1 /* handling of writes to regular files and writing back to the server
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
12 #include <linux/backing-dev.h>
13 #include <linux/slab.h>
15 #include <linux/pagemap.h>
16 #include <linux/writeback.h>
17 #include <linux/pagevec.h>
21 * mark a page as having been made dirty and thus needing writeback
23 int afs_set_page_dirty(struct page *page)
26 return __set_page_dirty_nobuffers(page);
30 * partly or wholly fill a page that's under preparation for writing
32 static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
33 loff_t pos, unsigned int len, struct page *page)
40 _enter(",,%llu", (unsigned long long)pos);
42 if (pos >= vnode->vfs_inode.i_size) {
44 ASSERTCMP(p + len, <=, PAGE_SIZE);
46 memset(data + p, 0, len);
51 req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *),
56 refcount_set(&req->usage, 1);
60 req->pages = req->array;
64 ret = afs_fetch_data(vnode, key, req);
68 _debug("got NOENT from server"
69 " - marking file deleted and stale");
70 set_bit(AFS_VNODE_DELETED, &vnode->flags);
80 * prepare to perform part of a write to a page
82 int afs_write_begin(struct file *file, struct address_space *mapping,
83 loff_t pos, unsigned len, unsigned flags,
84 struct page **pagep, void **fsdata)
86 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
88 struct key *key = afs_file_key(file);
90 unsigned f, from = pos & (PAGE_SIZE - 1);
91 unsigned t, to = from + len;
92 pgoff_t index = pos >> PAGE_SHIFT;
95 _enter("{%llx:%llu},{%lx},%u,%u",
96 vnode->fid.vid, vnode->fid.vnode, index, from, to);
98 /* We want to store information about how much of a page is altered in
101 BUILD_BUG_ON(PAGE_SIZE > 32768 && sizeof(page->private) < 8);
103 page = grab_cache_page_write_begin(mapping, index, flags);
107 if (!PageUptodate(page) && len != PAGE_SIZE) {
108 ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page);
112 _leave(" = %d [prep]", ret);
115 SetPageUptodate(page);
118 /* page won't leak in error case: it eventually gets cleaned off LRU */
122 /* See if this page is already partially written in a way that we can
123 * merge the new write with.
126 if (PagePrivate(page)) {
127 priv = page_private(page);
128 f = priv & AFS_PRIV_MAX;
129 t = priv >> AFS_PRIV_SHIFT;
134 if (PageWriteback(page)) {
135 trace_afs_page_dirty(vnode, tracepoint_string("alrdy"),
137 goto flush_conflicting_write;
139 /* If the file is being filled locally, allow inter-write
140 * spaces to be merged into writes. If it's not, only write
141 * back what the user gives us.
143 if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
144 (to < f || from > t))
145 goto flush_conflicting_write;
155 priv = (unsigned long)t << AFS_PRIV_SHIFT;
157 trace_afs_page_dirty(vnode, tracepoint_string("begin"),
159 SetPagePrivate(page);
160 set_page_private(page, priv);
164 /* The previous write and this write aren't adjacent or overlapping, so
165 * flush the page out.
167 flush_conflicting_write:
168 _debug("flush conflict");
169 ret = write_one_page(page);
171 _leave(" = %d", ret);
175 ret = lock_page_killable(page);
177 _leave(" = %d", ret);
184 * finalise part of a write to a page
186 int afs_write_end(struct file *file, struct address_space *mapping,
187 loff_t pos, unsigned len, unsigned copied,
188 struct page *page, void *fsdata)
190 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
191 struct key *key = afs_file_key(file);
192 loff_t i_size, maybe_i_size;
195 _enter("{%llx:%llu},{%lx}",
196 vnode->fid.vid, vnode->fid.vnode, page->index);
198 maybe_i_size = pos + copied;
200 i_size = i_size_read(&vnode->vfs_inode);
201 if (maybe_i_size > i_size) {
202 spin_lock(&vnode->wb_lock);
203 i_size = i_size_read(&vnode->vfs_inode);
204 if (maybe_i_size > i_size)
205 i_size_write(&vnode->vfs_inode, maybe_i_size);
206 spin_unlock(&vnode->wb_lock);
209 if (!PageUptodate(page)) {
211 /* Try and load any missing data from the server. The
212 * unmarshalling routine will take care of clearing any
213 * bits that are beyond the EOF.
215 ret = afs_fill_page(vnode, key, pos + copied,
220 SetPageUptodate(page);
223 set_page_dirty(page);
235 * kill all the pages in the given range
237 static void afs_kill_pages(struct address_space *mapping,
238 pgoff_t first, pgoff_t last)
240 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
242 unsigned count, loop;
244 _enter("{%llx:%llu},%lx-%lx",
245 vnode->fid.vid, vnode->fid.vnode, first, last);
250 _debug("kill %lx-%lx", first, last);
252 count = last - first + 1;
253 if (count > PAGEVEC_SIZE)
254 count = PAGEVEC_SIZE;
255 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
256 ASSERTCMP(pv.nr, ==, count);
258 for (loop = 0; loop < count; loop++) {
259 struct page *page = pv.pages[loop];
260 ClearPageUptodate(page);
262 end_page_writeback(page);
263 if (page->index >= first)
264 first = page->index + 1;
266 generic_error_remove_page(mapping, page);
270 __pagevec_release(&pv);
271 } while (first <= last);
277 * Redirty all the pages in a given range.
279 static void afs_redirty_pages(struct writeback_control *wbc,
280 struct address_space *mapping,
281 pgoff_t first, pgoff_t last)
283 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
285 unsigned count, loop;
287 _enter("{%llx:%llu},%lx-%lx",
288 vnode->fid.vid, vnode->fid.vnode, first, last);
293 _debug("redirty %lx-%lx", first, last);
295 count = last - first + 1;
296 if (count > PAGEVEC_SIZE)
297 count = PAGEVEC_SIZE;
298 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
299 ASSERTCMP(pv.nr, ==, count);
301 for (loop = 0; loop < count; loop++) {
302 struct page *page = pv.pages[loop];
304 redirty_page_for_writepage(wbc, page);
305 end_page_writeback(page);
306 if (page->index >= first)
307 first = page->index + 1;
310 __pagevec_release(&pv);
311 } while (first <= last);
319 static int afs_store_data(struct address_space *mapping,
320 pgoff_t first, pgoff_t last,
321 unsigned offset, unsigned to)
323 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
324 struct afs_fs_cursor fc;
325 struct afs_wb_key *wbk = NULL;
327 int ret = -ENOKEY, ret2;
329 _enter("%s{%llx:%llu.%u},%lx,%lx,%x,%x",
334 first, last, offset, to);
336 spin_lock(&vnode->wb_lock);
337 p = vnode->wb_keys.next;
339 /* Iterate through the list looking for a valid key to use. */
341 while (p != &vnode->wb_keys) {
342 wbk = list_entry(p, struct afs_wb_key, vnode_link);
343 _debug("wbk %u", key_serial(wbk->key));
344 ret2 = key_validate(wbk->key);
352 spin_unlock(&vnode->wb_lock);
354 _leave(" = %d [no keys]", ret);
358 refcount_inc(&wbk->usage);
359 spin_unlock(&vnode->wb_lock);
361 _debug("USE WB KEY %u", key_serial(wbk->key));
364 if (afs_begin_vnode_operation(&fc, vnode, wbk->key)) {
365 while (afs_select_fileserver(&fc)) {
366 fc.cb_break = afs_calc_vnode_cb_break(vnode);
367 afs_fs_store_data(&fc, mapping, first, last, offset, to);
370 afs_check_for_remote_deletion(&fc, fc.vnode);
371 afs_vnode_commit_status(&fc, vnode, fc.cb_break);
372 ret = afs_end_vnode_operation(&fc);
377 afs_stat_v(vnode, n_stores);
378 atomic_long_add((last * PAGE_SIZE + to) -
379 (first * PAGE_SIZE + offset),
380 &afs_v2net(vnode)->n_store_bytes);
389 spin_lock(&vnode->wb_lock);
390 p = wbk->vnode_link.next;
396 _leave(" = %d", ret);
401 * Synchronously write back the locked page and any subsequent non-locked dirty
404 static int afs_write_back_from_locked_page(struct address_space *mapping,
405 struct writeback_control *wbc,
406 struct page *primary_page,
409 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
410 struct page *pages[8], *page;
411 unsigned long count, priv;
412 unsigned n, offset, to, f, t;
413 pgoff_t start, first, last;
416 _enter(",%lx", primary_page->index);
419 if (test_set_page_writeback(primary_page))
422 /* Find all consecutive lockable dirty pages that have contiguous
423 * written regions, stopping when we find a page that is not
424 * immediately lockable, is not dirty or is missing, or we reach the
427 start = primary_page->index;
428 priv = page_private(primary_page);
429 offset = priv & AFS_PRIV_MAX;
430 to = priv >> AFS_PRIV_SHIFT;
431 trace_afs_page_dirty(vnode, tracepoint_string("store"),
432 primary_page->index, priv);
434 WARN_ON(offset == to);
436 trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
437 primary_page->index, priv);
439 if (start >= final_page ||
440 (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)))
445 _debug("more %lx [%lx]", start, count);
446 n = final_page - start + 1;
447 if (n > ARRAY_SIZE(pages))
448 n = ARRAY_SIZE(pages);
449 n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages);
450 _debug("fgpc %u", n);
453 if (pages[0]->index != start) {
455 put_page(pages[--n]);
460 for (loop = 0; loop < n; loop++) {
462 if (to != PAGE_SIZE &&
463 !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags))
465 if (page->index > final_page)
467 if (!trylock_page(page))
469 if (!PageDirty(page) || PageWriteback(page)) {
474 priv = page_private(page);
475 f = priv & AFS_PRIV_MAX;
476 t = priv >> AFS_PRIV_SHIFT;
478 !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) {
484 trace_afs_page_dirty(vnode, tracepoint_string("store+"),
487 if (!clear_page_dirty_for_io(page))
489 if (test_set_page_writeback(page))
496 for (; loop < n; loop++)
497 put_page(pages[loop]);
502 } while (start <= final_page && count < 65536);
505 /* We now have a contiguous set of dirty pages, each with writeback
506 * set; the first page is still locked at this point, but all the rest
507 * have been unlocked.
509 unlock_page(primary_page);
511 first = primary_page->index;
512 last = first + count - 1;
514 _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
516 ret = afs_store_data(mapping, first, last, offset, to);
523 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
531 afs_redirty_pages(wbc, mapping, first, last);
532 mapping_set_error(mapping, ret);
537 afs_redirty_pages(wbc, mapping, first, last);
538 mapping_set_error(mapping, -ENOSPC);
548 trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
549 afs_kill_pages(mapping, first, last);
550 mapping_set_error(mapping, ret);
554 _leave(" = %d", ret);
559 * write a page back to the server
560 * - the caller locked the page for us
562 int afs_writepage(struct page *page, struct writeback_control *wbc)
566 _enter("{%lx},", page->index);
568 ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
569 wbc->range_end >> PAGE_SHIFT);
571 _leave(" = %d", ret);
575 wbc->nr_to_write -= ret;
582 * write a region of pages back to the server
584 static int afs_writepages_region(struct address_space *mapping,
585 struct writeback_control *wbc,
586 pgoff_t index, pgoff_t end, pgoff_t *_next)
591 _enter(",,%lx,%lx,", index, end);
594 n = find_get_pages_range_tag(mapping, &index, end,
595 PAGECACHE_TAG_DIRTY, 1, &page);
599 _debug("wback %lx", page->index);
602 * at this point we hold neither the i_pages lock nor the
603 * page lock: the page may be truncated or invalidated
604 * (changing page->mapping to NULL), or even swizzled
605 * back from swapper_space to tmpfs file mapping
607 ret = lock_page_killable(page);
610 _leave(" = %d", ret);
614 if (page->mapping != mapping || !PageDirty(page)) {
620 if (PageWriteback(page)) {
622 if (wbc->sync_mode != WB_SYNC_NONE)
623 wait_on_page_writeback(page);
628 if (!clear_page_dirty_for_io(page))
630 ret = afs_write_back_from_locked_page(mapping, wbc, page, end);
633 _leave(" = %d", ret);
637 wbc->nr_to_write -= ret;
640 } while (index < end && wbc->nr_to_write > 0);
643 _leave(" = 0 [%lx]", *_next);
648 * write some of the pending data back to the server
650 int afs_writepages(struct address_space *mapping,
651 struct writeback_control *wbc)
653 pgoff_t start, end, next;
658 if (wbc->range_cyclic) {
659 start = mapping->writeback_index;
661 ret = afs_writepages_region(mapping, wbc, start, end, &next);
662 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
663 ret = afs_writepages_region(mapping, wbc, 0, start,
665 mapping->writeback_index = next;
666 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
667 end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT);
668 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
669 if (wbc->nr_to_write > 0)
670 mapping->writeback_index = next;
672 start = wbc->range_start >> PAGE_SHIFT;
673 end = wbc->range_end >> PAGE_SHIFT;
674 ret = afs_writepages_region(mapping, wbc, start, end, &next);
677 _leave(" = %d", ret);
682 * completion of write to server
684 void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
688 unsigned count, loop;
689 pgoff_t first = call->first, last = call->last;
691 _enter("{%llx:%llu},{%lx-%lx}",
692 vnode->fid.vid, vnode->fid.vnode, first, last);
697 _debug("done %lx-%lx", first, last);
699 count = last - first + 1;
700 if (count > PAGEVEC_SIZE)
701 count = PAGEVEC_SIZE;
702 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
703 first, count, pv.pages);
704 ASSERTCMP(pv.nr, ==, count);
706 for (loop = 0; loop < count; loop++) {
707 priv = page_private(pv.pages[loop]);
708 trace_afs_page_dirty(vnode, tracepoint_string("clear"),
709 pv.pages[loop]->index, priv);
710 set_page_private(pv.pages[loop], 0);
711 end_page_writeback(pv.pages[loop]);
714 __pagevec_release(&pv);
715 } while (first <= last);
717 afs_prune_wb_keys(vnode);
722 * write to an AFS file
724 ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
726 struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
728 size_t count = iov_iter_count(from);
730 _enter("{%llx:%llu},{%zu},",
731 vnode->fid.vid, vnode->fid.vnode, count);
733 if (IS_SWAPFILE(&vnode->vfs_inode)) {
735 "AFS: Attempt to write to active swap file!\n");
742 result = generic_file_write_iter(iocb, from);
744 _leave(" = %zd", result);
749 * flush any dirty pages for this process, and check for write errors.
750 * - the return status from this call provides a reliable indication of
751 * whether any write errors occurred for this process.
753 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
755 struct inode *inode = file_inode(file);
756 struct afs_vnode *vnode = AFS_FS_I(inode);
758 _enter("{%llx:%llu},{n=%pD},%d",
759 vnode->fid.vid, vnode->fid.vnode, file,
762 return file_write_and_wait_range(file, start, end);
766 * notification that a previously read-only page is about to become writable
767 * - if it returns an error, the caller will deliver a bus error signal
769 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
771 struct file *file = vmf->vma->vm_file;
772 struct inode *inode = file_inode(file);
773 struct afs_vnode *vnode = AFS_FS_I(inode);
776 _enter("{{%llx:%llu}},{%lx}",
777 vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
779 sb_start_pagefault(inode->i_sb);
781 /* Wait for the page to be written to the cache before we allow it to
782 * be modified. We then assume the entire page will need writing back.
784 #ifdef CONFIG_AFS_FSCACHE
785 fscache_wait_on_page_write(vnode->cache, vmf->page);
788 if (PageWriteback(vmf->page) &&
789 wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
790 return VM_FAULT_RETRY;
792 if (lock_page_killable(vmf->page) < 0)
793 return VM_FAULT_RETRY;
795 /* We mustn't change page->private until writeback is complete as that
796 * details the portion of the page we need to write back and we might
797 * need to redirty the page if there's a problem.
799 wait_on_page_writeback(vmf->page);
801 priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
802 priv |= 0; /* From */
803 trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
804 vmf->page->index, priv);
805 SetPagePrivate(vmf->page);
806 set_page_private(vmf->page, priv);
808 sb_end_pagefault(inode->i_sb);
809 return VM_FAULT_LOCKED;
813 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
815 void afs_prune_wb_keys(struct afs_vnode *vnode)
817 LIST_HEAD(graveyard);
818 struct afs_wb_key *wbk, *tmp;
820 /* Discard unused keys */
821 spin_lock(&vnode->wb_lock);
823 if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
824 !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
825 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
826 if (refcount_read(&wbk->usage) == 1)
827 list_move(&wbk->vnode_link, &graveyard);
831 spin_unlock(&vnode->wb_lock);
833 while (!list_empty(&graveyard)) {
834 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
835 list_del(&wbk->vnode_link);
841 * Clean up a page during invalidation.
843 int afs_launder_page(struct page *page)
845 struct address_space *mapping = page->mapping;
846 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
851 _enter("{%lx}", page->index);
853 priv = page_private(page);
854 if (clear_page_dirty_for_io(page)) {
857 if (PagePrivate(page)) {
858 f = priv & AFS_PRIV_MAX;
859 t = priv >> AFS_PRIV_SHIFT;
862 trace_afs_page_dirty(vnode, tracepoint_string("launder"),
864 ret = afs_store_data(mapping, page->index, page->index, t, f);
867 trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
869 set_page_private(page, 0);
870 ClearPagePrivate(page);
872 #ifdef CONFIG_AFS_FSCACHE
873 if (PageFsCache(page)) {
874 fscache_wait_on_page_write(vnode->cache, page);
875 fscache_uncache_page(vnode->cache, page);