lustre/llite/llite_mmap.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  *  Copyright (c) 2001-2003 Cluster File Systems, Inc.
   5  *
   6  *   This file is part of Lustre, http://www.lustre.org.
   7  *
   8  *   Lustre is free software; you can redistribute it and/or
   9  *   modify it under the terms of version 2 of the GNU General Public
  10  *   License as published by the Free Software Foundation.
  11  *
  12  *   Lustre is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *   GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with Lustre; if not, write to the Free Software
  19  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #ifndef AUTOCONF_INCLUDED
  23 #include <linux/config.h>
  24 #endif
  25 #include <linux/kernel.h>
  26 #include <linux/mm.h>
  27 #include <linux/string.h>
  28 #include <linux/stat.h>
  29 #include <linux/errno.h>
  30 #include <linux/smp_lock.h>
  31 #include <linux/unistd.h>
  32 #include <linux/version.h>
  33 #include <asm/system.h>
  34 #include <asm/uaccess.h>
  35
  36 #include <linux/fs.h>
  37 #include <linux/stat.h>
  38 #include <asm/uaccess.h>
  39 #ifdef HAVE_SEGMENT_H
  40 # include <asm/segment.h>
  41 #endif
  42 #include <linux/mm.h>
  43 #include <linux/pagemap.h>
  44 #include <linux/smp_lock.h>
  45
  46 #define DEBUG_SUBSYSTEM S_LLITE
  47
  48 //#include <lustre_mdc.h>
  49 #include <lustre_lite.h>
  50 #include "llite_internal.h"
  51 #include <linux/lustre_compat25.h>
  52
  53 #define VMA_DEBUG(vma, fmt, arg...)                                     \
  54         CDEBUG(D_MMAP, "vma(%p) start(%ld) end(%ld) pgoff(%ld) inode(%p) "   \
  55                "ino(%lu) iname(%s): " fmt, vma, vma->vm_start, vma->vm_end,  \
  56                vma->vm_pgoff, vma->vm_file->f_dentry->d_inode,               \
  57                vma->vm_file->f_dentry->d_inode->i_ino,                       \
  58                vma->vm_file->f_dentry->d_iname, ## arg);                     \
  59
  60
  61 struct ll_lock_tree_node {
  62         rb_node_t               lt_node;
  63         struct list_head        lt_locked_item;
  64         __u64                   lt_oid;
  65         ldlm_policy_data_t      lt_policy;
  66         struct lustre_handle    lt_lockh;
  67         ldlm_mode_t             lt_mode;
  68         struct inode           *lt_inode;
  69 };
  70
  71 int lt_get_mmap_locks(struct ll_lock_tree *tree,
  72                       unsigned long addr, size_t count);
  73
  74 struct page *ll_nopage(struct vm_area_struct *vma, unsigned long address,
  75                        int *type);
  76
  77 struct ll_lock_tree_node * ll_node_from_inode(struct inode *inode, __u64 start,
  78                                               __u64 end, ldlm_mode_t mode)
  79 {
  80         struct ll_lock_tree_node *node;
  81
  82         OBD_ALLOC(node, sizeof(*node));
  83         if (node == NULL)
  84                 RETURN(ERR_PTR(-ENOMEM));
  85
  86         node->lt_inode = inode;
  87         node->lt_oid = ll_i2info(inode)->lli_smd->lsm_object_id;
  88         node->lt_policy.l_extent.start = start;
  89         node->lt_policy.l_extent.end = end;
  90         memset(&node->lt_lockh, 0, sizeof(node->lt_lockh));
  91         INIT_LIST_HEAD(&node->lt_locked_item);
  92         node->lt_mode = mode;
  93
  94         return node;
  95 }
  96
  97 int lt_compare(struct ll_lock_tree_node *one, struct ll_lock_tree_node *two)
  98 {
  99         /* To avoid multiple fs deadlock */
 100         if (one->lt_inode->i_sb->s_dev < two->lt_inode->i_sb->s_dev)
 101                 return -1;
 102         if (one->lt_inode->i_sb->s_dev > two->lt_inode->i_sb->s_dev)
 103                 return 1;
 104
 105         if (one->lt_oid < two->lt_oid)
 106                 return -1;
 107         if (one->lt_oid > two->lt_oid)
 108                 return 1;
 109
 110         if (one->lt_policy.l_extent.end < two->lt_policy.l_extent.start)
 111                 return -1;
 112         if (one->lt_policy.l_extent.start > two->lt_policy.l_extent.end)
 113                 return 1;
 114
 115         return 0; /* they are the same object and overlap */
 116 }
 117
 118 static void lt_merge(struct ll_lock_tree_node *dst,
 119                      struct ll_lock_tree_node *src)
 120 {
 121         dst->lt_policy.l_extent.start = min(dst->lt_policy.l_extent.start,
 122                                             src->lt_policy.l_extent.start);
 123         dst->lt_policy.l_extent.end = max(dst->lt_policy.l_extent.end,
 124                                           src->lt_policy.l_extent.end);
 125
 126         /* XXX could be a real call to the dlm to find superset modes */
 127         if (src->lt_mode == LCK_PW && dst->lt_mode != LCK_PW)
 128                 dst->lt_mode = LCK_PW;
 129 }
 130
 131 static void lt_insert(struct ll_lock_tree *tree,
 132                       struct ll_lock_tree_node *node)
 133 {
 134         struct ll_lock_tree_node *walk;
 135         rb_node_t **p, *parent;
 136         ENTRY;
 137
 138 restart:
 139         p = &tree->lt_root.rb_node;
 140         parent = NULL;
 141         while (*p) {
 142                 parent = *p;
 143                 walk = rb_entry(parent, struct ll_lock_tree_node, lt_node);
 144                 switch (lt_compare(node, walk)) {
 145                 case -1:
 146                         p = &(*p)->rb_left;
 147                         break;
 148                 case 1:
 149                         p = &(*p)->rb_right;
 150                         break;
 151                 case 0:
 152                         lt_merge(node, walk);
 153                         rb_erase(&walk->lt_node, &tree->lt_root);
 154                         OBD_FREE(walk, sizeof(*walk));
 155                         goto restart;
 156                         break;
 157                 default:
 158                         LBUG();
 159                         break;
 160                 }
 161         }
 162         rb_link_node(&node->lt_node, parent, p);
 163         rb_insert_color(&node->lt_node, &tree->lt_root);
 164         EXIT;
 165 }
 166
 167 static struct ll_lock_tree_node *lt_least_node(struct ll_lock_tree *tree)
 168 {
 169         rb_node_t *rbnode;
 170         struct ll_lock_tree_node *node = NULL;
 171
 172         for ( rbnode = tree->lt_root.rb_node; rbnode != NULL;
 173               rbnode = rbnode->rb_left) {
 174                 if (rbnode->rb_left == NULL) {
 175                         node = rb_entry(rbnode, struct ll_lock_tree_node,
 176                                         lt_node);
 177                         break;
 178                 }
 179         }
 180         RETURN(node);
 181 }
 182
 183 int ll_tree_unlock(struct ll_lock_tree *tree)
 184 {
 185         struct ll_lock_tree_node *node;
 186         struct list_head *pos, *n;
 187         struct inode *inode;
 188         int rc = 0;
 189         ENTRY;
 190
 191         list_for_each_safe(pos, n, &tree->lt_locked_list) {
 192                 node = list_entry(pos, struct ll_lock_tree_node,
 193                                   lt_locked_item);
 194
 195                 inode = node->lt_inode;
 196                 rc = ll_extent_unlock(tree->lt_fd, inode,
 197                                       ll_i2info(inode)->lli_smd, node->lt_mode,
 198                                       &node->lt_lockh);
 199                 if (rc != 0) {
 200                         /* XXX better message */
 201                         CERROR("couldn't unlock %d\n", rc);
 202                 }
 203                 list_del(&node->lt_locked_item);
 204                 OBD_FREE(node, sizeof(*node));
 205         }
 206
 207         while ((node = lt_least_node(tree))) {
 208                 rb_erase(&node->lt_node, &tree->lt_root);
 209                 OBD_FREE(node, sizeof(*node));
 210         }
 211
 212         RETURN(rc);
 213 }
 214
 215 int ll_tree_lock(struct ll_lock_tree *tree,
 216                  struct ll_lock_tree_node *first_node,
 217                  const char *buf, size_t count, int ast_flags)
 218 {
 219         struct ll_lock_tree_node *node;
 220         int rc = 0;
 221         ENTRY;
 222
 223         tree->lt_root.rb_node = NULL;
 224         INIT_LIST_HEAD(&tree->lt_locked_list);
 225         if (first_node != NULL)
 226                 lt_insert(tree, first_node);
 227
 228         /* To avoid such subtle deadlock case: client1 try to read file1 to
 229          * mmapped file2, on the same time, client2 try to read file2 to
 230          * mmapped file1.*/
 231         rc = lt_get_mmap_locks(tree, (unsigned long)buf, count);
 232         if (rc)
 233                 GOTO(out, rc);
 234
 235         while ((node = lt_least_node(tree))) {
 236                 struct inode *inode = node->lt_inode;
 237                 rc = ll_extent_lock(tree->lt_fd, inode,
 238                                     ll_i2info(inode)->lli_smd, node->lt_mode,
 239                                     &node->lt_policy, &node->lt_lockh,
 240                                     ast_flags);
 241                 if (rc != 0)
 242                         GOTO(out, rc);
 243
 244                 rb_erase(&node->lt_node, &tree->lt_root);
 245                 list_add_tail(&node->lt_locked_item, &tree->lt_locked_list);
 246         }
 247         RETURN(rc);
 248 out:
 249         ll_tree_unlock(tree);
 250         RETURN(rc);
 251 }
 252
 253 static ldlm_mode_t mode_from_vma(struct vm_area_struct *vma)
 254 {
 255         /* we only want to hold PW locks if the mmap() can generate
 256          * writes back to the file and that only happens in shared
 257          * writable vmas */
 258         if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE))
 259                 return LCK_PW;
 260         return LCK_PR;
 261 }
 262
 263 static void policy_from_vma(ldlm_policy_data_t *policy,
 264                             struct vm_area_struct *vma, unsigned long addr,
 265                             size_t count)
 266 {
 267         policy->l_extent.start = ((addr - vma->vm_start) & CFS_PAGE_MASK) +
 268                                  (vma->vm_pgoff << CFS_PAGE_SHIFT);
 269         policy->l_extent.end = (policy->l_extent.start + count - 1) |
 270                                ~CFS_PAGE_MASK;
 271 }
 272
 273 static struct vm_area_struct * our_vma(unsigned long addr, size_t count)
 274 {
 275         struct mm_struct *mm = current->mm;
 276         struct vm_area_struct *vma, *ret = NULL;
 277         ENTRY;
 278
 279         /* No MM (e.g. NFS)? No vmas too. */
 280         if (!mm)
 281                 RETURN(NULL);
 282
 283         spin_lock(&mm->page_table_lock);
 284         for(vma = find_vma(mm, addr);
 285             vma != NULL && vma->vm_start < (addr + count); vma = vma->vm_next) {
 286                 if (vma->vm_ops && vma->vm_ops->nopage == ll_nopage &&
 287                     vma->vm_flags & VM_SHARED) {
 288                         ret = vma;
 289                         break;
 290                 }
 291         }
 292         spin_unlock(&mm->page_table_lock);
 293         RETURN(ret);
 294 }
 295
 296 int lt_get_mmap_locks(struct ll_lock_tree *tree,
 297                       unsigned long addr, size_t count)
 298 {
 299         struct vm_area_struct *vma;
 300         struct ll_lock_tree_node *node;
 301         ldlm_policy_data_t policy;
 302         struct inode *inode;
 303         ENTRY;
 304
 305         if (count == 0)
 306                 RETURN(0);
 307
 308         /* we need to look up vmas on page aligned addresses */
 309         count += addr & (~CFS_PAGE_MASK);
 310         addr &= CFS_PAGE_MASK;
 311
 312         while ((vma = our_vma(addr, count)) != NULL) {
 313                 LASSERT(vma->vm_file);
 314
 315                 inode = vma->vm_file->f_dentry->d_inode;
 316                 policy_from_vma(&policy, vma, addr, count);
 317                 node = ll_node_from_inode(inode, policy.l_extent.start,
 318                                           policy.l_extent.end,
 319                                           mode_from_vma(vma));
 320                 if (IS_ERR(node)) {
 321                         CERROR("not enough mem for lock_tree_node!\n");
 322                         RETURN(-ENOMEM);
 323                 }
 324                 lt_insert(tree, node);
 325
 326                 if (vma->vm_end - addr >= count)
 327                         break;
 328                 count -= vma->vm_end - addr;
 329                 addr = vma->vm_end;
 330         }
 331         RETURN(0);
 332 }
 333
 334 /* FIXME: there is a pagefault race goes as follow (only 2.4):
 335  * 1. A user process on node A accesses a portion of a mapped file,
 336  *    resulting in a page fault.  The pagefault handler invokes the
 337  *    ll_nopage function, which reads the page into memory.
 338  * 2. A user process on node B writes to the same portion of the file
 339  *    (either via mmap or write()), that cause node A to cancel the
 340  *    lock and truncate the page.
 341  * 3. Node A then executes the rest of do_no_page(), entering the
 342  *    now-invalid page into the PTEs.
 343  *
 344  * Make the whole do_no_page as a hook to cover both the page cache
 345  * and page mapping installing with dlm lock would eliminate this race.
 346  *
 347  * In 2.6, the truncate_count of address_space can cover this race.
 348  */
 349 struct page *ll_nopage(struct vm_area_struct *vma, unsigned long address,
 350                        int *type)
 351 {
 352         struct file *filp = vma->vm_file;
 353         struct ll_file_data *fd = LUSTRE_FPRIVATE(filp);
 354         struct inode *inode = filp->f_dentry->d_inode;
 355         struct lustre_handle lockh = { 0 };
 356         ldlm_policy_data_t policy;
 357         ldlm_mode_t mode;
 358         struct page *page = NULL;
 359         struct ll_inode_info *lli = ll_i2info(inode);
 360         struct lov_stripe_md *lsm;
 361         struct ost_lvb lvb;
 362         __u64 kms, old_mtime;
 363         unsigned long pgoff, size, rand_read, seq_read;
 364         int rc = 0;
 365         ENTRY;
 366
 367         if (lli->lli_smd == NULL) {
 368                 CERROR("No lsm on fault?\n");
 369                 RETURN(NULL);
 370         }
 371
 372         /* start and end the lock on the first and last bytes in the page */
 373         policy_from_vma(&policy, vma, address, CFS_PAGE_SIZE);
 374
 375         CDEBUG(D_MMAP, "nopage vma %p inode %lu, locking ["LPU64", "LPU64"]\n",
 376                vma, inode->i_ino, policy.l_extent.start, policy.l_extent.end);
 377
 378         mode = mode_from_vma(vma);
 379         old_mtime = LTIME_S(inode->i_mtime);
 380
 381         lsm = lli->lli_smd;
 382         rc = ll_extent_lock(fd, inode, lsm, mode, &policy,
 383                             &lockh, LDLM_FL_CBPENDING | LDLM_FL_NO_LRU);
 384         if (rc != 0)
 385                 RETURN(NULL);
 386
 387         if (vma->vm_flags & VM_EXEC && LTIME_S(inode->i_mtime) != old_mtime)
 388                 CWARN("binary changed. inode %lu\n", inode->i_ino);
 389
 390         lov_stripe_lock(lsm);
 391         inode_init_lvb(inode, &lvb);
 392         obd_merge_lvb(ll_i2dtexp(inode), lsm, &lvb, 1);
 393         kms = lvb.lvb_size;
 394
 395         pgoff = ((address - vma->vm_start) >> CFS_PAGE_SHIFT) + vma->vm_pgoff;
 396         size = (kms + CFS_PAGE_SIZE - 1) >> CFS_PAGE_SHIFT;
 397
 398         if (pgoff >= size) {
 399                 lov_stripe_unlock(lsm);
 400                 ll_glimpse_size(inode, LDLM_FL_BLOCK_GRANTED);
 401         } else {
 402                 /* XXX change inode size without ll_inode_size_lock() held!
 403                  *     there is a race condition with truncate path. (see
 404                  *     ll_extent_lock) */
 405                 /* XXX i_size_write() is not used because it is not safe to
 406                  *     take the ll_inode_size_lock() due to a potential lock
 407                  *     inversion (bug 6077).  And since it's not safe to use
 408                  *     i_size_write() without a covering mutex we do the
 409                  *     assignment directly.  It is not critical that the
 410                  *     size be correct. */
 411                 /* region is within kms and, hence, within real file size (A).
 412                  * We need to increase i_size to cover the read region so that
 413                  * generic_file_read() will do its job, but that doesn't mean
 414                  * the kms size is _correct_, it is only the _minimum_ size.
 415                  * If someone does a stat they will get the correct size which
 416                  * will always be >= the kms value here.  b=11081 */
 417                 if (i_size_read(inode) < kms) {
 418                         inode->i_size = kms;
 419                         CDEBUG(D_INODE, "ino=%lu, updating i_size %llu\n",
 420                                inode->i_ino, i_size_read(inode));
 421                 }
 422                 lov_stripe_unlock(lsm);
 423         }
 424
 425         /* If mapping is writeable, adjust kms to cover this page,
 426          * but do not extend kms beyond actual file size.
 427          * policy.l_extent.end is set to the end of the page by policy_from_vma
 428          * bug 10919 */
 429         lov_stripe_lock(lsm);
 430         if (mode == LCK_PW)
 431                 obd_adjust_kms(ll_i2dtexp(inode), lsm,
 432                                min_t(loff_t, policy.l_extent.end + 1,
 433                                i_size_read(inode)), 0);
 434         lov_stripe_unlock(lsm);
 435
 436         /* disable VM_SEQ_READ and use VM_RAND_READ to make sure that
 437          * the kernel will not read other pages not covered by ldlm in
 438          * filemap_nopage. we do our readahead in ll_readpage.
 439          */
 440         rand_read = vma->vm_flags & VM_RAND_READ;
 441         seq_read = vma->vm_flags & VM_SEQ_READ;
 442         vma->vm_flags &= ~ VM_SEQ_READ;
 443         vma->vm_flags |= VM_RAND_READ;
 444
 445         page = filemap_nopage(vma, address, type);
 446         LL_CDEBUG_PAGE(D_PAGE, page, "got addr %lu type %lx\n", address,
 447                        (long)type);
 448         vma->vm_flags &= ~VM_RAND_READ;
 449         vma->vm_flags |= (rand_read | seq_read);
 450
 451         ll_extent_unlock(fd, inode, ll_i2info(inode)->lli_smd, mode, &lockh);
 452         RETURN(page);
 453 }
 454
 455 /* To avoid cancel the locks covering mmapped region for lock cache pressure,
 456  * we track the mapped vma count by lli_mmap_cnt.
 457  * ll_vm_open():  when first vma is linked, split locks from lru.
 458  * ll_vm_close(): when last vma is unlinked, join all this file's locks to lru.
 459  *
 460  * XXX we don't check the if the region of vma/lock for performance.
 461  */
 462 static void ll_vm_open(struct vm_area_struct * vma)
 463 {
 464         struct inode *inode = vma->vm_file->f_dentry->d_inode;
 465         struct ll_inode_info *lli = ll_i2info(inode);
 466         ENTRY;
 467
 468         LASSERT(vma->vm_file);
 469
 470         spin_lock(&lli->lli_lock);
 471         LASSERT(atomic_read(&lli->lli_mmap_cnt) >= 0);
 472
 473         atomic_inc(&lli->lli_mmap_cnt);
 474         if (atomic_read(&lli->lli_mmap_cnt) == 1) {
 475                 struct lov_stripe_md *lsm = lli->lli_smd;
 476                 struct ll_sb_info *sbi = ll_i2sbi(inode);
 477                 int count;
 478
 479                 spin_unlock(&lli->lli_lock);
 480
 481                 if (!lsm)
 482                         return;
 483                 count = obd_join_lru(sbi->ll_dt_exp, lsm, 0);
 484                 VMA_DEBUG(vma, "split %d unused locks from lru\n", count);
 485         } else {
 486                 spin_unlock(&lli->lli_lock);
 487         }
 488
 489 }
 490
 491 static void ll_vm_close(struct vm_area_struct *vma)
 492 {
 493         struct inode *inode = vma->vm_file->f_dentry->d_inode;
 494         struct ll_inode_info *lli = ll_i2info(inode);
 495         ENTRY;
 496
 497         LASSERT(vma->vm_file);
 498
 499         spin_lock(&lli->lli_lock);
 500         LASSERT(atomic_read(&lli->lli_mmap_cnt) > 0);
 501
 502         atomic_dec(&lli->lli_mmap_cnt);
 503         if (atomic_read(&lli->lli_mmap_cnt) == 0) {
 504                 struct lov_stripe_md *lsm = lli->lli_smd;
 505                 struct ll_sb_info *sbi = ll_i2sbi(inode);
 506                 int count;
 507
 508                 spin_unlock(&lli->lli_lock);
 509
 510                 if (!lsm)
 511                         return;
 512                 count = obd_join_lru(sbi->ll_dt_exp, lsm, 1);
 513                 VMA_DEBUG(vma, "join %d unused locks to lru\n", count);
 514         } else {
 515                 spin_unlock(&lli->lli_lock);
 516         }
 517 }
 518
 519 #ifndef HAVE_FILEMAP_POPULATE
 520 static int (*filemap_populate)(struct vm_area_struct * area, unsigned long address, unsigned long len, pgprot_t prot, unsigned long pgoff, int nonblock);
 521 #endif
 522 static int ll_populate(struct vm_area_struct *area, unsigned long address,
 523                        unsigned long len, pgprot_t prot, unsigned long pgoff,
 524                        int nonblock)
 525 {
 526         int rc = 0;
 527         ENTRY;
 528
 529         /* always set nonblock as true to avoid page read ahead */
 530         rc = filemap_populate(area, address, len, prot, pgoff, 1);
 531         RETURN(rc);
 532 }
 533
 534 /* return the user space pointer that maps to a file offset via a vma */
 535 static inline unsigned long file_to_user(struct vm_area_struct *vma, __u64 byte)
 536 {
 537         return vma->vm_start + (byte - ((__u64)vma->vm_pgoff << CFS_PAGE_SHIFT));
 538
 539 }
 540
 541 /* XXX put nice comment here.  talk about __free_pte -> dirty pages and
 542  * nopage's reference passing to the pte */
 543 int ll_teardown_mmaps(struct address_space *mapping, __u64 first, __u64 last)
 544 {
 545         int rc = -ENOENT;
 546         ENTRY;
 547
 548         LASSERTF(last > first, "last "LPU64" first "LPU64"\n", last, first);
 549         if (mapping_mapped(mapping)) {
 550                 rc = 0;
 551                 unmap_mapping_range(mapping, first + CFS_PAGE_SIZE - 1,
 552                                     last - first + 1, 0);
 553         }
 554
 555         RETURN(rc);
 556 }
 557
 558 static struct vm_operations_struct ll_file_vm_ops = {
 559         .nopage         = ll_nopage,
 560         .open           = ll_vm_open,
 561         .close          = ll_vm_close,
 562         .populate       = ll_populate,
 563 };
 564
 565 int ll_file_mmap(struct file * file, struct vm_area_struct * vma)
 566 {
 567         int rc;
 568         ENTRY;
 569
 570         ll_stats_ops_tally(ll_i2sbi(file->f_dentry->d_inode), LPROC_LL_MAP, 1);
 571         rc = generic_file_mmap(file, vma);
 572         if (rc == 0) {
 573 #if !defined(HAVE_FILEMAP_POPULATE)
 574                 if (!filemap_populate)
 575                         filemap_populate = vma->vm_ops->populate;
 576 #endif
 577                 vma->vm_ops = &ll_file_vm_ops;
 578                 vma->vm_ops->open(vma);
 579                 /* update the inode's size and mtime */
 580                 rc = ll_glimpse_size(file->f_dentry->d_inode, 0);
 581         }
 582
 583         RETURN(rc);
 584 }