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