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.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2011, 2017, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  * Lustre is a trademark of Sun Microsystems, Inc.
  31  *
  32  * lustre/lustre/llite/rw26.c
  33  *
  34  * Lustre Lite I/O page cache routines for the 2.5/2.6 kernel version
  35  */
  36
  37 #include <linux/buffer_head.h>
  38 #include <linux/errno.h>
  39 #include <linux/fs.h>
  40 #include <linux/kernel.h>
  41 #include <linux/mm.h>
  42 #include <linux/mpage.h>
  43 #include <linux/pagemap.h>
  44 #include <linux/string.h>
  45 #include <linux/unistd.h>
  46 #include <linux/writeback.h>
  47
  48 #ifdef HAVE_MIGRATE_H
  49 #include <linux/migrate.h>
  50 #elif defined(HAVE_MIGRATE_MODE_H)
  51 #include <linux/migrate_mode.h>
  52 #endif
  53
  54 #define DEBUG_SUBSYSTEM S_LLITE
  55
  56 #include "llite_internal.h"
  57 #include <lustre_compat.h>
  58
  59 /**
  60  * Implements Linux VM address_space::invalidatepage() method. This method is
  61  * called when the page is truncate from a file, either as a result of
  62  * explicit truncate, or when inode is removed from memory (as a result of
  63  * final iput(), umount, or memory pressure induced icache shrinking).
  64  *
  65  * [0, offset] bytes of the page remain valid (this is for a case of not-page
  66  * aligned truncate). Lustre leaves partially truncated page in the cache,
  67  * relying on struct inode::i_size to limit further accesses.
  68  */
  69 static void ll_invalidatepage(struct page *vmpage,
  70 #ifdef HAVE_INVALIDATE_RANGE
  71                                 unsigned int offset, unsigned int length
  72 #else
  73                                 unsigned long offset
  74 #endif
  75                              )
  76 {
  77         struct inode     *inode;
  78         struct lu_env    *env;
  79         struct cl_page   *page;
  80         struct cl_object *obj;
  81
  82         LASSERT(PageLocked(vmpage));
  83         LASSERT(!PageWriteback(vmpage));
  84
  85         /*
  86          * It is safe to not check anything in invalidatepage/releasepage
  87          * below because they are run with page locked and all our io is
  88          * happening with locked page too
  89          */
  90 #ifdef HAVE_INVALIDATE_RANGE
  91         if (offset == 0 && length == PAGE_SIZE) {
  92 #else
  93         if (offset == 0) {
  94 #endif
  95                 /* See the comment in ll_releasepage() */
  96                 env = cl_env_percpu_get();
  97                 LASSERT(!IS_ERR(env));
  98
  99                 inode = vmpage->mapping->host;
 100                 obj = ll_i2info(inode)->lli_clob;
 101                 if (obj != NULL) {
 102                         page = cl_vmpage_page(vmpage, obj);
 103                         if (page != NULL) {
 104                                 cl_page_delete(env, page);
 105                                 cl_page_put(env, page);
 106                         }
 107                 } else
 108                         LASSERT(vmpage->private == 0);
 109
 110                 cl_env_percpu_put(env);
 111         }
 112 }
 113
 114 #ifdef HAVE_RELEASEPAGE_WITH_INT
 115 #define RELEASEPAGE_ARG_TYPE int
 116 #else
 117 #define RELEASEPAGE_ARG_TYPE gfp_t
 118 #endif
 119 static int ll_releasepage(struct page *vmpage, RELEASEPAGE_ARG_TYPE gfp_mask)
 120 {
 121         struct lu_env           *env;
 122         struct cl_object        *obj;
 123         struct cl_page          *page;
 124         struct address_space    *mapping;
 125         int result = 0;
 126
 127         LASSERT(PageLocked(vmpage));
 128         if (PageWriteback(vmpage) || PageDirty(vmpage))
 129                 return 0;
 130
 131         mapping = vmpage->mapping;
 132         if (mapping == NULL)
 133                 return 1;
 134
 135         obj = ll_i2info(mapping->host)->lli_clob;
 136         if (obj == NULL)
 137                 return 1;
 138
 139         page = cl_vmpage_page(vmpage, obj);
 140         if (page == NULL)
 141                 return 1;
 142
 143         env = cl_env_percpu_get();
 144         LASSERT(!IS_ERR(env));
 145
 146         if (!cl_page_in_use(page)) {
 147                 result = 1;
 148                 cl_page_delete(env, page);
 149         }
 150
 151         /* To use percpu env array, the call path can not be rescheduled;
 152          * otherwise percpu array will be messed if ll_releaspage() called
 153          * again on the same CPU.
 154          *
 155          * If this page holds the last refc of cl_object, the following
 156          * call path may cause reschedule:
 157          *   cl_page_put -> cl_page_free -> cl_object_put ->
 158          *     lu_object_put -> lu_object_free -> lov_delete_raid0.
 159          *
 160          * However, the kernel can't get rid of this inode until all pages have
 161          * been cleaned up. Now that we hold page lock here, it's pretty safe
 162          * that we won't get into object delete path.
 163          */
 164         LASSERT(cl_object_refc(obj) > 1);
 165         cl_page_put(env, page);
 166
 167         cl_env_percpu_put(env);
 168         return result;
 169 }
 170
 171 #define MAX_DIRECTIO_SIZE 2*1024*1024*1024UL
 172
 173 static ssize_t
 174 ll_direct_IO_seg(const struct lu_env *env, struct cl_io *io, int rw,
 175                  struct inode *inode, size_t size, loff_t file_offset,
 176                  struct page **pages, int page_count)
 177 {
 178         struct cl_page *clp;
 179         struct cl_2queue *queue;
 180         struct cl_object *obj = io->ci_obj;
 181         int i;
 182         ssize_t rc = 0;
 183         size_t page_size = cl_page_size(obj);
 184         size_t orig_size = size;
 185         bool do_io;
 186         int io_pages = 0;
 187
 188         ENTRY;
 189         queue = &io->ci_queue;
 190         cl_2queue_init(queue);
 191         for (i = 0; i < page_count; i++) {
 192                 LASSERT(!(file_offset & (page_size - 1)));
 193                 clp = cl_page_find(env, obj, cl_index(obj, file_offset),
 194                                    pages[i], CPT_TRANSIENT);
 195                 if (IS_ERR(clp)) {
 196                         rc = PTR_ERR(clp);
 197                         break;
 198                 }
 199
 200                 rc = cl_page_own(env, io, clp);
 201                 if (rc) {
 202                         LASSERT(clp->cp_state == CPS_FREEING);
 203                         cl_page_put(env, clp);
 204                         break;
 205                 }
 206
 207                 do_io = true;
 208
 209                 /* check the page type: if the page is a host page, then do
 210                  * write directly
 211                  */
 212                 if (clp->cp_type == CPT_CACHEABLE) {
 213                         struct page *vmpage = cl_page_vmpage(clp);
 214                         struct page *src_page;
 215                         struct page *dst_page;
 216                         void *src;
 217                         void *dst;
 218
 219                         src_page = (rw == WRITE) ? pages[i] : vmpage;
 220                         dst_page = (rw == WRITE) ? vmpage : pages[i];
 221
 222                         src = ll_kmap_atomic(src_page, KM_USER0);
 223                         dst = ll_kmap_atomic(dst_page, KM_USER1);
 224                         memcpy(dst, src, min(page_size, size));
 225                         ll_kunmap_atomic(dst, KM_USER1);
 226                         ll_kunmap_atomic(src, KM_USER0);
 227
 228                         /* make sure page will be added to the transfer by
 229                          * cl_io_submit()->...->vvp_page_prep_write().
 230                          */
 231                         if (rw == WRITE)
 232                                 set_page_dirty(vmpage);
 233
 234                         if (rw == READ) {
 235                                 /* do not issue the page for read, since it
 236                                  * may reread a ra page which has NOT uptodate
 237                                  * bit set.
 238                                  */
 239                                 cl_page_disown(env, io, clp);
 240                                 do_io = false;
 241                         }
 242                 }
 243
 244                 if (likely(do_io)) {
 245                         cl_2queue_add(queue, clp);
 246
 247                         /*
 248                          * Set page clip to tell transfer formation engine
 249                          * that page has to be sent even if it is beyond KMS.
 250                          */
 251                         cl_page_clip(env, clp, 0, min(size, page_size));
 252
 253                         ++io_pages;
 254                 }
 255
 256                 /* drop the reference count for cl_page_find */
 257                 cl_page_put(env, clp);
 258                 size -= page_size;
 259                 file_offset += page_size;
 260         }
 261
 262         if (rc == 0 && io_pages) {
 263                 rc = cl_io_submit_sync(env, io,
 264                                        rw == READ ? CRT_READ : CRT_WRITE,
 265                                        queue, 0);
 266         }
 267         if (rc == 0)
 268                 rc = orig_size;
 269
 270         cl_2queue_discard(env, io, queue);
 271         cl_2queue_disown(env, io, queue);
 272         cl_2queue_fini(env, queue);
 273         RETURN(rc);
 274 }
 275
 276 /*  ll_free_user_pages - tear down page struct array
 277  *  @pages: array of page struct pointers underlying target buffer */
 278 static void ll_free_user_pages(struct page **pages, int npages, int do_dirty)
 279 {
 280         int i;
 281
 282         for (i = 0; i < npages; i++) {
 283                 if (pages[i] == NULL)
 284                         break;
 285                 if (do_dirty)
 286                         set_page_dirty_lock(pages[i]);
 287                 put_page(pages[i]);
 288         }
 289
 290 #if defined(HAVE_DIRECTIO_ITER) || defined(HAVE_IOV_ITER_RW)
 291         kvfree(pages);
 292 #else
 293         OBD_FREE_LARGE(pages, npages * sizeof(*pages));
 294 #endif
 295 }
 296
 297 #ifdef KMALLOC_MAX_SIZE
 298 #define MAX_MALLOC KMALLOC_MAX_SIZE
 299 #else
 300 #define MAX_MALLOC (128 * 1024)
 301 #endif
 302
 303 /* This is the maximum size of a single O_DIRECT request, based on the
 304  * kmalloc limit.  We need to fit all of the brw_page structs, each one
 305  * representing PAGE_SIZE worth of user data, into a single buffer, and
 306  * then truncate this to be a full-sized RPC.  For 4kB PAGE_SIZE this is
 307  * up to 22MB for 128kB kmalloc and up to 682MB for 4MB kmalloc. */
 308 #define MAX_DIO_SIZE ((MAX_MALLOC / sizeof(struct brw_page) * PAGE_SIZE) & \
 309                       ~(DT_MAX_BRW_SIZE - 1))
 310
 311 #ifndef HAVE_IOV_ITER_RW
 312 # define iov_iter_rw(iter)      rw
 313 #endif
 314
 315 #if defined(HAVE_DIRECTIO_ITER) || defined(HAVE_IOV_ITER_RW)
 316 static ssize_t
 317 ll_direct_IO(
 318 # ifndef HAVE_IOV_ITER_RW
 319              int rw,
 320 # endif
 321              struct kiocb *iocb, struct iov_iter *iter
 322 # ifndef HAVE_DIRECTIO_2ARGS
 323              , loff_t file_offset
 324 # endif
 325              )
 326 {
 327 #ifdef HAVE_DIRECTIO_2ARGS
 328         loff_t file_offset = iocb->ki_pos;
 329 #endif
 330         struct ll_cl_context *lcc;
 331         const struct lu_env *env;
 332         struct cl_io *io;
 333         struct file *file = iocb->ki_filp;
 334         struct inode *inode = file->f_mapping->host;
 335         ssize_t count = iov_iter_count(iter);
 336         ssize_t tot_bytes = 0, result = 0;
 337         size_t size = MAX_DIO_SIZE;
 338
 339         /* Check EOF by ourselves */
 340         if (iov_iter_rw(iter) == READ && file_offset >= i_size_read(inode))
 341                 return 0;
 342         /* FIXME: io smaller than PAGE_SIZE is broken on ia64 ??? */
 343         if ((file_offset & ~PAGE_MASK) || (count & ~PAGE_MASK))
 344                 return -EINVAL;
 345
 346         CDEBUG(D_VFSTRACE, "VFS Op:inode="DFID"(%p), size=%zd (max %lu), "
 347                "offset=%lld=%llx, pages %zd (max %lu)\n",
 348                PFID(ll_inode2fid(inode)), inode, count, MAX_DIO_SIZE,
 349                file_offset, file_offset, count >> PAGE_SHIFT,
 350                MAX_DIO_SIZE >> PAGE_SHIFT);
 351
 352         /* Check that all user buffers are aligned as well */
 353         if (iov_iter_alignment(iter) & ~PAGE_MASK)
 354                 return -EINVAL;
 355
 356         lcc = ll_cl_find(file);
 357         if (lcc == NULL)
 358                 RETURN(-EIO);
 359
 360         env = lcc->lcc_env;
 361         LASSERT(!IS_ERR(env));
 362         io = lcc->lcc_io;
 363         LASSERT(io != NULL);
 364
 365         /* 0. Need locking between buffered and direct access. and race with
 366          *    size changing by concurrent truncates and writes.
 367          * 1. Need inode mutex to operate transient pages.
 368          */
 369         if (iov_iter_rw(iter) == READ)
 370                 inode_lock(inode);
 371
 372         while (iov_iter_count(iter)) {
 373                 struct page **pages;
 374                 size_t offs;
 375
 376                 count = min_t(size_t, iov_iter_count(iter), size);
 377                 if (iov_iter_rw(iter) == READ) {
 378                         if (file_offset >= i_size_read(inode))
 379                                 break;
 380
 381                         if (file_offset + count > i_size_read(inode))
 382                                 count = i_size_read(inode) - file_offset;
 383                 }
 384
 385                 result = iov_iter_get_pages_alloc(iter, &pages, count, &offs);
 386                 if (likely(result > 0)) {
 387                         int n = DIV_ROUND_UP(result + offs, PAGE_SIZE);
 388
 389                         result = ll_direct_IO_seg(env, io, iov_iter_rw(iter),
 390                                                   inode, result, file_offset,
 391                                                   pages, n);
 392                         ll_free_user_pages(pages, n,
 393                                            iov_iter_rw(iter) == READ);
 394
 395                 }
 396                 if (unlikely(result <= 0)) {
 397                         /* If we can't allocate a large enough buffer
 398                          * for the request, shrink it to a smaller
 399                          * PAGE_SIZE multiple and try again.
 400                          * We should always be able to kmalloc for a
 401                          * page worth of page pointers = 4MB on i386. */
 402                         if (result == -ENOMEM &&
 403                             size > (PAGE_SIZE / sizeof(*pages)) *
 404                                     PAGE_SIZE) {
 405                                 size = ((((size / 2) - 1) |
 406                                         ~PAGE_MASK) + 1) & PAGE_MASK;
 407                                 CDEBUG(D_VFSTRACE, "DIO size now %zu\n",
 408                                        size);
 409                                 continue;
 410                         }
 411
 412                         GOTO(out, result);
 413                 }
 414
 415                 iov_iter_advance(iter, result);
 416                 tot_bytes += result;
 417                 file_offset += result;
 418         }
 419 out:
 420         if (iov_iter_rw(iter) == READ)
 421                 inode_unlock(inode);
 422
 423         if (tot_bytes > 0) {
 424                 struct vvp_io *vio = vvp_env_io(env);
 425
 426                 /* no commit async for direct IO */
 427                 vio->u.write.vui_written += tot_bytes;
 428         }
 429
 430         return tot_bytes ? : result;
 431 }
 432 #else /* !HAVE_DIRECTIO_ITER && !HAVE_IOV_ITER_RW */
 433
 434 static inline int ll_get_user_pages(int rw, unsigned long user_addr,
 435                                     size_t size, struct page ***pages,
 436                                     int *max_pages)
 437 {
 438         int result = -ENOMEM;
 439
 440         /* set an arbitrary limit to prevent arithmetic overflow */
 441         if (size > MAX_DIRECTIO_SIZE) {
 442                 *pages = NULL;
 443                 return -EFBIG;
 444         }
 445
 446         *max_pages = (user_addr + size + PAGE_SIZE - 1) >>
 447                       PAGE_SHIFT;
 448         *max_pages -= user_addr >> PAGE_SHIFT;
 449
 450         OBD_ALLOC_LARGE(*pages, *max_pages * sizeof(**pages));
 451         if (*pages) {
 452                 down_read(&current->mm->mmap_sem);
 453                 result = get_user_pages(current, current->mm, user_addr,
 454                                         *max_pages, (rw == READ), 0, *pages,
 455                                         NULL);
 456                 up_read(&current->mm->mmap_sem);
 457                 if (unlikely(result <= 0))
 458                         OBD_FREE_LARGE(*pages, *max_pages * sizeof(**pages));
 459         }
 460
 461         return result;
 462 }
 463
 464 static ssize_t
 465 ll_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 466              loff_t file_offset, unsigned long nr_segs)
 467 {
 468         struct ll_cl_context *lcc;
 469         const struct lu_env *env;
 470         struct cl_io *io;
 471         struct file *file = iocb->ki_filp;
 472         struct inode *inode = file->f_mapping->host;
 473         ssize_t count = iov_length(iov, nr_segs);
 474         ssize_t tot_bytes = 0, result = 0;
 475         unsigned long seg = 0;
 476         size_t size = MAX_DIO_SIZE;
 477         ENTRY;
 478
 479         /* FIXME: io smaller than PAGE_SIZE is broken on ia64 ??? */
 480         if ((file_offset & ~PAGE_MASK) || (count & ~PAGE_MASK))
 481                 RETURN(-EINVAL);
 482
 483         CDEBUG(D_VFSTRACE, "VFS Op:inode="DFID"(%p), size=%zd (max %lu), "
 484                "offset=%lld=%llx, pages %zd (max %lu)\n",
 485                PFID(ll_inode2fid(inode)), inode, count, MAX_DIO_SIZE,
 486                file_offset, file_offset, count >> PAGE_SHIFT,
 487                MAX_DIO_SIZE >> PAGE_SHIFT);
 488
 489         /* Check that all user buffers are aligned as well */
 490         for (seg = 0; seg < nr_segs; seg++) {
 491                 if (((unsigned long)iov[seg].iov_base & ~PAGE_MASK) ||
 492                     (iov[seg].iov_len & ~PAGE_MASK))
 493                         RETURN(-EINVAL);
 494         }
 495
 496         lcc = ll_cl_find(file);
 497         if (lcc == NULL)
 498                 RETURN(-EIO);
 499
 500         env = lcc->lcc_env;
 501         LASSERT(!IS_ERR(env));
 502         io = lcc->lcc_io;
 503         LASSERT(io != NULL);
 504
 505         for (seg = 0; seg < nr_segs; seg++) {
 506                 size_t iov_left = iov[seg].iov_len;
 507                 unsigned long user_addr = (unsigned long)iov[seg].iov_base;
 508
 509                 if (rw == READ) {
 510                         if (file_offset >= i_size_read(inode))
 511                                 break;
 512                         if (file_offset + iov_left > i_size_read(inode))
 513                                 iov_left = i_size_read(inode) - file_offset;
 514                 }
 515
 516                 while (iov_left > 0) {
 517                         struct page **pages;
 518                         int page_count, max_pages = 0;
 519                         size_t bytes;
 520
 521                         bytes = min(size, iov_left);
 522                         page_count = ll_get_user_pages(rw, user_addr, bytes,
 523                                                        &pages, &max_pages);
 524                         if (likely(page_count > 0)) {
 525                                 if (unlikely(page_count <  max_pages))
 526                                         bytes = page_count << PAGE_SHIFT;
 527                                 result = ll_direct_IO_seg(env, io, rw, inode,
 528                                                           bytes, file_offset,
 529                                                           pages, page_count);
 530                                 ll_free_user_pages(pages, max_pages, rw==READ);
 531                         } else if (page_count == 0) {
 532                                 GOTO(out, result = -EFAULT);
 533                         } else {
 534                                 result = page_count;
 535                         }
 536                         if (unlikely(result <= 0)) {
 537                                 /* If we can't allocate a large enough buffer
 538                                  * for the request, shrink it to a smaller
 539                                  * PAGE_SIZE multiple and try again.
 540                                  * We should always be able to kmalloc for a
 541                                  * page worth of page pointers = 4MB on i386. */
 542                                 if (result == -ENOMEM &&
 543                                     size > (PAGE_SIZE / sizeof(*pages)) *
 544                                            PAGE_SIZE) {
 545                                         size = ((((size / 2) - 1) |
 546                                                  ~PAGE_MASK) + 1) &
 547                                                 PAGE_MASK;
 548                                         CDEBUG(D_VFSTRACE, "DIO size now %zu\n",
 549                                                size);
 550                                         continue;
 551                                 }
 552
 553                                 GOTO(out, result);
 554                         }
 555
 556                         tot_bytes += result;
 557                         file_offset += result;
 558                         iov_left -= result;
 559                         user_addr += result;
 560                 }
 561         }
 562 out:
 563         if (tot_bytes > 0) {
 564                 struct vvp_io *vio = vvp_env_io(env);
 565
 566                 /* no commit async for direct IO */
 567                 vio->u.write.vui_written += tot_bytes;
 568         }
 569
 570         RETURN(tot_bytes ? tot_bytes : result);
 571 }
 572 #endif /* HAVE_DIRECTIO_ITER || HAVE_IOV_ITER_RW */
 573
 574 /**
 575  * Prepare partially written-to page for a write.
 576  * @pg is owned when passed in and disowned when it returns non-zero result to
 577  * the caller.
 578  */
 579 static int ll_prepare_partial_page(const struct lu_env *env, struct cl_io *io,
 580                                    struct cl_page *pg, struct file *file)
 581 {
 582         struct cl_attr *attr   = vvp_env_thread_attr(env);
 583         struct cl_object *obj  = io->ci_obj;
 584         struct vvp_page *vpg   = cl_object_page_slice(obj, pg);
 585         loff_t          offset = cl_offset(obj, vvp_index(vpg));
 586         int             result;
 587         ENTRY;
 588
 589         cl_object_attr_lock(obj);
 590         result = cl_object_attr_get(env, obj, attr);
 591         cl_object_attr_unlock(obj);
 592         if (result) {
 593                 cl_page_disown(env, io, pg);
 594                 GOTO(out, result);
 595         }
 596
 597         /*
 598          * If are writing to a new page, no need to read old data.
 599          * The extent locking will have updated the KMS, and for our
 600          * purposes here we can treat it like i_size.
 601          */
 602         if (attr->cat_kms <= offset) {
 603                 char *kaddr = ll_kmap_atomic(vpg->vpg_page, KM_USER0);
 604
 605                 memset(kaddr, 0, cl_page_size(obj));
 606                 ll_kunmap_atomic(kaddr, KM_USER0);
 607                 GOTO(out, result = 0);
 608         }
 609
 610         if (vpg->vpg_defer_uptodate) {
 611                 vpg->vpg_ra_used = 1;
 612                 GOTO(out, result = 0);
 613         }
 614
 615         result = ll_io_read_page(env, io, pg, file);
 616         if (result)
 617                 GOTO(out, result);
 618
 619         /* ll_io_read_page() disowns the page */
 620         result = cl_page_own(env, io, pg);
 621         if (!result) {
 622                 if (!PageUptodate(cl_page_vmpage(pg))) {
 623                         cl_page_disown(env, io, pg);
 624                         result = -EIO;
 625                 }
 626         } else if (result == -ENOENT) {
 627                 /* page was truncated */
 628                 result = -EAGAIN;
 629         }
 630         EXIT;
 631
 632 out:
 633         return result;
 634 }
 635
 636 static int ll_tiny_write_begin(struct page *vmpage)
 637 {
 638         /* Page must be present, up to date, dirty, and not in writeback. */
 639         if (!vmpage || !PageUptodate(vmpage) || !PageDirty(vmpage) ||
 640             PageWriteback(vmpage))
 641                 return -ENODATA;
 642
 643         return 0;
 644 }
 645
 646 static int ll_write_begin(struct file *file, struct address_space *mapping,
 647                           loff_t pos, unsigned len, unsigned flags,
 648                           struct page **pagep, void **fsdata)
 649 {
 650         struct ll_cl_context *lcc = NULL;
 651         const struct lu_env  *env = NULL;
 652         struct cl_io   *io = NULL;
 653         struct cl_page *page = NULL;
 654
 655         struct cl_object *clob = ll_i2info(mapping->host)->lli_clob;
 656         pgoff_t index = pos >> PAGE_SHIFT;
 657         struct page *vmpage = NULL;
 658         unsigned from = pos & (PAGE_SIZE - 1);
 659         unsigned to = from + len;
 660         int result = 0;
 661         ENTRY;
 662
 663         CDEBUG(D_VFSTRACE, "Writing %lu of %d to %d bytes\n", index, from, len);
 664
 665         lcc = ll_cl_find(file);
 666         if (lcc == NULL) {
 667                 vmpage = grab_cache_page_nowait(mapping, index);
 668                 result = ll_tiny_write_begin(vmpage);
 669                 GOTO(out, result);
 670         }
 671
 672         env = lcc->lcc_env;
 673         io  = lcc->lcc_io;
 674
 675         if (file->f_flags & O_DIRECT && io->ci_designated_mirror > 0) {
 676                 /* direct IO failed because it couldn't clean up cached pages,
 677                  * this causes a problem for mirror write because the cached
 678                  * page may belong to another mirror, which will result in
 679                  * problem submitting the I/O. */
 680                 GOTO(out, result = -EBUSY);
 681         }
 682
 683 again:
 684         /* To avoid deadlock, try to lock page first. */
 685         vmpage = grab_cache_page_nowait(mapping, index);
 686
 687         if (unlikely(vmpage == NULL ||
 688                      PageDirty(vmpage) || PageWriteback(vmpage))) {
 689                 struct vvp_io *vio = vvp_env_io(env);
 690                 struct cl_page_list *plist = &vio->u.write.vui_queue;
 691
 692                 /* if the page is already in dirty cache, we have to commit
 693                  * the pages right now; otherwise, it may cause deadlock
 694                  * because it holds page lock of a dirty page and request for
 695                  * more grants. It's okay for the dirty page to be the first
 696                  * one in commit page list, though. */
 697                 if (vmpage != NULL && plist->pl_nr > 0) {
 698                         unlock_page(vmpage);
 699                         put_page(vmpage);
 700                         vmpage = NULL;
 701                 }
 702
 703                 /* commit pages and then wait for page lock */
 704                 result = vvp_io_write_commit(env, io);
 705                 if (result < 0)
 706                         GOTO(out, result);
 707
 708                 if (vmpage == NULL) {
 709                         vmpage = grab_cache_page_write_begin(mapping, index,
 710                                                              flags);
 711                         if (vmpage == NULL)
 712                                 GOTO(out, result = -ENOMEM);
 713                 }
 714         }
 715
 716         page = cl_page_find(env, clob, vmpage->index, vmpage, CPT_CACHEABLE);
 717         if (IS_ERR(page))
 718                 GOTO(out, result = PTR_ERR(page));
 719
 720         lcc->lcc_page = page;
 721         lu_ref_add(&page->cp_reference, "cl_io", io);
 722
 723         cl_page_assume(env, io, page);
 724         if (!PageUptodate(vmpage)) {
 725                 /*
 726                  * We're completely overwriting an existing page,
 727                  * so _don't_ set it up to date until commit_write
 728                  */
 729                 if (from == 0 && to == PAGE_SIZE) {
 730                         CL_PAGE_HEADER(D_PAGE, env, page, "full page write\n");
 731                         POISON_PAGE(vmpage, 0x11);
 732                 } else {
 733                         /* TODO: can be optimized at OSC layer to check if it
 734                          * is a lockless IO. In that case, it's not necessary
 735                          * to read the data. */
 736                         result = ll_prepare_partial_page(env, io, page, file);
 737                         if (result) {
 738                                 /* vmpage should have been unlocked */
 739                                 put_page(vmpage);
 740                                 vmpage = NULL;
 741
 742                                 if (result == -EAGAIN)
 743                                         goto again;
 744                                 GOTO(out, result);
 745                         }
 746                 }
 747         }
 748         EXIT;
 749 out:
 750         if (result < 0) {
 751                 if (vmpage != NULL) {
 752                         unlock_page(vmpage);
 753                         put_page(vmpage);
 754                 }
 755                 /* On tiny_write failure, page and io are always null. */
 756                 if (!IS_ERR_OR_NULL(page)) {
 757                         lu_ref_del(&page->cp_reference, "cl_io", io);
 758                         cl_page_put(env, page);
 759                 }
 760                 if (io)
 761                         io->ci_result = result;
 762         } else {
 763                 *pagep = vmpage;
 764                 *fsdata = lcc;
 765         }
 766         RETURN(result);
 767 }
 768
 769 static int ll_tiny_write_end(struct file *file, struct address_space *mapping,
 770                              loff_t pos, unsigned int len, unsigned int copied,
 771                              struct page *vmpage)
 772 {
 773         struct cl_page *clpage = (struct cl_page *) vmpage->private;
 774         loff_t kms = pos+copied;
 775         loff_t to = kms & (PAGE_SIZE-1) ? kms & (PAGE_SIZE-1) : PAGE_SIZE;
 776         __u16 refcheck;
 777         struct lu_env *env = cl_env_get(&refcheck);
 778         int rc = 0;
 779
 780         ENTRY;
 781
 782         if (IS_ERR(env)) {
 783                 rc = PTR_ERR(env);
 784                 goto out;
 785         }
 786
 787         /* This page is dirty in cache, so it should have a cl_page pointer
 788          * set in vmpage->private.
 789          */
 790         LASSERT(clpage != NULL);
 791
 792         if (copied == 0)
 793                 goto out_env;
 794
 795         /* Update the underlying size information in the OSC/LOV objects this
 796          * page is part of.
 797          */
 798         cl_page_touch(env, clpage, to);
 799
 800 out_env:
 801         cl_env_put(env, &refcheck);
 802
 803 out:
 804         /* Must return page unlocked. */
 805         unlock_page(vmpage);
 806
 807         RETURN(rc);
 808 }
 809
 810 static int ll_write_end(struct file *file, struct address_space *mapping,
 811                         loff_t pos, unsigned len, unsigned copied,
 812                         struct page *vmpage, void *fsdata)
 813 {
 814         struct ll_cl_context *lcc = fsdata;
 815         const struct lu_env *env;
 816         struct cl_io *io;
 817         struct vvp_io *vio;
 818         struct cl_page *page;
 819         unsigned from = pos & (PAGE_SIZE - 1);
 820         bool unplug = false;
 821         int result = 0;
 822         ENTRY;
 823
 824         put_page(vmpage);
 825
 826         CDEBUG(D_VFSTRACE, "pos %llu, len %u, copied %u\n", pos, len, copied);
 827
 828         if (lcc == NULL) {
 829                 result = ll_tiny_write_end(file, mapping, pos, len, copied,
 830                                            vmpage);
 831                 GOTO(out, result);
 832         }
 833
 834         LASSERT(lcc != NULL);
 835         env  = lcc->lcc_env;
 836         page = lcc->lcc_page;
 837         io   = lcc->lcc_io;
 838         vio  = vvp_env_io(env);
 839
 840         LASSERT(cl_page_is_owned(page, io));
 841         if (copied > 0) {
 842                 struct cl_page_list *plist = &vio->u.write.vui_queue;
 843
 844                 lcc->lcc_page = NULL; /* page will be queued */
 845
 846                 /* Add it into write queue */
 847                 cl_page_list_add(plist, page);
 848                 if (plist->pl_nr == 1) /* first page */
 849                         vio->u.write.vui_from = from;
 850                 else
 851                         LASSERT(from == 0);
 852                 vio->u.write.vui_to = from + copied;
 853
 854                 /* To address the deadlock in balance_dirty_pages() where
 855                  * this dirty page may be written back in the same thread. */
 856                 if (PageDirty(vmpage))
 857                         unplug = true;
 858
 859                 /* We may have one full RPC, commit it soon */
 860                 if (plist->pl_nr >= PTLRPC_MAX_BRW_PAGES)
 861                         unplug = true;
 862
 863                 CL_PAGE_DEBUG(D_VFSTRACE, env, page,
 864                               "queued page: %d.\n", plist->pl_nr);
 865         } else {
 866                 cl_page_disown(env, io, page);
 867
 868                 lcc->lcc_page = NULL;
 869                 lu_ref_del(&page->cp_reference, "cl_io", io);
 870                 cl_page_put(env, page);
 871
 872                 /* page list is not contiguous now, commit it now */
 873                 unplug = true;
 874         }
 875         if (unplug || io->u.ci_wr.wr_sync)
 876                 result = vvp_io_write_commit(env, io);
 877
 878         if (result < 0)
 879                 io->ci_result = result;
 880
 881
 882 out:
 883         RETURN(result >= 0 ? copied : result);
 884 }
 885
 886 #ifdef CONFIG_MIGRATION
 887 static int ll_migratepage(struct address_space *mapping,
 888                           struct page *newpage, struct page *page
 889 #ifdef HAVE_MIGRATEPAGE_4ARGS
 890                           , enum migrate_mode mode
 891 #endif
 892         )
 893 {
 894         /* Always fail page migration until we have a proper implementation */
 895         return -EIO;
 896 }
 897 #endif
 898
 899 const struct address_space_operations ll_aops = {
 900         .readpage       = ll_readpage,
 901         .direct_IO      = ll_direct_IO,
 902         .writepage      = ll_writepage,
 903         .writepages     = ll_writepages,
 904         .set_page_dirty = __set_page_dirty_nobuffers,
 905         .write_begin    = ll_write_begin,
 906         .write_end      = ll_write_end,
 907         .invalidatepage = ll_invalidatepage,
 908         .releasepage    = (void *)ll_releasepage,
 909 #ifdef CONFIG_MIGRATION
 910         .migratepage    = ll_migratepage,
 911 #endif
 912 };