ceph: whitespace cleanup
[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/slab.h>
9 #include <linux/pagevec.h>
10 #include <linux/task_io_accounting_ops.h>
11
12 #include "super.h"
13 #include "osd_client.h"
14
15 /*
16  * Ceph address space ops.
17  *
18  * There are a few funny things going on here.
19  *
20  * The page->private field is used to reference a struct
21  * ceph_snap_context for _every_ dirty page.  This indicates which
22  * snapshot the page was logically dirtied in, and thus which snap
23  * context needs to be associated with the osd write during writeback.
24  *
25  * Similarly, struct ceph_inode_info maintains a set of counters to
26  * count dirty pages on the inode.  In the absense of snapshots,
27  * i_wrbuffer_ref == i_wrbuffer_ref_head == the dirty page count.
28  *
29  * When a snapshot is taken (that is, when the client receives
30  * notification that a snapshot was taken), each inode with caps and
31  * with dirty pages (dirty pages implies there is a cap) gets a new
32  * ceph_cap_snap in the i_cap_snaps list (which is sorted in ascending
33  * order, new snaps go to the tail).  The i_wrbuffer_ref_head count is
34  * moved to capsnap->dirty. (Unless a sync write is currently in
35  * progress.  In that case, the capsnap is said to be "pending", new
36  * writes cannot start, and the capsnap isn't "finalized" until the
37  * write completes (or fails) and a final size/mtime for the inode for
38  * that snap can be settled upon.)  i_wrbuffer_ref_head is reset to 0.
39  *
40  * On writeback, we must submit writes to the osd IN SNAP ORDER.  So,
41  * we look for the first capsnap in i_cap_snaps and write out pages in
42  * that snap context _only_.  Then we move on to the next capsnap,
43  * eventually reaching the "live" or "head" context (i.e., pages that
44  * are not yet snapped) and are writing the most recently dirtied
45  * pages.
46  *
47  * Invalidate and so forth must take care to ensure the dirty page
48  * accounting is preserved.
49  */
50
51 #define CONGESTION_ON_THRESH(congestion_kb) (congestion_kb >> (PAGE_SHIFT-10))
52 #define CONGESTION_OFF_THRESH(congestion_kb)                            \
53         (CONGESTION_ON_THRESH(congestion_kb) -                          \
54          (CONGESTION_ON_THRESH(congestion_kb) >> 2))
55
56
57
58 /*
59  * Dirty a page.  Optimistically adjust accounting, on the assumption
60  * that we won't race with invalidate.  If we do, readjust.
61  */
62 static int ceph_set_page_dirty(struct page *page)
63 {
64         struct address_space *mapping = page->mapping;
65         struct inode *inode;
66         struct ceph_inode_info *ci;
67         int undo = 0;
68         struct ceph_snap_context *snapc;
69
70         if (unlikely(!mapping))
71                 return !TestSetPageDirty(page);
72
73         if (TestSetPageDirty(page)) {
74                 dout("%p set_page_dirty %p idx %lu -- already dirty\n",
75                      mapping->host, page, page->index);
76                 return 0;
77         }
78
79         inode = mapping->host;
80         ci = ceph_inode(inode);
81
82         /*
83          * Note that we're grabbing a snapc ref here without holding
84          * any locks!
85          */
86         snapc = ceph_get_snap_context(ci->i_snap_realm->cached_context);
87
88         /* dirty the head */
89         spin_lock(&inode->i_lock);
90         if (ci->i_wrbuffer_ref_head == 0)
91                 ci->i_head_snapc = ceph_get_snap_context(snapc);
92         ++ci->i_wrbuffer_ref_head;
93         if (ci->i_wrbuffer_ref == 0)
94                 igrab(inode);
95         ++ci->i_wrbuffer_ref;
96         dout("%p set_page_dirty %p idx %lu head %d/%d -> %d/%d "
97              "snapc %p seq %lld (%d snaps)\n",
98              mapping->host, page, page->index,
99              ci->i_wrbuffer_ref-1, ci->i_wrbuffer_ref_head-1,
100              ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
101              snapc, snapc->seq, snapc->num_snaps);
102         spin_unlock(&inode->i_lock);
103
104         /* now adjust page */
105         spin_lock_irq(&mapping->tree_lock);
106         if (page->mapping) {    /* Race with truncate? */
107                 WARN_ON_ONCE(!PageUptodate(page));
108
109                 if (mapping_cap_account_dirty(mapping)) {
110                         __inc_zone_page_state(page, NR_FILE_DIRTY);
111                         __inc_bdi_stat(mapping->backing_dev_info,
112                                         BDI_RECLAIMABLE);
113                         task_io_account_write(PAGE_CACHE_SIZE);
114                 }
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  */
146 static 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 = (void *)page->private;
151
152         BUG_ON(!PageLocked(page));
153         BUG_ON(!page->private);
154         BUG_ON(!PagePrivate(page));
155         BUG_ON(!page->mapping);
156
157         inode = page->mapping->host;
158
159         /*
160          * We can get non-dirty pages here due to races between
161          * set_page_dirty and truncate_complete_page; just spit out a
162          * warning, in case we end up with accounting problems later.
163          */
164         if (!PageDirty(page))
165                 pr_err("%p invalidatepage %p page not dirty\n", inode, page);
166
167         if (offset == 0)
168                 ClearPageChecked(page);
169
170         ci = ceph_inode(inode);
171         if (offset == 0) {
172                 dout("%p invalidatepage %p idx %lu full dirty page %lu\n",
173                      inode, page, page->index, offset);
174                 ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
175                 ceph_put_snap_context(snapc);
176                 page->private = 0;
177                 ClearPagePrivate(page);
178         } else {
179                 dout("%p invalidatepage %p idx %lu partial dirty page\n",
180                      inode, page, page->index);
181         }
182 }
183
184 /* just a sanity check */
185 static int ceph_releasepage(struct page *page, gfp_t g)
186 {
187         struct inode *inode = page->mapping ? page->mapping->host : NULL;
188         dout("%p releasepage %p idx %lu\n", inode, page, page->index);
189         WARN_ON(PageDirty(page));
190         WARN_ON(page->private);
191         WARN_ON(PagePrivate(page));
192         return 0;
193 }
194
195 /*
196  * read a single page, without unlocking it.
197  */
198 static int readpage_nounlock(struct file *filp, struct page *page)
199 {
200         struct inode *inode = filp->f_dentry->d_inode;
201         struct ceph_inode_info *ci = ceph_inode(inode);
202         struct ceph_osd_client *osdc = &ceph_inode_to_client(inode)->osdc;
203         int err = 0;
204         u64 len = PAGE_CACHE_SIZE;
205
206         dout("readpage inode %p file %p page %p index %lu\n",
207              inode, filp, page, page->index);
208         err = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
209                                   page->index << PAGE_CACHE_SHIFT, &len,
210                                   ci->i_truncate_seq, ci->i_truncate_size,
211                                   &page, 1);
212         if (err == -ENOENT)
213                 err = 0;
214         if (err < 0) {
215                 SetPageError(page);
216                 goto out;
217         } else if (err < PAGE_CACHE_SIZE) {
218                 /* zero fill remainder of page */
219                 zero_user_segment(page, err, PAGE_CACHE_SIZE);
220         }
221         SetPageUptodate(page);
222
223 out:
224         return err < 0 ? err : 0;
225 }
226
227 static int ceph_readpage(struct file *filp, struct page *page)
228 {
229         int r = readpage_nounlock(filp, page);
230         unlock_page(page);
231         return r;
232 }
233
234 /*
235  * Build a vector of contiguous pages from the provided page list.
236  */
237 static struct page **page_vector_from_list(struct list_head *page_list,
238                                            unsigned *nr_pages)
239 {
240         struct page **pages;
241         struct page *page;
242         int next_index, contig_pages = 0;
243
244         /* build page vector */
245         pages = kmalloc(sizeof(*pages) * *nr_pages, GFP_NOFS);
246         if (!pages)
247                 return ERR_PTR(-ENOMEM);
248
249         BUG_ON(list_empty(page_list));
250         next_index = list_entry(page_list->prev, struct page, lru)->index;
251         list_for_each_entry_reverse(page, page_list, lru) {
252                 if (page->index == next_index) {
253                         dout("readpages page %d %p\n", contig_pages, page);
254                         pages[contig_pages] = page;
255                         contig_pages++;
256                         next_index++;
257                 } else {
258                         break;
259                 }
260         }
261         *nr_pages = contig_pages;
262         return pages;
263 }
264
265 /*
266  * Read multiple pages.  Leave pages we don't read + unlock in page_list;
267  * the caller (VM) cleans them up.
268  */
269 static int ceph_readpages(struct file *file, struct address_space *mapping,
270                           struct list_head *page_list, unsigned nr_pages)
271 {
272         struct inode *inode = file->f_dentry->d_inode;
273         struct ceph_inode_info *ci = ceph_inode(inode);
274         struct ceph_osd_client *osdc = &ceph_inode_to_client(inode)->osdc;
275         int rc = 0;
276         struct page **pages;
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         for (; !list_empty(page_list) && len > 0;
300              rc -= PAGE_CACHE_SIZE, len -= PAGE_CACHE_SIZE) {
301                 struct page *page =
302                         list_entry(page_list->prev, struct page, lru);
303
304                 list_del(&page->lru);
305
306                 if (rc < (int)PAGE_CACHE_SIZE) {
307                         /* zero (remainder of) page */
308                         int s = rc < 0 ? 0 : rc;
309                         zero_user_segment(page, s, PAGE_CACHE_SIZE);
310                 }
311
312                 if (add_to_page_cache_lru(page, mapping, page->index,
313                                           GFP_NOFS)) {
314                         page_cache_release(page);
315                         dout("readpages %p add_to_page_cache failed %p\n",
316                              inode, page);
317                         continue;
318                 }
319                 dout("readpages %p adding %p idx %lu\n", inode, page,
320                      page->index);
321                 flush_dcache_page(page);
322                 SetPageUptodate(page);
323                 unlock_page(page);
324                 page_cache_release(page);
325         }
326         rc = 0;
327
328 out:
329         kfree(pages);
330         return rc;
331 }
332
333 /*
334  * Get ref for the oldest snapc for an inode with dirty data... that is, the
335  * only snap context we are allowed to write back.
336  */
337 static struct ceph_snap_context *get_oldest_context(struct inode *inode,
338                                                     u64 *snap_size)
339 {
340         struct ceph_inode_info *ci = ceph_inode(inode);
341         struct ceph_snap_context *snapc = NULL;
342         struct ceph_cap_snap *capsnap = NULL;
343
344         spin_lock(&inode->i_lock);
345         list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
346                 dout(" cap_snap %p snapc %p has %d dirty pages\n", capsnap,
347                      capsnap->context, capsnap->dirty_pages);
348                 if (capsnap->dirty_pages) {
349                         snapc = ceph_get_snap_context(capsnap->context);
350                         if (snap_size)
351                                 *snap_size = capsnap->size;
352                         break;
353                 }
354         }
355         if (!snapc && ci->i_head_snapc) {
356                 snapc = ceph_get_snap_context(ci->i_head_snapc);
357                 dout(" head snapc %p has %d dirty pages\n",
358                      snapc, ci->i_wrbuffer_ref_head);
359         }
360         spin_unlock(&inode->i_lock);
361         return snapc;
362 }
363
364 /*
365  * Write a single page, but leave the page locked.
366  *
367  * If we get a write error, set the page error bit, but still adjust the
368  * dirty page accounting (i.e., page is no longer dirty).
369  */
370 static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
371 {
372         struct inode *inode;
373         struct ceph_inode_info *ci;
374         struct ceph_client *client;
375         struct ceph_osd_client *osdc;
376         loff_t page_off = page->index << PAGE_CACHE_SHIFT;
377         int len = PAGE_CACHE_SIZE;
378         loff_t i_size;
379         int err = 0;
380         struct ceph_snap_context *snapc, *oldest;
381         u64 snap_size = 0;
382         long writeback_stat;
383
384         dout("writepage %p idx %lu\n", page, page->index);
385
386         if (!page->mapping || !page->mapping->host) {
387                 dout("writepage %p - no mapping\n", page);
388                 return -EFAULT;
389         }
390         inode = page->mapping->host;
391         ci = ceph_inode(inode);
392         client = ceph_inode_to_client(inode);
393         osdc = &client->osdc;
394
395         /* verify this is a writeable snap context */
396         snapc = (void *)page->private;
397         if (snapc == NULL) {
398                 dout("writepage %p page %p not dirty?\n", inode, page);
399                 goto out;
400         }
401         oldest = get_oldest_context(inode, &snap_size);
402         if (snapc->seq > oldest->seq) {
403                 dout("writepage %p page %p snapc %p not writeable - noop\n",
404                      inode, page, (void *)page->private);
405                 /* we should only noop if called by kswapd */
406                 WARN_ON((current->flags & PF_MEMALLOC) == 0);
407                 ceph_put_snap_context(oldest);
408                 goto out;
409         }
410         ceph_put_snap_context(oldest);
411
412         /* is this a partial page at end of file? */
413         if (snap_size)
414                 i_size = snap_size;
415         else
416                 i_size = i_size_read(inode);
417         if (i_size < page_off + len)
418                 len = i_size - page_off;
419
420         dout("writepage %p page %p index %lu on %llu~%u\n",
421              inode, page, page->index, page_off, len);
422
423         writeback_stat = atomic_long_inc_return(&client->writeback_count);
424         if (writeback_stat >
425             CONGESTION_ON_THRESH(client->mount_args->congestion_kb))
426                 set_bdi_congested(&client->backing_dev_info, BLK_RW_ASYNC);
427
428         set_page_writeback(page);
429         err = ceph_osdc_writepages(osdc, ceph_vino(inode),
430                                    &ci->i_layout, snapc,
431                                    page_off, len,
432                                    ci->i_truncate_seq, ci->i_truncate_size,
433                                    &inode->i_mtime,
434                                    &page, 1, 0, 0, true);
435         if (err < 0) {
436                 dout("writepage setting page/mapping error %d %p\n", err, page);
437                 SetPageError(page);
438                 mapping_set_error(&inode->i_data, err);
439                 if (wbc)
440                         wbc->pages_skipped++;
441         } else {
442                 dout("writepage cleaned page %p\n", page);
443                 err = 0;  /* vfs expects us to return 0 */
444         }
445         page->private = 0;
446         ClearPagePrivate(page);
447         end_page_writeback(page);
448         ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
449         ceph_put_snap_context(snapc);  /* page's reference */
450 out:
451         return err;
452 }
453
454 static int ceph_writepage(struct page *page, struct writeback_control *wbc)
455 {
456         int err;
457         struct inode *inode = page->mapping->host;
458         BUG_ON(!inode);
459         igrab(inode);
460         err = writepage_nounlock(page, wbc);
461         unlock_page(page);
462         iput(inode);
463         return err;
464 }
465
466
467 /*
468  * lame release_pages helper.  release_pages() isn't exported to
469  * modules.
470  */
471 static void ceph_release_pages(struct page **pages, int num)
472 {
473         struct pagevec pvec;
474         int i;
475
476         pagevec_init(&pvec, 0);
477         for (i = 0; i < num; i++) {
478                 if (pagevec_add(&pvec, pages[i]) == 0)
479                         pagevec_release(&pvec);
480         }
481         pagevec_release(&pvec);
482 }
483
484
485 /*
486  * async writeback completion handler.
487  *
488  * If we get an error, set the mapping error bit, but not the individual
489  * page error bits.
490  */
491 static void writepages_finish(struct ceph_osd_request *req,
492                               struct ceph_msg *msg)
493 {
494         struct inode *inode = req->r_inode;
495         struct ceph_osd_reply_head *replyhead;
496         struct ceph_osd_op *op;
497         struct ceph_inode_info *ci = ceph_inode(inode);
498         unsigned wrote;
499         struct page *page;
500         int i;
501         struct ceph_snap_context *snapc = req->r_snapc;
502         struct address_space *mapping = inode->i_mapping;
503         __s32 rc = -EIO;
504         u64 bytes = 0;
505         struct ceph_client *client = ceph_inode_to_client(inode);
506         long writeback_stat;
507         unsigned issued = ceph_caps_issued(ci);
508
509         /* parse reply */
510         replyhead = msg->front.iov_base;
511         WARN_ON(le32_to_cpu(replyhead->num_ops) == 0);
512         op = (void *)(replyhead + 1);
513         rc = le32_to_cpu(replyhead->result);
514         bytes = le64_to_cpu(op->extent.length);
515
516         if (rc >= 0) {
517                 /*
518                  * Assume we wrote the pages we originally sent.  The
519                  * osd might reply with fewer pages if our writeback
520                  * raced with a truncation and was adjusted at the osd,
521                  * so don't believe the reply.
522                  */
523                 wrote = req->r_num_pages;
524         } else {
525                 wrote = 0;
526                 mapping_set_error(mapping, rc);
527         }
528         dout("writepages_finish %p rc %d bytes %llu wrote %d (pages)\n",
529              inode, rc, bytes, wrote);
530
531         /* clean all pages */
532         for (i = 0; i < req->r_num_pages; i++) {
533                 page = req->r_pages[i];
534                 BUG_ON(!page);
535                 WARN_ON(!PageUptodate(page));
536
537                 writeback_stat =
538                         atomic_long_dec_return(&client->writeback_count);
539                 if (writeback_stat <
540                     CONGESTION_OFF_THRESH(client->mount_args->congestion_kb))
541                         clear_bdi_congested(&client->backing_dev_info,
542                                             BLK_RW_ASYNC);
543
544                 ceph_put_snap_context((void *)page->private);
545                 page->private = 0;
546                 ClearPagePrivate(page);
547                 dout("unlocking %d %p\n", i, page);
548                 end_page_writeback(page);
549
550                 /*
551                  * We lost the cache cap, need to truncate the page before
552                  * it is unlocked, otherwise we'd truncate it later in the
553                  * page truncation thread, possibly losing some data that
554                  * raced its way in
555                  */
556                 if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0)
557                         generic_error_remove_page(inode->i_mapping, page);
558
559                 unlock_page(page);
560         }
561         dout("%p wrote+cleaned %d pages\n", inode, wrote);
562         ceph_put_wrbuffer_cap_refs(ci, req->r_num_pages, snapc);
563
564         ceph_release_pages(req->r_pages, req->r_num_pages);
565         if (req->r_pages_from_pool)
566                 mempool_free(req->r_pages,
567                              ceph_sb_to_client(inode->i_sb)->wb_pagevec_pool);
568         else
569                 kfree(req->r_pages);
570         ceph_osdc_put_request(req);
571 }
572
573 /*
574  * allocate a page vec, either directly, or if necessary, via a the
575  * mempool.  we avoid the mempool if we can because req->r_num_pages
576  * may be less than the maximum write size.
577  */
578 static void alloc_page_vec(struct ceph_client *client,
579                            struct ceph_osd_request *req)
580 {
581         req->r_pages = kmalloc(sizeof(struct page *) * req->r_num_pages,
582                                GFP_NOFS);
583         if (!req->r_pages) {
584                 req->r_pages = mempool_alloc(client->wb_pagevec_pool, GFP_NOFS);
585                 req->r_pages_from_pool = 1;
586                 WARN_ON(!req->r_pages);
587         }
588 }
589
590 /*
591  * initiate async writeback
592  */
593 static int ceph_writepages_start(struct address_space *mapping,
594                                  struct writeback_control *wbc)
595 {
596         struct inode *inode = mapping->host;
597         struct backing_dev_info *bdi = mapping->backing_dev_info;
598         struct ceph_inode_info *ci = ceph_inode(inode);
599         struct ceph_client *client;
600         pgoff_t index, start, end;
601         int range_whole = 0;
602         int should_loop = 1;
603         pgoff_t max_pages = 0, max_pages_ever = 0;
604         struct ceph_snap_context *snapc = NULL, *last_snapc = NULL, *pgsnapc;
605         struct pagevec pvec;
606         int done = 0;
607         int rc = 0;
608         unsigned wsize = 1 << inode->i_blkbits;
609         struct ceph_osd_request *req = NULL;
610         int do_sync;
611         u64 snap_size = 0;
612
613         /*
614          * Include a 'sync' in the OSD request if this is a data
615          * integrity write (e.g., O_SYNC write or fsync()), or if our
616          * cap is being revoked.
617          */
618         do_sync = wbc->sync_mode == WB_SYNC_ALL;
619         if (ceph_caps_revoking(ci, CEPH_CAP_FILE_BUFFER))
620                 do_sync = 1;
621         dout("writepages_start %p dosync=%d (mode=%s)\n",
622              inode, do_sync,
623              wbc->sync_mode == WB_SYNC_NONE ? "NONE" :
624              (wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD"));
625
626         client = ceph_inode_to_client(inode);
627         if (client->mount_state == CEPH_MOUNT_SHUTDOWN) {
628                 pr_warning("writepage_start %p on forced umount\n", inode);
629                 return -EIO; /* we're in a forced umount, don't write! */
630         }
631         if (client->mount_args->wsize && client->mount_args->wsize < wsize)
632                 wsize = client->mount_args->wsize;
633         if (wsize < PAGE_CACHE_SIZE)
634                 wsize = PAGE_CACHE_SIZE;
635         max_pages_ever = wsize >> PAGE_CACHE_SHIFT;
636
637         pagevec_init(&pvec, 0);
638
639         /* ?? */
640         if (wbc->nonblocking && bdi_write_congested(bdi)) {
641                 dout(" writepages congested\n");
642                 wbc->encountered_congestion = 1;
643                 goto out_final;
644         }
645
646         /* where to start/end? */
647         if (wbc->range_cyclic) {
648                 start = mapping->writeback_index; /* Start from prev offset */
649                 end = -1;
650                 dout(" cyclic, start at %lu\n", start);
651         } else {
652                 start = wbc->range_start >> PAGE_CACHE_SHIFT;
653                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
654                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
655                         range_whole = 1;
656                 should_loop = 0;
657                 dout(" not cyclic, %lu to %lu\n", start, end);
658         }
659         index = start;
660
661 retry:
662         /* find oldest snap context with dirty data */
663         ceph_put_snap_context(snapc);
664         snapc = get_oldest_context(inode, &snap_size);
665         if (!snapc) {
666                 /* hmm, why does writepages get called when there
667                    is no dirty data? */
668                 dout(" no snap context with dirty data?\n");
669                 goto out;
670         }
671         dout(" oldest snapc is %p seq %lld (%d snaps)\n",
672              snapc, snapc->seq, snapc->num_snaps);
673         if (last_snapc && snapc != last_snapc) {
674                 /* if we switched to a newer snapc, restart our scan at the
675                  * start of the original file range. */
676                 dout("  snapc differs from last pass, restarting at %lu\n",
677                      index);
678                 index = start;
679         }
680         last_snapc = snapc;
681
682         while (!done && index <= end) {
683                 unsigned i;
684                 int first;
685                 pgoff_t next;
686                 int pvec_pages, locked_pages;
687                 struct page *page;
688                 int want;
689                 u64 offset, len;
690                 struct ceph_osd_request_head *reqhead;
691                 struct ceph_osd_op *op;
692                 long writeback_stat;
693
694                 next = 0;
695                 locked_pages = 0;
696                 max_pages = max_pages_ever;
697
698 get_more_pages:
699                 first = -1;
700                 want = min(end - index,
701                            min((pgoff_t)PAGEVEC_SIZE,
702                                max_pages - (pgoff_t)locked_pages) - 1)
703                         + 1;
704                 pvec_pages = pagevec_lookup_tag(&pvec, mapping, &index,
705                                                 PAGECACHE_TAG_DIRTY,
706                                                 want);
707                 dout("pagevec_lookup_tag got %d\n", pvec_pages);
708                 if (!pvec_pages && !locked_pages)
709                         break;
710                 for (i = 0; i < pvec_pages && locked_pages < max_pages; i++) {
711                         page = pvec.pages[i];
712                         dout("? %p idx %lu\n", page, page->index);
713                         if (locked_pages == 0)
714                                 lock_page(page);  /* first page */
715                         else if (!trylock_page(page))
716                                 break;
717
718                         /* only dirty pages, or our accounting breaks */
719                         if (unlikely(!PageDirty(page)) ||
720                             unlikely(page->mapping != mapping)) {
721                                 dout("!dirty or !mapping %p\n", page);
722                                 unlock_page(page);
723                                 break;
724                         }
725                         if (!wbc->range_cyclic && page->index > end) {
726                                 dout("end of range %p\n", page);
727                                 done = 1;
728                                 unlock_page(page);
729                                 break;
730                         }
731                         if (next && (page->index != next)) {
732                                 dout("not consecutive %p\n", page);
733                                 unlock_page(page);
734                                 break;
735                         }
736                         if (wbc->sync_mode != WB_SYNC_NONE) {
737                                 dout("waiting on writeback %p\n", page);
738                                 wait_on_page_writeback(page);
739                         }
740                         if ((snap_size && page_offset(page) > snap_size) ||
741                             (!snap_size &&
742                              page_offset(page) > i_size_read(inode))) {
743                                 dout("%p page eof %llu\n", page, snap_size ?
744                                      snap_size : i_size_read(inode));
745                                 done = 1;
746                                 unlock_page(page);
747                                 break;
748                         }
749                         if (PageWriteback(page)) {
750                                 dout("%p under writeback\n", page);
751                                 unlock_page(page);
752                                 break;
753                         }
754
755                         /* only if matching snap context */
756                         pgsnapc = (void *)page->private;
757                         if (pgsnapc->seq > snapc->seq) {
758                                 dout("page snapc %p %lld > oldest %p %lld\n",
759                                      pgsnapc, pgsnapc->seq, snapc, snapc->seq);
760                                 unlock_page(page);
761                                 if (!locked_pages)
762                                         continue; /* keep looking for snap */
763                                 break;
764                         }
765
766                         if (!clear_page_dirty_for_io(page)) {
767                                 dout("%p !clear_page_dirty_for_io\n", page);
768                                 unlock_page(page);
769                                 break;
770                         }
771
772                         /* ok */
773                         if (locked_pages == 0) {
774                                 /* prepare async write request */
775                                 offset = page->index << PAGE_CACHE_SHIFT;
776                                 len = wsize;
777                                 req = ceph_osdc_new_request(&client->osdc,
778                                             &ci->i_layout,
779                                             ceph_vino(inode),
780                                             offset, &len,
781                                             CEPH_OSD_OP_WRITE,
782                                             CEPH_OSD_FLAG_WRITE |
783                                                     CEPH_OSD_FLAG_ONDISK,
784                                             snapc, do_sync,
785                                             ci->i_truncate_seq,
786                                             ci->i_truncate_size,
787                                             &inode->i_mtime, true, 1);
788                                 max_pages = req->r_num_pages;
789
790                                 alloc_page_vec(client, req);
791                                 req->r_callback = writepages_finish;
792                                 req->r_inode = inode;
793                         }
794
795                         /* note position of first page in pvec */
796                         if (first < 0)
797                                 first = i;
798                         dout("%p will write page %p idx %lu\n",
799                              inode, page, page->index);
800
801                         writeback_stat =
802                                atomic_long_inc_return(&client->writeback_count);
803                         if (writeback_stat > CONGESTION_ON_THRESH(
804                                     client->mount_args->congestion_kb)) {
805                                 set_bdi_congested(&client->backing_dev_info,
806                                                   BLK_RW_ASYNC);
807                         }
808
809                         set_page_writeback(page);
810                         req->r_pages[locked_pages] = page;
811                         locked_pages++;
812                         next = page->index + 1;
813                 }
814
815                 /* did we get anything? */
816                 if (!locked_pages)
817                         goto release_pvec_pages;
818                 if (i) {
819                         int j;
820                         BUG_ON(!locked_pages || first < 0);
821
822                         if (pvec_pages && i == pvec_pages &&
823                             locked_pages < max_pages) {
824                                 dout("reached end pvec, trying for more\n");
825                                 pagevec_reinit(&pvec);
826                                 goto get_more_pages;
827                         }
828
829                         /* shift unused pages over in the pvec...  we
830                          * will need to release them below. */
831                         for (j = i; j < pvec_pages; j++) {
832                                 dout(" pvec leftover page %p\n",
833                                      pvec.pages[j]);
834                                 pvec.pages[j-i+first] = pvec.pages[j];
835                         }
836                         pvec.nr -= i-first;
837                 }
838
839                 /* submit the write */
840                 offset = req->r_pages[0]->index << PAGE_CACHE_SHIFT;
841                 len = min((snap_size ? snap_size : i_size_read(inode)) - offset,
842                           (u64)locked_pages << PAGE_CACHE_SHIFT);
843                 dout("writepages got %d pages at %llu~%llu\n",
844                      locked_pages, offset, len);
845
846                 /* revise final length, page count */
847                 req->r_num_pages = locked_pages;
848                 reqhead = req->r_request->front.iov_base;
849                 op = (void *)(reqhead + 1);
850                 op->extent.length = cpu_to_le64(len);
851                 op->payload_len = cpu_to_le32(len);
852                 req->r_request->hdr.data_len = cpu_to_le32(len);
853
854                 ceph_osdc_start_request(&client->osdc, req, true);
855                 req = NULL;
856
857                 /* continue? */
858                 index = next;
859                 wbc->nr_to_write -= locked_pages;
860                 if (wbc->nr_to_write <= 0)
861                         done = 1;
862
863 release_pvec_pages:
864                 dout("pagevec_release on %d pages (%p)\n", (int)pvec.nr,
865                      pvec.nr ? pvec.pages[0] : NULL);
866                 pagevec_release(&pvec);
867
868                 if (locked_pages && !done)
869                         goto retry;
870         }
871
872         if (should_loop && !done) {
873                 /* more to do; loop back to beginning of file */
874                 dout("writepages looping back to beginning of file\n");
875                 should_loop = 0;
876                 index = 0;
877                 goto retry;
878         }
879
880         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
881                 mapping->writeback_index = index;
882
883 out:
884         if (req)
885                 ceph_osdc_put_request(req);
886         if (rc > 0)
887                 rc = 0;  /* vfs expects us to return 0 */
888         ceph_put_snap_context(snapc);
889         dout("writepages done, rc = %d\n", rc);
890 out_final:
891         return rc;
892 }
893
894
895
896 /*
897  * See if a given @snapc is either writeable, or already written.
898  */
899 static int context_is_writeable_or_written(struct inode *inode,
900                                            struct ceph_snap_context *snapc)
901 {
902         struct ceph_snap_context *oldest = get_oldest_context(inode, NULL);
903         int ret = !oldest || snapc->seq <= oldest->seq;
904
905         ceph_put_snap_context(oldest);
906         return ret;
907 }
908
909 /*
910  * We are only allowed to write into/dirty the page if the page is
911  * clean, or already dirty within the same snap context.
912  *
913  * called with page locked.
914  * return success with page locked,
915  * or any failure (incl -EAGAIN) with page unlocked.
916  */
917 static int ceph_update_writeable_page(struct file *file,
918                             loff_t pos, unsigned len,
919                             struct page *page)
920 {
921         struct inode *inode = file->f_dentry->d_inode;
922         struct ceph_inode_info *ci = ceph_inode(inode);
923         struct ceph_mds_client *mdsc = &ceph_inode_to_client(inode)->mdsc;
924         loff_t page_off = pos & PAGE_CACHE_MASK;
925         int pos_in_page = pos & ~PAGE_CACHE_MASK;
926         int end_in_page = pos_in_page + len;
927         loff_t i_size;
928         int r;
929         struct ceph_snap_context *snapc, *oldest;
930
931 retry_locked:
932         /* writepages currently holds page lock, but if we change that later, */
933         wait_on_page_writeback(page);
934
935         /* check snap context */
936         BUG_ON(!ci->i_snap_realm);
937         down_read(&mdsc->snap_rwsem);
938         BUG_ON(!ci->i_snap_realm->cached_context);
939         snapc = (void *)page->private;
940         if (snapc && snapc != ci->i_head_snapc) {
941                 /*
942                  * this page is already dirty in another (older) snap
943                  * context!  is it writeable now?
944                  */
945                 oldest = get_oldest_context(inode, NULL);
946                 up_read(&mdsc->snap_rwsem);
947
948                 if (snapc->seq > oldest->seq) {
949                         ceph_put_snap_context(oldest);
950                         dout(" page %p snapc %p not current or oldest\n",
951                              page, snapc);
952                         /*
953                          * queue for writeback, and wait for snapc to
954                          * be writeable or written
955                          */
956                         snapc = ceph_get_snap_context(snapc);
957                         unlock_page(page);
958                         ceph_queue_writeback(inode);
959                         r = wait_event_interruptible(ci->i_cap_wq,
960                                context_is_writeable_or_written(inode, snapc));
961                         ceph_put_snap_context(snapc);
962                         if (r == -ERESTARTSYS)
963                                 return r;
964                         return -EAGAIN;
965                 }
966                 ceph_put_snap_context(oldest);
967
968                 /* yay, writeable, do it now (without dropping page lock) */
969                 dout(" page %p snapc %p not current, but oldest\n",
970                      page, snapc);
971                 if (!clear_page_dirty_for_io(page))
972                         goto retry_locked;
973                 r = writepage_nounlock(page, NULL);
974                 if (r < 0)
975                         goto fail_nosnap;
976                 goto retry_locked;
977         }
978
979         if (PageUptodate(page)) {
980                 dout(" page %p already uptodate\n", page);
981                 return 0;
982         }
983
984         /* full page? */
985         if (pos_in_page == 0 && len == PAGE_CACHE_SIZE)
986                 return 0;
987
988         /* past end of file? */
989         i_size = inode->i_size;   /* caller holds i_mutex */
990
991         if (i_size + len > inode->i_sb->s_maxbytes) {
992                 /* file is too big */
993                 r = -EINVAL;
994                 goto fail;
995         }
996
997         if (page_off >= i_size ||
998             (pos_in_page == 0 && (pos+len) >= i_size &&
999              end_in_page - pos_in_page != PAGE_CACHE_SIZE)) {
1000                 dout(" zeroing %p 0 - %d and %d - %d\n",
1001                      page, pos_in_page, end_in_page, (int)PAGE_CACHE_SIZE);
1002                 zero_user_segments(page,
1003                                    0, pos_in_page,
1004                                    end_in_page, PAGE_CACHE_SIZE);
1005                 return 0;
1006         }
1007
1008         /* we need to read it. */
1009         up_read(&mdsc->snap_rwsem);
1010         r = readpage_nounlock(file, page);
1011         if (r < 0)
1012                 goto fail_nosnap;
1013         goto retry_locked;
1014
1015 fail:
1016         up_read(&mdsc->snap_rwsem);
1017 fail_nosnap:
1018         unlock_page(page);
1019         return r;
1020 }
1021
1022 /*
1023  * We are only allowed to write into/dirty the page if the page is
1024  * clean, or already dirty within the same snap context.
1025  */
1026 static int ceph_write_begin(struct file *file, struct address_space *mapping,
1027                             loff_t pos, unsigned len, unsigned flags,
1028                             struct page **pagep, void **fsdata)
1029 {
1030         struct inode *inode = file->f_dentry->d_inode;
1031         struct page *page;
1032         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1033         int r;
1034
1035         do {
1036                 /* get a page */
1037                 page = grab_cache_page_write_begin(mapping, index, 0);
1038                 if (!page)
1039                         return -ENOMEM;
1040                 *pagep = page;
1041
1042                 dout("write_begin file %p inode %p page %p %d~%d\n", file,
1043                      inode, page, (int)pos, (int)len);
1044
1045                 r = ceph_update_writeable_page(file, pos, len, page);
1046         } while (r == -EAGAIN);
1047
1048         return r;
1049 }
1050
1051 /*
1052  * we don't do anything in here that simple_write_end doesn't do
1053  * except adjust dirty page accounting and drop read lock on
1054  * mdsc->snap_rwsem.
1055  */
1056 static int ceph_write_end(struct file *file, struct address_space *mapping,
1057                           loff_t pos, unsigned len, unsigned copied,
1058                           struct page *page, void *fsdata)
1059 {
1060         struct inode *inode = file->f_dentry->d_inode;
1061         struct ceph_client *client = ceph_inode_to_client(inode);
1062         struct ceph_mds_client *mdsc = &client->mdsc;
1063         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1064         int check_cap = 0;
1065
1066         dout("write_end file %p inode %p page %p %d~%d (%d)\n", file,
1067              inode, page, (int)pos, (int)copied, (int)len);
1068
1069         /* zero the stale part of the page if we did a short copy */
1070         if (copied < len)
1071                 zero_user_segment(page, from+copied, len);
1072
1073         /* did file size increase? */
1074         /* (no need for i_size_read(); we caller holds i_mutex */
1075         if (pos+copied > inode->i_size)
1076                 check_cap = ceph_inode_set_size(inode, pos+copied);
1077
1078         if (!PageUptodate(page))
1079                 SetPageUptodate(page);
1080
1081         set_page_dirty(page);
1082
1083         unlock_page(page);
1084         up_read(&mdsc->snap_rwsem);
1085         page_cache_release(page);
1086
1087         if (check_cap)
1088                 ceph_check_caps(ceph_inode(inode), CHECK_CAPS_AUTHONLY, NULL);
1089
1090         return copied;
1091 }
1092
1093 /*
1094  * we set .direct_IO to indicate direct io is supported, but since we
1095  * intercept O_DIRECT reads and writes early, this function should
1096  * never get called.
1097  */
1098 static ssize_t ceph_direct_io(int rw, struct kiocb *iocb,
1099                               const struct iovec *iov,
1100                               loff_t pos, unsigned long nr_segs)
1101 {
1102         WARN_ON(1);
1103         return -EINVAL;
1104 }
1105
1106 const struct address_space_operations ceph_aops = {
1107         .readpage = ceph_readpage,
1108         .readpages = ceph_readpages,
1109         .writepage = ceph_writepage,
1110         .writepages = ceph_writepages_start,
1111         .write_begin = ceph_write_begin,
1112         .write_end = ceph_write_end,
1113         .set_page_dirty = ceph_set_page_dirty,
1114         .invalidatepage = ceph_invalidatepage,
1115         .releasepage = ceph_releasepage,
1116         .direct_IO = ceph_direct_io,
1117 };
1118
1119
1120 /*
1121  * vm ops
1122  */
1123
1124 /*
1125  * Reuse write_begin here for simplicity.
1126  */
1127 static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
1128 {
1129         struct inode *inode = vma->vm_file->f_dentry->d_inode;
1130         struct page *page = vmf->page;
1131         struct ceph_mds_client *mdsc = &ceph_inode_to_client(inode)->mdsc;
1132         loff_t off = page->index << PAGE_CACHE_SHIFT;
1133         loff_t size, len;
1134         int ret;
1135
1136         size = i_size_read(inode);
1137         if (off + PAGE_CACHE_SIZE <= size)
1138                 len = PAGE_CACHE_SIZE;
1139         else
1140                 len = size & ~PAGE_CACHE_MASK;
1141
1142         dout("page_mkwrite %p %llu~%llu page %p idx %lu\n", inode,
1143              off, len, page, page->index);
1144
1145         lock_page(page);
1146
1147         ret = VM_FAULT_NOPAGE;
1148         if ((off > size) ||
1149             (page->mapping != inode->i_mapping))
1150                 goto out;
1151
1152         ret = ceph_update_writeable_page(vma->vm_file, off, len, page);
1153         if (ret == 0) {
1154                 /* success.  we'll keep the page locked. */
1155                 set_page_dirty(page);
1156                 up_read(&mdsc->snap_rwsem);
1157                 ret = VM_FAULT_LOCKED;
1158         } else {
1159                 if (ret == -ENOMEM)
1160                         ret = VM_FAULT_OOM;
1161                 else
1162                         ret = VM_FAULT_SIGBUS;
1163         }
1164 out:
1165         dout("page_mkwrite %p %llu~%llu = %d\n", inode, off, len, ret);
1166         if (ret != VM_FAULT_LOCKED)
1167                 unlock_page(page);
1168         return ret;
1169 }
1170
1171 static struct vm_operations_struct ceph_vmops = {
1172         .fault          = filemap_fault,
1173         .page_mkwrite   = ceph_page_mkwrite,
1174 };
1175
1176 int ceph_mmap(struct file *file, struct vm_area_struct *vma)
1177 {
1178         struct address_space *mapping = file->f_mapping;
1179
1180         if (!mapping->a_ops->readpage)
1181                 return -ENOEXEC;
1182         file_accessed(file);
1183         vma->vm_ops = &ceph_vmops;
1184         vma->vm_flags |= VM_CAN_NONLINEAR;
1185         return 0;
1186 }