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