fs/ceph/addr.c

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