fs/nfs/dir.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/fs/nfs/dir.c
   4  *
   5  *  Copyright (C) 1992  Rick Sladkey
   6  *
   7  *  nfs directory handling functions
   8  *
   9  * 10 Apr 1996  Added silly rename for unlink   --okir
  10  * 28 Sep 1996  Improved directory cache --okir
  11  * 23 Aug 1997  Claus Heine claus@momo.math.rwth-aachen.de
  12  *              Re-implemented silly rename for unlink, newly implemented
  13  *              silly rename for nfs_rename() following the suggestions
  14  *              of Olaf Kirch (okir) found in this file.
  15  *              Following Linus comments on my original hack, this version
  16  *              depends only on the dcache stuff and doesn't touch the inode
  17  *              layer (iput() and friends).
  18  *  6 Jun 1999  Cache readdir lookups in the page cache. -DaveM
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/time.h>
  23 #include <linux/errno.h>
  24 #include <linux/stat.h>
  25 #include <linux/fcntl.h>
  26 #include <linux/string.h>
  27 #include <linux/kernel.h>
  28 #include <linux/slab.h>
  29 #include <linux/mm.h>
  30 #include <linux/sunrpc/clnt.h>
  31 #include <linux/nfs_fs.h>
  32 #include <linux/nfs_mount.h>
  33 #include <linux/pagemap.h>
  34 #include <linux/pagevec.h>
  35 #include <linux/namei.h>
  36 #include <linux/mount.h>
  37 #include <linux/swap.h>
  38 #include <linux/sched.h>
  39 #include <linux/kmemleak.h>
  40 #include <linux/xattr.h>
  41
  42 #include "delegation.h"
  43 #include "iostat.h"
  44 #include "internal.h"
  45 #include "fscache.h"
  46
  47 #include "nfstrace.h"
  48
  49 /* #define NFS_DEBUG_VERBOSE 1 */
  50
  51 static int nfs_opendir(struct inode *, struct file *);
  52 static int nfs_closedir(struct inode *, struct file *);
  53 static int nfs_readdir(struct file *, struct dir_context *);
  54 static int nfs_fsync_dir(struct file *, loff_t, loff_t, int);
  55 static loff_t nfs_llseek_dir(struct file *, loff_t, int);
  56 static void nfs_readdir_clear_array(struct page*);
  57
  58 const struct file_operations nfs_dir_operations = {
  59         .llseek         = nfs_llseek_dir,
  60         .read           = generic_read_dir,
  61         .iterate_shared = nfs_readdir,
  62         .open           = nfs_opendir,
  63         .release        = nfs_closedir,
  64         .fsync          = nfs_fsync_dir,
  65 };
  66
  67 const struct address_space_operations nfs_dir_aops = {
  68         .freepage = nfs_readdir_clear_array,
  69 };
  70
  71 static struct nfs_open_dir_context *alloc_nfs_open_dir_context(struct inode *dir)
  72 {
  73         struct nfs_inode *nfsi = NFS_I(dir);
  74         struct nfs_open_dir_context *ctx;
  75         ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
  76         if (ctx != NULL) {
  77                 ctx->duped = 0;
  78                 ctx->attr_gencount = nfsi->attr_gencount;
  79                 ctx->dir_cookie = 0;
  80                 ctx->dup_cookie = 0;
  81                 spin_lock(&dir->i_lock);
  82                 if (list_empty(&nfsi->open_files) &&
  83                     (nfsi->cache_validity & NFS_INO_DATA_INVAL_DEFER))
  84                         nfs_set_cache_invalid(dir,
  85                                               NFS_INO_INVALID_DATA |
  86                                                       NFS_INO_REVAL_FORCED);
  87                 list_add(&ctx->list, &nfsi->open_files);
  88                 spin_unlock(&dir->i_lock);
  89                 return ctx;
  90         }
  91         return  ERR_PTR(-ENOMEM);
  92 }
  93
  94 static void put_nfs_open_dir_context(struct inode *dir, struct nfs_open_dir_context *ctx)
  95 {
  96         spin_lock(&dir->i_lock);
  97         list_del(&ctx->list);
  98         spin_unlock(&dir->i_lock);
  99         kfree(ctx);
 100 }
 101
 102 /*
 103  * Open file
 104  */
 105 static int
 106 nfs_opendir(struct inode *inode, struct file *filp)
 107 {
 108         int res = 0;
 109         struct nfs_open_dir_context *ctx;
 110
 111         dfprintk(FILE, "NFS: open dir(%pD2)\n", filp);
 112
 113         nfs_inc_stats(inode, NFSIOS_VFSOPEN);
 114
 115         ctx = alloc_nfs_open_dir_context(inode);
 116         if (IS_ERR(ctx)) {
 117                 res = PTR_ERR(ctx);
 118                 goto out;
 119         }
 120         filp->private_data = ctx;
 121 out:
 122         return res;
 123 }
 124
 125 static int
 126 nfs_closedir(struct inode *inode, struct file *filp)
 127 {
 128         put_nfs_open_dir_context(file_inode(filp), filp->private_data);
 129         return 0;
 130 }
 131
 132 struct nfs_cache_array_entry {
 133         u64 cookie;
 134         u64 ino;
 135         const char *name;
 136         unsigned int name_len;
 137         unsigned char d_type;
 138 };
 139
 140 struct nfs_cache_array {
 141         u64 last_cookie;
 142         unsigned int size;
 143         unsigned char page_full : 1,
 144                       page_is_eof : 1,
 145                       cookies_are_ordered : 1;
 146         struct nfs_cache_array_entry array[];
 147 };
 148
 149 struct nfs_readdir_descriptor {
 150         struct file     *file;
 151         struct page     *page;
 152         struct dir_context *ctx;
 153         pgoff_t         page_index;
 154         u64             dir_cookie;
 155         u64             last_cookie;
 156         u64             dup_cookie;
 157         loff_t          current_index;
 158         loff_t          prev_index;
 159
 160         __be32          verf[NFS_DIR_VERIFIER_SIZE];
 161         unsigned long   dir_verifier;
 162         unsigned long   timestamp;
 163         unsigned long   gencount;
 164         unsigned long   attr_gencount;
 165         unsigned int    cache_entry_index;
 166         signed char duped;
 167         bool plus;
 168         bool eof;
 169 };
 170
 171 static void nfs_readdir_array_init(struct nfs_cache_array *array)
 172 {
 173         memset(array, 0, sizeof(struct nfs_cache_array));
 174 }
 175
 176 static void nfs_readdir_page_init_array(struct page *page, u64 last_cookie)
 177 {
 178         struct nfs_cache_array *array;
 179
 180         array = kmap_atomic(page);
 181         nfs_readdir_array_init(array);
 182         array->last_cookie = last_cookie;
 183         array->cookies_are_ordered = 1;
 184         kunmap_atomic(array);
 185 }
 186
 187 /*
 188  * we are freeing strings created by nfs_add_to_readdir_array()
 189  */
 190 static
 191 void nfs_readdir_clear_array(struct page *page)
 192 {
 193         struct nfs_cache_array *array;
 194         int i;
 195
 196         array = kmap_atomic(page);
 197         for (i = 0; i < array->size; i++)
 198                 kfree(array->array[i].name);
 199         nfs_readdir_array_init(array);
 200         kunmap_atomic(array);
 201 }
 202
 203 static struct page *
 204 nfs_readdir_page_array_alloc(u64 last_cookie, gfp_t gfp_flags)
 205 {
 206         struct page *page = alloc_page(gfp_flags);
 207         if (page)
 208                 nfs_readdir_page_init_array(page, last_cookie);
 209         return page;
 210 }
 211
 212 static void nfs_readdir_page_array_free(struct page *page)
 213 {
 214         if (page) {
 215                 nfs_readdir_clear_array(page);
 216                 put_page(page);
 217         }
 218 }
 219
 220 static void nfs_readdir_array_set_eof(struct nfs_cache_array *array)
 221 {
 222         array->page_is_eof = 1;
 223         array->page_full = 1;
 224 }
 225
 226 static bool nfs_readdir_array_is_full(struct nfs_cache_array *array)
 227 {
 228         return array->page_full;
 229 }
 230
 231 /*
 232  * the caller is responsible for freeing qstr.name
 233  * when called by nfs_readdir_add_to_array, the strings will be freed in
 234  * nfs_clear_readdir_array()
 235  */
 236 static const char *nfs_readdir_copy_name(const char *name, unsigned int len)
 237 {
 238         const char *ret = kmemdup_nul(name, len, GFP_KERNEL);
 239
 240         /*
 241          * Avoid a kmemleak false positive. The pointer to the name is stored
 242          * in a page cache page which kmemleak does not scan.
 243          */
 244         if (ret != NULL)
 245                 kmemleak_not_leak(ret);
 246         return ret;
 247 }
 248
 249 /*
 250  * Check that the next array entry lies entirely within the page bounds
 251  */
 252 static int nfs_readdir_array_can_expand(struct nfs_cache_array *array)
 253 {
 254         struct nfs_cache_array_entry *cache_entry;
 255
 256         if (array->page_full)
 257                 return -ENOSPC;
 258         cache_entry = &array->array[array->size + 1];
 259         if ((char *)cache_entry - (char *)array > PAGE_SIZE) {
 260                 array->page_full = 1;
 261                 return -ENOSPC;
 262         }
 263         return 0;
 264 }
 265
 266 static
 267 int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
 268 {
 269         struct nfs_cache_array *array;
 270         struct nfs_cache_array_entry *cache_entry;
 271         const char *name;
 272         int ret;
 273
 274         name = nfs_readdir_copy_name(entry->name, entry->len);
 275         if (!name)
 276                 return -ENOMEM;
 277
 278         array = kmap_atomic(page);
 279         ret = nfs_readdir_array_can_expand(array);
 280         if (ret) {
 281                 kfree(name);
 282                 goto out;
 283         }
 284
 285         cache_entry = &array->array[array->size];
 286         cache_entry->cookie = entry->prev_cookie;
 287         cache_entry->ino = entry->ino;
 288         cache_entry->d_type = entry->d_type;
 289         cache_entry->name_len = entry->len;
 290         cache_entry->name = name;
 291         array->last_cookie = entry->cookie;
 292         if (array->last_cookie <= cache_entry->cookie)
 293                 array->cookies_are_ordered = 0;
 294         array->size++;
 295         if (entry->eof != 0)
 296                 nfs_readdir_array_set_eof(array);
 297 out:
 298         kunmap_atomic(array);
 299         return ret;
 300 }
 301
 302 static struct page *nfs_readdir_page_get_locked(struct address_space *mapping,
 303                                                 pgoff_t index, u64 last_cookie)
 304 {
 305         struct page *page;
 306
 307         page = grab_cache_page(mapping, index);
 308         if (page && !PageUptodate(page)) {
 309                 nfs_readdir_page_init_array(page, last_cookie);
 310                 if (invalidate_inode_pages2_range(mapping, index + 1, -1) < 0)
 311                         nfs_zap_mapping(mapping->host, mapping);
 312                 SetPageUptodate(page);
 313         }
 314
 315         return page;
 316 }
 317
 318 static u64 nfs_readdir_page_last_cookie(struct page *page)
 319 {
 320         struct nfs_cache_array *array;
 321         u64 ret;
 322
 323         array = kmap_atomic(page);
 324         ret = array->last_cookie;
 325         kunmap_atomic(array);
 326         return ret;
 327 }
 328
 329 static bool nfs_readdir_page_needs_filling(struct page *page)
 330 {
 331         struct nfs_cache_array *array;
 332         bool ret;
 333
 334         array = kmap_atomic(page);
 335         ret = !nfs_readdir_array_is_full(array);
 336         kunmap_atomic(array);
 337         return ret;
 338 }
 339
 340 static void nfs_readdir_page_set_eof(struct page *page)
 341 {
 342         struct nfs_cache_array *array;
 343
 344         array = kmap_atomic(page);
 345         nfs_readdir_array_set_eof(array);
 346         kunmap_atomic(array);
 347 }
 348
 349 static void nfs_readdir_page_unlock_and_put(struct page *page)
 350 {
 351         unlock_page(page);
 352         put_page(page);
 353 }
 354
 355 static struct page *nfs_readdir_page_get_next(struct address_space *mapping,
 356                                               pgoff_t index, u64 cookie)
 357 {
 358         struct page *page;
 359
 360         page = nfs_readdir_page_get_locked(mapping, index, cookie);
 361         if (page) {
 362                 if (nfs_readdir_page_last_cookie(page) == cookie)
 363                         return page;
 364                 nfs_readdir_page_unlock_and_put(page);
 365         }
 366         return NULL;
 367 }
 368
 369 static inline
 370 int is_32bit_api(void)
 371 {
 372 #ifdef CONFIG_COMPAT
 373         return in_compat_syscall();
 374 #else
 375         return (BITS_PER_LONG == 32);
 376 #endif
 377 }
 378
 379 static
 380 bool nfs_readdir_use_cookie(const struct file *filp)
 381 {
 382         if ((filp->f_mode & FMODE_32BITHASH) ||
 383             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 384                 return false;
 385         return true;
 386 }
 387
 388 static int nfs_readdir_search_for_pos(struct nfs_cache_array *array,
 389                                       struct nfs_readdir_descriptor *desc)
 390 {
 391         loff_t diff = desc->ctx->pos - desc->current_index;
 392         unsigned int index;
 393
 394         if (diff < 0)
 395                 goto out_eof;
 396         if (diff >= array->size) {
 397                 if (array->page_is_eof)
 398                         goto out_eof;
 399                 return -EAGAIN;
 400         }
 401
 402         index = (unsigned int)diff;
 403         desc->dir_cookie = array->array[index].cookie;
 404         desc->cache_entry_index = index;
 405         return 0;
 406 out_eof:
 407         desc->eof = true;
 408         return -EBADCOOKIE;
 409 }
 410
 411 static bool
 412 nfs_readdir_inode_mapping_valid(struct nfs_inode *nfsi)
 413 {
 414         if (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))
 415                 return false;
 416         smp_rmb();
 417         return !test_bit(NFS_INO_INVALIDATING, &nfsi->flags);
 418 }
 419
 420 static bool nfs_readdir_array_cookie_in_range(struct nfs_cache_array *array,
 421                                               u64 cookie)
 422 {
 423         if (!array->cookies_are_ordered)
 424                 return true;
 425         /* Optimisation for monotonically increasing cookies */
 426         if (cookie >= array->last_cookie)
 427                 return false;
 428         if (array->size && cookie < array->array[0].cookie)
 429                 return false;
 430         return true;
 431 }
 432
 433 static int nfs_readdir_search_for_cookie(struct nfs_cache_array *array,
 434                                          struct nfs_readdir_descriptor *desc)
 435 {
 436         int i;
 437         loff_t new_pos;
 438         int status = -EAGAIN;
 439
 440         if (!nfs_readdir_array_cookie_in_range(array, desc->dir_cookie))
 441                 goto check_eof;
 442
 443         for (i = 0; i < array->size; i++) {
 444                 if (array->array[i].cookie == desc->dir_cookie) {
 445                         struct nfs_inode *nfsi = NFS_I(file_inode(desc->file));
 446
 447                         new_pos = desc->current_index + i;
 448                         if (desc->attr_gencount != nfsi->attr_gencount ||
 449                             !nfs_readdir_inode_mapping_valid(nfsi)) {
 450                                 desc->duped = 0;
 451                                 desc->attr_gencount = nfsi->attr_gencount;
 452                         } else if (new_pos < desc->prev_index) {
 453                                 if (desc->duped > 0
 454                                     && desc->dup_cookie == desc->dir_cookie) {
 455                                         if (printk_ratelimit()) {
 456                                                 pr_notice("NFS: directory %pD2 contains a readdir loop."
 457                                                                 "Please contact your server vendor.  "
 458                                                                 "The file: %s has duplicate cookie %llu\n",
 459                                                                 desc->file, array->array[i].name, desc->dir_cookie);
 460                                         }
 461                                         status = -ELOOP;
 462                                         goto out;
 463                                 }
 464                                 desc->dup_cookie = desc->dir_cookie;
 465                                 desc->duped = -1;
 466                         }
 467                         if (nfs_readdir_use_cookie(desc->file))
 468                                 desc->ctx->pos = desc->dir_cookie;
 469                         else
 470                                 desc->ctx->pos = new_pos;
 471                         desc->prev_index = new_pos;
 472                         desc->cache_entry_index = i;
 473                         return 0;
 474                 }
 475         }
 476 check_eof:
 477         if (array->page_is_eof) {
 478                 status = -EBADCOOKIE;
 479                 if (desc->dir_cookie == array->last_cookie)
 480                         desc->eof = true;
 481         }
 482 out:
 483         return status;
 484 }
 485
 486 static int nfs_readdir_search_array(struct nfs_readdir_descriptor *desc)
 487 {
 488         struct nfs_cache_array *array;
 489         int status;
 490
 491         array = kmap_atomic(desc->page);
 492
 493         if (desc->dir_cookie == 0)
 494                 status = nfs_readdir_search_for_pos(array, desc);
 495         else
 496                 status = nfs_readdir_search_for_cookie(array, desc);
 497
 498         if (status == -EAGAIN) {
 499                 desc->last_cookie = array->last_cookie;
 500                 desc->current_index += array->size;
 501                 desc->page_index++;
 502         }
 503         kunmap_atomic(array);
 504         return status;
 505 }
 506
 507 /* Fill a page with xdr information before transferring to the cache page */
 508 static int nfs_readdir_xdr_filler(struct nfs_readdir_descriptor *desc,
 509                                   __be32 *verf, u64 cookie,
 510                                   struct page **pages, size_t bufsize,
 511                                   __be32 *verf_res)
 512 {
 513         struct inode *inode = file_inode(desc->file);
 514         struct nfs_readdir_arg arg = {
 515                 .dentry = file_dentry(desc->file),
 516                 .cred = desc->file->f_cred,
 517                 .verf = verf,
 518                 .cookie = cookie,
 519                 .pages = pages,
 520                 .page_len = bufsize,
 521                 .plus = desc->plus,
 522         };
 523         struct nfs_readdir_res res = {
 524                 .verf = verf_res,
 525         };
 526         unsigned long   timestamp, gencount;
 527         int             error;
 528
 529  again:
 530         timestamp = jiffies;
 531         gencount = nfs_inc_attr_generation_counter();
 532         desc->dir_verifier = nfs_save_change_attribute(inode);
 533         error = NFS_PROTO(inode)->readdir(&arg, &res);
 534         if (error < 0) {
 535                 /* We requested READDIRPLUS, but the server doesn't grok it */
 536                 if (error == -ENOTSUPP && desc->plus) {
 537                         NFS_SERVER(inode)->caps &= ~NFS_CAP_READDIRPLUS;
 538                         clear_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(inode)->flags);
 539                         desc->plus = arg.plus = false;
 540                         goto again;
 541                 }
 542                 goto error;
 543         }
 544         desc->timestamp = timestamp;
 545         desc->gencount = gencount;
 546 error:
 547         return error;
 548 }
 549
 550 static int xdr_decode(struct nfs_readdir_descriptor *desc,
 551                       struct nfs_entry *entry, struct xdr_stream *xdr)
 552 {
 553         struct inode *inode = file_inode(desc->file);
 554         int error;
 555
 556         error = NFS_PROTO(inode)->decode_dirent(xdr, entry, desc->plus);
 557         if (error)
 558                 return error;
 559         entry->fattr->time_start = desc->timestamp;
 560         entry->fattr->gencount = desc->gencount;
 561         return 0;
 562 }
 563
 564 /* Match file and dirent using either filehandle or fileid
 565  * Note: caller is responsible for checking the fsid
 566  */
 567 static
 568 int nfs_same_file(struct dentry *dentry, struct nfs_entry *entry)
 569 {
 570         struct inode *inode;
 571         struct nfs_inode *nfsi;
 572
 573         if (d_really_is_negative(dentry))
 574                 return 0;
 575
 576         inode = d_inode(dentry);
 577         if (is_bad_inode(inode) || NFS_STALE(inode))
 578                 return 0;
 579
 580         nfsi = NFS_I(inode);
 581         if (entry->fattr->fileid != nfsi->fileid)
 582                 return 0;
 583         if (entry->fh->size && nfs_compare_fh(entry->fh, &nfsi->fh) != 0)
 584                 return 0;
 585         return 1;
 586 }
 587
 588 static
 589 bool nfs_use_readdirplus(struct inode *dir, struct dir_context *ctx)
 590 {
 591         if (!nfs_server_capable(dir, NFS_CAP_READDIRPLUS))
 592                 return false;
 593         if (test_and_clear_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(dir)->flags))
 594                 return true;
 595         if (ctx->pos == 0)
 596                 return true;
 597         return false;
 598 }
 599
 600 /*
 601  * This function is called by the lookup and getattr code to request the
 602  * use of readdirplus to accelerate any future lookups in the same
 603  * directory.
 604  */
 605 void nfs_advise_use_readdirplus(struct inode *dir)
 606 {
 607         struct nfs_inode *nfsi = NFS_I(dir);
 608
 609         if (nfs_server_capable(dir, NFS_CAP_READDIRPLUS) &&
 610             !list_empty(&nfsi->open_files))
 611                 set_bit(NFS_INO_ADVISE_RDPLUS, &nfsi->flags);
 612 }
 613
 614 /*
 615  * This function is mainly for use by nfs_getattr().
 616  *
 617  * If this is an 'ls -l', we want to force use of readdirplus.
 618  * Do this by checking if there is an active file descriptor
 619  * and calling nfs_advise_use_readdirplus, then forcing a
 620  * cache flush.
 621  */
 622 void nfs_force_use_readdirplus(struct inode *dir)
 623 {
 624         struct nfs_inode *nfsi = NFS_I(dir);
 625
 626         if (nfs_server_capable(dir, NFS_CAP_READDIRPLUS) &&
 627             !list_empty(&nfsi->open_files)) {
 628                 set_bit(NFS_INO_ADVISE_RDPLUS, &nfsi->flags);
 629                 invalidate_mapping_pages(dir->i_mapping,
 630                         nfsi->page_index + 1, -1);
 631         }
 632 }
 633
 634 static
 635 void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry,
 636                 unsigned long dir_verifier)
 637 {
 638         struct qstr filename = QSTR_INIT(entry->name, entry->len);
 639         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
 640         struct dentry *dentry;
 641         struct dentry *alias;
 642         struct inode *inode;
 643         int status;
 644
 645         if (!(entry->fattr->valid & NFS_ATTR_FATTR_FILEID))
 646                 return;
 647         if (!(entry->fattr->valid & NFS_ATTR_FATTR_FSID))
 648                 return;
 649         if (filename.len == 0)
 650                 return;
 651         /* Validate that the name doesn't contain any illegal '\0' */
 652         if (strnlen(filename.name, filename.len) != filename.len)
 653                 return;
 654         /* ...or '/' */
 655         if (strnchr(filename.name, filename.len, '/'))
 656                 return;
 657         if (filename.name[0] == '.') {
 658                 if (filename.len == 1)
 659                         return;
 660                 if (filename.len == 2 && filename.name[1] == '.')
 661                         return;
 662         }
 663         filename.hash = full_name_hash(parent, filename.name, filename.len);
 664
 665         dentry = d_lookup(parent, &filename);
 666 again:
 667         if (!dentry) {
 668                 dentry = d_alloc_parallel(parent, &filename, &wq);
 669                 if (IS_ERR(dentry))
 670                         return;
 671         }
 672         if (!d_in_lookup(dentry)) {
 673                 /* Is there a mountpoint here? If so, just exit */
 674                 if (!nfs_fsid_equal(&NFS_SB(dentry->d_sb)->fsid,
 675                                         &entry->fattr->fsid))
 676                         goto out;
 677                 if (nfs_same_file(dentry, entry)) {
 678                         if (!entry->fh->size)
 679                                 goto out;
 680                         nfs_set_verifier(dentry, dir_verifier);
 681                         status = nfs_refresh_inode(d_inode(dentry), entry->fattr);
 682                         if (!status)
 683                                 nfs_setsecurity(d_inode(dentry), entry->fattr, entry->label);
 684                         goto out;
 685                 } else {
 686                         d_invalidate(dentry);
 687                         dput(dentry);
 688                         dentry = NULL;
 689                         goto again;
 690                 }
 691         }
 692         if (!entry->fh->size) {
 693                 d_lookup_done(dentry);
 694                 goto out;
 695         }
 696
 697         inode = nfs_fhget(dentry->d_sb, entry->fh, entry->fattr, entry->label);
 698         alias = d_splice_alias(inode, dentry);
 699         d_lookup_done(dentry);
 700         if (alias) {
 701                 if (IS_ERR(alias))
 702                         goto out;
 703                 dput(dentry);
 704                 dentry = alias;
 705         }
 706         nfs_set_verifier(dentry, dir_verifier);
 707 out:
 708         dput(dentry);
 709 }
 710
 711 /* Perform conversion from xdr to cache array */
 712 static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc,
 713                                    struct nfs_entry *entry,
 714                                    struct page **xdr_pages,
 715                                    unsigned int buflen,
 716                                    struct page **arrays,
 717                                    size_t narrays)
 718 {
 719         struct address_space *mapping = desc->file->f_mapping;
 720         struct xdr_stream stream;
 721         struct xdr_buf buf;
 722         struct page *scratch, *new, *page = *arrays;
 723         int status;
 724
 725         scratch = alloc_page(GFP_KERNEL);
 726         if (scratch == NULL)
 727                 return -ENOMEM;
 728
 729         xdr_init_decode_pages(&stream, &buf, xdr_pages, buflen);
 730         xdr_set_scratch_page(&stream, scratch);
 731
 732         do {
 733                 if (entry->label)
 734                         entry->label->len = NFS4_MAXLABELLEN;
 735
 736                 status = xdr_decode(desc, entry, &stream);
 737                 if (status != 0)
 738                         break;
 739
 740                 if (desc->plus)
 741                         nfs_prime_dcache(file_dentry(desc->file), entry,
 742                                         desc->dir_verifier);
 743
 744                 status = nfs_readdir_add_to_array(entry, page);
 745                 if (status != -ENOSPC)
 746                         continue;
 747
 748                 if (page->mapping != mapping) {
 749                         if (!--narrays)
 750                                 break;
 751                         new = nfs_readdir_page_array_alloc(entry->prev_cookie,
 752                                                            GFP_KERNEL);
 753                         if (!new)
 754                                 break;
 755                         arrays++;
 756                         *arrays = page = new;
 757                 } else {
 758                         new = nfs_readdir_page_get_next(mapping,
 759                                                         page->index + 1,
 760                                                         entry->prev_cookie);
 761                         if (!new)
 762                                 break;
 763                         if (page != *arrays)
 764                                 nfs_readdir_page_unlock_and_put(page);
 765                         page = new;
 766                 }
 767                 status = nfs_readdir_add_to_array(entry, page);
 768         } while (!status && !entry->eof);
 769
 770         switch (status) {
 771         case -EBADCOOKIE:
 772                 if (entry->eof) {
 773                         nfs_readdir_page_set_eof(page);
 774                         status = 0;
 775                 }
 776                 break;
 777         case -ENOSPC:
 778         case -EAGAIN:
 779                 status = 0;
 780                 break;
 781         }
 782
 783         if (page != *arrays)
 784                 nfs_readdir_page_unlock_and_put(page);
 785
 786         put_page(scratch);
 787         return status;
 788 }
 789
 790 static void nfs_readdir_free_pages(struct page **pages, size_t npages)
 791 {
 792         while (npages--)
 793                 put_page(pages[npages]);
 794         kfree(pages);
 795 }
 796
 797 /*
 798  * nfs_readdir_alloc_pages() will allocate pages that must be freed with a call
 799  * to nfs_readdir_free_pages()
 800  */
 801 static struct page **nfs_readdir_alloc_pages(size_t npages)
 802 {
 803         struct page **pages;
 804         size_t i;
 805
 806         pages = kmalloc_array(npages, sizeof(*pages), GFP_KERNEL);
 807         if (!pages)
 808                 return NULL;
 809         for (i = 0; i < npages; i++) {
 810                 struct page *page = alloc_page(GFP_KERNEL);
 811                 if (page == NULL)
 812                         goto out_freepages;
 813                 pages[i] = page;
 814         }
 815         return pages;
 816
 817 out_freepages:
 818         nfs_readdir_free_pages(pages, i);
 819         return NULL;
 820 }
 821
 822 static int nfs_readdir_xdr_to_array(struct nfs_readdir_descriptor *desc,
 823                                     __be32 *verf_arg, __be32 *verf_res,
 824                                     struct page **arrays, size_t narrays)
 825 {
 826         struct page **pages;
 827         struct page *page = *arrays;
 828         struct nfs_entry *entry;
 829         size_t array_size;
 830         struct inode *inode = file_inode(desc->file);
 831         size_t dtsize = NFS_SERVER(inode)->dtsize;
 832         int status = -ENOMEM;
 833
 834         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 835         if (!entry)
 836                 return -ENOMEM;
 837         entry->cookie = nfs_readdir_page_last_cookie(page);
 838         entry->fh = nfs_alloc_fhandle();
 839         entry->fattr = nfs_alloc_fattr();
 840         entry->server = NFS_SERVER(inode);
 841         if (entry->fh == NULL || entry->fattr == NULL)
 842                 goto out;
 843
 844         entry->label = nfs4_label_alloc(NFS_SERVER(inode), GFP_NOWAIT);
 845         if (IS_ERR(entry->label)) {
 846                 status = PTR_ERR(entry->label);
 847                 goto out;
 848         }
 849
 850         array_size = (dtsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
 851         pages = nfs_readdir_alloc_pages(array_size);
 852         if (!pages)
 853                 goto out_release_label;
 854
 855         do {
 856                 unsigned int pglen;
 857                 status = nfs_readdir_xdr_filler(desc, verf_arg, entry->cookie,
 858                                                 pages, dtsize,
 859                                                 verf_res);
 860                 if (status < 0)
 861                         break;
 862
 863                 pglen = status;
 864                 if (pglen == 0) {
 865                         nfs_readdir_page_set_eof(page);
 866                         break;
 867                 }
 868
 869                 verf_arg = verf_res;
 870
 871                 status = nfs_readdir_page_filler(desc, entry, pages, pglen,
 872                                                  arrays, narrays);
 873         } while (!status && nfs_readdir_page_needs_filling(page));
 874
 875         nfs_readdir_free_pages(pages, array_size);
 876 out_release_label:
 877         nfs4_label_free(entry->label);
 878 out:
 879         nfs_free_fattr(entry->fattr);
 880         nfs_free_fhandle(entry->fh);
 881         kfree(entry);
 882         return status;
 883 }
 884
 885 static void nfs_readdir_page_put(struct nfs_readdir_descriptor *desc)
 886 {
 887         put_page(desc->page);
 888         desc->page = NULL;
 889 }
 890
 891 static void
 892 nfs_readdir_page_unlock_and_put_cached(struct nfs_readdir_descriptor *desc)
 893 {
 894         unlock_page(desc->page);
 895         nfs_readdir_page_put(desc);
 896 }
 897
 898 static struct page *
 899 nfs_readdir_page_get_cached(struct nfs_readdir_descriptor *desc)
 900 {
 901         return nfs_readdir_page_get_locked(desc->file->f_mapping,
 902                                            desc->page_index,
 903                                            desc->last_cookie);
 904 }
 905
 906 /*
 907  * Returns 0 if desc->dir_cookie was found on page desc->page_index
 908  * and locks the page to prevent removal from the page cache.
 909  */
 910 static int find_and_lock_cache_page(struct nfs_readdir_descriptor *desc)
 911 {
 912         struct inode *inode = file_inode(desc->file);
 913         struct nfs_inode *nfsi = NFS_I(inode);
 914         __be32 verf[NFS_DIR_VERIFIER_SIZE];
 915         int res;
 916
 917         desc->page = nfs_readdir_page_get_cached(desc);
 918         if (!desc->page)
 919                 return -ENOMEM;
 920         if (nfs_readdir_page_needs_filling(desc->page)) {
 921                 res = nfs_readdir_xdr_to_array(desc, nfsi->cookieverf, verf,
 922                                                &desc->page, 1);
 923                 if (res < 0) {
 924                         nfs_readdir_page_unlock_and_put_cached(desc);
 925                         if (res == -EBADCOOKIE || res == -ENOTSYNC) {
 926                                 invalidate_inode_pages2(desc->file->f_mapping);
 927                                 desc->page_index = 0;
 928                                 return -EAGAIN;
 929                         }
 930                         return res;
 931                 }
 932                 /*
 933                  * Set the cookie verifier if the page cache was empty
 934                  */
 935                 if (desc->page_index == 0)
 936                         memcpy(nfsi->cookieverf, verf,
 937                                sizeof(nfsi->cookieverf));
 938         }
 939         res = nfs_readdir_search_array(desc);
 940         if (res == 0) {
 941                 nfsi->page_index = desc->page_index;
 942                 return 0;
 943         }
 944         nfs_readdir_page_unlock_and_put_cached(desc);
 945         return res;
 946 }
 947
 948 static bool nfs_readdir_dont_search_cache(struct nfs_readdir_descriptor *desc)
 949 {
 950         struct address_space *mapping = desc->file->f_mapping;
 951         struct inode *dir = file_inode(desc->file);
 952         unsigned int dtsize = NFS_SERVER(dir)->dtsize;
 953         loff_t size = i_size_read(dir);
 954
 955         /*
 956          * Default to uncached readdir if the page cache is empty, and
 957          * we're looking for a non-zero cookie in a large directory.
 958          */
 959         return desc->dir_cookie != 0 && mapping->nrpages == 0 && size > dtsize;
 960 }
 961
 962 /* Search for desc->dir_cookie from the beginning of the page cache */
 963 static int readdir_search_pagecache(struct nfs_readdir_descriptor *desc)
 964 {
 965         int res;
 966
 967         if (nfs_readdir_dont_search_cache(desc))
 968                 return -EBADCOOKIE;
 969
 970         do {
 971                 if (desc->page_index == 0) {
 972                         desc->current_index = 0;
 973                         desc->prev_index = 0;
 974                         desc->last_cookie = 0;
 975                 }
 976                 res = find_and_lock_cache_page(desc);
 977         } while (res == -EAGAIN);
 978         return res;
 979 }
 980
 981 /*
 982  * Once we've found the start of the dirent within a page: fill 'er up...
 983  */
 984 static void nfs_do_filldir(struct nfs_readdir_descriptor *desc,
 985                            const __be32 *verf)
 986 {
 987         struct file     *file = desc->file;
 988         struct nfs_cache_array *array;
 989         unsigned int i = 0;
 990
 991         array = kmap(desc->page);
 992         for (i = desc->cache_entry_index; i < array->size; i++) {
 993                 struct nfs_cache_array_entry *ent;
 994
 995                 ent = &array->array[i];
 996                 if (!dir_emit(desc->ctx, ent->name, ent->name_len,
 997                     nfs_compat_user_ino64(ent->ino), ent->d_type)) {
 998                         desc->eof = true;
 999                         break;
1000                 }
1001                 memcpy(desc->verf, verf, sizeof(desc->verf));
1002                 if (i < (array->size-1))
1003                         desc->dir_cookie = array->array[i+1].cookie;
1004                 else
1005                         desc->dir_cookie = array->last_cookie;
1006                 if (nfs_readdir_use_cookie(file))
1007                         desc->ctx->pos = desc->dir_cookie;
1008                 else
1009                         desc->ctx->pos++;
1010                 if (desc->duped != 0)
1011                         desc->duped = 1;
1012         }
1013         if (array->page_is_eof)
1014                 desc->eof = true;
1015
1016         kunmap(desc->page);
1017         dfprintk(DIRCACHE, "NFS: nfs_do_filldir() filling ended @ cookie %llu\n",
1018                         (unsigned long long)desc->dir_cookie);
1019 }
1020
1021 /*
1022  * If we cannot find a cookie in our cache, we suspect that this is
1023  * because it points to a deleted file, so we ask the server to return
1024  * whatever it thinks is the next entry. We then feed this to filldir.
1025  * If all goes well, we should then be able to find our way round the
1026  * cache on the next call to readdir_search_pagecache();
1027  *
1028  * NOTE: we cannot add the anonymous page to the pagecache because
1029  *       the data it contains might not be page aligned. Besides,
1030  *       we should already have a complete representation of the
1031  *       directory in the page cache by the time we get here.
1032  */
1033 static int uncached_readdir(struct nfs_readdir_descriptor *desc)
1034 {
1035         struct page     **arrays;
1036         size_t          i, sz = 512;
1037         __be32          verf[NFS_DIR_VERIFIER_SIZE];
1038         int             status = -ENOMEM;
1039
1040         dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie %llu\n",
1041                         (unsigned long long)desc->dir_cookie);
1042
1043         arrays = kcalloc(sz, sizeof(*arrays), GFP_KERNEL);
1044         if (!arrays)
1045                 goto out;
1046         arrays[0] = nfs_readdir_page_array_alloc(desc->dir_cookie, GFP_KERNEL);
1047         if (!arrays[0])
1048                 goto out;
1049
1050         desc->page_index = 0;
1051         desc->last_cookie = desc->dir_cookie;
1052         desc->duped = 0;
1053
1054         status = nfs_readdir_xdr_to_array(desc, desc->verf, verf, arrays, sz);
1055
1056         for (i = 0; !desc->eof && i < sz && arrays[i]; i++) {
1057                 desc->page = arrays[i];
1058                 nfs_do_filldir(desc, verf);
1059         }
1060         desc->page = NULL;
1061
1062
1063         for (i = 0; i < sz && arrays[i]; i++)
1064                 nfs_readdir_page_array_free(arrays[i]);
1065 out:
1066         kfree(arrays);
1067         dfprintk(DIRCACHE, "NFS: %s: returns %d\n", __func__, status);
1068         return status;
1069 }
1070
1071 /* The file offset position represents the dirent entry number.  A
1072    last cookie cache takes care of the common case of reading the
1073    whole directory.
1074  */
1075 static int nfs_readdir(struct file *file, struct dir_context *ctx)
1076 {
1077         struct dentry   *dentry = file_dentry(file);
1078         struct inode    *inode = d_inode(dentry);
1079         struct nfs_inode *nfsi = NFS_I(inode);
1080         struct nfs_open_dir_context *dir_ctx = file->private_data;
1081         struct nfs_readdir_descriptor *desc;
1082         int res;
1083
1084         dfprintk(FILE, "NFS: readdir(%pD2) starting at cookie %llu\n",
1085                         file, (long long)ctx->pos);
1086         nfs_inc_stats(inode, NFSIOS_VFSGETDENTS);
1087
1088         /*
1089          * ctx->pos points to the dirent entry number.
1090          * *desc->dir_cookie has the cookie for the next entry. We have
1091          * to either find the entry with the appropriate number or
1092          * revalidate the cookie.
1093          */
1094         if (ctx->pos == 0 || nfs_attribute_cache_expired(inode)) {
1095                 res = nfs_revalidate_mapping(inode, file->f_mapping);
1096                 if (res < 0)
1097                         goto out;
1098         }
1099
1100         res = -ENOMEM;
1101         desc = kzalloc(sizeof(*desc), GFP_KERNEL);
1102         if (!desc)
1103                 goto out;
1104         desc->file = file;
1105         desc->ctx = ctx;
1106         desc->plus = nfs_use_readdirplus(inode, ctx);
1107
1108         spin_lock(&file->f_lock);
1109         desc->dir_cookie = dir_ctx->dir_cookie;
1110         desc->dup_cookie = dir_ctx->dup_cookie;
1111         desc->duped = dir_ctx->duped;
1112         desc->attr_gencount = dir_ctx->attr_gencount;
1113         memcpy(desc->verf, dir_ctx->verf, sizeof(desc->verf));
1114         spin_unlock(&file->f_lock);
1115
1116         do {
1117                 res = readdir_search_pagecache(desc);
1118
1119                 if (res == -EBADCOOKIE) {
1120                         res = 0;
1121                         /* This means either end of directory */
1122                         if (desc->dir_cookie && !desc->eof) {
1123                                 /* Or that the server has 'lost' a cookie */
1124                                 res = uncached_readdir(desc);
1125                                 if (res == 0)
1126                                         continue;
1127                                 if (res == -EBADCOOKIE || res == -ENOTSYNC)
1128                                         res = 0;
1129                         }
1130                         break;
1131                 }
1132                 if (res == -ETOOSMALL && desc->plus) {
1133                         clear_bit(NFS_INO_ADVISE_RDPLUS, &nfsi->flags);
1134                         nfs_zap_caches(inode);
1135                         desc->page_index = 0;
1136                         desc->plus = false;
1137                         desc->eof = false;
1138                         continue;
1139                 }
1140                 if (res < 0)
1141                         break;
1142
1143                 nfs_do_filldir(desc, nfsi->cookieverf);
1144                 nfs_readdir_page_unlock_and_put_cached(desc);
1145         } while (!desc->eof);
1146
1147         spin_lock(&file->f_lock);
1148         dir_ctx->dir_cookie = desc->dir_cookie;
1149         dir_ctx->dup_cookie = desc->dup_cookie;
1150         dir_ctx->duped = desc->duped;
1151         dir_ctx->attr_gencount = desc->attr_gencount;
1152         memcpy(dir_ctx->verf, desc->verf, sizeof(dir_ctx->verf));
1153         spin_unlock(&file->f_lock);
1154
1155         kfree(desc);
1156
1157 out:
1158         dfprintk(FILE, "NFS: readdir(%pD2) returns %d\n", file, res);
1159         return res;
1160 }
1161
1162 static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence)
1163 {
1164         struct nfs_open_dir_context *dir_ctx = filp->private_data;
1165
1166         dfprintk(FILE, "NFS: llseek dir(%pD2, %lld, %d)\n",
1167                         filp, offset, whence);
1168
1169         switch (whence) {
1170         default:
1171                 return -EINVAL;
1172         case SEEK_SET:
1173                 if (offset < 0)
1174                         return -EINVAL;
1175                 spin_lock(&filp->f_lock);
1176                 break;
1177         case SEEK_CUR:
1178                 if (offset == 0)
1179                         return filp->f_pos;
1180                 spin_lock(&filp->f_lock);
1181                 offset += filp->f_pos;
1182                 if (offset < 0) {
1183                         spin_unlock(&filp->f_lock);
1184                         return -EINVAL;
1185                 }
1186         }
1187         if (offset != filp->f_pos) {
1188                 filp->f_pos = offset;
1189                 if (nfs_readdir_use_cookie(filp))
1190                         dir_ctx->dir_cookie = offset;
1191                 else
1192                         dir_ctx->dir_cookie = 0;
1193                 if (offset == 0)
1194                         memset(dir_ctx->verf, 0, sizeof(dir_ctx->verf));
1195                 dir_ctx->duped = 0;
1196         }
1197         spin_unlock(&filp->f_lock);
1198         return offset;
1199 }
1200
1201 /*
1202  * All directory operations under NFS are synchronous, so fsync()
1203  * is a dummy operation.
1204  */
1205 static int nfs_fsync_dir(struct file *filp, loff_t start, loff_t end,
1206                          int datasync)
1207 {
1208         dfprintk(FILE, "NFS: fsync dir(%pD2) datasync %d\n", filp, datasync);
1209
1210         nfs_inc_stats(file_inode(filp), NFSIOS_VFSFSYNC);
1211         return 0;
1212 }
1213
1214 /**
1215  * nfs_force_lookup_revalidate - Mark the directory as having changed
1216  * @dir: pointer to directory inode
1217  *
1218  * This forces the revalidation code in nfs_lookup_revalidate() to do a
1219  * full lookup on all child dentries of 'dir' whenever a change occurs
1220  * on the server that might have invalidated our dcache.
1221  *
1222  * Note that we reserve bit '0' as a tag to let us know when a dentry
1223  * was revalidated while holding a delegation on its inode.
1224  *
1225  * The caller should be holding dir->i_lock
1226  */
1227 void nfs_force_lookup_revalidate(struct inode *dir)
1228 {
1229         NFS_I(dir)->cache_change_attribute += 2;
1230 }
1231 EXPORT_SYMBOL_GPL(nfs_force_lookup_revalidate);
1232
1233 /**
1234  * nfs_verify_change_attribute - Detects NFS remote directory changes
1235  * @dir: pointer to parent directory inode
1236  * @verf: previously saved change attribute
1237  *
1238  * Return "false" if the verifiers doesn't match the change attribute.
1239  * This would usually indicate that the directory contents have changed on
1240  * the server, and that any dentries need revalidating.
1241  */
1242 static bool nfs_verify_change_attribute(struct inode *dir, unsigned long verf)
1243 {
1244         return (verf & ~1UL) == nfs_save_change_attribute(dir);
1245 }
1246
1247 static void nfs_set_verifier_delegated(unsigned long *verf)
1248 {
1249         *verf |= 1UL;
1250 }
1251
1252 #if IS_ENABLED(CONFIG_NFS_V4)
1253 static void nfs_unset_verifier_delegated(unsigned long *verf)
1254 {
1255         *verf &= ~1UL;
1256 }
1257 #endif /* IS_ENABLED(CONFIG_NFS_V4) */
1258
1259 static bool nfs_test_verifier_delegated(unsigned long verf)
1260 {
1261         return verf & 1;
1262 }
1263
1264 static bool nfs_verifier_is_delegated(struct dentry *dentry)
1265 {
1266         return nfs_test_verifier_delegated(dentry->d_time);
1267 }
1268
1269 static void nfs_set_verifier_locked(struct dentry *dentry, unsigned long verf)
1270 {
1271         struct inode *inode = d_inode(dentry);
1272
1273         if (!nfs_verifier_is_delegated(dentry) &&
1274             !nfs_verify_change_attribute(d_inode(dentry->d_parent), verf))
1275                 goto out;
1276         if (inode && NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))
1277                 nfs_set_verifier_delegated(&verf);
1278 out:
1279         dentry->d_time = verf;
1280 }
1281
1282 /**
1283  * nfs_set_verifier - save a parent directory verifier in the dentry
1284  * @dentry: pointer to dentry
1285  * @verf: verifier to save
1286  *
1287  * Saves the parent directory verifier in @dentry. If the inode has
1288  * a delegation, we also tag the dentry as having been revalidated
1289  * while holding a delegation so that we know we don't have to
1290  * look it up again after a directory change.
1291  */
1292 void nfs_set_verifier(struct dentry *dentry, unsigned long verf)
1293 {
1294
1295         spin_lock(&dentry->d_lock);
1296         nfs_set_verifier_locked(dentry, verf);
1297         spin_unlock(&dentry->d_lock);
1298 }
1299 EXPORT_SYMBOL_GPL(nfs_set_verifier);
1300
1301 #if IS_ENABLED(CONFIG_NFS_V4)
1302 /**
1303  * nfs_clear_verifier_delegated - clear the dir verifier delegation tag
1304  * @inode: pointer to inode
1305  *
1306  * Iterates through the dentries in the inode alias list and clears
1307  * the tag used to indicate that the dentry has been revalidated
1308  * while holding a delegation.
1309  * This function is intended for use when the delegation is being
1310  * returned or revoked.
1311  */
1312 void nfs_clear_verifier_delegated(struct inode *inode)
1313 {
1314         struct dentry *alias;
1315
1316         if (!inode)
1317                 return;
1318         spin_lock(&inode->i_lock);
1319         hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
1320                 spin_lock(&alias->d_lock);
1321                 nfs_unset_verifier_delegated(&alias->d_time);
1322                 spin_unlock(&alias->d_lock);
1323         }
1324         spin_unlock(&inode->i_lock);
1325 }
1326 EXPORT_SYMBOL_GPL(nfs_clear_verifier_delegated);
1327 #endif /* IS_ENABLED(CONFIG_NFS_V4) */
1328
1329 /*
1330  * A check for whether or not the parent directory has changed.
1331  * In the case it has, we assume that the dentries are untrustworthy
1332  * and may need to be looked up again.
1333  * If rcu_walk prevents us from performing a full check, return 0.
1334  */
1335 static int nfs_check_verifier(struct inode *dir, struct dentry *dentry,
1336                               int rcu_walk)
1337 {
1338         if (IS_ROOT(dentry))
1339                 return 1;
1340         if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
1341                 return 0;
1342         if (!nfs_verify_change_attribute(dir, dentry->d_time))
1343                 return 0;
1344         /* Revalidate nfsi->cache_change_attribute before we declare a match */
1345         if (nfs_mapping_need_revalidate_inode(dir)) {
1346                 if (rcu_walk)
1347                         return 0;
1348                 if (__nfs_revalidate_inode(NFS_SERVER(dir), dir) < 0)
1349                         return 0;
1350         }
1351         if (!nfs_verify_change_attribute(dir, dentry->d_time))
1352                 return 0;
1353         return 1;
1354 }
1355
1356 /*
1357  * Use intent information to check whether or not we're going to do
1358  * an O_EXCL create using this path component.
1359  */
1360 static int nfs_is_exclusive_create(struct inode *dir, unsigned int flags)
1361 {
1362         if (NFS_PROTO(dir)->version == 2)
1363                 return 0;
1364         return flags & LOOKUP_EXCL;
1365 }
1366
1367 /*
1368  * Inode and filehandle revalidation for lookups.
1369  *
1370  * We force revalidation in the cases where the VFS sets LOOKUP_REVAL,
1371  * or if the intent information indicates that we're about to open this
1372  * particular file and the "nocto" mount flag is not set.
1373  *
1374  */
1375 static
1376 int nfs_lookup_verify_inode(struct inode *inode, unsigned int flags)
1377 {
1378         struct nfs_server *server = NFS_SERVER(inode);
1379         int ret;
1380
1381         if (IS_AUTOMOUNT(inode))
1382                 return 0;
1383
1384         if (flags & LOOKUP_OPEN) {
1385                 switch (inode->i_mode & S_IFMT) {
1386                 case S_IFREG:
1387                         /* A NFSv4 OPEN will revalidate later */
1388                         if (server->caps & NFS_CAP_ATOMIC_OPEN)
1389                                 goto out;
1390                         fallthrough;
1391                 case S_IFDIR:
1392                         if (server->flags & NFS_MOUNT_NOCTO)
1393                                 break;
1394                         /* NFS close-to-open cache consistency validation */
1395                         goto out_force;
1396                 }
1397         }
1398
1399         /* VFS wants an on-the-wire revalidation */
1400         if (flags & LOOKUP_REVAL)
1401                 goto out_force;
1402 out:
1403         return (inode->i_nlink == 0) ? -ESTALE : 0;
1404 out_force:
1405         if (flags & LOOKUP_RCU)
1406                 return -ECHILD;
1407         ret = __nfs_revalidate_inode(server, inode);
1408         if (ret != 0)
1409                 return ret;
1410         goto out;
1411 }
1412
1413 static void nfs_mark_dir_for_revalidate(struct inode *inode)
1414 {
1415         spin_lock(&inode->i_lock);
1416         nfs_set_cache_invalid(inode, NFS_INO_REVAL_PAGECACHE);
1417         spin_unlock(&inode->i_lock);
1418 }
1419
1420 /*
1421  * We judge how long we want to trust negative
1422  * dentries by looking at the parent inode mtime.
1423  *
1424  * If parent mtime has changed, we revalidate, else we wait for a
1425  * period corresponding to the parent's attribute cache timeout value.
1426  *
1427  * If LOOKUP_RCU prevents us from performing a full check, return 1
1428  * suggesting a reval is needed.
1429  *
1430  * Note that when creating a new file, or looking up a rename target,
1431  * then it shouldn't be necessary to revalidate a negative dentry.
1432  */
1433 static inline
1434 int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry,
1435                        unsigned int flags)
1436 {
1437         if (flags & (LOOKUP_CREATE | LOOKUP_RENAME_TARGET))
1438                 return 0;
1439         if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG)
1440                 return 1;
1441         return !nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU);
1442 }
1443
1444 static int
1445 nfs_lookup_revalidate_done(struct inode *dir, struct dentry *dentry,
1446                            struct inode *inode, int error)
1447 {
1448         switch (error) {
1449         case 1:
1450                 dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is valid\n",
1451                         __func__, dentry);
1452                 return 1;
1453         case 0:
1454                 /*
1455                  * We can't d_drop the root of a disconnected tree:
1456                  * its d_hash is on the s_anon list and d_drop() would hide
1457                  * it from shrink_dcache_for_unmount(), leading to busy
1458                  * inodes on unmount and further oopses.
1459                  */
1460                 if (inode && IS_ROOT(dentry))
1461                         return 1;
1462                 dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is invalid\n",
1463                                 __func__, dentry);
1464                 return 0;
1465         }
1466         dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) lookup returned error %d\n",
1467                                 __func__, dentry, error);
1468         return error;
1469 }
1470
1471 static int
1472 nfs_lookup_revalidate_negative(struct inode *dir, struct dentry *dentry,
1473                                unsigned int flags)
1474 {
1475         int ret = 1;
1476         if (nfs_neg_need_reval(dir, dentry, flags)) {
1477                 if (flags & LOOKUP_RCU)
1478                         return -ECHILD;
1479                 ret = 0;
1480         }
1481         return nfs_lookup_revalidate_done(dir, dentry, NULL, ret);
1482 }
1483
1484 static int
1485 nfs_lookup_revalidate_delegated(struct inode *dir, struct dentry *dentry,
1486                                 struct inode *inode)
1487 {
1488         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
1489         return nfs_lookup_revalidate_done(dir, dentry, inode, 1);
1490 }
1491
1492 static int
1493 nfs_lookup_revalidate_dentry(struct inode *dir, struct dentry *dentry,
1494                              struct inode *inode)
1495 {
1496         struct nfs_fh *fhandle;
1497         struct nfs_fattr *fattr;
1498         struct nfs4_label *label;
1499         unsigned long dir_verifier;
1500         int ret;
1501
1502         ret = -ENOMEM;
1503         fhandle = nfs_alloc_fhandle();
1504         fattr = nfs_alloc_fattr();
1505         label = nfs4_label_alloc(NFS_SERVER(inode), GFP_KERNEL);
1506         if (fhandle == NULL || fattr == NULL || IS_ERR(label))
1507                 goto out;
1508
1509         dir_verifier = nfs_save_change_attribute(dir);
1510         ret = NFS_PROTO(dir)->lookup(dir, dentry, fhandle, fattr, label);
1511         if (ret < 0) {
1512                 switch (ret) {
1513                 case -ESTALE:
1514                 case -ENOENT:
1515                         ret = 0;
1516                         break;
1517                 case -ETIMEDOUT:
1518                         if (NFS_SERVER(inode)->flags & NFS_MOUNT_SOFTREVAL)
1519                                 ret = 1;
1520                 }
1521                 goto out;
1522         }
1523         ret = 0;
1524         if (nfs_compare_fh(NFS_FH(inode), fhandle))
1525                 goto out;
1526         if (nfs_refresh_inode(inode, fattr) < 0)
1527                 goto out;
1528
1529         nfs_setsecurity(inode, fattr, label);
1530         nfs_set_verifier(dentry, dir_verifier);
1531
1532         /* set a readdirplus hint that we had a cache miss */
1533         nfs_force_use_readdirplus(dir);
1534         ret = 1;
1535 out:
1536         nfs_free_fattr(fattr);
1537         nfs_free_fhandle(fhandle);
1538         nfs4_label_free(label);
1539
1540         /*
1541          * If the lookup failed despite the dentry change attribute being
1542          * a match, then we should revalidate the directory cache.
1543          */
1544         if (!ret && nfs_verify_change_attribute(dir, dentry->d_time))
1545                 nfs_mark_dir_for_revalidate(dir);
1546         return nfs_lookup_revalidate_done(dir, dentry, inode, ret);
1547 }
1548
1549 /*
1550  * This is called every time the dcache has a lookup hit,
1551  * and we should check whether we can really trust that
1552  * lookup.
1553  *
1554  * NOTE! The hit can be a negative hit too, don't assume
1555  * we have an inode!
1556  *
1557  * If the parent directory is seen to have changed, we throw out the
1558  * cached dentry and do a new lookup.
1559  */
1560 static int
1561 nfs_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
1562                          unsigned int flags)
1563 {
1564         struct inode *inode;
1565         int error;
1566
1567         nfs_inc_stats(dir, NFSIOS_DENTRYREVALIDATE);
1568         inode = d_inode(dentry);
1569
1570         if (!inode)
1571                 return nfs_lookup_revalidate_negative(dir, dentry, flags);
1572
1573         if (is_bad_inode(inode)) {
1574                 dfprintk(LOOKUPCACHE, "%s: %pd2 has dud inode\n",
1575                                 __func__, dentry);
1576                 goto out_bad;
1577         }
1578
1579         if (nfs_verifier_is_delegated(dentry))
1580                 return nfs_lookup_revalidate_delegated(dir, dentry, inode);
1581
1582         /* Force a full look up iff the parent directory has changed */
1583         if (!(flags & (LOOKUP_EXCL | LOOKUP_REVAL)) &&
1584             nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) {
1585                 error = nfs_lookup_verify_inode(inode, flags);
1586                 if (error) {
1587                         if (error == -ESTALE)
1588                                 nfs_mark_dir_for_revalidate(dir);
1589                         goto out_bad;
1590                 }
1591                 nfs_advise_use_readdirplus(dir);
1592                 goto out_valid;
1593         }
1594
1595         if (flags & LOOKUP_RCU)
1596                 return -ECHILD;
1597
1598         if (NFS_STALE(inode))
1599                 goto out_bad;
1600
1601         trace_nfs_lookup_revalidate_enter(dir, dentry, flags);
1602         error = nfs_lookup_revalidate_dentry(dir, dentry, inode);
1603         trace_nfs_lookup_revalidate_exit(dir, dentry, flags, error);
1604         return error;
1605 out_valid:
1606         return nfs_lookup_revalidate_done(dir, dentry, inode, 1);
1607 out_bad:
1608         if (flags & LOOKUP_RCU)
1609                 return -ECHILD;
1610         return nfs_lookup_revalidate_done(dir, dentry, inode, 0);
1611 }
1612
1613 static int
1614 __nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags,
1615                         int (*reval)(struct inode *, struct dentry *, unsigned int))
1616 {
1617         struct dentry *parent;
1618         struct inode *dir;
1619         int ret;
1620
1621         if (flags & LOOKUP_RCU) {
1622                 parent = READ_ONCE(dentry->d_parent);
1623                 dir = d_inode_rcu(parent);
1624                 if (!dir)
1625                         return -ECHILD;
1626                 ret = reval(dir, dentry, flags);
1627                 if (parent != READ_ONCE(dentry->d_parent))
1628                         return -ECHILD;
1629         } else {
1630                 parent = dget_parent(dentry);
1631                 ret = reval(d_inode(parent), dentry, flags);
1632                 dput(parent);
1633         }
1634         return ret;
1635 }
1636
1637 static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
1638 {
1639         return __nfs_lookup_revalidate(dentry, flags, nfs_do_lookup_revalidate);
1640 }
1641
1642 /*
1643  * A weaker form of d_revalidate for revalidating just the d_inode(dentry)
1644  * when we don't really care about the dentry name. This is called when a
1645  * pathwalk ends on a dentry that was not found via a normal lookup in the
1646  * parent dir (e.g.: ".", "..", procfs symlinks or mountpoint traversals).
1647  *
1648  * In this situation, we just want to verify that the inode itself is OK
1649  * since the dentry might have changed on the server.
1650  */
1651 static int nfs_weak_revalidate(struct dentry *dentry, unsigned int flags)
1652 {
1653         struct inode *inode = d_inode(dentry);
1654         int error = 0;
1655
1656         /*
1657          * I believe we can only get a negative dentry here in the case of a
1658          * procfs-style symlink. Just assume it's correct for now, but we may
1659          * eventually need to do something more here.
1660          */
1661         if (!inode) {
1662                 dfprintk(LOOKUPCACHE, "%s: %pd2 has negative inode\n",
1663                                 __func__, dentry);
1664                 return 1;
1665         }
1666
1667         if (is_bad_inode(inode)) {
1668                 dfprintk(LOOKUPCACHE, "%s: %pd2 has dud inode\n",
1669                                 __func__, dentry);
1670                 return 0;
1671         }
1672
1673         error = nfs_lookup_verify_inode(inode, flags);
1674         dfprintk(LOOKUPCACHE, "NFS: %s: inode %lu is %s\n",
1675                         __func__, inode->i_ino, error ? "invalid" : "valid");
1676         return !error;
1677 }
1678
1679 /*
1680  * This is called from dput() when d_count is going to 0.
1681  */
1682 static int nfs_dentry_delete(const struct dentry *dentry)
1683 {
1684         dfprintk(VFS, "NFS: dentry_delete(%pd2, %x)\n",
1685                 dentry, dentry->d_flags);
1686
1687         /* Unhash any dentry with a stale inode */
1688         if (d_really_is_positive(dentry) && NFS_STALE(d_inode(dentry)))
1689                 return 1;
1690
1691         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
1692                 /* Unhash it, so that ->d_iput() would be called */
1693                 return 1;
1694         }
1695         if (!(dentry->d_sb->s_flags & SB_ACTIVE)) {
1696                 /* Unhash it, so that ancestors of killed async unlink
1697                  * files will be cleaned up during umount */
1698                 return 1;
1699         }
1700         return 0;
1701
1702 }
1703
1704 /* Ensure that we revalidate inode->i_nlink */
1705 static void nfs_drop_nlink(struct inode *inode)
1706 {
1707         spin_lock(&inode->i_lock);
1708         /* drop the inode if we're reasonably sure this is the last link */
1709         if (inode->i_nlink > 0)
1710                 drop_nlink(inode);
1711         NFS_I(inode)->attr_gencount = nfs_inc_attr_generation_counter();
1712         nfs_set_cache_invalid(
1713                 inode, NFS_INO_INVALID_CHANGE | NFS_INO_INVALID_CTIME |
1714                                NFS_INO_INVALID_NLINK);
1715         spin_unlock(&inode->i_lock);
1716 }
1717
1718 /*
1719  * Called when the dentry loses inode.
1720  * We use it to clean up silly-renamed files.
1721  */
1722 static void nfs_dentry_iput(struct dentry *dentry, struct inode *inode)
1723 {
1724         if (S_ISDIR(inode->i_mode))
1725                 /* drop any readdir cache as it could easily be old */
1726                 nfs_set_cache_invalid(inode, NFS_INO_INVALID_DATA);
1727
1728         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
1729                 nfs_complete_unlink(dentry, inode);
1730                 nfs_drop_nlink(inode);
1731         }
1732         iput(inode);
1733 }
1734
1735 static void nfs_d_release(struct dentry *dentry)
1736 {
1737         /* free cached devname value, if it survived that far */
1738         if (unlikely(dentry->d_fsdata)) {
1739                 if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
1740                         WARN_ON(1);
1741                 else
1742                         kfree(dentry->d_fsdata);
1743         }
1744 }
1745
1746 const struct dentry_operations nfs_dentry_operations = {
1747         .d_revalidate   = nfs_lookup_revalidate,
1748         .d_weak_revalidate      = nfs_weak_revalidate,
1749         .d_delete       = nfs_dentry_delete,
1750         .d_iput         = nfs_dentry_iput,
1751         .d_automount    = nfs_d_automount,
1752         .d_release      = nfs_d_release,
1753 };
1754 EXPORT_SYMBOL_GPL(nfs_dentry_operations);
1755
1756 struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
1757 {
1758         struct dentry *res;
1759         struct inode *inode = NULL;
1760         struct nfs_fh *fhandle = NULL;
1761         struct nfs_fattr *fattr = NULL;
1762         struct nfs4_label *label = NULL;
1763         unsigned long dir_verifier;
1764         int error;
1765
1766         dfprintk(VFS, "NFS: lookup(%pd2)\n", dentry);
1767         nfs_inc_stats(dir, NFSIOS_VFSLOOKUP);
1768
1769         if (unlikely(dentry->d_name.len > NFS_SERVER(dir)->namelen))
1770                 return ERR_PTR(-ENAMETOOLONG);
1771
1772         /*
1773          * If we're doing an exclusive create, optimize away the lookup
1774          * but don't hash the dentry.
1775          */
1776         if (nfs_is_exclusive_create(dir, flags) || flags & LOOKUP_RENAME_TARGET)
1777                 return NULL;
1778
1779         res = ERR_PTR(-ENOMEM);
1780         fhandle = nfs_alloc_fhandle();
1781         fattr = nfs_alloc_fattr();
1782         if (fhandle == NULL || fattr == NULL)
1783                 goto out;
1784
1785         label = nfs4_label_alloc(NFS_SERVER(dir), GFP_NOWAIT);
1786         if (IS_ERR(label))
1787                 goto out;
1788
1789         dir_verifier = nfs_save_change_attribute(dir);
1790         trace_nfs_lookup_enter(dir, dentry, flags);
1791         error = NFS_PROTO(dir)->lookup(dir, dentry, fhandle, fattr, label);
1792         if (error == -ENOENT)
1793                 goto no_entry;
1794         if (error < 0) {
1795                 res = ERR_PTR(error);
1796                 goto out_label;
1797         }
1798         inode = nfs_fhget(dentry->d_sb, fhandle, fattr, label);
1799         res = ERR_CAST(inode);
1800         if (IS_ERR(res))
1801                 goto out_label;
1802
1803         /* Notify readdir to use READDIRPLUS */
1804         nfs_force_use_readdirplus(dir);
1805
1806 no_entry:
1807         res = d_splice_alias(inode, dentry);
1808         if (res != NULL) {
1809                 if (IS_ERR(res))
1810                         goto out_label;
1811                 dentry = res;
1812         }
1813         nfs_set_verifier(dentry, dir_verifier);
1814 out_label:
1815         trace_nfs_lookup_exit(dir, dentry, flags, error);
1816         nfs4_label_free(label);
1817 out:
1818         nfs_free_fattr(fattr);
1819         nfs_free_fhandle(fhandle);
1820         return res;
1821 }
1822 EXPORT_SYMBOL_GPL(nfs_lookup);
1823
1824 #if IS_ENABLED(CONFIG_NFS_V4)
1825 static int nfs4_lookup_revalidate(struct dentry *, unsigned int);
1826
1827 const struct dentry_operations nfs4_dentry_operations = {
1828         .d_revalidate   = nfs4_lookup_revalidate,
1829         .d_weak_revalidate      = nfs_weak_revalidate,
1830         .d_delete       = nfs_dentry_delete,
1831         .d_iput         = nfs_dentry_iput,
1832         .d_automount    = nfs_d_automount,
1833         .d_release      = nfs_d_release,
1834 };
1835 EXPORT_SYMBOL_GPL(nfs4_dentry_operations);
1836
1837 static fmode_t flags_to_mode(int flags)
1838 {
1839         fmode_t res = (__force fmode_t)flags & FMODE_EXEC;
1840         if ((flags & O_ACCMODE) != O_WRONLY)
1841                 res |= FMODE_READ;
1842         if ((flags & O_ACCMODE) != O_RDONLY)
1843                 res |= FMODE_WRITE;
1844         return res;
1845 }
1846
1847 static struct nfs_open_context *create_nfs_open_context(struct dentry *dentry, int open_flags, struct file *filp)
1848 {
1849         return alloc_nfs_open_context(dentry, flags_to_mode(open_flags), filp);
1850 }
1851
1852 static int do_open(struct inode *inode, struct file *filp)
1853 {
1854         nfs_fscache_open_file(inode, filp);
1855         return 0;
1856 }
1857
1858 static int nfs_finish_open(struct nfs_open_context *ctx,
1859                            struct dentry *dentry,
1860                            struct file *file, unsigned open_flags)
1861 {
1862         int err;
1863
1864         err = finish_open(file, dentry, do_open);
1865         if (err)
1866                 goto out;
1867         if (S_ISREG(file->f_path.dentry->d_inode->i_mode))
1868                 nfs_file_set_open_context(file, ctx);
1869         else
1870                 err = -EOPENSTALE;
1871 out:
1872         return err;
1873 }
1874
1875 int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
1876                     struct file *file, unsigned open_flags,
1877                     umode_t mode)
1878 {
1879         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
1880         struct nfs_open_context *ctx;
1881         struct dentry *res;
1882         struct iattr attr = { .ia_valid = ATTR_OPEN };
1883         struct inode *inode;
1884         unsigned int lookup_flags = 0;
1885         bool switched = false;
1886         int created = 0;
1887         int err;
1888
1889         /* Expect a negative dentry */
1890         BUG_ON(d_inode(dentry));
1891
1892         dfprintk(VFS, "NFS: atomic_open(%s/%lu), %pd\n",
1893                         dir->i_sb->s_id, dir->i_ino, dentry);
1894
1895         err = nfs_check_flags(open_flags);
1896         if (err)
1897                 return err;
1898
1899         /* NFS only supports OPEN on regular files */
1900         if ((open_flags & O_DIRECTORY)) {
1901                 if (!d_in_lookup(dentry)) {
1902                         /*
1903                          * Hashed negative dentry with O_DIRECTORY: dentry was
1904                          * revalidated and is fine, no need to perform lookup
1905                          * again
1906                          */
1907                         return -ENOENT;
1908                 }
1909                 lookup_flags = LOOKUP_OPEN|LOOKUP_DIRECTORY;
1910                 goto no_open;
1911         }
1912
1913         if (dentry->d_name.len > NFS_SERVER(dir)->namelen)
1914                 return -ENAMETOOLONG;
1915
1916         if (open_flags & O_CREAT) {
1917                 struct nfs_server *server = NFS_SERVER(dir);
1918
1919                 if (!(server->attr_bitmask[2] & FATTR4_WORD2_MODE_UMASK))
1920                         mode &= ~current_umask();
1921
1922                 attr.ia_valid |= ATTR_MODE;
1923                 attr.ia_mode = mode;
1924         }
1925         if (open_flags & O_TRUNC) {
1926                 attr.ia_valid |= ATTR_SIZE;
1927                 attr.ia_size = 0;
1928         }
1929
1930         if (!(open_flags & O_CREAT) && !d_in_lookup(dentry)) {
1931                 d_drop(dentry);
1932                 switched = true;
1933                 dentry = d_alloc_parallel(dentry->d_parent,
1934                                           &dentry->d_name, &wq);
1935                 if (IS_ERR(dentry))
1936                         return PTR_ERR(dentry);
1937                 if (unlikely(!d_in_lookup(dentry)))
1938                         return finish_no_open(file, dentry);
1939         }
1940
1941         ctx = create_nfs_open_context(dentry, open_flags, file);
1942         err = PTR_ERR(ctx);
1943         if (IS_ERR(ctx))
1944                 goto out;
1945
1946         trace_nfs_atomic_open_enter(dir, ctx, open_flags);
1947         inode = NFS_PROTO(dir)->open_context(dir, ctx, open_flags, &attr, &created);
1948         if (created)
1949                 file->f_mode |= FMODE_CREATED;
1950         if (IS_ERR(inode)) {
1951                 err = PTR_ERR(inode);
1952                 trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
1953                 put_nfs_open_context(ctx);
1954                 d_drop(dentry);
1955                 switch (err) {
1956                 case -ENOENT:
1957                         d_splice_alias(NULL, dentry);
1958                         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
1959                         break;
1960                 case -EISDIR:
1961                 case -ENOTDIR:
1962                         goto no_open;
1963                 case -ELOOP:
1964                         if (!(open_flags & O_NOFOLLOW))
1965                                 goto no_open;
1966                         break;
1967                         /* case -EINVAL: */
1968                 default:
1969                         break;
1970                 }
1971                 goto out;
1972         }
1973
1974         err = nfs_finish_open(ctx, ctx->dentry, file, open_flags);
1975         trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
1976         put_nfs_open_context(ctx);
1977 out:
1978         if (unlikely(switched)) {
1979                 d_lookup_done(dentry);
1980                 dput(dentry);
1981         }
1982         return err;
1983
1984 no_open:
1985         res = nfs_lookup(dir, dentry, lookup_flags);
1986         if (switched) {
1987                 d_lookup_done(dentry);
1988                 if (!res)
1989                         res = dentry;
1990                 else
1991                         dput(dentry);
1992         }
1993         if (IS_ERR(res))
1994                 return PTR_ERR(res);
1995         return finish_no_open(file, res);
1996 }
1997 EXPORT_SYMBOL_GPL(nfs_atomic_open);
1998
1999 static int
2000 nfs4_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
2001                           unsigned int flags)
2002 {
2003         struct inode *inode;
2004
2005         if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY))
2006                 goto full_reval;
2007         if (d_mountpoint(dentry))
2008                 goto full_reval;
2009
2010         inode = d_inode(dentry);
2011
2012         /* We can't create new files in nfs_open_revalidate(), so we
2013          * optimize away revalidation of negative dentries.
2014          */
2015         if (inode == NULL)
2016                 goto full_reval;
2017
2018         if (nfs_verifier_is_delegated(dentry))
2019                 return nfs_lookup_revalidate_delegated(dir, dentry, inode);
2020
2021         /* NFS only supports OPEN on regular files */
2022         if (!S_ISREG(inode->i_mode))
2023                 goto full_reval;
2024
2025         /* We cannot do exclusive creation on a positive dentry */
2026         if (flags & (LOOKUP_EXCL | LOOKUP_REVAL))
2027                 goto reval_dentry;
2028
2029         /* Check if the directory changed */
2030         if (!nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU))
2031                 goto reval_dentry;
2032
2033         /* Let f_op->open() actually open (and revalidate) the file */
2034         return 1;
2035 reval_dentry:
2036         if (flags & LOOKUP_RCU)
2037                 return -ECHILD;
2038         return nfs_lookup_revalidate_dentry(dir, dentry, inode);
2039
2040 full_reval:
2041         return nfs_do_lookup_revalidate(dir, dentry, flags);
2042 }
2043
2044 static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
2045 {
2046         return __nfs_lookup_revalidate(dentry, flags,
2047                         nfs4_do_lookup_revalidate);
2048 }
2049
2050 #endif /* CONFIG_NFSV4 */
2051
2052 struct dentry *
2053 nfs_add_or_obtain(struct dentry *dentry, struct nfs_fh *fhandle,
2054                                 struct nfs_fattr *fattr,
2055                                 struct nfs4_label *label)
2056 {
2057         struct dentry *parent = dget_parent(dentry);
2058         struct inode *dir = d_inode(parent);
2059         struct inode *inode;
2060         struct dentry *d;
2061         int error;
2062
2063         d_drop(dentry);
2064
2065         if (fhandle->size == 0) {
2066                 error = NFS_PROTO(dir)->lookup(dir, dentry, fhandle, fattr, NULL);
2067                 if (error)
2068                         goto out_error;
2069         }
2070         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
2071         if (!(fattr->valid & NFS_ATTR_FATTR)) {
2072                 struct nfs_server *server = NFS_SB(dentry->d_sb);
2073                 error = server->nfs_client->rpc_ops->getattr(server, fhandle,
2074                                 fattr, NULL, NULL);
2075                 if (error < 0)
2076                         goto out_error;
2077         }
2078         inode = nfs_fhget(dentry->d_sb, fhandle, fattr, label);
2079         d = d_splice_alias(inode, dentry);
2080 out:
2081         dput(parent);
2082         return d;
2083 out_error:
2084         d = ERR_PTR(error);
2085         goto out;
2086 }
2087 EXPORT_SYMBOL_GPL(nfs_add_or_obtain);
2088
2089 /*
2090  * Code common to create, mkdir, and mknod.
2091  */
2092 int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
2093                                 struct nfs_fattr *fattr,
2094                                 struct nfs4_label *label)
2095 {
2096         struct dentry *d;
2097
2098         d = nfs_add_or_obtain(dentry, fhandle, fattr, label);
2099         if (IS_ERR(d))
2100                 return PTR_ERR(d);
2101
2102         /* Callers don't care */
2103         dput(d);
2104         return 0;
2105 }
2106 EXPORT_SYMBOL_GPL(nfs_instantiate);
2107
2108 /*
2109  * Following a failed create operation, we drop the dentry rather
2110  * than retain a negative dentry. This avoids a problem in the event
2111  * that the operation succeeded on the server, but an error in the
2112  * reply path made it appear to have failed.
2113  */
2114 int nfs_create(struct user_namespace *mnt_userns, struct inode *dir,
2115                struct dentry *dentry, umode_t mode, bool excl)
2116 {
2117         struct iattr attr;
2118         int open_flags = excl ? O_CREAT | O_EXCL : O_CREAT;
2119         int error;
2120
2121         dfprintk(VFS, "NFS: create(%s/%lu), %pd\n",
2122                         dir->i_sb->s_id, dir->i_ino, dentry);
2123
2124         attr.ia_mode = mode;
2125         attr.ia_valid = ATTR_MODE;
2126
2127         trace_nfs_create_enter(dir, dentry, open_flags);
2128         error = NFS_PROTO(dir)->create(dir, dentry, &attr, open_flags);
2129         trace_nfs_create_exit(dir, dentry, open_flags, error);
2130         if (error != 0)
2131                 goto out_err;
2132         return 0;
2133 out_err:
2134         d_drop(dentry);
2135         return error;
2136 }
2137 EXPORT_SYMBOL_GPL(nfs_create);
2138
2139 /*
2140  * See comments for nfs_proc_create regarding failed operations.
2141  */
2142 int
2143 nfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
2144           struct dentry *dentry, umode_t mode, dev_t rdev)
2145 {
2146         struct iattr attr;
2147         int status;
2148
2149         dfprintk(VFS, "NFS: mknod(%s/%lu), %pd\n",
2150                         dir->i_sb->s_id, dir->i_ino, dentry);
2151
2152         attr.ia_mode = mode;
2153         attr.ia_valid = ATTR_MODE;
2154
2155         trace_nfs_mknod_enter(dir, dentry);
2156         status = NFS_PROTO(dir)->mknod(dir, dentry, &attr, rdev);
2157         trace_nfs_mknod_exit(dir, dentry, status);
2158         if (status != 0)
2159                 goto out_err;
2160         return 0;
2161 out_err:
2162         d_drop(dentry);
2163         return status;
2164 }
2165 EXPORT_SYMBOL_GPL(nfs_mknod);
2166
2167 /*
2168  * See comments for nfs_proc_create regarding failed operations.
2169  */
2170 int nfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
2171               struct dentry *dentry, umode_t mode)
2172 {
2173         struct iattr attr;
2174         int error;
2175
2176         dfprintk(VFS, "NFS: mkdir(%s/%lu), %pd\n",
2177                         dir->i_sb->s_id, dir->i_ino, dentry);
2178
2179         attr.ia_valid = ATTR_MODE;
2180         attr.ia_mode = mode | S_IFDIR;
2181
2182         trace_nfs_mkdir_enter(dir, dentry);
2183         error = NFS_PROTO(dir)->mkdir(dir, dentry, &attr);
2184         trace_nfs_mkdir_exit(dir, dentry, error);
2185         if (error != 0)
2186                 goto out_err;
2187         return 0;
2188 out_err:
2189         d_drop(dentry);
2190         return error;
2191 }
2192 EXPORT_SYMBOL_GPL(nfs_mkdir);
2193
2194 static void nfs_dentry_handle_enoent(struct dentry *dentry)
2195 {
2196         if (simple_positive(dentry))
2197                 d_delete(dentry);
2198 }
2199
2200 int nfs_rmdir(struct inode *dir, struct dentry *dentry)
2201 {
2202         int error;
2203
2204         dfprintk(VFS, "NFS: rmdir(%s/%lu), %pd\n",
2205                         dir->i_sb->s_id, dir->i_ino, dentry);
2206
2207         trace_nfs_rmdir_enter(dir, dentry);
2208         if (d_really_is_positive(dentry)) {
2209                 down_write(&NFS_I(d_inode(dentry))->rmdir_sem);
2210                 error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
2211                 /* Ensure the VFS deletes this inode */
2212                 switch (error) {
2213                 case 0:
2214                         clear_nlink(d_inode(dentry));
2215                         break;
2216                 case -ENOENT:
2217                         nfs_dentry_handle_enoent(dentry);
2218                 }
2219                 up_write(&NFS_I(d_inode(dentry))->rmdir_sem);
2220         } else
2221                 error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
2222         trace_nfs_rmdir_exit(dir, dentry, error);
2223
2224         return error;
2225 }
2226 EXPORT_SYMBOL_GPL(nfs_rmdir);
2227
2228 /*
2229  * Remove a file after making sure there are no pending writes,
2230  * and after checking that the file has only one user.
2231  *
2232  * We invalidate the attribute cache and free the inode prior to the operation
2233  * to avoid possible races if the server reuses the inode.
2234  */
2235 static int nfs_safe_remove(struct dentry *dentry)
2236 {
2237         struct inode *dir = d_inode(dentry->d_parent);
2238         struct inode *inode = d_inode(dentry);
2239         int error = -EBUSY;
2240
2241         dfprintk(VFS, "NFS: safe_remove(%pd2)\n", dentry);
2242
2243         /* If the dentry was sillyrenamed, we simply call d_delete() */
2244         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
2245                 error = 0;
2246                 goto out;
2247         }
2248
2249         trace_nfs_remove_enter(dir, dentry);
2250         if (inode != NULL) {
2251                 error = NFS_PROTO(dir)->remove(dir, dentry);
2252                 if (error == 0)
2253                         nfs_drop_nlink(inode);
2254         } else
2255                 error = NFS_PROTO(dir)->remove(dir, dentry);
2256         if (error == -ENOENT)
2257                 nfs_dentry_handle_enoent(dentry);
2258         trace_nfs_remove_exit(dir, dentry, error);
2259 out:
2260         return error;
2261 }
2262
2263 /*  We do silly rename. In case sillyrename() returns -EBUSY, the inode
2264  *  belongs to an active ".nfs..." file and we return -EBUSY.
2265  *
2266  *  If sillyrename() returns 0, we do nothing, otherwise we unlink.
2267  */
2268 int nfs_unlink(struct inode *dir, struct dentry *dentry)
2269 {
2270         int error;
2271         int need_rehash = 0;
2272
2273         dfprintk(VFS, "NFS: unlink(%s/%lu, %pd)\n", dir->i_sb->s_id,
2274                 dir->i_ino, dentry);
2275
2276         trace_nfs_unlink_enter(dir, dentry);
2277         spin_lock(&dentry->d_lock);
2278         if (d_count(dentry) > 1) {
2279                 spin_unlock(&dentry->d_lock);
2280                 /* Start asynchronous writeout of the inode */
2281                 write_inode_now(d_inode(dentry), 0);
2282                 error = nfs_sillyrename(dir, dentry);
2283                 goto out;
2284         }
2285         if (!d_unhashed(dentry)) {
2286                 __d_drop(dentry);
2287                 need_rehash = 1;
2288         }
2289         spin_unlock(&dentry->d_lock);
2290         error = nfs_safe_remove(dentry);
2291         if (!error || error == -ENOENT) {
2292                 nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
2293         } else if (need_rehash)
2294                 d_rehash(dentry);
2295 out:
2296         trace_nfs_unlink_exit(dir, dentry, error);
2297         return error;
2298 }
2299 EXPORT_SYMBOL_GPL(nfs_unlink);
2300
2301 /*
2302  * To create a symbolic link, most file systems instantiate a new inode,
2303  * add a page to it containing the path, then write it out to the disk
2304  * using prepare_write/commit_write.
2305  *
2306  * Unfortunately the NFS client can't create the in-core inode first
2307  * because it needs a file handle to create an in-core inode (see
2308  * fs/nfs/inode.c:nfs_fhget).  We only have a file handle *after* the
2309  * symlink request has completed on the server.
2310  *
2311  * So instead we allocate a raw page, copy the symname into it, then do
2312  * the SYMLINK request with the page as the buffer.  If it succeeds, we
2313  * now have a new file handle and can instantiate an in-core NFS inode
2314  * and move the raw page into its mapping.
2315  */
2316 int nfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
2317                 struct dentry *dentry, const char *symname)
2318 {
2319         struct page *page;
2320         char *kaddr;
2321         struct iattr attr;
2322         unsigned int pathlen = strlen(symname);
2323         int error;
2324
2325         dfprintk(VFS, "NFS: symlink(%s/%lu, %pd, %s)\n", dir->i_sb->s_id,
2326                 dir->i_ino, dentry, symname);
2327
2328         if (pathlen > PAGE_SIZE)
2329                 return -ENAMETOOLONG;
2330
2331         attr.ia_mode = S_IFLNK | S_IRWXUGO;
2332         attr.ia_valid = ATTR_MODE;
2333
2334         page = alloc_page(GFP_USER);
2335         if (!page)
2336                 return -ENOMEM;
2337
2338         kaddr = page_address(page);
2339         memcpy(kaddr, symname, pathlen);
2340         if (pathlen < PAGE_SIZE)
2341                 memset(kaddr + pathlen, 0, PAGE_SIZE - pathlen);
2342
2343         trace_nfs_symlink_enter(dir, dentry);
2344         error = NFS_PROTO(dir)->symlink(dir, dentry, page, pathlen, &attr);
2345         trace_nfs_symlink_exit(dir, dentry, error);
2346         if (error != 0) {
2347                 dfprintk(VFS, "NFS: symlink(%s/%lu, %pd, %s) error %d\n",
2348                         dir->i_sb->s_id, dir->i_ino,
2349                         dentry, symname, error);
2350                 d_drop(dentry);
2351                 __free_page(page);
2352                 return error;
2353         }
2354
2355         /*
2356          * No big deal if we can't add this page to the page cache here.
2357          * READLINK will get the missing page from the server if needed.
2358          */
2359         if (!add_to_page_cache_lru(page, d_inode(dentry)->i_mapping, 0,
2360                                                         GFP_KERNEL)) {
2361                 SetPageUptodate(page);
2362                 unlock_page(page);
2363                 /*
2364                  * add_to_page_cache_lru() grabs an extra page refcount.
2365                  * Drop it here to avoid leaking this page later.
2366                  */
2367                 put_page(page);
2368         } else
2369                 __free_page(page);
2370
2371         return 0;
2372 }
2373 EXPORT_SYMBOL_GPL(nfs_symlink);
2374
2375 int
2376 nfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
2377 {
2378         struct inode *inode = d_inode(old_dentry);
2379         int error;
2380
2381         dfprintk(VFS, "NFS: link(%pd2 -> %pd2)\n",
2382                 old_dentry, dentry);
2383
2384         trace_nfs_link_enter(inode, dir, dentry);
2385         d_drop(dentry);
2386         error = NFS_PROTO(dir)->link(inode, dir, &dentry->d_name);
2387         if (error == 0) {
2388                 ihold(inode);
2389                 d_add(dentry, inode);
2390         }
2391         trace_nfs_link_exit(inode, dir, dentry, error);
2392         return error;
2393 }
2394 EXPORT_SYMBOL_GPL(nfs_link);
2395
2396 /*
2397  * RENAME
2398  * FIXME: Some nfsds, like the Linux user space nfsd, may generate a
2399  * different file handle for the same inode after a rename (e.g. when
2400  * moving to a different directory). A fail-safe method to do so would
2401  * be to look up old_dir/old_name, create a link to new_dir/new_name and
2402  * rename the old file using the sillyrename stuff. This way, the original
2403  * file in old_dir will go away when the last process iput()s the inode.
2404  *
2405  * FIXED.
2406  *
2407  * It actually works quite well. One needs to have the possibility for
2408  * at least one ".nfs..." file in each directory the file ever gets
2409  * moved or linked to which happens automagically with the new
2410  * implementation that only depends on the dcache stuff instead of
2411  * using the inode layer
2412  *
2413  * Unfortunately, things are a little more complicated than indicated
2414  * above. For a cross-directory move, we want to make sure we can get
2415  * rid of the old inode after the operation.  This means there must be
2416  * no pending writes (if it's a file), and the use count must be 1.
2417  * If these conditions are met, we can drop the dentries before doing
2418  * the rename.
2419  */
2420 int nfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
2421                struct dentry *old_dentry, struct inode *new_dir,
2422                struct dentry *new_dentry, unsigned int flags)
2423 {
2424         struct inode *old_inode = d_inode(old_dentry);
2425         struct inode *new_inode = d_inode(new_dentry);
2426         struct dentry *dentry = NULL, *rehash = NULL;
2427         struct rpc_task *task;
2428         int error = -EBUSY;
2429
2430         if (flags)
2431                 return -EINVAL;
2432
2433         dfprintk(VFS, "NFS: rename(%pd2 -> %pd2, ct=%d)\n",
2434                  old_dentry, new_dentry,
2435                  d_count(new_dentry));
2436
2437         trace_nfs_rename_enter(old_dir, old_dentry, new_dir, new_dentry);
2438         /*
2439          * For non-directories, check whether the target is busy and if so,
2440          * make a copy of the dentry and then do a silly-rename. If the
2441          * silly-rename succeeds, the copied dentry is hashed and becomes
2442          * the new target.
2443          */
2444         if (new_inode && !S_ISDIR(new_inode->i_mode)) {
2445                 /*
2446                  * To prevent any new references to the target during the
2447                  * rename, we unhash the dentry in advance.
2448                  */
2449                 if (!d_unhashed(new_dentry)) {
2450                         d_drop(new_dentry);
2451                         rehash = new_dentry;
2452                 }
2453
2454                 if (d_count(new_dentry) > 2) {
2455                         int err;
2456
2457                         /* copy the target dentry's name */
2458                         dentry = d_alloc(new_dentry->d_parent,
2459                                          &new_dentry->d_name);
2460                         if (!dentry)
2461                                 goto out;
2462
2463                         /* silly-rename the existing target ... */
2464                         err = nfs_sillyrename(new_dir, new_dentry);
2465                         if (err)
2466                                 goto out;
2467
2468                         new_dentry = dentry;
2469                         rehash = NULL;
2470                         new_inode = NULL;
2471                 }
2472         }
2473
2474         task = nfs_async_rename(old_dir, new_dir, old_dentry, new_dentry, NULL);
2475         if (IS_ERR(task)) {
2476                 error = PTR_ERR(task);
2477                 goto out;
2478         }
2479
2480         error = rpc_wait_for_completion_task(task);
2481         if (error != 0) {
2482                 ((struct nfs_renamedata *)task->tk_calldata)->cancelled = 1;
2483                 /* Paired with the atomic_dec_and_test() barrier in rpc_do_put_task() */
2484                 smp_wmb();
2485         } else
2486                 error = task->tk_status;
2487         rpc_put_task(task);
2488         /* Ensure the inode attributes are revalidated */
2489         if (error == 0) {
2490                 spin_lock(&old_inode->i_lock);
2491                 NFS_I(old_inode)->attr_gencount = nfs_inc_attr_generation_counter();
2492                 nfs_set_cache_invalid(old_inode, NFS_INO_INVALID_CHANGE |
2493                                                          NFS_INO_INVALID_CTIME |
2494                                                          NFS_INO_REVAL_FORCED);
2495                 spin_unlock(&old_inode->i_lock);
2496         }
2497 out:
2498         if (rehash)
2499                 d_rehash(rehash);
2500         trace_nfs_rename_exit(old_dir, old_dentry,
2501                         new_dir, new_dentry, error);
2502         if (!error) {
2503                 if (new_inode != NULL)
2504                         nfs_drop_nlink(new_inode);
2505                 /*
2506                  * The d_move() should be here instead of in an async RPC completion
2507                  * handler because we need the proper locks to move the dentry.  If
2508                  * we're interrupted by a signal, the async RPC completion handler
2509                  * should mark the directories for revalidation.
2510                  */
2511                 d_move(old_dentry, new_dentry);
2512                 nfs_set_verifier(old_dentry,
2513                                         nfs_save_change_attribute(new_dir));
2514         } else if (error == -ENOENT)
2515                 nfs_dentry_handle_enoent(old_dentry);
2516
2517         /* new dentry created? */
2518         if (dentry)
2519                 dput(dentry);
2520         return error;
2521 }
2522 EXPORT_SYMBOL_GPL(nfs_rename);
2523
2524 static DEFINE_SPINLOCK(nfs_access_lru_lock);
2525 static LIST_HEAD(nfs_access_lru_list);
2526 static atomic_long_t nfs_access_nr_entries;
2527
2528 static unsigned long nfs_access_max_cachesize = 4*1024*1024;
2529 module_param(nfs_access_max_cachesize, ulong, 0644);
2530 MODULE_PARM_DESC(nfs_access_max_cachesize, "NFS access maximum total cache length");
2531
2532 static void nfs_access_free_entry(struct nfs_access_entry *entry)
2533 {
2534         put_cred(entry->cred);
2535         kfree_rcu(entry, rcu_head);
2536         smp_mb__before_atomic();
2537         atomic_long_dec(&nfs_access_nr_entries);
2538         smp_mb__after_atomic();
2539 }
2540
2541 static void nfs_access_free_list(struct list_head *head)
2542 {
2543         struct nfs_access_entry *cache;
2544
2545         while (!list_empty(head)) {
2546                 cache = list_entry(head->next, struct nfs_access_entry, lru);
2547                 list_del(&cache->lru);
2548                 nfs_access_free_entry(cache);
2549         }
2550 }
2551
2552 static unsigned long
2553 nfs_do_access_cache_scan(unsigned int nr_to_scan)
2554 {
2555         LIST_HEAD(head);
2556         struct nfs_inode *nfsi, *next;
2557         struct nfs_access_entry *cache;
2558         long freed = 0;
2559
2560         spin_lock(&nfs_access_lru_lock);
2561         list_for_each_entry_safe(nfsi, next, &nfs_access_lru_list, access_cache_inode_lru) {
2562                 struct inode *inode;
2563
2564                 if (nr_to_scan-- == 0)
2565                         break;
2566                 inode = &nfsi->vfs_inode;
2567                 spin_lock(&inode->i_lock);
2568                 if (list_empty(&nfsi->access_cache_entry_lru))
2569                         goto remove_lru_entry;
2570                 cache = list_entry(nfsi->access_cache_entry_lru.next,
2571                                 struct nfs_access_entry, lru);
2572                 list_move(&cache->lru, &head);
2573                 rb_erase(&cache->rb_node, &nfsi->access_cache);
2574                 freed++;
2575                 if (!list_empty(&nfsi->access_cache_entry_lru))
2576                         list_move_tail(&nfsi->access_cache_inode_lru,
2577                                         &nfs_access_lru_list);
2578                 else {
2579 remove_lru_entry:
2580                         list_del_init(&nfsi->access_cache_inode_lru);
2581                         smp_mb__before_atomic();
2582                         clear_bit(NFS_INO_ACL_LRU_SET, &nfsi->flags);
2583                         smp_mb__after_atomic();
2584                 }
2585                 spin_unlock(&inode->i_lock);
2586         }
2587         spin_unlock(&nfs_access_lru_lock);
2588         nfs_access_free_list(&head);
2589         return freed;
2590 }
2591
2592 unsigned long
2593 nfs_access_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
2594 {
2595         int nr_to_scan = sc->nr_to_scan;
2596         gfp_t gfp_mask = sc->gfp_mask;
2597
2598         if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
2599                 return SHRINK_STOP;
2600         return nfs_do_access_cache_scan(nr_to_scan);
2601 }
2602
2603
2604 unsigned long
2605 nfs_access_cache_count(struct shrinker *shrink, struct shrink_control *sc)
2606 {
2607         return vfs_pressure_ratio(atomic_long_read(&nfs_access_nr_entries));
2608 }
2609
2610 static void
2611 nfs_access_cache_enforce_limit(void)
2612 {
2613         long nr_entries = atomic_long_read(&nfs_access_nr_entries);
2614         unsigned long diff;
2615         unsigned int nr_to_scan;
2616
2617         if (nr_entries < 0 || nr_entries <= nfs_access_max_cachesize)
2618                 return;
2619         nr_to_scan = 100;
2620         diff = nr_entries - nfs_access_max_cachesize;
2621         if (diff < nr_to_scan)
2622                 nr_to_scan = diff;
2623         nfs_do_access_cache_scan(nr_to_scan);
2624 }
2625
2626 static void __nfs_access_zap_cache(struct nfs_inode *nfsi, struct list_head *head)
2627 {
2628         struct rb_root *root_node = &nfsi->access_cache;
2629         struct rb_node *n;
2630         struct nfs_access_entry *entry;
2631
2632         /* Unhook entries from the cache */
2633         while ((n = rb_first(root_node)) != NULL) {
2634                 entry = rb_entry(n, struct nfs_access_entry, rb_node);
2635                 rb_erase(n, root_node);
2636                 list_move(&entry->lru, head);
2637         }
2638         nfsi->cache_validity &= ~NFS_INO_INVALID_ACCESS;
2639 }
2640
2641 void nfs_access_zap_cache(struct inode *inode)
2642 {
2643         LIST_HEAD(head);
2644
2645         if (test_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags) == 0)
2646                 return;
2647         /* Remove from global LRU init */
2648         spin_lock(&nfs_access_lru_lock);
2649         if (test_and_clear_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags))
2650                 list_del_init(&NFS_I(inode)->access_cache_inode_lru);
2651
2652         spin_lock(&inode->i_lock);
2653         __nfs_access_zap_cache(NFS_I(inode), &head);
2654         spin_unlock(&inode->i_lock);
2655         spin_unlock(&nfs_access_lru_lock);
2656         nfs_access_free_list(&head);
2657 }
2658 EXPORT_SYMBOL_GPL(nfs_access_zap_cache);
2659
2660 static struct nfs_access_entry *nfs_access_search_rbtree(struct inode *inode, const struct cred *cred)
2661 {
2662         struct rb_node *n = NFS_I(inode)->access_cache.rb_node;
2663
2664         while (n != NULL) {
2665                 struct nfs_access_entry *entry =
2666                         rb_entry(n, struct nfs_access_entry, rb_node);
2667                 int cmp = cred_fscmp(cred, entry->cred);
2668
2669                 if (cmp < 0)
2670                         n = n->rb_left;
2671                 else if (cmp > 0)
2672                         n = n->rb_right;
2673                 else
2674                         return entry;
2675         }
2676         return NULL;
2677 }
2678
2679 static int nfs_access_get_cached_locked(struct inode *inode, const struct cred *cred, struct nfs_access_entry *res, bool may_block)
2680 {
2681         struct nfs_inode *nfsi = NFS_I(inode);
2682         struct nfs_access_entry *cache;
2683         bool retry = true;
2684         int err;
2685
2686         spin_lock(&inode->i_lock);
2687         for(;;) {
2688                 if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
2689                         goto out_zap;
2690                 cache = nfs_access_search_rbtree(inode, cred);
2691                 err = -ENOENT;
2692                 if (cache == NULL)
2693                         goto out;
2694                 /* Found an entry, is our attribute cache valid? */
2695                 if (!nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS))
2696                         break;
2697                 if (!retry)
2698                         break;
2699                 err = -ECHILD;
2700                 if (!may_block)
2701                         goto out;
2702                 spin_unlock(&inode->i_lock);
2703                 err = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
2704                 if (err)
2705                         return err;
2706                 spin_lock(&inode->i_lock);
2707                 retry = false;
2708         }
2709         res->cred = cache->cred;
2710         res->mask = cache->mask;
2711         list_move_tail(&cache->lru, &nfsi->access_cache_entry_lru);
2712         err = 0;
2713 out:
2714         spin_unlock(&inode->i_lock);
2715         return err;
2716 out_zap:
2717         spin_unlock(&inode->i_lock);
2718         nfs_access_zap_cache(inode);
2719         return -ENOENT;
2720 }
2721
2722 static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cred, struct nfs_access_entry *res)
2723 {
2724         /* Only check the most recently returned cache entry,
2725          * but do it without locking.
2726          */
2727         struct nfs_inode *nfsi = NFS_I(inode);
2728         struct nfs_access_entry *cache;
2729         int err = -ECHILD;
2730         struct list_head *lh;
2731
2732         rcu_read_lock();
2733         if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
2734                 goto out;
2735         lh = rcu_dereference(list_tail_rcu(&nfsi->access_cache_entry_lru));
2736         cache = list_entry(lh, struct nfs_access_entry, lru);
2737         if (lh == &nfsi->access_cache_entry_lru ||
2738             cred_fscmp(cred, cache->cred) != 0)
2739                 cache = NULL;
2740         if (cache == NULL)
2741                 goto out;
2742         if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS))
2743                 goto out;
2744         res->cred = cache->cred;
2745         res->mask = cache->mask;
2746         err = 0;
2747 out:
2748         rcu_read_unlock();
2749         return err;
2750 }
2751
2752 int nfs_access_get_cached(struct inode *inode, const struct cred *cred, struct
2753 nfs_access_entry *res, bool may_block)
2754 {
2755         int status;
2756
2757         status = nfs_access_get_cached_rcu(inode, cred, res);
2758         if (status != 0)
2759                 status = nfs_access_get_cached_locked(inode, cred, res,
2760                     may_block);
2761
2762         return status;
2763 }
2764 EXPORT_SYMBOL_GPL(nfs_access_get_cached);
2765
2766 static void nfs_access_add_rbtree(struct inode *inode, struct nfs_access_entry *set)
2767 {
2768         struct nfs_inode *nfsi = NFS_I(inode);
2769         struct rb_root *root_node = &nfsi->access_cache;
2770         struct rb_node **p = &root_node->rb_node;
2771         struct rb_node *parent = NULL;
2772         struct nfs_access_entry *entry;
2773         int cmp;
2774
2775         spin_lock(&inode->i_lock);
2776         while (*p != NULL) {
2777                 parent = *p;
2778                 entry = rb_entry(parent, struct nfs_access_entry, rb_node);
2779                 cmp = cred_fscmp(set->cred, entry->cred);
2780
2781                 if (cmp < 0)
2782                         p = &parent->rb_left;
2783                 else if (cmp > 0)
2784                         p = &parent->rb_right;
2785                 else
2786                         goto found;
2787         }
2788         rb_link_node(&set->rb_node, parent, p);
2789         rb_insert_color(&set->rb_node, root_node);
2790         list_add_tail(&set->lru, &nfsi->access_cache_entry_lru);
2791         spin_unlock(&inode->i_lock);
2792         return;
2793 found:
2794         rb_replace_node(parent, &set->rb_node, root_node);
2795         list_add_tail(&set->lru, &nfsi->access_cache_entry_lru);
2796         list_del(&entry->lru);
2797         spin_unlock(&inode->i_lock);
2798         nfs_access_free_entry(entry);
2799 }
2800
2801 void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set)
2802 {
2803         struct nfs_access_entry *cache = kmalloc(sizeof(*cache), GFP_KERNEL);
2804         if (cache == NULL)
2805                 return;
2806         RB_CLEAR_NODE(&cache->rb_node);
2807         cache->cred = get_cred(set->cred);
2808         cache->mask = set->mask;
2809
2810         /* The above field assignments must be visible
2811          * before this item appears on the lru.  We cannot easily
2812          * use rcu_assign_pointer, so just force the memory barrier.
2813          */
2814         smp_wmb();
2815         nfs_access_add_rbtree(inode, cache);
2816
2817         /* Update accounting */
2818         smp_mb__before_atomic();
2819         atomic_long_inc(&nfs_access_nr_entries);
2820         smp_mb__after_atomic();
2821
2822         /* Add inode to global LRU list */
2823         if (!test_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags)) {
2824                 spin_lock(&nfs_access_lru_lock);
2825                 if (!test_and_set_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags))
2826                         list_add_tail(&NFS_I(inode)->access_cache_inode_lru,
2827                                         &nfs_access_lru_list);
2828                 spin_unlock(&nfs_access_lru_lock);
2829         }
2830         nfs_access_cache_enforce_limit();
2831 }
2832 EXPORT_SYMBOL_GPL(nfs_access_add_cache);
2833
2834 #define NFS_MAY_READ (NFS_ACCESS_READ)
2835 #define NFS_MAY_WRITE (NFS_ACCESS_MODIFY | \
2836                 NFS_ACCESS_EXTEND | \
2837                 NFS_ACCESS_DELETE)
2838 #define NFS_FILE_MAY_WRITE (NFS_ACCESS_MODIFY | \
2839                 NFS_ACCESS_EXTEND)
2840 #define NFS_DIR_MAY_WRITE NFS_MAY_WRITE
2841 #define NFS_MAY_LOOKUP (NFS_ACCESS_LOOKUP)
2842 #define NFS_MAY_EXECUTE (NFS_ACCESS_EXECUTE)
2843 static int
2844 nfs_access_calc_mask(u32 access_result, umode_t umode)
2845 {
2846         int mask = 0;
2847
2848         if (access_result & NFS_MAY_READ)
2849                 mask |= MAY_READ;
2850         if (S_ISDIR(umode)) {
2851                 if ((access_result & NFS_DIR_MAY_WRITE) == NFS_DIR_MAY_WRITE)
2852                         mask |= MAY_WRITE;
2853                 if ((access_result & NFS_MAY_LOOKUP) == NFS_MAY_LOOKUP)
2854                         mask |= MAY_EXEC;
2855         } else if (S_ISREG(umode)) {
2856                 if ((access_result & NFS_FILE_MAY_WRITE) == NFS_FILE_MAY_WRITE)
2857                         mask |= MAY_WRITE;
2858                 if ((access_result & NFS_MAY_EXECUTE) == NFS_MAY_EXECUTE)
2859                         mask |= MAY_EXEC;
2860         } else if (access_result & NFS_MAY_WRITE)
2861                         mask |= MAY_WRITE;
2862         return mask;
2863 }
2864
2865 void nfs_access_set_mask(struct nfs_access_entry *entry, u32 access_result)
2866 {
2867         entry->mask = access_result;
2868 }
2869 EXPORT_SYMBOL_GPL(nfs_access_set_mask);
2870
2871 static int nfs_do_access(struct inode *inode, const struct cred *cred, int mask)
2872 {
2873         struct nfs_access_entry cache;
2874         bool may_block = (mask & MAY_NOT_BLOCK) == 0;
2875         int cache_mask = -1;
2876         int status;
2877
2878         trace_nfs_access_enter(inode);
2879
2880         status = nfs_access_get_cached(inode, cred, &cache, may_block);
2881         if (status == 0)
2882                 goto out_cached;
2883
2884         status = -ECHILD;
2885         if (!may_block)
2886                 goto out;
2887
2888         /*
2889          * Determine which access bits we want to ask for...
2890          */
2891         cache.mask = NFS_ACCESS_READ | NFS_ACCESS_MODIFY | NFS_ACCESS_EXTEND;
2892         if (nfs_server_capable(inode, NFS_CAP_XATTR)) {
2893                 cache.mask |= NFS_ACCESS_XAREAD | NFS_ACCESS_XAWRITE |
2894                     NFS_ACCESS_XALIST;
2895         }
2896         if (S_ISDIR(inode->i_mode))
2897                 cache.mask |= NFS_ACCESS_DELETE | NFS_ACCESS_LOOKUP;
2898         else
2899                 cache.mask |= NFS_ACCESS_EXECUTE;
2900         cache.cred = cred;
2901         status = NFS_PROTO(inode)->access(inode, &cache);
2902         if (status != 0) {
2903                 if (status == -ESTALE) {
2904                         if (!S_ISDIR(inode->i_mode))
2905                                 nfs_set_inode_stale(inode);
2906                         else
2907                                 nfs_zap_caches(inode);
2908                 }
2909                 goto out;
2910         }
2911         nfs_access_add_cache(inode, &cache);
2912 out_cached:
2913         cache_mask = nfs_access_calc_mask(cache.mask, inode->i_mode);
2914         if ((mask & ~cache_mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) != 0)
2915                 status = -EACCES;
2916 out:
2917         trace_nfs_access_exit(inode, mask, cache_mask, status);
2918         return status;
2919 }
2920
2921 static int nfs_open_permission_mask(int openflags)
2922 {
2923         int mask = 0;
2924
2925         if (openflags & __FMODE_EXEC) {
2926                 /* ONLY check exec rights */
2927                 mask = MAY_EXEC;
2928         } else {
2929                 if ((openflags & O_ACCMODE) != O_WRONLY)
2930                         mask |= MAY_READ;
2931                 if ((openflags & O_ACCMODE) != O_RDONLY)
2932                         mask |= MAY_WRITE;
2933         }
2934
2935         return mask;
2936 }
2937
2938 int nfs_may_open(struct inode *inode, const struct cred *cred, int openflags)
2939 {
2940         return nfs_do_access(inode, cred, nfs_open_permission_mask(openflags));
2941 }
2942 EXPORT_SYMBOL_GPL(nfs_may_open);
2943
2944 static int nfs_execute_ok(struct inode *inode, int mask)
2945 {
2946         struct nfs_server *server = NFS_SERVER(inode);
2947         int ret = 0;
2948
2949         if (S_ISDIR(inode->i_mode))
2950                 return 0;
2951         if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_MODE)) {
2952                 if (mask & MAY_NOT_BLOCK)
2953                         return -ECHILD;
2954                 ret = __nfs_revalidate_inode(server, inode);
2955         }
2956         if (ret == 0 && !execute_ok(inode))
2957                 ret = -EACCES;
2958         return ret;
2959 }
2960
2961 int nfs_permission(struct user_namespace *mnt_userns,
2962                    struct inode *inode,
2963                    int mask)
2964 {
2965         const struct cred *cred = current_cred();
2966         int res = 0;
2967
2968         nfs_inc_stats(inode, NFSIOS_VFSACCESS);
2969
2970         if ((mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
2971                 goto out;
2972         /* Is this sys_access() ? */
2973         if (mask & (MAY_ACCESS | MAY_CHDIR))
2974                 goto force_lookup;
2975
2976         switch (inode->i_mode & S_IFMT) {
2977                 case S_IFLNK:
2978                         goto out;
2979                 case S_IFREG:
2980                         if ((mask & MAY_OPEN) &&
2981                            nfs_server_capable(inode, NFS_CAP_ATOMIC_OPEN))
2982                                 return 0;
2983                         break;
2984                 case S_IFDIR:
2985                         /*
2986                          * Optimize away all write operations, since the server
2987                          * will check permissions when we perform the op.
2988                          */
2989                         if ((mask & MAY_WRITE) && !(mask & MAY_READ))
2990                                 goto out;
2991         }
2992
2993 force_lookup:
2994         if (!NFS_PROTO(inode)->access)
2995                 goto out_notsup;
2996
2997         res = nfs_do_access(inode, cred, mask);
2998 out:
2999         if (!res && (mask & MAY_EXEC))
3000                 res = nfs_execute_ok(inode, mask);
3001
3002         dfprintk(VFS, "NFS: permission(%s/%lu), mask=0x%x, res=%d\n",
3003                 inode->i_sb->s_id, inode->i_ino, mask, res);
3004         return res;
3005 out_notsup:
3006         if (mask & MAY_NOT_BLOCK)
3007                 return -ECHILD;
3008
3009         res = nfs_revalidate_inode(inode, NFS_INO_INVALID_MODE |
3010                                                   NFS_INO_INVALID_OTHER);
3011         if (res == 0)
3012                 res = generic_permission(&init_user_ns, inode, mask);
3013         goto out;
3014 }
3015 EXPORT_SYMBOL_GPL(nfs_permission);