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 <linux/ceph/osd_client.h>
  15
  16 /*
  17  * Ceph address space ops.
  18  *
  19  * There are a few funny things going on here.
  20  *
  21  * The page->private field is used to reference a struct
  22  * ceph_snap_context for _every_ dirty page.  This indicates which
  23  * snapshot the page was logically dirtied in, and thus which snap
  24  * context needs to be associated with the osd write during writeback.
  25  *
  26  * Similarly, struct ceph_inode_info maintains a set of counters to
  27  * count dirty pages on the inode.  In the absense of snapshots,
  28  * i_wrbuffer_ref == i_wrbuffer_ref_head == the dirty page count.
  29  *
  30  * When a snapshot is taken (that is, when the client receives
  31  * notification that a snapshot was taken), each inode with caps and
  32  * with dirty pages (dirty pages implies there is a cap) gets a new
  33  * ceph_cap_snap in the i_cap_snaps list (which is sorted in ascending
  34  * order, new snaps go to the tail).  The i_wrbuffer_ref_head count is
  35  * moved to capsnap->dirty. (Unless a sync write is currently in
  36  * progress.  In that case, the capsnap is said to be "pending", new
  37  * writes cannot start, and the capsnap isn't "finalized" until the
  38  * write completes (or fails) and a final size/mtime for the inode for
  39  * that snap can be settled upon.)  i_wrbuffer_ref_head is reset to 0.
  40  *
  41  * On writeback, we must submit writes to the osd IN SNAP ORDER.  So,
  42  * we look for the first capsnap in i_cap_snaps and write out pages in
  43  * that snap context _only_.  Then we move on to the next capsnap,
  44  * eventually reaching the "live" or "head" context (i.e., pages that
  45  * are not yet snapped) and are writing the most recently dirtied
  46  * pages.
  47  *
  48  * Invalidate and so forth must take care to ensure the dirty page
  49  * accounting is preserved.
  50  */
  51
  52 #define CONGESTION_ON_THRESH(congestion_kb) (congestion_kb >> (PAGE_SHIFT-10))
  53 #define CONGESTION_OFF_THRESH(congestion_kb)                            \
  54         (CONGESTION_ON_THRESH(congestion_kb) -                          \
  55          (CONGESTION_ON_THRESH(congestion_kb) >> 2))
  56
  57
  58
  59 /*
  60  * Dirty a page.  Optimistically adjust accounting, on the assumption
  61  * that we won't race with invalidate.  If we do, readjust.
  62  */
  63 static int ceph_set_page_dirty(struct page *page)
  64 {
  65         struct address_space *mapping = page->mapping;
  66         struct inode *inode;
  67         struct ceph_inode_info *ci;
  68         int undo = 0;
  69         struct ceph_snap_context *snapc;
  70
  71         if (unlikely(!mapping))
  72                 return !TestSetPageDirty(page);
  73
  74         if (TestSetPageDirty(page)) {
  75                 dout("%p set_page_dirty %p idx %lu -- already dirty\n",
  76                      mapping->host, page, page->index);
  77                 return 0;
  78         }
  79
  80         inode = mapping->host;
  81         ci = ceph_inode(inode);
  82
  83         /*
  84          * Note that we're grabbing a snapc ref here without holding
  85          * any locks!
  86          */
  87         snapc = ceph_get_snap_context(ci->i_snap_realm->cached_context);
  88
  89         /* dirty the head */
  90         spin_lock(&inode->i_lock);
  91         if (ci->i_head_snapc == NULL)
  92                 ci->i_head_snapc = ceph_get_snap_context(snapc);
  93         ++ci->i_wrbuffer_ref_head;
  94         if (ci->i_wrbuffer_ref == 0)
  95                 igrab(inode);
  96         ++ci->i_wrbuffer_ref;
  97         dout("%p set_page_dirty %p idx %lu head %d/%d -> %d/%d "
  98              "snapc %p seq %lld (%d snaps)\n",
  99              mapping->host, page, page->index,
 100              ci->i_wrbuffer_ref-1, ci->i_wrbuffer_ref_head-1,
 101              ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
 102              snapc, snapc->seq, snapc->num_snaps);
 103         spin_unlock(&inode->i_lock);
 104
 105         /* now adjust page */
 106         spin_lock_irq(&mapping->tree_lock);
 107         if (page->mapping) {    /* Race with truncate? */
 108                 WARN_ON_ONCE(!PageUptodate(page));
 109                 account_page_dirtied(page, page->mapping);
 110                 radix_tree_tag_set(&mapping->page_tree,
 111                                 page_index(page), PAGECACHE_TAG_DIRTY);
 112
 113                 /*
 114                  * Reference snap context in page->private.  Also set
 115                  * PagePrivate so that we get invalidatepage callback.
 116                  */
 117                 page->private = (unsigned long)snapc;
 118                 SetPagePrivate(page);
 119         } else {
 120                 dout("ANON set_page_dirty %p (raced truncate?)\n", page);
 121                 undo = 1;
 122         }
 123
 124         spin_unlock_irq(&mapping->tree_lock);
 125
 126         if (undo)
 127                 /* whoops, we failed to dirty the page */
 128                 ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
 129
 130         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
 131
 132         BUG_ON(!PageDirty(page));
 133         return 1;
 134 }
 135
 136 /*
 137  * If we are truncating the full page (i.e. offset == 0), adjust the
 138  * dirty page counters appropriately.  Only called if there is private
 139  * data on the page.
 140  */
 141 static void ceph_invalidatepage(struct page *page, unsigned long offset)
 142 {
 143         struct inode *inode;
 144         struct ceph_inode_info *ci;
 145         struct ceph_snap_context *snapc = (void *)page->private;
 146
 147         BUG_ON(!PageLocked(page));
 148         BUG_ON(!page->private);
 149         BUG_ON(!PagePrivate(page));
 150         BUG_ON(!page->mapping);
 151
 152         inode = page->mapping->host;
 153
 154         /*
 155          * We can get non-dirty pages here due to races between
 156          * set_page_dirty and truncate_complete_page; just spit out a
 157          * warning, in case we end up with accounting problems later.
 158          */
 159         if (!PageDirty(page))
 160                 pr_err("%p invalidatepage %p page not dirty\n", inode, page);
 161
 162         if (offset == 0)
 163                 ClearPageChecked(page);
 164
 165         ci = ceph_inode(inode);
 166         if (offset == 0) {
 167                 dout("%p invalidatepage %p idx %lu full dirty page %lu\n",
 168                      inode, page, page->index, offset);
 169                 ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
 170                 ceph_put_snap_context(snapc);
 171                 page->private = 0;
 172                 ClearPagePrivate(page);
 173         } else {
 174                 dout("%p invalidatepage %p idx %lu partial dirty page\n",
 175                      inode, page, page->index);
 176         }
 177 }
 178
 179 /* just a sanity check */
 180 static int ceph_releasepage(struct page *page, gfp_t g)
 181 {
 182         struct inode *inode = page->mapping ? page->mapping->host : NULL;
 183         dout("%p releasepage %p idx %lu\n", inode, page, page->index);
 184         WARN_ON(PageDirty(page));
 185         WARN_ON(page->private);
 186         WARN_ON(PagePrivate(page));
 187         return 0;
 188 }
 189
 190 /*
 191  * read a single page, without unlocking it.
 192  */
 193 static int readpage_nounlock(struct file *filp, struct page *page)
 194 {
 195         struct inode *inode = filp->f_dentry->d_inode;
 196         struct ceph_inode_info *ci = ceph_inode(inode);
 197         struct ceph_osd_client *osdc =
 198                 &ceph_inode_to_client(inode)->client->osdc;
 199         int err = 0;
 200         u64 len = PAGE_CACHE_SIZE;
 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                                   page->index << PAGE_CACHE_SHIFT, &len,
 206                                   ci->i_truncate_seq, ci->i_truncate_size,
 207                                   &page, 1);
 208         if (err == -ENOENT)
 209                 err = 0;
 210         if (err < 0) {
 211                 SetPageError(page);
 212                 goto out;
 213         } else if (err < PAGE_CACHE_SIZE) {
 214                 /* zero fill remainder of page */
 215                 zero_user_segment(page, err, PAGE_CACHE_SIZE);
 216         }
 217         SetPageUptodate(page);
 218
 219 out:
 220         return err < 0 ? err : 0;
 221 }
 222
 223 static int ceph_readpage(struct file *filp, struct page *page)
 224 {
 225         int r = readpage_nounlock(filp, page);
 226         unlock_page(page);
 227         return r;
 228 }
 229
 230 /*
 231  * Build a vector of contiguous pages from the provided page list.
 232  */
 233 static struct page **page_vector_from_list(struct list_head *page_list,
 234                                            unsigned *nr_pages)
 235 {
 236         struct page **pages;
 237         struct page *page;
 238         int next_index, contig_pages = 0;
 239
 240         /* build page vector */
 241         pages = kmalloc(sizeof(*pages) * *nr_pages, GFP_NOFS);
 242         if (!pages)
 243                 return ERR_PTR(-ENOMEM);
 244
 245         BUG_ON(list_empty(page_list));
 246         next_index = list_entry(page_list->prev, struct page, lru)->index;
 247         list_for_each_entry_reverse(page, page_list, lru) {
 248                 if (page->index == next_index) {
 249                         dout("readpages page %d %p\n", contig_pages, page);
 250                         pages[contig_pages] = page;
 251                         contig_pages++;
 252                         next_index++;
 253                 } else {
 254                         break;
 255                 }
 256         }
 257         *nr_pages = contig_pages;
 258         return pages;
 259 }
 260
 261 /*
 262  * Read multiple pages.  Leave pages we don't read + unlock in page_list;
 263  * the caller (VM) cleans them up.
 264  */
 265 static int ceph_readpages(struct file *file, struct address_space *mapping,
 266                           struct list_head *page_list, unsigned nr_pages)
 267 {
 268         struct inode *inode = file->f_dentry->d_inode;
 269         struct ceph_inode_info *ci = ceph_inode(inode);
 270         struct ceph_osd_client *osdc =
 271                 &ceph_inode_to_client(inode)->client->osdc;
 272         int rc = 0;
 273         struct page **pages;
 274         loff_t offset;
 275         u64 len;
 276
 277         dout("readpages %p file %p nr_pages %d\n",
 278              inode, file, nr_pages);
 279
 280         pages = page_vector_from_list(page_list, &nr_pages);
 281         if (IS_ERR(pages))
 282                 return PTR_ERR(pages);
 283
 284         /* guess read extent */
 285         offset = pages[0]->index << PAGE_CACHE_SHIFT;
 286         len = nr_pages << PAGE_CACHE_SHIFT;
 287         rc = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
 288                                  offset, &len,
 289                                  ci->i_truncate_seq, ci->i_truncate_size,
 290                                  pages, nr_pages);
 291         if (rc == -ENOENT)
 292                 rc = 0;
 293         if (rc < 0)
 294                 goto out;
 295
 296         for (; !list_empty(page_list) && len > 0;
 297              rc -= PAGE_CACHE_SIZE, len -= PAGE_CACHE_SIZE) {
 298                 struct page *page =
 299                         list_entry(page_list->prev, struct page, lru);
 300
 301                 list_del(&page->lru);
 302
 303                 if (rc < (int)PAGE_CACHE_SIZE) {
 304                         /* zero (remainder of) page */
 305                         int s = rc < 0 ? 0 : rc;
 306                         zero_user_segment(page, s, PAGE_CACHE_SIZE);
 307                 }
 308
 309                 if (add_to_page_cache_lru(page, mapping, page->index,
 310                                           GFP_NOFS)) {
 311                         page_cache_release(page);
 312                         dout("readpages %p add_to_page_cache failed %p\n",
 313                              inode, page);
 314                         continue;
 315                 }
 316                 dout("readpages %p adding %p idx %lu\n", inode, page,
 317                      page->index);
 318                 flush_dcache_page(page);
 319                 SetPageUptodate(page);
 320                 unlock_page(page);
 321                 page_cache_release(page);
 322         }
 323         rc = 0;
 324
 325 out:
 326         kfree(pages);
 327         return rc;
 328 }
 329
 330 /*
 331  * Get ref for the oldest snapc for an inode with dirty data... that is, the
 332  * only snap context we are allowed to write back.
 333  */
 334 static struct ceph_snap_context *get_oldest_context(struct inode *inode,
 335                                                     u64 *snap_size)
 336 {
 337         struct ceph_inode_info *ci = ceph_inode(inode);
 338         struct ceph_snap_context *snapc = NULL;
 339         struct ceph_cap_snap *capsnap = NULL;
 340
 341         spin_lock(&inode->i_lock);
 342         list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
 343                 dout(" cap_snap %p snapc %p has %d dirty pages\n", capsnap,
 344                      capsnap->context, capsnap->dirty_pages);
 345                 if (capsnap->dirty_pages) {
 346                         snapc = ceph_get_snap_context(capsnap->context);
 347                         if (snap_size)
 348                                 *snap_size = capsnap->size;
 349                         break;
 350                 }
 351         }
 352         if (!snapc && ci->i_wrbuffer_ref_head) {
 353                 snapc = ceph_get_snap_context(ci->i_head_snapc);
 354                 dout(" head snapc %p has %d dirty pages\n",
 355                      snapc, ci->i_wrbuffer_ref_head);
 356         }
 357         spin_unlock(&inode->i_lock);
 358         return snapc;
 359 }
 360
 361 /*
 362  * Write a single page, but leave the page locked.
 363  *
 364  * If we get a write error, set the page error bit, but still adjust the
 365  * dirty page accounting (i.e., page is no longer dirty).
 366  */
 367 static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
 368 {
 369         struct inode *inode;
 370         struct ceph_inode_info *ci;
 371         struct ceph_fs_client *fsc;
 372         struct ceph_osd_client *osdc;
 373         loff_t page_off = page->index << PAGE_CACHE_SHIFT;
 374         int len = PAGE_CACHE_SIZE;
 375         loff_t i_size;
 376         int err = 0;
 377         struct ceph_snap_context *snapc, *oldest;
 378         u64 snap_size = 0;
 379         long writeback_stat;
 380
 381         dout("writepage %p idx %lu\n", page, page->index);
 382
 383         if (!page->mapping || !page->mapping->host) {
 384                 dout("writepage %p - no mapping\n", page);
 385                 return -EFAULT;
 386         }
 387         inode = page->mapping->host;
 388         ci = ceph_inode(inode);
 389         fsc = ceph_inode_to_client(inode);
 390         osdc = &fsc->client->osdc;
 391
 392         /* verify this is a writeable snap context */
 393         snapc = (void *)page->private;
 394         if (snapc == NULL) {
 395                 dout("writepage %p page %p not dirty?\n", inode, page);
 396                 goto out;
 397         }
 398         oldest = get_oldest_context(inode, &snap_size);
 399         if (snapc->seq > oldest->seq) {
 400                 dout("writepage %p page %p snapc %p not writeable - noop\n",
 401                      inode, page, (void *)page->private);
 402                 /* we should only noop if called by kswapd */
 403                 WARN_ON((current->flags & PF_MEMALLOC) == 0);
 404                 ceph_put_snap_context(oldest);
 405                 goto out;
 406         }
 407         ceph_put_snap_context(oldest);
 408
 409         /* is this a partial page at end of file? */
 410         if (snap_size)
 411                 i_size = snap_size;
 412         else
 413                 i_size = i_size_read(inode);
 414         if (i_size < page_off + len)
 415                 len = i_size - page_off;
 416
 417         dout("writepage %p page %p index %lu on %llu~%u snapc %p\n",
 418              inode, page, page->index, page_off, len, snapc);
 419
 420         writeback_stat = atomic_long_inc_return(&fsc->writeback_count);
 421         if (writeback_stat >
 422             CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb))
 423                 set_bdi_congested(&fsc->backing_dev_info, BLK_RW_ASYNC);
 424
 425         set_page_writeback(page);
 426         err = ceph_osdc_writepages(osdc, ceph_vino(inode),
 427                                    &ci->i_layout, snapc,
 428                                    page_off, len,
 429                                    ci->i_truncate_seq, ci->i_truncate_size,
 430                                    &inode->i_mtime,
 431                                    &page, 1, 0, 0, true);
 432         if (err < 0) {
 433                 dout("writepage setting page/mapping error %d %p\n", err, page);
 434                 SetPageError(page);
 435                 mapping_set_error(&inode->i_data, err);
 436                 if (wbc)
 437                         wbc->pages_skipped++;
 438         } else {
 439                 dout("writepage cleaned page %p\n", page);
 440                 err = 0;  /* vfs expects us to return 0 */
 441         }
 442         page->private = 0;
 443         ClearPagePrivate(page);
 444         end_page_writeback(page);
 445         ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
 446         ceph_put_snap_context(snapc);  /* page's reference */
 447 out:
 448         return err;
 449 }
 450
 451 static int ceph_writepage(struct page *page, struct writeback_control *wbc)
 452 {
 453         int err;
 454         struct inode *inode = page->mapping->host;
 455         BUG_ON(!inode);
 456         igrab(inode);
 457         err = writepage_nounlock(page, wbc);
 458         unlock_page(page);
 459         iput(inode);
 460         return err;
 461 }
 462
 463
 464 /*
 465  * lame release_pages helper.  release_pages() isn't exported to
 466  * modules.
 467  */
 468 static void ceph_release_pages(struct page **pages, int num)
 469 {
 470         struct pagevec pvec;
 471         int i;
 472
 473         pagevec_init(&pvec, 0);
 474         for (i = 0; i < num; i++) {
 475                 if (pagevec_add(&pvec, pages[i]) == 0)
 476                         pagevec_release(&pvec);
 477         }
 478         pagevec_release(&pvec);
 479 }
 480
 481
 482 /*
 483  * async writeback completion handler.
 484  *
 485  * If we get an error, set the mapping error bit, but not the individual
 486  * page error bits.
 487  */
 488 static void writepages_finish(struct ceph_osd_request *req,
 489                               struct ceph_msg *msg)
 490 {
 491         struct inode *inode = req->r_inode;
 492         struct ceph_osd_reply_head *replyhead;
 493         struct ceph_osd_op *op;
 494         struct ceph_inode_info *ci = ceph_inode(inode);
 495         unsigned wrote;
 496         struct page *page;
 497         int i;
 498         struct ceph_snap_context *snapc = req->r_snapc;
 499         struct address_space *mapping = inode->i_mapping;
 500         __s32 rc = -EIO;
 501         u64 bytes = 0;
 502         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 503         long writeback_stat;
 504         unsigned issued = ceph_caps_issued(ci);
 505
 506         /* parse reply */
 507         replyhead = msg->front.iov_base;
 508         WARN_ON(le32_to_cpu(replyhead->num_ops) == 0);
 509         op = (void *)(replyhead + 1);
 510         rc = le32_to_cpu(replyhead->result);
 511         bytes = le64_to_cpu(op->extent.length);
 512
 513         if (rc >= 0) {
 514                 /*
 515                  * Assume we wrote the pages we originally sent.  The
 516                  * osd might reply with fewer pages if our writeback
 517                  * raced with a truncation and was adjusted at the osd,
 518                  * so don't believe the reply.
 519                  */
 520                 wrote = req->r_num_pages;
 521         } else {
 522                 wrote = 0;
 523                 mapping_set_error(mapping, rc);
 524         }
 525         dout("writepages_finish %p rc %d bytes %llu wrote %d (pages)\n",
 526              inode, rc, bytes, wrote);
 527
 528         /* clean all pages */
 529         for (i = 0; i < req->r_num_pages; i++) {
 530                 page = req->r_pages[i];
 531                 BUG_ON(!page);
 532                 WARN_ON(!PageUptodate(page));
 533
 534                 writeback_stat =
 535                         atomic_long_dec_return(&fsc->writeback_count);
 536                 if (writeback_stat <
 537                     CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
 538                         clear_bdi_congested(&fsc->backing_dev_info,
 539                                             BLK_RW_ASYNC);
 540
 541                 ceph_put_snap_context((void *)page->private);
 542                 page->private = 0;
 543                 ClearPagePrivate(page);
 544                 dout("unlocking %d %p\n", i, page);
 545                 end_page_writeback(page);
 546
 547                 /*
 548                  * We lost the cache cap, need to truncate the page before
 549                  * it is unlocked, otherwise we'd truncate it later in the
 550                  * page truncation thread, possibly losing some data that
 551                  * raced its way in
 552                  */
 553                 if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0)
 554                         generic_error_remove_page(inode->i_mapping, page);
 555
 556                 unlock_page(page);
 557         }
 558         dout("%p wrote+cleaned %d pages\n", inode, wrote);
 559         ceph_put_wrbuffer_cap_refs(ci, req->r_num_pages, snapc);
 560
 561         ceph_release_pages(req->r_pages, req->r_num_pages);
 562         if (req->r_pages_from_pool)
 563                 mempool_free(req->r_pages,
 564                              ceph_sb_to_client(inode->i_sb)->wb_pagevec_pool);
 565         else
 566                 kfree(req->r_pages);
 567         ceph_osdc_put_request(req);
 568 }
 569
 570 /*
 571  * allocate a page vec, either directly, or if necessary, via a the
 572  * mempool.  we avoid the mempool if we can because req->r_num_pages
 573  * may be less than the maximum write size.
 574  */
 575 static void alloc_page_vec(struct ceph_fs_client *fsc,
 576                            struct ceph_osd_request *req)
 577 {
 578         req->r_pages = kmalloc(sizeof(struct page *) * req->r_num_pages,
 579                                GFP_NOFS);
 580         if (!req->r_pages) {
 581                 req->r_pages = mempool_alloc(fsc->wb_pagevec_pool, GFP_NOFS);
 582                 req->r_pages_from_pool = 1;
 583                 WARN_ON(!req->r_pages);
 584         }
 585 }
 586
 587 /*
 588  * initiate async writeback
 589  */
 590 static int ceph_writepages_start(struct address_space *mapping,
 591                                  struct writeback_control *wbc)
 592 {
 593         struct inode *inode = mapping->host;
 594         struct backing_dev_info *bdi = mapping->backing_dev_info;
 595         struct ceph_inode_info *ci = ceph_inode(inode);
 596         struct ceph_fs_client *fsc;
 597         pgoff_t index, start, end;
 598         int range_whole = 0;
 599         int should_loop = 1;
 600         pgoff_t max_pages = 0, max_pages_ever = 0;
 601         struct ceph_snap_context *snapc = NULL, *last_snapc = NULL, *pgsnapc;
 602         struct pagevec pvec;
 603         int done = 0;
 604         int rc = 0;
 605         unsigned wsize = 1 << inode->i_blkbits;
 606         struct ceph_osd_request *req = NULL;
 607         int do_sync;
 608         u64 snap_size = 0;
 609
 610         /*
 611          * Include a 'sync' in the OSD request if this is a data
 612          * integrity write (e.g., O_SYNC write or fsync()), or if our
 613          * cap is being revoked.
 614          */
 615         do_sync = wbc->sync_mode == WB_SYNC_ALL;
 616         if (ceph_caps_revoking(ci, CEPH_CAP_FILE_BUFFER))
 617                 do_sync = 1;
 618         dout("writepages_start %p dosync=%d (mode=%s)\n",
 619              inode, do_sync,
 620              wbc->sync_mode == WB_SYNC_NONE ? "NONE" :
 621              (wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD"));
 622
 623         fsc = ceph_inode_to_client(inode);
 624         if (fsc->mount_state == CEPH_MOUNT_SHUTDOWN) {
 625                 pr_warning("writepage_start %p on forced umount\n", inode);
 626                 return -EIO; /* we're in a forced umount, don't write! */
 627         }
 628         if (fsc->mount_options->wsize && fsc->mount_options->wsize < wsize)
 629                 wsize = fsc->mount_options->wsize;
 630         if (wsize < PAGE_CACHE_SIZE)
 631                 wsize = PAGE_CACHE_SIZE;
 632         max_pages_ever = wsize >> PAGE_CACHE_SHIFT;
 633
 634         pagevec_init(&pvec, 0);
 635
 636         /* ?? */
 637         if (wbc->nonblocking && bdi_write_congested(bdi)) {
 638                 dout(" writepages congested\n");
 639                 wbc->encountered_congestion = 1;
 640                 goto out_final;
 641         }
 642
 643         /* where to start/end? */
 644         if (wbc->range_cyclic) {
 645                 start = mapping->writeback_index; /* Start from prev offset */
 646                 end = -1;
 647                 dout(" cyclic, start at %lu\n", start);
 648         } else {
 649                 start = wbc->range_start >> PAGE_CACHE_SHIFT;
 650                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
 651                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 652                         range_whole = 1;
 653                 should_loop = 0;
 654                 dout(" not cyclic, %lu to %lu\n", start, end);
 655         }
 656         index = start;
 657
 658 retry:
 659         /* find oldest snap context with dirty data */
 660         ceph_put_snap_context(snapc);
 661         snapc = get_oldest_context(inode, &snap_size);
 662         if (!snapc) {
 663                 /* hmm, why does writepages get called when there
 664                    is no dirty data? */
 665                 dout(" no snap context with dirty data?\n");
 666                 goto out;
 667         }
 668         dout(" oldest snapc is %p seq %lld (%d snaps)\n",
 669              snapc, snapc->seq, snapc->num_snaps);
 670         if (last_snapc && snapc != last_snapc) {
 671                 /* if we switched to a newer snapc, restart our scan at the
 672                  * start of the original file range. */
 673                 dout("  snapc differs from last pass, restarting at %lu\n",
 674                      index);
 675                 index = start;
 676         }
 677         last_snapc = snapc;
 678
 679         while (!done && index <= end) {
 680                 unsigned i;
 681                 int first;
 682                 pgoff_t next;
 683                 int pvec_pages, locked_pages;
 684                 struct page *page;
 685                 int want;
 686                 u64 offset, len;
 687                 struct ceph_osd_request_head *reqhead;
 688                 struct ceph_osd_op *op;
 689                 long writeback_stat;
 690
 691                 next = 0;
 692                 locked_pages = 0;
 693                 max_pages = max_pages_ever;
 694
 695 get_more_pages:
 696                 first = -1;
 697                 want = min(end - index,
 698                            min((pgoff_t)PAGEVEC_SIZE,
 699                                max_pages - (pgoff_t)locked_pages) - 1)
 700                         + 1;
 701                 pvec_pages = pagevec_lookup_tag(&pvec, mapping, &index,
 702                                                 PAGECACHE_TAG_DIRTY,
 703                                                 want);
 704                 dout("pagevec_lookup_tag got %d\n", pvec_pages);
 705                 if (!pvec_pages && !locked_pages)
 706                         break;
 707                 for (i = 0; i < pvec_pages && locked_pages < max_pages; i++) {
 708                         page = pvec.pages[i];
 709                         dout("? %p idx %lu\n", page, page->index);
 710                         if (locked_pages == 0)
 711                                 lock_page(page);  /* first page */
 712                         else if (!trylock_page(page))
 713                                 break;
 714
 715                         /* only dirty pages, or our accounting breaks */
 716                         if (unlikely(!PageDirty(page)) ||
 717                             unlikely(page->mapping != mapping)) {
 718                                 dout("!dirty or !mapping %p\n", page);
 719                                 unlock_page(page);
 720                                 break;
 721                         }
 722                         if (!wbc->range_cyclic && page->index > end) {
 723                                 dout("end of range %p\n", page);
 724                                 done = 1;
 725                                 unlock_page(page);
 726                                 break;
 727                         }
 728                         if (next && (page->index != next)) {
 729                                 dout("not consecutive %p\n", page);
 730                                 unlock_page(page);
 731                                 break;
 732                         }
 733                         if (wbc->sync_mode != WB_SYNC_NONE) {
 734                                 dout("waiting on writeback %p\n", page);
 735                                 wait_on_page_writeback(page);
 736                         }
 737                         if ((snap_size && page_offset(page) > snap_size) ||
 738                             (!snap_size &&
 739                              page_offset(page) > i_size_read(inode))) {
 740                                 dout("%p page eof %llu\n", page, snap_size ?
 741                                      snap_size : i_size_read(inode));
 742                                 done = 1;
 743                                 unlock_page(page);
 744                                 break;
 745                         }
 746                         if (PageWriteback(page)) {
 747                                 dout("%p under writeback\n", page);
 748                                 unlock_page(page);
 749                                 break;
 750                         }
 751
 752                         /* only if matching snap context */
 753                         pgsnapc = (void *)page->private;
 754                         if (pgsnapc->seq > snapc->seq) {
 755                                 dout("page snapc %p %lld > oldest %p %lld\n",
 756                                      pgsnapc, pgsnapc->seq, snapc, snapc->seq);
 757                                 unlock_page(page);
 758                                 if (!locked_pages)
 759                                         continue; /* keep looking for snap */
 760                                 break;
 761                         }
 762
 763                         if (!clear_page_dirty_for_io(page)) {
 764                                 dout("%p !clear_page_dirty_for_io\n", page);
 765                                 unlock_page(page);
 766                                 break;
 767                         }
 768
 769                         /* ok */
 770                         if (locked_pages == 0) {
 771                                 /* prepare async write request */
 772                                 offset = (unsigned long long)page->index
 773                                         << PAGE_CACHE_SHIFT;
 774                                 len = wsize;
 775                                 req = ceph_osdc_new_request(&fsc->client->osdc,
 776                                             &ci->i_layout,
 777                                             ceph_vino(inode),
 778                                             offset, &len,
 779                                             CEPH_OSD_OP_WRITE,
 780                                             CEPH_OSD_FLAG_WRITE |
 781                                                     CEPH_OSD_FLAG_ONDISK,
 782                                             snapc, do_sync,
 783                                             ci->i_truncate_seq,
 784                                             ci->i_truncate_size,
 785                                             &inode->i_mtime, true, 1);
 786                                 max_pages = req->r_num_pages;
 787
 788                                 alloc_page_vec(fsc, req);
 789                                 req->r_callback = writepages_finish;
 790                                 req->r_inode = inode;
 791                         }
 792
 793                         /* note position of first page in pvec */
 794                         if (first < 0)
 795                                 first = i;
 796                         dout("%p will write page %p idx %lu\n",
 797                              inode, page, page->index);
 798
 799                         writeback_stat =
 800                                atomic_long_inc_return(&fsc->writeback_count);
 801                         if (writeback_stat > CONGESTION_ON_THRESH(
 802                                     fsc->mount_options->congestion_kb)) {
 803                                 set_bdi_congested(&fsc->backing_dev_info,
 804                                                   BLK_RW_ASYNC);
 805                         }
 806
 807                         set_page_writeback(page);
 808                         req->r_pages[locked_pages] = page;
 809                         locked_pages++;
 810                         next = page->index + 1;
 811                 }
 812
 813                 /* did we get anything? */
 814                 if (!locked_pages)
 815                         goto release_pvec_pages;
 816                 if (i) {
 817                         int j;
 818                         BUG_ON(!locked_pages || first < 0);
 819
 820                         if (pvec_pages && i == pvec_pages &&
 821                             locked_pages < max_pages) {
 822                                 dout("reached end pvec, trying for more\n");
 823                                 pagevec_reinit(&pvec);
 824                                 goto get_more_pages;
 825                         }
 826
 827                         /* shift unused pages over in the pvec...  we
 828                          * will need to release them below. */
 829                         for (j = i; j < pvec_pages; j++) {
 830                                 dout(" pvec leftover page %p\n",
 831                                      pvec.pages[j]);
 832                                 pvec.pages[j-i+first] = pvec.pages[j];
 833                         }
 834                         pvec.nr -= i-first;
 835                 }
 836
 837                 /* submit the write */
 838                 offset = req->r_pages[0]->index << PAGE_CACHE_SHIFT;
 839                 len = min((snap_size ? snap_size : i_size_read(inode)) - offset,
 840                           (u64)locked_pages << PAGE_CACHE_SHIFT);
 841                 dout("writepages got %d pages at %llu~%llu\n",
 842                      locked_pages, offset, len);
 843
 844                 /* revise final length, page count */
 845                 req->r_num_pages = locked_pages;
 846                 reqhead = req->r_request->front.iov_base;
 847                 op = (void *)(reqhead + 1);
 848                 op->extent.length = cpu_to_le64(len);
 849                 op->payload_len = cpu_to_le32(len);
 850                 req->r_request->hdr.data_len = cpu_to_le32(len);
 851
 852                 ceph_osdc_start_request(&fsc->client->osdc, req, true);
 853                 req = NULL;
 854
 855                 /* continue? */
 856                 index = next;
 857                 wbc->nr_to_write -= locked_pages;
 858                 if (wbc->nr_to_write <= 0)
 859                         done = 1;
 860
 861 release_pvec_pages:
 862                 dout("pagevec_release on %d pages (%p)\n", (int)pvec.nr,
 863                      pvec.nr ? pvec.pages[0] : NULL);
 864                 pagevec_release(&pvec);
 865
 866                 if (locked_pages && !done)
 867                         goto retry;
 868         }
 869
 870         if (should_loop && !done) {
 871                 /* more to do; loop back to beginning of file */
 872                 dout("writepages looping back to beginning of file\n");
 873                 should_loop = 0;
 874                 index = 0;
 875                 goto retry;
 876         }
 877
 878         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 879                 mapping->writeback_index = index;
 880
 881 out:
 882         if (req)
 883                 ceph_osdc_put_request(req);
 884         if (rc > 0)
 885                 rc = 0;  /* vfs expects us to return 0 */
 886         ceph_put_snap_context(snapc);
 887         dout("writepages done, rc = %d\n", rc);
 888 out_final:
 889         return rc;
 890 }
 891
 892
 893
 894 /*
 895  * See if a given @snapc is either writeable, or already written.
 896  */
 897 static int context_is_writeable_or_written(struct inode *inode,
 898                                            struct ceph_snap_context *snapc)
 899 {
 900         struct ceph_snap_context *oldest = get_oldest_context(inode, NULL);
 901         int ret = !oldest || snapc->seq <= oldest->seq;
 902
 903         ceph_put_snap_context(oldest);
 904         return ret;
 905 }
 906
 907 /*
 908  * We are only allowed to write into/dirty the page if the page is
 909  * clean, or already dirty within the same snap context.
 910  *
 911  * called with page locked.
 912  * return success with page locked,
 913  * or any failure (incl -EAGAIN) with page unlocked.
 914  */
 915 static int ceph_update_writeable_page(struct file *file,
 916                             loff_t pos, unsigned len,
 917                             struct page *page)
 918 {
 919         struct inode *inode = file->f_dentry->d_inode;
 920         struct ceph_inode_info *ci = ceph_inode(inode);
 921         struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
 922         loff_t page_off = pos & PAGE_CACHE_MASK;
 923         int pos_in_page = pos & ~PAGE_CACHE_MASK;
 924         int end_in_page = pos_in_page + len;
 925         loff_t i_size;
 926         int r;
 927         struct ceph_snap_context *snapc, *oldest;
 928
 929 retry_locked:
 930         /* writepages currently holds page lock, but if we change that later, */
 931         wait_on_page_writeback(page);
 932
 933         /* check snap context */
 934         BUG_ON(!ci->i_snap_realm);
 935         down_read(&mdsc->snap_rwsem);
 936         BUG_ON(!ci->i_snap_realm->cached_context);
 937         snapc = (void *)page->private;
 938         if (snapc && snapc != ci->i_head_snapc) {
 939                 /*
 940                  * this page is already dirty in another (older) snap
 941                  * context!  is it writeable now?
 942                  */
 943                 oldest = get_oldest_context(inode, NULL);
 944                 up_read(&mdsc->snap_rwsem);
 945
 946                 if (snapc->seq > oldest->seq) {
 947                         ceph_put_snap_context(oldest);
 948                         dout(" page %p snapc %p not current or oldest\n",
 949                              page, snapc);
 950                         /*
 951                          * queue for writeback, and wait for snapc to
 952                          * be writeable or written
 953                          */
 954                         snapc = ceph_get_snap_context(snapc);
 955                         unlock_page(page);
 956                         ceph_queue_writeback(inode);
 957                         r = wait_event_interruptible(ci->i_cap_wq,
 958                                context_is_writeable_or_written(inode, snapc));
 959                         ceph_put_snap_context(snapc);
 960                         if (r == -ERESTARTSYS)
 961                                 return r;
 962                         return -EAGAIN;
 963                 }
 964                 ceph_put_snap_context(oldest);
 965
 966                 /* yay, writeable, do it now (without dropping page lock) */
 967                 dout(" page %p snapc %p not current, but oldest\n",
 968                      page, snapc);
 969                 if (!clear_page_dirty_for_io(page))
 970                         goto retry_locked;
 971                 r = writepage_nounlock(page, NULL);
 972                 if (r < 0)
 973                         goto fail_nosnap;
 974                 goto retry_locked;
 975         }
 976
 977         if (PageUptodate(page)) {
 978                 dout(" page %p already uptodate\n", page);
 979                 return 0;
 980         }
 981
 982         /* full page? */
 983         if (pos_in_page == 0 && len == PAGE_CACHE_SIZE)
 984                 return 0;
 985
 986         /* past end of file? */
 987         i_size = inode->i_size;   /* caller holds i_mutex */
 988
 989         if (i_size + len > inode->i_sb->s_maxbytes) {
 990                 /* file is too big */
 991                 r = -EINVAL;
 992                 goto fail;
 993         }
 994
 995         if (page_off >= i_size ||
 996             (pos_in_page == 0 && (pos+len) >= i_size &&
 997              end_in_page - pos_in_page != PAGE_CACHE_SIZE)) {
 998                 dout(" zeroing %p 0 - %d and %d - %d\n",
 999                      page, pos_in_page, end_in_page, (int)PAGE_CACHE_SIZE);
1000                 zero_user_segments(page,
1001                                    0, pos_in_page,
1002                                    end_in_page, PAGE_CACHE_SIZE);
1003                 return 0;
1004         }
1005
1006         /* we need to read it. */
1007         up_read(&mdsc->snap_rwsem);
1008         r = readpage_nounlock(file, page);
1009         if (r < 0)
1010                 goto fail_nosnap;
1011         goto retry_locked;
1012
1013 fail:
1014         up_read(&mdsc->snap_rwsem);
1015 fail_nosnap:
1016         unlock_page(page);
1017         return r;
1018 }
1019
1020 /*
1021  * We are only allowed to write into/dirty the page if the page is
1022  * clean, or already dirty within the same snap context.
1023  */
1024 static int ceph_write_begin(struct file *file, struct address_space *mapping,
1025                             loff_t pos, unsigned len, unsigned flags,
1026                             struct page **pagep, void **fsdata)
1027 {
1028         struct inode *inode = file->f_dentry->d_inode;
1029         struct page *page;
1030         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1031         int r;
1032
1033         do {
1034                 /* get a page */
1035                 page = grab_cache_page_write_begin(mapping, index, 0);
1036                 if (!page)
1037                         return -ENOMEM;
1038                 *pagep = page;
1039
1040                 dout("write_begin file %p inode %p page %p %d~%d\n", file,
1041                      inode, page, (int)pos, (int)len);
1042
1043                 r = ceph_update_writeable_page(file, pos, len, page);
1044         } while (r == -EAGAIN);
1045
1046         return r;
1047 }
1048
1049 /*
1050  * we don't do anything in here that simple_write_end doesn't do
1051  * except adjust dirty page accounting and drop read lock on
1052  * mdsc->snap_rwsem.
1053  */
1054 static int ceph_write_end(struct file *file, struct address_space *mapping,
1055                           loff_t pos, unsigned len, unsigned copied,
1056                           struct page *page, void *fsdata)
1057 {
1058         struct inode *inode = file->f_dentry->d_inode;
1059         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
1060         struct ceph_mds_client *mdsc = fsc->mdsc;
1061         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1062         int check_cap = 0;
1063
1064         dout("write_end file %p inode %p page %p %d~%d (%d)\n", file,
1065              inode, page, (int)pos, (int)copied, (int)len);
1066
1067         /* zero the stale part of the page if we did a short copy */
1068         if (copied < len)
1069                 zero_user_segment(page, from+copied, len);
1070
1071         /* did file size increase? */
1072         /* (no need for i_size_read(); we caller holds i_mutex */
1073         if (pos+copied > inode->i_size)
1074                 check_cap = ceph_inode_set_size(inode, pos+copied);
1075
1076         if (!PageUptodate(page))
1077                 SetPageUptodate(page);
1078
1079         set_page_dirty(page);
1080
1081         unlock_page(page);
1082         up_read(&mdsc->snap_rwsem);
1083         page_cache_release(page);
1084
1085         if (check_cap)
1086                 ceph_check_caps(ceph_inode(inode), CHECK_CAPS_AUTHONLY, NULL);
1087
1088         return copied;
1089 }
1090
1091 /*
1092  * we set .direct_IO to indicate direct io is supported, but since we
1093  * intercept O_DIRECT reads and writes early, this function should
1094  * never get called.
1095  */
1096 static ssize_t ceph_direct_io(int rw, struct kiocb *iocb,
1097                               const struct iovec *iov,
1098                               loff_t pos, unsigned long nr_segs)
1099 {
1100         WARN_ON(1);
1101         return -EINVAL;
1102 }
1103
1104 const struct address_space_operations ceph_aops = {
1105         .readpage = ceph_readpage,
1106         .readpages = ceph_readpages,
1107         .writepage = ceph_writepage,
1108         .writepages = ceph_writepages_start,
1109         .write_begin = ceph_write_begin,
1110         .write_end = ceph_write_end,
1111         .set_page_dirty = ceph_set_page_dirty,
1112         .invalidatepage = ceph_invalidatepage,
1113         .releasepage = ceph_releasepage,
1114         .direct_IO = ceph_direct_io,
1115 };
1116
1117
1118 /*
1119  * vm ops
1120  */
1121
1122 /*
1123  * Reuse write_begin here for simplicity.
1124  */
1125 static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
1126 {
1127         struct inode *inode = vma->vm_file->f_dentry->d_inode;
1128         struct page *page = vmf->page;
1129         struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
1130         loff_t off = page->index << PAGE_CACHE_SHIFT;
1131         loff_t size, len;
1132         int ret;
1133
1134         size = i_size_read(inode);
1135         if (off + PAGE_CACHE_SIZE <= size)
1136                 len = PAGE_CACHE_SIZE;
1137         else
1138                 len = size & ~PAGE_CACHE_MASK;
1139
1140         dout("page_mkwrite %p %llu~%llu page %p idx %lu\n", inode,
1141              off, len, page, page->index);
1142
1143         lock_page(page);
1144
1145         ret = VM_FAULT_NOPAGE;
1146         if ((off > size) ||
1147             (page->mapping != inode->i_mapping))
1148                 goto out;
1149
1150         ret = ceph_update_writeable_page(vma->vm_file, off, len, page);
1151         if (ret == 0) {
1152                 /* success.  we'll keep the page locked. */
1153                 set_page_dirty(page);
1154                 up_read(&mdsc->snap_rwsem);
1155                 ret = VM_FAULT_LOCKED;
1156         } else {
1157                 if (ret == -ENOMEM)
1158                         ret = VM_FAULT_OOM;
1159                 else
1160                         ret = VM_FAULT_SIGBUS;
1161         }
1162 out:
1163         dout("page_mkwrite %p %llu~%llu = %d\n", inode, off, len, ret);
1164         if (ret != VM_FAULT_LOCKED)
1165                 unlock_page(page);
1166         return ret;
1167 }
1168
1169 static struct vm_operations_struct ceph_vmops = {
1170         .fault          = filemap_fault,
1171         .page_mkwrite   = ceph_page_mkwrite,
1172 };
1173
1174 int ceph_mmap(struct file *file, struct vm_area_struct *vma)
1175 {
1176         struct address_space *mapping = file->f_mapping;
1177
1178         if (!mapping->a_ops->readpage)
1179                 return -ENOEXEC;
1180         file_accessed(file);
1181         vma->vm_ops = &ceph_vmops;
1182         vma->vm_flags |= VM_CAN_NONLINEAR;
1183         return 0;
1184 }