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   1 #include "ceph_debug.h"
   2
   3 #include <linux/backing-dev.h>
   4 #include <linux/fs.h>
   5 #include <linux/mm.h>
   6 #include <linux/pagemap.h>
   7 #include <linux/writeback.h>    /* generic_writepages */
   8 #include <linux/slab.h>
   9 #include <linux/pagevec.h>
  10 #include <linux/task_io_accounting_ops.h>
  11
  12 #include "super.h"
  13 #include "osd_client.h"
  14
  15 /*
  16  * Ceph address space ops.
  17  *
  18  * There are a few funny things going on here.
  19  *
  20  * The page->private field is used to reference a struct
  21  * ceph_snap_context for _every_ dirty page.  This indicates which
  22  * snapshot the page was logically dirtied in, and thus which snap
  23  * context needs to be associated with the osd write during writeback.
  24  *
  25  * Similarly, struct ceph_inode_info maintains a set of counters to
  26  * count dirty pages on the inode.  In the absense of snapshots,
  27  * i_wrbuffer_ref == i_wrbuffer_ref_head == the dirty page count.
  28  *
  29  * When a snapshot is taken (that is, when the client receives
  30  * notification that a snapshot was taken), each inode with caps and
  31  * with dirty pages (dirty pages implies there is a cap) gets a new
  32  * ceph_cap_snap in the i_cap_snaps list (which is sorted in ascending
  33  * order, new snaps go to the tail).  The i_wrbuffer_ref_head count is
  34  * moved to capsnap->dirty. (Unless a sync write is currently in
  35  * progress.  In that case, the capsnap is said to be "pending", new
  36  * writes cannot start, and the capsnap isn't "finalized" until the
  37  * write completes (or fails) and a final size/mtime for the inode for
  38  * that snap can be settled upon.)  i_wrbuffer_ref_head is reset to 0.
  39  *
  40  * On writeback, we must submit writes to the osd IN SNAP ORDER.  So,
  41  * we look for the first capsnap in i_cap_snaps and write out pages in
  42  * that snap context _only_.  Then we move on to the next capsnap,
  43  * eventually reaching the "live" or "head" context (i.e., pages that
  44  * are not yet snapped) and are writing the most recently dirtied
  45  * pages.
  46  *
  47  * Invalidate and so forth must take care to ensure the dirty page
  48  * accounting is preserved.
  49  */
  50
  51 #define CONGESTION_ON_THRESH(congestion_kb) (congestion_kb >> (PAGE_SHIFT-10))
  52 #define CONGESTION_OFF_THRESH(congestion_kb)                            \
  53         (CONGESTION_ON_THRESH(congestion_kb) -                          \
  54          (CONGESTION_ON_THRESH(congestion_kb) >> 2))
  55
  56
  57
  58 /*
  59  * Dirty a page.  Optimistically adjust accounting, on the assumption
  60  * that we won't race with invalidate.  If we do, readjust.
  61  */
  62 static int ceph_set_page_dirty(struct page *page)
  63 {
  64         struct address_space *mapping = page->mapping;
  65         struct inode *inode;
  66         struct ceph_inode_info *ci;
  67         int undo = 0;
  68         struct ceph_snap_context *snapc;
  69
  70         if (unlikely(!mapping))
  71                 return !TestSetPageDirty(page);
  72
  73         if (TestSetPageDirty(page)) {
  74                 dout("%p set_page_dirty %p idx %lu -- already dirty\n",
  75                      mapping->host, page, page->index);
  76                 return 0;
  77         }
  78
  79         inode = mapping->host;
  80         ci = ceph_inode(inode);
  81
  82         /*
  83          * Note that we're grabbing a snapc ref here without holding
  84          * any locks!
  85          */
  86         snapc = ceph_get_snap_context(ci->i_snap_realm->cached_context);
  87
  88         /* dirty the head */
  89         spin_lock(&inode->i_lock);
  90         if (ci->i_wrbuffer_ref_head == 0)
  91                 ci->i_head_snapc = ceph_get_snap_context(snapc);
  92         ++ci->i_wrbuffer_ref_head;
  93         if (ci->i_wrbuffer_ref == 0)
  94                 igrab(inode);
  95         ++ci->i_wrbuffer_ref;
  96         dout("%p set_page_dirty %p idx %lu head %d/%d -> %d/%d "
  97              "snapc %p seq %lld (%d snaps)\n",
  98              mapping->host, page, page->index,
  99              ci->i_wrbuffer_ref-1, ci->i_wrbuffer_ref_head-1,
 100              ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
 101              snapc, snapc->seq, snapc->num_snaps);
 102         spin_unlock(&inode->i_lock);
 103
 104         /* now adjust page */
 105         spin_lock_irq(&mapping->tree_lock);
 106         if (page->mapping) {    /* Race with truncate? */
 107                 WARN_ON_ONCE(!PageUptodate(page));
 108
 109                 if (mapping_cap_account_dirty(mapping)) {
 110                         __inc_zone_page_state(page, NR_FILE_DIRTY);
 111                         __inc_bdi_stat(mapping->backing_dev_info,
 112                                         BDI_RECLAIMABLE);
 113                         task_io_account_write(PAGE_CACHE_SIZE);
 114                 }
 115                 radix_tree_tag_set(&mapping->page_tree,
 116                                 page_index(page), PAGECACHE_TAG_DIRTY);
 117
 118                 /*
 119                  * Reference snap context in page->private.  Also set
 120                  * PagePrivate so that we get invalidatepage callback.
 121                  */
 122                 page->private = (unsigned long)snapc;
 123                 SetPagePrivate(page);
 124         } else {
 125                 dout("ANON set_page_dirty %p (raced truncate?)\n", page);
 126                 undo = 1;
 127         }
 128
 129         spin_unlock_irq(&mapping->tree_lock);
 130
 131         if (undo)
 132                 /* whoops, we failed to dirty the page */
 133                 ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
 134
 135         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
 136
 137         BUG_ON(!PageDirty(page));
 138         return 1;
 139 }
 140
 141 /*
 142  * If we are truncating the full page (i.e. offset == 0), adjust the
 143  * dirty page counters appropriately.  Only called if there is private
 144  * data on the page.
 145  */
 146 static void ceph_invalidatepage(struct page *page, unsigned long offset)
 147 {
 148         struct inode *inode;
 149         struct ceph_inode_info *ci;
 150         struct ceph_snap_context *snapc = (void *)page->private;
 151
 152         BUG_ON(!PageLocked(page));
 153         BUG_ON(!page->private);
 154         BUG_ON(!PagePrivate(page));
 155         BUG_ON(!page->mapping);
 156
 157         inode = page->mapping->host;
 158
 159         /*
 160          * We can get non-dirty pages here due to races between
 161          * set_page_dirty and truncate_complete_page; just spit out a
 162          * warning, in case we end up with accounting problems later.
 163          */
 164         if (!PageDirty(page))
 165                 pr_err("%p invalidatepage %p page not dirty\n", inode, page);
 166
 167         if (offset == 0)
 168                 ClearPageChecked(page);
 169
 170         ci = ceph_inode(inode);
 171         if (offset == 0) {
 172                 dout("%p invalidatepage %p idx %lu full dirty page %lu\n",
 173                      inode, page, page->index, offset);
 174                 ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
 175                 ceph_put_snap_context(snapc);
 176                 page->private = 0;
 177                 ClearPagePrivate(page);
 178         } else {
 179                 dout("%p invalidatepage %p idx %lu partial dirty page\n",
 180                      inode, page, page->index);
 181         }
 182 }
 183
 184 /* just a sanity check */
 185 static int ceph_releasepage(struct page *page, gfp_t g)
 186 {
 187         struct inode *inode = page->mapping ? page->mapping->host : NULL;
 188         dout("%p releasepage %p idx %lu\n", inode, page, page->index);
 189         WARN_ON(PageDirty(page));
 190         WARN_ON(page->private);
 191         WARN_ON(PagePrivate(page));
 192         return 0;
 193 }
 194
 195 /*
 196  * read a single page, without unlocking it.
 197  */
 198 static int readpage_nounlock(struct file *filp, struct page *page)
 199 {
 200         struct inode *inode = filp->f_dentry->d_inode;
 201         struct ceph_inode_info *ci = ceph_inode(inode);
 202         struct ceph_osd_client *osdc = &ceph_inode_to_client(inode)->osdc;
 203         int err = 0;
 204         u64 len = PAGE_CACHE_SIZE;
 205
 206         dout("readpage inode %p file %p page %p index %lu\n",
 207              inode, filp, page, page->index);
 208         err = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
 209                                   page->index << PAGE_CACHE_SHIFT, &len,
 210                                   ci->i_truncate_seq, ci->i_truncate_size,
 211                                   &page, 1);
 212         if (err == -ENOENT)
 213                 err = 0;
 214         if (err < 0) {
 215                 SetPageError(page);
 216                 goto out;
 217         } else if (err < PAGE_CACHE_SIZE) {
 218                 /* zero fill remainder of page */
 219                 zero_user_segment(page, err, PAGE_CACHE_SIZE);
 220         }
 221         SetPageUptodate(page);
 222
 223 out:
 224         return err < 0 ? err : 0;
 225 }
 226
 227 static int ceph_readpage(struct file *filp, struct page *page)
 228 {
 229         int r = readpage_nounlock(filp, page);
 230         unlock_page(page);
 231         return r;
 232 }
 233
 234 /*
 235  * Build a vector of contiguous pages from the provided page list.
 236  */
 237 static struct page **page_vector_from_list(struct list_head *page_list,
 238                                            unsigned *nr_pages)
 239 {
 240         struct page **pages;
 241         struct page *page;
 242         int next_index, contig_pages = 0;
 243
 244         /* build page vector */
 245         pages = kmalloc(sizeof(*pages) * *nr_pages, GFP_NOFS);
 246         if (!pages)
 247                 return ERR_PTR(-ENOMEM);
 248
 249         BUG_ON(list_empty(page_list));
 250         next_index = list_entry(page_list->prev, struct page, lru)->index;
 251         list_for_each_entry_reverse(page, page_list, lru) {
 252                 if (page->index == next_index) {
 253                         dout("readpages page %d %p\n", contig_pages, page);
 254                         pages[contig_pages] = page;
 255                         contig_pages++;
 256                         next_index++;
 257                 } else {
 258                         break;
 259                 }
 260         }
 261         *nr_pages = contig_pages;
 262         return pages;
 263 }
 264
 265 /*
 266  * Read multiple pages.  Leave pages we don't read + unlock in page_list;
 267  * the caller (VM) cleans them up.
 268  */
 269 static int ceph_readpages(struct file *file, struct address_space *mapping,
 270                           struct list_head *page_list, unsigned nr_pages)
 271 {
 272         struct inode *inode = file->f_dentry->d_inode;
 273         struct ceph_inode_info *ci = ceph_inode(inode);
 274         struct ceph_osd_client *osdc = &ceph_inode_to_client(inode)->osdc;
 275         int rc = 0;
 276         struct page **pages;
 277         loff_t offset;
 278         u64 len;
 279
 280         dout("readpages %p file %p nr_pages %d\n",
 281              inode, file, nr_pages);
 282
 283         pages = page_vector_from_list(page_list, &nr_pages);
 284         if (IS_ERR(pages))
 285                 return PTR_ERR(pages);
 286
 287         /* guess read extent */
 288         offset = pages[0]->index << PAGE_CACHE_SHIFT;
 289         len = nr_pages << PAGE_CACHE_SHIFT;
 290         rc = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
 291                                  offset, &len,
 292                                  ci->i_truncate_seq, ci->i_truncate_size,
 293                                  pages, nr_pages);
 294         if (rc == -ENOENT)
 295                 rc = 0;
 296         if (rc < 0)
 297                 goto out;
 298
 299         for (; !list_empty(page_list) && len > 0;
 300              rc -= PAGE_CACHE_SIZE, len -= PAGE_CACHE_SIZE) {
 301                 struct page *page =
 302                         list_entry(page_list->prev, struct page, lru);
 303
 304                 list_del(&page->lru);
 305
 306                 if (rc < (int)PAGE_CACHE_SIZE) {
 307                         /* zero (remainder of) page */
 308                         int s = rc < 0 ? 0 : rc;
 309                         zero_user_segment(page, s, PAGE_CACHE_SIZE);
 310                 }
 311
 312                 if (add_to_page_cache_lru(page, mapping, page->index, GFP_NOFS)) {
 313                         page_cache_release(page);
 314                         dout("readpages %p add_to_page_cache failed %p\n",
 315                              inode, page);
 316                         continue;
 317                 }
 318                 dout("readpages %p adding %p idx %lu\n", inode, page,
 319                      page->index);
 320                 flush_dcache_page(page);
 321                 SetPageUptodate(page);
 322                 unlock_page(page);
 323                 page_cache_release(page);
 324         }
 325         rc = 0;
 326
 327 out:
 328         kfree(pages);
 329         return rc;
 330 }
 331
 332 /*
 333  * Get ref for the oldest snapc for an inode with dirty data... that is, the
 334  * only snap context we are allowed to write back.
 335  */
 336 static struct ceph_snap_context *get_oldest_context(struct inode *inode,
 337                                                     u64 *snap_size)
 338 {
 339         struct ceph_inode_info *ci = ceph_inode(inode);
 340         struct ceph_snap_context *snapc = NULL;
 341         struct ceph_cap_snap *capsnap = NULL;
 342
 343         spin_lock(&inode->i_lock);
 344         list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
 345                 dout(" cap_snap %p snapc %p has %d dirty pages\n", capsnap,
 346                      capsnap->context, capsnap->dirty_pages);
 347                 if (capsnap->dirty_pages) {
 348                         snapc = ceph_get_snap_context(capsnap->context);
 349                         if (snap_size)
 350                                 *snap_size = capsnap->size;
 351                         break;
 352                 }
 353         }
 354         if (!snapc && ci->i_head_snapc) {
 355                 snapc = ceph_get_snap_context(ci->i_head_snapc);
 356                 dout(" head snapc %p has %d dirty pages\n",
 357                      snapc, ci->i_wrbuffer_ref_head);
 358         }
 359         spin_unlock(&inode->i_lock);
 360         return snapc;
 361 }
 362
 363 /*
 364  * Write a single page, but leave the page locked.
 365  *
 366  * If we get a write error, set the page error bit, but still adjust the
 367  * dirty page accounting (i.e., page is no longer dirty).
 368  */
 369 static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
 370 {
 371         struct inode *inode;
 372         struct ceph_inode_info *ci;
 373         struct ceph_client *client;
 374         struct ceph_osd_client *osdc;
 375         loff_t page_off = page->index << PAGE_CACHE_SHIFT;
 376         int len = PAGE_CACHE_SIZE;
 377         loff_t i_size;
 378         int err = 0;
 379         struct ceph_snap_context *snapc, *oldest;
 380         u64 snap_size = 0;
 381         long writeback_stat;
 382
 383         dout("writepage %p idx %lu\n", page, page->index);
 384
 385         if (!page->mapping || !page->mapping->host) {
 386                 dout("writepage %p - no mapping\n", page);
 387                 return -EFAULT;
 388         }
 389         inode = page->mapping->host;
 390         ci = ceph_inode(inode);
 391         client = ceph_inode_to_client(inode);
 392         osdc = &client->osdc;
 393
 394         /* verify this is a writeable snap context */
 395         snapc = (void *)page->private;
 396         if (snapc == NULL) {
 397                 dout("writepage %p page %p not dirty?\n", inode, page);
 398                 goto out;
 399         }
 400         oldest = get_oldest_context(inode, &snap_size);
 401         if (snapc->seq > oldest->seq) {
 402                 dout("writepage %p page %p snapc %p not writeable - noop\n",
 403                      inode, page, (void *)page->private);
 404                 /* we should only noop if called by kswapd */
 405                 WARN_ON((current->flags & PF_MEMALLOC) == 0);
 406                 ceph_put_snap_context(oldest);
 407                 goto out;
 408         }
 409         ceph_put_snap_context(oldest);
 410
 411         /* is this a partial page at end of file? */
 412         if (snap_size)
 413                 i_size = snap_size;
 414         else
 415                 i_size = i_size_read(inode);
 416         if (i_size < page_off + len)
 417                 len = i_size - page_off;
 418
 419         dout("writepage %p page %p index %lu on %llu~%u\n",
 420              inode, page, page->index, page_off, len);
 421
 422         writeback_stat = atomic_long_inc_return(&client->writeback_count);
 423         if (writeback_stat >
 424             CONGESTION_ON_THRESH(client->mount_args->congestion_kb))
 425                 set_bdi_congested(&client->backing_dev_info, BLK_RW_ASYNC);
 426
 427         set_page_writeback(page);
 428         err = ceph_osdc_writepages(osdc, ceph_vino(inode),
 429                                    &ci->i_layout, snapc,
 430                                    page_off, len,
 431                                    ci->i_truncate_seq, ci->i_truncate_size,
 432                                    &inode->i_mtime,
 433                                    &page, 1, 0, 0, true);
 434         if (err < 0) {
 435                 dout("writepage setting page/mapping error %d %p\n", err, page);
 436                 SetPageError(page);
 437                 mapping_set_error(&inode->i_data, err);
 438                 if (wbc)
 439                         wbc->pages_skipped++;
 440         } else {
 441                 dout("writepage cleaned page %p\n", page);
 442                 err = 0;  /* vfs expects us to return 0 */
 443         }
 444         page->private = 0;
 445         ClearPagePrivate(page);
 446         end_page_writeback(page);
 447         ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
 448         ceph_put_snap_context(snapc);  /* page's reference */
 449 out:
 450         return err;
 451 }
 452
 453 static int ceph_writepage(struct page *page, struct writeback_control *wbc)
 454 {
 455         int err;
 456         struct inode *inode = page->mapping->host;
 457         BUG_ON(!inode);
 458         igrab(inode);
 459         err = writepage_nounlock(page, wbc);
 460         unlock_page(page);
 461         iput(inode);
 462         return err;
 463 }
 464
 465
 466 /*
 467  * lame release_pages helper.  release_pages() isn't exported to
 468  * modules.
 469  */
 470 static void ceph_release_pages(struct page **pages, int num)
 471 {
 472         struct pagevec pvec;
 473         int i;
 474
 475         pagevec_init(&pvec, 0);
 476         for (i = 0; i < num; i++) {
 477                 if (pagevec_add(&pvec, pages[i]) == 0)
 478                         pagevec_release(&pvec);
 479         }
 480         pagevec_release(&pvec);
 481 }
 482
 483
 484 /*
 485  * async writeback completion handler.
 486  *
 487  * If we get an error, set the mapping error bit, but not the individual
 488  * page error bits.
 489  */
 490 static void writepages_finish(struct ceph_osd_request *req,
 491                               struct ceph_msg *msg)
 492 {
 493         struct inode *inode = req->r_inode;
 494         struct ceph_osd_reply_head *replyhead;
 495         struct ceph_osd_op *op;
 496         struct ceph_inode_info *ci = ceph_inode(inode);
 497         unsigned wrote;
 498         struct page *page;
 499         int i;
 500         struct ceph_snap_context *snapc = req->r_snapc;
 501         struct address_space *mapping = inode->i_mapping;
 502         __s32 rc = -EIO;
 503         u64 bytes = 0;
 504         struct ceph_client *client = ceph_inode_to_client(inode);
 505         long writeback_stat;
 506         unsigned issued = ceph_caps_issued(ci);
 507
 508         /* parse reply */
 509         replyhead = msg->front.iov_base;
 510         WARN_ON(le32_to_cpu(replyhead->num_ops) == 0);
 511         op = (void *)(replyhead + 1);
 512         rc = le32_to_cpu(replyhead->result);
 513         bytes = le64_to_cpu(op->extent.length);
 514
 515         if (rc >= 0) {
 516                 /*
 517                  * Assume we wrote the pages we originally sent.  The
 518                  * osd might reply with fewer pages if our writeback
 519                  * raced with a truncation and was adjusted at the osd,
 520                  * so don't believe the reply.
 521                  */
 522                 wrote = req->r_num_pages;
 523         } else {
 524                 wrote = 0;
 525                 mapping_set_error(mapping, rc);
 526         }
 527         dout("writepages_finish %p rc %d bytes %llu wrote %d (pages)\n",
 528              inode, rc, bytes, wrote);
 529
 530         /* clean all pages */
 531         for (i = 0; i < req->r_num_pages; i++) {
 532                 page = req->r_pages[i];
 533                 BUG_ON(!page);
 534                 WARN_ON(!PageUptodate(page));
 535
 536                 writeback_stat =
 537                         atomic_long_dec_return(&client->writeback_count);
 538                 if (writeback_stat <
 539                     CONGESTION_OFF_THRESH(client->mount_args->congestion_kb))
 540                         clear_bdi_congested(&client->backing_dev_info,
 541                                             BLK_RW_ASYNC);
 542
 543                 ceph_put_snap_context((void *)page->private);
 544                 page->private = 0;
 545                 ClearPagePrivate(page);
 546                 dout("unlocking %d %p\n", i, page);
 547                 end_page_writeback(page);
 548
 549                 /*
 550                  * We lost the cache cap, need to truncate the page before
 551                  * it is unlocked, otherwise we'd truncate it later in the
 552                  * page truncation thread, possibly losing some data that
 553                  * raced its way in
 554                  */
 555                 if ((issued & CEPH_CAP_FILE_CACHE) == 0)
 556                         generic_error_remove_page(inode->i_mapping, page);
 557
 558                 unlock_page(page);
 559         }
 560         dout("%p wrote+cleaned %d pages\n", inode, wrote);
 561         ceph_put_wrbuffer_cap_refs(ci, req->r_num_pages, snapc);
 562
 563         ceph_release_pages(req->r_pages, req->r_num_pages);
 564         if (req->r_pages_from_pool)
 565                 mempool_free(req->r_pages,
 566                              ceph_sb_to_client(inode->i_sb)->wb_pagevec_pool);
 567         else
 568                 kfree(req->r_pages);
 569         ceph_osdc_put_request(req);
 570 }
 571
 572 /*
 573  * allocate a page vec, either directly, or if necessary, via a the
 574  * mempool.  we avoid the mempool if we can because req->r_num_pages
 575  * may be less than the maximum write size.
 576  */
 577 static void alloc_page_vec(struct ceph_client *client,
 578                            struct ceph_osd_request *req)
 579 {
 580         req->r_pages = kmalloc(sizeof(struct page *) * req->r_num_pages,
 581                                GFP_NOFS);
 582         if (!req->r_pages) {
 583                 req->r_pages = mempool_alloc(client->wb_pagevec_pool, GFP_NOFS);
 584                 req->r_pages_from_pool = 1;
 585                 WARN_ON(!req->r_pages);
 586         }
 587 }
 588
 589 /*
 590  * initiate async writeback
 591  */
 592 static int ceph_writepages_start(struct address_space *mapping,
 593                                  struct writeback_control *wbc)
 594 {
 595         struct inode *inode = mapping->host;
 596         struct backing_dev_info *bdi = mapping->backing_dev_info;
 597         struct ceph_inode_info *ci = ceph_inode(inode);
 598         struct ceph_client *client;
 599         pgoff_t index, start, end;
 600         int range_whole = 0;
 601         int should_loop = 1;
 602         pgoff_t max_pages = 0, max_pages_ever = 0;
 603         struct ceph_snap_context *snapc = NULL, *last_snapc = NULL, *pgsnapc;
 604         struct pagevec pvec;
 605         int done = 0;
 606         int rc = 0;
 607         unsigned wsize = 1 << inode->i_blkbits;
 608         struct ceph_osd_request *req = NULL;
 609         int do_sync;
 610         u64 snap_size = 0;
 611
 612         /*
 613          * Include a 'sync' in the OSD request if this is a data
 614          * integrity write (e.g., O_SYNC write or fsync()), or if our
 615          * cap is being revoked.
 616          */
 617         do_sync = wbc->sync_mode == WB_SYNC_ALL;
 618         if (ceph_caps_revoking(ci, CEPH_CAP_FILE_BUFFER))
 619                 do_sync = 1;
 620         dout("writepages_start %p dosync=%d (mode=%s)\n",
 621              inode, do_sync,
 622              wbc->sync_mode == WB_SYNC_NONE ? "NONE" :
 623              (wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD"));
 624
 625         client = ceph_inode_to_client(inode);
 626         if (client->mount_state == CEPH_MOUNT_SHUTDOWN) {
 627                 pr_warning("writepage_start %p on forced umount\n", inode);
 628                 return -EIO; /* we're in a forced umount, don't write! */
 629         }
 630         if (client->mount_args->wsize && client->mount_args->wsize < wsize)
 631                 wsize = client->mount_args->wsize;
 632         if (wsize < PAGE_CACHE_SIZE)
 633                 wsize = PAGE_CACHE_SIZE;
 634         max_pages_ever = wsize >> PAGE_CACHE_SHIFT;
 635
 636         pagevec_init(&pvec, 0);
 637
 638         /* ?? */
 639         if (wbc->nonblocking && bdi_write_congested(bdi)) {
 640                 dout(" writepages congested\n");
 641                 wbc->encountered_congestion = 1;
 642                 goto out_final;
 643         }
 644
 645         /* where to start/end? */
 646         if (wbc->range_cyclic) {
 647                 start = mapping->writeback_index; /* Start from prev offset */
 648                 end = -1;
 649                 dout(" cyclic, start at %lu\n", start);
 650         } else {
 651                 start = wbc->range_start >> PAGE_CACHE_SHIFT;
 652                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
 653                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 654                         range_whole = 1;
 655                 should_loop = 0;
 656                 dout(" not cyclic, %lu to %lu\n", start, end);
 657         }
 658         index = start;
 659
 660 retry:
 661         /* find oldest snap context with dirty data */
 662         ceph_put_snap_context(snapc);
 663         snapc = get_oldest_context(inode, &snap_size);
 664         if (!snapc) {
 665                 /* hmm, why does writepages get called when there
 666                    is no dirty data? */
 667                 dout(" no snap context with dirty data?\n");
 668                 goto out;
 669         }
 670         dout(" oldest snapc is %p seq %lld (%d snaps)\n",
 671              snapc, snapc->seq, snapc->num_snaps);
 672         if (last_snapc && snapc != last_snapc) {
 673                 /* if we switched to a newer snapc, restart our scan at the
 674                  * start of the original file range. */
 675                 dout("  snapc differs from last pass, restarting at %lu\n",
 676                      index);
 677                 index = start;
 678         }
 679         last_snapc = snapc;
 680
 681         while (!done && index <= end) {
 682                 unsigned i;
 683                 int first;
 684                 pgoff_t next;
 685                 int pvec_pages, locked_pages;
 686                 struct page *page;
 687                 int want;
 688                 u64 offset, len;
 689                 struct ceph_osd_request_head *reqhead;
 690                 struct ceph_osd_op *op;
 691                 long writeback_stat;
 692
 693                 next = 0;
 694                 locked_pages = 0;
 695                 max_pages = max_pages_ever;
 696
 697 get_more_pages:
 698                 first = -1;
 699                 want = min(end - index,
 700                            min((pgoff_t)PAGEVEC_SIZE,
 701                                max_pages - (pgoff_t)locked_pages) - 1)
 702                         + 1;
 703                 pvec_pages = pagevec_lookup_tag(&pvec, mapping, &index,
 704                                                 PAGECACHE_TAG_DIRTY,
 705                                                 want);
 706                 dout("pagevec_lookup_tag got %d\n", pvec_pages);
 707                 if (!pvec_pages && !locked_pages)
 708                         break;
 709                 for (i = 0; i < pvec_pages && locked_pages < max_pages; i++) {
 710                         page = pvec.pages[i];
 711                         dout("? %p idx %lu\n", page, page->index);
 712                         if (locked_pages == 0)
 713                                 lock_page(page);  /* first page */
 714                         else if (!trylock_page(page))
 715                                 break;
 716
 717                         /* only dirty pages, or our accounting breaks */
 718                         if (unlikely(!PageDirty(page)) ||
 719                             unlikely(page->mapping != mapping)) {
 720                                 dout("!dirty or !mapping %p\n", page);
 721                                 unlock_page(page);
 722                                 break;
 723                         }
 724                         if (!wbc->range_cyclic && page->index > end) {
 725                                 dout("end of range %p\n", page);
 726                                 done = 1;
 727                                 unlock_page(page);
 728                                 break;
 729                         }
 730                         if (next && (page->index != next)) {
 731                                 dout("not consecutive %p\n", page);
 732                                 unlock_page(page);
 733                                 break;
 734                         }
 735                         if (wbc->sync_mode != WB_SYNC_NONE) {
 736                                 dout("waiting on writeback %p\n", page);
 737                                 wait_on_page_writeback(page);
 738                         }
 739                         if ((snap_size && page_offset(page) > snap_size) ||
 740                             (!snap_size &&
 741                              page_offset(page) > i_size_read(inode))) {
 742                                 dout("%p page eof %llu\n", page, snap_size ?
 743                                      snap_size : i_size_read(inode));
 744                                 done = 1;
 745                                 unlock_page(page);
 746                                 break;
 747                         }
 748                         if (PageWriteback(page)) {
 749                                 dout("%p under writeback\n", page);
 750                                 unlock_page(page);
 751                                 break;
 752                         }
 753
 754                         /* only if matching snap context */
 755                         pgsnapc = (void *)page->private;
 756                         if (pgsnapc->seq > snapc->seq) {
 757                                 dout("page snapc %p %lld > oldest %p %lld\n",
 758                                      pgsnapc, pgsnapc->seq, snapc, snapc->seq);
 759                                 unlock_page(page);
 760                                 if (!locked_pages)
 761                                         continue; /* keep looking for snap */
 762                                 break;
 763                         }
 764
 765                         if (!clear_page_dirty_for_io(page)) {
 766                                 dout("%p !clear_page_dirty_for_io\n", page);
 767                                 unlock_page(page);
 768                                 break;
 769                         }
 770
 771                         /* ok */
 772                         if (locked_pages == 0) {
 773                                 /* prepare async write request */
 774                                 offset = page->index << PAGE_CACHE_SHIFT;
 775                                 len = wsize;
 776                                 req = ceph_osdc_new_request(&client->osdc,
 777                                             &ci->i_layout,
 778                                             ceph_vino(inode),
 779                                             offset, &len,
 780                                             CEPH_OSD_OP_WRITE,
 781                                             CEPH_OSD_FLAG_WRITE |
 782                                                     CEPH_OSD_FLAG_ONDISK,
 783                                             snapc, do_sync,
 784                                             ci->i_truncate_seq,
 785                                             ci->i_truncate_size,
 786                                             &inode->i_mtime, true, 1);
 787                                 max_pages = req->r_num_pages;
 788
 789                                 alloc_page_vec(client, req);
 790                                 req->r_callback = writepages_finish;
 791                                 req->r_inode = inode;
 792                         }
 793
 794                         /* note position of first page in pvec */
 795                         if (first < 0)
 796                                 first = i;
 797                         dout("%p will write page %p idx %lu\n",
 798                              inode, page, page->index);
 799
 800                         writeback_stat = atomic_long_inc_return(&client->writeback_count);
 801                         if (writeback_stat > CONGESTION_ON_THRESH(client->mount_args->congestion_kb)) {
 802                                 set_bdi_congested(&client->backing_dev_info, BLK_RW_ASYNC);
 803                         }
 804
 805                         set_page_writeback(page);
 806                         req->r_pages[locked_pages] = page;
 807                         locked_pages++;
 808                         next = page->index + 1;
 809                 }
 810
 811                 /* did we get anything? */
 812                 if (!locked_pages)
 813                         goto release_pvec_pages;
 814                 if (i) {
 815                         int j;
 816                         BUG_ON(!locked_pages || first < 0);
 817
 818                         if (pvec_pages && i == pvec_pages &&
 819                             locked_pages < max_pages) {
 820                                 dout("reached end pvec, trying for more\n");
 821                                 pagevec_reinit(&pvec);
 822                                 goto get_more_pages;
 823                         }
 824
 825                         /* shift unused pages over in the pvec...  we
 826                          * will need to release them below. */
 827                         for (j = i; j < pvec_pages; j++) {
 828                                 dout(" pvec leftover page %p\n",
 829                                      pvec.pages[j]);
 830                                 pvec.pages[j-i+first] = pvec.pages[j];
 831                         }
 832                         pvec.nr -= i-first;
 833                 }
 834
 835                 /* submit the write */
 836                 offset = req->r_pages[0]->index << PAGE_CACHE_SHIFT;
 837                 len = min((snap_size ? snap_size : i_size_read(inode)) - offset,
 838                           (u64)locked_pages << PAGE_CACHE_SHIFT);
 839                 dout("writepages got %d pages at %llu~%llu\n",
 840                      locked_pages, offset, len);
 841
 842                 /* revise final length, page count */
 843                 req->r_num_pages = locked_pages;
 844                 reqhead = req->r_request->front.iov_base;
 845                 op = (void *)(reqhead + 1);
 846                 op->extent.length = cpu_to_le64(len);
 847                 op->payload_len = cpu_to_le32(len);
 848                 req->r_request->hdr.data_len = cpu_to_le32(len);
 849
 850                 ceph_osdc_start_request(&client->osdc, req, true);
 851                 req = NULL;
 852
 853                 /* continue? */
 854                 index = next;
 855                 wbc->nr_to_write -= locked_pages;
 856                 if (wbc->nr_to_write <= 0)
 857                         done = 1;
 858
 859 release_pvec_pages:
 860                 dout("pagevec_release on %d pages (%p)\n", (int)pvec.nr,
 861                      pvec.nr ? pvec.pages[0] : NULL);
 862                 pagevec_release(&pvec);
 863
 864                 if (locked_pages && !done)
 865                         goto retry;
 866         }
 867
 868         if (should_loop && !done) {
 869                 /* more to do; loop back to beginning of file */
 870                 dout("writepages looping back to beginning of file\n");
 871                 should_loop = 0;
 872                 index = 0;
 873                 goto retry;
 874         }
 875
 876         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 877                 mapping->writeback_index = index;
 878
 879 out:
 880         if (req)
 881                 ceph_osdc_put_request(req);
 882         if (rc > 0)
 883                 rc = 0;  /* vfs expects us to return 0 */
 884         ceph_put_snap_context(snapc);
 885         dout("writepages done, rc = %d\n", rc);
 886 out_final:
 887         return rc;
 888 }
 889
 890
 891
 892 /*
 893  * See if a given @snapc is either writeable, or already written.
 894  */
 895 static int context_is_writeable_or_written(struct inode *inode,
 896                                            struct ceph_snap_context *snapc)
 897 {
 898         struct ceph_snap_context *oldest = get_oldest_context(inode, NULL);
 899         int ret = !oldest || snapc->seq <= oldest->seq;
 900
 901         ceph_put_snap_context(oldest);
 902         return ret;
 903 }
 904
 905 /*
 906  * We are only allowed to write into/dirty the page if the page is
 907  * clean, or already dirty within the same snap context.
 908  *
 909  * called with page locked.
 910  * return success with page locked,
 911  * or any failure (incl -EAGAIN) with page unlocked.
 912  */
 913 static int ceph_update_writeable_page(struct file *file,
 914                             loff_t pos, unsigned len,
 915                             struct page *page)
 916 {
 917         struct inode *inode = file->f_dentry->d_inode;
 918         struct ceph_inode_info *ci = ceph_inode(inode);
 919         struct ceph_mds_client *mdsc = &ceph_inode_to_client(inode)->mdsc;
 920         loff_t page_off = pos & PAGE_CACHE_MASK;
 921         int pos_in_page = pos & ~PAGE_CACHE_MASK;
 922         int end_in_page = pos_in_page + len;
 923         loff_t i_size;
 924         int r;
 925         struct ceph_snap_context *snapc, *oldest;
 926
 927 retry_locked:
 928         /* writepages currently holds page lock, but if we change that later, */
 929         wait_on_page_writeback(page);
 930
 931         /* check snap context */
 932         BUG_ON(!ci->i_snap_realm);
 933         down_read(&mdsc->snap_rwsem);
 934         BUG_ON(!ci->i_snap_realm->cached_context);
 935         snapc = (void *)page->private;
 936         if (snapc && snapc != ci->i_head_snapc) {
 937                 /*
 938                  * this page is already dirty in another (older) snap
 939                  * context!  is it writeable now?
 940                  */
 941                 oldest = get_oldest_context(inode, NULL);
 942                 up_read(&mdsc->snap_rwsem);
 943
 944                 if (snapc->seq > oldest->seq) {
 945                         ceph_put_snap_context(oldest);
 946                         dout(" page %p snapc %p not current or oldest\n",
 947                              page, snapc);
 948                         /*
 949                          * queue for writeback, and wait for snapc to
 950                          * be writeable or written
 951                          */
 952                         snapc = ceph_get_snap_context(snapc);
 953                         unlock_page(page);
 954                         ceph_queue_writeback(inode);
 955                         r = wait_event_interruptible(ci->i_cap_wq,
 956                                context_is_writeable_or_written(inode, snapc));
 957                         ceph_put_snap_context(snapc);
 958                         if (r == -ERESTARTSYS)
 959                                 return r;
 960                         return -EAGAIN;
 961                 }
 962                 ceph_put_snap_context(oldest);
 963
 964                 /* yay, writeable, do it now (without dropping page lock) */
 965                 dout(" page %p snapc %p not current, but oldest\n",
 966                      page, snapc);
 967                 if (!clear_page_dirty_for_io(page))
 968                         goto retry_locked;
 969                 r = writepage_nounlock(page, NULL);
 970                 if (r < 0)
 971                         goto fail_nosnap;
 972                 goto retry_locked;
 973         }
 974
 975         if (PageUptodate(page)) {
 976                 dout(" page %p already uptodate\n", page);
 977                 return 0;
 978         }
 979
 980         /* full page? */
 981         if (pos_in_page == 0 && len == PAGE_CACHE_SIZE)
 982                 return 0;
 983
 984         /* past end of file? */
 985         i_size = inode->i_size;   /* caller holds i_mutex */
 986
 987         if (i_size + len > inode->i_sb->s_maxbytes) {
 988                 /* file is too big */
 989                 r = -EINVAL;
 990                 goto fail;
 991         }
 992
 993         if (page_off >= i_size ||
 994             (pos_in_page == 0 && (pos+len) >= i_size &&
 995              end_in_page - pos_in_page != PAGE_CACHE_SIZE)) {
 996                 dout(" zeroing %p 0 - %d and %d - %d\n",
 997                      page, pos_in_page, end_in_page, (int)PAGE_CACHE_SIZE);
 998                 zero_user_segments(page,
 999                                    0, pos_in_page,
1000                                    end_in_page, PAGE_CACHE_SIZE);
1001                 return 0;
1002         }
1003
1004         /* we need to read it. */
1005         up_read(&mdsc->snap_rwsem);
1006         r = readpage_nounlock(file, page);
1007         if (r < 0)
1008                 goto fail_nosnap;
1009         goto retry_locked;
1010
1011 fail:
1012         up_read(&mdsc->snap_rwsem);
1013 fail_nosnap:
1014         unlock_page(page);
1015         return r;
1016 }
1017
1018 /*
1019  * We are only allowed to write into/dirty the page if the page is
1020  * clean, or already dirty within the same snap context.
1021  */
1022 static int ceph_write_begin(struct file *file, struct address_space *mapping,
1023                             loff_t pos, unsigned len, unsigned flags,
1024                             struct page **pagep, void **fsdata)
1025 {
1026         struct inode *inode = file->f_dentry->d_inode;
1027         struct page *page;
1028         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1029         int r;
1030
1031         do {
1032                 /* get a page */
1033                 page = grab_cache_page_write_begin(mapping, index, 0);
1034                 if (!page)
1035                         return -ENOMEM;
1036                 *pagep = page;
1037
1038                 dout("write_begin file %p inode %p page %p %d~%d\n", file,
1039                 inode, page, (int)pos, (int)len);
1040
1041                 r = ceph_update_writeable_page(file, pos, len, page);
1042         } while (r == -EAGAIN);
1043
1044         return r;
1045 }
1046
1047 /*
1048  * we don't do anything in here that simple_write_end doesn't do
1049  * except adjust dirty page accounting and drop read lock on
1050  * mdsc->snap_rwsem.
1051  */
1052 static int ceph_write_end(struct file *file, struct address_space *mapping,
1053                           loff_t pos, unsigned len, unsigned copied,
1054                           struct page *page, void *fsdata)
1055 {
1056         struct inode *inode = file->f_dentry->d_inode;
1057         struct ceph_client *client = ceph_inode_to_client(inode);
1058         struct ceph_mds_client *mdsc = &client->mdsc;
1059         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1060         int check_cap = 0;
1061
1062         dout("write_end file %p inode %p page %p %d~%d (%d)\n", file,
1063              inode, page, (int)pos, (int)copied, (int)len);
1064
1065         /* zero the stale part of the page if we did a short copy */
1066         if (copied < len)
1067                 zero_user_segment(page, from+copied, len);
1068
1069         /* did file size increase? */
1070         /* (no need for i_size_read(); we caller holds i_mutex */
1071         if (pos+copied > inode->i_size)
1072                 check_cap = ceph_inode_set_size(inode, pos+copied);
1073
1074         if (!PageUptodate(page))
1075                 SetPageUptodate(page);
1076
1077         set_page_dirty(page);
1078
1079         unlock_page(page);
1080         up_read(&mdsc->snap_rwsem);
1081         page_cache_release(page);
1082
1083         if (check_cap)
1084                 ceph_check_caps(ceph_inode(inode), CHECK_CAPS_AUTHONLY, NULL);
1085
1086         return copied;
1087 }
1088
1089 /*
1090  * we set .direct_IO to indicate direct io is supported, but since we
1091  * intercept O_DIRECT reads and writes early, this function should
1092  * never get called.
1093  */
1094 static ssize_t ceph_direct_io(int rw, struct kiocb *iocb,
1095                               const struct iovec *iov,
1096                               loff_t pos, unsigned long nr_segs)
1097 {
1098         WARN_ON(1);
1099         return -EINVAL;
1100 }
1101
1102 const struct address_space_operations ceph_aops = {
1103         .readpage = ceph_readpage,
1104         .readpages = ceph_readpages,
1105         .writepage = ceph_writepage,
1106         .writepages = ceph_writepages_start,
1107         .write_begin = ceph_write_begin,
1108         .write_end = ceph_write_end,
1109         .set_page_dirty = ceph_set_page_dirty,
1110         .invalidatepage = ceph_invalidatepage,
1111         .releasepage = ceph_releasepage,
1112         .direct_IO = ceph_direct_io,
1113 };
1114
1115
1116 /*
1117  * vm ops
1118  */
1119
1120 /*
1121  * Reuse write_begin here for simplicity.
1122  */
1123 static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
1124 {
1125         struct inode *inode = vma->vm_file->f_dentry->d_inode;
1126         struct page *page = vmf->page;
1127         struct ceph_mds_client *mdsc = &ceph_inode_to_client(inode)->mdsc;
1128         loff_t off = page->index << PAGE_CACHE_SHIFT;
1129         loff_t size, len;
1130         int ret;
1131
1132         size = i_size_read(inode);
1133         if (off + PAGE_CACHE_SIZE <= size)
1134                 len = PAGE_CACHE_SIZE;
1135         else
1136                 len = size & ~PAGE_CACHE_MASK;
1137
1138         dout("page_mkwrite %p %llu~%llu page %p idx %lu\n", inode,
1139              off, len, page, page->index);
1140
1141         lock_page(page);
1142
1143         ret = VM_FAULT_NOPAGE;
1144         if ((off > size) ||
1145             (page->mapping != inode->i_mapping))
1146                 goto out;
1147
1148         ret = ceph_update_writeable_page(vma->vm_file, off, len, page);
1149         if (ret == 0) {
1150                 /* success.  we'll keep the page locked. */
1151                 set_page_dirty(page);
1152                 up_read(&mdsc->snap_rwsem);
1153                 ret = VM_FAULT_LOCKED;
1154         } else {
1155                 if (ret == -ENOMEM)
1156                         ret = VM_FAULT_OOM;
1157                 else
1158                         ret = VM_FAULT_SIGBUS;
1159         }
1160 out:
1161         dout("page_mkwrite %p %llu~%llu = %d\n", inode, off, len, ret);
1162         if (ret != VM_FAULT_LOCKED)
1163                 unlock_page(page);
1164         return ret;
1165 }
1166
1167 static struct vm_operations_struct ceph_vmops = {
1168         .fault          = filemap_fault,
1169         .page_mkwrite   = ceph_page_mkwrite,
1170 };
1171
1172 int ceph_mmap(struct file *file, struct vm_area_struct *vma)
1173 {
1174         struct address_space *mapping = file->f_mapping;
1175
1176         if (!mapping->a_ops->readpage)
1177                 return -ENOEXEC;
1178         file_accessed(file);
1179         vma->vm_ops = &ceph_vmops;
1180         vma->vm_flags |= VM_CAN_NONLINEAR;
1181         return 0;
1182 }