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