs_client->rpc_ops->getattr(server, fhandle, fattr, NULL);
1644                 if (error < 0)
1645                         goto out_error;
1646         }
1647         inode = nfs_fhget(dentry->d_sb, fhandle, fattr, label);
1648         error = PTR_ERR(inode);
1649         if (IS_ERR(inode))
1650                 goto out_error;
1651         d_add(dentry, inode);
1652 out:
1653         dput(parent);
1654         return 0;
1655 out_error:
1656         nfs_mark_for_revalidate(dir);
1657         dput(parent);
1658         return error;
1659 }
1660 EXPORT_SYMBOL_GPL(nfs_instantiate);
1661 
1662 /*
1663  * Following a failed create operation, we drop the dentry rather
1664  * than retain a negative dentry. This avoids a problem in the event
1665  * that the operation succeeded on the server, but an error in the
1666  * reply path made it appear to have failed.
1667  */
1668 int nfs_create(struct inode *dir, struct dentry *dentry,
1669                 umode_t mode, bool excl)
1670 {
1671         struct iattr attr;
1672         int open_flags = excl ? O_CREAT | O_EXCL : O_CREAT;
1673         int error;
1674 
1675         dfprintk(VFS, "NFS: create(%s/%lu), %pd\n",
1676                         dir->i_sb->s_id, dir->i_ino, dentry);
1677 
1678         attr.ia_mode = mode;
1679         attr.ia_valid = ATTR_MODE;
1680 
1681         trace_nfs_create_enter(dir, dentry, open_flags);
1682         error = NFS_PROTO(dir)->create(dir, dentry, &attr, open_flags);
1683         trace_nfs_create_exit(dir, dentry, open_flags, error);
1684         if (error != 0)
1685                 goto out_err;
1686         return 0;
1687 out_err:
1688         d_drop(dentry);
1689         return error;
1690 }
1691 EXPORT_SYMBOL_GPL(nfs_create);
1692 
1693 /*
1694  * See comments for nfs_proc_create regarding failed operations.
1695  */
1696 int
1697 nfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
1698 {
1699         struct iattr attr;
1700         int status;
1701 
1702         dfprintk(VFS, "NFS: mknod(%s/%lu), %pd\n",
1703                         dir->i_sb->s_id, dir->i_ino, dentry);
1704 
1705         attr.ia_mode = mode;
1706         attr.ia_valid = ATTR_MODE;
1707 
1708         trace_nfs_mknod_enter(dir, dentry);
1709         status = NFS_PROTO(dir)->mknod(dir, dentry, &attr, rdev);
1710         trace_nfs_mknod_exit(dir, dentry, status);
1711         if (status != 0)
1712                 goto out_err;
1713         return 0;
1714 out_err:
1715         d_drop(dentry);
1716         return status;
1717 }
1718 EXPORT_SYMBOL_GPL(nfs_mknod);
1719 
1720 /*
1721  * See comments for nfs_proc_create regarding failed operations.
1722  */
1723 int nfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1724 {
1725         struct iattr attr;
1726         int error;
1727 
1728         dfprintk(VFS, "NFS: mkdir(%s/%lu), %pd\n",
1729                         dir->i_sb->s_id, dir->i_ino, dentry);
1730 
1731         attr.ia_valid = ATTR_MODE;
1732         attr.ia_mode = mode | S_IFDIR;
1733 
1734         trace_nfs_mkdir_enter(dir, dentry);
1735         error = NFS_PROTO(dir)->mkdir(dir, dentry, &attr);
1736         trace_nfs_mkdir_exit(dir, dentry, error);
1737         if (error != 0)
1738                 goto out_err;
1739         return 0;
1740 out_err:
1741         d_drop(dentry);
1742         return error;
1743 }
1744 EXPORT_SYMBOL_GPL(nfs_mkdir);
1745 
1746 static void nfs_dentry_handle_enoent(struct dentry *dentry)
1747 {
1748         if (simple_positive(dentry))
1749                 d_delete(dentry);
1750 }
1751 
1752 int nfs_rmdir(struct inode *dir, struct dentry *dentry)
1753 {
1754         int error;
1755 
1756         dfprintk(VFS, "NFS: rmdir(%s/%lu), %pd\n",
1757                         dir->i_sb->s_id, dir->i_ino, dentry);
1758 
1759         trace_nfs_rmdir_enter(dir, dentry);
1760         if (d_really_is_positive(dentry)) {
1761                 down_write(&NFS_I(d_inode(dentry))->rmdir_sem);
1762                 error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
1763                 /* Ensure the VFS deletes this inode */
1764                 switch (error) {
1765                 case 0:
1766                         clear_nlink(d_inode(dentry));
1767                         break;
1768                 case -ENOENT:
1769                         nfs_dentry_handle_enoent(dentry);
1770                 }
1771                 up_write(&NFS_I(d_inode(dentry))->rmdir_sem);
1772         } else
1773                 error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
1774         trace_nfs_rmdir_exit(dir, dentry, error);
1775 
1776         return error;
1777 }
1778 EXPORT_SYMBOL_GPL(nfs_rmdir);
1779 
1780 /*
1781  * Remove a file after making sure there are no pending writes,
1782  * and after checking that the file has only one user. 
1783  *
1784  * We invalidate the attribute cache and free the inode prior to the operation
1785  * to avoid possible races if the server reuses the inode.
1786  */
1787 static int nfs_safe_remove(struct dentry *dentry)
1788 {
1789         struct inode *dir = d_inode(dentry->d_parent);
1790         struct inode *inode = d_inode(dentry);
1791         int error = -EBUSY;
1792                 
1793         dfprintk(VFS, "NFS: safe_remove(%pd2)\n", dentry);
1794 
1795         /* If the dentry was sillyrenamed, we simply call d_delete() */
1796         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
1797                 error = 0;
1798                 goto out;
1799         }
1800 
1801         trace_nfs_remove_enter(dir, dentry);
1802         if (inode != NULL) {
1803                 error = NFS_PROTO(dir)->remove(dir, dentry);
1804                 if (error == 0)
1805                         nfs_drop_nlink(inode);
1806         } else
1807                 error = NFS_PROTO(dir)->remove(dir, dentry);
1808         if (error == -ENOENT)
1809                 nfs_dentry_handle_enoent(dentry);
1810         trace_nfs_remove_exit(dir, dentry, error);
1811 out:
1812         return error;
1813 }
1814 
1815 /*  We do silly rename. In case sillyrename() returns -EBUSY, the inode
1816  *  belongs to an active ".nfs..." file and we return -EBUSY.
1817  *
1818  *  If sillyrename() returns 0, we do nothing, otherwise we unlink.
1819  */
1820 int nfs_unlink(struct inode *dir, struct dentry *dentry)
1821 {
1822         int error;
1823         int need_rehash = 0;
1824 
1825         dfprintk(VFS, "NFS: unlink(%s/%lu, %pd)\n", dir->i_sb->s_id,
1826                 dir->i_ino, dentry);
1827 
1828         trace_nfs_unlink_enter(dir, dentry);
1829         spin_lock(&dentry->d_lock);
1830         if (d_count(dentry) > 1) {
1831                 spin_unlock(&dentry->d_lock);
1832                 /* Start asynchronous writeout of the inode */
1833                 write_inode_now(d_inode(dentry), 0);
1834                 error = nfs_sillyrename(dir, dentry);
1835                 goto out;
1836         }
1837         if (!d_unhashed(dentry)) {
1838                 __d_drop(dentry);
1839                 need_rehash = 1;
1840         }
1841         spin_unlock(&dentry->d_lock);
1842         error = nfs_safe_remove(dentry);
1843         if (!error || error == -ENOENT) {
1844                 nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
1845         } else if (need_rehash)
1846                 d_rehash(dentry);
1847 out:
1848         trace_nfs_unlink_exit(dir, dentry, error);
1849         return error;
1850 }
1851 EXPORT_SYMBOL_GPL(nfs_unlink);
1852 
1853 /*
1854  * To create a symbolic link, most file systems instantiate a new inode,
1855  * add a page to it containing the path, then write it out to the disk
1856  * using prepare_write/commit_write.
1857  *
1858  * Unfortunately the NFS client can't create the in-core inode first
1859  * because it needs a file handle to create an in-core inode (see
1860  * fs/nfs/inode.c:nfs_fhget).  We only have a file handle *after* the
1861  * symlink request has completed on the server.
1862  *
1863  * So instead we allocate a raw page, copy the symname into it, then do
1864  * the SYMLINK request with the page as the buffer.  If it succeeds, we
1865  * now have a new file handle and can instantiate an in-core NFS inode
1866  * and move the raw page into its mapping.
1867  */
1868 int nfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1869 {
1870         struct page *page;
1871         char *kaddr;
1872         struct iattr attr;
1873         unsigned int pathlen = strlen(symname);
1874         int error;
1875 
1876         dfprintk(VFS, "NFS: symlink(%s/%lu, %pd, %s)\n", dir->i_sb->s_id,
1877                 dir->i_ino, dentry, symname);
1878 
1879         if (pathlen > PAGE_SIZE)
1880                 return -ENAMETOOLONG;
1881 
1882         attr.ia_mode = S_IFLNK | S_IRWXUGO;
1883         attr.ia_valid = ATTR_MODE;
1884 
1885         page = alloc_page(GFP_USER);
1886         if (!page)
1887                 return -ENOMEM;
1888 
1889         kaddr = page_address(page);
1890         memcpy(kaddr, symname, pathlen);
1891         if (pathlen < PAGE_SIZE)
1892                 memset(kaddr + pathlen, 0, PAGE_SIZE - pathlen);
1893 
1894         trace_nfs_symlink_enter(dir, dentry);
1895         error = NFS_PROTO(dir)->symlink(dir, dentry, page, pathlen, &attr);
1896         trace_nfs_symlink_exit(dir, dentry, error);
1897         if (error != 0) {
1898                 dfprintk(VFS, "NFS: symlink(%s/%lu, %pd, %s) error %d\n",
1899                         dir->i_sb->s_id, dir->i_ino,
1900                         dentry, symname, error);
1901                 d_drop(dentry);
1902                 __free_page(page);
1903                 return error;
1904         }
1905 
1906         /*
1907          * No big deal if we can't add this page to the page cache here.
1908          * READLINK will get the missing page from the server if needed.
1909          */
1910         if (!add_to_page_cache_lru(page, d_inode(dentry)->i_mapping, 0,
1911                                                         GFP_KERNEL)) {
1912                 SetPageUptodate(page);
1913                 unlock_page(page);
1914                 /*
1915                  * add_to_page_cache_lru() grabs an extra page refcount.
1916                  * Drop it here to avoid leaking this page later.
1917                  */
1918                 put_page(page);
1919         } else
1920                 __free_page(page);
1921 
1922         return 0;
1923 }
1924 EXPORT_SYMBOL_GPL(nfs_symlink);
1925 
1926 int
1927 nfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1928 {
1929         struct inode *inode = d_inode(old_dentry);
1930         int error;
1931 
1932         dfprintk(VFS, "NFS: link(%pd2 -> %pd2)\n",
1933                 old_dentry, dentry);
1934 
1935         trace_nfs_link_enter(inode, dir, dentry);
1936         d_drop(dentry);
1937         error = NFS_PROTO(dir)->link(inode, dir, &dentry->d_name);
1938         if (error == 0) {
1939                 ihold(inode);
1940                 d_add(dentry, inode);
1941         }
1942         trace_nfs_link_exit(inode, dir, dentry, error);
1943         return error;
1944 }
1945 EXPORT_SYMBOL_GPL(nfs_link);
1946 
1947 /*
1948  * RENAME
1949  * FIXME: Some nfsds, like the Linux user space nfsd, may generate a
1950  * different file handle for the same inode after a rename (e.g. when
1951  * moving to a different directory). A fail-safe method to do so would
1952  * be to look up old_dir/old_name, create a link to new_dir/new_name and
1953  * rename the old file using the sillyrename stuff. This way, the original
1954  * file in old_dir will go away when the last process iput()s the inode.
1955  *
1956  * FIXED.
1957  * 
1958  * It actually works quite well. One needs to have the possibility for
1959  * at least one ".nfs..." file in each directory the file ever gets
1960  * moved or linked to which happens automagically with the new
1961  * implementation that only depends on the dcache stuff instead of
1962  * using the inode layer
1963  *
1964  * Unfortunately, things are a little more complicated than indicated
1965  * above. For a cross-directory move, we want to make sure we can get
1966  * rid of the old inode after the operation.  This means there must be
1967  * no pending writes (if it's a file), and the use count must be 1.
1968  * If these conditions are met, we can drop the dentries before doing
1969  * the rename.
1970  */
1971 int nfs_rename(struct inode *old_dir, struct dentry *old_dentry,
1972                struct inode *new_dir, struct dentry *new_dentry,
1973                unsigned int flags)
1974 {
1975         struct inode *old_inode = d_inode(old_dentry);
1976         struct inode *new_inode = d_inode(new_dentry);
1977         struct dentry *dentry = NULL, *rehash = NULL;
1978         struct rpc_task *task;
1979         int error = -EBUSY;
1980 
1981         if (flags)
1982                 return -EINVAL;
1983 
1984         dfprintk(VFS, "NFS: rename(%pd2 -> %pd2, ct=%d)\n",
1985                  old_dentry, new_dentry,
1986                  d_count(new_dentry));
1987 
1988         trace_nfs_rename_enter(old_dir, old_dentry, new_dir, new_dentry);
1989         /*
1990          * For non-directories, check whether the target is busy and if so,
1991          * make a copy of the dentry and then do a silly-rename. If the
1992          * silly-rename succeeds, the copied dentry is hashed and becomes
1993          * the new target.
1994          */
1995         if (new_inode && !S_ISDIR(new_inode->i_mode)) {
1996                 /*
1997                  * To prevent any new references to the target during the
1998                  * rename, we unhash the dentry in advance.
1999                  */
2000                 if (!d_unhashed(new_dentry)) {
2001                         d_drop(new_dentry);
2002                         rehash = new_dentry;
2003                 }
2004 
2005                 if (d_count(new_dentry) > 2) {
2006                         int err;
2007 
2008                         /* copy the target dentry's name */
2009                         dentry = d_alloc(new_dentry->d_parent,
2010                                          &new_dentry->d_name);
2011                         if (!dentry)
2012                                 goto out;
2013 
2014                         /* silly-rename the existing target ... */
2015                         err = nfs_sillyrename(new_dir, new_dentry);
2016                         if (err)
2017                                 goto out;
2018 
2019                         new_dentry = dentry;
2020                         rehash = NULL;
2021                         new_inode = NULL;
2022                 }
2023         }
2024 
2025         task = nfs_async_rename(old_dir, new_dir, old_dentry, new_dentry, NULL);
2026         if (IS_ERR(task)) {
2027                 error = PTR_ERR(task);
2028                 goto out;
2029         }
2030 
2031         error = rpc_wait_for_completion_task(task);
2032         if (error != 0) {
2033                 ((struct nfs_renamedata *)task->tk_calldata)->cancelled = 1;
2034                 /* Paired with the atomic_dec_and_test() barrier in rpc_do_put_task() */
2035                 smp_wmb();
2036         } else
2037                 error = task->tk_status;
2038         rpc_put_task(task);
2039         nfs_mark_for_revalidate(old_inode);
2040 out:
2041         if (rehash)
2042                 d_rehash(rehash);
2043         trace_nfs_rename_exit(old_dir, old_dentry,
2044                         new_dir, new_dentry, error);
2045         if (!error) {
2046                 if (new_inode != NULL)
2047                         nfs_drop_nlink(new_inode);
2048                 /*
2049                  * The d_move() should be here instead of in an async RPC completion
2050                  * handler because we need the proper locks to move the dentry.  If
2051                  * we're interrupted by a signal, the async RPC completion handler
2052                  * should mark the directories for revalidation.
2053                  */
2054                 d_move(old_dentry, new_dentry);
2055                 nfs_set_verifier(old_dentry,
2056                                         nfs_save_change_attribute(new_dir));
2057         } else if (error == -ENOENT)
2058                 nfs_dentry_handle_enoent(old_dentry);
2059 
2060         /* new dentry created? */
2061         if (dentry)
2062                 dput(dentry);
2063         return error;
2064 }
2065 EXPORT_SYMBOL_GPL(nfs_rename);
2066 
2067 static DEFINE_SPINLOCK(nfs_access_lru_lock);
2068 static LIST_HEAD(nfs_access_lru_list);
2069 static atomic_long_t nfs_access_nr_entries;
2070 
2071 static unsigned long nfs_access_max_cachesize = ULONG_MAX;
2072 module_param(nfs_access_max_cachesize, ulong, 0644);
2073 MODULE_PARM_DESC(nfs_access_max_cachesize, "NFS access maximum total cache length");
2074 
2075 static void nfs_access_free_entry(struct nfs_access_entry *entry)
2076 {
2077         put_rpccred(entry->cred);
2078         kfree_rcu(entry, rcu_head);
2079         smp_mb__before_atomic();
2080         atomic_long_dec(&nfs_access_nr_entries);
2081         smp_mb__after_atomic();
2082 }
2083 
2084 static void nfs_access_free_list(struct list_head *head)
2085 {
2086         struct nfs_access_entry *cache;
2087 
2088         while (!list_empty(head)) {
2089                 cache = list_entry(head->next, struct nfs_access_entry, lru);
2090                 list_del(&cache->lru);
2091                 nfs_access_free_entry(cache);
2092         }
2093 }
2094 
2095 static unsigned long
2096 nfs_do_access_cache_scan(unsigned int nr_to_scan)
2097 {
2098         LIST_HEAD(head);
2099         struct nfs_inode *nfsi, *next;
2100         struct nfs_access_entry *cache;
2101         long freed = 0;
2102 
2103         spin_lock(&nfs_access_lru_lock);
2104         list_for_each_entry_safe(nfsi, next, &nfs_access_lru_list, access_cache_inode_lru) {
2105                 struct inode *inode;
2106 
2107                 if (nr_to_scan-- == 0)
2108                         break;
2109                 inode = &nfsi->vfs_inode;
2110                 spin_lock(&inode->i_lock);
2111                 if (list_empty(&nfsi->access_cache_entry_lru))
2112                         goto remove_lru_entry;
2113                 cache = list_entry(nfsi->access_cache_entry_lru.next,
2114                                 struct nfs_access_entry, lru);
2115                 list_move(&cache->lru, &head);
2116                 rb_erase(&cache->rb_node, &nfsi->access_cache);
2117                 freed++;
2118                 if (!list_empty(&nfsi->access_cache_entry_lru))
2119                         list_move_tail(&nfsi->access_cache_inode_lru,
2120                                         &nfs_access_lru_list);
2121                 else {
2122 remove_lru_entry:
2123                         list_del_init(&nfsi->access_cache_inode_lru);
2124                         smp_mb__before_atomic();
2125                         clear_bit(NFS_INO_ACL_LRU_SET, &nfsi->flags);
2126                         smp_mb__after_atomic();
2127                 }
2128                 spin_unlock(&inode->i_lock);
2129         }
2130         spin_unlock(&nfs_access_lru_lock);
2131         nfs_access_free_list(&head);
2132         return freed;
2133 }
2134 
2135 unsigned long
2136 nfs_access_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
2137 {
2138         int nr_to_scan = sc->nr_to_scan;
2139         gfp_t gfp_mask = sc->gfp_mask;
2140 
2141         if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
2142                 return SHRINK_STOP;
2143         return nfs_do_access_cache_scan(nr_to_scan);
2144 }
2145 
2146 
2147 unsigned long
2148 nfs_access_cache_count(struct shrinker *shrink, struct shrink_control *sc)
2149 {
2150         return vfs_pressure_ratio(atomic_long_read(&nfs_access_nr_entries));
2151 }
2152 
2153 static void
2154 nfs_access_cache_enforce_limit(void)
2155 {
2156         long nr_entries = atomic_long_read(&nfs_access_nr_entries);
2157         unsigned long diff;
2158         unsigned int nr_to_scan;
2159 
2160         if (nr_entries < 0 || nr_entries <= nfs_access_max_cachesize)
2161                 return;
2162         nr_to_scan = 100;
2163         diff = nr_entries - nfs_access_max_cachesize;
2164         if (diff < nr_to_scan)
2165                 nr_to_scan = diff;
2166         nfs_do_access_cache_scan(nr_to_scan);
2167 }
2168 
2169 static void __nfs_access_zap_cache(struct nfs_inode *nfsi, struct list_head *head)
2170 {
2171         struct rb_root *root_node = &nfsi->access_cache;
2172         struct rb_node *n;
2173         struct nfs_access_entry *entry;
2174 
2175         /* Unhook entries from the cache */
2176         while ((n = rb_first(root_node)) != NULL) {
2177                 entry = rb_entry(n, struct nfs_access_entry, rb_node);
2178                 rb_erase(n, root_node);
2179                 list_move(&entry->lru, head);
2180         }
2181         nfsi->cache_validity &= ~NFS_INO_INVALID_ACCESS;
2182 }
2183 
2184 void nfs_access_zap_cache(struct inode *inode)
2185 {
2186         LIST_HEAD(head);
2187 
2188         if (test_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags) == 0)
2189                 return;
2190         /* Remove from global LRU init */
2191         spin_lock(&nfs_access_lru_lock);
2192         if (test_and_clear_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags))
2193                 list_del_init(&NFS_I(inode)->access_cache_inode_lru);
2194 
2195         spin_lock(&inode->i_lock);
2196         __nfs_access_zap_cache(NFS_I(inode), &head);
2197         spin_unlock(&inode->i_lock);
2198         spin_unlock(&nfs_access_lru_lock);
2199         nfs_access_free_list(&head);
2200 }
2201 EXPORT_SYMBOL_GPL(nfs_access_zap_cache);
2202 
2203 static struct nfs_access_entry *nfs_access_search_rbtree(struct inode *inode, struct rpc_cred *cred)
2204 {
2205         struct rb_node *n = NFS_I(inode)->access_cache.rb_node;
2206         struct nfs_access_entry *entry;
2207 
2208         while (n != NULL) {
2209                 entry = rb_entry(n, struct nfs_access_entry, rb_node);
2210 
2211                 if (cred < entry->cred)
2212                         n = n->rb_left;
2213                 else if (cred > entry->cred)
2214                         n = n->rb_right;
2215                 else
2216                         return entry;
2217         }
2218         return NULL;
2219 }
2220 
2221 static int nfs_access_get_cached(struct inode *inode, struct rpc_cred *cred, struct nfs_access_entry *res, bool may_block)
2222 {
2223         struct nfs_inode *nfsi = NFS_I(inode);
2224         struct nfs_access_entry *cache;
2225         bool retry = true;
2226         int err;
2227 
2228         spin_lock(&inode->i_lock);
2229         for(;;) {
2230                 if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
2231                         goto out_zap;
2232                 cache = nfs_access_search_rbtree(inode, cred);
2233                 err = -ENOENT;
2234                 if (cache == NULL)
2235                         goto out;
2236                 /* Found an entry, is our attribute cache valid? */
2237                 if (!nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS))
2238                         break;
2239                 err = -ECHILD;
2240                 if (!may_block)
2241                         goto out;
2242                 if (!retry)
2243                         goto out_zap;
2244                 spin_unlock(&inode->i_lock);
2245                 err = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
2246                 if (err)
2247                         return err;
2248                 spin_lock(&inode->i_lock);
2249                 retry = false;
2250         }
2251         res->cred = cache->cred;
2252         res->mask = cache->mask;
2253         list_move_tail(&cache->lru, &nfsi->access_cache_entry_lru);
2254         err = 0;
2255 out:
2256         spin_unlock(&inode->i_lock);
2257         return err;
2258 out_zap:
2259         spin_unlock(&inode->i_lock);
2260         nfs_access_zap_cache(inode);
2261         return -ENOENT;
2262 }
2263 
2264 static int nfs_access_get_cached_rcu(struct inode *inode, struct rpc_cred *cred, struct nfs_access_entry *res)
2265 {
2266         /* Only check the most recently returned cache entry,
2267          * but do it without locking.
2268          */
2269         struct nfs_inode *nfsi = NFS_I(inode);
2270         struct nfs_access_entry *cache;
2271         int err = -ECHILD;
2272         struct list_head *lh;
2273 
2274         rcu_read_lock();
2275         if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
2276                 goto out;
2277         lh = rcu_dereference(nfsi->access_cache_entry_lru.prev);
2278         cache = list_entry(lh, struct nfs_access_entry, lru);
2279         if (lh == &nfsi->access_cache_entry_lru ||
2280             cred != cache->cred)
2281                 cache = NULL;
2282         if (cache == NULL)
2283                 goto out;
2284         if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS))
2285                 goto out;
2286         res->cred = cache->cred;
2287         res->mask = cache->mask;
2288         err = 0;
2289 out:
2290         rcu_read_unlock();
2291         return err;
2292 }
2293 
2294 static void nfs_access_add_rbtree(struct inode *inode, struct nfs_access_entry *set)
2295 {
2296         struct nfs_inode *nfsi = NFS_I(inode);
2297         struct rb_root *root_node = &nfsi->access_cache;
2298         struct rb_node **p = &root_node->rb_node;
2299         struct rb_node *parent = NULL;
2300         struct nfs_access_entry *entry;
2301 
2302         spin_lock(&inode->i_lock);
2303         while (*p != NULL) {
2304                 parent = *p;
2305                 entry = rb_entry(parent, struct nfs_access_entry, rb_node);
2306 
2307                 if (set->cred < entry->cred)
2308                         p = &parent->rb_left;
2309                 else if (set->cred > entry->cred)
2310                         p = &parent->rb_right;
2311                 else
2312                         goto found;
2313         }
2314         rb_link_node(&set->rb_node, parent, p);
2315         rb_insert_color(&set->rb_node, root_node);
2316         list_add_tail(&set->lru, &nfsi->access_cache_entry_lru);
2317         spin_unlock(&inode->i_lock);
2318         return;
2319 found:
2320         rb_replace_node(parent, &set->rb_node, root_node);
2321         list_add_tail(&set->lru, &nfsi->access_cache_entry_lru);
2322         list_del(&entry->lru);
2323         spin_unlock(&inode->i_lock);
2324         nfs_access_free_entry(entry);
2325 }
2326 
2327 void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set)
2328 {
2329         struct nfs_access_entry *cache = kmalloc(sizeof(*cache), GFP_KERNEL);
2330         if (cache == NULL)
2331                 return;
2332         RB_CLEAR_NODE(&cache->rb_node);
2333         cache->cred = get_rpccred(set->cred);
2334         cache->mask = set->mask;
2335 
2336         /* The above field assignments must be visible
2337          * before this item appears on the lru.  We cannot easily
2338          * use rcu_assign_pointer, so just force the memory barrier.
2339          */
2340         smp_wmb();
2341         nfs_access_add_rbtree(inode, cache);
2342 
2343         /* Update accounting */
2344         smp_mb__before_atomic();
2345         atomic_long_inc(&nfs_access_nr_entries);
2346         smp_mb__after_atomic();
2347 
2348         /* Add inode to global LRU list */
2349         if (!test_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags)) {
2350                 spin_lock(&nfs_access_lru_lock);
2351                 if (!test_and_set_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags))
2352                         list_add_tail(&NFS_I(inode)->access_cache_inode_lru,
2353                                         &nfs_access_lru_list);
2354                 spin_unlock(&nfs_access_lru_lock);
2355         }
2356         nfs_access_cache_enforce_limit();
2357 }
2358 EXPORT_SYMBOL_GPL(nfs_access_add_cache);
2359 
2360 #define NFS_MAY_READ (NFS_ACCESS_READ)
2361 #define NFS_MAY_WRITE (NFS_ACCESS_MODIFY | \
2362                 NFS_ACCESS_EXTEND | \
2363                 NFS_ACCESS_DELETE)
2364 #define NFS_FILE_MAY_WRITE (NFS_ACCESS_MODIFY | \
2365                 NFS_ACCESS_EXTEND)
2366 #define NFS_DIR_MAY_WRITE NFS_MAY_WRITE
2367 #define NFS_MAY_LOOKUP (NFS_ACCESS_LOOKUP)
2368 #define NFS_MAY_EXECUTE (NFS_ACCESS_EXECUTE)
2369 static int
2370 nfs_access_calc_mask(u32 access_result, umode_t umode)
2371 {
2372         int mask = 0;
2373 
2374         if (access_result & NFS_MAY_READ)
2375                 mask |= MAY_READ;
2376         if (S_ISDIR(umode)) {
2377                 if ((access_result & NFS_DIR_MAY_WRITE) == NFS_DIR_MAY_WRITE)
2378                         mask |= MAY_WRITE;
2379                 if ((access_result & NFS_MAY_LOOKUP) == NFS_MAY_LOOKUP)
2380                         mask |= MAY_EXEC;
2381         } else if (S_ISREG(umode)) {
2382                 if ((access_result & NFS_FILE_MAY_WRITE) == NFS_FILE_MAY_WRITE)
2383                         mask |= MAY_WRITE;
2384                 if ((access_result & NFS_MAY_EXECUTE) == NFS_MAY_EXECUTE)
2385                         mask |= MAY_EXEC;
2386         } else if (access_result & NFS_MAY_WRITE)
2387                         mask |= MAY_WRITE;
2388         return mask;
2389 }
2390 
2391 void nfs_access_set_mask(struct nfs_access_entry *entry, u32 access_result)
2392 {
2393         entry->mask = access_result;
2394 }
2395 EXPORT_SYMBOL_GPL(nfs_access_set_mask);
2396 
2397 static int nfs_do_access(struct inode *inode, struct rpc_cred *cred, int mask)
2398 {
2399         struct nfs_access_entry cache;
2400         bool may_block = (mask & MAY_NOT_BLOCK) == 0;
2401         int cache_mask;
2402         int status;
2403 
2404         trace_nfs_access_enter(inode);
2405 
2406         status = nfs_access_get_cached_rcu(inode, cred, &cache);
2407         if (status != 0)
2408                 status = nfs_access_get_cached(inode, cred, &cache, may_block);
2409         if (status == 0)
2410                 goto out_cached;
2411 
2412         status = -ECHILD;
2413         if (!may_block)
2414                 goto out;
2415 
2416         /*
2417          * Determine which access bits we want to ask for...
2418          */
2419         cache.mask = NFS_ACCESS_READ | NFS_ACCESS_MODIFY | NFS_ACCESS_EXTEND;
2420         if (S_ISDIR(inode->i_mode))
2421                 cache.mask |= NFS_ACCESS_DELETE | NFS_ACCESS_LOOKUP;
2422         else
2423                 cache.mask |= NFS_ACCESS_EXECUTE;
2424         cache.cred = cred;
2425         status = NFS_PROTO(inode)->access(inode, &cache);
2426         if (status != 0) {
2427                 if (status == -ESTALE) {
2428                         nfs_zap_caches(inode);
2429                         if (!S_ISDIR(inode->i_mode))
2430                                 set_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
2431                 }
2432                 goto out;
2433         }
2434         nfs_access_add_cache(inode, &cache);
2435 out_cached:
2436         cache_mask = nfs_access_calc_mask(cache.mask, inode->i_mode);
2437         if ((mask & ~cache_mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) != 0)
2438                 status = -EACCES;
2439 out:
2440         trace_nfs_access_exit(inode, status);
2441         return status;
2442 }
2443 
2444 static int nfs_open_permission_mask(int openflags)
2445 {
2446         int mask = 0;
2447 
2448         if (openflags & __FMODE_EXEC) {
2449                 /* ONLY check exec rights */
2450                 mask = MAY_EXEC;
2451         } else {
2452                 if ((openflags & O_ACCMODE) != O_WRONLY)
2453                         mask |= MAY_READ;
2454                 if ((openflags & O_ACCMODE) != O_RDONLY)
2455                         mask |= MAY_WRITE;
2456         }
2457 
2458         return mask;
2459 }
2460 
2461 int nfs_may_open(struct inode *inode, struct rpc_cred *cred, int openflags)
2462 {
2463         return nfs_do_access(inode, cred, nfs_open_permission_mask(openflags));
2464 }
2465 EXPORT_SYMBOL_GPL(nfs_may_open);
2466 
2467 static int nfs_execute_ok(struct inode *inode, int mask)
2468 {
2469         struct nfs_server *server = NFS_SERVER(inode);
2470         int ret = 0;
2471 
2472         if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS)) {
2473                 if (mask & MAY_NOT_BLOCK)
2474                         return -ECHILD;
2475                 ret = __nfs_revalidate_inode(server, inode);
2476         }
2477         if (ret == 0 && !execute_ok(inode))
2478                 ret = -EACCES;
2479         return ret;
2480 }
2481 
2482 int nfs_permission(struct inode *inode, int mask)
2483 {
2484         struct rpc_cred *cred;
2485         int res = 0;
2486 
2487         nfs_inc_stats(inode, NFSIOS_VFSACCESS);
2488 
2489         if ((mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
2490                 goto out;
2491         /* Is this sys_access() ? */
2492         if (mask & (MAY_ACCESS | MAY_CHDIR))
2493                 goto force_lookup;
2494 
2495         switch (inode->i_mode & S_IFMT) {
2496                 case S_IFLNK:
2497                         goto out;
2498                 case S_IFREG:
2499                         if ((mask & MAY_OPEN) &&
2500                            nfs_server_capable(inode, NFS_CAP_ATOMIC_OPEN))
2501                                 return 0;
2502                         break;
2503                 case S_IFDIR:
2504                         /*
2505                          * Optimize away all write operations, since the server
2506                          * will check permissions when we perform the op.
2507                          */
2508                         if ((mask & MAY_WRITE) && !(mask & MAY_READ))
2509                                 goto out;
2510         }
2511 
2512 force_lookup:
2513         if (!NFS_PROTO(inode)->access)
2514                 goto out_notsup;
2515 
2516         /* Always try fast lookups first */
2517         rcu_read_lock();
2518         cred = rpc_lookup_cred_nonblock();
2519         if (!IS_ERR(cred))
2520                 res = nfs_do_access(inode, cred, mask|MAY_NOT_BLOCK);
2521         else
2522                 res = PTR_ERR(cred);
2523         rcu_read_unlock();
2524         if (res == -ECHILD && !(mask & MAY_NOT_BLOCK)) {
2525                 /* Fast lookup failed, try the slow way */
2526                 cred = rpc_lookup_cred();
2527                 if (!IS_ERR(cred)) {
2528                         res = nfs_do_access(inode, cred, mask);
2529                         put_rpccred(cred);
2530                 } else
2531                         res = PTR_ERR(cred);
2532         }
2533 out:
2534         if (!res && (mask & MAY_EXEC))
2535                 res = nfs_execute_ok(inode, mask);
2536 
2537         dfprintk(VFS, "NFS: permission(%s/%lu), mask=0x%x, res=%d\n",
2538                 inode->i_sb->s_id, inode->i_ino, mask, res);
2539         return res;
2540 out_notsup:
2541         if (mask & MAY_NOT_BLOCK)
2542                 return -ECHILD;
2543 
2544         res = nfs_revalidate_inode(NFS_SERVER(inode), inode);
2545         if (res == 0)
2546                 res = generic_permission(inode, mask);
2547         goto out;
2548 }
2549 EXPORT_SYMBOL_GPL(nfs_permission);
2550 
2551 /*
2552  * Local variables:
2553  *  version-control: t
2554  *  kept-new-versions: 5
2555  * End:
2556  */
2557 

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