Merge branch 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelv...
[linux-2.6.git] / fs / ceph / addr.c
1 #include "ceph_debug.h"
2
3 #include <linux/backing-dev.h>
4 #include <linux/fs.h>
5 #include <linux/mm.h>
6 #include <linux/pagemap.h>
7 #include <linux/writeback.h>    /* generic_writepages */
8 #include <linux/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;
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         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 */
184 static 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(page->private);
190         WARN_ON(PagePrivate(page));
191         return 0;
192 }
193
194 /*
195  * read a single page, without unlocking it.
196  */
197 static int readpage_nounlock(struct file *filp, struct page *page)
198 {
199         struct inode *inode = filp->f_dentry->d_inode;
200         struct ceph_inode_info *ci = ceph_inode(inode);
201         struct ceph_osd_client *osdc = &ceph_inode_to_client(inode)->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                                   page->index << PAGE_CACHE_SHIFT, &len,
209                                   ci->i_truncate_seq, ci->i_truncate_size,
210                                   &page, 1);
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
222 out:
223         return err < 0 ? err : 0;
224 }
225
226 static 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  * Build a vector of contiguous pages from the provided page list.
235  */
236 static struct page **page_vector_from_list(struct list_head *page_list,
237                                            unsigned *nr_pages)
238 {
239         struct page **pages;
240         struct page *page;
241         int next_index, contig_pages = 0;
242
243         /* build page vector */
244         pages = kmalloc(sizeof(*pages) * *nr_pages, GFP_NOFS);
245         if (!pages)
246                 return ERR_PTR(-ENOMEM);
247
248         BUG_ON(list_empty(page_list));
249         next_index = list_entry(page_list->prev, struct page, lru)->index;
250         list_for_each_entry_reverse(page, page_list, lru) {
251                 if (page->index == next_index) {
252                         dout("readpages page %d %p\n", contig_pages, page);
253                         pages[contig_pages] = page;
254                         contig_pages++;
255                         next_index++;
256                 } else {
257                         break;
258                 }
259         }
260         *nr_pages = contig_pages;
261         return pages;
262 }
263
264 /*
265  * Read multiple pages.  Leave pages we don't read + unlock in page_list;
266  * the caller (VM) cleans them up.
267  */
268 static int ceph_readpages(struct file *file, struct address_space *mapping,
269                           struct list_head *page_list, unsigned nr_pages)
270 {
271         struct inode *inode = file->f_dentry->d_inode;
272         struct ceph_inode_info *ci = ceph_inode(inode);
273         struct ceph_osd_client *osdc = &ceph_inode_to_client(inode)->osdc;
274         int rc = 0;
275         struct page **pages;
276         struct pagevec pvec;
277         loff_t offset;
278         u64 len;
279
280         dout("readpages %p file %p nr_pages %d\n",
281              inode, file, nr_pages);
282
283         pages = page_vector_from_list(page_list, &nr_pages);
284         if (IS_ERR(pages))
285                 return PTR_ERR(pages);
286
287         /* guess read extent */
288         offset = pages[0]->index << PAGE_CACHE_SHIFT;
289         len = nr_pages << PAGE_CACHE_SHIFT;
290         rc = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
291                                  offset, &len,
292                                  ci->i_truncate_seq, ci->i_truncate_size,
293                                  pages, nr_pages);
294         if (rc == -ENOENT)
295                 rc = 0;
296         if (rc < 0)
297                 goto out;
298
299         /* set uptodate and add to lru in pagevec-sized chunks */
300         pagevec_init(&pvec, 0);
301         for (; !list_empty(page_list) && len > 0;
302              rc -= PAGE_CACHE_SIZE, len -= PAGE_CACHE_SIZE) {
303                 struct page *page =
304                         list_entry(page_list->prev, struct page, lru);
305
306                 list_del(&page->lru);
307
308                 if (rc < (int)PAGE_CACHE_SIZE) {
309                         /* zero (remainder of) page */
310                         int s = rc < 0 ? 0 : rc;
311                         zero_user_segment(page, s, PAGE_CACHE_SIZE);
312                 }
313
314                 if (add_to_page_cache(page, mapping, page->index, GFP_NOFS)) {
315                         page_cache_release(page);
316                         dout("readpages %p add_to_page_cache failed %p\n",
317                              inode, page);
318                         continue;
319                 }
320                 dout("readpages %p adding %p idx %lu\n", inode, page,
321                      page->index);
322                 flush_dcache_page(page);
323                 SetPageUptodate(page);
324                 unlock_page(page);
325                 if (pagevec_add(&pvec, page) == 0)
326                         pagevec_lru_add_file(&pvec);   /* add to lru */
327         }
328         pagevec_lru_add_file(&pvec);
329         rc = 0;
330
331 out:
332         kfree(pages);
333         return rc;
334 }
335
336 /*
337  * Get ref for the oldest snapc for an inode with dirty data... that is, the
338  * only snap context we are allowed to write back.
339  *
340  * Caller holds i_lock.
341  */
342 static struct ceph_snap_context *__get_oldest_context(struct inode *inode,
343                                                       u64 *snap_size)
344 {
345         struct ceph_inode_info *ci = ceph_inode(inode);
346         struct ceph_snap_context *snapc = NULL;
347         struct ceph_cap_snap *capsnap = NULL;
348
349         list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
350                 dout(" cap_snap %p snapc %p has %d dirty pages\n", capsnap,
351                      capsnap->context, capsnap->dirty_pages);
352                 if (capsnap->dirty_pages) {
353                         snapc = ceph_get_snap_context(capsnap->context);
354                         if (snap_size)
355                                 *snap_size = capsnap->size;
356                         break;
357                 }
358         }
359         if (!snapc && ci->i_snap_realm) {
360                 snapc = ceph_get_snap_context(ci->i_snap_realm->cached_context);
361                 dout(" head snapc %p has %d dirty pages\n",
362                      snapc, ci->i_wrbuffer_ref_head);
363         }
364         return snapc;
365 }
366
367 static struct ceph_snap_context *get_oldest_context(struct inode *inode,
368                                                     u64 *snap_size)
369 {
370         struct ceph_snap_context *snapc = NULL;
371
372         spin_lock(&inode->i_lock);
373         snapc = __get_oldest_context(inode, snap_size);
374         spin_unlock(&inode->i_lock);
375         return snapc;
376 }
377
378 /*
379  * Write a single page, but leave the page locked.
380  *
381  * If we get a write error, set the page error bit, but still adjust the
382  * dirty page accounting (i.e., page is no longer dirty).
383  */
384 static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
385 {
386         struct inode *inode;
387         struct ceph_inode_info *ci;
388         struct ceph_client *client;
389         struct ceph_osd_client *osdc;
390         loff_t page_off = page->index << PAGE_CACHE_SHIFT;
391         int len = PAGE_CACHE_SIZE;
392         loff_t i_size;
393         int err = 0;
394         struct ceph_snap_context *snapc;
395         u64 snap_size = 0;
396         long writeback_stat;
397
398         dout("writepage %p idx %lu\n", page, page->index);
399
400         if (!page->mapping || !page->mapping->host) {
401                 dout("writepage %p - no mapping\n", page);
402                 return -EFAULT;
403         }
404         inode = page->mapping->host;
405         ci = ceph_inode(inode);
406         client = ceph_inode_to_client(inode);
407         osdc = &client->osdc;
408
409         /* verify this is a writeable snap context */
410         snapc = (void *)page->private;
411         if (snapc == NULL) {
412                 dout("writepage %p page %p not dirty?\n", inode, page);
413                 goto out;
414         }
415         if (snapc != get_oldest_context(inode, &snap_size)) {
416                 dout("writepage %p page %p snapc %p not writeable - noop\n",
417                      inode, page, (void *)page->private);
418                 /* we should only noop if called by kswapd */
419                 WARN_ON((current->flags & PF_MEMALLOC) == 0);
420                 goto out;
421         }
422
423         /* is this a partial page at end of file? */
424         if (snap_size)
425                 i_size = snap_size;
426         else
427                 i_size = i_size_read(inode);
428         if (i_size < page_off + len)
429                 len = i_size - page_off;
430
431         dout("writepage %p page %p index %lu on %llu~%u\n",
432              inode, page, page->index, page_off, len);
433
434         writeback_stat = atomic_long_inc_return(&client->writeback_count);
435         if (writeback_stat >
436             CONGESTION_ON_THRESH(client->mount_args->congestion_kb))
437                 set_bdi_congested(&client->backing_dev_info, BLK_RW_ASYNC);
438
439         set_page_writeback(page);
440         err = ceph_osdc_writepages(osdc, ceph_vino(inode),
441                                    &ci->i_layout, snapc,
442                                    page_off, len,
443                                    ci->i_truncate_seq, ci->i_truncate_size,
444                                    &inode->i_mtime,
445                                    &page, 1, 0, 0, true);
446         if (err < 0) {
447                 dout("writepage setting page/mapping error %d %p\n", err, page);
448                 SetPageError(page);
449                 mapping_set_error(&inode->i_data, err);
450                 if (wbc)
451                         wbc->pages_skipped++;
452         } else {
453                 dout("writepage cleaned page %p\n", page);
454                 err = 0;  /* vfs expects us to return 0 */
455         }
456         page->private = 0;
457         ClearPagePrivate(page);
458         end_page_writeback(page);
459         ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
460         ceph_put_snap_context(snapc);
461 out:
462         return err;
463 }
464
465 static int ceph_writepage(struct page *page, struct writeback_control *wbc)
466 {
467         int err;
468         struct inode *inode = page->mapping->host;
469         BUG_ON(!inode);
470         igrab(inode);
471         err = writepage_nounlock(page, wbc);
472         unlock_page(page);
473         iput(inode);
474         return err;
475 }
476
477
478 /*
479  * lame release_pages helper.  release_pages() isn't exported to
480  * modules.
481  */
482 static void ceph_release_pages(struct page **pages, int num)
483 {
484         struct pagevec pvec;
485         int i;
486
487         pagevec_init(&pvec, 0);
488         for (i = 0; i < num; i++) {
489                 if (pagevec_add(&pvec, pages[i]) == 0)
490                         pagevec_release(&pvec);
491         }
492         pagevec_release(&pvec);
493 }
494
495
496 /*
497  * async writeback completion handler.
498  *
499  * If we get an error, set the mapping error bit, but not the individual
500  * page error bits.
501  */
502 static void writepages_finish(struct ceph_osd_request *req,
503                               struct ceph_msg *msg)
504 {
505         struct inode *inode = req->r_inode;
506         struct ceph_osd_reply_head *replyhead;
507         struct ceph_osd_op *op;
508         struct ceph_inode_info *ci = ceph_inode(inode);
509         unsigned wrote;
510         struct page *page;
511         int i;
512         struct ceph_snap_context *snapc = req->r_snapc;
513         struct address_space *mapping = inode->i_mapping;
514         struct writeback_control *wbc = req->r_wbc;
515         __s32 rc = -EIO;
516         u64 bytes = 0;
517         struct ceph_client *client = ceph_inode_to_client(inode);
518         long writeback_stat;
519         unsigned issued = __ceph_caps_issued(ci, NULL);
520
521         /* parse reply */
522         replyhead = msg->front.iov_base;
523         WARN_ON(le32_to_cpu(replyhead->num_ops) == 0);
524         op = (void *)(replyhead + 1);
525         rc = le32_to_cpu(replyhead->result);
526         bytes = le64_to_cpu(op->extent.length);
527
528         if (rc >= 0) {
529                 /*
530                  * Assume we wrote the pages we originally sent.  The
531                  * osd might reply with fewer pages if our writeback
532                  * raced with a truncation and was adjusted at the osd,
533                  * so don't believe the reply.
534                  */
535                 wrote = req->r_num_pages;
536         } else {
537                 wrote = 0;
538                 mapping_set_error(mapping, rc);
539         }
540         dout("writepages_finish %p rc %d bytes %llu wrote %d (pages)\n",
541              inode, rc, bytes, wrote);
542
543         /* clean all pages */
544         for (i = 0; i < req->r_num_pages; i++) {
545                 page = req->r_pages[i];
546                 BUG_ON(!page);
547                 WARN_ON(!PageUptodate(page));
548
549                 writeback_stat =
550                         atomic_long_dec_return(&client->writeback_count);
551                 if (writeback_stat <
552                     CONGESTION_OFF_THRESH(client->mount_args->congestion_kb))
553                         clear_bdi_congested(&client->backing_dev_info,
554                                             BLK_RW_ASYNC);
555
556                 if (i >= wrote) {
557                         dout("inode %p skipping page %p\n", inode, page);
558                         wbc->pages_skipped++;
559                 }
560                 page->private = 0;
561                 ClearPagePrivate(page);
562                 ceph_put_snap_context(snapc);
563                 dout("unlocking %d %p\n", i, page);
564                 end_page_writeback(page);
565
566                 /*
567                  * We lost the cache cap, need to truncate the page before
568                  * it is unlocked, otherwise we'd truncate it later in the
569                  * page truncation thread, possibly losing some data that
570                  * raced its way in
571                  */
572                 if ((issued & CEPH_CAP_FILE_CACHE) == 0)
573                         generic_error_remove_page(inode->i_mapping, page);
574
575                 unlock_page(page);
576         }
577         dout("%p wrote+cleaned %d pages\n", inode, wrote);
578         ceph_put_wrbuffer_cap_refs(ci, req->r_num_pages, snapc);
579
580         ceph_release_pages(req->r_pages, req->r_num_pages);
581         if (req->r_pages_from_pool)
582                 mempool_free(req->r_pages,
583                              ceph_client(inode->i_sb)->wb_pagevec_pool);
584         else
585                 kfree(req->r_pages);
586         ceph_osdc_put_request(req);
587 }
588
589 /*
590  * allocate a page vec, either directly, or if necessary, via a the
591  * mempool.  we avoid the mempool if we can because req->r_num_pages
592  * may be less than the maximum write size.
593  */
594 static void alloc_page_vec(struct ceph_client *client,
595                            struct ceph_osd_request *req)
596 {
597         req->r_pages = kmalloc(sizeof(struct page *) * req->r_num_pages,
598                                GFP_NOFS);
599         if (!req->r_pages) {
600                 req->r_pages = mempool_alloc(client->wb_pagevec_pool, GFP_NOFS);
601                 req->r_pages_from_pool = 1;
602                 WARN_ON(!req->r_pages);
603         }
604 }
605
606 /*
607  * initiate async writeback
608  */
609 static int ceph_writepages_start(struct address_space *mapping,
610                                  struct writeback_control *wbc)
611 {
612         struct inode *inode = mapping->host;
613         struct backing_dev_info *bdi = mapping->backing_dev_info;
614         struct ceph_inode_info *ci = ceph_inode(inode);
615         struct ceph_client *client;
616         pgoff_t index, start, end;
617         int range_whole = 0;
618         int should_loop = 1;
619         pgoff_t max_pages = 0, max_pages_ever = 0;
620         struct ceph_snap_context *snapc = NULL, *last_snapc = NULL;
621         struct pagevec pvec;
622         int done = 0;
623         int rc = 0;
624         unsigned wsize = 1 << inode->i_blkbits;
625         struct ceph_osd_request *req = NULL;
626         int do_sync;
627         u64 snap_size = 0;
628
629         /*
630          * Include a 'sync' in the OSD request if this is a data
631          * integrity write (e.g., O_SYNC write or fsync()), or if our
632          * cap is being revoked.
633          */
634         do_sync = wbc->sync_mode == WB_SYNC_ALL;
635         if (ceph_caps_revoking(ci, CEPH_CAP_FILE_BUFFER))
636                 do_sync = 1;
637         dout("writepages_start %p dosync=%d (mode=%s)\n",
638              inode, do_sync,
639              wbc->sync_mode == WB_SYNC_NONE ? "NONE" :
640              (wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD"));
641
642         client = ceph_inode_to_client(inode);
643         if (client->mount_state == CEPH_MOUNT_SHUTDOWN) {
644                 pr_warning("writepage_start %p on forced umount\n", inode);
645                 return -EIO; /* we're in a forced umount, don't write! */
646         }
647         if (client->mount_args->wsize && client->mount_args->wsize < wsize)
648                 wsize = client->mount_args->wsize;
649         if (wsize < PAGE_CACHE_SIZE)
650                 wsize = PAGE_CACHE_SIZE;
651         max_pages_ever = wsize >> PAGE_CACHE_SHIFT;
652
653         pagevec_init(&pvec, 0);
654
655         /* ?? */
656         if (wbc->nonblocking && bdi_write_congested(bdi)) {
657                 dout(" writepages congested\n");
658                 wbc->encountered_congestion = 1;
659                 goto out_final;
660         }
661
662         /* where to start/end? */
663         if (wbc->range_cyclic) {
664                 start = mapping->writeback_index; /* Start from prev offset */
665                 end = -1;
666                 dout(" cyclic, start at %lu\n", start);
667         } else {
668                 start = wbc->range_start >> PAGE_CACHE_SHIFT;
669                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
670                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
671                         range_whole = 1;
672                 should_loop = 0;
673                 dout(" not cyclic, %lu to %lu\n", start, end);
674         }
675         index = start;
676
677 retry:
678         /* find oldest snap context with dirty data */
679         ceph_put_snap_context(snapc);
680         snapc = get_oldest_context(inode, &snap_size);
681         if (!snapc) {
682                 /* hmm, why does writepages get called when there
683                    is no dirty data? */
684                 dout(" no snap context with dirty data?\n");
685                 goto out;
686         }
687         dout(" oldest snapc is %p seq %lld (%d snaps)\n",
688              snapc, snapc->seq, snapc->num_snaps);
689         if (last_snapc && snapc != last_snapc) {
690                 /* if we switched to a newer snapc, restart our scan at the
691                  * start of the original file range. */
692                 dout("  snapc differs from last pass, restarting at %lu\n",
693                      index);
694                 index = start;
695         }
696         last_snapc = snapc;
697
698         while (!done && index <= end) {
699                 unsigned i;
700                 int first;
701                 pgoff_t next;
702                 int pvec_pages, locked_pages;
703                 struct page *page;
704                 int want;
705                 u64 offset, len;
706                 struct ceph_osd_request_head *reqhead;
707                 struct ceph_osd_op *op;
708                 long writeback_stat;
709
710                 next = 0;
711                 locked_pages = 0;
712                 max_pages = max_pages_ever;
713
714 get_more_pages:
715                 first = -1;
716                 want = min(end - index,
717                            min((pgoff_t)PAGEVEC_SIZE,
718                                max_pages - (pgoff_t)locked_pages) - 1)
719                         + 1;
720                 pvec_pages = pagevec_lookup_tag(&pvec, mapping, &index,
721                                                 PAGECACHE_TAG_DIRTY,
722                                                 want);
723                 dout("pagevec_lookup_tag got %d\n", pvec_pages);
724                 if (!pvec_pages && !locked_pages)
725                         break;
726                 for (i = 0; i < pvec_pages && locked_pages < max_pages; i++) {
727                         page = pvec.pages[i];
728                         dout("? %p idx %lu\n", page, page->index);
729                         if (locked_pages == 0)
730                                 lock_page(page);  /* first page */
731                         else if (!trylock_page(page))
732                                 break;
733
734                         /* only dirty pages, or our accounting breaks */
735                         if (unlikely(!PageDirty(page)) ||
736                             unlikely(page->mapping != mapping)) {
737                                 dout("!dirty or !mapping %p\n", page);
738                                 unlock_page(page);
739                                 break;
740                         }
741                         if (!wbc->range_cyclic && page->index > end) {
742                                 dout("end of range %p\n", page);
743                                 done = 1;
744                                 unlock_page(page);
745                                 break;
746                         }
747                         if (next && (page->index != next)) {
748                                 dout("not consecutive %p\n", page);
749                                 unlock_page(page);
750                                 break;
751                         }
752                         if (wbc->sync_mode != WB_SYNC_NONE) {
753                                 dout("waiting on writeback %p\n", page);
754                                 wait_on_page_writeback(page);
755                         }
756                         if ((snap_size && page_offset(page) > snap_size) ||
757                             (!snap_size &&
758                              page_offset(page) > i_size_read(inode))) {
759                                 dout("%p page eof %llu\n", page, snap_size ?
760                                      snap_size : i_size_read(inode));
761                                 done = 1;
762                                 unlock_page(page);
763                                 break;
764                         }
765                         if (PageWriteback(page)) {
766                                 dout("%p under writeback\n", page);
767                                 unlock_page(page);
768                                 break;
769                         }
770
771                         /* only if matching snap context */
772                         if (snapc != (void *)page->private) {
773                                 dout("page snapc %p != oldest %p\n",
774                                      (void *)page->private, snapc);
775                                 unlock_page(page);
776                                 if (!locked_pages)
777                                         continue; /* keep looking for snap */
778                                 break;
779                         }
780
781                         if (!clear_page_dirty_for_io(page)) {
782                                 dout("%p !clear_page_dirty_for_io\n", page);
783                                 unlock_page(page);
784                                 break;
785                         }
786
787                         /* ok */
788                         if (locked_pages == 0) {
789                                 /* prepare async write request */
790                                 offset = page->index << PAGE_CACHE_SHIFT;
791                                 len = wsize;
792                                 req = ceph_osdc_new_request(&client->osdc,
793                                             &ci->i_layout,
794                                             ceph_vino(inode),
795                                             offset, &len,
796                                             CEPH_OSD_OP_WRITE,
797                                             CEPH_OSD_FLAG_WRITE |
798                                                     CEPH_OSD_FLAG_ONDISK,
799                                             snapc, do_sync,
800                                             ci->i_truncate_seq,
801                                             ci->i_truncate_size,
802                                             &inode->i_mtime, true, 1);
803                                 max_pages = req->r_num_pages;
804
805                                 alloc_page_vec(client, req);
806                                 req->r_callback = writepages_finish;
807                                 req->r_inode = inode;
808                                 req->r_wbc = wbc;
809                         }
810
811                         /* note position of first page in pvec */
812                         if (first < 0)
813                                 first = i;
814                         dout("%p will write page %p idx %lu\n",
815                              inode, page, page->index);
816
817                         writeback_stat = atomic_long_inc_return(&client->writeback_count);
818                         if (writeback_stat > CONGESTION_ON_THRESH(client->mount_args->congestion_kb)) {
819                                 set_bdi_congested(&client->backing_dev_info, BLK_RW_ASYNC);
820                         }
821
822                         set_page_writeback(page);
823                         req->r_pages[locked_pages] = page;
824                         locked_pages++;
825                         next = page->index + 1;
826                 }
827
828                 /* did we get anything? */
829                 if (!locked_pages)
830                         goto release_pvec_pages;
831                 if (i) {
832                         int j;
833                         BUG_ON(!locked_pages || first < 0);
834
835                         if (pvec_pages && i == pvec_pages &&
836                             locked_pages < max_pages) {
837                                 dout("reached end pvec, trying for more\n");
838                                 pagevec_reinit(&pvec);
839                                 goto get_more_pages;
840                         }
841
842                         /* shift unused pages over in the pvec...  we
843                          * will need to release them below. */
844                         for (j = i; j < pvec_pages; j++) {
845                                 dout(" pvec leftover page %p\n",
846                                      pvec.pages[j]);
847                                 pvec.pages[j-i+first] = pvec.pages[j];
848                         }
849                         pvec.nr -= i-first;
850                 }
851
852                 /* submit the write */
853                 offset = req->r_pages[0]->index << PAGE_CACHE_SHIFT;
854                 len = min((snap_size ? snap_size : i_size_read(inode)) - offset,
855                           (u64)locked_pages << PAGE_CACHE_SHIFT);
856                 dout("writepages got %d pages at %llu~%llu\n",
857                      locked_pages, offset, len);
858
859                 /* revise final length, page count */
860                 req->r_num_pages = locked_pages;
861                 reqhead = req->r_request->front.iov_base;
862                 op = (void *)(reqhead + 1);
863                 op->extent.length = cpu_to_le64(len);
864                 op->payload_len = cpu_to_le32(len);
865                 req->r_request->hdr.data_len = cpu_to_le32(len);
866
867                 ceph_osdc_start_request(&client->osdc, req, true);
868                 req = NULL;
869
870                 /* continue? */
871                 index = next;
872                 wbc->nr_to_write -= locked_pages;
873                 if (wbc->nr_to_write <= 0)
874                         done = 1;
875
876 release_pvec_pages:
877                 dout("pagevec_release on %d pages (%p)\n", (int)pvec.nr,
878                      pvec.nr ? pvec.pages[0] : NULL);
879                 pagevec_release(&pvec);
880
881                 if (locked_pages && !done)
882                         goto retry;
883         }
884
885         if (should_loop && !done) {
886                 /* more to do; loop back to beginning of file */
887                 dout("writepages looping back to beginning of file\n");
888                 should_loop = 0;
889                 index = 0;
890                 goto retry;
891         }
892
893         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
894                 mapping->writeback_index = index;
895
896 out:
897         if (req)
898                 ceph_osdc_put_request(req);
899         if (rc > 0)
900                 rc = 0;  /* vfs expects us to return 0 */
901         ceph_put_snap_context(snapc);
902         dout("writepages done, rc = %d\n", rc);
903 out_final:
904         return rc;
905 }
906
907
908
909 /*
910  * See if a given @snapc is either writeable, or already written.
911  */
912 static int context_is_writeable_or_written(struct inode *inode,
913                                            struct ceph_snap_context *snapc)
914 {
915         struct ceph_snap_context *oldest = get_oldest_context(inode, NULL);
916         return !oldest || snapc->seq <= oldest->seq;
917 }
918
919 /*
920  * We are only allowed to write into/dirty the page if the page is
921  * clean, or already dirty within the same snap context.
922  */
923 static int ceph_update_writeable_page(struct file *file,
924                             loff_t pos, unsigned len,
925                             struct page *page)
926 {
927         struct inode *inode = file->f_dentry->d_inode;
928         struct ceph_inode_info *ci = ceph_inode(inode);
929         struct ceph_mds_client *mdsc = &ceph_inode_to_client(inode)->mdsc;
930         loff_t page_off = pos & PAGE_CACHE_MASK;
931         int pos_in_page = pos & ~PAGE_CACHE_MASK;
932         int end_in_page = pos_in_page + len;
933         loff_t i_size;
934         struct ceph_snap_context *snapc;
935         int r;
936
937 retry_locked:
938         /* writepages currently holds page lock, but if we change that later, */
939         wait_on_page_writeback(page);
940
941         /* check snap context */
942         BUG_ON(!ci->i_snap_realm);
943         down_read(&mdsc->snap_rwsem);
944         BUG_ON(!ci->i_snap_realm->cached_context);
945         if (page->private &&
946             (void *)page->private != ci->i_snap_realm->cached_context) {
947                 /*
948                  * this page is already dirty in another (older) snap
949                  * context!  is it writeable now?
950                  */
951                 snapc = get_oldest_context(inode, NULL);
952                 up_read(&mdsc->snap_rwsem);
953
954                 if (snapc != (void *)page->private) {
955                         dout(" page %p snapc %p not current or oldest\n",
956                              page, (void *)page->private);
957                         /*
958                          * queue for writeback, and wait for snapc to
959                          * be writeable or written
960                          */
961                         snapc = ceph_get_snap_context((void *)page->private);
962                         unlock_page(page);
963                         ceph_queue_writeback(inode);
964                         wait_event_interruptible(ci->i_cap_wq,
965                                context_is_writeable_or_written(inode, snapc));
966                         ceph_put_snap_context(snapc);
967                         return -EAGAIN;
968                 }
969
970                 /* yay, writeable, do it now (without dropping page lock) */
971                 dout(" page %p snapc %p not current, but oldest\n",
972                      page, snapc);
973                 if (!clear_page_dirty_for_io(page))
974                         goto retry_locked;
975                 r = writepage_nounlock(page, NULL);
976                 if (r < 0)
977                         goto fail_nosnap;
978                 goto retry_locked;
979         }
980
981         if (PageUptodate(page)) {
982                 dout(" page %p already uptodate\n", page);
983                 return 0;
984         }
985
986         /* full page? */
987         if (pos_in_page == 0 && len == PAGE_CACHE_SIZE)
988                 return 0;
989
990         /* past end of file? */
991         i_size = inode->i_size;   /* caller holds i_mutex */
992
993         if (i_size + len > inode->i_sb->s_maxbytes) {
994                 /* file is too big */
995                 r = -EINVAL;
996                 goto fail;
997         }
998
999         if (page_off >= i_size ||
1000             (pos_in_page == 0 && (pos+len) >= i_size &&
1001              end_in_page - pos_in_page != PAGE_CACHE_SIZE)) {
1002                 dout(" zeroing %p 0 - %d and %d - %d\n",
1003                      page, pos_in_page, end_in_page, (int)PAGE_CACHE_SIZE);
1004                 zero_user_segments(page,
1005                                    0, pos_in_page,
1006                                    end_in_page, PAGE_CACHE_SIZE);
1007                 return 0;
1008         }
1009
1010         /* we need to read it. */
1011         up_read(&mdsc->snap_rwsem);
1012         r = readpage_nounlock(file, page);
1013         if (r < 0)
1014                 goto fail_nosnap;
1015         goto retry_locked;
1016
1017 fail:
1018         up_read(&mdsc->snap_rwsem);
1019 fail_nosnap:
1020         unlock_page(page);
1021         return r;
1022 }
1023
1024 /*
1025  * We are only allowed to write into/dirty the page if the page is
1026  * clean, or already dirty within the same snap context.
1027  */
1028 static int ceph_write_begin(struct file *file, struct address_space *mapping,
1029                             loff_t pos, unsigned len, unsigned flags,
1030                             struct page **pagep, void **fsdata)
1031 {
1032         struct inode *inode = file->f_dentry->d_inode;
1033         struct page *page;
1034         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1035         int r;
1036
1037         do {
1038                 /* get a page*/
1039                 page = grab_cache_page_write_begin(mapping, index, 0);
1040                 if (!page)
1041                         return -ENOMEM;
1042                 *pagep = page;
1043
1044                 dout("write_begin file %p inode %p page %p %d~%d\n", file,
1045                 inode, page, (int)pos, (int)len);
1046
1047                 r = ceph_update_writeable_page(file, pos, len, page);
1048         } while (r == -EAGAIN);
1049
1050         return r;
1051 }
1052
1053 /*
1054  * we don't do anything in here that simple_write_end doesn't do
1055  * except adjust dirty page accounting and drop read lock on
1056  * mdsc->snap_rwsem.
1057  */
1058 static int ceph_write_end(struct file *file, struct address_space *mapping,
1059                           loff_t pos, unsigned len, unsigned copied,
1060                           struct page *page, void *fsdata)
1061 {
1062         struct inode *inode = file->f_dentry->d_inode;
1063         struct ceph_client *client = ceph_inode_to_client(inode);
1064         struct ceph_mds_client *mdsc = &client->mdsc;
1065         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1066         int check_cap = 0;
1067
1068         dout("write_end file %p inode %p page %p %d~%d (%d)\n", file,
1069              inode, page, (int)pos, (int)copied, (int)len);
1070
1071         /* zero the stale part of the page if we did a short copy */
1072         if (copied < len)
1073                 zero_user_segment(page, from+copied, len);
1074
1075         /* did file size increase? */
1076         /* (no need for i_size_read(); we caller holds i_mutex */
1077         if (pos+copied > inode->i_size)
1078                 check_cap = ceph_inode_set_size(inode, pos+copied);
1079
1080         if (!PageUptodate(page))
1081                 SetPageUptodate(page);
1082
1083         set_page_dirty(page);
1084
1085         unlock_page(page);
1086         up_read(&mdsc->snap_rwsem);
1087         page_cache_release(page);
1088
1089         if (check_cap)
1090                 ceph_check_caps(ceph_inode(inode), CHECK_CAPS_AUTHONLY, NULL);
1091
1092         return copied;
1093 }
1094
1095 /*
1096  * we set .direct_IO to indicate direct io is supported, but since we
1097  * intercept O_DIRECT reads and writes early, this function should
1098  * never get called.
1099  */
1100 static ssize_t ceph_direct_io(int rw, struct kiocb *iocb,
1101                               const struct iovec *iov,
1102                               loff_t pos, unsigned long nr_segs)
1103 {
1104         WARN_ON(1);
1105         return -EINVAL;
1106 }
1107
1108 const struct address_space_operations ceph_aops = {
1109         .readpage = ceph_readpage,
1110         .readpages = ceph_readpages,
1111         .writepage = ceph_writepage,
1112         .writepages = ceph_writepages_start,
1113         .write_begin = ceph_write_begin,
1114         .write_end = ceph_write_end,
1115         .set_page_dirty = ceph_set_page_dirty,
1116         .invalidatepage = ceph_invalidatepage,
1117         .releasepage = ceph_releasepage,
1118         .direct_IO = ceph_direct_io,
1119 };
1120
1121
1122 /*
1123  * vm ops
1124  */
1125
1126 /*
1127  * Reuse write_begin here for simplicity.
1128  */
1129 static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
1130 {
1131         struct inode *inode = vma->vm_file->f_dentry->d_inode;
1132         struct page *page = vmf->page;
1133         struct ceph_mds_client *mdsc = &ceph_inode_to_client(inode)->mdsc;
1134         loff_t off = page->index << PAGE_CACHE_SHIFT;
1135         loff_t size, len;
1136         int ret;
1137
1138         size = i_size_read(inode);
1139         if (off + PAGE_CACHE_SIZE <= size)
1140                 len = PAGE_CACHE_SIZE;
1141         else
1142                 len = size & ~PAGE_CACHE_MASK;
1143
1144         dout("page_mkwrite %p %llu~%llu page %p idx %lu\n", inode,
1145              off, len, page, page->index);
1146
1147         lock_page(page);
1148
1149         ret = VM_FAULT_NOPAGE;
1150         if ((off > size) ||
1151             (page->mapping != inode->i_mapping))
1152                 goto out;
1153
1154         ret = ceph_update_writeable_page(vma->vm_file, off, len, page);
1155         if (ret == 0) {
1156                 /* success.  we'll keep the page locked. */
1157                 set_page_dirty(page);
1158                 up_read(&mdsc->snap_rwsem);
1159                 ret = VM_FAULT_LOCKED;
1160         } else {
1161                 if (ret == -ENOMEM)
1162                         ret = VM_FAULT_OOM;
1163                 else
1164                         ret = VM_FAULT_SIGBUS;
1165         }
1166 out:
1167         dout("page_mkwrite %p %llu~%llu = %d\n", inode, off, len, ret);
1168         if (ret != VM_FAULT_LOCKED)
1169                 unlock_page(page);
1170         return ret;
1171 }
1172
1173 static struct vm_operations_struct ceph_vmops = {
1174         .fault          = filemap_fault,
1175         .page_mkwrite   = ceph_page_mkwrite,
1176 };
1177
1178 int ceph_mmap(struct file *file, struct vm_area_struct *vma)
1179 {
1180         struct address_space *mapping = file->f_mapping;
1181
1182         if (!mapping->a_ops->readpage)
1183                 return -ENOEXEC;
1184         file_accessed(file);
1185         vma->vm_ops = &ceph_vmops;
1186         vma->vm_flags |= VM_CAN_NONLINEAR;
1187         return 0;
1188 }