lustre/llite/rw26.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2014, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * lustre/lustre/llite/rw26.c
  37  *
  38  * Lustre Lite I/O page cache routines for the 2.5/2.6 kernel version
  39  */
  40
  41 #include <linux/kernel.h>
  42 #include <linux/mm.h>
  43 #include <linux/string.h>
  44 #include <linux/stat.h>
  45 #include <linux/errno.h>
  46 #include <linux/unistd.h>
  47 #include <asm/uaccess.h>
  48
  49 #ifdef HAVE_MIGRATE_H
  50 #include <linux/migrate.h>
  51 #elif defined(HAVE_MIGRATE_MODE_H)
  52 #include <linux/migrate_mode.h>
  53 #endif
  54 #include <linux/fs.h>
  55 #include <linux/buffer_head.h>
  56 #include <linux/mpage.h>
  57 #include <linux/writeback.h>
  58 #include <linux/stat.h>
  59 #include <asm/uaccess.h>
  60 #include <linux/mm.h>
  61 #include <linux/pagemap.h>
  62
  63 #define DEBUG_SUBSYSTEM S_LLITE
  64
  65 #include "llite_internal.h"
  66 #include <lustre_compat.h>
  67
  68 /**
  69  * Implements Linux VM address_space::invalidatepage() method. This method is
  70  * called when the page is truncate from a file, either as a result of
  71  * explicit truncate, or when inode is removed from memory (as a result of
  72  * final iput(), umount, or memory pressure induced icache shrinking).
  73  *
  74  * [0, offset] bytes of the page remain valid (this is for a case of not-page
  75  * aligned truncate). Lustre leaves partially truncated page in the cache,
  76  * relying on struct inode::i_size to limit further accesses.
  77  */
  78 static void ll_invalidatepage(struct page *vmpage,
  79 #ifdef HAVE_INVALIDATE_RANGE
  80                                 unsigned int offset, unsigned int length
  81 #else
  82                                 unsigned long offset
  83 #endif
  84                              )
  85 {
  86         struct inode     *inode;
  87         struct lu_env    *env;
  88         struct cl_page   *page;
  89         struct cl_object *obj;
  90
  91         __u16 refcheck;
  92
  93         LASSERT(PageLocked(vmpage));
  94         LASSERT(!PageWriteback(vmpage));
  95
  96         /*
  97          * It is safe to not check anything in invalidatepage/releasepage
  98          * below because they are run with page locked and all our io is
  99          * happening with locked page too
 100          */
 101 #ifdef HAVE_INVALIDATE_RANGE
 102         if (offset == 0 && length == PAGE_SIZE) {
 103 #else
 104         if (offset == 0) {
 105 #endif
 106                 env = cl_env_get(&refcheck);
 107                 if (!IS_ERR(env)) {
 108                         inode = vmpage->mapping->host;
 109                         obj = ll_i2info(inode)->lli_clob;
 110                         if (obj != NULL) {
 111                                 page = cl_vmpage_page(vmpage, obj);
 112                                 if (page != NULL) {
 113                                         cl_page_delete(env, page);
 114                                         cl_page_put(env, page);
 115                                 }
 116                         } else
 117                                 LASSERT(vmpage->private == 0);
 118                         cl_env_put(env, &refcheck);
 119                 }
 120         }
 121 }
 122
 123 #ifdef HAVE_RELEASEPAGE_WITH_INT
 124 #define RELEASEPAGE_ARG_TYPE int
 125 #else
 126 #define RELEASEPAGE_ARG_TYPE gfp_t
 127 #endif
 128 static int ll_releasepage(struct page *vmpage, RELEASEPAGE_ARG_TYPE gfp_mask)
 129 {
 130         struct lu_env           *env;
 131         struct cl_object        *obj;
 132         struct cl_page          *page;
 133         struct address_space    *mapping;
 134         int result = 0;
 135
 136         LASSERT(PageLocked(vmpage));
 137         if (PageWriteback(vmpage) || PageDirty(vmpage))
 138                 return 0;
 139
 140         mapping = vmpage->mapping;
 141         if (mapping == NULL)
 142                 return 1;
 143
 144         obj = ll_i2info(mapping->host)->lli_clob;
 145         if (obj == NULL)
 146                 return 1;
 147
 148         /* 1 for caller, 1 for cl_page and 1 for page cache */
 149         if (page_count(vmpage) > 3)
 150                 return 0;
 151
 152         page = cl_vmpage_page(vmpage, obj);
 153         if (page == NULL)
 154                 return 1;
 155
 156         env = cl_env_percpu_get();
 157         LASSERT(!IS_ERR(env));
 158
 159         if (!cl_page_in_use(page)) {
 160                 result = 1;
 161                 cl_page_delete(env, page);
 162         }
 163
 164         /* To use percpu env array, the call path can not be rescheduled;
 165          * otherwise percpu array will be messed if ll_releaspage() called
 166          * again on the same CPU.
 167          *
 168          * If this page holds the last refc of cl_object, the following
 169          * call path may cause reschedule:
 170          *   cl_page_put -> cl_page_free -> cl_object_put ->
 171          *     lu_object_put -> lu_object_free -> lov_delete_raid0.
 172          *
 173          * However, the kernel can't get rid of this inode until all pages have
 174          * been cleaned up. Now that we hold page lock here, it's pretty safe
 175          * that we won't get into object delete path.
 176          */
 177         LASSERT(cl_object_refc(obj) > 1);
 178         cl_page_put(env, page);
 179
 180         cl_env_percpu_put(env);
 181         return result;
 182 }
 183
 184 #define MAX_DIRECTIO_SIZE 2*1024*1024*1024UL
 185
 186 ssize_t ll_direct_rw_pages(const struct lu_env *env, struct cl_io *io,
 187                            int rw, struct inode *inode,
 188                            struct ll_dio_pages *pv)
 189 {
 190         struct cl_page    *clp;
 191         struct cl_2queue  *queue;
 192         struct cl_object  *obj = io->ci_obj;
 193         int i;
 194         ssize_t rc = 0;
 195         loff_t file_offset  = pv->ldp_start_offset;
 196         size_t size         = pv->ldp_size;
 197         int page_count      = pv->ldp_nr;
 198         struct page **pages = pv->ldp_pages;
 199         size_t page_size    = cl_page_size(obj);
 200         bool do_io;
 201         int  io_pages       = 0;
 202         ENTRY;
 203
 204         queue = &io->ci_queue;
 205         cl_2queue_init(queue);
 206         for (i = 0; i < page_count; i++) {
 207                 if (pv->ldp_offsets)
 208                     file_offset = pv->ldp_offsets[i];
 209
 210                 LASSERT(!(file_offset & (page_size - 1)));
 211                 clp = cl_page_find(env, obj, cl_index(obj, file_offset),
 212                                    pv->ldp_pages[i], CPT_TRANSIENT);
 213                 if (IS_ERR(clp)) {
 214                         rc = PTR_ERR(clp);
 215                         break;
 216                 }
 217
 218                 rc = cl_page_own(env, io, clp);
 219                 if (rc) {
 220                         LASSERT(clp->cp_state == CPS_FREEING);
 221                         cl_page_put(env, clp);
 222                         break;
 223                 }
 224
 225                 do_io = true;
 226
 227                 /* check the page type: if the page is a host page, then do
 228                  * write directly */
 229                 if (clp->cp_type == CPT_CACHEABLE) {
 230                         struct page *vmpage = cl_page_vmpage(clp);
 231                         struct page *src_page;
 232                         struct page *dst_page;
 233                         void       *src;
 234                         void       *dst;
 235
 236                         src_page = (rw == WRITE) ? pages[i] : vmpage;
 237                         dst_page = (rw == WRITE) ? vmpage : pages[i];
 238
 239                         src = ll_kmap_atomic(src_page, KM_USER0);
 240                         dst = ll_kmap_atomic(dst_page, KM_USER1);
 241                         memcpy(dst, src, min(page_size, size));
 242                         ll_kunmap_atomic(dst, KM_USER1);
 243                         ll_kunmap_atomic(src, KM_USER0);
 244
 245                         /* make sure page will be added to the transfer by
 246                          * cl_io_submit()->...->vvp_page_prep_write(). */
 247                         if (rw == WRITE)
 248                                 set_page_dirty(vmpage);
 249
 250                         if (rw == READ) {
 251                                 /* do not issue the page for read, since it
 252                                  * may reread a ra page which has NOT uptodate
 253                                  * bit set. */
 254                                 cl_page_disown(env, io, clp);
 255                                 do_io = false;
 256                         }
 257                 }
 258
 259                 if (likely(do_io)) {
 260                         cl_2queue_add(queue, clp);
 261
 262                         /*
 263                          * Set page clip to tell transfer formation engine
 264                          * that page has to be sent even if it is beyond KMS.
 265                          */
 266                         cl_page_clip(env, clp, 0, min(size, page_size));
 267
 268                         ++io_pages;
 269                 }
 270
 271                 /* drop the reference count for cl_page_find */
 272                 cl_page_put(env, clp);
 273                 size -= page_size;
 274                 file_offset += page_size;
 275         }
 276
 277         if (rc == 0 && io_pages) {
 278                 rc = cl_io_submit_sync(env, io,
 279                                        rw == READ ? CRT_READ : CRT_WRITE,
 280                                        queue, 0);
 281         }
 282         if (rc == 0)
 283                 rc = pv->ldp_size;
 284
 285         cl_2queue_discard(env, io, queue);
 286         cl_2queue_disown(env, io, queue);
 287         cl_2queue_fini(env, queue);
 288         RETURN(rc);
 289 }
 290 EXPORT_SYMBOL(ll_direct_rw_pages);
 291
 292 static ssize_t
 293 ll_direct_IO_seg(const struct lu_env *env, struct cl_io *io, int rw,
 294                  struct inode *inode, size_t size, loff_t file_offset,
 295                  struct page **pages, int page_count)
 296 {
 297         struct ll_dio_pages pvec = { .ldp_pages         = pages,
 298                                      .ldp_nr            = page_count,
 299                                      .ldp_size          = size,
 300                                      .ldp_offsets       = NULL,
 301                                      .ldp_start_offset  = file_offset
 302                                    };
 303
 304         return ll_direct_rw_pages(env, io, rw, inode, &pvec);
 305 }
 306
 307 /*  ll_free_user_pages - tear down page struct array
 308  *  @pages: array of page struct pointers underlying target buffer */
 309 static void ll_free_user_pages(struct page **pages, int npages, int do_dirty)
 310 {
 311         int i;
 312
 313         for (i = 0; i < npages; i++) {
 314                 if (pages[i] == NULL)
 315                         break;
 316                 if (do_dirty)
 317                         set_page_dirty_lock(pages[i]);
 318                 page_cache_release(pages[i]);
 319         }
 320
 321 #if defined(HAVE_DIRECTIO_ITER) || defined(HAVE_IOV_ITER_RW)
 322         kvfree(pages);
 323 #else
 324         OBD_FREE_LARGE(pages, npages * sizeof(*pages));
 325 #endif
 326 }
 327
 328 #ifdef KMALLOC_MAX_SIZE
 329 #define MAX_MALLOC KMALLOC_MAX_SIZE
 330 #else
 331 #define MAX_MALLOC (128 * 1024)
 332 #endif
 333
 334 /* This is the maximum size of a single O_DIRECT request, based on the
 335  * kmalloc limit.  We need to fit all of the brw_page structs, each one
 336  * representing PAGE_SIZE worth of user data, into a single buffer, and
 337  * then truncate this to be a full-sized RPC.  For 4kB PAGE_SIZE this is
 338  * up to 22MB for 128kB kmalloc and up to 682MB for 4MB kmalloc. */
 339 #define MAX_DIO_SIZE ((MAX_MALLOC / sizeof(struct brw_page) * PAGE_SIZE) & \
 340                       ~(DT_MAX_BRW_SIZE - 1))
 341
 342 #ifndef HAVE_IOV_ITER_RW
 343 # define iov_iter_rw(iter)      rw
 344 #endif
 345
 346 #if defined(HAVE_DIRECTIO_ITER) || defined(HAVE_IOV_ITER_RW)
 347 static ssize_t
 348 ll_direct_IO(
 349 # ifndef HAVE_IOV_ITER_RW
 350              int rw,
 351 # endif
 352              struct kiocb *iocb, struct iov_iter *iter,
 353              loff_t file_offset)
 354 {
 355         struct ll_cl_context *lcc;
 356         const struct lu_env *env;
 357         struct cl_io *io;
 358         struct file *file = iocb->ki_filp;
 359         struct inode *inode = file->f_mapping->host;
 360         ssize_t count = iov_iter_count(iter);
 361         ssize_t tot_bytes = 0, result = 0;
 362         size_t size = MAX_DIO_SIZE;
 363
 364         /* FIXME: io smaller than PAGE_SIZE is broken on ia64 ??? */
 365         if ((file_offset & ~PAGE_MASK) || (count & ~PAGE_MASK))
 366                 return -EINVAL;
 367
 368         CDEBUG(D_VFSTRACE, "VFS Op:inode="DFID"(%p), size=%zd (max %lu), "
 369                "offset=%lld=%llx, pages %zd (max %lu)\n",
 370                PFID(ll_inode2fid(inode)), inode, count, MAX_DIO_SIZE,
 371                file_offset, file_offset, count >> PAGE_SHIFT,
 372                MAX_DIO_SIZE >> PAGE_SHIFT);
 373
 374         /* Check that all user buffers are aligned as well */
 375         if (iov_iter_alignment(iter) & ~PAGE_MASK)
 376                 return -EINVAL;
 377
 378         lcc = ll_cl_find(file);
 379         if (lcc == NULL)
 380                 RETURN(-EIO);
 381
 382         env = lcc->lcc_env;
 383         LASSERT(!IS_ERR(env));
 384         io = lcc->lcc_io;
 385         LASSERT(io != NULL);
 386
 387         /* 0. Need locking between buffered and direct access. and race with
 388          *    size changing by concurrent truncates and writes.
 389          * 1. Need inode mutex to operate transient pages.
 390          */
 391         if (iov_iter_rw(iter) == READ)
 392                 inode_lock(inode);
 393
 394         while (iov_iter_count(iter)) {
 395                 struct page **pages;
 396                 size_t offs;
 397
 398                 count = min_t(size_t, iov_iter_count(iter), size);
 399                 if (iov_iter_rw(iter) == READ) {
 400                         if (file_offset >= i_size_read(inode))
 401                                 break;
 402
 403                         if (file_offset + count > i_size_read(inode))
 404                                 count = i_size_read(inode) - file_offset;
 405                 }
 406
 407                 result = iov_iter_get_pages_alloc(iter, &pages, count, &offs);
 408                 if (likely(result > 0)) {
 409                         int n = DIV_ROUND_UP(result + offs, PAGE_SIZE);
 410
 411                         result = ll_direct_IO_seg(env, io, iov_iter_rw(iter),
 412                                                   inode, result, file_offset,
 413                                                   pages, n);
 414                         ll_free_user_pages(pages, n,
 415                                            iov_iter_rw(iter) == READ);
 416
 417                 }
 418                 if (unlikely(result <= 0)) {
 419                         /* If we can't allocate a large enough buffer
 420                          * for the request, shrink it to a smaller
 421                          * PAGE_SIZE multiple and try again.
 422                          * We should always be able to kmalloc for a
 423                          * page worth of page pointers = 4MB on i386. */
 424                         if (result == -ENOMEM &&
 425                             size > (PAGE_SIZE / sizeof(*pages)) *
 426                                     PAGE_SIZE) {
 427                                 size = ((((size / 2) - 1) |
 428                                         ~PAGE_MASK) + 1) & PAGE_MASK;
 429                                 CDEBUG(D_VFSTRACE, "DIO size now %zu\n",
 430                                        size);
 431                                 continue;
 432                         }
 433
 434                         GOTO(out, result);
 435                 }
 436
 437                 iov_iter_advance(iter, result);
 438                 tot_bytes += result;
 439                 file_offset += result;
 440         }
 441 out:
 442         if (iov_iter_rw(iter) == READ)
 443                 inode_unlock(inode);
 444
 445         if (tot_bytes > 0) {
 446                 struct vvp_io *vio = vvp_env_io(env);
 447
 448                 /* no commit async for direct IO */
 449                 vio->u.write.vui_written += tot_bytes;
 450         }
 451
 452         return tot_bytes ? : result;
 453 }
 454 #else /* !HAVE_DIRECTIO_ITER && !HAVE_IOV_ITER_RW */
 455
 456 static inline int ll_get_user_pages(int rw, unsigned long user_addr,
 457                                     size_t size, struct page ***pages,
 458                                     int *max_pages)
 459 {
 460         int result = -ENOMEM;
 461
 462         /* set an arbitrary limit to prevent arithmetic overflow */
 463         if (size > MAX_DIRECTIO_SIZE) {
 464                 *pages = NULL;
 465                 return -EFBIG;
 466         }
 467
 468         *max_pages = (user_addr + size + PAGE_SIZE - 1) >>
 469                       PAGE_SHIFT;
 470         *max_pages -= user_addr >> PAGE_SHIFT;
 471
 472         OBD_ALLOC_LARGE(*pages, *max_pages * sizeof(**pages));
 473         if (*pages) {
 474                 down_read(&current->mm->mmap_sem);
 475                 result = get_user_pages(current, current->mm, user_addr,
 476                                         *max_pages, (rw == READ), 0, *pages,
 477                                         NULL);
 478                 up_read(&current->mm->mmap_sem);
 479                 if (unlikely(result <= 0))
 480                         OBD_FREE_LARGE(*pages, *max_pages * sizeof(**pages));
 481         }
 482
 483         return result;
 484 }
 485
 486 static ssize_t
 487 ll_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 488              loff_t file_offset, unsigned long nr_segs)
 489 {
 490         struct ll_cl_context *lcc;
 491         const struct lu_env *env;
 492         struct cl_io *io;
 493         struct file *file = iocb->ki_filp;
 494         struct inode *inode = file->f_mapping->host;
 495         ssize_t count = iov_length(iov, nr_segs);
 496         ssize_t tot_bytes = 0, result = 0;
 497         unsigned long seg = 0;
 498         size_t size = MAX_DIO_SIZE;
 499         ENTRY;
 500
 501         /* FIXME: io smaller than PAGE_SIZE is broken on ia64 ??? */
 502         if ((file_offset & ~PAGE_MASK) || (count & ~PAGE_MASK))
 503                 RETURN(-EINVAL);
 504
 505         CDEBUG(D_VFSTRACE, "VFS Op:inode="DFID"(%p), size=%zd (max %lu), "
 506                "offset=%lld=%llx, pages %zd (max %lu)\n",
 507                PFID(ll_inode2fid(inode)), inode, count, MAX_DIO_SIZE,
 508                file_offset, file_offset, count >> PAGE_SHIFT,
 509                MAX_DIO_SIZE >> PAGE_SHIFT);
 510
 511         /* Check that all user buffers are aligned as well */
 512         for (seg = 0; seg < nr_segs; seg++) {
 513                 if (((unsigned long)iov[seg].iov_base & ~PAGE_MASK) ||
 514                     (iov[seg].iov_len & ~PAGE_MASK))
 515                         RETURN(-EINVAL);
 516         }
 517
 518         lcc = ll_cl_find(file);
 519         if (lcc == NULL)
 520                 RETURN(-EIO);
 521
 522         env = lcc->lcc_env;
 523         LASSERT(!IS_ERR(env));
 524         io = lcc->lcc_io;
 525         LASSERT(io != NULL);
 526
 527         for (seg = 0; seg < nr_segs; seg++) {
 528                 size_t iov_left = iov[seg].iov_len;
 529                 unsigned long user_addr = (unsigned long)iov[seg].iov_base;
 530
 531                 if (rw == READ) {
 532                         if (file_offset >= i_size_read(inode))
 533                                 break;
 534                         if (file_offset + iov_left > i_size_read(inode))
 535                                 iov_left = i_size_read(inode) - file_offset;
 536                 }
 537
 538                 while (iov_left > 0) {
 539                         struct page **pages;
 540                         int page_count, max_pages = 0;
 541                         size_t bytes;
 542
 543                         bytes = min(size, iov_left);
 544                         page_count = ll_get_user_pages(rw, user_addr, bytes,
 545                                                        &pages, &max_pages);
 546                         if (likely(page_count > 0)) {
 547                                 if (unlikely(page_count <  max_pages))
 548                                         bytes = page_count << PAGE_SHIFT;
 549                                 result = ll_direct_IO_seg(env, io, rw, inode,
 550                                                           bytes, file_offset,
 551                                                           pages, page_count);
 552                                 ll_free_user_pages(pages, max_pages, rw==READ);
 553                         } else if (page_count == 0) {
 554                                 GOTO(out, result = -EFAULT);
 555                         } else {
 556                                 result = page_count;
 557                         }
 558                         if (unlikely(result <= 0)) {
 559                                 /* If we can't allocate a large enough buffer
 560                                  * for the request, shrink it to a smaller
 561                                  * PAGE_SIZE multiple and try again.
 562                                  * We should always be able to kmalloc for a
 563                                  * page worth of page pointers = 4MB on i386. */
 564                                 if (result == -ENOMEM &&
 565                                     size > (PAGE_SIZE / sizeof(*pages)) *
 566                                            PAGE_SIZE) {
 567                                         size = ((((size / 2) - 1) |
 568                                                  ~PAGE_MASK) + 1) &
 569                                                 PAGE_MASK;
 570                                         CDEBUG(D_VFSTRACE, "DIO size now %zu\n",
 571                                                size);
 572                                         continue;
 573                                 }
 574
 575                                 GOTO(out, result);
 576                         }
 577
 578                         tot_bytes += result;
 579                         file_offset += result;
 580                         iov_left -= result;
 581                         user_addr += result;
 582                 }
 583         }
 584 out:
 585         if (tot_bytes > 0) {
 586                 struct vvp_io *vio = vvp_env_io(env);
 587
 588                 /* no commit async for direct IO */
 589                 vio->u.write.vui_written += tot_bytes;
 590         }
 591
 592         RETURN(tot_bytes ? tot_bytes : result);
 593 }
 594 #endif /* HAVE_DIRECTIO_ITER || HAVE_IOV_ITER_RW */
 595
 596 /**
 597  * Prepare partially written-to page for a write.
 598  */
 599 static int ll_prepare_partial_page(const struct lu_env *env, struct cl_io *io,
 600                                    struct cl_page *pg)
 601 {
 602         struct cl_attr *attr   = vvp_env_thread_attr(env);
 603         struct cl_object *obj  = io->ci_obj;
 604         struct vvp_page *vpg   = cl_object_page_slice(obj, pg);
 605         loff_t          offset = cl_offset(obj, vvp_index(vpg));
 606         int             result;
 607
 608         cl_object_attr_lock(obj);
 609         result = cl_object_attr_get(env, obj, attr);
 610         cl_object_attr_unlock(obj);
 611         if (result == 0) {
 612                 /*
 613                  * If are writing to a new page, no need to read old data.
 614                  * The extent locking will have updated the KMS, and for our
 615                  * purposes here we can treat it like i_size.
 616                  */
 617                 if (attr->cat_kms <= offset) {
 618                         char *kaddr = ll_kmap_atomic(vpg->vpg_page, KM_USER0);
 619
 620                         memset(kaddr, 0, cl_page_size(obj));
 621                         ll_kunmap_atomic(kaddr, KM_USER0);
 622                 } else if (vpg->vpg_defer_uptodate)
 623                         vpg->vpg_ra_used = 1;
 624                 else
 625                         result = ll_page_sync_io(env, io, pg, CRT_READ);
 626         }
 627         return result;
 628 }
 629
 630 static int ll_write_begin(struct file *file, struct address_space *mapping,
 631                           loff_t pos, unsigned len, unsigned flags,
 632                           struct page **pagep, void **fsdata)
 633 {
 634         struct ll_cl_context *lcc;
 635         const struct lu_env  *env;
 636         struct cl_io   *io;
 637         struct cl_page *page;
 638
 639         struct cl_object *clob = ll_i2info(mapping->host)->lli_clob;
 640         pgoff_t index = pos >> PAGE_SHIFT;
 641         struct page *vmpage = NULL;
 642         unsigned from = pos & (PAGE_SIZE - 1);
 643         unsigned to = from + len;
 644         int result = 0;
 645         ENTRY;
 646
 647         CDEBUG(D_VFSTRACE, "Writing %lu of %d to %d bytes\n", index, from, len);
 648
 649         lcc = ll_cl_find(file);
 650         if (lcc == NULL) {
 651                 io = NULL;
 652                 GOTO(out, result = -EIO);
 653         }
 654
 655         env = lcc->lcc_env;
 656         io  = lcc->lcc_io;
 657
 658         /* To avoid deadlock, try to lock page first. */
 659         vmpage = grab_cache_page_nowait(mapping, index);
 660
 661         if (unlikely(vmpage == NULL ||
 662                      PageDirty(vmpage) || PageWriteback(vmpage))) {
 663                 struct vvp_io *vio = vvp_env_io(env);
 664                 struct cl_page_list *plist = &vio->u.write.vui_queue;
 665
 666                 /* if the page is already in dirty cache, we have to commit
 667                  * the pages right now; otherwise, it may cause deadlock
 668                  * because it holds page lock of a dirty page and request for
 669                  * more grants. It's okay for the dirty page to be the first
 670                  * one in commit page list, though. */
 671                 if (vmpage != NULL && plist->pl_nr > 0) {
 672                         unlock_page(vmpage);
 673                         page_cache_release(vmpage);
 674                         vmpage = NULL;
 675                 }
 676
 677                 /* commit pages and then wait for page lock */
 678                 result = vvp_io_write_commit(env, io);
 679                 if (result < 0)
 680                         GOTO(out, result);
 681
 682                 if (vmpage == NULL) {
 683                         vmpage = grab_cache_page_write_begin(mapping, index,
 684                                                              flags);
 685                         if (vmpage == NULL)
 686                                 GOTO(out, result = -ENOMEM);
 687                 }
 688         }
 689
 690         page = cl_page_find(env, clob, vmpage->index, vmpage, CPT_CACHEABLE);
 691         if (IS_ERR(page))
 692                 GOTO(out, result = PTR_ERR(page));
 693
 694         lcc->lcc_page = page;
 695         lu_ref_add(&page->cp_reference, "cl_io", io);
 696
 697         cl_page_assume(env, io, page);
 698         if (!PageUptodate(vmpage)) {
 699                 /*
 700                  * We're completely overwriting an existing page,
 701                  * so _don't_ set it up to date until commit_write
 702                  */
 703                 if (from == 0 && to == PAGE_SIZE) {
 704                         CL_PAGE_HEADER(D_PAGE, env, page, "full page write\n");
 705                         POISON_PAGE(vmpage, 0x11);
 706                 } else {
 707                         /* TODO: can be optimized at OSC layer to check if it
 708                          * is a lockless IO. In that case, it's not necessary
 709                          * to read the data. */
 710                         result = ll_prepare_partial_page(env, io, page);
 711                         if (result == 0)
 712                                 SetPageUptodate(vmpage);
 713                 }
 714         }
 715         if (result < 0)
 716                 cl_page_unassume(env, io, page);
 717         EXIT;
 718 out:
 719         if (result < 0) {
 720                 if (vmpage != NULL) {
 721                         unlock_page(vmpage);
 722                         page_cache_release(vmpage);
 723                 }
 724                 if (io)
 725                         io->ci_result = result;
 726         } else {
 727                 *pagep = vmpage;
 728                 *fsdata = lcc;
 729         }
 730         RETURN(result);
 731 }
 732
 733 static int ll_write_end(struct file *file, struct address_space *mapping,
 734                         loff_t pos, unsigned len, unsigned copied,
 735                         struct page *vmpage, void *fsdata)
 736 {
 737         struct ll_cl_context *lcc = fsdata;
 738         const struct lu_env *env;
 739         struct cl_io *io;
 740         struct vvp_io *vio;
 741         struct cl_page *page;
 742         unsigned from = pos & (PAGE_SIZE - 1);
 743         bool unplug = false;
 744         int result = 0;
 745         ENTRY;
 746
 747         page_cache_release(vmpage);
 748
 749         LASSERT(lcc != NULL);
 750         env  = lcc->lcc_env;
 751         page = lcc->lcc_page;
 752         io   = lcc->lcc_io;
 753         vio  = vvp_env_io(env);
 754
 755         LASSERT(cl_page_is_owned(page, io));
 756         if (copied > 0) {
 757                 struct cl_page_list *plist = &vio->u.write.vui_queue;
 758
 759                 lcc->lcc_page = NULL; /* page will be queued */
 760
 761                 /* Add it into write queue */
 762                 cl_page_list_add(plist, page);
 763                 if (plist->pl_nr == 1) /* first page */
 764                         vio->u.write.vui_from = from;
 765                 else
 766                         LASSERT(from == 0);
 767                 vio->u.write.vui_to = from + copied;
 768
 769                 /* To address the deadlock in balance_dirty_pages() where
 770                  * this dirty page may be written back in the same thread. */
 771                 if (PageDirty(vmpage))
 772                         unplug = true;
 773
 774                 /* We may have one full RPC, commit it soon */
 775                 if (plist->pl_nr >= PTLRPC_MAX_BRW_PAGES)
 776                         unplug = true;
 777
 778                 CL_PAGE_DEBUG(D_VFSTRACE, env, page,
 779                               "queued page: %d.\n", plist->pl_nr);
 780         } else {
 781                 cl_page_disown(env, io, page);
 782
 783                 lcc->lcc_page = NULL;
 784                 lu_ref_del(&page->cp_reference, "cl_io", io);
 785                 cl_page_put(env, page);
 786
 787                 /* page list is not contiguous now, commit it now */
 788                 unplug = true;
 789         }
 790         if (unplug ||
 791             file->f_flags & O_SYNC || IS_SYNC(file_inode(file)))
 792                 result = vvp_io_write_commit(env, io);
 793
 794         if (result < 0)
 795                 io->ci_result = result;
 796         RETURN(result >= 0 ? copied : result);
 797 }
 798
 799 #ifdef CONFIG_MIGRATION
 800 static int ll_migratepage(struct address_space *mapping,
 801                           struct page *newpage, struct page *page
 802 #ifdef HAVE_MIGRATEPAGE_4ARGS
 803                           , enum migrate_mode mode
 804 #endif
 805         )
 806 {
 807         /* Always fail page migration until we have a proper implementation */
 808         return -EIO;
 809 }
 810 #endif
 811
 812 const struct address_space_operations ll_aops = {
 813         .readpage       = ll_readpage,
 814         .direct_IO      = ll_direct_IO,
 815         .writepage      = ll_writepage,
 816         .writepages     = ll_writepages,
 817         .set_page_dirty = __set_page_dirty_nobuffers,
 818         .write_begin    = ll_write_begin,
 819         .write_end      = ll_write_end,
 820         .invalidatepage = ll_invalidatepage,
 821         .releasepage    = (void *)ll_releasepage,
 822 #ifdef CONFIG_MIGRATION
 823         .migratepage    = ll_migratepage,
 824 #endif
 825 };