Pileus Git - ~andy/linux/blob - fs/ceph/addr.c

   1 #include <linux/ceph/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 "mds_client.h"
  14 #include "cache.h"
  15 #include <linux/ceph/osd_client.h>
  16
  17 /*
  18  * Ceph address space ops.
  19  *
  20  * There are a few funny things going on here.
  21  *
  22  * The page->private field is used to reference a struct
  23  * ceph_snap_context for _every_ dirty page.  This indicates which
  24  * snapshot the page was logically dirtied in, and thus which snap
  25  * context needs to be associated with the osd write during writeback.
  26  *
  27  * Similarly, struct ceph_inode_info maintains a set of counters to
  28  * count dirty pages on the inode.  In the absence of snapshots,
  29  * i_wrbuffer_ref == i_wrbuffer_ref_head == the dirty page count.
  30  *
  31  * When a snapshot is taken (that is, when the client receives
  32  * notification that a snapshot was taken), each inode with caps and
  33  * with dirty pages (dirty pages implies there is a cap) gets a new
  34  * ceph_cap_snap in the i_cap_snaps list (which is sorted in ascending
  35  * order, new snaps go to the tail).  The i_wrbuffer_ref_head count is
  36  * moved to capsnap->dirty. (Unless a sync write is currently in
  37  * progress.  In that case, the capsnap is said to be "pending", new
  38  * writes cannot start, and the capsnap isn't "finalized" until the
  39  * write completes (or fails) and a final size/mtime for the inode for
  40  * that snap can be settled upon.)  i_wrbuffer_ref_head is reset to 0.
  41  *
  42  * On writeback, we must submit writes to the osd IN SNAP ORDER.  So,
  43  * we look for the first capsnap in i_cap_snaps and write out pages in
  44  * that snap context _only_.  Then we move on to the next capsnap,
  45  * eventually reaching the "live" or "head" context (i.e., pages that
  46  * are not yet snapped) and are writing the most recently dirtied
  47  * pages.
  48  *
  49  * Invalidate and so forth must take care to ensure the dirty page
  50  * accounting is preserved.
  51  */
  52
  53 #define CONGESTION_ON_THRESH(congestion_kb) (congestion_kb >> (PAGE_SHIFT-10))
  54 #define CONGESTION_OFF_THRESH(congestion_kb)                            \
  55         (CONGESTION_ON_THRESH(congestion_kb) -                          \
  56          (CONGESTION_ON_THRESH(congestion_kb) >> 2))
  57
  58 static inline struct ceph_snap_context *page_snap_context(struct page *page)
  59 {
  60         if (PagePrivate(page))
  61                 return (void *)page->private;
  62         return NULL;
  63 }
  64
  65 /*
  66  * Dirty a page.  Optimistically adjust accounting, on the assumption
  67  * that we won't race with invalidate.  If we do, readjust.
  68  */
  69 static int ceph_set_page_dirty(struct page *page)
  70 {
  71         struct address_space *mapping = page->mapping;
  72         struct inode *inode;
  73         struct ceph_inode_info *ci;
  74         struct ceph_snap_context *snapc;
  75         int ret;
  76
  77         if (unlikely(!mapping))
  78                 return !TestSetPageDirty(page);
  79
  80         if (PageDirty(page)) {
  81                 dout("%p set_page_dirty %p idx %lu -- already dirty\n",
  82                      mapping->host, page, page->index);
  83                 BUG_ON(!PagePrivate(page));
  84                 return 0;
  85         }
  86
  87         inode = mapping->host;
  88         ci = ceph_inode(inode);
  89
  90         /*
  91          * Note that we're grabbing a snapc ref here without holding
  92          * any locks!
  93          */
  94         snapc = ceph_get_snap_context(ci->i_snap_realm->cached_context);
  95
  96         /* dirty the head */
  97         spin_lock(&ci->i_ceph_lock);
  98         if (ci->i_head_snapc == NULL)
  99                 ci->i_head_snapc = ceph_get_snap_context(snapc);
 100         ++ci->i_wrbuffer_ref_head;
 101         if (ci->i_wrbuffer_ref == 0)
 102                 ihold(inode);
 103         ++ci->i_wrbuffer_ref;
 104         dout("%p set_page_dirty %p idx %lu head %d/%d -> %d/%d "
 105              "snapc %p seq %lld (%d snaps)\n",
 106              mapping->host, page, page->index,
 107              ci->i_wrbuffer_ref-1, ci->i_wrbuffer_ref_head-1,
 108              ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
 109              snapc, snapc->seq, snapc->num_snaps);
 110         spin_unlock(&ci->i_ceph_lock);
 111
 112         /*
 113          * Reference snap context in page->private.  Also set
 114          * PagePrivate so that we get invalidatepage callback.
 115          */
 116         BUG_ON(PagePrivate(page));
 117         page->private = (unsigned long)snapc;
 118         SetPagePrivate(page);
 119
 120         ret = __set_page_dirty_nobuffers(page);
 121         WARN_ON(!PageLocked(page));
 122         WARN_ON(!page->mapping);
 123
 124         return ret;
 125 }
 126
 127 /*
 128  * If we are truncating the full page (i.e. offset == 0), adjust the
 129  * dirty page counters appropriately.  Only called if there is private
 130  * data on the page.
 131  */
 132 static void ceph_invalidatepage(struct page *page, unsigned int offset,
 133                                 unsigned int length)
 134 {
 135         struct inode *inode;
 136         struct ceph_inode_info *ci;
 137         struct ceph_snap_context *snapc = page_snap_context(page);
 138
 139         inode = page->mapping->host;
 140         ci = ceph_inode(inode);
 141
 142         if (offset != 0 || length != PAGE_CACHE_SIZE) {
 143                 dout("%p invalidatepage %p idx %lu partial dirty page %u~%u\n",
 144                      inode, page, page->index, offset, length);
 145                 return;
 146         }
 147
 148         ceph_invalidate_fscache_page(inode, page);
 149
 150         if (!PagePrivate(page))
 151                 return;
 152
 153         /*
 154          * We can get non-dirty pages here due to races between
 155          * set_page_dirty and truncate_complete_page; just spit out a
 156          * warning, in case we end up with accounting problems later.
 157          */
 158         if (!PageDirty(page))
 159                 pr_err("%p invalidatepage %p page not dirty\n", inode, page);
 160
 161         ClearPageChecked(page);
 162
 163         dout("%p invalidatepage %p idx %lu full dirty page\n",
 164              inode, page, page->index);
 165
 166         ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
 167         ceph_put_snap_context(snapc);
 168         page->private = 0;
 169         ClearPagePrivate(page);
 170 }
 171
 172 static int ceph_releasepage(struct page *page, gfp_t g)
 173 {
 174         struct inode *inode = page->mapping ? page->mapping->host : NULL;
 175         dout("%p releasepage %p idx %lu\n", inode, page, page->index);
 176         WARN_ON(PageDirty(page));
 177
 178         /* Can we release the page from the cache? */
 179         if (!ceph_release_fscache_page(page, g))
 180                 return 0;
 181
 182         return !PagePrivate(page);
 183 }
 184
 185 /*
 186  * read a single page, without unlocking it.
 187  */
 188 static int readpage_nounlock(struct file *filp, struct page *page)
 189 {
 190         struct inode *inode = file_inode(filp);
 191         struct ceph_inode_info *ci = ceph_inode(inode);
 192         struct ceph_osd_client *osdc =
 193                 &ceph_inode_to_client(inode)->client->osdc;
 194         int err = 0;
 195         u64 len = PAGE_CACHE_SIZE;
 196
 197         err = ceph_readpage_from_fscache(inode, page);
 198
 199         if (err == 0)
 200                 goto out;
 201
 202         dout("readpage inode %p file %p page %p index %lu\n",
 203              inode, filp, page, page->index);
 204         err = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
 205                                   (u64) page_offset(page), &len,
 206                                   ci->i_truncate_seq, ci->i_truncate_size,
 207                                   &page, 1, 0);
 208         if (err == -ENOENT)
 209                 err = 0;
 210         if (err < 0) {
 211                 SetPageError(page);
 212                 ceph_fscache_readpage_cancel(inode, page);
 213                 goto out;
 214         } else {
 215                 if (err < PAGE_CACHE_SIZE) {
 216                 /* zero fill remainder of page */
 217                         zero_user_segment(page, err, PAGE_CACHE_SIZE);
 218                 } else {
 219                         flush_dcache_page(page);
 220                 }
 221         }
 222         SetPageUptodate(page);
 223
 224         if (err >= 0)
 225                 ceph_readpage_to_fscache(inode, page);
 226
 227 out:
 228         return err < 0 ? err : 0;
 229 }
 230
 231 static int ceph_readpage(struct file *filp, struct page *page)
 232 {
 233         int r = readpage_nounlock(filp, page);
 234         unlock_page(page);
 235         return r;
 236 }
 237
 238 /*
 239  * Finish an async read(ahead) op.
 240  */
 241 static void finish_read(struct ceph_osd_request *req, struct ceph_msg *msg)
 242 {
 243         struct inode *inode = req->r_inode;
 244         struct ceph_osd_data *osd_data;
 245         int rc = req->r_result;
 246         int bytes = le32_to_cpu(msg->hdr.data_len);
 247         int num_pages;
 248         int i;
 249
 250         dout("finish_read %p req %p rc %d bytes %d\n", inode, req, rc, bytes);
 251
 252         /* unlock all pages, zeroing any data we didn't read */
 253         osd_data = osd_req_op_extent_osd_data(req, 0);
 254         BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);
 255         num_pages = calc_pages_for((u64)osd_data->alignment,
 256                                         (u64)osd_data->length);
 257         for (i = 0; i < num_pages; i++) {
 258                 struct page *page = osd_data->pages[i];
 259
 260                 if (rc < 0)
 261                         goto unlock;
 262                 if (bytes < (int)PAGE_CACHE_SIZE) {
 263                         /* zero (remainder of) page */
 264                         int s = bytes < 0 ? 0 : bytes;
 265                         zero_user_segment(page, s, PAGE_CACHE_SIZE);
 266                 }
 267                 dout("finish_read %p uptodate %p idx %lu\n", inode, page,
 268                      page->index);
 269                 flush_dcache_page(page);
 270                 SetPageUptodate(page);
 271                 ceph_readpage_to_fscache(inode, page);
 272 unlock:
 273                 unlock_page(page);
 274                 page_cache_release(page);
 275                 bytes -= PAGE_CACHE_SIZE;
 276         }
 277         kfree(osd_data->pages);
 278 }
 279
 280 static void ceph_unlock_page_vector(struct page **pages, int num_pages)
 281 {
 282         int i;
 283
 284         for (i = 0; i < num_pages; i++)
 285                 unlock_page(pages[i]);
 286 }
 287
 288 /*
 289  * start an async read(ahead) operation.  return nr_pages we submitted
 290  * a read for on success, or negative error code.
 291  */
 292 static int start_read(struct inode *inode, struct list_head *page_list, int max)
 293 {
 294         struct ceph_osd_client *osdc =
 295                 &ceph_inode_to_client(inode)->client->osdc;
 296         struct ceph_inode_info *ci = ceph_inode(inode);
 297         struct page *page = list_entry(page_list->prev, struct page, lru);
 298         struct ceph_vino vino;
 299         struct ceph_osd_request *req;
 300         u64 off;
 301         u64 len;
 302         int i;
 303         struct page **pages;
 304         pgoff_t next_index;
 305         int nr_pages = 0;
 306         int ret;
 307
 308         off = (u64) page_offset(page);
 309
 310         /* count pages */
 311         next_index = page->index;
 312         list_for_each_entry_reverse(page, page_list, lru) {
 313                 if (page->index != next_index)
 314                         break;
 315                 nr_pages++;
 316                 next_index++;
 317                 if (max && nr_pages == max)
 318                         break;
 319         }
 320         len = nr_pages << PAGE_CACHE_SHIFT;
 321         dout("start_read %p nr_pages %d is %lld~%lld\n", inode, nr_pages,
 322              off, len);
 323         vino = ceph_vino(inode);
 324         req = ceph_osdc_new_request(osdc, &ci->i_layout, vino, off, &len,
 325                                     1, CEPH_OSD_OP_READ,
 326                                     CEPH_OSD_FLAG_READ, NULL,
 327                                     ci->i_truncate_seq, ci->i_truncate_size,
 328                                     false);
 329         if (IS_ERR(req))
 330                 return PTR_ERR(req);
 331
 332         /* build page vector */
 333         nr_pages = calc_pages_for(0, len);
 334         pages = kmalloc(sizeof(*pages) * nr_pages, GFP_NOFS);
 335         ret = -ENOMEM;
 336         if (!pages)
 337                 goto out;
 338         for (i = 0; i < nr_pages; ++i) {
 339                 page = list_entry(page_list->prev, struct page, lru);
 340                 BUG_ON(PageLocked(page));
 341                 list_del(&page->lru);
 342
 343                 dout("start_read %p adding %p idx %lu\n", inode, page,
 344                      page->index);
 345                 if (add_to_page_cache_lru(page, &inode->i_data, page->index,
 346                                           GFP_NOFS)) {
 347                         ceph_fscache_uncache_page(inode, page);
 348                         page_cache_release(page);
 349                         dout("start_read %p add_to_page_cache failed %p\n",
 350                              inode, page);
 351                         nr_pages = i;
 352                         goto out_pages;
 353                 }
 354                 pages[i] = page;
 355         }
 356         osd_req_op_extent_osd_data_pages(req, 0, pages, len, 0, false, false);
 357         req->r_callback = finish_read;
 358         req->r_inode = inode;
 359
 360         ceph_osdc_build_request(req, off, NULL, vino.snap, NULL);
 361
 362         dout("start_read %p starting %p %lld~%lld\n", inode, req, off, len);
 363         ret = ceph_osdc_start_request(osdc, req, false);
 364         if (ret < 0)
 365                 goto out_pages;
 366         ceph_osdc_put_request(req);
 367         return nr_pages;
 368
 369 out_pages:
 370         ceph_unlock_page_vector(pages, nr_pages);
 371         ceph_release_page_vector(pages, nr_pages);
 372 out:
 373         ceph_osdc_put_request(req);
 374         return ret;
 375 }
 376
 377
 378 /*
 379  * Read multiple pages.  Leave pages we don't read + unlock in page_list;
 380  * the caller (VM) cleans them up.
 381  */
 382 static int ceph_readpages(struct file *file, struct address_space *mapping,
 383                           struct list_head *page_list, unsigned nr_pages)
 384 {
 385         struct inode *inode = file_inode(file);
 386         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 387         int rc = 0;
 388         int max = 0;
 389
 390         rc = ceph_readpages_from_fscache(mapping->host, mapping, page_list,
 391                                          &nr_pages);
 392
 393         if (rc == 0)
 394                 goto out;
 395
 396         if (fsc->mount_options->rsize >= PAGE_CACHE_SIZE)
 397                 max = (fsc->mount_options->rsize + PAGE_CACHE_SIZE - 1)
 398                         >> PAGE_SHIFT;
 399
 400         dout("readpages %p file %p nr_pages %d max %d\n", inode,
 401                 file, nr_pages,
 402              max);
 403         while (!list_empty(page_list)) {
 404                 rc = start_read(inode, page_list, max);
 405                 if (rc < 0)
 406                         goto out;
 407                 BUG_ON(rc == 0);
 408         }
 409 out:
 410         ceph_fscache_readpages_cancel(inode, page_list);
 411
 412         dout("readpages %p file %p ret %d\n", inode, file, rc);
 413         return rc;
 414 }
 415
 416 /*
 417  * Get ref for the oldest snapc for an inode with dirty data... that is, the
 418  * only snap context we are allowed to write back.
 419  */
 420 static struct ceph_snap_context *get_oldest_context(struct inode *inode,
 421                                                     u64 *snap_size)
 422 {
 423         struct ceph_inode_info *ci = ceph_inode(inode);
 424         struct ceph_snap_context *snapc = NULL;
 425         struct ceph_cap_snap *capsnap = NULL;
 426
 427         spin_lock(&ci->i_ceph_lock);
 428         list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
 429                 dout(" cap_snap %p snapc %p has %d dirty pages\n", capsnap,
 430                      capsnap->context, capsnap->dirty_pages);
 431                 if (capsnap->dirty_pages) {
 432                         snapc = ceph_get_snap_context(capsnap->context);
 433                         if (snap_size)
 434                                 *snap_size = capsnap->size;
 435                         break;
 436                 }
 437         }
 438         if (!snapc && ci->i_wrbuffer_ref_head) {
 439                 snapc = ceph_get_snap_context(ci->i_head_snapc);
 440                 dout(" head snapc %p has %d dirty pages\n",
 441                      snapc, ci->i_wrbuffer_ref_head);
 442         }
 443         spin_unlock(&ci->i_ceph_lock);
 444         return snapc;
 445 }
 446
 447 /*
 448  * Write a single page, but leave the page locked.
 449  *
 450  * If we get a write error, set the page error bit, but still adjust the
 451  * dirty page accounting (i.e., page is no longer dirty).
 452  */
 453 static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
 454 {
 455         struct inode *inode;
 456         struct ceph_inode_info *ci;
 457         struct ceph_fs_client *fsc;
 458         struct ceph_osd_client *osdc;
 459         struct ceph_snap_context *snapc, *oldest;
 460         loff_t page_off = page_offset(page);
 461         long writeback_stat;
 462         u64 truncate_size, snap_size = 0;
 463         u32 truncate_seq;
 464         int err = 0, len = PAGE_CACHE_SIZE;
 465
 466         dout("writepage %p idx %lu\n", page, page->index);
 467
 468         if (!page->mapping || !page->mapping->host) {
 469                 dout("writepage %p - no mapping\n", page);
 470                 return -EFAULT;
 471         }
 472         inode = page->mapping->host;
 473         ci = ceph_inode(inode);
 474         fsc = ceph_inode_to_client(inode);
 475         osdc = &fsc->client->osdc;
 476
 477         /* verify this is a writeable snap context */
 478         snapc = page_snap_context(page);
 479         if (snapc == NULL) {
 480                 dout("writepage %p page %p not dirty?\n", inode, page);
 481                 goto out;
 482         }
 483         oldest = get_oldest_context(inode, &snap_size);
 484         if (snapc->seq > oldest->seq) {
 485                 dout("writepage %p page %p snapc %p not writeable - noop\n",
 486                      inode, page, snapc);
 487                 /* we should only noop if called by kswapd */
 488                 WARN_ON((current->flags & PF_MEMALLOC) == 0);
 489                 ceph_put_snap_context(oldest);
 490                 goto out;
 491         }
 492         ceph_put_snap_context(oldest);
 493
 494         spin_lock(&ci->i_ceph_lock);
 495         truncate_seq = ci->i_truncate_seq;
 496         truncate_size = ci->i_truncate_size;
 497         if (!snap_size)
 498                 snap_size = i_size_read(inode);
 499         spin_unlock(&ci->i_ceph_lock);
 500
 501         /* is this a partial page at end of file? */
 502         if (page_off >= snap_size) {
 503                 dout("%p page eof %llu\n", page, snap_size);
 504                 goto out;
 505         }
 506         if (snap_size < page_off + len)
 507                 len = snap_size - page_off;
 508
 509         dout("writepage %p page %p index %lu on %llu~%u snapc %p\n",
 510              inode, page, page->index, page_off, len, snapc);
 511
 512         writeback_stat = atomic_long_inc_return(&fsc->writeback_count);
 513         if (writeback_stat >
 514             CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb))
 515                 set_bdi_congested(&fsc->backing_dev_info, BLK_RW_ASYNC);
 516
 517         ceph_readpage_to_fscache(inode, page);
 518
 519         set_page_writeback(page);
 520         err = ceph_osdc_writepages(osdc, ceph_vino(inode),
 521                                    &ci->i_layout, snapc,
 522                                    page_off, len,
 523                                    truncate_seq, truncate_size,
 524                                    &inode->i_mtime, &page, 1);
 525         if (err < 0) {
 526                 dout("writepage setting page/mapping error %d %p\n", err, page);
 527                 SetPageError(page);
 528                 mapping_set_error(&inode->i_data, err);
 529                 if (wbc)
 530                         wbc->pages_skipped++;
 531         } else {
 532                 dout("writepage cleaned page %p\n", page);
 533                 err = 0;  /* vfs expects us to return 0 */
 534         }
 535         page->private = 0;
 536         ClearPagePrivate(page);
 537         end_page_writeback(page);
 538         ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
 539         ceph_put_snap_context(snapc);  /* page's reference */
 540 out:
 541         return err;
 542 }
 543
 544 static int ceph_writepage(struct page *page, struct writeback_control *wbc)
 545 {
 546         int err;
 547         struct inode *inode = page->mapping->host;
 548         BUG_ON(!inode);
 549         ihold(inode);
 550         err = writepage_nounlock(page, wbc);
 551         unlock_page(page);
 552         iput(inode);
 553         return err;
 554 }
 555
 556
 557 /*
 558  * lame release_pages helper.  release_pages() isn't exported to
 559  * modules.
 560  */
 561 static void ceph_release_pages(struct page **pages, int num)
 562 {
 563         struct pagevec pvec;
 564         int i;
 565
 566         pagevec_init(&pvec, 0);
 567         for (i = 0; i < num; i++) {
 568                 if (pagevec_add(&pvec, pages[i]) == 0)
 569                         pagevec_release(&pvec);
 570         }
 571         pagevec_release(&pvec);
 572 }
 573
 574 /*
 575  * async writeback completion handler.
 576  *
 577  * If we get an error, set the mapping error bit, but not the individual
 578  * page error bits.
 579  */
 580 static void writepages_finish(struct ceph_osd_request *req,
 581                               struct ceph_msg *msg)
 582 {
 583         struct inode *inode = req->r_inode;
 584         struct ceph_inode_info *ci = ceph_inode(inode);
 585         struct ceph_osd_data *osd_data;
 586         unsigned wrote;
 587         struct page *page;
 588         int num_pages;
 589         int i;
 590         struct ceph_snap_context *snapc = req->r_snapc;
 591         struct address_space *mapping = inode->i_mapping;
 592         int rc = req->r_result;
 593         u64 bytes = req->r_ops[0].extent.length;
 594         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 595         long writeback_stat;
 596         unsigned issued = ceph_caps_issued(ci);
 597
 598         osd_data = osd_req_op_extent_osd_data(req, 0);
 599         BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);
 600         num_pages = calc_pages_for((u64)osd_data->alignment,
 601                                         (u64)osd_data->length);
 602         if (rc >= 0) {
 603                 /*
 604                  * Assume we wrote the pages we originally sent.  The
 605                  * osd might reply with fewer pages if our writeback
 606                  * raced with a truncation and was adjusted at the osd,
 607                  * so don't believe the reply.
 608                  */
 609                 wrote = num_pages;
 610         } else {
 611                 wrote = 0;
 612                 mapping_set_error(mapping, rc);
 613         }
 614         dout("writepages_finish %p rc %d bytes %llu wrote %d (pages)\n",
 615              inode, rc, bytes, wrote);
 616
 617         /* clean all pages */
 618         for (i = 0; i < num_pages; i++) {
 619                 page = osd_data->pages[i];
 620                 BUG_ON(!page);
 621                 WARN_ON(!PageUptodate(page));
 622
 623                 writeback_stat =
 624                         atomic_long_dec_return(&fsc->writeback_count);
 625                 if (writeback_stat <
 626                     CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
 627                         clear_bdi_congested(&fsc->backing_dev_info,
 628                                             BLK_RW_ASYNC);
 629
 630                 ceph_put_snap_context(page_snap_context(page));
 631                 page->private = 0;
 632                 ClearPagePrivate(page);
 633                 dout("unlocking %d %p\n", i, page);
 634                 end_page_writeback(page);
 635
 636                 /*
 637                  * We lost the cache cap, need to truncate the page before
 638                  * it is unlocked, otherwise we'd truncate it later in the
 639                  * page truncation thread, possibly losing some data that
 640                  * raced its way in
 641                  */
 642                 if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0)
 643                         generic_error_remove_page(inode->i_mapping, page);
 644
 645                 unlock_page(page);
 646         }
 647         dout("%p wrote+cleaned %d pages\n", inode, wrote);
 648         ceph_put_wrbuffer_cap_refs(ci, num_pages, snapc);
 649
 650         ceph_release_pages(osd_data->pages, num_pages);
 651         if (osd_data->pages_from_pool)
 652                 mempool_free(osd_data->pages,
 653                              ceph_sb_to_client(inode->i_sb)->wb_pagevec_pool);
 654         else
 655                 kfree(osd_data->pages);
 656         ceph_osdc_put_request(req);
 657 }
 658
 659 /*
 660  * initiate async writeback
 661  */
 662 static int ceph_writepages_start(struct address_space *mapping,
 663                                  struct writeback_control *wbc)
 664 {
 665         struct inode *inode = mapping->host;
 666         struct ceph_inode_info *ci = ceph_inode(inode);
 667         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 668         struct ceph_vino vino = ceph_vino(inode);
 669         pgoff_t index, start, end;
 670         int range_whole = 0;
 671         int should_loop = 1;
 672         pgoff_t max_pages = 0, max_pages_ever = 0;
 673         struct ceph_snap_context *snapc = NULL, *last_snapc = NULL, *pgsnapc;
 674         struct pagevec pvec;
 675         int done = 0;
 676         int rc = 0;
 677         unsigned wsize = 1 << inode->i_blkbits;
 678         struct ceph_osd_request *req = NULL;
 679         int do_sync;
 680         u64 truncate_size, snap_size;
 681         u32 truncate_seq;
 682
 683         /*
 684          * Include a 'sync' in the OSD request if this is a data
 685          * integrity write (e.g., O_SYNC write or fsync()), or if our
 686          * cap is being revoked.
 687          */
 688         if ((wbc->sync_mode == WB_SYNC_ALL) ||
 689                 ceph_caps_revoking(ci, CEPH_CAP_FILE_BUFFER))
 690                 do_sync = 1;
 691         dout("writepages_start %p dosync=%d (mode=%s)\n",
 692              inode, do_sync,
 693              wbc->sync_mode == WB_SYNC_NONE ? "NONE" :
 694              (wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD"));
 695
 696         if (fsc->mount_state == CEPH_MOUNT_SHUTDOWN) {
 697                 pr_warning("writepage_start %p on forced umount\n", inode);
 698                 return -EIO; /* we're in a forced umount, don't write! */
 699         }
 700         if (fsc->mount_options->wsize && fsc->mount_options->wsize < wsize)
 701                 wsize = fsc->mount_options->wsize;
 702         if (wsize < PAGE_CACHE_SIZE)
 703                 wsize = PAGE_CACHE_SIZE;
 704         max_pages_ever = wsize >> PAGE_CACHE_SHIFT;
 705
 706         pagevec_init(&pvec, 0);
 707
 708         /* where to start/end? */
 709         if (wbc->range_cyclic) {
 710                 start = mapping->writeback_index; /* Start from prev offset */
 711                 end = -1;
 712                 dout(" cyclic, start at %lu\n", start);
 713         } else {
 714                 start = wbc->range_start >> PAGE_CACHE_SHIFT;
 715                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
 716                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 717                         range_whole = 1;
 718                 should_loop = 0;
 719                 dout(" not cyclic, %lu to %lu\n", start, end);
 720         }
 721         index = start;
 722
 723 retry:
 724         /* find oldest snap context with dirty data */
 725         ceph_put_snap_context(snapc);
 726         snap_size = 0;
 727         snapc = get_oldest_context(inode, &snap_size);
 728         if (!snapc) {
 729                 /* hmm, why does writepages get called when there
 730                    is no dirty data? */
 731                 dout(" no snap context with dirty data?\n");
 732                 goto out;
 733         }
 734         if (snap_size == 0)
 735                 snap_size = i_size_read(inode);
 736         dout(" oldest snapc is %p seq %lld (%d snaps)\n",
 737              snapc, snapc->seq, snapc->num_snaps);
 738
 739         spin_lock(&ci->i_ceph_lock);
 740         truncate_seq = ci->i_truncate_seq;
 741         truncate_size = ci->i_truncate_size;
 742         if (!snap_size)
 743                 snap_size = i_size_read(inode);
 744         spin_unlock(&ci->i_ceph_lock);
 745
 746         if (last_snapc && snapc != last_snapc) {
 747                 /* if we switched to a newer snapc, restart our scan at the
 748                  * start of the original file range. */
 749                 dout("  snapc differs from last pass, restarting at %lu\n",
 750                      index);
 751                 index = start;
 752         }
 753         last_snapc = snapc;
 754
 755         while (!done && index <= end) {
 756                 int num_ops = do_sync ? 2 : 1;
 757                 unsigned i;
 758                 int first;
 759                 pgoff_t next;
 760                 int pvec_pages, locked_pages;
 761                 struct page **pages = NULL;
 762                 mempool_t *pool = NULL; /* Becomes non-null if mempool used */
 763                 struct page *page;
 764                 int want;
 765                 u64 offset, len;
 766                 long writeback_stat;
 767
 768                 next = 0;
 769                 locked_pages = 0;
 770                 max_pages = max_pages_ever;
 771
 772 get_more_pages:
 773                 first = -1;
 774                 want = min(end - index,
 775                            min((pgoff_t)PAGEVEC_SIZE,
 776                                max_pages - (pgoff_t)locked_pages) - 1)
 777                         + 1;
 778                 pvec_pages = pagevec_lookup_tag(&pvec, mapping, &index,
 779                                                 PAGECACHE_TAG_DIRTY,
 780                                                 want);
 781                 dout("pagevec_lookup_tag got %d\n", pvec_pages);
 782                 if (!pvec_pages && !locked_pages)
 783                         break;
 784                 for (i = 0; i < pvec_pages && locked_pages < max_pages; i++) {
 785                         page = pvec.pages[i];
 786                         dout("? %p idx %lu\n", page, page->index);
 787                         if (locked_pages == 0)
 788                                 lock_page(page);  /* first page */
 789                         else if (!trylock_page(page))
 790                                 break;
 791
 792                         /* only dirty pages, or our accounting breaks */
 793                         if (unlikely(!PageDirty(page)) ||
 794                             unlikely(page->mapping != mapping)) {
 795                                 dout("!dirty or !mapping %p\n", page);
 796                                 unlock_page(page);
 797                                 break;
 798                         }
 799                         if (!wbc->range_cyclic && page->index > end) {
 800                                 dout("end of range %p\n", page);
 801                                 done = 1;
 802                                 unlock_page(page);
 803                                 break;
 804                         }
 805                         if (next && (page->index != next)) {
 806                                 dout("not consecutive %p\n", page);
 807                                 unlock_page(page);
 808                                 break;
 809                         }
 810                         if (wbc->sync_mode != WB_SYNC_NONE) {
 811                                 dout("waiting on writeback %p\n", page);
 812                                 wait_on_page_writeback(page);
 813                         }
 814                         if (page_offset(page) >= snap_size) {
 815                                 dout("%p page eof %llu\n", page, snap_size);
 816                                 done = 1;
 817                                 unlock_page(page);
 818                                 break;
 819                         }
 820                         if (PageWriteback(page)) {
 821                                 dout("%p under writeback\n", page);
 822                                 unlock_page(page);
 823                                 break;
 824                         }
 825
 826                         /* only if matching snap context */
 827                         pgsnapc = page_snap_context(page);
 828                         if (pgsnapc->seq > snapc->seq) {
 829                                 dout("page snapc %p %lld > oldest %p %lld\n",
 830                                      pgsnapc, pgsnapc->seq, snapc, snapc->seq);
 831                                 unlock_page(page);
 832                                 if (!locked_pages)
 833                                         continue; /* keep looking for snap */
 834                                 break;
 835                         }
 836
 837                         if (!clear_page_dirty_for_io(page)) {
 838                                 dout("%p !clear_page_dirty_for_io\n", page);
 839                                 unlock_page(page);
 840                                 break;
 841                         }
 842
 843                         /*
 844                          * We have something to write.  If this is
 845                          * the first locked page this time through,
 846                          * allocate an osd request and a page array
 847                          * that it will use.
 848                          */
 849                         if (locked_pages == 0) {
 850                                 BUG_ON(pages);
 851                                 /* prepare async write request */
 852                                 offset = (u64)page_offset(page);
 853                                 len = wsize;
 854                                 req = ceph_osdc_new_request(&fsc->client->osdc,
 855                                                         &ci->i_layout, vino,
 856                                                         offset, &len, num_ops,
 857                                                         CEPH_OSD_OP_WRITE,
 858                                                         CEPH_OSD_FLAG_WRITE |
 859                                                         CEPH_OSD_FLAG_ONDISK,
 860                                                         snapc, truncate_seq,
 861                                                         truncate_size, true);
 862                                 if (IS_ERR(req)) {
 863                                         rc = PTR_ERR(req);
 864                                         unlock_page(page);
 865                                         break;
 866                                 }
 867
 868                                 req->r_callback = writepages_finish;
 869                                 req->r_inode = inode;
 870
 871                                 max_pages = calc_pages_for(0, (u64)len);
 872                                 pages = kmalloc(max_pages * sizeof (*pages),
 873                                                 GFP_NOFS);
 874                                 if (!pages) {
 875                                         pool = fsc->wb_pagevec_pool;
 876                                         pages = mempool_alloc(pool, GFP_NOFS);
 877                                         BUG_ON(!pages);
 878                                 }
 879                         }
 880
 881                         /* note position of first page in pvec */
 882                         if (first < 0)
 883                                 first = i;
 884                         dout("%p will write page %p idx %lu\n",
 885                              inode, page, page->index);
 886
 887                         writeback_stat =
 888                                atomic_long_inc_return(&fsc->writeback_count);
 889                         if (writeback_stat > CONGESTION_ON_THRESH(
 890                                     fsc->mount_options->congestion_kb)) {
 891                                 set_bdi_congested(&fsc->backing_dev_info,
 892                                                   BLK_RW_ASYNC);
 893                         }
 894
 895                         set_page_writeback(page);
 896                         pages[locked_pages] = page;
 897                         locked_pages++;
 898                         next = page->index + 1;
 899                 }
 900
 901                 /* did we get anything? */
 902                 if (!locked_pages)
 903                         goto release_pvec_pages;
 904                 if (i) {
 905                         int j;
 906                         BUG_ON(!locked_pages || first < 0);
 907
 908                         if (pvec_pages && i == pvec_pages &&
 909                             locked_pages < max_pages) {
 910                                 dout("reached end pvec, trying for more\n");
 911                                 pagevec_reinit(&pvec);
 912                                 goto get_more_pages;
 913                         }
 914
 915                         /* shift unused pages over in the pvec...  we
 916                          * will need to release them below. */
 917                         for (j = i; j < pvec_pages; j++) {
 918                                 dout(" pvec leftover page %p\n",
 919                                      pvec.pages[j]);
 920                                 pvec.pages[j-i+first] = pvec.pages[j];
 921                         }
 922                         pvec.nr -= i-first;
 923                 }
 924
 925                 /* Format the osd request message and submit the write */
 926
 927                 offset = page_offset(pages[0]);
 928                 len = min(snap_size - offset,
 929                           (u64)locked_pages << PAGE_CACHE_SHIFT);
 930                 dout("writepages got %d pages at %llu~%llu\n",
 931                      locked_pages, offset, len);
 932
 933                 osd_req_op_extent_osd_data_pages(req, 0, pages, len, 0,
 934                                                         !!pool, false);
 935
 936                 pages = NULL;   /* request message now owns the pages array */
 937                 pool = NULL;
 938
 939                 /* Update the write op length in case we changed it */
 940
 941                 osd_req_op_extent_update(req, 0, len);
 942
 943                 vino = ceph_vino(inode);
 944                 ceph_osdc_build_request(req, offset, snapc, vino.snap,
 945                                         &inode->i_mtime);
 946
 947                 rc = ceph_osdc_start_request(&fsc->client->osdc, req, true);
 948                 BUG_ON(rc);
 949                 req = NULL;
 950
 951                 /* continue? */
 952                 index = next;
 953                 wbc->nr_to_write -= locked_pages;
 954                 if (wbc->nr_to_write <= 0)
 955                         done = 1;
 956
 957 release_pvec_pages:
 958                 dout("pagevec_release on %d pages (%p)\n", (int)pvec.nr,
 959                      pvec.nr ? pvec.pages[0] : NULL);
 960                 pagevec_release(&pvec);
 961
 962                 if (locked_pages && !done)
 963                         goto retry;
 964         }
 965
 966         if (should_loop && !done) {
 967                 /* more to do; loop back to beginning of file */
 968                 dout("writepages looping back to beginning of file\n");
 969                 should_loop = 0;
 970                 index = 0;
 971                 goto retry;
 972         }
 973
 974         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 975                 mapping->writeback_index = index;
 976
 977 out:
 978         if (req)
 979                 ceph_osdc_put_request(req);
 980         ceph_put_snap_context(snapc);
 981         dout("writepages done, rc = %d\n", rc);
 982         return rc;
 983 }
 984
 985
 986
 987 /*
 988  * See if a given @snapc is either writeable, or already written.
 989  */
 990 static int context_is_writeable_or_written(struct inode *inode,
 991                                            struct ceph_snap_context *snapc)
 992 {
 993         struct ceph_snap_context *oldest = get_oldest_context(inode, NULL);
 994         int ret = !oldest || snapc->seq <= oldest->seq;
 995
 996         ceph_put_snap_context(oldest);
 997         return ret;
 998 }
 999
1000 /*
1001  * We are only allowed to write into/dirty the page if the page is
1002  * clean, or already dirty within the same snap context.
1003  *
1004  * called with page locked.
1005  * return success with page locked,
1006  * or any failure (incl -EAGAIN) with page unlocked.
1007  */
1008 static int ceph_update_writeable_page(struct file *file,
1009                             loff_t pos, unsigned len,
1010                             struct page *page)
1011 {
1012         struct inode *inode = file_inode(file);
1013         struct ceph_inode_info *ci = ceph_inode(inode);
1014         struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
1015         loff_t page_off = pos & PAGE_CACHE_MASK;
1016         int pos_in_page = pos & ~PAGE_CACHE_MASK;
1017         int end_in_page = pos_in_page + len;
1018         loff_t i_size;
1019         int r;
1020         struct ceph_snap_context *snapc, *oldest;
1021
1022 retry_locked:
1023         /* writepages currently holds page lock, but if we change that later, */
1024         wait_on_page_writeback(page);
1025
1026         /* check snap context */
1027         BUG_ON(!ci->i_snap_realm);
1028         down_read(&mdsc->snap_rwsem);
1029         BUG_ON(!ci->i_snap_realm->cached_context);
1030         snapc = page_snap_context(page);
1031         if (snapc && snapc != ci->i_head_snapc) {
1032                 /*
1033                  * this page is already dirty in another (older) snap
1034                  * context!  is it writeable now?
1035                  */
1036                 oldest = get_oldest_context(inode, NULL);
1037                 up_read(&mdsc->snap_rwsem);
1038
1039                 if (snapc->seq > oldest->seq) {
1040                         ceph_put_snap_context(oldest);
1041                         dout(" page %p snapc %p not current or oldest\n",
1042                              page, snapc);
1043                         /*
1044                          * queue for writeback, and wait for snapc to
1045                          * be writeable or written
1046                          */
1047                         snapc = ceph_get_snap_context(snapc);
1048                         unlock_page(page);
1049                         ceph_queue_writeback(inode);
1050                         r = wait_event_interruptible(ci->i_cap_wq,
1051                                context_is_writeable_or_written(inode, snapc));
1052                         ceph_put_snap_context(snapc);
1053                         if (r == -ERESTARTSYS)
1054                                 return r;
1055                         return -EAGAIN;
1056                 }
1057                 ceph_put_snap_context(oldest);
1058
1059                 /* yay, writeable, do it now (without dropping page lock) */
1060                 dout(" page %p snapc %p not current, but oldest\n",
1061                      page, snapc);
1062                 if (!clear_page_dirty_for_io(page))
1063                         goto retry_locked;
1064                 r = writepage_nounlock(page, NULL);
1065                 if (r < 0)
1066                         goto fail_nosnap;
1067                 goto retry_locked;
1068         }
1069
1070         if (PageUptodate(page)) {
1071                 dout(" page %p already uptodate\n", page);
1072                 return 0;
1073         }
1074
1075         /* full page? */
1076         if (pos_in_page == 0 && len == PAGE_CACHE_SIZE)
1077                 return 0;
1078
1079         /* past end of file? */
1080         i_size = inode->i_size;   /* caller holds i_mutex */
1081
1082         if (i_size + len > inode->i_sb->s_maxbytes) {
1083                 /* file is too big */
1084                 r = -EINVAL;
1085                 goto fail;
1086         }
1087
1088         if (page_off >= i_size ||
1089             (pos_in_page == 0 && (pos+len) >= i_size &&
1090              end_in_page - pos_in_page != PAGE_CACHE_SIZE)) {
1091                 dout(" zeroing %p 0 - %d and %d - %d\n",
1092                      page, pos_in_page, end_in_page, (int)PAGE_CACHE_SIZE);
1093                 zero_user_segments(page,
1094                                    0, pos_in_page,
1095                                    end_in_page, PAGE_CACHE_SIZE);
1096                 return 0;
1097         }
1098
1099         /* we need to read it. */
1100         up_read(&mdsc->snap_rwsem);
1101         r = readpage_nounlock(file, page);
1102         if (r < 0)
1103                 goto fail_nosnap;
1104         goto retry_locked;
1105
1106 fail:
1107         up_read(&mdsc->snap_rwsem);
1108 fail_nosnap:
1109         unlock_page(page);
1110         return r;
1111 }
1112
1113 /*
1114  * We are only allowed to write into/dirty the page if the page is
1115  * clean, or already dirty within the same snap context.
1116  */
1117 static int ceph_write_begin(struct file *file, struct address_space *mapping,
1118                             loff_t pos, unsigned len, unsigned flags,
1119                             struct page **pagep, void **fsdata)
1120 {
1121         struct inode *inode = file_inode(file);
1122         struct page *page;
1123         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1124         int r;
1125
1126         do {
1127                 /* get a page */
1128                 page = grab_cache_page_write_begin(mapping, index, 0);
1129                 if (!page)
1130                         return -ENOMEM;
1131                 *pagep = page;
1132
1133                 dout("write_begin file %p inode %p page %p %d~%d\n", file,
1134                      inode, page, (int)pos, (int)len);
1135
1136                 r = ceph_update_writeable_page(file, pos, len, page);
1137         } while (r == -EAGAIN);
1138
1139         return r;
1140 }
1141
1142 /*
1143  * we don't do anything in here that simple_write_end doesn't do
1144  * except adjust dirty page accounting and drop read lock on
1145  * mdsc->snap_rwsem.
1146  */
1147 static int ceph_write_end(struct file *file, struct address_space *mapping,
1148                           loff_t pos, unsigned len, unsigned copied,
1149                           struct page *page, void *fsdata)
1150 {
1151         struct inode *inode = file_inode(file);
1152         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
1153         struct ceph_mds_client *mdsc = fsc->mdsc;
1154         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1155         int check_cap = 0;
1156
1157         dout("write_end file %p inode %p page %p %d~%d (%d)\n", file,
1158              inode, page, (int)pos, (int)copied, (int)len);
1159
1160         /* zero the stale part of the page if we did a short copy */
1161         if (copied < len)
1162                 zero_user_segment(page, from+copied, len);
1163
1164         /* did file size increase? */
1165         /* (no need for i_size_read(); we caller holds i_mutex */
1166         if (pos+copied > inode->i_size)
1167                 check_cap = ceph_inode_set_size(inode, pos+copied);
1168
1169         if (!PageUptodate(page))
1170                 SetPageUptodate(page);
1171
1172         set_page_dirty(page);
1173
1174         unlock_page(page);
1175         up_read(&mdsc->snap_rwsem);
1176         page_cache_release(page);
1177
1178         if (check_cap)
1179                 ceph_check_caps(ceph_inode(inode), CHECK_CAPS_AUTHONLY, NULL);
1180
1181         return copied;
1182 }
1183
1184 /*
1185  * we set .direct_IO to indicate direct io is supported, but since we
1186  * intercept O_DIRECT reads and writes early, this function should
1187  * never get called.
1188  */
1189 static ssize_t ceph_direct_io(int rw, struct kiocb *iocb,
1190                               const struct iovec *iov,
1191                               loff_t pos, unsigned long nr_segs)
1192 {
1193         WARN_ON(1);
1194         return -EINVAL;
1195 }
1196
1197 const struct address_space_operations ceph_aops = {
1198         .readpage = ceph_readpage,
1199         .readpages = ceph_readpages,
1200         .writepage = ceph_writepage,
1201         .writepages = ceph_writepages_start,
1202         .write_begin = ceph_write_begin,
1203         .write_end = ceph_write_end,
1204         .set_page_dirty = ceph_set_page_dirty,
1205         .invalidatepage = ceph_invalidatepage,
1206         .releasepage = ceph_releasepage,
1207         .direct_IO = ceph_direct_io,
1208 };
1209
1210
1211 /*
1212  * vm ops
1213  */
1214 static int ceph_filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1215 {
1216         struct inode *inode = file_inode(vma->vm_file);
1217         struct ceph_inode_info *ci = ceph_inode(inode);
1218         struct ceph_file_info *fi = vma->vm_file->private_data;
1219         loff_t off = vmf->pgoff << PAGE_CACHE_SHIFT;
1220         int want, got, ret;
1221
1222         dout("filemap_fault %p %llx.%llx %llu~%zd trying to get caps\n",
1223              inode, ceph_vinop(inode), off, (size_t)PAGE_CACHE_SIZE);
1224         if (fi->fmode & CEPH_FILE_MODE_LAZY)
1225                 want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;
1226         else
1227                 want = CEPH_CAP_FILE_CACHE;
1228         while (1) {
1229                 got = 0;
1230                 ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, want, &got, -1);
1231                 if (ret == 0)
1232                         break;
1233                 if (ret != -ERESTARTSYS) {
1234                         WARN_ON(1);
1235                         return VM_FAULT_SIGBUS;
1236                 }
1237         }
1238         dout("filemap_fault %p %llu~%zd got cap refs on %s\n",
1239              inode, off, (size_t)PAGE_CACHE_SIZE, ceph_cap_string(got));
1240
1241         ret = filemap_fault(vma, vmf);
1242
1243         dout("filemap_fault %p %llu~%zd dropping cap refs on %s ret %d\n",
1244              inode, off, (size_t)PAGE_CACHE_SIZE, ceph_cap_string(got), ret);
1245         ceph_put_cap_refs(ci, got);
1246
1247         return ret;
1248 }
1249
1250 /*
1251  * Reuse write_begin here for simplicity.
1252  */
1253 static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
1254 {
1255         struct inode *inode = file_inode(vma->vm_file);
1256         struct ceph_inode_info *ci = ceph_inode(inode);
1257         struct ceph_file_info *fi = vma->vm_file->private_data;
1258         struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
1259         struct page *page = vmf->page;
1260         loff_t off = page_offset(page);
1261         loff_t size = i_size_read(inode);
1262         size_t len;
1263         int want, got, ret;
1264
1265         if (off + PAGE_CACHE_SIZE <= size)
1266                 len = PAGE_CACHE_SIZE;
1267         else
1268                 len = size & ~PAGE_CACHE_MASK;
1269
1270         dout("page_mkwrite %p %llx.%llx %llu~%zd getting caps i_size %llu\n",
1271              inode, ceph_vinop(inode), off, len, size);
1272         if (fi->fmode & CEPH_FILE_MODE_LAZY)
1273                 want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
1274         else
1275                 want = CEPH_CAP_FILE_BUFFER;
1276         while (1) {
1277                 got = 0;
1278                 ret = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, &got, off + len);
1279                 if (ret == 0)
1280                         break;
1281                 if (ret != -ERESTARTSYS) {
1282                         WARN_ON(1);
1283                         return VM_FAULT_SIGBUS;
1284                 }
1285         }
1286         dout("page_mkwrite %p %llu~%zd got cap refs on %s\n",
1287              inode, off, len, ceph_cap_string(got));
1288
1289         /* Update time before taking page lock */
1290         file_update_time(vma->vm_file);
1291
1292         lock_page(page);
1293
1294         ret = VM_FAULT_NOPAGE;
1295         if ((off > size) ||
1296             (page->mapping != inode->i_mapping))
1297                 goto out;
1298
1299         ret = ceph_update_writeable_page(vma->vm_file, off, len, page);
1300         if (ret == 0) {
1301                 /* success.  we'll keep the page locked. */
1302                 set_page_dirty(page);
1303                 up_read(&mdsc->snap_rwsem);
1304                 ret = VM_FAULT_LOCKED;
1305         } else {
1306                 if (ret == -ENOMEM)
1307                         ret = VM_FAULT_OOM;
1308                 else
1309                         ret = VM_FAULT_SIGBUS;
1310         }
1311 out:
1312         if (ret != VM_FAULT_LOCKED) {
1313                 unlock_page(page);
1314         } else {
1315                 int dirty;
1316                 spin_lock(&ci->i_ceph_lock);
1317                 dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR);
1318                 spin_unlock(&ci->i_ceph_lock);
1319                 if (dirty)
1320                         __mark_inode_dirty(inode, dirty);
1321         }
1322
1323         dout("page_mkwrite %p %llu~%zd dropping cap refs on %s ret %d\n",
1324              inode, off, len, ceph_cap_string(got), ret);
1325         ceph_put_cap_refs(ci, got);
1326
1327         return ret;
1328 }
1329
1330 static struct vm_operations_struct ceph_vmops = {
1331         .fault          = ceph_filemap_fault,
1332         .page_mkwrite   = ceph_page_mkwrite,
1333         .remap_pages    = generic_file_remap_pages,
1334 };
1335
1336 int ceph_mmap(struct file *file, struct vm_area_struct *vma)
1337 {
1338         struct address_space *mapping = file->f_mapping;
1339
1340         if (!mapping->a_ops->readpage)
1341                 return -ENOEXEC;
1342         file_accessed(file);
1343         vma->vm_ops = &ceph_vmops;
1344         return 0;
1345 }