linux/fs/ceph/addr.c
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   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 absence 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
  57static inline struct ceph_snap_context *page_snap_context(struct page *page)
  58{
  59        if (PagePrivate(page))
  60                return (void *)page->private;
  61        return NULL;
  62}
  63
  64/*
  65 * Dirty a page.  Optimistically adjust accounting, on the assumption
  66 * that we won't race with invalidate.  If we do, readjust.
  67 */
  68static int ceph_set_page_dirty(struct page *page)
  69{
  70        struct address_space *mapping = page->mapping;
  71        struct inode *inode;
  72        struct ceph_inode_info *ci;
  73        int undo = 0;
  74        struct ceph_snap_context *snapc;
  75
  76        if (unlikely(!mapping))
  77                return !TestSetPageDirty(page);
  78
  79        if (TestSetPageDirty(page)) {
  80                dout("%p set_page_dirty %p idx %lu -- already dirty\n",
  81                     mapping->host, page, page->index);
  82                return 0;
  83        }
  84
  85        inode = mapping->host;
  86        ci = ceph_inode(inode);
  87
  88        /*
  89         * Note that we're grabbing a snapc ref here without holding
  90         * any locks!
  91         */
  92        snapc = ceph_get_snap_context(ci->i_snap_realm->cached_context);
  93
  94        /* dirty the head */
  95        spin_lock(&ci->i_ceph_lock);
  96        if (ci->i_head_snapc == NULL)
  97                ci->i_head_snapc = ceph_get_snap_context(snapc);
  98        ++ci->i_wrbuffer_ref_head;
  99        if (ci->i_wrbuffer_ref == 0)
 100                ihold(inode);
 101        ++ci->i_wrbuffer_ref;
 102        dout("%p set_page_dirty %p idx %lu head %d/%d -> %d/%d "
 103             "snapc %p seq %lld (%d snaps)\n",
 104             mapping->host, page, page->index,
 105             ci->i_wrbuffer_ref-1, ci->i_wrbuffer_ref_head-1,
 106             ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
 107             snapc, snapc->seq, snapc->num_snaps);
 108        spin_unlock(&ci->i_ceph_lock);
 109
 110        /* now adjust page */
 111        spin_lock_irq(&mapping->tree_lock);
 112        if (page->mapping) {    /* Race with truncate? */
 113                WARN_ON_ONCE(!PageUptodate(page));
 114                account_page_dirtied(page, page->mapping);
 115                radix_tree_tag_set(&mapping->page_tree,
 116                                page_index(page), PAGECACHE_TAG_DIRTY);
 117
 118                /*
 119                 * Reference snap context in page->private.  Also set
 120                 * PagePrivate so that we get invalidatepage callback.
 121                 */
 122                page->private = (unsigned long)snapc;
 123                SetPagePrivate(page);
 124        } else {
 125                dout("ANON set_page_dirty %p (raced truncate?)\n", page);
 126                undo = 1;
 127        }
 128
 129        spin_unlock_irq(&mapping->tree_lock);
 130
 131        if (undo)
 132                /* whoops, we failed to dirty the page */
 133                ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
 134
 135        __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
 136
 137        BUG_ON(!PageDirty(page));
 138        return 1;
 139}
 140
 141/*
 142 * If we are truncating the full page (i.e. offset == 0), adjust the
 143 * dirty page counters appropriately.  Only called if there is private
 144 * data on the page.
 145 */
 146static void ceph_invalidatepage(struct page *page, unsigned long offset)
 147{
 148        struct inode *inode;
 149        struct ceph_inode_info *ci;
 150        struct ceph_snap_context *snapc = page_snap_context(page);
 151
 152        BUG_ON(!PageLocked(page));
 153        BUG_ON(!PagePrivate(page));
 154        BUG_ON(!page->mapping);
 155
 156        inode = page->mapping->host;
 157
 158        /*
 159         * We can get non-dirty pages here due to races between
 160         * set_page_dirty and truncate_complete_page; just spit out a
 161         * warning, in case we end up with accounting problems later.
 162         */
 163        if (!PageDirty(page))
 164                pr_err("%p invalidatepage %p page not dirty\n", inode, page);
 165
 166        if (offset == 0)
 167                ClearPageChecked(page);
 168
 169        ci = ceph_inode(inode);
 170        if (offset == 0) {
 171                dout("%p invalidatepage %p idx %lu full dirty page %lu\n",
 172                     inode, page, page->index, offset);
 173                ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
 174                ceph_put_snap_context(snapc);
 175                page->private = 0;
 176                ClearPagePrivate(page);
 177        } else {
 178                dout("%p invalidatepage %p idx %lu partial dirty page\n",
 179                     inode, page, page->index);
 180        }
 181}
 182
 183/* just a sanity check */
 184static int ceph_releasepage(struct page *page, gfp_t g)
 185{
 186        struct inode *inode = page->mapping ? page->mapping->host : NULL;
 187        dout("%p releasepage %p idx %lu\n", inode, page, page->index);
 188        WARN_ON(PageDirty(page));
 189        WARN_ON(PagePrivate(page));
 190        return 0;
 191}
 192
 193/*
 194 * read a single page, without unlocking it.
 195 */
 196static int readpage_nounlock(struct file *filp, struct page *page)
 197{
 198        struct inode *inode = filp->f_dentry->d_inode;
 199        struct ceph_inode_info *ci = ceph_inode(inode);
 200        struct ceph_osd_client *osdc = 
 201                &ceph_inode_to_client(inode)->client->osdc;
 202        int err = 0;
 203        u64 len = PAGE_CACHE_SIZE;
 204
 205        dout("readpage inode %p file %p page %p index %lu\n",
 206             inode, filp, page, page->index);
 207        err = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
 208                                  (u64) page_offset(page), &len,
 209                                  ci->i_truncate_seq, ci->i_truncate_size,
 210                                  &page, 1, 0);
 211        if (err == -ENOENT)
 212                err = 0;
 213        if (err < 0) {
 214                SetPageError(page);
 215                goto out;
 216        } else if (err < PAGE_CACHE_SIZE) {
 217                /* zero fill remainder of page */
 218                zero_user_segment(page, err, PAGE_CACHE_SIZE);
 219        }
 220        SetPageUptodate(page);
 221
 222out:
 223        return err < 0 ? err : 0;
 224}
 225
 226static int ceph_readpage(struct file *filp, struct page *page)
 227{
 228        int r = readpage_nounlock(filp, page);
 229        unlock_page(page);
 230        return r;
 231}
 232
 233/*
 234 * Finish an async read(ahead) op.
 235 */
 236static void finish_read(struct ceph_osd_request *req, struct ceph_msg *msg)
 237{
 238        struct inode *inode = req->r_inode;
 239        struct ceph_osd_reply_head *replyhead;
 240        int rc, bytes;
 241        int i;
 242
 243        /* parse reply */
 244        replyhead = msg->front.iov_base;
 245        WARN_ON(le32_to_cpu(replyhead->num_ops) == 0);
 246        rc = le32_to_cpu(replyhead->result);
 247        bytes = le32_to_cpu(msg->hdr.data_len);
 248
 249        dout("finish_read %p req %p rc %d bytes %d\n", inode, req, rc, bytes);
 250
 251        /* unlock all pages, zeroing any data we didn't read */
 252        for (i = 0; i < req->r_num_pages; i++, bytes -= PAGE_CACHE_SIZE) {
 253                struct page *page = req->r_pages[i];
 254
 255                if (bytes < (int)PAGE_CACHE_SIZE) {
 256                        /* zero (remainder of) page */
 257                        int s = bytes < 0 ? 0 : bytes;
 258                        zero_user_segment(page, s, PAGE_CACHE_SIZE);
 259                }
 260                dout("finish_read %p uptodate %p idx %lu\n", inode, page,
 261                     page->index);
 262                flush_dcache_page(page);
 263                SetPageUptodate(page);
 264                unlock_page(page);
 265                page_cache_release(page);
 266        }
 267        kfree(req->r_pages);
 268}
 269
 270/*
 271 * start an async read(ahead) operation.  return nr_pages we submitted
 272 * a read for on success, or negative error code.
 273 */
 274static int start_read(struct inode *inode, struct list_head *page_list, int max)
 275{
 276        struct ceph_osd_client *osdc =
 277                &ceph_inode_to_client(inode)->client->osdc;
 278        struct ceph_inode_info *ci = ceph_inode(inode);
 279        struct page *page = list_entry(page_list->prev, struct page, lru);
 280        struct ceph_osd_request *req;
 281        u64 off;
 282        u64 len;
 283        int i;
 284        struct page **pages;
 285        pgoff_t next_index;
 286        int nr_pages = 0;
 287        int ret;
 288
 289        off = (u64) page_offset(page);
 290
 291        /* count pages */
 292        next_index = page->index;
 293        list_for_each_entry_reverse(page, page_list, lru) {
 294                if (page->index != next_index)
 295                        break;
 296                nr_pages++;
 297                next_index++;
 298                if (max && nr_pages == max)
 299                        break;
 300        }
 301        len = nr_pages << PAGE_CACHE_SHIFT;
 302        dout("start_read %p nr_pages %d is %lld~%lld\n", inode, nr_pages,
 303             off, len);
 304
 305        req = ceph_osdc_new_request(osdc, &ci->i_layout, ceph_vino(inode),
 306                                    off, &len,
 307                                    CEPH_OSD_OP_READ, CEPH_OSD_FLAG_READ,
 308                                    NULL, 0,
 309                                    ci->i_truncate_seq, ci->i_truncate_size,
 310                                    NULL, false, 1, 0);
 311        if (!req)
 312                return -ENOMEM;
 313
 314        /* build page vector */
 315        nr_pages = len >> PAGE_CACHE_SHIFT;
 316        pages = kmalloc(sizeof(*pages) * nr_pages, GFP_NOFS);
 317        ret = -ENOMEM;
 318        if (!pages)
 319                goto out;
 320        for (i = 0; i < nr_pages; ++i) {
 321                page = list_entry(page_list->prev, struct page, lru);
 322                BUG_ON(PageLocked(page));
 323                list_del(&page->lru);
 324                
 325                dout("start_read %p adding %p idx %lu\n", inode, page,
 326                     page->index);
 327                if (add_to_page_cache_lru(page, &inode->i_data, page->index,
 328                                          GFP_NOFS)) {
 329                        page_cache_release(page);
 330                        dout("start_read %p add_to_page_cache failed %p\n",
 331                             inode, page);
 332                        nr_pages = i;
 333                        goto out_pages;
 334                }
 335                pages[i] = page;
 336        }
 337        req->r_pages = pages;
 338        req->r_num_pages = nr_pages;
 339        req->r_callback = finish_read;
 340        req->r_inode = inode;
 341
 342        dout("start_read %p starting %p %lld~%lld\n", inode, req, off, len);
 343        ret = ceph_osdc_start_request(osdc, req, false);
 344        if (ret < 0)
 345                goto out_pages;
 346        ceph_osdc_put_request(req);
 347        return nr_pages;
 348
 349out_pages:
 350        ceph_release_page_vector(pages, nr_pages);
 351out:
 352        ceph_osdc_put_request(req);
 353        return ret;
 354}
 355
 356
 357/*
 358 * Read multiple pages.  Leave pages we don't read + unlock in page_list;
 359 * the caller (VM) cleans them up.
 360 */
 361static int ceph_readpages(struct file *file, struct address_space *mapping,
 362                          struct list_head *page_list, unsigned nr_pages)
 363{
 364        struct inode *inode = file->f_dentry->d_inode;
 365        struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 366        int rc = 0;
 367        int max = 0;
 368
 369        if (fsc->mount_options->rsize >= PAGE_CACHE_SIZE)
 370                max = (fsc->mount_options->rsize + PAGE_CACHE_SIZE - 1)
 371                        >> PAGE_SHIFT;
 372
 373        dout("readpages %p file %p nr_pages %d max %d\n", inode, file, nr_pages,
 374             max);
 375        while (!list_empty(page_list)) {
 376                rc = start_read(inode, page_list, max);
 377                if (rc < 0)
 378                        goto out;
 379                BUG_ON(rc == 0);
 380        }
 381out:
 382        dout("readpages %p file %p ret %d\n", inode, file, rc);
 383        return rc;
 384}
 385
 386/*
 387 * Get ref for the oldest snapc for an inode with dirty data... that is, the
 388 * only snap context we are allowed to write back.
 389 */
 390static struct ceph_snap_context *get_oldest_context(struct inode *inode,
 391                                                    u64 *snap_size)
 392{
 393        struct ceph_inode_info *ci = ceph_inode(inode);
 394        struct ceph_snap_context *snapc = NULL;
 395        struct ceph_cap_snap *capsnap = NULL;
 396
 397        spin_lock(&ci->i_ceph_lock);
 398        list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
 399                dout(" cap_snap %p snapc %p has %d dirty pages\n", capsnap,
 400                     capsnap->context, capsnap->dirty_pages);
 401                if (capsnap->dirty_pages) {
 402                        snapc = ceph_get_snap_context(capsnap->context);
 403                        if (snap_size)
 404                                *snap_size = capsnap->size;
 405                        break;
 406                }
 407        }
 408        if (!snapc && ci->i_wrbuffer_ref_head) {
 409                snapc = ceph_get_snap_context(ci->i_head_snapc);
 410                dout(" head snapc %p has %d dirty pages\n",
 411                     snapc, ci->i_wrbuffer_ref_head);
 412        }
 413        spin_unlock(&ci->i_ceph_lock);
 414        return snapc;
 415}
 416
 417/*
 418 * Write a single page, but leave the page locked.
 419 *
 420 * If we get a write error, set the page error bit, but still adjust the
 421 * dirty page accounting (i.e., page is no longer dirty).
 422 */
 423static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
 424{
 425        struct inode *inode;
 426        struct ceph_inode_info *ci;
 427        struct ceph_fs_client *fsc;
 428        struct ceph_osd_client *osdc;
 429        loff_t page_off = page_offset(page);
 430        int len = PAGE_CACHE_SIZE;
 431        loff_t i_size;
 432        int err = 0;
 433        struct ceph_snap_context *snapc, *oldest;
 434        u64 snap_size = 0;
 435        long writeback_stat;
 436
 437        dout("writepage %p idx %lu\n", page, page->index);
 438
 439        if (!page->mapping || !page->mapping->host) {
 440                dout("writepage %p - no mapping\n", page);
 441                return -EFAULT;
 442        }
 443        inode = page->mapping->host;
 444        ci = ceph_inode(inode);
 445        fsc = ceph_inode_to_client(inode);
 446        osdc = &fsc->client->osdc;
 447
 448        /* verify this is a writeable snap context */
 449        snapc = page_snap_context(page);
 450        if (snapc == NULL) {
 451                dout("writepage %p page %p not dirty?\n", inode, page);
 452                goto out;
 453        }
 454        oldest = get_oldest_context(inode, &snap_size);
 455        if (snapc->seq > oldest->seq) {
 456                dout("writepage %p page %p snapc %p not writeable - noop\n",
 457                     inode, page, snapc);
 458                /* we should only noop if called by kswapd */
 459                WARN_ON((current->flags & PF_MEMALLOC) == 0);
 460                ceph_put_snap_context(oldest);
 461                goto out;
 462        }
 463        ceph_put_snap_context(oldest);
 464
 465        /* is this a partial page at end of file? */
 466        if (snap_size)
 467                i_size = snap_size;
 468        else
 469                i_size = i_size_read(inode);
 470        if (i_size < page_off + len)
 471                len = i_size - page_off;
 472
 473        dout("writepage %p page %p index %lu on %llu~%u snapc %p\n",
 474             inode, page, page->index, page_off, len, snapc);
 475
 476        writeback_stat = atomic_long_inc_return(&fsc->writeback_count);
 477        if (writeback_stat >
 478            CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb))
 479                set_bdi_congested(&fsc->backing_dev_info, BLK_RW_ASYNC);
 480
 481        set_page_writeback(page);
 482        err = ceph_osdc_writepages(osdc, ceph_vino(inode),
 483                                   &ci->i_layout, snapc,
 484                                   page_off, len,
 485                                   ci->i_truncate_seq, ci->i_truncate_size,
 486                                   &inode->i_mtime,
 487                                   &page, 1, 0, 0, true);
 488        if (err < 0) {
 489                dout("writepage setting page/mapping error %d %p\n", err, page);
 490                SetPageError(page);
 491                mapping_set_error(&inode->i_data, err);
 492                if (wbc)
 493                        wbc->pages_skipped++;
 494        } else {
 495                dout("writepage cleaned page %p\n", page);
 496                err = 0;  /* vfs expects us to return 0 */
 497        }
 498        page->private = 0;
 499        ClearPagePrivate(page);
 500        end_page_writeback(page);
 501        ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
 502        ceph_put_snap_context(snapc);  /* page's reference */
 503out:
 504        return err;
 505}
 506
 507static int ceph_writepage(struct page *page, struct writeback_control *wbc)
 508{
 509        int err;
 510        struct inode *inode = page->mapping->host;
 511        BUG_ON(!inode);
 512        ihold(inode);
 513        err = writepage_nounlock(page, wbc);
 514        unlock_page(page);
 515        iput(inode);
 516        return err;
 517}
 518
 519
 520/*
 521 * lame release_pages helper.  release_pages() isn't exported to
 522 * modules.
 523 */
 524static void ceph_release_pages(struct page **pages, int num)
 525{
 526        struct pagevec pvec;
 527        int i;
 528
 529        pagevec_init(&pvec, 0);
 530        for (i = 0; i < num; i++) {
 531                if (pagevec_add(&pvec, pages[i]) == 0)
 532                        pagevec_release(&pvec);
 533        }
 534        pagevec_release(&pvec);
 535}
 536
 537
 538/*
 539 * async writeback completion handler.
 540 *
 541 * If we get an error, set the mapping error bit, but not the individual
 542 * page error bits.
 543 */
 544static void writepages_finish(struct ceph_osd_request *req,
 545                              struct ceph_msg *msg)
 546{
 547        struct inode *inode = req->r_inode;
 548        struct ceph_osd_reply_head *replyhead;
 549        struct ceph_osd_op *op;
 550        struct ceph_inode_info *ci = ceph_inode(inode);
 551        unsigned wrote;
 552        struct page *page;
 553        int i;
 554        struct ceph_snap_context *snapc = req->r_snapc;
 555        struct address_space *mapping = inode->i_mapping;
 556        __s32 rc = -EIO;
 557        u64 bytes = 0;
 558        struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 559        long writeback_stat;
 560        unsigned issued = ceph_caps_issued(ci);
 561
 562        /* parse reply */
 563        replyhead = msg->front.iov_base;
 564        WARN_ON(le32_to_cpu(replyhead->num_ops) == 0);
 565        op = (void *)(replyhead + 1);
 566        rc = le32_to_cpu(replyhead->result);
 567        bytes = le64_to_cpu(op->extent.length);
 568
 569        if (rc >= 0) {
 570                /*
 571                 * Assume we wrote the pages we originally sent.  The
 572                 * osd might reply with fewer pages if our writeback
 573                 * raced with a truncation and was adjusted at the osd,
 574                 * so don't believe the reply.
 575                 */
 576                wrote = req->r_num_pages;
 577        } else {
 578                wrote = 0;
 579                mapping_set_error(mapping, rc);
 580        }
 581        dout("writepages_finish %p rc %d bytes %llu wrote %d (pages)\n",
 582             inode, rc, bytes, wrote);
 583
 584        /* clean all pages */
 585        for (i = 0; i < req->r_num_pages; i++) {
 586                page = req->r_pages[i];
 587                BUG_ON(!page);
 588                WARN_ON(!PageUptodate(page));
 589
 590                writeback_stat =
 591                        atomic_long_dec_return(&fsc->writeback_count);
 592                if (writeback_stat <
 593                    CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
 594                        clear_bdi_congested(&fsc->backing_dev_info,
 595                                            BLK_RW_ASYNC);
 596
 597                ceph_put_snap_context(page_snap_context(page));
 598                page->private = 0;
 599                ClearPagePrivate(page);
 600                dout("unlocking %d %p\n", i, page);
 601                end_page_writeback(page);
 602
 603                /*
 604                 * We lost the cache cap, need to truncate the page before
 605                 * it is unlocked, otherwise we'd truncate it later in the
 606                 * page truncation thread, possibly losing some data that
 607                 * raced its way in
 608                 */
 609                if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0)
 610                        generic_error_remove_page(inode->i_mapping, page);
 611
 612                unlock_page(page);
 613        }
 614        dout("%p wrote+cleaned %d pages\n", inode, wrote);
 615        ceph_put_wrbuffer_cap_refs(ci, req->r_num_pages, snapc);
 616
 617        ceph_release_pages(req->r_pages, req->r_num_pages);
 618        if (req->r_pages_from_pool)
 619                mempool_free(req->r_pages,
 620                             ceph_sb_to_client(inode->i_sb)->wb_pagevec_pool);
 621        else
 622                kfree(req->r_pages);
 623        ceph_osdc_put_request(req);
 624}
 625
 626/*
 627 * allocate a page vec, either directly, or if necessary, via a the
 628 * mempool.  we avoid the mempool if we can because req->r_num_pages
 629 * may be less than the maximum write size.
 630 */
 631static void alloc_page_vec(struct ceph_fs_client *fsc,
 632                           struct ceph_osd_request *req)
 633{
 634        req->r_pages = kmalloc(sizeof(struct page *) * req->r_num_pages,
 635                               GFP_NOFS);
 636        if (!req->r_pages) {
 637                req->r_pages = mempool_alloc(fsc->wb_pagevec_pool, GFP_NOFS);
 638                req->r_pages_from_pool = 1;
 639                WARN_ON(!req->r_pages);
 640        }
 641}
 642
 643/*
 644 * initiate async writeback
 645 */
 646static int ceph_writepages_start(struct address_space *mapping,
 647                                 struct writeback_control *wbc)
 648{
 649        struct inode *inode = mapping->host;
 650        struct ceph_inode_info *ci = ceph_inode(inode);
 651        struct ceph_fs_client *fsc;
 652        pgoff_t index, start, end;
 653        int range_whole = 0;
 654        int should_loop = 1;
 655        pgoff_t max_pages = 0, max_pages_ever = 0;
 656        struct ceph_snap_context *snapc = NULL, *last_snapc = NULL, *pgsnapc;
 657        struct pagevec pvec;
 658        int done = 0;
 659        int rc = 0;
 660        unsigned wsize = 1 << inode->i_blkbits;
 661        struct ceph_osd_request *req = NULL;
 662        int do_sync;
 663        u64 snap_size = 0;
 664
 665        /*
 666         * Include a 'sync' in the OSD request if this is a data
 667         * integrity write (e.g., O_SYNC write or fsync()), or if our
 668         * cap is being revoked.
 669         */
 670        do_sync = wbc->sync_mode == WB_SYNC_ALL;
 671        if (ceph_caps_revoking(ci, CEPH_CAP_FILE_BUFFER))
 672                do_sync = 1;
 673        dout("writepages_start %p dosync=%d (mode=%s)\n",
 674             inode, do_sync,
 675             wbc->sync_mode == WB_SYNC_NONE ? "NONE" :
 676             (wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD"));
 677
 678        fsc = ceph_inode_to_client(inode);
 679        if (fsc->mount_state == CEPH_MOUNT_SHUTDOWN) {
 680                pr_warning("writepage_start %p on forced umount\n", inode);
 681                return -EIO; /* we're in a forced umount, don't write! */
 682        }
 683        if (fsc->mount_options->wsize && fsc->mount_options->wsize < wsize)
 684                wsize = fsc->mount_options->wsize;
 685        if (wsize < PAGE_CACHE_SIZE)
 686                wsize = PAGE_CACHE_SIZE;
 687        max_pages_ever = wsize >> PAGE_CACHE_SHIFT;
 688
 689        pagevec_init(&pvec, 0);
 690
 691        /* where to start/end? */
 692        if (wbc->range_cyclic) {
 693                start = mapping->writeback_index; /* Start from prev offset */
 694                end = -1;
 695                dout(" cyclic, start at %lu\n", start);
 696        } else {
 697                start = wbc->range_start >> PAGE_CACHE_SHIFT;
 698                end = wbc->range_end >> PAGE_CACHE_SHIFT;
 699                if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 700                        range_whole = 1;
 701                should_loop = 0;
 702                dout(" not cyclic, %lu to %lu\n", start, end);
 703        }
 704        index = start;
 705
 706retry:
 707        /* find oldest snap context with dirty data */
 708        ceph_put_snap_context(snapc);
 709        snapc = get_oldest_context(inode, &snap_size);
 710        if (!snapc) {
 711                /* hmm, why does writepages get called when there
 712                   is no dirty data? */
 713                dout(" no snap context with dirty data?\n");
 714                goto out;
 715        }
 716        dout(" oldest snapc is %p seq %lld (%d snaps)\n",
 717             snapc, snapc->seq, snapc->num_snaps);
 718        if (last_snapc && snapc != last_snapc) {
 719                /* if we switched to a newer snapc, restart our scan at the
 720                 * start of the original file range. */
 721                dout("  snapc differs from last pass, restarting at %lu\n",
 722                     index);
 723                index = start;
 724        }
 725        last_snapc = snapc;
 726
 727        while (!done && index <= end) {
 728                unsigned i;
 729                int first;
 730                pgoff_t next;
 731                int pvec_pages, locked_pages;
 732                struct page *page;
 733                int want;
 734                u64 offset, len;
 735                struct ceph_osd_request_head *reqhead;
 736                struct ceph_osd_op *op;
 737                long writeback_stat;
 738
 739                next = 0;
 740                locked_pages = 0;
 741                max_pages = max_pages_ever;
 742
 743get_more_pages:
 744                first = -1;
 745                want = min(end - index,
 746                           min((pgoff_t)PAGEVEC_SIZE,
 747                               max_pages - (pgoff_t)locked_pages) - 1)
 748                        + 1;
 749                pvec_pages = pagevec_lookup_tag(&pvec, mapping, &index,
 750                                                PAGECACHE_TAG_DIRTY,
 751                                                want);
 752                dout("pagevec_lookup_tag got %d\n", pvec_pages);
 753                if (!pvec_pages && !locked_pages)
 754                        break;
 755                for (i = 0; i < pvec_pages && locked_pages < max_pages; i++) {
 756                        page = pvec.pages[i];
 757                        dout("? %p idx %lu\n", page, page->index);
 758                        if (locked_pages == 0)
 759                                lock_page(page);  /* first page */
 760                        else if (!trylock_page(page))
 761                                break;
 762
 763                        /* only dirty pages, or our accounting breaks */
 764                        if (unlikely(!PageDirty(page)) ||
 765                            unlikely(page->mapping != mapping)) {
 766                                dout("!dirty or !mapping %p\n", page);
 767                                unlock_page(page);
 768                                break;
 769                        }
 770                        if (!wbc->range_cyclic && page->index > end) {
 771                                dout("end of range %p\n", page);
 772                                done = 1;
 773                                unlock_page(page);
 774                                break;
 775                        }
 776                        if (next && (page->index != next)) {
 777                                dout("not consecutive %p\n", page);
 778                                unlock_page(page);
 779                                break;
 780                        }
 781                        if (wbc->sync_mode != WB_SYNC_NONE) {
 782                                dout("waiting on writeback %p\n", page);
 783                                wait_on_page_writeback(page);
 784                        }
 785                        if ((snap_size && page_offset(page) > snap_size) ||
 786                            (!snap_size &&
 787                             page_offset(page) > i_size_read(inode))) {
 788                                dout("%p page eof %llu\n", page, snap_size ?
 789                                     snap_size : i_size_read(inode));
 790                                done = 1;
 791                                unlock_page(page);
 792                                break;
 793                        }
 794                        if (PageWriteback(page)) {
 795                                dout("%p under writeback\n", page);
 796                                unlock_page(page);
 797                                break;
 798                        }
 799
 800                        /* only if matching snap context */
 801                        pgsnapc = page_snap_context(page);
 802                        if (pgsnapc->seq > snapc->seq) {
 803                                dout("page snapc %p %lld > oldest %p %lld\n",
 804                                     pgsnapc, pgsnapc->seq, snapc, snapc->seq);
 805                                unlock_page(page);
 806                                if (!locked_pages)
 807                                        continue; /* keep looking for snap */
 808                                break;
 809                        }
 810
 811                        if (!clear_page_dirty_for_io(page)) {
 812                                dout("%p !clear_page_dirty_for_io\n", page);
 813                                unlock_page(page);
 814                                break;
 815                        }
 816
 817                        /* ok */
 818                        if (locked_pages == 0) {
 819                                /* prepare async write request */
 820                                offset = (u64) page_offset(page);
 821                                len = wsize;
 822                                req = ceph_osdc_new_request(&fsc->client->osdc,
 823                                            &ci->i_layout,
 824                                            ceph_vino(inode),
 825                                            offset, &len,
 826                                            CEPH_OSD_OP_WRITE,
 827                                            CEPH_OSD_FLAG_WRITE |
 828                                                    CEPH_OSD_FLAG_ONDISK,
 829                                            snapc, do_sync,
 830                                            ci->i_truncate_seq,
 831                                            ci->i_truncate_size,
 832                                            &inode->i_mtime, true, 1, 0);
 833
 834                                if (!req) {
 835                                        rc = -ENOMEM;
 836                                        unlock_page(page);
 837                                        break;
 838                                }
 839
 840                                max_pages = req->r_num_pages;
 841
 842                                alloc_page_vec(fsc, req);
 843                                req->r_callback = writepages_finish;
 844                                req->r_inode = inode;
 845                        }
 846
 847                        /* note position of first page in pvec */
 848                        if (first < 0)
 849                                first = i;
 850                        dout("%p will write page %p idx %lu\n",
 851                             inode, page, page->index);
 852
 853                        writeback_stat =
 854                               atomic_long_inc_return(&fsc->writeback_count);
 855                        if (writeback_stat > CONGESTION_ON_THRESH(
 856                                    fsc->mount_options->congestion_kb)) {
 857                                set_bdi_congested(&fsc->backing_dev_info,
 858                                                  BLK_RW_ASYNC);
 859                        }
 860
 861                        set_page_writeback(page);
 862                        req->r_pages[locked_pages] = page;
 863                        locked_pages++;
 864                        next = page->index + 1;
 865                }
 866
 867                /* did we get anything? */
 868                if (!locked_pages)
 869                        goto release_pvec_pages;
 870                if (i) {
 871                        int j;
 872                        BUG_ON(!locked_pages || first < 0);
 873
 874                        if (pvec_pages && i == pvec_pages &&
 875                            locked_pages < max_pages) {
 876                                dout("reached end pvec, trying for more\n");
 877                                pagevec_reinit(&pvec);
 878                                goto get_more_pages;
 879                        }
 880
 881                        /* shift unused pages over in the pvec...  we
 882                         * will need to release them below. */
 883                        for (j = i; j < pvec_pages; j++) {
 884                                dout(" pvec leftover page %p\n",
 885                                     pvec.pages[j]);
 886                                pvec.pages[j-i+first] = pvec.pages[j];
 887                        }
 888                        pvec.nr -= i-first;
 889                }
 890
 891                /* submit the write */
 892                offset = req->r_pages[0]->index << PAGE_CACHE_SHIFT;
 893                len = min((snap_size ? snap_size : i_size_read(inode)) - offset,
 894                          (u64)locked_pages << PAGE_CACHE_SHIFT);
 895                dout("writepages got %d pages at %llu~%llu\n",
 896                     locked_pages, offset, len);
 897
 898                /* revise final length, page count */
 899                req->r_num_pages = locked_pages;
 900                reqhead = req->r_request->front.iov_base;
 901                op = (void *)(reqhead + 1);
 902                op->extent.length = cpu_to_le64(len);
 903                op->payload_len = cpu_to_le32(len);
 904                req->r_request->hdr.data_len = cpu_to_le32(len);
 905
 906                rc = ceph_osdc_start_request(&fsc->client->osdc, req, true);
 907                BUG_ON(rc);
 908                req = NULL;
 909
 910                /* continue? */
 911                index = next;
 912                wbc->nr_to_write -= locked_pages;
 913                if (wbc->nr_to_write <= 0)
 914                        done = 1;
 915
 916release_pvec_pages:
 917                dout("pagevec_release on %d pages (%p)\n", (int)pvec.nr,
 918                     pvec.nr ? pvec.pages[0] : NULL);
 919                pagevec_release(&pvec);
 920
 921                if (locked_pages && !done)
 922                        goto retry;
 923        }
 924
 925        if (should_loop && !done) {
 926                /* more to do; loop back to beginning of file */
 927                dout("writepages looping back to beginning of file\n");
 928                should_loop = 0;
 929                index = 0;
 930                goto retry;
 931        }
 932
 933        if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 934                mapping->writeback_index = index;
 935
 936out:
 937        if (req)
 938                ceph_osdc_put_request(req);
 939        ceph_put_snap_context(snapc);
 940        dout("writepages done, rc = %d\n", rc);
 941        return rc;
 942}
 943
 944
 945
 946/*
 947 * See if a given @snapc is either writeable, or already written.
 948 */
 949static int context_is_writeable_or_written(struct inode *inode,
 950                                           struct ceph_snap_context *snapc)
 951{
 952        struct ceph_snap_context *oldest = get_oldest_context(inode, NULL);
 953        int ret = !oldest || snapc->seq <= oldest->seq;
 954
 955        ceph_put_snap_context(oldest);
 956        return ret;
 957}
 958
 959/*
 960 * We are only allowed to write into/dirty the page if the page is
 961 * clean, or already dirty within the same snap context.
 962 *
 963 * called with page locked.
 964 * return success with page locked,
 965 * or any failure (incl -EAGAIN) with page unlocked.
 966 */
 967static int ceph_update_writeable_page(struct file *file,
 968                            loff_t pos, unsigned len,
 969                            struct page *page)
 970{
 971        struct inode *inode = file->f_dentry->d_inode;
 972        struct ceph_inode_info *ci = ceph_inode(inode);
 973        struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
 974        loff_t page_off = pos & PAGE_CACHE_MASK;
 975        int pos_in_page = pos & ~PAGE_CACHE_MASK;
 976        int end_in_page = pos_in_page + len;
 977        loff_t i_size;
 978        int r;
 979        struct ceph_snap_context *snapc, *oldest;
 980
 981retry_locked:
 982        /* writepages currently holds page lock, but if we change that later, */
 983        wait_on_page_writeback(page);
 984
 985        /* check snap context */
 986        BUG_ON(!ci->i_snap_realm);
 987        down_read(&mdsc->snap_rwsem);
 988        BUG_ON(!ci->i_snap_realm->cached_context);
 989        snapc = page_snap_context(page);
 990        if (snapc && snapc != ci->i_head_snapc) {
 991                /*
 992                 * this page is already dirty in another (older) snap
 993                 * context!  is it writeable now?
 994                 */
 995                oldest = get_oldest_context(inode, NULL);
 996                up_read(&mdsc->snap_rwsem);
 997
 998                if (snapc->seq > oldest->seq) {
 999                        ceph_put_snap_context(oldest);
1000                        dout(" page %p snapc %p not current or oldest\n",
1001                             page, snapc);
1002                        /*
1003                         * queue for writeback, and wait for snapc to
1004                         * be writeable or written
1005                         */
1006                        snapc = ceph_get_snap_context(snapc);
1007                        unlock_page(page);
1008                        ceph_queue_writeback(inode);
1009                        r = wait_event_interruptible(ci->i_cap_wq,
1010                               context_is_writeable_or_written(inode, snapc));
1011                        ceph_put_snap_context(snapc);
1012                        if (r == -ERESTARTSYS)
1013                                return r;
1014                        return -EAGAIN;
1015                }
1016                ceph_put_snap_context(oldest);
1017
1018                /* yay, writeable, do it now (without dropping page lock) */
1019                dout(" page %p snapc %p not current, but oldest\n",
1020                     page, snapc);
1021                if (!clear_page_dirty_for_io(page))
1022                        goto retry_locked;
1023                r = writepage_nounlock(page, NULL);
1024                if (r < 0)
1025                        goto fail_nosnap;
1026                goto retry_locked;
1027        }
1028
1029        if (PageUptodate(page)) {
1030                dout(" page %p already uptodate\n", page);
1031                return 0;
1032        }
1033
1034        /* full page? */
1035        if (pos_in_page == 0 && len == PAGE_CACHE_SIZE)
1036                return 0;
1037
1038        /* past end of file? */
1039        i_size = inode->i_size;   /* caller holds i_mutex */
1040
1041        if (i_size + len > inode->i_sb->s_maxbytes) {
1042                /* file is too big */
1043                r = -EINVAL;
1044                goto fail;
1045        }
1046
1047        if (page_off >= i_size ||
1048            (pos_in_page == 0 && (pos+len) >= i_size &&
1049             end_in_page - pos_in_page != PAGE_CACHE_SIZE)) {
1050                dout(" zeroing %p 0 - %d and %d - %d\n",
1051                     page, pos_in_page, end_in_page, (int)PAGE_CACHE_SIZE);
1052                zero_user_segments(page,
1053                                   0, pos_in_page,
1054                                   end_in_page, PAGE_CACHE_SIZE);
1055                return 0;
1056        }
1057
1058        /* we need to read it. */
1059        up_read(&mdsc->snap_rwsem);
1060        r = readpage_nounlock(file, page);
1061        if (r < 0)
1062                goto fail_nosnap;
1063        goto retry_locked;
1064
1065fail:
1066        up_read(&mdsc->snap_rwsem);
1067fail_nosnap:
1068        unlock_page(page);
1069        return r;
1070}
1071
1072/*
1073 * We are only allowed to write into/dirty the page if the page is
1074 * clean, or already dirty within the same snap context.
1075 */
1076static int ceph_write_begin(struct file *file, struct address_space *mapping,
1077                            loff_t pos, unsigned len, unsigned flags,
1078                            struct page **pagep, void **fsdata)
1079{
1080        struct inode *inode = file->f_dentry->d_inode;
1081        struct page *page;
1082        pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1083        int r;
1084
1085        do {
1086                /* get a page */
1087                page = grab_cache_page_write_begin(mapping, index, 0);
1088                if (!page)
1089                        return -ENOMEM;
1090                *pagep = page;
1091
1092                dout("write_begin file %p inode %p page %p %d~%d\n", file,
1093                     inode, page, (int)pos, (int)len);
1094
1095                r = ceph_update_writeable_page(file, pos, len, page);
1096        } while (r == -EAGAIN);
1097
1098        return r;
1099}
1100
1101/*
1102 * we don't do anything in here that simple_write_end doesn't do
1103 * except adjust dirty page accounting and drop read lock on
1104 * mdsc->snap_rwsem.
1105 */
1106static int ceph_write_end(struct file *file, struct address_space *mapping,
1107                          loff_t pos, unsigned len, unsigned copied,
1108                          struct page *page, void *fsdata)
1109{
1110        struct inode *inode = file->f_dentry->d_inode;
1111        struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
1112        struct ceph_mds_client *mdsc = fsc->mdsc;
1113        unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1114        int check_cap = 0;
1115
1116        dout("write_end file %p inode %p page %p %d~%d (%d)\n", file,
1117             inode, page, (int)pos, (int)copied, (int)len);
1118
1119        /* zero the stale part of the page if we did a short copy */
1120        if (copied < len)
1121                zero_user_segment(page, from+copied, len);
1122
1123        /* did file size increase? */
1124        /* (no need for i_size_read(); we caller holds i_mutex */
1125        if (pos+copied > inode->i_size)
1126                check_cap = ceph_inode_set_size(inode, pos+copied);
1127
1128        if (!PageUptodate(page))
1129                SetPageUptodate(page);
1130
1131        set_page_dirty(page);
1132
1133        unlock_page(page);
1134        up_read(&mdsc->snap_rwsem);
1135        page_cache_release(page);
1136
1137        if (check_cap)
1138                ceph_check_caps(ceph_inode(inode), CHECK_CAPS_AUTHONLY, NULL);
1139
1140        return copied;
1141}
1142
1143/*
1144 * we set .direct_IO to indicate direct io is supported, but since we
1145 * intercept O_DIRECT reads and writes early, this function should
1146 * never get called.
1147 */
1148static ssize_t ceph_direct_io(int rw, struct kiocb *iocb,
1149                              const struct iovec *iov,
1150                              loff_t pos, unsigned long nr_segs)
1151{
1152        WARN_ON(1);
1153        return -EINVAL;
1154}
1155
1156const struct address_space_operations ceph_aops = {
1157        .readpage = ceph_readpage,
1158        .readpages = ceph_readpages,
1159        .writepage = ceph_writepage,
1160        .writepages = ceph_writepages_start,
1161        .write_begin = ceph_write_begin,
1162        .write_end = ceph_write_end,
1163        .set_page_dirty = ceph_set_page_dirty,
1164        .invalidatepage = ceph_invalidatepage,
1165        .releasepage = ceph_releasepage,
1166        .direct_IO = ceph_direct_io,
1167};
1168
1169
1170/*
1171 * vm ops
1172 */
1173
1174/*
1175 * Reuse write_begin here for simplicity.
1176 */
1177static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
1178{
1179        struct inode *inode = vma->vm_file->f_dentry->d_inode;
1180        struct page *page = vmf->page;
1181        struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
1182        loff_t off = page_offset(page);
1183        loff_t size, len;
1184        int ret;
1185
1186        /* Update time before taking page lock */
1187        file_update_time(vma->vm_file);
1188
1189        size = i_size_read(inode);
1190        if (off + PAGE_CACHE_SIZE <= size)
1191                len = PAGE_CACHE_SIZE;
1192        else
1193                len = size & ~PAGE_CACHE_MASK;
1194
1195        dout("page_mkwrite %p %llu~%llu page %p idx %lu\n", inode,
1196             off, len, page, page->index);
1197
1198        lock_page(page);
1199
1200        ret = VM_FAULT_NOPAGE;
1201        if ((off > size) ||
1202            (page->mapping != inode->i_mapping))
1203                goto out;
1204
1205        ret = ceph_update_writeable_page(vma->vm_file, off, len, page);
1206        if (ret == 0) {
1207                /* success.  we'll keep the page locked. */
1208                set_page_dirty(page);
1209                up_read(&mdsc->snap_rwsem);
1210                ret = VM_FAULT_LOCKED;
1211        } else {
1212                if (ret == -ENOMEM)
1213                        ret = VM_FAULT_OOM;
1214                else
1215                        ret = VM_FAULT_SIGBUS;
1216        }
1217out:
1218        dout("page_mkwrite %p %llu~%llu = %d\n", inode, off, len, ret);
1219        if (ret != VM_FAULT_LOCKED)
1220                unlock_page(page);
1221        return ret;
1222}
1223
1224static struct vm_operations_struct ceph_vmops = {
1225        .fault          = filemap_fault,
1226        .page_mkwrite   = ceph_page_mkwrite,
1227};
1228
1229int ceph_mmap(struct file *file, struct vm_area_struct *vma)
1230{
1231        struct address_space *mapping = file->f_mapping;
1232
1233        if (!mapping->a_ops->readpage)
1234                return -ENOEXEC;
1235        file_accessed(file);
1236        vma->vm_ops = &ceph_vmops;
1237        vma->vm_flags |= VM_CAN_NONLINEAR;
1238        return 0;
1239}
1240
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