fs/nfsd/filecache.c

   1 /*
   2  * Open file cache.
   3  *
   4  * (c) 2015 - Jeff Layton <jeff.layton@primarydata.com>
   5  */
   6
   7 #include <linux/hash.h>
   8 #include <linux/slab.h>
   9 #include <linux/file.h>
  10 #include <linux/pagemap.h>
  11 #include <linux/sched.h>
  12 #include <linux/list_lru.h>
  13 #include <linux/fsnotify_backend.h>
  14 #include <linux/fsnotify.h>
  15 #include <linux/seq_file.h>
  16
  17 #include "vfs.h"
  18 #include "nfsd.h"
  19 #include "nfsfh.h"
  20 #include "netns.h"
  21 #include "filecache.h"
  22 #include "trace.h"
  23
  24 #define NFSDDBG_FACILITY        NFSDDBG_FH
  25
  26 /* FIXME: dynamically size this for the machine somehow? */
  27 #define NFSD_FILE_HASH_BITS                   12
  28 #define NFSD_FILE_HASH_SIZE                  (1 << NFSD_FILE_HASH_BITS)
  29 #define NFSD_LAUNDRETTE_DELAY                (2 * HZ)
  30
  31 #define NFSD_FILE_SHUTDOWN                   (1)
  32 #define NFSD_FILE_LRU_THRESHOLD              (4096UL)
  33 #define NFSD_FILE_LRU_LIMIT                  (NFSD_FILE_LRU_THRESHOLD << 2)
  34
  35 /* We only care about NFSD_MAY_READ/WRITE for this cache */
  36 #define NFSD_FILE_MAY_MASK      (NFSD_MAY_READ|NFSD_MAY_WRITE)
  37
  38 struct nfsd_fcache_bucket {
  39         struct hlist_head       nfb_head;
  40         spinlock_t              nfb_lock;
  41         unsigned int            nfb_count;
  42         unsigned int            nfb_maxcount;
  43 };
  44
  45 static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits);
  46
  47 struct nfsd_fcache_disposal {
  48         struct work_struct work;
  49         spinlock_t lock;
  50         struct list_head freeme;
  51 };
  52
  53 static struct workqueue_struct *nfsd_filecache_wq __read_mostly;
  54
  55 static struct kmem_cache                *nfsd_file_slab;
  56 static struct kmem_cache                *nfsd_file_mark_slab;
  57 static struct nfsd_fcache_bucket        *nfsd_file_hashtbl;
  58 static struct list_lru                  nfsd_file_lru;
  59 static long                             nfsd_file_lru_flags;
  60 static struct fsnotify_group            *nfsd_file_fsnotify_group;
  61 static atomic_long_t                    nfsd_filecache_count;
  62 static struct delayed_work              nfsd_filecache_laundrette;
  63
  64 static void nfsd_file_gc(void);
  65
  66 static void
  67 nfsd_file_schedule_laundrette(void)
  68 {
  69         long count = atomic_long_read(&nfsd_filecache_count);
  70
  71         if (count == 0 || test_bit(NFSD_FILE_SHUTDOWN, &nfsd_file_lru_flags))
  72                 return;
  73
  74         queue_delayed_work(system_wq, &nfsd_filecache_laundrette,
  75                         NFSD_LAUNDRETTE_DELAY);
  76 }
  77
  78 static void
  79 nfsd_file_slab_free(struct rcu_head *rcu)
  80 {
  81         struct nfsd_file *nf = container_of(rcu, struct nfsd_file, nf_rcu);
  82
  83         put_cred(nf->nf_cred);
  84         kmem_cache_free(nfsd_file_slab, nf);
  85 }
  86
  87 static void
  88 nfsd_file_mark_free(struct fsnotify_mark *mark)
  89 {
  90         struct nfsd_file_mark *nfm = container_of(mark, struct nfsd_file_mark,
  91                                                   nfm_mark);
  92
  93         kmem_cache_free(nfsd_file_mark_slab, nfm);
  94 }
  95
  96 static struct nfsd_file_mark *
  97 nfsd_file_mark_get(struct nfsd_file_mark *nfm)
  98 {
  99         if (!refcount_inc_not_zero(&nfm->nfm_ref))
 100                 return NULL;
 101         return nfm;
 102 }
 103
 104 static void
 105 nfsd_file_mark_put(struct nfsd_file_mark *nfm)
 106 {
 107         if (refcount_dec_and_test(&nfm->nfm_ref)) {
 108                 fsnotify_destroy_mark(&nfm->nfm_mark, nfsd_file_fsnotify_group);
 109                 fsnotify_put_mark(&nfm->nfm_mark);
 110         }
 111 }
 112
 113 static struct nfsd_file_mark *
 114 nfsd_file_mark_find_or_create(struct nfsd_file *nf)
 115 {
 116         int                     err;
 117         struct fsnotify_mark    *mark;
 118         struct nfsd_file_mark   *nfm = NULL, *new;
 119         struct inode *inode = nf->nf_inode;
 120
 121         do {
 122                 fsnotify_group_lock(nfsd_file_fsnotify_group);
 123                 mark = fsnotify_find_mark(&inode->i_fsnotify_marks,
 124                                           nfsd_file_fsnotify_group);
 125                 if (mark) {
 126                         nfm = nfsd_file_mark_get(container_of(mark,
 127                                                  struct nfsd_file_mark,
 128                                                  nfm_mark));
 129                         fsnotify_group_unlock(nfsd_file_fsnotify_group);
 130                         if (nfm) {
 131                                 fsnotify_put_mark(mark);
 132                                 break;
 133                         }
 134                         /* Avoid soft lockup race with nfsd_file_mark_put() */
 135                         fsnotify_destroy_mark(mark, nfsd_file_fsnotify_group);
 136                         fsnotify_put_mark(mark);
 137                 } else {
 138                         fsnotify_group_unlock(nfsd_file_fsnotify_group);
 139                 }
 140
 141                 /* allocate a new nfm */
 142                 new = kmem_cache_alloc(nfsd_file_mark_slab, GFP_KERNEL);
 143                 if (!new)
 144                         return NULL;
 145                 fsnotify_init_mark(&new->nfm_mark, nfsd_file_fsnotify_group);
 146                 new->nfm_mark.mask = FS_ATTRIB|FS_DELETE_SELF;
 147                 refcount_set(&new->nfm_ref, 1);
 148
 149                 err = fsnotify_add_inode_mark(&new->nfm_mark, inode, 0);
 150
 151                 /*
 152                  * If the add was successful, then return the object.
 153                  * Otherwise, we need to put the reference we hold on the
 154                  * nfm_mark. The fsnotify code will take a reference and put
 155                  * it on failure, so we can't just free it directly. It's also
 156                  * not safe to call fsnotify_destroy_mark on it as the
 157                  * mark->group will be NULL. Thus, we can't let the nfm_ref
 158                  * counter drive the destruction at this point.
 159                  */
 160                 if (likely(!err))
 161                         nfm = new;
 162                 else
 163                         fsnotify_put_mark(&new->nfm_mark);
 164         } while (unlikely(err == -EEXIST));
 165
 166         return nfm;
 167 }
 168
 169 static struct nfsd_file *
 170 nfsd_file_alloc(struct inode *inode, unsigned int may, unsigned int hashval,
 171                 struct net *net)
 172 {
 173         struct nfsd_file *nf;
 174
 175         nf = kmem_cache_alloc(nfsd_file_slab, GFP_KERNEL);
 176         if (nf) {
 177                 INIT_HLIST_NODE(&nf->nf_node);
 178                 INIT_LIST_HEAD(&nf->nf_lru);
 179                 nf->nf_file = NULL;
 180                 nf->nf_cred = get_current_cred();
 181                 nf->nf_net = net;
 182                 nf->nf_flags = 0;
 183                 nf->nf_inode = inode;
 184                 nf->nf_hashval = hashval;
 185                 refcount_set(&nf->nf_ref, 1);
 186                 nf->nf_may = may & NFSD_FILE_MAY_MASK;
 187                 if (may & NFSD_MAY_NOT_BREAK_LEASE) {
 188                         if (may & NFSD_MAY_WRITE)
 189                                 __set_bit(NFSD_FILE_BREAK_WRITE, &nf->nf_flags);
 190                         if (may & NFSD_MAY_READ)
 191                                 __set_bit(NFSD_FILE_BREAK_READ, &nf->nf_flags);
 192                 }
 193                 nf->nf_mark = NULL;
 194                 trace_nfsd_file_alloc(nf);
 195         }
 196         return nf;
 197 }
 198
 199 static bool
 200 nfsd_file_free(struct nfsd_file *nf)
 201 {
 202         bool flush = false;
 203
 204         trace_nfsd_file_put_final(nf);
 205         if (nf->nf_mark)
 206                 nfsd_file_mark_put(nf->nf_mark);
 207         if (nf->nf_file) {
 208                 get_file(nf->nf_file);
 209                 filp_close(nf->nf_file, NULL);
 210                 fput(nf->nf_file);
 211                 flush = true;
 212         }
 213         call_rcu(&nf->nf_rcu, nfsd_file_slab_free);
 214         return flush;
 215 }
 216
 217 static bool
 218 nfsd_file_check_writeback(struct nfsd_file *nf)
 219 {
 220         struct file *file = nf->nf_file;
 221         struct address_space *mapping;
 222
 223         if (!file || !(file->f_mode & FMODE_WRITE))
 224                 return false;
 225         mapping = file->f_mapping;
 226         return mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) ||
 227                 mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK);
 228 }
 229
 230 static int
 231 nfsd_file_check_write_error(struct nfsd_file *nf)
 232 {
 233         struct file *file = nf->nf_file;
 234
 235         if (!file || !(file->f_mode & FMODE_WRITE))
 236                 return 0;
 237         return filemap_check_wb_err(file->f_mapping, READ_ONCE(file->f_wb_err));
 238 }
 239
 240 static void
 241 nfsd_file_flush(struct nfsd_file *nf)
 242 {
 243         if (nf->nf_file && vfs_fsync(nf->nf_file, 1) != 0)
 244                 nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id));
 245 }
 246
 247 static void
 248 nfsd_file_do_unhash(struct nfsd_file *nf)
 249 {
 250         lockdep_assert_held(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
 251
 252         trace_nfsd_file_unhash(nf);
 253
 254         if (nfsd_file_check_write_error(nf))
 255                 nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id));
 256         --nfsd_file_hashtbl[nf->nf_hashval].nfb_count;
 257         hlist_del_rcu(&nf->nf_node);
 258         atomic_long_dec(&nfsd_filecache_count);
 259 }
 260
 261 static bool
 262 nfsd_file_unhash(struct nfsd_file *nf)
 263 {
 264         if (test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
 265                 nfsd_file_do_unhash(nf);
 266                 if (!list_empty(&nf->nf_lru))
 267                         list_lru_del(&nfsd_file_lru, &nf->nf_lru);
 268                 return true;
 269         }
 270         return false;
 271 }
 272
 273 /*
 274  * Return true if the file was unhashed.
 275  */
 276 static bool
 277 nfsd_file_unhash_and_release_locked(struct nfsd_file *nf, struct list_head *dispose)
 278 {
 279         lockdep_assert_held(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
 280
 281         trace_nfsd_file_unhash_and_release_locked(nf);
 282         if (!nfsd_file_unhash(nf))
 283                 return false;
 284         /* keep final reference for nfsd_file_lru_dispose */
 285         if (refcount_dec_not_one(&nf->nf_ref))
 286                 return true;
 287
 288         list_add(&nf->nf_lru, dispose);
 289         return true;
 290 }
 291
 292 static void
 293 nfsd_file_put_noref(struct nfsd_file *nf)
 294 {
 295         trace_nfsd_file_put(nf);
 296
 297         if (refcount_dec_and_test(&nf->nf_ref)) {
 298                 WARN_ON(test_bit(NFSD_FILE_HASHED, &nf->nf_flags));
 299                 nfsd_file_free(nf);
 300         }
 301 }
 302
 303 void
 304 nfsd_file_put(struct nfsd_file *nf)
 305 {
 306         might_sleep();
 307
 308         set_bit(NFSD_FILE_REFERENCED, &nf->nf_flags);
 309         if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags) == 0) {
 310                 nfsd_file_flush(nf);
 311                 nfsd_file_put_noref(nf);
 312         } else if (nf->nf_file) {
 313                 nfsd_file_put_noref(nf);
 314                 nfsd_file_schedule_laundrette();
 315         } else
 316                 nfsd_file_put_noref(nf);
 317
 318         if (atomic_long_read(&nfsd_filecache_count) >= NFSD_FILE_LRU_LIMIT)
 319                 nfsd_file_gc();
 320 }
 321
 322 struct nfsd_file *
 323 nfsd_file_get(struct nfsd_file *nf)
 324 {
 325         if (likely(refcount_inc_not_zero(&nf->nf_ref)))
 326                 return nf;
 327         return NULL;
 328 }
 329
 330 static void
 331 nfsd_file_dispose_list(struct list_head *dispose)
 332 {
 333         struct nfsd_file *nf;
 334
 335         while(!list_empty(dispose)) {
 336                 nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
 337                 list_del(&nf->nf_lru);
 338                 nfsd_file_flush(nf);
 339                 nfsd_file_put_noref(nf);
 340         }
 341 }
 342
 343 static void
 344 nfsd_file_dispose_list_sync(struct list_head *dispose)
 345 {
 346         bool flush = false;
 347         struct nfsd_file *nf;
 348
 349         while(!list_empty(dispose)) {
 350                 nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
 351                 list_del(&nf->nf_lru);
 352                 nfsd_file_flush(nf);
 353                 if (!refcount_dec_and_test(&nf->nf_ref))
 354                         continue;
 355                 if (nfsd_file_free(nf))
 356                         flush = true;
 357         }
 358         if (flush)
 359                 flush_delayed_fput();
 360 }
 361
 362 static void
 363 nfsd_file_list_remove_disposal(struct list_head *dst,
 364                 struct nfsd_fcache_disposal *l)
 365 {
 366         spin_lock(&l->lock);
 367         list_splice_init(&l->freeme, dst);
 368         spin_unlock(&l->lock);
 369 }
 370
 371 static void
 372 nfsd_file_list_add_disposal(struct list_head *files, struct net *net)
 373 {
 374         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 375         struct nfsd_fcache_disposal *l = nn->fcache_disposal;
 376
 377         spin_lock(&l->lock);
 378         list_splice_tail_init(files, &l->freeme);
 379         spin_unlock(&l->lock);
 380         queue_work(nfsd_filecache_wq, &l->work);
 381 }
 382
 383 static void
 384 nfsd_file_list_add_pernet(struct list_head *dst, struct list_head *src,
 385                 struct net *net)
 386 {
 387         struct nfsd_file *nf, *tmp;
 388
 389         list_for_each_entry_safe(nf, tmp, src, nf_lru) {
 390                 if (nf->nf_net == net)
 391                         list_move_tail(&nf->nf_lru, dst);
 392         }
 393 }
 394
 395 static void
 396 nfsd_file_dispose_list_delayed(struct list_head *dispose)
 397 {
 398         LIST_HEAD(list);
 399         struct nfsd_file *nf;
 400
 401         while(!list_empty(dispose)) {
 402                 nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
 403                 nfsd_file_list_add_pernet(&list, dispose, nf->nf_net);
 404                 nfsd_file_list_add_disposal(&list, nf->nf_net);
 405         }
 406 }
 407
 408 /*
 409  * Note this can deadlock with nfsd_file_cache_purge.
 410  */
 411 static enum lru_status
 412 nfsd_file_lru_cb(struct list_head *item, struct list_lru_one *lru,
 413                  spinlock_t *lock, void *arg)
 414         __releases(lock)
 415         __acquires(lock)
 416 {
 417         struct list_head *head = arg;
 418         struct nfsd_file *nf = list_entry(item, struct nfsd_file, nf_lru);
 419
 420         /*
 421          * Do a lockless refcount check. The hashtable holds one reference, so
 422          * we look to see if anything else has a reference, or if any have
 423          * been put since the shrinker last ran. Those don't get unhashed and
 424          * released.
 425          *
 426          * Note that in the put path, we set the flag and then decrement the
 427          * counter. Here we check the counter and then test and clear the flag.
 428          * That order is deliberate to ensure that we can do this locklessly.
 429          */
 430         if (refcount_read(&nf->nf_ref) > 1)
 431                 goto out_skip;
 432
 433         /*
 434          * Don't throw out files that are still undergoing I/O or
 435          * that have uncleared errors pending.
 436          */
 437         if (nfsd_file_check_writeback(nf))
 438                 goto out_skip;
 439
 440         if (test_and_clear_bit(NFSD_FILE_REFERENCED, &nf->nf_flags))
 441                 goto out_skip;
 442
 443         if (!test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags))
 444                 goto out_skip;
 445
 446         list_lru_isolate_move(lru, &nf->nf_lru, head);
 447         return LRU_REMOVED;
 448 out_skip:
 449         return LRU_SKIP;
 450 }
 451
 452 static unsigned long
 453 nfsd_file_lru_walk_list(struct shrink_control *sc)
 454 {
 455         LIST_HEAD(head);
 456         struct nfsd_file *nf;
 457         unsigned long ret;
 458
 459         if (sc)
 460                 ret = list_lru_shrink_walk(&nfsd_file_lru, sc,
 461                                 nfsd_file_lru_cb, &head);
 462         else
 463                 ret = list_lru_walk(&nfsd_file_lru,
 464                                 nfsd_file_lru_cb,
 465                                 &head, LONG_MAX);
 466         list_for_each_entry(nf, &head, nf_lru) {
 467                 spin_lock(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
 468                 nfsd_file_do_unhash(nf);
 469                 spin_unlock(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
 470         }
 471         nfsd_file_dispose_list_delayed(&head);
 472         return ret;
 473 }
 474
 475 static void
 476 nfsd_file_gc(void)
 477 {
 478         nfsd_file_lru_walk_list(NULL);
 479 }
 480
 481 static void
 482 nfsd_file_gc_worker(struct work_struct *work)
 483 {
 484         nfsd_file_gc();
 485         nfsd_file_schedule_laundrette();
 486 }
 487
 488 static unsigned long
 489 nfsd_file_lru_count(struct shrinker *s, struct shrink_control *sc)
 490 {
 491         return list_lru_count(&nfsd_file_lru);
 492 }
 493
 494 static unsigned long
 495 nfsd_file_lru_scan(struct shrinker *s, struct shrink_control *sc)
 496 {
 497         return nfsd_file_lru_walk_list(sc);
 498 }
 499
 500 static struct shrinker  nfsd_file_shrinker = {
 501         .scan_objects = nfsd_file_lru_scan,
 502         .count_objects = nfsd_file_lru_count,
 503         .seeks = 1,
 504 };
 505
 506 static void
 507 __nfsd_file_close_inode(struct inode *inode, unsigned int hashval,
 508                         struct list_head *dispose)
 509 {
 510         struct nfsd_file        *nf;
 511         struct hlist_node       *tmp;
 512
 513         spin_lock(&nfsd_file_hashtbl[hashval].nfb_lock);
 514         hlist_for_each_entry_safe(nf, tmp, &nfsd_file_hashtbl[hashval].nfb_head, nf_node) {
 515                 if (inode == nf->nf_inode)
 516                         nfsd_file_unhash_and_release_locked(nf, dispose);
 517         }
 518         spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
 519 }
 520
 521 /**
 522  * nfsd_file_close_inode_sync - attempt to forcibly close a nfsd_file
 523  * @inode: inode of the file to attempt to remove
 524  *
 525  * Walk the whole hash bucket, looking for any files that correspond to "inode".
 526  * If any do, then unhash them and put the hashtable reference to them and
 527  * destroy any that had their last reference put. Also ensure that any of the
 528  * fputs also have their final __fput done as well.
 529  */
 530 void
 531 nfsd_file_close_inode_sync(struct inode *inode)
 532 {
 533         unsigned int            hashval = (unsigned int)hash_long(inode->i_ino,
 534                                                 NFSD_FILE_HASH_BITS);
 535         LIST_HEAD(dispose);
 536
 537         __nfsd_file_close_inode(inode, hashval, &dispose);
 538         trace_nfsd_file_close_inode_sync(inode, hashval, !list_empty(&dispose));
 539         nfsd_file_dispose_list_sync(&dispose);
 540 }
 541
 542 /**
 543  * nfsd_file_close_inode - attempt a delayed close of a nfsd_file
 544  * @inode: inode of the file to attempt to remove
 545  *
 546  * Walk the whole hash bucket, looking for any files that correspond to "inode".
 547  * If any do, then unhash them and put the hashtable reference to them and
 548  * destroy any that had their last reference put.
 549  */
 550 static void
 551 nfsd_file_close_inode(struct inode *inode)
 552 {
 553         unsigned int            hashval = (unsigned int)hash_long(inode->i_ino,
 554                                                 NFSD_FILE_HASH_BITS);
 555         LIST_HEAD(dispose);
 556
 557         __nfsd_file_close_inode(inode, hashval, &dispose);
 558         trace_nfsd_file_close_inode(inode, hashval, !list_empty(&dispose));
 559         nfsd_file_dispose_list_delayed(&dispose);
 560 }
 561
 562 /**
 563  * nfsd_file_delayed_close - close unused nfsd_files
 564  * @work: dummy
 565  *
 566  * Walk the LRU list and close any entries that have not been used since
 567  * the last scan.
 568  *
 569  * Note this can deadlock with nfsd_file_cache_purge.
 570  */
 571 static void
 572 nfsd_file_delayed_close(struct work_struct *work)
 573 {
 574         LIST_HEAD(head);
 575         struct nfsd_fcache_disposal *l = container_of(work,
 576                         struct nfsd_fcache_disposal, work);
 577
 578         nfsd_file_list_remove_disposal(&head, l);
 579         nfsd_file_dispose_list(&head);
 580 }
 581
 582 static int
 583 nfsd_file_lease_notifier_call(struct notifier_block *nb, unsigned long arg,
 584                             void *data)
 585 {
 586         struct file_lock *fl = data;
 587
 588         /* Only close files for F_SETLEASE leases */
 589         if (fl->fl_flags & FL_LEASE)
 590                 nfsd_file_close_inode_sync(file_inode(fl->fl_file));
 591         return 0;
 592 }
 593
 594 static struct notifier_block nfsd_file_lease_notifier = {
 595         .notifier_call = nfsd_file_lease_notifier_call,
 596 };
 597
 598 static int
 599 nfsd_file_fsnotify_handle_event(struct fsnotify_mark *mark, u32 mask,
 600                                 struct inode *inode, struct inode *dir,
 601                                 const struct qstr *name, u32 cookie)
 602 {
 603         if (WARN_ON_ONCE(!inode))
 604                 return 0;
 605
 606         trace_nfsd_file_fsnotify_handle_event(inode, mask);
 607
 608         /* Should be no marks on non-regular files */
 609         if (!S_ISREG(inode->i_mode)) {
 610                 WARN_ON_ONCE(1);
 611                 return 0;
 612         }
 613
 614         /* don't close files if this was not the last link */
 615         if (mask & FS_ATTRIB) {
 616                 if (inode->i_nlink)
 617                         return 0;
 618         }
 619
 620         nfsd_file_close_inode(inode);
 621         return 0;
 622 }
 623
 624
 625 static const struct fsnotify_ops nfsd_file_fsnotify_ops = {
 626         .handle_inode_event = nfsd_file_fsnotify_handle_event,
 627         .free_mark = nfsd_file_mark_free,
 628 };
 629
 630 int
 631 nfsd_file_cache_init(void)
 632 {
 633         int             ret = -ENOMEM;
 634         unsigned int    i;
 635
 636         clear_bit(NFSD_FILE_SHUTDOWN, &nfsd_file_lru_flags);
 637
 638         if (nfsd_file_hashtbl)
 639                 return 0;
 640
 641         nfsd_filecache_wq = alloc_workqueue("nfsd_filecache", 0, 0);
 642         if (!nfsd_filecache_wq)
 643                 goto out;
 644
 645         nfsd_file_hashtbl = kvcalloc(NFSD_FILE_HASH_SIZE,
 646                                 sizeof(*nfsd_file_hashtbl), GFP_KERNEL);
 647         if (!nfsd_file_hashtbl) {
 648                 pr_err("nfsd: unable to allocate nfsd_file_hashtbl\n");
 649                 goto out_err;
 650         }
 651
 652         nfsd_file_slab = kmem_cache_create("nfsd_file",
 653                                 sizeof(struct nfsd_file), 0, 0, NULL);
 654         if (!nfsd_file_slab) {
 655                 pr_err("nfsd: unable to create nfsd_file_slab\n");
 656                 goto out_err;
 657         }
 658
 659         nfsd_file_mark_slab = kmem_cache_create("nfsd_file_mark",
 660                                         sizeof(struct nfsd_file_mark), 0, 0, NULL);
 661         if (!nfsd_file_mark_slab) {
 662                 pr_err("nfsd: unable to create nfsd_file_mark_slab\n");
 663                 goto out_err;
 664         }
 665
 666
 667         ret = list_lru_init(&nfsd_file_lru);
 668         if (ret) {
 669                 pr_err("nfsd: failed to init nfsd_file_lru: %d\n", ret);
 670                 goto out_err;
 671         }
 672
 673         ret = register_shrinker(&nfsd_file_shrinker);
 674         if (ret) {
 675                 pr_err("nfsd: failed to register nfsd_file_shrinker: %d\n", ret);
 676                 goto out_lru;
 677         }
 678
 679         ret = lease_register_notifier(&nfsd_file_lease_notifier);
 680         if (ret) {
 681                 pr_err("nfsd: unable to register lease notifier: %d\n", ret);
 682                 goto out_shrinker;
 683         }
 684
 685         nfsd_file_fsnotify_group = fsnotify_alloc_group(&nfsd_file_fsnotify_ops,
 686                                                         FSNOTIFY_GROUP_NOFS);
 687         if (IS_ERR(nfsd_file_fsnotify_group)) {
 688                 pr_err("nfsd: unable to create fsnotify group: %ld\n",
 689                         PTR_ERR(nfsd_file_fsnotify_group));
 690                 ret = PTR_ERR(nfsd_file_fsnotify_group);
 691                 nfsd_file_fsnotify_group = NULL;
 692                 goto out_notifier;
 693         }
 694
 695         for (i = 0; i < NFSD_FILE_HASH_SIZE; i++) {
 696                 INIT_HLIST_HEAD(&nfsd_file_hashtbl[i].nfb_head);
 697                 spin_lock_init(&nfsd_file_hashtbl[i].nfb_lock);
 698         }
 699
 700         INIT_DELAYED_WORK(&nfsd_filecache_laundrette, nfsd_file_gc_worker);
 701 out:
 702         return ret;
 703 out_notifier:
 704         lease_unregister_notifier(&nfsd_file_lease_notifier);
 705 out_shrinker:
 706         unregister_shrinker(&nfsd_file_shrinker);
 707 out_lru:
 708         list_lru_destroy(&nfsd_file_lru);
 709 out_err:
 710         kmem_cache_destroy(nfsd_file_slab);
 711         nfsd_file_slab = NULL;
 712         kmem_cache_destroy(nfsd_file_mark_slab);
 713         nfsd_file_mark_slab = NULL;
 714         kvfree(nfsd_file_hashtbl);
 715         nfsd_file_hashtbl = NULL;
 716         destroy_workqueue(nfsd_filecache_wq);
 717         nfsd_filecache_wq = NULL;
 718         goto out;
 719 }
 720
 721 /*
 722  * Note this can deadlock with nfsd_file_lru_cb.
 723  */
 724 void
 725 nfsd_file_cache_purge(struct net *net)
 726 {
 727         unsigned int            i;
 728         struct nfsd_file        *nf;
 729         struct hlist_node       *next;
 730         LIST_HEAD(dispose);
 731         bool del;
 732
 733         if (!nfsd_file_hashtbl)
 734                 return;
 735
 736         for (i = 0; i < NFSD_FILE_HASH_SIZE; i++) {
 737                 struct nfsd_fcache_bucket *nfb = &nfsd_file_hashtbl[i];
 738
 739                 spin_lock(&nfb->nfb_lock);
 740                 hlist_for_each_entry_safe(nf, next, &nfb->nfb_head, nf_node) {
 741                         if (net && nf->nf_net != net)
 742                                 continue;
 743                         del = nfsd_file_unhash_and_release_locked(nf, &dispose);
 744
 745                         /*
 746                          * Deadlock detected! Something marked this entry as
 747                          * unhased, but hasn't removed it from the hash list.
 748                          */
 749                         WARN_ON_ONCE(!del);
 750                 }
 751                 spin_unlock(&nfb->nfb_lock);
 752                 nfsd_file_dispose_list(&dispose);
 753         }
 754 }
 755
 756 static struct nfsd_fcache_disposal *
 757 nfsd_alloc_fcache_disposal(void)
 758 {
 759         struct nfsd_fcache_disposal *l;
 760
 761         l = kmalloc(sizeof(*l), GFP_KERNEL);
 762         if (!l)
 763                 return NULL;
 764         INIT_WORK(&l->work, nfsd_file_delayed_close);
 765         spin_lock_init(&l->lock);
 766         INIT_LIST_HEAD(&l->freeme);
 767         return l;
 768 }
 769
 770 static void
 771 nfsd_free_fcache_disposal(struct nfsd_fcache_disposal *l)
 772 {
 773         cancel_work_sync(&l->work);
 774         nfsd_file_dispose_list(&l->freeme);
 775         kfree(l);
 776 }
 777
 778 static void
 779 nfsd_free_fcache_disposal_net(struct net *net)
 780 {
 781         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 782         struct nfsd_fcache_disposal *l = nn->fcache_disposal;
 783
 784         nfsd_free_fcache_disposal(l);
 785 }
 786
 787 int
 788 nfsd_file_cache_start_net(struct net *net)
 789 {
 790         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 791
 792         nn->fcache_disposal = nfsd_alloc_fcache_disposal();
 793         return nn->fcache_disposal ? 0 : -ENOMEM;
 794 }
 795
 796 void
 797 nfsd_file_cache_shutdown_net(struct net *net)
 798 {
 799         nfsd_file_cache_purge(net);
 800         nfsd_free_fcache_disposal_net(net);
 801 }
 802
 803 void
 804 nfsd_file_cache_shutdown(void)
 805 {
 806         set_bit(NFSD_FILE_SHUTDOWN, &nfsd_file_lru_flags);
 807
 808         lease_unregister_notifier(&nfsd_file_lease_notifier);
 809         unregister_shrinker(&nfsd_file_shrinker);
 810         /*
 811          * make sure all callers of nfsd_file_lru_cb are done before
 812          * calling nfsd_file_cache_purge
 813          */
 814         cancel_delayed_work_sync(&nfsd_filecache_laundrette);
 815         nfsd_file_cache_purge(NULL);
 816         list_lru_destroy(&nfsd_file_lru);
 817         rcu_barrier();
 818         fsnotify_put_group(nfsd_file_fsnotify_group);
 819         nfsd_file_fsnotify_group = NULL;
 820         kmem_cache_destroy(nfsd_file_slab);
 821         nfsd_file_slab = NULL;
 822         fsnotify_wait_marks_destroyed();
 823         kmem_cache_destroy(nfsd_file_mark_slab);
 824         nfsd_file_mark_slab = NULL;
 825         kvfree(nfsd_file_hashtbl);
 826         nfsd_file_hashtbl = NULL;
 827         destroy_workqueue(nfsd_filecache_wq);
 828         nfsd_filecache_wq = NULL;
 829 }
 830
 831 static bool
 832 nfsd_match_cred(const struct cred *c1, const struct cred *c2)
 833 {
 834         int i;
 835
 836         if (!uid_eq(c1->fsuid, c2->fsuid))
 837                 return false;
 838         if (!gid_eq(c1->fsgid, c2->fsgid))
 839                 return false;
 840         if (c1->group_info == NULL || c2->group_info == NULL)
 841                 return c1->group_info == c2->group_info;
 842         if (c1->group_info->ngroups != c2->group_info->ngroups)
 843                 return false;
 844         for (i = 0; i < c1->group_info->ngroups; i++) {
 845                 if (!gid_eq(c1->group_info->gid[i], c2->group_info->gid[i]))
 846                         return false;
 847         }
 848         return true;
 849 }
 850
 851 static struct nfsd_file *
 852 nfsd_file_find_locked(struct inode *inode, unsigned int may_flags,
 853                         unsigned int hashval, struct net *net)
 854 {
 855         struct nfsd_file *nf;
 856         unsigned char need = may_flags & NFSD_FILE_MAY_MASK;
 857
 858         hlist_for_each_entry_rcu(nf, &nfsd_file_hashtbl[hashval].nfb_head,
 859                                  nf_node, lockdep_is_held(&nfsd_file_hashtbl[hashval].nfb_lock)) {
 860                 if (nf->nf_may != need)
 861                         continue;
 862                 if (nf->nf_inode != inode)
 863                         continue;
 864                 if (nf->nf_net != net)
 865                         continue;
 866                 if (!nfsd_match_cred(nf->nf_cred, current_cred()))
 867                         continue;
 868                 if (!test_bit(NFSD_FILE_HASHED, &nf->nf_flags))
 869                         continue;
 870                 if (nfsd_file_get(nf) != NULL)
 871                         return nf;
 872         }
 873         return NULL;
 874 }
 875
 876 /**
 877  * nfsd_file_is_cached - are there any cached open files for this fh?
 878  * @inode: inode of the file to check
 879  *
 880  * Scan the hashtable for open files that match this fh. Returns true if there
 881  * are any, and false if not.
 882  */
 883 bool
 884 nfsd_file_is_cached(struct inode *inode)
 885 {
 886         bool                    ret = false;
 887         struct nfsd_file        *nf;
 888         unsigned int            hashval;
 889
 890         hashval = (unsigned int)hash_long(inode->i_ino, NFSD_FILE_HASH_BITS);
 891
 892         rcu_read_lock();
 893         hlist_for_each_entry_rcu(nf, &nfsd_file_hashtbl[hashval].nfb_head,
 894                                  nf_node) {
 895                 if (inode == nf->nf_inode) {
 896                         ret = true;
 897                         break;
 898                 }
 899         }
 900         rcu_read_unlock();
 901         trace_nfsd_file_is_cached(inode, hashval, (int)ret);
 902         return ret;
 903 }
 904
 905 static __be32
 906 nfsd_do_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
 907                      unsigned int may_flags, struct nfsd_file **pnf, bool open)
 908 {
 909         __be32  status;
 910         struct net *net = SVC_NET(rqstp);
 911         struct nfsd_file *nf, *new;
 912         struct inode *inode;
 913         unsigned int hashval;
 914         bool retry = true;
 915
 916         /* FIXME: skip this if fh_dentry is already set? */
 917         status = fh_verify(rqstp, fhp, S_IFREG,
 918                                 may_flags|NFSD_MAY_OWNER_OVERRIDE);
 919         if (status != nfs_ok)
 920                 return status;
 921
 922         inode = d_inode(fhp->fh_dentry);
 923         hashval = (unsigned int)hash_long(inode->i_ino, NFSD_FILE_HASH_BITS);
 924 retry:
 925         rcu_read_lock();
 926         nf = nfsd_file_find_locked(inode, may_flags, hashval, net);
 927         rcu_read_unlock();
 928         if (nf)
 929                 goto wait_for_construction;
 930
 931         new = nfsd_file_alloc(inode, may_flags, hashval, net);
 932         if (!new) {
 933                 trace_nfsd_file_acquire(rqstp, hashval, inode, may_flags,
 934                                         NULL, nfserr_jukebox);
 935                 return nfserr_jukebox;
 936         }
 937
 938         spin_lock(&nfsd_file_hashtbl[hashval].nfb_lock);
 939         nf = nfsd_file_find_locked(inode, may_flags, hashval, net);
 940         if (nf == NULL)
 941                 goto open_file;
 942         spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
 943         nfsd_file_slab_free(&new->nf_rcu);
 944
 945 wait_for_construction:
 946         wait_on_bit(&nf->nf_flags, NFSD_FILE_PENDING, TASK_UNINTERRUPTIBLE);
 947
 948         /* Did construction of this file fail? */
 949         if (!test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
 950                 if (!retry) {
 951                         status = nfserr_jukebox;
 952                         goto out;
 953                 }
 954                 retry = false;
 955                 nfsd_file_put_noref(nf);
 956                 goto retry;
 957         }
 958
 959         this_cpu_inc(nfsd_file_cache_hits);
 960
 961         if (!(may_flags & NFSD_MAY_NOT_BREAK_LEASE)) {
 962                 bool write = (may_flags & NFSD_MAY_WRITE);
 963
 964                 if (test_bit(NFSD_FILE_BREAK_READ, &nf->nf_flags) ||
 965                     (test_bit(NFSD_FILE_BREAK_WRITE, &nf->nf_flags) && write)) {
 966                         status = nfserrno(nfsd_open_break_lease(
 967                                         file_inode(nf->nf_file), may_flags));
 968                         if (status == nfs_ok) {
 969                                 clear_bit(NFSD_FILE_BREAK_READ, &nf->nf_flags);
 970                                 if (write)
 971                                         clear_bit(NFSD_FILE_BREAK_WRITE,
 972                                                   &nf->nf_flags);
 973                         }
 974                 }
 975         }
 976 out:
 977         if (status == nfs_ok) {
 978                 *pnf = nf;
 979         } else {
 980                 nfsd_file_put(nf);
 981                 nf = NULL;
 982         }
 983
 984         trace_nfsd_file_acquire(rqstp, hashval, inode, may_flags, nf, status);
 985         return status;
 986 open_file:
 987         nf = new;
 988         /* Take reference for the hashtable */
 989         refcount_inc(&nf->nf_ref);
 990         __set_bit(NFSD_FILE_HASHED, &nf->nf_flags);
 991         __set_bit(NFSD_FILE_PENDING, &nf->nf_flags);
 992         list_lru_add(&nfsd_file_lru, &nf->nf_lru);
 993         hlist_add_head_rcu(&nf->nf_node, &nfsd_file_hashtbl[hashval].nfb_head);
 994         ++nfsd_file_hashtbl[hashval].nfb_count;
 995         nfsd_file_hashtbl[hashval].nfb_maxcount = max(nfsd_file_hashtbl[hashval].nfb_maxcount,
 996                         nfsd_file_hashtbl[hashval].nfb_count);
 997         spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
 998         if (atomic_long_inc_return(&nfsd_filecache_count) >= NFSD_FILE_LRU_THRESHOLD)
 999                 nfsd_file_gc();
1000
1001         nf->nf_mark = nfsd_file_mark_find_or_create(nf);
1002         if (nf->nf_mark) {
1003                 if (open) {
1004                         status = nfsd_open_verified(rqstp, fhp, may_flags,
1005                                                     &nf->nf_file);
1006                         trace_nfsd_file_open(nf, status);
1007                 } else
1008                         status = nfs_ok;
1009         } else
1010                 status = nfserr_jukebox;
1011         /*
1012          * If construction failed, or we raced with a call to unlink()
1013          * then unhash.
1014          */
1015         if (status != nfs_ok || inode->i_nlink == 0) {
1016                 bool do_free;
1017                 spin_lock(&nfsd_file_hashtbl[hashval].nfb_lock);
1018                 do_free = nfsd_file_unhash(nf);
1019                 spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
1020                 if (do_free)
1021                         nfsd_file_put_noref(nf);
1022         }
1023         clear_bit_unlock(NFSD_FILE_PENDING, &nf->nf_flags);
1024         smp_mb__after_atomic();
1025         wake_up_bit(&nf->nf_flags, NFSD_FILE_PENDING);
1026         goto out;
1027 }
1028
1029 /**
1030  * nfsd_file_acquire - Get a struct nfsd_file with an open file
1031  * @rqstp: the RPC transaction being executed
1032  * @fhp: the NFS filehandle of the file to be opened
1033  * @may_flags: NFSD_MAY_ settings for the file
1034  * @pnf: OUT: new or found "struct nfsd_file" object
1035  *
1036  * Returns nfs_ok and sets @pnf on success; otherwise an nfsstat in
1037  * network byte order is returned.
1038  */
1039 __be32
1040 nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
1041                   unsigned int may_flags, struct nfsd_file **pnf)
1042 {
1043         return nfsd_do_file_acquire(rqstp, fhp, may_flags, pnf, true);
1044 }
1045
1046 /**
1047  * nfsd_file_create - Get a struct nfsd_file, do not open
1048  * @rqstp: the RPC transaction being executed
1049  * @fhp: the NFS filehandle of the file just created
1050  * @may_flags: NFSD_MAY_ settings for the file
1051  * @pnf: OUT: new or found "struct nfsd_file" object
1052  *
1053  * Returns nfs_ok and sets @pnf on success; otherwise an nfsstat in
1054  * network byte order is returned.
1055  */
1056 __be32
1057 nfsd_file_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1058                  unsigned int may_flags, struct nfsd_file **pnf)
1059 {
1060         return nfsd_do_file_acquire(rqstp, fhp, may_flags, pnf, false);
1061 }
1062
1063 /*
1064  * Note that fields may be added, removed or reordered in the future. Programs
1065  * scraping this file for info should test the labels to ensure they're
1066  * getting the correct field.
1067  */
1068 static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
1069 {
1070         unsigned int i, count = 0, longest = 0;
1071         unsigned long hits = 0;
1072
1073         /*
1074          * No need for spinlocks here since we're not terribly interested in
1075          * accuracy. We do take the nfsd_mutex simply to ensure that we
1076          * don't end up racing with server shutdown
1077          */
1078         mutex_lock(&nfsd_mutex);
1079         if (nfsd_file_hashtbl) {
1080                 for (i = 0; i < NFSD_FILE_HASH_SIZE; i++) {
1081                         count += nfsd_file_hashtbl[i].nfb_count;
1082                         longest = max(longest, nfsd_file_hashtbl[i].nfb_count);
1083                 }
1084         }
1085         mutex_unlock(&nfsd_mutex);
1086
1087         for_each_possible_cpu(i)
1088                 hits += per_cpu(nfsd_file_cache_hits, i);
1089
1090         seq_printf(m, "total entries: %u\n", count);
1091         seq_printf(m, "longest chain: %u\n", longest);
1092         seq_printf(m, "cache hits:    %lu\n", hits);
1093         return 0;
1094 }
1095
1096 int nfsd_file_cache_stats_open(struct inode *inode, struct file *file)
1097 {
1098         return single_open(file, nfsd_file_cache_stats_show, NULL);
1099 }