ceph: use i_ceph_lock instead of i_lock
[linux-2.6.git] / fs / ceph / addr.c
1 #include <linux/ceph/ceph_debug.h>
2
3 #include <linux/backing-dev.h>
4 #include <linux/fs.h>
5 #include <linux/mm.h>
6 #include <linux/pagemap.h>
7 #include <linux/writeback.h>    /* generic_writepages */
8 #include <linux/slab.h>
9 #include <linux/pagevec.h>
10 #include <linux/task_io_accounting_ops.h>
11
12 #include "super.h"
13 #include "mds_client.h"
14 #include <linux/ceph/osd_client.h>
15
16 /*
17  * Ceph address space ops.
18  *
19  * There are a few funny things going on here.
20  *
21  * The page->private field is used to reference a struct
22  * ceph_snap_context for _every_ dirty page.  This indicates which
23  * snapshot the page was logically dirtied in, and thus which snap
24  * context needs to be associated with the osd write during writeback.
25  *
26  * Similarly, struct ceph_inode_info maintains a set of counters to
27  * count dirty pages on the inode.  In the absence of snapshots,
28  * i_wrbuffer_ref == i_wrbuffer_ref_head == the dirty page count.
29  *
30  * When a snapshot is taken (that is, when the client receives
31  * notification that a snapshot was taken), each inode with caps and
32  * with dirty pages (dirty pages implies there is a cap) gets a new
33  * ceph_cap_snap in the i_cap_snaps list (which is sorted in ascending
34  * order, new snaps go to the tail).  The i_wrbuffer_ref_head count is
35  * moved to capsnap->dirty. (Unless a sync write is currently in
36  * progress.  In that case, the capsnap is said to be "pending", new
37  * writes cannot start, and the capsnap isn't "finalized" until the
38  * write completes (or fails) and a final size/mtime for the inode for
39  * that snap can be settled upon.)  i_wrbuffer_ref_head is reset to 0.
40  *
41  * On writeback, we must submit writes to the osd IN SNAP ORDER.  So,
42  * we look for the first capsnap in i_cap_snaps and write out pages in
43  * that snap context _only_.  Then we move on to the next capsnap,
44  * eventually reaching the "live" or "head" context (i.e., pages that
45  * are not yet snapped) and are writing the most recently dirtied
46  * pages.
47  *
48  * Invalidate and so forth must take care to ensure the dirty page
49  * accounting is preserved.
50  */
51
52 #define CONGESTION_ON_THRESH(congestion_kb) (congestion_kb >> (PAGE_SHIFT-10))
53 #define CONGESTION_OFF_THRESH(congestion_kb)                            \
54         (CONGESTION_ON_THRESH(congestion_kb) -                          \
55          (CONGESTION_ON_THRESH(congestion_kb) >> 2))
56
57
58
59 /*
60  * Dirty a page.  Optimistically adjust accounting, on the assumption
61  * that we won't race with invalidate.  If we do, readjust.
62  */
63 static int ceph_set_page_dirty(struct page *page)
64 {
65         struct address_space *mapping = page->mapping;
66         struct inode *inode;
67         struct ceph_inode_info *ci;
68         int undo = 0;
69         struct ceph_snap_context *snapc;
70
71         if (unlikely(!mapping))
72                 return !TestSetPageDirty(page);
73
74         if (TestSetPageDirty(page)) {
75                 dout("%p set_page_dirty %p idx %lu -- already dirty\n",
76                      mapping->host, page, page->index);
77                 return 0;
78         }
79
80         inode = mapping->host;
81         ci = ceph_inode(inode);
82
83         /*
84          * Note that we're grabbing a snapc ref here without holding
85          * any locks!
86          */
87         snapc = ceph_get_snap_context(ci->i_snap_realm->cached_context);
88
89         /* dirty the head */
90         spin_lock(&ci->i_ceph_lock);
91         if (ci->i_head_snapc == NULL)
92                 ci->i_head_snapc = ceph_get_snap_context(snapc);
93         ++ci->i_wrbuffer_ref_head;
94         if (ci->i_wrbuffer_ref == 0)
95                 ihold(inode);
96         ++ci->i_wrbuffer_ref;
97         dout("%p set_page_dirty %p idx %lu head %d/%d -> %d/%d "
98              "snapc %p seq %lld (%d snaps)\n",
99              mapping->host, page, page->index,
100              ci->i_wrbuffer_ref-1, ci->i_wrbuffer_ref_head-1,
101              ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
102              snapc, snapc->seq, snapc->num_snaps);
103         spin_unlock(&ci->i_ceph_lock);
104
105         /* now adjust page */
106         spin_lock_irq(&mapping->tree_lock);
107         if (page->mapping) {    /* Race with truncate? */
108                 WARN_ON_ONCE(!PageUptodate(page));
109                 account_page_dirtied(page, page->mapping);
110                 radix_tree_tag_set(&mapping->page_tree,
111                                 page_index(page), PAGECACHE_TAG_DIRTY);
112
113                 /*
114                  * Reference snap context in page->private.  Also set
115                  * PagePrivate so that we get invalidatepage callback.
116                  */
117                 page->private = (unsigned long)snapc;
118                 SetPagePrivate(page);
119         } else {
120                 dout("ANON set_page_dirty %p (raced truncate?)\n", page);
121                 undo = 1;
122         }
123
124         spin_unlock_irq(&mapping->tree_lock);
125
126         if (undo)
127                 /* whoops, we failed to dirty the page */
128                 ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
129
130         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
131
132         BUG_ON(!PageDirty(page));
133         return 1;
134 }
135
136 /*
137  * If we are truncating the full page (i.e. offset == 0), adjust the
138  * dirty page counters appropriately.  Only called if there is private
139  * data on the page.
140  */
141 static void ceph_invalidatepage(struct page *page, unsigned long offset)
142 {
143         struct inode *inode;
144         struct ceph_inode_info *ci;
145         struct ceph_snap_context *snapc = (void *)page->private;
146
147         BUG_ON(!PageLocked(page));
148         BUG_ON(!page->private);
149         BUG_ON(!PagePrivate(page));
150         BUG_ON(!page->mapping);
151
152         inode = page->mapping->host;
153
154         /*
155          * We can get non-dirty pages here due to races between
156          * set_page_dirty and truncate_complete_page; just spit out a
157          * warning, in case we end up with accounting problems later.
158          */
159         if (!PageDirty(page))
160                 pr_err("%p invalidatepage %p page not dirty\n", inode, page);
161
162         if (offset == 0)
163                 ClearPageChecked(page);
164
165         ci = ceph_inode(inode);
166         if (offset == 0) {
167                 dout("%p invalidatepage %p idx %lu full dirty page %lu\n",
168                      inode, page, page->index, offset);
169                 ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
170                 ceph_put_snap_context(snapc);
171                 page->private = 0;
172                 ClearPagePrivate(page);
173         } else {
174                 dout("%p invalidatepage %p idx %lu partial dirty page\n",
175                      inode, page, page->index);
176         }
177 }
178
179 /* just a sanity check */
180 static int ceph_releasepage(struct page *page, gfp_t g)
181 {
182         struct inode *inode = page->mapping ? page->mapping->host : NULL;
183         dout("%p releasepage %p idx %lu\n", inode, page, page->index);
184         WARN_ON(PageDirty(page));
185         WARN_ON(page->private);
186         WARN_ON(PagePrivate(page));
187         return 0;
188 }
189
190 /*
191  * read a single page, without unlocking it.
192  */
193 static int readpage_nounlock(struct file *filp, struct page *page)
194 {
195         struct inode *inode = filp->f_dentry->d_inode;
196         struct ceph_inode_info *ci = ceph_inode(inode);
197         struct ceph_osd_client *osdc = 
198                 &ceph_inode_to_client(inode)->client->osdc;
199         int err = 0;
200         u64 len = PAGE_CACHE_SIZE;
201
202         dout("readpage inode %p file %p page %p index %lu\n",
203              inode, filp, page, page->index);
204         err = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
205                                   page->index << PAGE_CACHE_SHIFT, &len,
206                                   ci->i_truncate_seq, ci->i_truncate_size,
207                                   &page, 1, 0);
208         if (err == -ENOENT)
209                 err = 0;
210         if (err < 0) {
211                 SetPageError(page);
212                 goto out;
213         } else if (err < PAGE_CACHE_SIZE) {
214                 /* zero fill remainder of page */
215                 zero_user_segment(page, err, PAGE_CACHE_SIZE);
216         }
217         SetPageUptodate(page);
218
219 out:
220         return err < 0 ? err : 0;
221 }
222
223 static int ceph_readpage(struct file *filp, struct page *page)
224 {
225         int r = readpage_nounlock(filp, page);
226         unlock_page(page);
227         return r;
228 }
229
230 /*
231  * Finish an async read(ahead) op.
232  */
233 static void finish_read(struct ceph_osd_request *req, struct ceph_msg *msg)
234 {
235         struct inode *inode = req->r_inode;
236         struct ceph_osd_reply_head *replyhead;
237         int rc, bytes;
238         int i;
239
240         /* parse reply */
241         replyhead = msg->front.iov_base;
242         WARN_ON(le32_to_cpu(replyhead->num_ops) == 0);
243         rc = le32_to_cpu(replyhead->result);
244         bytes = le32_to_cpu(msg->hdr.data_len);
245
246         dout("finish_read %p req %p rc %d bytes %d\n", inode, req, rc, bytes);
247
248         /* unlock all pages, zeroing any data we didn't read */
249         for (i = 0; i < req->r_num_pages; i++, bytes -= PAGE_CACHE_SIZE) {
250                 struct page *page = req->r_pages[i];
251
252                 if (bytes < (int)PAGE_CACHE_SIZE) {
253                         /* zero (remainder of) page */
254                         int s = bytes < 0 ? 0 : bytes;
255                         zero_user_segment(page, s, PAGE_CACHE_SIZE);
256                 }
257                 dout("finish_read %p uptodate %p idx %lu\n", inode, page,
258                      page->index);
259                 flush_dcache_page(page);
260                 SetPageUptodate(page);
261                 unlock_page(page);
262                 page_cache_release(page);
263         }
264         kfree(req->r_pages);
265 }
266
267 /*
268  * start an async read(ahead) operation.  return nr_pages we submitted
269  * a read for on success, or negative error code.
270  */
271 static int start_read(struct inode *inode, struct list_head *page_list, int max)
272 {
273         struct ceph_osd_client *osdc =
274                 &ceph_inode_to_client(inode)->client->osdc;
275         struct ceph_inode_info *ci = ceph_inode(inode);
276         struct page *page = list_entry(page_list->prev, struct page, lru);
277         struct ceph_osd_request *req;
278         u64 off;
279         u64 len;
280         int i;
281         struct page **pages;
282         pgoff_t next_index;
283         int nr_pages = 0;
284         int ret;
285
286         off = page->index << PAGE_CACHE_SHIFT;
287
288         /* count pages */
289         next_index = page->index;
290         list_for_each_entry_reverse(page, page_list, lru) {
291                 if (page->index != next_index)
292                         break;
293                 nr_pages++;
294                 next_index++;
295                 if (max && nr_pages == max)
296                         break;
297         }
298         len = nr_pages << PAGE_CACHE_SHIFT;
299         dout("start_read %p nr_pages %d is %lld~%lld\n", inode, nr_pages,
300              off, len);
301
302         req = ceph_osdc_new_request(osdc, &ci->i_layout, ceph_vino(inode),
303                                     off, &len,
304                                     CEPH_OSD_OP_READ, CEPH_OSD_FLAG_READ,
305                                     NULL, 0,
306                                     ci->i_truncate_seq, ci->i_truncate_size,
307                                     NULL, false, 1, 0);
308         if (!req)
309                 return -ENOMEM;
310
311         /* build page vector */
312         nr_pages = len >> PAGE_CACHE_SHIFT;
313         pages = kmalloc(sizeof(*pages) * nr_pages, GFP_NOFS);
314         ret = -ENOMEM;
315         if (!pages)
316                 goto out;
317         for (i = 0; i < nr_pages; ++i) {
318                 page = list_entry(page_list->prev, struct page, lru);
319                 BUG_ON(PageLocked(page));
320                 list_del(&page->lru);
321                 
322                 dout("start_read %p adding %p idx %lu\n", inode, page,
323                      page->index);
324                 if (add_to_page_cache_lru(page, &inode->i_data, page->index,
325                                           GFP_NOFS)) {
326                         page_cache_release(page);
327                         dout("start_read %p add_to_page_cache failed %p\n",
328                              inode, page);
329                         nr_pages = i;
330                         goto out_pages;
331                 }
332                 pages[i] = page;
333         }
334         req->r_pages = pages;
335         req->r_num_pages = nr_pages;
336         req->r_callback = finish_read;
337         req->r_inode = inode;
338
339         dout("start_read %p starting %p %lld~%lld\n", inode, req, off, len);
340         ret = ceph_osdc_start_request(osdc, req, false);
341         if (ret < 0)
342                 goto out_pages;
343         ceph_osdc_put_request(req);
344         return nr_pages;
345
346 out_pages:
347         ceph_release_page_vector(pages, nr_pages);
348 out:
349         ceph_osdc_put_request(req);
350         return ret;
351 }
352
353
354 /*
355  * Read multiple pages.  Leave pages we don't read + unlock in page_list;
356  * the caller (VM) cleans them up.
357  */
358 static int ceph_readpages(struct file *file, struct address_space *mapping,
359                           struct list_head *page_list, unsigned nr_pages)
360 {
361         struct inode *inode = file->f_dentry->d_inode;
362         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
363         int rc = 0;
364         int max = 0;
365
366         if (fsc->mount_options->rsize >= PAGE_CACHE_SIZE)
367                 max = (fsc->mount_options->rsize + PAGE_CACHE_SIZE - 1)
368                         >> PAGE_SHIFT;
369
370         dout("readpages %p file %p nr_pages %d max %d\n", inode, file, nr_pages,
371              max);
372         while (!list_empty(page_list)) {
373                 rc = start_read(inode, page_list, max);
374                 if (rc < 0)
375                         goto out;
376                 BUG_ON(rc == 0);
377         }
378 out:
379         dout("readpages %p file %p ret %d\n", inode, file, rc);
380         return rc;
381 }
382
383 /*
384  * Get ref for the oldest snapc for an inode with dirty data... that is, the
385  * only snap context we are allowed to write back.
386  */
387 static struct ceph_snap_context *get_oldest_context(struct inode *inode,
388                                                     u64 *snap_size)
389 {
390         struct ceph_inode_info *ci = ceph_inode(inode);
391         struct ceph_snap_context *snapc = NULL;
392         struct ceph_cap_snap *capsnap = NULL;
393
394         spin_lock(&ci->i_ceph_lock);
395         list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
396                 dout(" cap_snap %p snapc %p has %d dirty pages\n", capsnap,
397                      capsnap->context, capsnap->dirty_pages);
398                 if (capsnap->dirty_pages) {
399                         snapc = ceph_get_snap_context(capsnap->context);
400                         if (snap_size)
401                                 *snap_size = capsnap->size;
402                         break;
403                 }
404         }
405         if (!snapc && ci->i_wrbuffer_ref_head) {
406                 snapc = ceph_get_snap_context(ci->i_head_snapc);
407                 dout(" head snapc %p has %d dirty pages\n",
408                      snapc, ci->i_wrbuffer_ref_head);
409         }
410         spin_unlock(&ci->i_ceph_lock);
411         return snapc;
412 }
413
414 /*
415  * Write a single page, but leave the page locked.
416  *
417  * If we get a write error, set the page error bit, but still adjust the
418  * dirty page accounting (i.e., page is no longer dirty).
419  */
420 static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
421 {
422         struct inode *inode;
423         struct ceph_inode_info *ci;
424         struct ceph_fs_client *fsc;
425         struct ceph_osd_client *osdc;
426         loff_t page_off = page->index << PAGE_CACHE_SHIFT;
427         int len = PAGE_CACHE_SIZE;
428         loff_t i_size;
429         int err = 0;
430         struct ceph_snap_context *snapc, *oldest;
431         u64 snap_size = 0;
432         long writeback_stat;
433
434         dout("writepage %p idx %lu\n", page, page->index);
435
436         if (!page->mapping || !page->mapping->host) {
437                 dout("writepage %p - no mapping\n", page);
438                 return -EFAULT;
439         }
440         inode = page->mapping->host;
441         ci = ceph_inode(inode);
442         fsc = ceph_inode_to_client(inode);
443         osdc = &fsc->client->osdc;
444
445         /* verify this is a writeable snap context */
446         snapc = (void *)page->private;
447         if (snapc == NULL) {
448                 dout("writepage %p page %p not dirty?\n", inode, page);
449                 goto out;
450         }
451         oldest = get_oldest_context(inode, &snap_size);
452         if (snapc->seq > oldest->seq) {
453                 dout("writepage %p page %p snapc %p not writeable - noop\n",
454                      inode, page, (void *)page->private);
455                 /* we should only noop if called by kswapd */
456                 WARN_ON((current->flags & PF_MEMALLOC) == 0);
457                 ceph_put_snap_context(oldest);
458                 goto out;
459         }
460         ceph_put_snap_context(oldest);
461
462         /* is this a partial page at end of file? */
463         if (snap_size)
464                 i_size = snap_size;
465         else
466                 i_size = i_size_read(inode);
467         if (i_size < page_off + len)
468                 len = i_size - page_off;
469
470         dout("writepage %p page %p index %lu on %llu~%u snapc %p\n",
471              inode, page, page->index, page_off, len, snapc);
472
473         writeback_stat = atomic_long_inc_return(&fsc->writeback_count);
474         if (writeback_stat >
475             CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb))
476                 set_bdi_congested(&fsc->backing_dev_info, BLK_RW_ASYNC);
477
478         set_page_writeback(page);
479         err = ceph_osdc_writepages(osdc, ceph_vino(inode),
480                                    &ci->i_layout, snapc,
481                                    page_off, len,
482                                    ci->i_truncate_seq, ci->i_truncate_size,
483                                    &inode->i_mtime,
484                                    &page, 1, 0, 0, true);
485         if (err < 0) {
486                 dout("writepage setting page/mapping error %d %p\n", err, page);
487                 SetPageError(page);
488                 mapping_set_error(&inode->i_data, err);
489                 if (wbc)
490                         wbc->pages_skipped++;
491         } else {
492                 dout("writepage cleaned page %p\n", page);
493                 err = 0;  /* vfs expects us to return 0 */
494         }
495         page->private = 0;
496         ClearPagePrivate(page);
497         end_page_writeback(page);
498         ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
499         ceph_put_snap_context(snapc);  /* page's reference */
500 out:
501         return err;
502 }
503
504 static int ceph_writepage(struct page *page, struct writeback_control *wbc)
505 {
506         int err;
507         struct inode *inode = page->mapping->host;
508         BUG_ON(!inode);
509         ihold(inode);
510         err = writepage_nounlock(page, wbc);
511         unlock_page(page);
512         iput(inode);
513         return err;
514 }
515
516
517 /*
518  * lame release_pages helper.  release_pages() isn't exported to
519  * modules.
520  */
521 static void ceph_release_pages(struct page **pages, int num)
522 {
523         struct pagevec pvec;
524         int i;
525
526         pagevec_init(&pvec, 0);
527         for (i = 0; i < num; i++) {
528                 if (pagevec_add(&pvec, pages[i]) == 0)
529                         pagevec_release(&pvec);
530         }
531         pagevec_release(&pvec);
532 }
533
534
535 /*
536  * async writeback completion handler.
537  *
538  * If we get an error, set the mapping error bit, but not the individual
539  * page error bits.
540  */
541 static void writepages_finish(struct ceph_osd_request *req,
542                               struct ceph_msg *msg)
543 {
544         struct inode *inode = req->r_inode;
545         struct ceph_osd_reply_head *replyhead;
546         struct ceph_osd_op *op;
547         struct ceph_inode_info *ci = ceph_inode(inode);
548         unsigned wrote;
549         struct page *page;
550         int i;
551         struct ceph_snap_context *snapc = req->r_snapc;
552         struct address_space *mapping = inode->i_mapping;
553         __s32 rc = -EIO;
554         u64 bytes = 0;
555         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
556         long writeback_stat;
557         unsigned issued = ceph_caps_issued(ci);
558
559         /* parse reply */
560         replyhead = msg->front.iov_base;
561         WARN_ON(le32_to_cpu(replyhead->num_ops) == 0);
562         op = (void *)(replyhead + 1);
563         rc = le32_to_cpu(replyhead->result);
564         bytes = le64_to_cpu(op->extent.length);
565
566         if (rc >= 0) {
567                 /*
568                  * Assume we wrote the pages we originally sent.  The
569                  * osd might reply with fewer pages if our writeback
570                  * raced with a truncation and was adjusted at the osd,
571                  * so don't believe the reply.
572                  */
573                 wrote = req->r_num_pages;
574         } else {
575                 wrote = 0;
576                 mapping_set_error(mapping, rc);
577         }
578         dout("writepages_finish %p rc %d bytes %llu wrote %d (pages)\n",
579              inode, rc, bytes, wrote);
580
581         /* clean all pages */
582         for (i = 0; i < req->r_num_pages; i++) {
583                 page = req->r_pages[i];
584                 BUG_ON(!page);
585                 WARN_ON(!PageUptodate(page));
586
587                 writeback_stat =
588                         atomic_long_dec_return(&fsc->writeback_count);
589                 if (writeback_stat <
590                     CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
591                         clear_bdi_congested(&fsc->backing_dev_info,
592                                             BLK_RW_ASYNC);
593
594                 ceph_put_snap_context((void *)page->private);
595                 page->private = 0;
596                 ClearPagePrivate(page);
597                 dout("unlocking %d %p\n", i, page);
598                 end_page_writeback(page);
599
600                 /*
601                  * We lost the cache cap, need to truncate the page before
602                  * it is unlocked, otherwise we'd truncate it later in the
603                  * page truncation thread, possibly losing some data that
604                  * raced its way in
605                  */
606                 if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0)
607                         generic_error_remove_page(inode->i_mapping, page);
608
609                 unlock_page(page);
610         }
611         dout("%p wrote+cleaned %d pages\n", inode, wrote);
612         ceph_put_wrbuffer_cap_refs(ci, req->r_num_pages, snapc);
613
614         ceph_release_pages(req->r_pages, req->r_num_pages);
615         if (req->r_pages_from_pool)
616                 mempool_free(req->r_pages,
617                              ceph_sb_to_client(inode->i_sb)->wb_pagevec_pool);
618         else
619                 kfree(req->r_pages);
620         ceph_osdc_put_request(req);
621 }
622
623 /*
624  * allocate a page vec, either directly, or if necessary, via a the
625  * mempool.  we avoid the mempool if we can because req->r_num_pages
626  * may be less than the maximum write size.
627  */
628 static void alloc_page_vec(struct ceph_fs_client *fsc,
629                            struct ceph_osd_request *req)
630 {
631         req->r_pages = kmalloc(sizeof(struct page *) * req->r_num_pages,
632                                GFP_NOFS);
633         if (!req->r_pages) {
634                 req->r_pages = mempool_alloc(fsc->wb_pagevec_pool, GFP_NOFS);
635                 req->r_pages_from_pool = 1;
636                 WARN_ON(!req->r_pages);
637         }
638 }
639
640 /*
641  * initiate async writeback
642  */
643 static int ceph_writepages_start(struct address_space *mapping,
644                                  struct writeback_control *wbc)
645 {
646         struct inode *inode = mapping->host;
647         struct ceph_inode_info *ci = ceph_inode(inode);
648         struct ceph_fs_client *fsc;
649         pgoff_t index, start, end;
650         int range_whole = 0;
651         int should_loop = 1;
652         pgoff_t max_pages = 0, max_pages_ever = 0;
653         struct ceph_snap_context *snapc = NULL, *last_snapc = NULL, *pgsnapc;
654         struct pagevec pvec;
655         int done = 0;
656         int rc = 0;
657         unsigned wsize = 1 << inode->i_blkbits;
658         struct ceph_osd_request *req = NULL;
659         int do_sync;
660         u64 snap_size = 0;
661
662         /*
663          * Include a 'sync' in the OSD request if this is a data
664          * integrity write (e.g., O_SYNC write or fsync()), or if our
665          * cap is being revoked.
666          */
667         do_sync = wbc->sync_mode == WB_SYNC_ALL;
668         if (ceph_caps_revoking(ci, CEPH_CAP_FILE_BUFFER))
669                 do_sync = 1;
670         dout("writepages_start %p dosync=%d (mode=%s)\n",
671              inode, do_sync,
672              wbc->sync_mode == WB_SYNC_NONE ? "NONE" :
673              (wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD"));
674
675         fsc = ceph_inode_to_client(inode);
676         if (fsc->mount_state == CEPH_MOUNT_SHUTDOWN) {
677                 pr_warning("writepage_start %p on forced umount\n", inode);
678                 return -EIO; /* we're in a forced umount, don't write! */
679         }
680         if (fsc->mount_options->wsize && fsc->mount_options->wsize < wsize)
681                 wsize = fsc->mount_options->wsize;
682         if (wsize < PAGE_CACHE_SIZE)
683                 wsize = PAGE_CACHE_SIZE;
684         max_pages_ever = wsize >> PAGE_CACHE_SHIFT;
685
686         pagevec_init(&pvec, 0);
687
688         /* where to start/end? */
689         if (wbc->range_cyclic) {
690                 start = mapping->writeback_index; /* Start from prev offset */
691                 end = -1;
692                 dout(" cyclic, start at %lu\n", start);
693         } else {
694                 start = wbc->range_start >> PAGE_CACHE_SHIFT;
695                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
696                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
697                         range_whole = 1;
698                 should_loop = 0;
699                 dout(" not cyclic, %lu to %lu\n", start, end);
700         }
701         index = start;
702
703 retry:
704         /* find oldest snap context with dirty data */
705         ceph_put_snap_context(snapc);
706         snapc = get_oldest_context(inode, &snap_size);
707         if (!snapc) {
708                 /* hmm, why does writepages get called when there
709                    is no dirty data? */
710                 dout(" no snap context with dirty data?\n");
711                 goto out;
712         }
713         dout(" oldest snapc is %p seq %lld (%d snaps)\n",
714              snapc, snapc->seq, snapc->num_snaps);
715         if (last_snapc && snapc != last_snapc) {
716                 /* if we switched to a newer snapc, restart our scan at the
717                  * start of the original file range. */
718                 dout("  snapc differs from last pass, restarting at %lu\n",
719                      index);
720                 index = start;
721         }
722         last_snapc = snapc;
723
724         while (!done && index <= end) {
725                 unsigned i;
726                 int first;
727                 pgoff_t next;
728                 int pvec_pages, locked_pages;
729                 struct page *page;
730                 int want;
731                 u64 offset, len;
732                 struct ceph_osd_request_head *reqhead;
733                 struct ceph_osd_op *op;
734                 long writeback_stat;
735
736                 next = 0;
737                 locked_pages = 0;
738                 max_pages = max_pages_ever;
739
740 get_more_pages:
741                 first = -1;
742                 want = min(end - index,
743                            min((pgoff_t)PAGEVEC_SIZE,
744                                max_pages - (pgoff_t)locked_pages) - 1)
745                         + 1;
746                 pvec_pages = pagevec_lookup_tag(&pvec, mapping, &index,
747                                                 PAGECACHE_TAG_DIRTY,
748                                                 want);
749                 dout("pagevec_lookup_tag got %d\n", pvec_pages);
750                 if (!pvec_pages && !locked_pages)
751                         break;
752                 for (i = 0; i < pvec_pages && locked_pages < max_pages; i++) {
753                         page = pvec.pages[i];
754                         dout("? %p idx %lu\n", page, page->index);
755                         if (locked_pages == 0)
756                                 lock_page(page);  /* first page */
757                         else if (!trylock_page(page))
758                                 break;
759
760                         /* only dirty pages, or our accounting breaks */
761                         if (unlikely(!PageDirty(page)) ||
762                             unlikely(page->mapping != mapping)) {
763                                 dout("!dirty or !mapping %p\n", page);
764                                 unlock_page(page);
765                                 break;
766                         }
767                         if (!wbc->range_cyclic && page->index > end) {
768                                 dout("end of range %p\n", page);
769                                 done = 1;
770                                 unlock_page(page);
771                                 break;
772                         }
773                         if (next && (page->index != next)) {
774                                 dout("not consecutive %p\n", page);
775                                 unlock_page(page);
776                                 break;
777                         }
778                         if (wbc->sync_mode != WB_SYNC_NONE) {
779                                 dout("waiting on writeback %p\n", page);
780                                 wait_on_page_writeback(page);
781                         }
782                         if ((snap_size && page_offset(page) > snap_size) ||
783                             (!snap_size &&
784                              page_offset(page) > i_size_read(inode))) {
785                                 dout("%p page eof %llu\n", page, snap_size ?
786                                      snap_size : i_size_read(inode));
787                                 done = 1;
788                                 unlock_page(page);
789                                 break;
790                         }
791                         if (PageWriteback(page)) {
792                                 dout("%p under writeback\n", page);
793                                 unlock_page(page);
794                                 break;
795                         }
796
797                         /* only if matching snap context */
798                         pgsnapc = (void *)page->private;
799                         if (pgsnapc->seq > snapc->seq) {
800                                 dout("page snapc %p %lld > oldest %p %lld\n",
801                                      pgsnapc, pgsnapc->seq, snapc, snapc->seq);
802                                 unlock_page(page);
803                                 if (!locked_pages)
804                                         continue; /* keep looking for snap */
805                                 break;
806                         }
807
808                         if (!clear_page_dirty_for_io(page)) {
809                                 dout("%p !clear_page_dirty_for_io\n", page);
810                                 unlock_page(page);
811                                 break;
812                         }
813
814                         /* ok */
815                         if (locked_pages == 0) {
816                                 /* prepare async write request */
817                                 offset = (unsigned long long)page->index
818                                         << PAGE_CACHE_SHIFT;
819                                 len = wsize;
820                                 req = ceph_osdc_new_request(&fsc->client->osdc,
821                                             &ci->i_layout,
822                                             ceph_vino(inode),
823                                             offset, &len,
824                                             CEPH_OSD_OP_WRITE,
825                                             CEPH_OSD_FLAG_WRITE |
826                                                     CEPH_OSD_FLAG_ONDISK,
827                                             snapc, do_sync,
828                                             ci->i_truncate_seq,
829                                             ci->i_truncate_size,
830                                             &inode->i_mtime, true, 1, 0);
831
832                                 if (!req) {
833                                         rc = -ENOMEM;
834                                         unlock_page(page);
835                                         break;
836                                 }
837
838                                 max_pages = req->r_num_pages;
839
840                                 alloc_page_vec(fsc, req);
841                                 req->r_callback = writepages_finish;
842                                 req->r_inode = inode;
843                         }
844
845                         /* note position of first page in pvec */
846                         if (first < 0)
847                                 first = i;
848                         dout("%p will write page %p idx %lu\n",
849                              inode, page, page->index);
850
851                         writeback_stat =
852                                atomic_long_inc_return(&fsc->writeback_count);
853                         if (writeback_stat > CONGESTION_ON_THRESH(
854                                     fsc->mount_options->congestion_kb)) {
855                                 set_bdi_congested(&fsc->backing_dev_info,
856                                                   BLK_RW_ASYNC);
857                         }
858
859                         set_page_writeback(page);
860                         req->r_pages[locked_pages] = page;
861                         locked_pages++;
862                         next = page->index + 1;
863                 }
864
865                 /* did we get anything? */
866                 if (!locked_pages)
867                         goto release_pvec_pages;
868                 if (i) {
869                         int j;
870                         BUG_ON(!locked_pages || first < 0);
871
872                         if (pvec_pages && i == pvec_pages &&
873                             locked_pages < max_pages) {
874                                 dout("reached end pvec, trying for more\n");
875                                 pagevec_reinit(&pvec);
876                                 goto get_more_pages;
877                         }
878
879                         /* shift unused pages over in the pvec...  we
880                          * will need to release them below. */
881                         for (j = i; j < pvec_pages; j++) {
882                                 dout(" pvec leftover page %p\n",
883                                      pvec.pages[j]);
884                                 pvec.pages[j-i+first] = pvec.pages[j];
885                         }
886                         pvec.nr -= i-first;
887                 }
888
889                 /* submit the write */
890                 offset = req->r_pages[0]->index << PAGE_CACHE_SHIFT;
891                 len = min((snap_size ? snap_size : i_size_read(inode)) - offset,
892                           (u64)locked_pages << PAGE_CACHE_SHIFT);
893                 dout("writepages got %d pages at %llu~%llu\n",
894                      locked_pages, offset, len);
895
896                 /* revise final length, page count */
897                 req->r_num_pages = locked_pages;
898                 reqhead = req->r_request->front.iov_base;
899                 op = (void *)(reqhead + 1);
900                 op->extent.length = cpu_to_le64(len);
901                 op->payload_len = cpu_to_le32(len);
902                 req->r_request->hdr.data_len = cpu_to_le32(len);
903
904                 rc = ceph_osdc_start_request(&fsc->client->osdc, req, true);
905                 BUG_ON(rc);
906                 req = NULL;
907
908                 /* continue? */
909                 index = next;
910                 wbc->nr_to_write -= locked_pages;
911                 if (wbc->nr_to_write <= 0)
912                         done = 1;
913
914 release_pvec_pages:
915                 dout("pagevec_release on %d pages (%p)\n", (int)pvec.nr,
916                      pvec.nr ? pvec.pages[0] : NULL);
917                 pagevec_release(&pvec);
918
919                 if (locked_pages && !done)
920                         goto retry;
921         }
922
923         if (should_loop && !done) {
924                 /* more to do; loop back to beginning of file */
925                 dout("writepages looping back to beginning of file\n");
926                 should_loop = 0;
927                 index = 0;
928                 goto retry;
929         }
930
931         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
932                 mapping->writeback_index = index;
933
934 out:
935         if (req)
936                 ceph_osdc_put_request(req);
937         ceph_put_snap_context(snapc);
938         dout("writepages done, rc = %d\n", rc);
939         return rc;
940 }
941
942
943
944 /*
945  * See if a given @snapc is either writeable, or already written.
946  */
947 static int context_is_writeable_or_written(struct inode *inode,
948                                            struct ceph_snap_context *snapc)
949 {
950         struct ceph_snap_context *oldest = get_oldest_context(inode, NULL);
951         int ret = !oldest || snapc->seq <= oldest->seq;
952
953         ceph_put_snap_context(oldest);
954         return ret;
955 }
956
957 /*
958  * We are only allowed to write into/dirty the page if the page is
959  * clean, or already dirty within the same snap context.
960  *
961  * called with page locked.
962  * return success with page locked,
963  * or any failure (incl -EAGAIN) with page unlocked.
964  */
965 static int ceph_update_writeable_page(struct file *file,
966                             loff_t pos, unsigned len,
967                             struct page *page)
968 {
969         struct inode *inode = file->f_dentry->d_inode;
970         struct ceph_inode_info *ci = ceph_inode(inode);
971         struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
972         loff_t page_off = pos & PAGE_CACHE_MASK;
973         int pos_in_page = pos & ~PAGE_CACHE_MASK;
974         int end_in_page = pos_in_page + len;
975         loff_t i_size;
976         int r;
977         struct ceph_snap_context *snapc, *oldest;
978
979 retry_locked:
980         /* writepages currently holds page lock, but if we change that later, */
981         wait_on_page_writeback(page);
982
983         /* check snap context */
984         BUG_ON(!ci->i_snap_realm);
985         down_read(&mdsc->snap_rwsem);
986         BUG_ON(!ci->i_snap_realm->cached_context);
987         snapc = (void *)page->private;
988         if (snapc && snapc != ci->i_head_snapc) {
989                 /*
990                  * this page is already dirty in another (older) snap
991                  * context!  is it writeable now?
992                  */
993                 oldest = get_oldest_context(inode, NULL);
994                 up_read(&mdsc->snap_rwsem);
995
996                 if (snapc->seq > oldest->seq) {
997                         ceph_put_snap_context(oldest);
998                         dout(" page %p snapc %p not current or oldest\n",
999                              page, snapc);
1000                         /*
1001                          * queue for writeback, and wait for snapc to
1002                          * be writeable or written
1003                          */
1004                         snapc = ceph_get_snap_context(snapc);
1005                         unlock_page(page);
1006                         ceph_queue_writeback(inode);
1007                         r = wait_event_interruptible(ci->i_cap_wq,
1008                                context_is_writeable_or_written(inode, snapc));
1009                         ceph_put_snap_context(snapc);
1010                         if (r == -ERESTARTSYS)
1011                                 return r;
1012                         return -EAGAIN;
1013                 }
1014                 ceph_put_snap_context(oldest);
1015
1016                 /* yay, writeable, do it now (without dropping page lock) */
1017                 dout(" page %p snapc %p not current, but oldest\n",
1018                      page, snapc);
1019                 if (!clear_page_dirty_for_io(page))
1020                         goto retry_locked;
1021                 r = writepage_nounlock(page, NULL);
1022                 if (r < 0)
1023                         goto fail_nosnap;
1024                 goto retry_locked;
1025         }
1026
1027         if (PageUptodate(page)) {
1028                 dout(" page %p already uptodate\n", page);
1029                 return 0;
1030         }
1031
1032         /* full page? */
1033         if (pos_in_page == 0 && len == PAGE_CACHE_SIZE)
1034                 return 0;
1035
1036         /* past end of file? */
1037         i_size = inode->i_size;   /* caller holds i_mutex */
1038
1039         if (i_size + len > inode->i_sb->s_maxbytes) {
1040                 /* file is too big */
1041                 r = -EINVAL;
1042                 goto fail;
1043         }
1044
1045         if (page_off >= i_size ||
1046             (pos_in_page == 0 && (pos+len) >= i_size &&
1047              end_in_page - pos_in_page != PAGE_CACHE_SIZE)) {
1048                 dout(" zeroing %p 0 - %d and %d - %d\n",
1049                      page, pos_in_page, end_in_page, (int)PAGE_CACHE_SIZE);
1050                 zero_user_segments(page,
1051                                    0, pos_in_page,
1052                                    end_in_page, PAGE_CACHE_SIZE);
1053                 return 0;
1054         }
1055
1056         /* we need to read it. */
1057         up_read(&mdsc->snap_rwsem);
1058         r = readpage_nounlock(file, page);
1059         if (r < 0)
1060                 goto fail_nosnap;
1061         goto retry_locked;
1062
1063 fail:
1064         up_read(&mdsc->snap_rwsem);
1065 fail_nosnap:
1066         unlock_page(page);
1067         return r;
1068 }
1069
1070 /*
1071  * We are only allowed to write into/dirty the page if the page is
1072  * clean, or already dirty within the same snap context.
1073  */
1074 static int ceph_write_begin(struct file *file, struct address_space *mapping,
1075                             loff_t pos, unsigned len, unsigned flags,
1076                             struct page **pagep, void **fsdata)
1077 {
1078         struct inode *inode = file->f_dentry->d_inode;
1079         struct page *page;
1080         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1081         int r;
1082
1083         do {
1084                 /* get a page */
1085                 page = grab_cache_page_write_begin(mapping, index, 0);
1086                 if (!page)
1087                         return -ENOMEM;
1088                 *pagep = page;
1089
1090                 dout("write_begin file %p inode %p page %p %d~%d\n", file,
1091                      inode, page, (int)pos, (int)len);
1092
1093                 r = ceph_update_writeable_page(file, pos, len, page);
1094         } while (r == -EAGAIN);
1095
1096         return r;
1097 }
1098
1099 /*
1100  * we don't do anything in here that simple_write_end doesn't do
1101  * except adjust dirty page accounting and drop read lock on
1102  * mdsc->snap_rwsem.
1103  */
1104 static int ceph_write_end(struct file *file, struct address_space *mapping,
1105                           loff_t pos, unsigned len, unsigned copied,
1106                           struct page *page, void *fsdata)
1107 {
1108         struct inode *inode = file->f_dentry->d_inode;
1109         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
1110         struct ceph_mds_client *mdsc = fsc->mdsc;
1111         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1112         int check_cap = 0;
1113
1114         dout("write_end file %p inode %p page %p %d~%d (%d)\n", file,
1115              inode, page, (int)pos, (int)copied, (int)len);
1116
1117         /* zero the stale part of the page if we did a short copy */
1118         if (copied < len)
1119                 zero_user_segment(page, from+copied, len);
1120
1121         /* did file size increase? */
1122         /* (no need for i_size_read(); we caller holds i_mutex */
1123         if (pos+copied > inode->i_size)
1124                 check_cap = ceph_inode_set_size(inode, pos+copied);
1125
1126         if (!PageUptodate(page))
1127                 SetPageUptodate(page);
1128
1129         set_page_dirty(page);
1130
1131         unlock_page(page);
1132         up_read(&mdsc->snap_rwsem);
1133         page_cache_release(page);
1134
1135         if (check_cap)
1136                 ceph_check_caps(ceph_inode(inode), CHECK_CAPS_AUTHONLY, NULL);
1137
1138         return copied;
1139 }
1140
1141 /*
1142  * we set .direct_IO to indicate direct io is supported, but since we
1143  * intercept O_DIRECT reads and writes early, this function should
1144  * never get called.
1145  */
1146 static ssize_t ceph_direct_io(int rw, struct kiocb *iocb,
1147                               const struct iovec *iov,
1148                               loff_t pos, unsigned long nr_segs)
1149 {
1150         WARN_ON(1);
1151         return -EINVAL;
1152 }
1153
1154 const struct address_space_operations ceph_aops = {
1155         .readpage = ceph_readpage,
1156         .readpages = ceph_readpages,
1157         .writepage = ceph_writepage,
1158         .writepages = ceph_writepages_start,
1159         .write_begin = ceph_write_begin,
1160         .write_end = ceph_write_end,
1161         .set_page_dirty = ceph_set_page_dirty,
1162         .invalidatepage = ceph_invalidatepage,
1163         .releasepage = ceph_releasepage,
1164         .direct_IO = ceph_direct_io,
1165 };
1166
1167
1168 /*
1169  * vm ops
1170  */
1171
1172 /*
1173  * Reuse write_begin here for simplicity.
1174  */
1175 static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
1176 {
1177         struct inode *inode = vma->vm_file->f_dentry->d_inode;
1178         struct page *page = vmf->page;
1179         struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
1180         loff_t off = page->index << PAGE_CACHE_SHIFT;
1181         loff_t size, len;
1182         int ret;
1183
1184         size = i_size_read(inode);
1185         if (off + PAGE_CACHE_SIZE <= size)
1186                 len = PAGE_CACHE_SIZE;
1187         else
1188                 len = size & ~PAGE_CACHE_MASK;
1189
1190         dout("page_mkwrite %p %llu~%llu page %p idx %lu\n", inode,
1191              off, len, page, page->index);
1192
1193         lock_page(page);
1194
1195         ret = VM_FAULT_NOPAGE;
1196         if ((off > size) ||
1197             (page->mapping != inode->i_mapping))
1198                 goto out;
1199
1200         ret = ceph_update_writeable_page(vma->vm_file, off, len, page);
1201         if (ret == 0) {
1202                 /* success.  we'll keep the page locked. */
1203                 set_page_dirty(page);
1204                 up_read(&mdsc->snap_rwsem);
1205                 ret = VM_FAULT_LOCKED;
1206         } else {
1207                 if (ret == -ENOMEM)
1208                         ret = VM_FAULT_OOM;
1209                 else
1210                         ret = VM_FAULT_SIGBUS;
1211         }
1212 out:
1213         dout("page_mkwrite %p %llu~%llu = %d\n", inode, off, len, ret);
1214         if (ret != VM_FAULT_LOCKED)
1215                 unlock_page(page);
1216         return ret;
1217 }
1218
1219 static struct vm_operations_struct ceph_vmops = {
1220         .fault          = filemap_fault,
1221         .page_mkwrite   = ceph_page_mkwrite,
1222 };
1223
1224 int ceph_mmap(struct file *file, struct vm_area_struct *vma)
1225 {
1226         struct address_space *mapping = file->f_mapping;
1227
1228         if (!mapping->a_ops->readpage)
1229                 return -ENOEXEC;
1230         file_accessed(file);
1231         vma->vm_ops = &ceph_vmops;
1232         vma->vm_flags |= VM_CAN_NONLINEAR;
1233         return 0;
1234 }