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TOMOYO Linux Cross Reference
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_shared = 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         if (filp->f_path.dentry == filp->f_path.mnt->mnt_root) {
122                 /* This is a mountpoint, so d_revalidate will never
123                  * have been called, so we need to refresh the
124                  * inode (for close-open consistency) ourselves.
125                  */
126                 __nfs_revalidate_inode(NFS_SERVER(inode), inode);
127         }
128 out:
129         put_rpccred(cred);
130         return res;
131 }
132 
133 static int
134 nfs_closedir(struct inode *inode, struct file *filp)
135 {
136         put_nfs_open_dir_context(file_inode(filp), filp->private_data);
137         return 0;
138 }
139 
140 struct nfs_cache_array_entry {
141         u64 cookie;
142         u64 ino;
143         struct qstr string;
144         unsigned char d_type;
145 };
146 
147 struct nfs_cache_array {
148         atomic_t refcount;
149         int size;
150         int eof_index;
151         u64 last_cookie;
152         struct nfs_cache_array_entry array[0];
153 };
154 
155 typedef int (*decode_dirent_t)(struct xdr_stream *, struct nfs_entry *, int);
156 typedef struct {
157         struct file     *file;
158         struct page     *page;
159         struct dir_context *ctx;
160         unsigned long   page_index;
161         u64             *dir_cookie;
162         u64             last_cookie;
163         loff_t          current_index;
164         decode_dirent_t decode;
165 
166         unsigned long   timestamp;
167         unsigned long   gencount;
168         unsigned int    cache_entry_index;
169         unsigned int    plus:1;
170         unsigned int    eof:1;
171 } nfs_readdir_descriptor_t;
172 
173 /*
174  * The caller is responsible for calling nfs_readdir_release_array(page)
175  */
176 static
177 struct nfs_cache_array *nfs_readdir_get_array(struct page *page)
178 {
179         void *ptr;
180         if (page == NULL)
181                 return ERR_PTR(-EIO);
182         ptr = kmap(page);
183         if (ptr == NULL)
184                 return ERR_PTR(-ENOMEM);
185         return ptr;
186 }
187 
188 static
189 void nfs_readdir_release_array(struct page *page)
190 {
191         kunmap(page);
192 }
193 
194 /*
195  * we are freeing strings created by nfs_add_to_readdir_array()
196  */
197 static
198 void nfs_readdir_clear_array(struct page *page)
199 {
200         struct nfs_cache_array *array;
201         int i;
202 
203         array = kmap_atomic(page);
204         if (atomic_dec_and_test(&array->refcount))
205                 for (i = 0; i < array->size; i++)
206                         kfree(array->array[i].string.name);
207         kunmap_atomic(array);
208 }
209 
210 static bool grab_page(struct page *page)
211 {
212         struct nfs_cache_array *array = kmap_atomic(page);
213         bool res = atomic_inc_not_zero(&array->refcount);
214         kunmap_atomic(array);
215         return res;
216 }
217 
218 /*
219  * the caller is responsible for freeing qstr.name
220  * when called by nfs_readdir_add_to_array, the strings will be freed in
221  * nfs_clear_readdir_array()
222  */
223 static
224 int nfs_readdir_make_qstr(struct qstr *string, const char *name, unsigned int len)
225 {
226         string->len = len;
227         string->name = kmemdup(name, len, GFP_KERNEL);
228         if (string->name == NULL)
229                 return -ENOMEM;
230         /*
231          * Avoid a kmemleak false positive. The pointer to the name is stored
232          * in a page cache page which kmemleak does not scan.
233          */
234         kmemleak_not_leak(string->name);
235         string->hash = full_name_hash(NULL, name, len);
236         return 0;
237 }
238 
239 static
240 int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
241 {
242         struct nfs_cache_array *array = nfs_readdir_get_array(page);
243         struct nfs_cache_array_entry *cache_entry;
244         int ret;
245 
246         if (IS_ERR(array))
247                 return PTR_ERR(array);
248 
249         cache_entry = &array->array[array->size];
250 
251         /* Check that this entry lies within the page bounds */
252         ret = -ENOSPC;
253         if ((char *)&cache_entry[1] - (char *)page_address(page) > PAGE_SIZE)
254                 goto out;
255 
256         cache_entry->cookie = entry->prev_cookie;
257         cache_entry->ino = entry->ino;
258         cache_entry->d_type = entry->d_type;
259         ret = nfs_readdir_make_qstr(&cache_entry->string, entry->name, entry->len);
260         if (ret)
261                 goto out;
262         array->last_cookie = entry->cookie;
263         array->size++;
264         if (entry->eof != 0)
265                 array->eof_index = array->size;
266 out:
267         nfs_readdir_release_array(page);
268         return ret;
269 }
270 
271 static
272 int nfs_readdir_search_for_pos(struct nfs_cache_array *array, nfs_readdir_descriptor_t *desc)
273 {
274         loff_t diff = desc->ctx->pos - desc->current_index;
275         unsigned int index;
276 
277         if (diff < 0)
278                 goto out_eof;
279         if (diff >= array->size) {
280                 if (array->eof_index >= 0)
281                         goto out_eof;
282                 return -EAGAIN;
283         }
284 
285         index = (unsigned int)diff;
286         *desc->dir_cookie = array->array[index].cookie;
287         desc->cache_entry_index = index;
288         return 0;
289 out_eof:
290         desc->eof = 1;
291         return -EBADCOOKIE;
292 }
293 
294 static bool
295 nfs_readdir_inode_mapping_valid(struct nfs_inode *nfsi)
296 {
297         if (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))
298                 return false;
299         smp_rmb();
300         return !test_bit(NFS_INO_INVALIDATING, &nfsi->flags);
301 }
302 
303 static
304 int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_descriptor_t *desc)
305 {
306         int i;
307         loff_t new_pos;
308         int status = -EAGAIN;
309 
310         for (i = 0; i < array->size; i++) {
311                 if (array->array[i].cookie == *desc->dir_cookie) {
312                         struct nfs_inode *nfsi = NFS_I(file_inode(desc->file));
313                         struct nfs_open_dir_context *ctx = desc->file->private_data;
314 
315                         new_pos = desc->current_index + i;
316                         if (ctx->attr_gencount != nfsi->attr_gencount ||
317                             !nfs_readdir_inode_mapping_valid(nfsi)) {
318                                 ctx->duped = 0;
319                                 ctx->attr_gencount = nfsi->attr_gencount;
320                         } else if (new_pos < desc->ctx->pos) {
321                                 if (ctx->duped > 0
322                                     && ctx->dup_cookie == *desc->dir_cookie) {
323                                         if (printk_ratelimit()) {
324                                                 pr_notice("NFS: directory %pD2 contains a readdir loop."
325                                                                 "Please contact your server vendor.  "
326                                                                 "The file: %.*s has duplicate cookie %llu\n",
327                                                                 desc->file, array->array[i].string.len,
328                                                                 array->array[i].string.name, *desc->dir_cookie);
329                                         }
330                                         status = -ELOOP;
331                                         goto out;
332                                 }
333                                 ctx->dup_cookie = *desc->dir_cookie;
334                                 ctx->duped = -1;
335                         }
336                         desc->ctx->pos = new_pos;
337                         desc->cache_entry_index = i;
338                         return 0;
339                 }
340         }
341         if (array->eof_index >= 0) {
342                 status = -EBADCOOKIE;
343                 if (*desc->dir_cookie == array->last_cookie)
344                         desc->eof = 1;
345         }
346 out:
347         return status;
348 }
349 
350 static
351 int nfs_readdir_search_array(nfs_readdir_descriptor_t *desc)
352 {
353         struct nfs_cache_array *array;
354         int status;
355 
356         array = nfs_readdir_get_array(desc->page);
357         if (IS_ERR(array)) {
358                 status = PTR_ERR(array);
359                 goto out;
360         }
361 
362         if (*desc->dir_cookie == 0)
363                 status = nfs_readdir_search_for_pos(array, desc);
364         else
365                 status = nfs_readdir_search_for_cookie(array, desc);
366 
367         if (status == -EAGAIN) {
368                 desc->last_cookie = array->last_cookie;
369                 desc->current_index += array->size;
370                 desc->page_index++;
371         }
372         nfs_readdir_release_array(desc->page);
373 out:
374         return status;
375 }
376 
377 /* Fill a page with xdr information before transferring to the cache page */
378 static
379 int nfs_readdir_xdr_filler(struct page **pages, nfs_readdir_descriptor_t *desc,
380                         struct nfs_entry *entry, struct file *file, struct inode *inode)
381 {
382         struct nfs_open_dir_context *ctx = file->private_data;
383         struct rpc_cred *cred = ctx->cred;
384         unsigned long   timestamp, gencount;
385         int             error;
386 
387  again:
388         timestamp = jiffies;
389         gencount = nfs_inc_attr_generation_counter();
390         error = NFS_PROTO(inode)->readdir(file_dentry(file), cred, entry->cookie, pages,
391                                           NFS_SERVER(inode)->dtsize, desc->plus);
392         if (error < 0) {
393                 /* We requested READDIRPLUS, but the server doesn't grok it */
394                 if (error == -ENOTSUPP && desc->plus) {
395                         NFS_SERVER(inode)->caps &= ~NFS_CAP_READDIRPLUS;
396                         clear_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(inode)->flags);
397                         desc->plus = 0;
398                         goto again;
399                 }
400                 goto error;
401         }
402         desc->timestamp = timestamp;
403         desc->gencount = gencount;
404 error:
405         return error;
406 }
407 
408 static int xdr_decode(nfs_readdir_descriptor_t *desc,
409                       struct nfs_entry *entry, struct xdr_stream *xdr)
410 {
411         int error;
412 
413         error = desc->decode(xdr, entry, desc->plus);
414         if (error)
415                 return error;
416         entry->fattr->time_start = desc->timestamp;
417         entry->fattr->gencount = desc->gencount;
418         return 0;
419 }
420 
421 /* Match file and dirent using either filehandle or fileid
422  * Note: caller is responsible for checking the fsid
423  */
424 static
425 int nfs_same_file(struct dentry *dentry, struct nfs_entry *entry)
426 {
427         struct inode *inode;
428         struct nfs_inode *nfsi;
429 
430         if (d_really_is_negative(dentry))
431                 return 0;
432 
433         inode = d_inode(dentry);
434         if (is_bad_inode(inode) || NFS_STALE(inode))
435                 return 0;
436 
437         nfsi = NFS_I(inode);
438         if (entry->fattr->fileid != nfsi->fileid)
439                 return 0;
440         if (entry->fh->size && nfs_compare_fh(entry->fh, &nfsi->fh) != 0)
441                 return 0;
442         return 1;
443 }
444 
445 static
446 bool nfs_use_readdirplus(struct inode *dir, struct dir_context *ctx)
447 {
448         if (!nfs_server_capable(dir, NFS_CAP_READDIRPLUS))
449                 return false;
450         if (test_and_clear_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(dir)->flags))
451                 return true;
452         if (ctx->pos == 0)
453                 return true;
454         return false;
455 }
456 
457 /*
458  * This function is called by the lookup and getattr code to request the
459  * use of readdirplus to accelerate any future lookups in the same
460  * directory.
461  */
462 void nfs_advise_use_readdirplus(struct inode *dir)
463 {
464         struct nfs_inode *nfsi = NFS_I(dir);
465 
466         if (nfs_server_capable(dir, NFS_CAP_READDIRPLUS) &&
467             !list_empty(&nfsi->open_files))
468                 set_bit(NFS_INO_ADVISE_RDPLUS, &nfsi->flags);
469 }
470 
471 /*
472  * This function is mainly for use by nfs_getattr().
473  *
474  * If this is an 'ls -l', we want to force use of readdirplus.
475  * Do this by checking if there is an active file descriptor
476  * and calling nfs_advise_use_readdirplus, then forcing a
477  * cache flush.
478  */
479 void nfs_force_use_readdirplus(struct inode *dir)
480 {
481         struct nfs_inode *nfsi = NFS_I(dir);
482 
483         if (nfs_server_capable(dir, NFS_CAP_READDIRPLUS) &&
484             !list_empty(&nfsi->open_files)) {
485                 set_bit(NFS_INO_ADVISE_RDPLUS, &nfsi->flags);
486                 invalidate_mapping_pages(dir->i_mapping, 0, -1);
487         }
488 }
489 
490 static
491 void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry)
492 {
493         struct qstr filename = QSTR_INIT(entry->name, entry->len);
494         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
495         struct dentry *dentry;
496         struct dentry *alias;
497         struct inode *dir = d_inode(parent);
498         struct inode *inode;
499         int status;
500 
501         if (!(entry->fattr->valid & NFS_ATTR_FATTR_FILEID))
502                 return;
503         if (!(entry->fattr->valid & NFS_ATTR_FATTR_FSID))
504                 return;
505         if (filename.len == 0)
506                 return;
507         /* Validate that the name doesn't contain any illegal '\0' */
508         if (strnlen(filename.name, filename.len) != filename.len)
509                 return;
510         /* ...or '/' */
511         if (strnchr(filename.name, filename.len, '/'))
512                 return;
513         if (filename.name[0] == '.') {
514                 if (filename.len == 1)
515                         return;
516                 if (filename.len == 2 && filename.name[1] == '.')
517                         return;
518         }
519         filename.hash = full_name_hash(parent, filename.name, filename.len);
520 
521         dentry = d_lookup(parent, &filename);
522 again:
523         if (!dentry) {
524                 dentry = d_alloc_parallel(parent, &filename, &wq);
525                 if (IS_ERR(dentry))
526                         return;
527         }
528         if (!d_in_lookup(dentry)) {
529                 /* Is there a mountpoint here? If so, just exit */
530                 if (!nfs_fsid_equal(&NFS_SB(dentry->d_sb)->fsid,
531                                         &entry->fattr->fsid))
532                         goto out;
533                 if (nfs_same_file(dentry, entry)) {
534                         if (!entry->fh->size)
535                                 goto out;
536                         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
537                         status = nfs_refresh_inode(d_inode(dentry), entry->fattr);
538                         if (!status)
539                                 nfs_setsecurity(d_inode(dentry), entry->fattr, entry->label);
540                         goto out;
541                 } else {
542                         d_invalidate(dentry);
543                         dput(dentry);
544                         dentry = NULL;
545                         goto again;
546                 }
547         }
548         if (!entry->fh->size) {
549                 d_lookup_done(dentry);
550                 goto out;
551         }
552 
553         inode = nfs_fhget(dentry->d_sb, entry->fh, entry->fattr, entry->label);
554         alias = d_splice_alias(inode, dentry);
555         d_lookup_done(dentry);
556         if (alias) {
557                 if (IS_ERR(alias))
558                         goto out;
559                 dput(dentry);
560                 dentry = alias;
561         }
562         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
563 out:
564         dput(dentry);
565 }
566 
567 /* Perform conversion from xdr to cache array */
568 static
569 int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *entry,
570                                 struct page **xdr_pages, struct page *page, unsigned int buflen)
571 {
572         struct xdr_stream stream;
573         struct xdr_buf buf;
574         struct page *scratch;
575         struct nfs_cache_array *array;
576         unsigned int count = 0;
577         int status;
578 
579         scratch = alloc_page(GFP_KERNEL);
580         if (scratch == NULL)
581                 return -ENOMEM;
582 
583         if (buflen == 0)
584                 goto out_nopages;
585 
586         xdr_init_decode_pages(&stream, &buf, xdr_pages, buflen);
587         xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);
588 
589         do {
590                 status = xdr_decode(desc, entry, &stream);
591                 if (status != 0) {
592                         if (status == -EAGAIN)
593                                 status = 0;
594                         break;
595                 }
596 
597                 count++;
598 
599                 if (desc->plus != 0)
600                         nfs_prime_dcache(file_dentry(desc->file), entry);
601 
602                 status = nfs_readdir_add_to_array(entry, page);
603                 if (status != 0)
604                         break;
605         } while (!entry->eof);
606 
607 out_nopages:
608         if (count == 0 || (status == -EBADCOOKIE && entry->eof != 0)) {
609                 array = nfs_readdir_get_array(page);
610                 if (!IS_ERR(array)) {
611                         array->eof_index = array->size;
612                         status = 0;
613                         nfs_readdir_release_array(page);
614                 } else
615                         status = PTR_ERR(array);
616         }
617 
618         put_page(scratch);
619         return status;
620 }
621 
622 static
623 void nfs_readdir_free_pages(struct page **pages, unsigned int npages)
624 {
625         unsigned int i;
626         for (i = 0; i < npages; i++)
627                 put_page(pages[i]);
628 }
629 
630 /*
631  * nfs_readdir_large_page will allocate pages that must be freed with a call
632  * to nfs_readdir_free_pagearray
633  */
634 static
635 int nfs_readdir_alloc_pages(struct page **pages, unsigned int npages)
636 {
637         unsigned int i;
638 
639         for (i = 0; i < npages; i++) {
640                 struct page *page = alloc_page(GFP_KERNEL);
641                 if (page == NULL)
642                         goto out_freepages;
643                 pages[i] = page;
644         }
645         return 0;
646 
647 out_freepages:
648         nfs_readdir_free_pages(pages, i);
649         return -ENOMEM;
650 }
651 
652 static
653 int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page, struct inode *inode)
654 {
655         struct page *pages[NFS_MAX_READDIR_PAGES];
656         struct nfs_entry entry;
657         struct file     *file = desc->file;
658         struct nfs_cache_array *array;
659         int status = -ENOMEM;
660         unsigned int array_size = ARRAY_SIZE(pages);
661 
662         entry.prev_cookie = 0;
663         entry.cookie = desc->last_cookie;
664         entry.eof = 0;
665         entry.fh = nfs_alloc_fhandle();
666         entry.fattr = nfs_alloc_fattr();
667         entry.server = NFS_SERVER(inode);
668         if (entry.fh == NULL || entry.fattr == NULL)
669                 goto out;
670 
671         entry.label = nfs4_label_alloc(NFS_SERVER(inode), GFP_NOWAIT);
672         if (IS_ERR(entry.label)) {
673                 status = PTR_ERR(entry.label);
674                 goto out;
675         }
676 
677         array = nfs_readdir_get_array(page);
678         if (IS_ERR(array)) {
679                 status = PTR_ERR(array);
680                 goto out_label_free;
681         }
682         memset(array, 0, sizeof(struct nfs_cache_array));
683         atomic_set(&array->refcount, 1);
684         array->eof_index = -1;
685 
686         status = nfs_readdir_alloc_pages(pages, array_size);
687         if (status < 0)
688                 goto out_release_array;
689         do {
690                 unsigned int pglen;
691                 status = nfs_readdir_xdr_filler(pages, desc, &entry, file, inode);
692 
693                 if (status < 0)
694                         break;
695                 pglen = status;
696                 status = nfs_readdir_page_filler(desc, &entry, pages, page, pglen);
697                 if (status < 0) {
698                         if (status == -ENOSPC)
699                                 status = 0;
700                         break;
701                 }
702         } while (array->eof_index < 0);
703 
704         nfs_readdir_free_pages(pages, array_size);
705 out_release_array:
706         nfs_readdir_release_array(page);
707 out_label_free:
708         nfs4_label_free(entry.label);
709 out:
710         nfs_free_fattr(entry.fattr);
711         nfs_free_fhandle(entry.fh);
712         return status;
713 }
714 
715 /*
716  * Now we cache directories properly, by converting xdr information
717  * to an array that can be used for lookups later.  This results in
718  * fewer cache pages, since we can store more information on each page.
719  * We only need to convert from xdr once so future lookups are much simpler
720  */
721 static
722 int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page* page)
723 {
724         struct inode    *inode = file_inode(desc->file);
725         int ret;
726 
727         ret = nfs_readdir_xdr_to_array(desc, page, inode);
728         if (ret < 0)
729                 goto error;
730         SetPageUptodate(page);
731 
732         if (invalidate_inode_pages2_range(inode->i_mapping, page->index + 1, -1) < 0) {
733                 /* Should never happen */
734                 nfs_zap_mapping(inode, inode->i_mapping);
735         }
736         unlock_page(page);
737         return 0;
738  error:
739         unlock_page(page);
740         return ret;
741 }
742 
743 static
744 void cache_page_release(nfs_readdir_descriptor_t *desc)
745 {
746         nfs_readdir_clear_array(desc->page);
747         put_page(desc->page);
748         desc->page = NULL;
749 }
750 
751 static
752 struct page *get_cache_page(nfs_readdir_descriptor_t *desc)
753 {
754         struct page *page;
755 
756         for (;;) {
757                 page = read_cache_page(desc->file->f_mapping,
758                         desc->page_index, (filler_t *)nfs_readdir_filler, desc);
759                 if (IS_ERR(page) || grab_page(page))
760                         break;
761                 put_page(page);
762         }
763         return page;
764 }
765 
766 /*
767  * Returns 0 if desc->dir_cookie was found on page desc->page_index
768  */
769 static
770 int find_cache_page(nfs_readdir_descriptor_t *desc)
771 {
772         int res;
773 
774         desc->page = get_cache_page(desc);
775         if (IS_ERR(desc->page))
776                 return PTR_ERR(desc->page);
777 
778         res = nfs_readdir_search_array(desc);
779         if (res != 0)
780                 cache_page_release(desc);
781         return res;
782 }
783 
784 /* Search for desc->dir_cookie from the beginning of the page cache */
785 static inline
786 int readdir_search_pagecache(nfs_readdir_descriptor_t *desc)
787 {
788         int res;
789 
790         if (desc->page_index == 0) {
791                 desc->current_index = 0;
792                 desc->last_cookie = 0;
793         }
794         do {
795                 res = find_cache_page(desc);
796         } while (res == -EAGAIN);
797         return res;
798 }
799 
800 /*
801  * Once we've found the start of the dirent within a page: fill 'er up...
802  */
803 static 
804 int nfs_do_filldir(nfs_readdir_descriptor_t *desc)
805 {
806         struct file     *file = desc->file;
807         int i = 0;
808         int res = 0;
809         struct nfs_cache_array *array = NULL;
810         struct nfs_open_dir_context *ctx = file->private_data;
811 
812         array = nfs_readdir_get_array(desc->page);
813         if (IS_ERR(array)) {
814                 res = PTR_ERR(array);
815                 goto out;
816         }
817 
818         for (i = desc->cache_entry_index; i < array->size; i++) {
819                 struct nfs_cache_array_entry *ent;
820 
821                 ent = &array->array[i];
822                 if (!dir_emit(desc->ctx, ent->string.name, ent->string.len,
823                     nfs_compat_user_ino64(ent->ino), ent->d_type)) {
824                         desc->eof = 1;
825                         break;
826                 }
827                 desc->ctx->pos++;
828                 if (i < (array->size-1))
829                         *desc->dir_cookie = array->array[i+1].cookie;
830                 else
831                         *desc->dir_cookie = array->last_cookie;
832                 if (ctx->duped != 0)
833                         ctx->duped = 1;
834         }
835         if (array->eof_index >= 0)
836                 desc->eof = 1;
837 
838         nfs_readdir_release_array(desc->page);
839 out:
840         cache_page_release(desc);
841         dfprintk(DIRCACHE, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n",
842                         (unsigned long long)*desc->dir_cookie, res);
843         return res;
844 }
845 
846 /*
847  * If we cannot find a cookie in our cache, we suspect that this is
848  * because it points to a deleted file, so we ask the server to return
849  * whatever it thinks is the next entry. We then feed this to filldir.
850  * If all goes well, we should then be able to find our way round the
851  * cache on the next call to readdir_search_pagecache();
852  *
853  * NOTE: we cannot add the anonymous page to the pagecache because
854  *       the data it contains might not be page aligned. Besides,
855  *       we should already have a complete representation of the
856  *       directory in the page cache by the time we get here.
857  */
858 static inline
859 int uncached_readdir(nfs_readdir_descriptor_t *desc)
860 {
861         struct page     *page = NULL;
862         int             status;
863         struct inode *inode = file_inode(desc->file);
864         struct nfs_open_dir_context *ctx = desc->file->private_data;
865 
866         dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie %Lu\n",
867                         (unsigned long long)*desc->dir_cookie);
868 
869         page = alloc_page(GFP_HIGHUSER);
870         if (!page) {
871                 status = -ENOMEM;
872                 goto out;
873         }
874 
875         desc->page_index = 0;
876         desc->last_cookie = *desc->dir_cookie;
877         desc->page = page;
878         ctx->duped = 0;
879 
880         status = nfs_readdir_xdr_to_array(desc, page, inode);
881         if (status < 0)
882                 goto out_release;
883 
884         status = nfs_do_filldir(desc);
885 
886  out:
887         dfprintk(DIRCACHE, "NFS: %s: returns %d\n",
888                         __func__, status);
889         return status;
890  out_release:
891         cache_page_release(desc);
892         goto out;
893 }
894 
895 /* The file offset position represents the dirent entry number.  A
896    last cookie cache takes care of the common case of reading the
897    whole directory.
898  */
899 static int nfs_readdir(struct file *file, struct dir_context *ctx)
900 {
901         struct dentry   *dentry = file_dentry(file);
902         struct inode    *inode = d_inode(dentry);
903         nfs_readdir_descriptor_t my_desc,
904                         *desc = &my_desc;
905         struct nfs_open_dir_context *dir_ctx = file->private_data;
906         int res = 0;
907 
908         dfprintk(FILE, "NFS: readdir(%pD2) starting at cookie %llu\n",
909                         file, (long long)ctx->pos);
910         nfs_inc_stats(inode, NFSIOS_VFSGETDENTS);
911 
912         /*
913          * ctx->pos points to the dirent entry number.
914          * *desc->dir_cookie has the cookie for the next entry. We have
915          * to either find the entry with the appropriate number or
916          * revalidate the cookie.
917          */
918         memset(desc, 0, sizeof(*desc));
919 
920         desc->file = file;
921         desc->ctx = ctx;
922         desc->dir_cookie = &dir_ctx->dir_cookie;
923         desc->decode = NFS_PROTO(inode)->decode_dirent;
924         desc->plus = nfs_use_readdirplus(inode, ctx) ? 1 : 0;
925 
926         if (ctx->pos == 0 || nfs_attribute_cache_expired(inode))
927                 res = nfs_revalidate_mapping(inode, file->f_mapping);
928         if (res < 0)
929                 goto out;
930 
931         do {
932                 res = readdir_search_pagecache(desc);
933 
934                 if (res == -EBADCOOKIE) {
935                         res = 0;
936                         /* This means either end of directory */
937                         if (*desc->dir_cookie && desc->eof == 0) {
938                                 /* Or that the server has 'lost' a cookie */
939                                 res = uncached_readdir(desc);
940                                 if (res == 0)
941                                         continue;
942                         }
943                         break;
944                 }
945                 if (res == -ETOOSMALL && desc->plus) {
946                         clear_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(inode)->flags);
947                         nfs_zap_caches(inode);
948                         desc->page_index = 0;
949                         desc->plus = 0;
950                         desc->eof = 0;
951                         continue;
952                 }
953                 if (res < 0)
954                         break;
955 
956                 res = nfs_do_filldir(desc);
957                 if (res < 0)
958                         break;
959         } while (!desc->eof);
960 out:
961         if (res > 0)
962                 res = 0;
963         dfprintk(FILE, "NFS: readdir(%pD2) returns %d\n", file, res);
964         return res;
965 }
966 
967 static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence)
968 {
969         struct nfs_open_dir_context *dir_ctx = filp->private_data;
970 
971         dfprintk(FILE, "NFS: llseek dir(%pD2, %lld, %d)\n",
972                         filp, offset, whence);
973 
974         switch (whence) {
975                 case 1:
976                         offset += filp->f_pos;
977                 case 0:
978                         if (offset >= 0)
979                                 break;
980                 default:
981                         return -EINVAL;
982         }
983         if (offset != filp->f_pos) {
984                 filp->f_pos = offset;
985                 dir_ctx->dir_cookie = 0;
986                 dir_ctx->duped = 0;
987         }
988         return offset;
989 }
990 
991 /*
992  * All directory operations under NFS are synchronous, so fsync()
993  * is a dummy operation.
994  */
995 static int nfs_fsync_dir(struct file *filp, loff_t start, loff_t end,
996                          int datasync)
997 {
998         struct inode *inode = file_inode(filp);
999 
1000         dfprintk(FILE, "NFS: fsync dir(%pD2) datasync %d\n", filp, datasync);
1001 
1002         inode_lock(inode);
1003         nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
1004         inode_unlock(inode);
1005         return 0;
1006 }
1007 
1008 /**
1009  * nfs_force_lookup_revalidate - Mark the directory as having changed
1010  * @dir - pointer to directory inode
1011  *
1012  * This forces the revalidation code in nfs_lookup_revalidate() to do a
1013  * full lookup on all child dentries of 'dir' whenever a change occurs
1014  * on the server that might have invalidated our dcache.
1015  *
1016  * The caller should be holding dir->i_lock
1017  */
1018 void nfs_force_lookup_revalidate(struct inode *dir)
1019 {
1020         NFS_I(dir)->cache_change_attribute++;
1021 }
1022 EXPORT_SYMBOL_GPL(nfs_force_lookup_revalidate);
1023 
1024 /*
1025  * A check for whether or not the parent directory has changed.
1026  * In the case it has, we assume that the dentries are untrustworthy
1027  * and may need to be looked up again.
1028  * If rcu_walk prevents us from performing a full check, return 0.
1029  */
1030 static int nfs_check_verifier(struct inode *dir, struct dentry *dentry,
1031                               int rcu_walk)
1032 {
1033         if (IS_ROOT(dentry))
1034                 return 1;
1035         if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
1036                 return 0;
1037         if (!nfs_verify_change_attribute(dir, dentry->d_time))
1038                 return 0;
1039         /* Revalidate nfsi->cache_change_attribute before we declare a match */
1040         if (nfs_mapping_need_revalidate_inode(dir)) {
1041                 if (rcu_walk)
1042                         return 0;
1043                 if (__nfs_revalidate_inode(NFS_SERVER(dir), dir) < 0)
1044                         return 0;
1045         }
1046         if (!nfs_verify_change_attribute(dir, dentry->d_time))
1047                 return 0;
1048         return 1;
1049 }
1050 
1051 /*
1052  * Use intent information to check whether or not we're going to do
1053  * an O_EXCL create using this path component.
1054  */
1055 static int nfs_is_exclusive_create(struct inode *dir, unsigned int flags)
1056 {
1057         if (NFS_PROTO(dir)->version == 2)
1058                 return 0;
1059         return flags & LOOKUP_EXCL;
1060 }
1061 
1062 /*
1063  * Inode and filehandle revalidation for lookups.
1064  *
1065  * We force revalidation in the cases where the VFS sets LOOKUP_REVAL,
1066  * or if the intent information indicates that we're about to open this
1067  * particular file and the "nocto" mount flag is not set.
1068  *
1069  */
1070 static
1071 int nfs_lookup_verify_inode(struct inode *inode, unsigned int flags)
1072 {
1073         struct nfs_server *server = NFS_SERVER(inode);
1074         int ret;
1075 
1076         if (IS_AUTOMOUNT(inode))
1077                 return 0;
1078         /* VFS wants an on-the-wire revalidation */
1079         if (flags & LOOKUP_REVAL)
1080                 goto out_force;
1081         /* This is an open(2) */
1082         if ((flags & LOOKUP_OPEN) && !(server->flags & NFS_MOUNT_NOCTO) &&
1083             (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
1084                 goto out_force;
1085 out:
1086         return (inode->i_nlink == 0) ? -ENOENT : 0;
1087 out_force:
1088         if (flags & LOOKUP_RCU)
1089                 return -ECHILD;
1090         ret = __nfs_revalidate_inode(server, inode);
1091         if (ret != 0)
1092                 return ret;
1093         goto out;
1094 }
1095 
1096 /*
1097  * We judge how long we want to trust negative
1098  * dentries by looking at the parent inode mtime.
1099  *
1100  * If parent mtime has changed, we revalidate, else we wait for a
1101  * period corresponding to the parent's attribute cache timeout value.
1102  *
1103  * If LOOKUP_RCU prevents us from performing a full check, return 1
1104  * suggesting a reval is needed.
1105  */
1106 static inline
1107 int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry,
1108                        unsigned int flags)
1109 {
1110         /* Don't revalidate a negative dentry if we're creating a new file */
1111         if (flags & LOOKUP_CREATE)
1112                 return 0;
1113         if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG)
1114                 return 1;
1115         return !nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU);
1116 }
1117 
1118 /*
1119  * This is called every time the dcache has a lookup hit,
1120  * and we should check whether we can really trust that
1121  * lookup.
1122  *
1123  * NOTE! The hit can be a negative hit too, don't assume
1124  * we have an inode!
1125  *
1126  * If the parent directory is seen to have changed, we throw out the
1127  * cached dentry and do a new lookup.
1128  */
1129 static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
1130 {
1131         struct inode *dir;
1132         struct inode *inode;
1133         struct dentry *parent;
1134         struct nfs_fh *fhandle = NULL;
1135         struct nfs_fattr *fattr = NULL;
1136         struct nfs4_label *label = NULL;
1137         int error;
1138 
1139         if (flags & LOOKUP_RCU) {
1140                 parent = ACCESS_ONCE(dentry->d_parent);
1141                 dir = d_inode_rcu(parent);
1142                 if (!dir)
1143                         return -ECHILD;
1144         } else {
1145                 parent = dget_parent(dentry);
1146                 dir = d_inode(parent);
1147         }
1148         nfs_inc_stats(dir, NFSIOS_DENTRYREVALIDATE);
1149         inode = d_inode(dentry);
1150 
1151         if (!inode) {
1152                 if (nfs_neg_need_reval(dir, dentry, flags)) {
1153                         if (flags & LOOKUP_RCU)
1154                                 return -ECHILD;
1155                         goto out_bad;
1156                 }
1157                 goto out_valid;
1158         }
1159 
1160         if (is_bad_inode(inode)) {
1161                 if (flags & LOOKUP_RCU)
1162                         return -ECHILD;
1163                 dfprintk(LOOKUPCACHE, "%s: %pd2 has dud inode\n",
1164                                 __func__, dentry);
1165                 goto out_bad;
1166         }
1167 
1168         if (NFS_PROTO(dir)->have_delegation(inode, FMODE_READ))
1169                 goto out_set_verifier;
1170 
1171         /* Force a full look up iff the parent directory has changed */
1172         if (!nfs_is_exclusive_create(dir, flags) &&
1173             nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) {
1174 
1175                 if (nfs_lookup_verify_inode(inode, flags)) {
1176                         if (flags & LOOKUP_RCU)
1177                                 return -ECHILD;
1178                         goto out_zap_parent;
1179                 }
1180                 nfs_advise_use_readdirplus(dir);
1181                 goto out_valid;
1182         }
1183 
1184         if (flags & LOOKUP_RCU)
1185                 return -ECHILD;
1186 
1187         if (NFS_STALE(inode))
1188                 goto out_bad;
1189 
1190         error = -ENOMEM;
1191         fhandle = nfs_alloc_fhandle();
1192         fattr = nfs_alloc_fattr();
1193         if (fhandle == NULL || fattr == NULL)
1194                 goto out_error;
1195 
1196         label = nfs4_label_alloc(NFS_SERVER(inode), GFP_NOWAIT);
1197         if (IS_ERR(label))
1198                 goto out_error;
1199 
1200         trace_nfs_lookup_revalidate_enter(dir, dentry, flags);
1201         error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, label);
1202         trace_nfs_lookup_revalidate_exit(dir, dentry, flags, error);
1203         if (error)
1204                 goto out_bad;
1205         if (nfs_compare_fh(NFS_FH(inode), fhandle))
1206                 goto out_bad;
1207         if ((error = nfs_refresh_inode(inode, fattr)) != 0)
1208                 goto out_bad;
1209 
1210         nfs_setsecurity(inode, fattr, label);
1211 
1212         nfs_free_fattr(fattr);
1213         nfs_free_fhandle(fhandle);
1214         nfs4_label_free(label);
1215 
1216         /* set a readdirplus hint that we had a cache miss */
1217         nfs_force_use_readdirplus(dir);
1218 
1219 out_set_verifier:
1220         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
1221  out_valid:
1222         if (flags & LOOKUP_RCU) {
1223                 if (parent != ACCESS_ONCE(dentry->d_parent))
1224                         return -ECHILD;
1225         } else
1226                 dput(parent);
1227         dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is valid\n",
1228                         __func__, dentry);
1229         return 1;
1230 out_zap_parent:
1231         nfs_zap_caches(dir);
1232  out_bad:
1233         WARN_ON(flags & LOOKUP_RCU);
1234         nfs_free_fattr(fattr);
1235         nfs_free_fhandle(fhandle);
1236         nfs4_label_free(label);
1237         nfs_mark_for_revalidate(dir);
1238         if (inode && S_ISDIR(inode->i_mode)) {
1239                 /* Purge readdir caches. */
1240                 nfs_zap_caches(inode);
1241                 /*
1242                  * We can't d_drop the root of a disconnected tree:
1243                  * its d_hash is on the s_anon list and d_drop() would hide
1244                  * it from shrink_dcache_for_unmount(), leading to busy
1245                  * inodes on unmount and further oopses.
1246                  */
1247                 if (IS_ROOT(dentry))
1248                         goto out_valid;
1249         }
1250         dput(parent);
1251         dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is invalid\n",
1252                         __func__, dentry);
1253         return 0;
1254 out_error:
1255         WARN_ON(flags & LOOKUP_RCU);
1256         nfs_free_fattr(fattr);
1257         nfs_free_fhandle(fhandle);
1258         nfs4_label_free(label);
1259         dput(parent);
1260         dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) lookup returned error %d\n",
1261                         __func__, dentry, error);
1262         return error;
1263 }
1264 
1265 /*
1266  * A weaker form of d_revalidate for revalidating just the d_inode(dentry)
1267  * when we don't really care about the dentry name. This is called when a
1268  * pathwalk ends on a dentry that was not found via a normal lookup in the
1269  * parent dir (e.g.: ".", "..", procfs symlinks or mountpoint traversals).
1270  *
1271  * In this situation, we just want to verify that the inode itself is OK
1272  * since the dentry might have changed on the server.
1273  */
1274 static int nfs_weak_revalidate(struct dentry *dentry, unsigned int flags)
1275 {
1276         struct inode *inode = d_inode(dentry);
1277         int error = 0;
1278 
1279         /*
1280          * I believe we can only get a negative dentry here in the case of a
1281          * procfs-style symlink. Just assume it's correct for now, but we may
1282          * eventually need to do something more here.
1283          */
1284         if (!inode) {
1285                 dfprintk(LOOKUPCACHE, "%s: %pd2 has negative inode\n",
1286                                 __func__, dentry);
1287                 return 1;
1288         }
1289 
1290         if (is_bad_inode(inode)) {
1291                 dfprintk(LOOKUPCACHE, "%s: %pd2 has dud inode\n",
1292                                 __func__, dentry);
1293                 return 0;
1294         }
1295 
1296         if (nfs_mapping_need_revalidate_inode(inode))
1297                 error = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
1298         dfprintk(LOOKUPCACHE, "NFS: %s: inode %lu is %s\n",
1299                         __func__, inode->i_ino, error ? "invalid" : "valid");
1300         return !error;
1301 }
1302 
1303 /*
1304  * This is called from dput() when d_count is going to 0.
1305  */
1306 static int nfs_dentry_delete(const struct dentry *dentry)
1307 {
1308         dfprintk(VFS, "NFS: dentry_delete(%pd2, %x)\n",
1309                 dentry, dentry->d_flags);
1310 
1311         /* Unhash any dentry with a stale inode */
1312         if (d_really_is_positive(dentry) && NFS_STALE(d_inode(dentry)))
1313                 return 1;
1314 
1315         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
1316                 /* Unhash it, so that ->d_iput() would be called */
1317                 return 1;
1318         }
1319         if (!(dentry->d_sb->s_flags & MS_ACTIVE)) {
1320                 /* Unhash it, so that ancestors of killed async unlink
1321                  * files will be cleaned up during umount */
1322                 return 1;
1323         }
1324         return 0;
1325 
1326 }
1327 
1328 /* Ensure that we revalidate inode->i_nlink */
1329 static void nfs_drop_nlink(struct inode *inode)
1330 {
1331         spin_lock(&inode->i_lock);
1332         /* drop the inode if we're reasonably sure this is the last link */
1333         if (inode->i_nlink == 1)
1334                 clear_nlink(inode);
1335         NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ATTR;
1336         spin_unlock(&inode->i_lock);
1337 }
1338 
1339 /*
1340  * Called when the dentry loses inode.
1341  * We use it to clean up silly-renamed files.
1342  */
1343 static void nfs_dentry_iput(struct dentry *dentry, struct inode *inode)
1344 {
1345         if (S_ISDIR(inode->i_mode))
1346                 /* drop any readdir cache as it could easily be old */
1347                 NFS_I(inode)->cache_validity |= NFS_INO_INVALID_DATA;
1348 
1349         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
1350                 nfs_complete_unlink(dentry, inode);
1351                 nfs_drop_nlink(inode);
1352         }
1353         iput(inode);
1354 }
1355 
1356 static void nfs_d_release(struct dentry *dentry)
1357 {
1358         /* free cached devname value, if it survived that far */
1359         if (unlikely(dentry->d_fsdata)) {
1360                 if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
1361                         WARN_ON(1);
1362                 else
1363                         kfree(dentry->d_fsdata);
1364         }
1365 }
1366 
1367 const struct dentry_operations nfs_dentry_operations = {
1368         .d_revalidate   = nfs_lookup_revalidate,
1369         .d_weak_revalidate      = nfs_weak_revalidate,
1370         .d_delete       = nfs_dentry_delete,
1371         .d_iput         = nfs_dentry_iput,
1372         .d_automount    = nfs_d_automount,
1373         .d_release      = nfs_d_release,
1374 };
1375 EXPORT_SYMBOL_GPL(nfs_dentry_operations);
1376 
1377 struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
1378 {
1379         struct dentry *res;
1380         struct inode *inode = NULL;
1381         struct nfs_fh *fhandle = NULL;
1382         struct nfs_fattr *fattr = NULL;
1383         struct nfs4_label *label = NULL;
1384         int error;
1385 
1386         dfprintk(VFS, "NFS: lookup(%pd2)\n", dentry);
1387         nfs_inc_stats(dir, NFSIOS_VFSLOOKUP);
1388 
1389         if (unlikely(dentry->d_name.len > NFS_SERVER(dir)->namelen))
1390                 return ERR_PTR(-ENAMETOOLONG);
1391 
1392         /*
1393          * If we're doing an exclusive create, optimize away the lookup
1394          * but don't hash the dentry.
1395          */
1396         if (nfs_is_exclusive_create(dir, flags))
1397                 return NULL;
1398 
1399         res = ERR_PTR(-ENOMEM);
1400         fhandle = nfs_alloc_fhandle();
1401         fattr = nfs_alloc_fattr();
1402         if (fhandle == NULL || fattr == NULL)
1403                 goto out;
1404 
1405         label = nfs4_label_alloc(NFS_SERVER(dir), GFP_NOWAIT);
1406         if (IS_ERR(label))
1407                 goto out;
1408 
1409         trace_nfs_lookup_enter(dir, dentry, flags);
1410         error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, label);
1411         if (error == -ENOENT)
1412                 goto no_entry;
1413         if (error < 0) {
1414                 res = ERR_PTR(error);
1415                 goto out_label;
1416         }
1417         inode = nfs_fhget(dentry->d_sb, fhandle, fattr, label);
1418         res = ERR_CAST(inode);
1419         if (IS_ERR(res))
1420                 goto out_label;
1421 
1422         /* Notify readdir to use READDIRPLUS */
1423         nfs_force_use_readdirplus(dir);
1424 
1425 no_entry:
1426         res = d_splice_alias(inode, dentry);
1427         if (res != NULL) {
1428                 if (IS_ERR(res))
1429                         goto out_label;
1430                 dentry = res;
1431         }
1432         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
1433 out_label:
1434         trace_nfs_lookup_exit(dir, dentry, flags, error);
1435         nfs4_label_free(label);
1436 out:
1437         nfs_free_fattr(fattr);
1438         nfs_free_fhandle(fhandle);
1439         return res;
1440 }
1441 EXPORT_SYMBOL_GPL(nfs_lookup);
1442 
1443 #if IS_ENABLED(CONFIG_NFS_V4)
1444 static int nfs4_lookup_revalidate(struct dentry *, unsigned int);
1445 
1446 const struct dentry_operations nfs4_dentry_operations = {
1447         .d_revalidate   = nfs4_lookup_revalidate,
1448         .d_delete       = nfs_dentry_delete,
1449         .d_iput         = nfs_dentry_iput,
1450         .d_automount    = nfs_d_automount,
1451         .d_release      = nfs_d_release,
1452 };
1453 EXPORT_SYMBOL_GPL(nfs4_dentry_operations);
1454 
1455 static fmode_t flags_to_mode(int flags)
1456 {
1457         fmode_t res = (__force fmode_t)flags & FMODE_EXEC;
1458         if ((flags & O_ACCMODE) != O_WRONLY)
1459                 res |= FMODE_READ;
1460         if ((flags & O_ACCMODE) != O_RDONLY)
1461                 res |= FMODE_WRITE;
1462         return res;
1463 }
1464 
1465 static struct nfs_open_context *create_nfs_open_context(struct dentry *dentry, int open_flags, struct file *filp)
1466 {
1467         return alloc_nfs_open_context(dentry, flags_to_mode(open_flags), filp);
1468 }
1469 
1470 static int do_open(struct inode *inode, struct file *filp)
1471 {
1472         nfs_fscache_open_file(inode, filp);
1473         return 0;
1474 }
1475 
1476 static int nfs_finish_open(struct nfs_open_context *ctx,
1477                            struct dentry *dentry,
1478                            struct file *file, unsigned open_flags,
1479                            int *opened)
1480 {
1481         int err;
1482 
1483         err = finish_open(file, dentry, do_open, opened);
1484         if (err)
1485                 goto out;
1486         nfs_file_set_open_context(file, ctx);
1487 
1488 out:
1489         return err;
1490 }
1491 
1492 int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
1493                     struct file *file, unsigned open_flags,
1494                     umode_t mode, int *opened)
1495 {
1496         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
1497         struct nfs_open_context *ctx;
1498         struct dentry *res;
1499         struct iattr attr = { .ia_valid = ATTR_OPEN };
1500         struct inode *inode;
1501         unsigned int lookup_flags = 0;
1502         bool switched = false;
1503         int err;
1504 
1505         /* Expect a negative dentry */
1506         BUG_ON(d_inode(dentry));
1507 
1508         dfprintk(VFS, "NFS: atomic_open(%s/%lu), %pd\n",
1509                         dir->i_sb->s_id, dir->i_ino, dentry);
1510 
1511         err = nfs_check_flags(open_flags);
1512         if (err)
1513                 return err;
1514 
1515         /* NFS only supports OPEN on regular files */
1516         if ((open_flags & O_DIRECTORY)) {
1517                 if (!d_in_lookup(dentry)) {
1518                         /*
1519                          * Hashed negative dentry with O_DIRECTORY: dentry was
1520                          * revalidated and is fine, no need to perform lookup
1521                          * again
1522                          */
1523                         return -ENOENT;
1524                 }
1525                 lookup_flags = LOOKUP_OPEN|LOOKUP_DIRECTORY;
1526                 goto no_open;
1527         }
1528 
1529         if (dentry->d_name.len > NFS_SERVER(dir)->namelen)
1530                 return -ENAMETOOLONG;
1531 
1532         if (open_flags & O_CREAT) {
1533                 struct nfs_server *server = NFS_SERVER(dir);
1534 
1535                 if (!(server->attr_bitmask[2] & FATTR4_WORD2_MODE_UMASK))
1536                         mode &= ~current_umask();
1537 
1538                 attr.ia_valid |= ATTR_MODE;
1539                 attr.ia_mode = mode;
1540         }
1541         if (open_flags & O_TRUNC) {
1542                 attr.ia_valid |= ATTR_SIZE;
1543                 attr.ia_size = 0;
1544         }
1545 
1546         if (!(open_flags & O_CREAT) && !d_in_lookup(dentry)) {
1547                 d_drop(dentry);
1548                 switched = true;
1549                 dentry = d_alloc_parallel(dentry->d_parent,
1550                                           &dentry->d_name, &wq);
1551                 if (IS_ERR(dentry))
1552                         return PTR_ERR(dentry);
1553                 if (unlikely(!d_in_lookup(dentry)))
1554                         return finish_no_open(file, dentry);
1555         }
1556 
1557         ctx = create_nfs_open_context(dentry, open_flags, file);
1558         err = PTR_ERR(ctx);
1559         if (IS_ERR(ctx))
1560                 goto out;
1561 
1562         trace_nfs_atomic_open_enter(dir, ctx, open_flags);
1563         inode = NFS_PROTO(dir)->open_context(dir, ctx, open_flags, &attr, opened);
1564         if (IS_ERR(inode)) {
1565                 err = PTR_ERR(inode);
1566                 trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
1567                 put_nfs_open_context(ctx);
1568                 d_drop(dentry);
1569                 switch (err) {
1570                 case -ENOENT:
1571                         d_add(dentry, NULL);
1572                         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
1573                         break;
1574                 case -EISDIR:
1575                 case -ENOTDIR:
1576                         goto no_open;
1577                 case -ELOOP:
1578                         if (!(open_flags & O_NOFOLLOW))
1579                                 goto no_open;
1580                         break;
1581                         /* case -EINVAL: */
1582                 default:
1583                         break;
1584                 }
1585                 goto out;
1586         }
1587 
1588         err = nfs_finish_open(ctx, ctx->dentry, file, open_flags, opened);
1589         trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
1590         put_nfs_open_context(ctx);
1591 out:
1592         if (unlikely(switched)) {
1593                 d_lookup_done(dentry);
1594                 dput(dentry);
1595         }
1596         return err;
1597 
1598 no_open:
1599         res = nfs_lookup(dir, dentry, lookup_flags);
1600         if (switched) {
1601                 d_lookup_done(dentry);
1602                 if (!res)
1603                         res = dentry;
1604                 else
1605                         dput(dentry);
1606         }
1607         if (IS_ERR(res))
1608                 return PTR_ERR(res);
1609         return finish_no_open(file, res);
1610 }
1611 EXPORT_SYMBOL_GPL(nfs_atomic_open);
1612 
1613 static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
1614 {
1615         struct inode *inode;
1616         int ret = 0;
1617 
1618         if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY))
1619                 goto no_open;
1620         if (d_mountpoint(dentry))
1621                 goto no_open;
1622         if (NFS_SB(dentry->d_sb)->caps & NFS_CAP_ATOMIC_OPEN_V1)
1623                 goto no_open;
1624 
1625         inode = d_inode(dentry);
1626 
1627         /* We can't create new files in nfs_open_revalidate(), so we
1628          * optimize away revalidation of negative dentries.
1629          */
1630         if (inode == NULL) {
1631                 struct dentry *parent;
1632                 struct inode *dir;
1633 
1634                 if (flags & LOOKUP_RCU) {
1635                         parent = ACCESS_ONCE(dentry->d_parent);
1636                         dir = d_inode_rcu(parent);
1637                         if (!dir)
1638                                 return -ECHILD;
1639                 } else {
1640                         parent = dget_parent(dentry);
1641                         dir = d_inode(parent);
1642                 }
1643                 if (!nfs_neg_need_reval(dir, dentry, flags))
1644                         ret = 1;
1645                 else if (flags & LOOKUP_RCU)
1646                         ret = -ECHILD;
1647                 if (!(flags & LOOKUP_RCU))
1648                         dput(parent);
1649                 else if (parent != ACCESS_ONCE(dentry->d_parent))
1650                         return -ECHILD;
1651                 goto out;
1652         }
1653 
1654         /* NFS only supports OPEN on regular files */
1655         if (!S_ISREG(inode->i_mode))
1656                 goto no_open;
1657         /* We cannot do exclusive creation on a positive dentry */
1658         if (flags & LOOKUP_EXCL)
1659                 goto no_open;
1660 
1661         /* Let f_op->open() actually open (and revalidate) the file */
1662         ret = 1;
1663 
1664 out:
1665         return ret;
1666 
1667 no_open:
1668         return nfs_lookup_revalidate(dentry, flags);
1669 }
1670 
1671 #endif /* CONFIG_NFSV4 */
1672 
1673 /*
1674  * Code common to create, mkdir, and mknod.
1675  */
1676 int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
1677                                 struct nfs_fattr *fattr,
1678                                 struct nfs4_label *label)
1679 {
1680         struct dentry *parent = dget_parent(dentry);
1681         struct inode *dir = d_inode(parent);
1682         struct inode *inode;
1683         int error = -EACCES;
1684 
1685         d_drop(dentry);
1686 
1687         /* We may have been initialized further down */
1688         if (d_really_is_positive(dentry))
1689                 goto out;
1690         if (fhandle->size == 0) {
1691                 error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, NULL);
1692                 if (error)
1693                         goto out_error;
1694         }
1695         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
1696         if (!(fattr->valid & NFS_ATTR_FATTR)) {
1697                 struct nfs_server *server = NFS_SB(dentry->d_sb);
1698                 error = server->nfs_client->rpc_ops->getattr(server, fhandle, fattr, NULL);
1699                 if (error < 0)
1700                         goto out_error;
1701         }
1702         inode = nfs_fhget(dentry->d_sb, fhandle, fattr, label);
1703         error = PTR_ERR(inode);
1704         if (IS_ERR(inode))
1705                 goto out_error;
1706         d_add(dentry, inode);
1707 out:
1708         dput(parent);
1709         return 0;
1710 out_error:
1711         nfs_mark_for_revalidate(dir);
1712         dput(parent);
1713         return error;
1714 }
1715 EXPORT_SYMBOL_GPL(nfs_instantiate);
1716 
1717 /*
1718  * Following a failed create operation, we drop the dentry rather
1719  * than retain a negative dentry. This avoids a problem in the event
1720  * that the operation succeeded on the server, but an error in the
1721  * reply path made it appear to have failed.
1722  */
1723 int nfs_create(struct inode *dir, struct dentry *dentry,
1724                 umode_t mode, bool excl)
1725 {
1726         struct iattr attr;
1727         int open_flags = excl ? O_CREAT | O_EXCL : O_CREAT;
1728         int error;
1729 
1730         dfprintk(VFS, "NFS: create(%s/%lu), %pd\n",
1731                         dir->i_sb->s_id, dir->i_ino, dentry);
1732 
1733         attr.ia_mode = mode;
1734         attr.ia_valid = ATTR_MODE;
1735 
1736         trace_nfs_create_enter(dir, dentry, open_flags);
1737         error = NFS_PROTO(dir)->create(dir, dentry, &attr, open_flags);
1738         trace_nfs_create_exit(dir, dentry, open_flags, error);
1739         if (error != 0)
1740                 goto out_err;
1741         return 0;
1742 out_err:
1743         d_drop(dentry);
1744         return error;
1745 }
1746 EXPORT_SYMBOL_GPL(nfs_create);
1747 
1748 /*
1749  * See comments for nfs_proc_create regarding failed operations.
1750  */
1751 int
1752 nfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
1753 {
1754         struct iattr attr;
1755         int status;
1756 
1757         dfprintk(VFS, "NFS: mknod(%s/%lu), %pd\n",
1758                         dir->i_sb->s_id, dir->i_ino, dentry);
1759 
1760         attr.ia_mode = mode;
1761         attr.ia_valid = ATTR_MODE;
1762 
1763         trace_nfs_mknod_enter(dir, dentry);
1764         status = NFS_PROTO(dir)->mknod(dir, dentry, &attr, rdev);
1765         trace_nfs_mknod_exit(dir, dentry, status);
1766         if (status != 0)
1767                 goto out_err;
1768         return 0;
1769 out_err:
1770         d_drop(dentry);
1771         return status;
1772 }
1773 EXPORT_SYMBOL_GPL(nfs_mknod);
1774 
1775 /*
1776  * See comments for nfs_proc_create regarding failed operations.
1777  */
1778 int nfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1779 {
1780         struct iattr attr;
1781         int error;
1782 
1783         dfprintk(VFS, "NFS: mkdir(%s/%lu), %pd\n",
1784                         dir->i_sb->s_id, dir->i_ino, dentry);
1785 
1786         attr.ia_valid = ATTR_MODE;
1787         attr.ia_mode = mode | S_IFDIR;
1788 
1789         trace_nfs_mkdir_enter(dir, dentry);
1790         error = NFS_PROTO(dir)->mkdir(dir, dentry, &attr);
1791         trace_nfs_mkdir_exit(dir, dentry, error);
1792         if (error != 0)
1793                 goto out_err;
1794         return 0;
1795 out_err:
1796         d_drop(dentry);
1797         return error;
1798 }
1799 EXPORT_SYMBOL_GPL(nfs_mkdir);
1800 
1801 static void nfs_dentry_handle_enoent(struct dentry *dentry)
1802 {
1803         if (simple_positive(dentry))
1804                 d_delete(dentry);
1805 }
1806 
1807 int nfs_rmdir(struct inode *dir, struct dentry *dentry)
1808 {
1809         int error;
1810 
1811         dfprintk(VFS, "NFS: rmdir(%s/%lu), %pd\n",
1812                         dir->i_sb->s_id, dir->i_ino, dentry);
1813 
1814         trace_nfs_rmdir_enter(dir, dentry);
1815         if (d_really_is_positive(dentry)) {
1816                 down_write(&NFS_I(d_inode(dentry))->rmdir_sem);
1817                 error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
1818                 /* Ensure the VFS deletes this inode */
1819                 switch (error) {
1820                 case 0:
1821                         clear_nlink(d_inode(dentry));
1822                         break;
1823                 case -ENOENT:
1824                         nfs_dentry_handle_enoent(dentry);
1825                 }
1826                 up_write(&NFS_I(d_inode(dentry))->rmdir_sem);
1827         } else
1828                 error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
1829         trace_nfs_rmdir_exit(dir, dentry, error);
1830 
1831         return error;
1832 }
1833 EXPORT_SYMBOL_GPL(nfs_rmdir);
1834 
1835 /*
1836  * Remove a file after making sure there are no pending writes,
1837  * and after checking that the file has only one user. 
1838  *
1839  * We invalidate the attribute cache and free the inode prior to the operation
1840  * to avoid possible races if the server reuses the inode.
1841  */
1842 static int nfs_safe_remove(struct dentry *dentry)
1843 {
1844         struct inode *dir = d_inode(dentry->d_parent);
1845         struct inode *inode = d_inode(dentry);
1846         int error = -EBUSY;
1847                 
1848         dfprintk(VFS, "NFS: safe_remove(%pd2)\n", dentry);
1849 
1850         /* If the dentry was sillyrenamed, we simply call d_delete() */
1851         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
1852                 error = 0;
1853                 goto out;
1854         }
1855 
1856         trace_nfs_remove_enter(dir, dentry);
1857         if (inode != NULL) {
1858                 NFS_PROTO(inode)->return_delegation(inode);
1859                 error = NFS_PROTO(dir)->remove(dir, &dentry->d_name);
1860                 if (error == 0)
1861                         nfs_drop_nlink(inode);
1862         } else
1863                 error = NFS_PROTO(dir)->remove(dir, &dentry->d_name);
1864         if (error == -ENOENT)
1865                 nfs_dentry_handle_enoent(dentry);
1866         trace_nfs_remove_exit(dir, dentry, error);
1867 out:
1868         return error;
1869 }
1870 
1871 /*  We do silly rename. In case sillyrename() returns -EBUSY, the inode
1872  *  belongs to an active ".nfs..." file and we return -EBUSY.
1873  *
1874  *  If sillyrename() returns 0, we do nothing, otherwise we unlink.
1875  */
1876 int nfs_unlink(struct inode *dir, struct dentry *dentry)
1877 {
1878         int error;
1879         int need_rehash = 0;
1880 
1881         dfprintk(VFS, "NFS: unlink(%s/%lu, %pd)\n", dir->i_sb->s_id,
1882                 dir->i_ino, dentry);
1883 
1884         trace_nfs_unlink_enter(dir, dentry);
1885         spin_lock(&dentry->d_lock);
1886         if (d_count(dentry) > 1) {
1887                 spin_unlock(&dentry->d_lock);
1888                 /* Start asynchronous writeout of the inode */
1889                 write_inode_now(d_inode(dentry), 0);
1890                 error = nfs_sillyrename(dir, dentry);
1891                 goto out;
1892         }
1893         if (!d_unhashed(dentry)) {
1894                 __d_drop(dentry);
1895                 need_rehash = 1;
1896         }
1897         spin_unlock(&dentry->d_lock);
1898         error = nfs_safe_remove(dentry);
1899         if (!error || error == -ENOENT) {
1900                 nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
1901         } else if (need_rehash)
1902                 d_rehash(dentry);
1903 out:
1904         trace_nfs_unlink_exit(dir, dentry, error);
1905         return error;
1906 }
1907 EXPORT_SYMBOL_GPL(nfs_unlink);
1908 
1909 /*
1910  * To create a symbolic link, most file systems instantiate a new inode,
1911  * add a page to it containing the path, then write it out to the disk
1912  * using prepare_write/commit_write.
1913  *
1914  * Unfortunately the NFS client can't create the in-core inode first
1915  * because it needs a file handle to create an in-core inode (see
1916  * fs/nfs/inode.c:nfs_fhget).  We only have a file handle *after* the
1917  * symlink request has completed on the server.
1918  *
1919  * So instead we allocate a raw page, copy the symname into it, then do
1920  * the SYMLINK request with the page as the buffer.  If it succeeds, we
1921  * now have a new file handle and can instantiate an in-core NFS inode
1922  * and move the raw page into its mapping.
1923  */
1924 int nfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1925 {
1926         struct page *page;
1927         char *kaddr;
1928         struct iattr attr;
1929         unsigned int pathlen = strlen(symname);
1930         int error;
1931 
1932         dfprintk(VFS, "NFS: symlink(%s/%lu, %pd, %s)\n", dir->i_sb->s_id,
1933                 dir->i_ino, dentry, symname);
1934 
1935         if (pathlen > PAGE_SIZE)
1936                 return -ENAMETOOLONG;
1937 
1938         attr.ia_mode = S_IFLNK | S_IRWXUGO;
1939         attr.ia_valid = ATTR_MODE;
1940 
1941         page = alloc_page(GFP_USER);
1942         if (!page)
1943                 return -ENOMEM;
1944 
1945         kaddr = page_address(page);
1946         memcpy(kaddr, symname, pathlen);
1947         if (pathlen < PAGE_SIZE)
1948                 memset(kaddr + pathlen, 0, PAGE_SIZE - pathlen);
1949 
1950         trace_nfs_symlink_enter(dir, dentry);
1951         error = NFS_PROTO(dir)->symlink(dir, dentry, page, pathlen, &attr);
1952         trace_nfs_symlink_exit(dir, dentry, error);
1953         if (error != 0) {
1954                 dfprintk(VFS, "NFS: symlink(%s/%lu, %pd, %s) error %d\n",
1955                         dir->i_sb->s_id, dir->i_ino,
1956                         dentry, symname, error);
1957                 d_drop(dentry);
1958                 __free_page(page);
1959                 return error;
1960         }
1961 
1962         /*
1963          * No big deal if we can't add this page to the page cache here.
1964          * READLINK will get the missing page from the server if needed.
1965          */
1966         if (!add_to_page_cache_lru(page, d_inode(dentry)->i_mapping, 0,
1967                                                         GFP_KERNEL)) {
1968                 SetPageUptodate(page);
1969                 unlock_page(page);
1970                 /*
1971                  * add_to_page_cache_lru() grabs an extra page refcount.
1972                  * Drop it here to avoid leaking this page later.
1973                  */
1974                 put_page(page);
1975         } else
1976                 __free_page(page);
1977 
1978         return 0;
1979 }
1980 EXPORT_SYMBOL_GPL(nfs_symlink);
1981 
1982 int
1983 nfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1984 {
1985         struct inode *inode = d_inode(old_dentry);
1986         int error;
1987 
1988         dfprintk(VFS, "NFS: link(%pd2 -> %pd2)\n",
1989                 old_dentry, dentry);
1990 
1991         trace_nfs_link_enter(inode, dir, dentry);
1992         NFS_PROTO(inode)->return_delegation(inode);
1993 
1994         d_drop(dentry);
1995         error = NFS_PROTO(dir)->link(inode, dir, &dentry->d_name);
1996         if (error == 0) {
1997                 ihold(inode);
1998                 d_add(dentry, inode);
1999         }
2000         trace_nfs_link_exit(inode, dir, dentry, error);
2001         return error;
2002 }
2003 EXPORT_SYMBOL_GPL(nfs_link);
2004 
2005 /*
2006  * RENAME
2007  * FIXME: Some nfsds, like the Linux user space nfsd, may generate a
2008  * different file handle for the same inode after a rename (e.g. when
2009  * moving to a different directory). A fail-safe method to do so would
2010  * be to look up old_dir/old_name, create a link to new_dir/new_name and
2011  * rename the old file using the sillyrename stuff. This way, the original
2012  * file in old_dir will go away when the last process iput()s the inode.
2013  *
2014  * FIXED.
2015  * 
2016  * It actually works quite well. One needs to have the possibility for
2017  * at least one ".nfs..." file in each directory the file ever gets
2018  * moved or linked to which happens automagically with the new
2019  * implementation that only depends on the dcache stuff instead of
2020  * using the inode layer
2021  *
2022  * Unfortunately, things are a little more complicated than indicated
2023  * above. For a cross-directory move, we want to make sure we can get
2024  * rid of the old inode after the operation.  This means there must be
2025  * no pending writes (if it's a file), and the use count must be 1.
2026  * If these conditions are met, we can drop the dentries before doing
2027  * the rename.
2028  */
2029 int nfs_rename(struct inode *old_dir, struct dentry *old_dentry,
2030                struct inode *new_dir, struct dentry *new_dentry,
2031                unsigned int flags)
2032 {
2033         struct inode *old_inode = d_inode(old_dentry);
2034         struct inode *new_inode = d_inode(new_dentry);
2035         struct dentry *dentry = NULL, *rehash = NULL;
2036         struct rpc_task *task;
2037         int error = -EBUSY;
2038 
2039         if (flags)
2040                 return -EINVAL;
2041 
2042         dfprintk(VFS, "NFS: rename(%pd2 -> %pd2, ct=%d)\n",
2043                  old_dentry, new_dentry,
2044                  d_count(new_dentry));
2045 
2046         trace_nfs_rename_enter(old_dir, old_dentry, new_dir, new_dentry);
2047         /*
2048          * For non-directories, check whether the target is busy and if so,
2049          * make a copy of the dentry and then do a silly-rename. If the
2050          * silly-rename succeeds, the copied dentry is hashed and becomes
2051          * the new target.
2052          */
2053         if (new_inode && !S_ISDIR(new_inode->i_mode)) {
2054                 /*
2055                  * To prevent any new references to the target during the
2056                  * rename, we unhash the dentry in advance.
2057                  */
2058                 if (!d_unhashed(new_dentry)) {
2059                         d_drop(new_dentry);
2060                         rehash = new_dentry;
2061                 }
2062 
2063                 if (d_count(new_dentry) > 2) {
2064                         int err;
2065 
2066                         /* copy the target dentry's name */
2067                         dentry = d_alloc(new_dentry->d_parent,
2068                                          &new_dentry->d_name);
2069                         if (!dentry)
2070                                 goto out;
2071 
2072                         /* silly-rename the existing target ... */
2073                         err = nfs_sillyrename(new_dir, new_dentry);
2074                         if (err)
2075                                 goto out;
2076 
2077                         new_dentry = dentry;
2078                         rehash = NULL;
2079                         new_inode = NULL;
2080                 }
2081         }
2082 
2083         NFS_PROTO(old_inode)->return_delegation(old_inode);
2084         if (new_inode != NULL)
2085                 NFS_PROTO(new_inode)->return_delegation(new_inode);
2086 
2087         task = nfs_async_rename(old_dir, new_dir, old_dentry, new_dentry, NULL);
2088         if (IS_ERR(task)) {
2089                 error = PTR_ERR(task);
2090                 goto out;
2091         }
2092 
2093         error = rpc_wait_for_completion_task(task);
2094         if (error == 0)
2095                 error = task->tk_status;
2096         rpc_put_task(task);
2097         nfs_mark_for_revalidate(old_inode);
2098 out:
2099         if (rehash)
2100                 d_rehash(rehash);
2101         trace_nfs_rename_exit(old_dir, old_dentry,
2102                         new_dir, new_dentry, error);
2103         if (!error) {
2104                 if (new_inode != NULL)
2105                         nfs_drop_nlink(new_inode);
2106                 d_move(old_dentry, new_dentry);
2107                 nfs_set_verifier(new_dentry,
2108                                         nfs_save_change_attribute(new_dir));
2109         } else if (error == -ENOENT)
2110                 nfs_dentry_handle_enoent(old_dentry);
2111 
2112         /* new dentry created? */
2113         if (dentry)
2114                 dput(dentry);
2115         return error;
2116 }
2117 EXPORT_SYMBOL_GPL(nfs_rename);
2118 
2119 static DEFINE_SPINLOCK(nfs_access_lru_lock);
2120 static LIST_HEAD(nfs_access_lru_list);
2121 static atomic_long_t nfs_access_nr_entries;
2122 
2123 static unsigned long nfs_access_max_cachesize = ULONG_MAX;
2124 module_param(nfs_access_max_cachesize, ulong, 0644);
2125 MODULE_PARM_DESC(nfs_access_max_cachesize, "NFS access maximum total cache length");
2126 
2127 static void nfs_access_free_entry(struct nfs_access_entry *entry)
2128 {
2129         put_rpccred(entry->cred);
2130         kfree_rcu(entry, rcu_head);
2131         smp_mb__before_atomic();
2132         atomic_long_dec(&nfs_access_nr_entries);
2133         smp_mb__after_atomic();
2134 }
2135 
2136 static void nfs_access_free_list(struct list_head *head)
2137 {
2138         struct nfs_access_entry *cache;
2139 
2140         while (!list_empty(head)) {
2141                 cache = list_entry(head->next, struct nfs_access_entry, lru);
2142                 list_del(&cache->lru);
2143                 nfs_access_free_entry(cache);
2144         }
2145 }
2146 
2147 static unsigned long
2148 nfs_do_access_cache_scan(unsigned int nr_to_scan)
2149 {
2150         LIST_HEAD(head);
2151         struct nfs_inode *nfsi, *next;
2152         struct nfs_access_entry *cache;
2153         long freed = 0;
2154 
2155         spin_lock(&nfs_access_lru_lock);
2156         list_for_each_entry_safe(nfsi, next, &nfs_access_lru_list, access_cache_inode_lru) {
2157                 struct inode *inode;
2158 
2159                 if (nr_to_scan-- == 0)
2160                         break;
2161                 inode = &nfsi->vfs_inode;
2162                 spin_lock(&inode->i_lock);
2163                 if (list_empty(&nfsi->access_cache_entry_lru))
2164                         goto remove_lru_entry;
2165                 cache = list_entry(nfsi->access_cache_entry_lru.next,
2166                                 struct nfs_access_entry, lru);
2167                 list_move(&cache->lru, &head);
2168                 rb_erase(&cache->rb_node, &nfsi->access_cache);
2169                 freed++;
2170                 if (!list_empty(&nfsi->access_cache_entry_lru))
2171                         list_move_tail(&nfsi->access_cache_inode_lru,
2172                                         &nfs_access_lru_list);
2173                 else {
2174 remove_lru_entry:
2175                         list_del_init(&nfsi->access_cache_inode_lru);
2176                         smp_mb__before_atomic();
2177                         clear_bit(NFS_INO_ACL_LRU_SET, &nfsi->flags);
2178                         smp_mb__after_atomic();
2179                 }
2180                 spin_unlock(&inode->i_lock);
2181         }
2182         spin_unlock(&nfs_access_lru_lock);
2183         nfs_access_free_list(&head);
2184         return freed;
2185 }
2186 
2187 unsigned long
2188 nfs_access_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
2189 {
2190         int nr_to_scan = sc->nr_to_scan;
2191         gfp_t gfp_mask = sc->gfp_mask;
2192 
2193         if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
2194                 return SHRINK_STOP;
2195         return nfs_do_access_cache_scan(nr_to_scan);
2196 }
2197 
2198 
2199 unsigned long
2200 nfs_access_cache_count(struct shrinker *shrink, struct shrink_control *sc)
2201 {
2202         return vfs_pressure_ratio(atomic_long_read(&nfs_access_nr_entries));
2203 }
2204 
2205 static void
2206 nfs_access_cache_enforce_limit(void)
2207 {
2208         long nr_entries = atomic_long_read(&nfs_access_nr_entries);
2209         unsigned long diff;
2210         unsigned int nr_to_scan;
2211 
2212         if (nr_entries < 0 || nr_entries <= nfs_access_max_cachesize)
2213                 return;
2214         nr_to_scan = 100;
2215         diff = nr_entries - nfs_access_max_cachesize;
2216         if (diff < nr_to_scan)
2217                 nr_to_scan = diff;
2218         nfs_do_access_cache_scan(nr_to_scan);
2219 }
2220 
2221 static void __nfs_access_zap_cache(struct nfs_inode *nfsi, struct list_head *head)
2222 {
2223         struct rb_root *root_node = &nfsi->access_cache;
2224         struct rb_node *n;
2225         struct nfs_access_entry *entry;
2226 
2227         /* Unhook entries from the cache */
2228         while ((n = rb_first(root_node)) != NULL) {
2229                 entry = rb_entry(n, struct nfs_access_entry, rb_node);
2230                 rb_erase(n, root_node);
2231                 list_move(&entry->lru, head);
2232         }
2233         nfsi->cache_validity &= ~NFS_INO_INVALID_ACCESS;
2234 }
2235 
2236 void nfs_access_zap_cache(struct inode *inode)
2237 {
2238         LIST_HEAD(head);
2239 
2240         if (test_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags) == 0)
2241                 return;
2242         /* Remove from global LRU init */
2243         spin_lock(&nfs_access_lru_lock);
2244         if (test_and_clear_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags))
2245                 list_del_init(&NFS_I(inode)->access_cache_inode_lru);
2246 
2247         spin_lock(&inode->i_lock);
2248         __nfs_access_zap_cache(NFS_I(inode), &head);
2249         spin_unlock(&inode->i_lock);
2250         spin_unlock(&nfs_access_lru_lock);
2251         nfs_access_free_list(&head);
2252 }
2253 EXPORT_SYMBOL_GPL(nfs_access_zap_cache);
2254 
2255 static struct nfs_access_entry *nfs_access_search_rbtree(struct inode *inode, struct rpc_cred *cred)
2256 {
2257         struct rb_node *n = NFS_I(inode)->access_cache.rb_node;
2258         struct nfs_access_entry *entry;
2259 
2260         while (n != NULL) {
2261                 entry = rb_entry(n, struct nfs_access_entry, rb_node);
2262 
2263                 if (cred < entry->cred)
2264                         n = n->rb_left;
2265                 else if (cred > entry->cred)
2266                         n = n->rb_right;
2267                 else
2268                         return entry;
2269         }
2270         return NULL;
2271 }
2272 
2273 static int nfs_access_get_cached(struct inode *inode, struct rpc_cred *cred, struct nfs_access_entry *res, bool may_block)
2274 {
2275         struct nfs_inode *nfsi = NFS_I(inode);
2276         struct nfs_access_entry *cache;
2277         bool retry = true;
2278         int err;
2279 
2280         spin_lock(&inode->i_lock);
2281         for(;;) {
2282                 if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
2283                         goto out_zap;
2284                 cache = nfs_access_search_rbtree(inode, cred);
2285                 err = -ENOENT;
2286                 if (cache == NULL)
2287                         goto out;
2288                 /* Found an entry, is our attribute cache valid? */
2289                 if (!nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS))
2290                         break;
2291                 err = -ECHILD;
2292                 if (!may_block)
2293                         goto out;
2294                 if (!retry)
2295                         goto out_zap;
2296                 spin_unlock(&inode->i_lock);
2297                 err = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
2298                 if (err)
2299                         return err;
2300                 spin_lock(&inode->i_lock);
2301                 retry = false;
2302         }
2303         res->jiffies = cache->jiffies;
2304         res->cred = cache->cred;
2305         res->mask = cache->mask;
2306         list_move_tail(&cache->lru, &nfsi->access_cache_entry_lru);
2307         err = 0;
2308 out:
2309         spin_unlock(&inode->i_lock);
2310         return err;
2311 out_zap:
2312         spin_unlock(&inode->i_lock);
2313         nfs_access_zap_cache(inode);
2314         return -ENOENT;
2315 }
2316 
2317 static int nfs_access_get_cached_rcu(struct inode *inode, struct rpc_cred *cred, struct nfs_access_entry *res)
2318 {
2319         /* Only check the most recently returned cache entry,
2320          * but do it without locking.
2321          */
2322         struct nfs_inode *nfsi = NFS_I(inode);
2323         struct nfs_access_entry *cache;
2324         int err = -ECHILD;
2325         struct list_head *lh;
2326 
2327         rcu_read_lock();
2328         if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
2329                 goto out;
2330         lh = rcu_dereference(nfsi->access_cache_entry_lru.prev);
2331         cache = list_entry(lh, struct nfs_access_entry, lru);
2332         if (lh == &nfsi->access_cache_entry_lru ||
2333             cred != cache->cred)
2334                 cache = NULL;
2335         if (cache == NULL)
2336                 goto out;
2337         if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS))
2338                 goto out;
2339         res->jiffies = cache->jiffies;
2340         res->cred = cache->cred;
2341         res->mask = cache->mask;
2342         err = 0;
2343 out:
2344         rcu_read_unlock();
2345         return err;
2346 }
2347 
2348 static void nfs_access_add_rbtree(struct inode *inode, struct nfs_access_entry *set)
2349 {
2350         struct nfs_inode *nfsi = NFS_I(inode);
2351         struct rb_root *root_node = &nfsi->access_cache;
2352         struct rb_node **p = &root_node->rb_node;
2353         struct rb_node *parent = NULL;
2354         struct nfs_access_entry *entry;
2355 
2356         spin_lock(&inode->i_lock);
2357         while (*p != NULL) {
2358                 parent = *p;
2359                 entry = rb_entry(parent, struct nfs_access_entry, rb_node);
2360 
2361                 if (set->cred < entry->cred)
2362                         p = &parent->rb_left;
2363                 else if (set->cred > entry->cred)
2364                         p = &parent->rb_right;
2365                 else
2366                         goto found;
2367         }
2368         rb_link_node(&set->rb_node, parent, p);
2369         rb_insert_color(&set->rb_node, root_node);
2370         list_add_tail(&set->lru, &nfsi->access_cache_entry_lru);
2371         spin_unlock(&inode->i_lock);
2372         return;
2373 found:
2374         rb_replace_node(parent, &set->rb_node, root_node);
2375         list_add_tail(&set->lru, &nfsi->access_cache_entry_lru);
2376         list_del(&entry->lru);
2377         spin_unlock(&inode->i_lock);
2378         nfs_access_free_entry(entry);
2379 }
2380 
2381 void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set)
2382 {
2383         struct nfs_access_entry *cache = kmalloc(sizeof(*cache), GFP_KERNEL);
2384         if (cache == NULL)
2385                 return;
2386         RB_CLEAR_NODE(&cache->rb_node);
2387         cache->jiffies = set->jiffies;
2388         cache->cred = get_rpccred(set->cred);
2389         cache->mask = set->mask;
2390 
2391         /* The above field assignments must be visible
2392          * before this item appears on the lru.  We cannot easily
2393          * use rcu_assign_pointer, so just force the memory barrier.
2394          */
2395         smp_wmb();
2396         nfs_access_add_rbtree(inode, cache);
2397 
2398         /* Update accounting */
2399         smp_mb__before_atomic();
2400         atomic_long_inc(&nfs_access_nr_entries);
2401         smp_mb__after_atomic();
2402 
2403         /* Add inode to global LRU list */
2404         if (!test_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags)) {
2405                 spin_lock(&nfs_access_lru_lock);
2406                 if (!test_and_set_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags))
2407                         list_add_tail(&NFS_I(inode)->access_cache_inode_lru,
2408                                         &nfs_access_lru_list);
2409                 spin_unlock(&nfs_access_lru_lock);
2410         }
2411         nfs_access_cache_enforce_limit();
2412 }
2413 EXPORT_SYMBOL_GPL(nfs_access_add_cache);
2414 
2415 void nfs_access_set_mask(struct nfs_access_entry *entry, u32 access_result)
2416 {
2417         entry->mask = 0;
2418         if (access_result & NFS4_ACCESS_READ)
2419                 entry->mask |= MAY_READ;
2420         if (access_result &
2421             (NFS4_ACCESS_MODIFY | NFS4_ACCESS_EXTEND | NFS4_ACCESS_DELETE))
2422                 entry->mask |= MAY_WRITE;
2423         if (access_result & (NFS4_ACCESS_LOOKUP|NFS4_ACCESS_EXECUTE))
2424                 entry->mask |= MAY_EXEC;
2425 }
2426 EXPORT_SYMBOL_GPL(nfs_access_set_mask);
2427 
2428 static int nfs_do_access(struct inode *inode, struct rpc_cred *cred, int mask)
2429 {
2430         struct nfs_access_entry cache;
2431         bool may_block = (mask & MAY_NOT_BLOCK) == 0;
2432         int status;
2433 
2434         trace_nfs_access_enter(inode);
2435 
2436         status = nfs_access_get_cached_rcu(inode, cred, &cache);
2437         if (status != 0)
2438                 status = nfs_access_get_cached(inode, cred, &cache, may_block);
2439         if (status == 0)
2440                 goto out_cached;
2441 
2442         status = -ECHILD;
2443         if (!may_block)
2444                 goto out;
2445 
2446         /* Be clever: ask server to check for all possible rights */
2447         cache.mask = MAY_EXEC | MAY_WRITE | MAY_READ;
2448         cache.cred = cred;
2449         cache.jiffies = jiffies;
2450         status = NFS_PROTO(inode)->access(inode, &cache);
2451         if (status != 0) {
2452                 if (status == -ESTALE) {
2453                         nfs_zap_caches(inode);
2454                         if (!S_ISDIR(inode->i_mode))
2455                                 set_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
2456                 }
2457                 goto out;
2458         }
2459         nfs_access_add_cache(inode, &cache);
2460 out_cached:
2461         if ((mask & ~cache.mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) != 0)
2462                 status = -EACCES;
2463 out:
2464         trace_nfs_access_exit(inode, status);
2465         return status;
2466 }
2467 
2468 static int nfs_open_permission_mask(int openflags)
2469 {
2470         int mask = 0;
2471 
2472         if (openflags & __FMODE_EXEC) {
2473                 /* ONLY check exec rights */
2474                 mask = MAY_EXEC;
2475         } else {
2476                 if ((openflags & O_ACCMODE) != O_WRONLY)
2477                         mask |= MAY_READ;
2478                 if ((openflags & O_ACCMODE) != O_RDONLY)
2479                         mask |= MAY_WRITE;
2480         }
2481 
2482         return mask;
2483 }
2484 
2485 int nfs_may_open(struct inode *inode, struct rpc_cred *cred, int openflags)
2486 {
2487         return nfs_do_access(inode, cred, nfs_open_permission_mask(openflags));
2488 }
2489 EXPORT_SYMBOL_GPL(nfs_may_open);
2490 
2491 static int nfs_execute_ok(struct inode *inode, int mask)
2492 {
2493         struct nfs_server *server = NFS_SERVER(inode);
2494         int ret = 0;
2495 
2496         if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS)) {
2497                 if (mask & MAY_NOT_BLOCK)
2498                         return -ECHILD;
2499                 ret = __nfs_revalidate_inode(server, inode);
2500         }
2501         if (ret == 0 && !execute_ok(inode))
2502                 ret = -EACCES;
2503         return ret;
2504 }
2505 
2506 int nfs_permission(struct inode *inode, int mask)
2507 {
2508         struct rpc_cred *cred;
2509         int res = 0;
2510 
2511         nfs_inc_stats(inode, NFSIOS_VFSACCESS);
2512 
2513         if ((mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
2514                 goto out;
2515         /* Is this sys_access() ? */
2516         if (mask & (MAY_ACCESS | MAY_CHDIR))
2517                 goto force_lookup;
2518 
2519         switch (inode->i_mode & S_IFMT) {
2520                 case S_IFLNK:
2521                         goto out;
2522                 case S_IFREG:
2523                         if ((mask & MAY_OPEN) &&
2524                            nfs_server_capable(inode, NFS_CAP_ATOMIC_OPEN))
2525                                 return 0;
2526                         break;
2527                 case S_IFDIR:
2528                         /*
2529                          * Optimize away all write operations, since the server
2530                          * will check permissions when we perform the op.
2531                          */
2532                         if ((mask & MAY_WRITE) && !(mask & MAY_READ))
2533                                 goto out;
2534         }
2535 
2536 force_lookup:
2537         if (!NFS_PROTO(inode)->access)
2538                 goto out_notsup;
2539 
2540         /* Always try fast lookups first */
2541         rcu_read_lock();
2542         cred = rpc_lookup_cred_nonblock();
2543         if (!IS_ERR(cred))
2544                 res = nfs_do_access(inode, cred, mask|MAY_NOT_BLOCK);
2545         else
2546                 res = PTR_ERR(cred);
2547         rcu_read_unlock();
2548         if (res == -ECHILD && !(mask & MAY_NOT_BLOCK)) {
2549                 /* Fast lookup failed, try the slow way */
2550                 cred = rpc_lookup_cred();
2551                 if (!IS_ERR(cred)) {
2552                         res = nfs_do_access(inode, cred, mask);
2553                         put_rpccred(cred);
2554                 } else
2555                         res = PTR_ERR(cred);
2556         }
2557 out:
2558         if (!res && (mask & MAY_EXEC))
2559                 res = nfs_execute_ok(inode, mask);
2560 
2561         dfprintk(VFS, "NFS: permission(%s/%lu), mask=0x%x, res=%d\n",
2562                 inode->i_sb->s_id, inode->i_ino, mask, res);
2563         return res;
2564 out_notsup:
2565         if (mask & MAY_NOT_BLOCK)
2566                 return -ECHILD;
2567 
2568         res = nfs_revalidate_inode(NFS_SERVER(inode), inode);
2569         if (res == 0)
2570                 res = generic_permission(inode, mask);
2571         goto out;
2572 }
2573 EXPORT_SYMBOL_GPL(nfs_permission);
2574 
2575 /*
2576  * Local variables:
2577  *  version-control: t
2578  *  kept-new-versions: 5
2579  * End:
2580  */
2581 

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