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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* handling of writes to regular files and writing back to the server
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/backing-dev.h>
9#include <linux/slab.h>
10#include <linux/fs.h>
11#include <linux/pagemap.h>
12#include <linux/writeback.h>
13#include <linux/pagevec.h>
14#include <linux/netfs.h>
15#include <trace/events/netfs.h>
16#include "internal.h"
17
18/*
19 * completion of write to server
20 */
21static void afs_pages_written_back(struct afs_vnode *vnode, loff_t start, unsigned int len)
22{
23 _enter("{%llx:%llu},{%x @%llx}",
24 vnode->fid.vid, vnode->fid.vnode, len, start);
25
26 afs_prune_wb_keys(vnode);
27 _leave("");
28}
29
30/*
31 * Find a key to use for the writeback. We cached the keys used to author the
32 * writes on the vnode. *_wbk will contain the last writeback key used or NULL
33 * and we need to start from there if it's set.
34 */
35static int afs_get_writeback_key(struct afs_vnode *vnode,
36 struct afs_wb_key **_wbk)
37{
38 struct afs_wb_key *wbk = NULL;
39 struct list_head *p;
40 int ret = -ENOKEY, ret2;
41
42 spin_lock(&vnode->wb_lock);
43 if (*_wbk)
44 p = (*_wbk)->vnode_link.next;
45 else
46 p = vnode->wb_keys.next;
47
48 while (p != &vnode->wb_keys) {
49 wbk = list_entry(p, struct afs_wb_key, vnode_link);
50 _debug("wbk %u", key_serial(wbk->key));
51 ret2 = key_validate(wbk->key);
52 if (ret2 == 0) {
53 refcount_inc(&wbk->usage);
54 _debug("USE WB KEY %u", key_serial(wbk->key));
55 break;
56 }
57
58 wbk = NULL;
59 if (ret == -ENOKEY)
60 ret = ret2;
61 p = p->next;
62 }
63
64 spin_unlock(&vnode->wb_lock);
65 if (*_wbk)
66 afs_put_wb_key(*_wbk);
67 *_wbk = wbk;
68 return 0;
69}
70
71static void afs_store_data_success(struct afs_operation *op)
72{
73 struct afs_vnode *vnode = op->file[0].vnode;
74
75 op->ctime = op->file[0].scb.status.mtime_client;
76 afs_vnode_commit_status(op, &op->file[0]);
77 if (!afs_op_error(op)) {
78 if (!op->store.laundering)
79 afs_pages_written_back(vnode, op->store.pos, op->store.size);
80 afs_stat_v(vnode, n_stores);
81 atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
82 }
83}
84
85static const struct afs_operation_ops afs_store_data_operation = {
86 .issue_afs_rpc = afs_fs_store_data,
87 .issue_yfs_rpc = yfs_fs_store_data,
88 .success = afs_store_data_success,
89};
90
91/*
92 * write to a file
93 */
94static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t pos,
95 bool laundering)
96{
97 struct afs_operation *op;
98 struct afs_wb_key *wbk = NULL;
99 loff_t size = iov_iter_count(iter);
100 int ret = -ENOKEY;
101
102 _enter("%s{%llx:%llu.%u},%llx,%llx",
103 vnode->volume->name,
104 vnode->fid.vid,
105 vnode->fid.vnode,
106 vnode->fid.unique,
107 size, pos);
108
109 ret = afs_get_writeback_key(vnode, &wbk);
110 if (ret) {
111 _leave(" = %d [no keys]", ret);
112 return ret;
113 }
114
115 op = afs_alloc_operation(wbk->key, vnode->volume);
116 if (IS_ERR(op)) {
117 afs_put_wb_key(wbk);
118 return -ENOMEM;
119 }
120
121 afs_op_set_vnode(op, 0, vnode);
122 op->file[0].dv_delta = 1;
123 op->file[0].modification = true;
124 op->store.pos = pos;
125 op->store.size = size;
126 op->store.laundering = laundering;
127 op->flags |= AFS_OPERATION_UNINTR;
128 op->ops = &afs_store_data_operation;
129
130try_next_key:
131 afs_begin_vnode_operation(op);
132
133 op->store.write_iter = iter;
134 op->store.i_size = max(pos + size, vnode->netfs.remote_i_size);
135 op->mtime = inode_get_mtime(&vnode->netfs.inode);
136
137 afs_wait_for_operation(op);
138
139 switch (afs_op_error(op)) {
140 case -EACCES:
141 case -EPERM:
142 case -ENOKEY:
143 case -EKEYEXPIRED:
144 case -EKEYREJECTED:
145 case -EKEYREVOKED:
146 _debug("next");
147
148 ret = afs_get_writeback_key(vnode, &wbk);
149 if (ret == 0) {
150 key_put(op->key);
151 op->key = key_get(wbk->key);
152 goto try_next_key;
153 }
154 break;
155 }
156
157 afs_put_wb_key(wbk);
158 _leave(" = %d", afs_op_error(op));
159 return afs_put_operation(op);
160}
161
162static void afs_upload_to_server(struct netfs_io_subrequest *subreq)
163{
164 struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode);
165 ssize_t ret;
166
167 _enter("%x[%x],%zx",
168 subreq->rreq->debug_id, subreq->debug_index, subreq->io_iter.count);
169
170 trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
171 ret = afs_store_data(vnode, &subreq->io_iter, subreq->start,
172 subreq->rreq->origin == NETFS_LAUNDER_WRITE);
173 netfs_write_subrequest_terminated(subreq, ret < 0 ? ret : subreq->len,
174 false);
175}
176
177static void afs_upload_to_server_worker(struct work_struct *work)
178{
179 struct netfs_io_subrequest *subreq =
180 container_of(work, struct netfs_io_subrequest, work);
181
182 afs_upload_to_server(subreq);
183}
184
185/*
186 * Set up write requests for a writeback slice. We need to add a write request
187 * for each write we want to make.
188 */
189void afs_create_write_requests(struct netfs_io_request *wreq, loff_t start, size_t len)
190{
191 struct netfs_io_subrequest *subreq;
192
193 _enter("%x,%llx-%llx", wreq->debug_id, start, start + len);
194
195 subreq = netfs_create_write_request(wreq, NETFS_UPLOAD_TO_SERVER,
196 start, len, afs_upload_to_server_worker);
197 if (subreq)
198 netfs_queue_write_request(subreq);
199}
200
201/*
202 * write some of the pending data back to the server
203 */
204int afs_writepages(struct address_space *mapping, struct writeback_control *wbc)
205{
206 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
207 int ret;
208
209 /* We have to be careful as we can end up racing with setattr()
210 * truncating the pagecache since the caller doesn't take a lock here
211 * to prevent it.
212 */
213 if (wbc->sync_mode == WB_SYNC_ALL)
214 down_read(&vnode->validate_lock);
215 else if (!down_read_trylock(&vnode->validate_lock))
216 return 0;
217
218 ret = netfs_writepages(mapping, wbc);
219 up_read(&vnode->validate_lock);
220 return ret;
221}
222
223/*
224 * flush any dirty pages for this process, and check for write errors.
225 * - the return status from this call provides a reliable indication of
226 * whether any write errors occurred for this process.
227 */
228int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
229{
230 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
231 struct afs_file *af = file->private_data;
232 int ret;
233
234 _enter("{%llx:%llu},{n=%pD},%d",
235 vnode->fid.vid, vnode->fid.vnode, file,
236 datasync);
237
238 ret = afs_validate(vnode, af->key);
239 if (ret < 0)
240 return ret;
241
242 return file_write_and_wait_range(file, start, end);
243}
244
245/*
246 * notification that a previously read-only page is about to become writable
247 * - if it returns an error, the caller will deliver a bus error signal
248 */
249vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
250{
251 struct file *file = vmf->vma->vm_file;
252
253 if (afs_validate(AFS_FS_I(file_inode(file)), afs_file_key(file)) < 0)
254 return VM_FAULT_SIGBUS;
255 return netfs_page_mkwrite(vmf, NULL);
256}
257
258/*
259 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
260 */
261void afs_prune_wb_keys(struct afs_vnode *vnode)
262{
263 LIST_HEAD(graveyard);
264 struct afs_wb_key *wbk, *tmp;
265
266 /* Discard unused keys */
267 spin_lock(&vnode->wb_lock);
268
269 if (!mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
270 !mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_DIRTY)) {
271 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
272 if (refcount_read(&wbk->usage) == 1)
273 list_move(&wbk->vnode_link, &graveyard);
274 }
275 }
276
277 spin_unlock(&vnode->wb_lock);
278
279 while (!list_empty(&graveyard)) {
280 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
281 list_del(&wbk->vnode_link);
282 afs_put_wb_key(wbk);
283 }
284}
1/* handling of writes to regular files and writing back to the server
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
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.
10 */
11#include <linux/backing-dev.h>
12#include <linux/slab.h>
13#include <linux/fs.h>
14#include <linux/pagemap.h>
15#include <linux/writeback.h>
16#include <linux/pagevec.h>
17#include <linux/aio.h>
18#include "internal.h"
19
20static int afs_write_back_from_locked_page(struct afs_writeback *wb,
21 struct page *page);
22
23/*
24 * mark a page as having been made dirty and thus needing writeback
25 */
26int afs_set_page_dirty(struct page *page)
27{
28 _enter("");
29 return __set_page_dirty_nobuffers(page);
30}
31
32/*
33 * unlink a writeback record because its usage has reached zero
34 * - must be called with the wb->vnode->writeback_lock held
35 */
36static void afs_unlink_writeback(struct afs_writeback *wb)
37{
38 struct afs_writeback *front;
39 struct afs_vnode *vnode = wb->vnode;
40
41 list_del_init(&wb->link);
42 if (!list_empty(&vnode->writebacks)) {
43 /* if an fsync rises to the front of the queue then wake it
44 * up */
45 front = list_entry(vnode->writebacks.next,
46 struct afs_writeback, link);
47 if (front->state == AFS_WBACK_SYNCING) {
48 _debug("wake up sync");
49 front->state = AFS_WBACK_COMPLETE;
50 wake_up(&front->waitq);
51 }
52 }
53}
54
55/*
56 * free a writeback record
57 */
58static void afs_free_writeback(struct afs_writeback *wb)
59{
60 _enter("");
61 key_put(wb->key);
62 kfree(wb);
63}
64
65/*
66 * dispose of a reference to a writeback record
67 */
68void afs_put_writeback(struct afs_writeback *wb)
69{
70 struct afs_vnode *vnode = wb->vnode;
71
72 _enter("{%d}", wb->usage);
73
74 spin_lock(&vnode->writeback_lock);
75 if (--wb->usage == 0)
76 afs_unlink_writeback(wb);
77 else
78 wb = NULL;
79 spin_unlock(&vnode->writeback_lock);
80 if (wb)
81 afs_free_writeback(wb);
82}
83
84/*
85 * partly or wholly fill a page that's under preparation for writing
86 */
87static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
88 loff_t pos, struct page *page)
89{
90 loff_t i_size;
91 int ret;
92 int len;
93
94 _enter(",,%llu", (unsigned long long)pos);
95
96 i_size = i_size_read(&vnode->vfs_inode);
97 if (pos + PAGE_CACHE_SIZE > i_size)
98 len = i_size - pos;
99 else
100 len = PAGE_CACHE_SIZE;
101
102 ret = afs_vnode_fetch_data(vnode, key, pos, len, page);
103 if (ret < 0) {
104 if (ret == -ENOENT) {
105 _debug("got NOENT from server"
106 " - marking file deleted and stale");
107 set_bit(AFS_VNODE_DELETED, &vnode->flags);
108 ret = -ESTALE;
109 }
110 }
111
112 _leave(" = %d", ret);
113 return ret;
114}
115
116/*
117 * prepare to perform part of a write to a page
118 */
119int afs_write_begin(struct file *file, struct address_space *mapping,
120 loff_t pos, unsigned len, unsigned flags,
121 struct page **pagep, void **fsdata)
122{
123 struct afs_writeback *candidate, *wb;
124 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
125 struct page *page;
126 struct key *key = file->private_data;
127 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
128 unsigned to = from + len;
129 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
130 int ret;
131
132 _enter("{%x:%u},{%lx},%u,%u",
133 vnode->fid.vid, vnode->fid.vnode, index, from, to);
134
135 candidate = kzalloc(sizeof(*candidate), GFP_KERNEL);
136 if (!candidate)
137 return -ENOMEM;
138 candidate->vnode = vnode;
139 candidate->first = candidate->last = index;
140 candidate->offset_first = from;
141 candidate->to_last = to;
142 INIT_LIST_HEAD(&candidate->link);
143 candidate->usage = 1;
144 candidate->state = AFS_WBACK_PENDING;
145 init_waitqueue_head(&candidate->waitq);
146
147 page = grab_cache_page_write_begin(mapping, index, flags);
148 if (!page) {
149 kfree(candidate);
150 return -ENOMEM;
151 }
152 *pagep = page;
153 /* page won't leak in error case: it eventually gets cleaned off LRU */
154
155 if (!PageUptodate(page) && len != PAGE_CACHE_SIZE) {
156 ret = afs_fill_page(vnode, key, index << PAGE_CACHE_SHIFT, page);
157 if (ret < 0) {
158 kfree(candidate);
159 _leave(" = %d [prep]", ret);
160 return ret;
161 }
162 SetPageUptodate(page);
163 }
164
165try_again:
166 spin_lock(&vnode->writeback_lock);
167
168 /* see if this page is already pending a writeback under a suitable key
169 * - if so we can just join onto that one */
170 wb = (struct afs_writeback *) page_private(page);
171 if (wb) {
172 if (wb->key == key && wb->state == AFS_WBACK_PENDING)
173 goto subsume_in_current_wb;
174 goto flush_conflicting_wb;
175 }
176
177 if (index > 0) {
178 /* see if we can find an already pending writeback that we can
179 * append this page to */
180 list_for_each_entry(wb, &vnode->writebacks, link) {
181 if (wb->last == index - 1 && wb->key == key &&
182 wb->state == AFS_WBACK_PENDING)
183 goto append_to_previous_wb;
184 }
185 }
186
187 list_add_tail(&candidate->link, &vnode->writebacks);
188 candidate->key = key_get(key);
189 spin_unlock(&vnode->writeback_lock);
190 SetPagePrivate(page);
191 set_page_private(page, (unsigned long) candidate);
192 _leave(" = 0 [new]");
193 return 0;
194
195subsume_in_current_wb:
196 _debug("subsume");
197 ASSERTRANGE(wb->first, <=, index, <=, wb->last);
198 if (index == wb->first && from < wb->offset_first)
199 wb->offset_first = from;
200 if (index == wb->last && to > wb->to_last)
201 wb->to_last = to;
202 spin_unlock(&vnode->writeback_lock);
203 kfree(candidate);
204 _leave(" = 0 [sub]");
205 return 0;
206
207append_to_previous_wb:
208 _debug("append into %lx-%lx", wb->first, wb->last);
209 wb->usage++;
210 wb->last++;
211 wb->to_last = to;
212 spin_unlock(&vnode->writeback_lock);
213 SetPagePrivate(page);
214 set_page_private(page, (unsigned long) wb);
215 kfree(candidate);
216 _leave(" = 0 [app]");
217 return 0;
218
219 /* the page is currently bound to another context, so if it's dirty we
220 * need to flush it before we can use the new context */
221flush_conflicting_wb:
222 _debug("flush conflict");
223 if (wb->state == AFS_WBACK_PENDING)
224 wb->state = AFS_WBACK_CONFLICTING;
225 spin_unlock(&vnode->writeback_lock);
226 if (PageDirty(page)) {
227 ret = afs_write_back_from_locked_page(wb, page);
228 if (ret < 0) {
229 afs_put_writeback(candidate);
230 _leave(" = %d", ret);
231 return ret;
232 }
233 }
234
235 /* the page holds a ref on the writeback record */
236 afs_put_writeback(wb);
237 set_page_private(page, 0);
238 ClearPagePrivate(page);
239 goto try_again;
240}
241
242/*
243 * finalise part of a write to a page
244 */
245int afs_write_end(struct file *file, struct address_space *mapping,
246 loff_t pos, unsigned len, unsigned copied,
247 struct page *page, void *fsdata)
248{
249 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
250 loff_t i_size, maybe_i_size;
251
252 _enter("{%x:%u},{%lx}",
253 vnode->fid.vid, vnode->fid.vnode, page->index);
254
255 maybe_i_size = pos + copied;
256
257 i_size = i_size_read(&vnode->vfs_inode);
258 if (maybe_i_size > i_size) {
259 spin_lock(&vnode->writeback_lock);
260 i_size = i_size_read(&vnode->vfs_inode);
261 if (maybe_i_size > i_size)
262 i_size_write(&vnode->vfs_inode, maybe_i_size);
263 spin_unlock(&vnode->writeback_lock);
264 }
265
266 set_page_dirty(page);
267 if (PageDirty(page))
268 _debug("dirtied");
269 unlock_page(page);
270 page_cache_release(page);
271
272 return copied;
273}
274
275/*
276 * kill all the pages in the given range
277 */
278static void afs_kill_pages(struct afs_vnode *vnode, bool error,
279 pgoff_t first, pgoff_t last)
280{
281 struct pagevec pv;
282 unsigned count, loop;
283
284 _enter("{%x:%u},%lx-%lx",
285 vnode->fid.vid, vnode->fid.vnode, first, last);
286
287 pagevec_init(&pv, 0);
288
289 do {
290 _debug("kill %lx-%lx", first, last);
291
292 count = last - first + 1;
293 if (count > PAGEVEC_SIZE)
294 count = PAGEVEC_SIZE;
295 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
296 first, count, pv.pages);
297 ASSERTCMP(pv.nr, ==, count);
298
299 for (loop = 0; loop < count; loop++) {
300 ClearPageUptodate(pv.pages[loop]);
301 if (error)
302 SetPageError(pv.pages[loop]);
303 end_page_writeback(pv.pages[loop]);
304 }
305
306 __pagevec_release(&pv);
307 } while (first < last);
308
309 _leave("");
310}
311
312/*
313 * synchronously write back the locked page and any subsequent non-locked dirty
314 * pages also covered by the same writeback record
315 */
316static int afs_write_back_from_locked_page(struct afs_writeback *wb,
317 struct page *primary_page)
318{
319 struct page *pages[8], *page;
320 unsigned long count;
321 unsigned n, offset, to;
322 pgoff_t start, first, last;
323 int loop, ret;
324
325 _enter(",%lx", primary_page->index);
326
327 count = 1;
328 if (!clear_page_dirty_for_io(primary_page))
329 BUG();
330 if (test_set_page_writeback(primary_page))
331 BUG();
332
333 /* find all consecutive lockable dirty pages, stopping when we find a
334 * page that is not immediately lockable, is not dirty or is missing,
335 * or we reach the end of the range */
336 start = primary_page->index;
337 if (start >= wb->last)
338 goto no_more;
339 start++;
340 do {
341 _debug("more %lx [%lx]", start, count);
342 n = wb->last - start + 1;
343 if (n > ARRAY_SIZE(pages))
344 n = ARRAY_SIZE(pages);
345 n = find_get_pages_contig(wb->vnode->vfs_inode.i_mapping,
346 start, n, pages);
347 _debug("fgpc %u", n);
348 if (n == 0)
349 goto no_more;
350 if (pages[0]->index != start) {
351 do {
352 put_page(pages[--n]);
353 } while (n > 0);
354 goto no_more;
355 }
356
357 for (loop = 0; loop < n; loop++) {
358 page = pages[loop];
359 if (page->index > wb->last)
360 break;
361 if (!trylock_page(page))
362 break;
363 if (!PageDirty(page) ||
364 page_private(page) != (unsigned long) wb) {
365 unlock_page(page);
366 break;
367 }
368 if (!clear_page_dirty_for_io(page))
369 BUG();
370 if (test_set_page_writeback(page))
371 BUG();
372 unlock_page(page);
373 put_page(page);
374 }
375 count += loop;
376 if (loop < n) {
377 for (; loop < n; loop++)
378 put_page(pages[loop]);
379 goto no_more;
380 }
381
382 start += loop;
383 } while (start <= wb->last && count < 65536);
384
385no_more:
386 /* we now have a contiguous set of dirty pages, each with writeback set
387 * and the dirty mark cleared; the first page is locked and must remain
388 * so, all the rest are unlocked */
389 first = primary_page->index;
390 last = first + count - 1;
391
392 offset = (first == wb->first) ? wb->offset_first : 0;
393 to = (last == wb->last) ? wb->to_last : PAGE_SIZE;
394
395 _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
396
397 ret = afs_vnode_store_data(wb, first, last, offset, to);
398 if (ret < 0) {
399 switch (ret) {
400 case -EDQUOT:
401 case -ENOSPC:
402 set_bit(AS_ENOSPC,
403 &wb->vnode->vfs_inode.i_mapping->flags);
404 break;
405 case -EROFS:
406 case -EIO:
407 case -EREMOTEIO:
408 case -EFBIG:
409 case -ENOENT:
410 case -ENOMEDIUM:
411 case -ENXIO:
412 afs_kill_pages(wb->vnode, true, first, last);
413 set_bit(AS_EIO, &wb->vnode->vfs_inode.i_mapping->flags);
414 break;
415 case -EACCES:
416 case -EPERM:
417 case -ENOKEY:
418 case -EKEYEXPIRED:
419 case -EKEYREJECTED:
420 case -EKEYREVOKED:
421 afs_kill_pages(wb->vnode, false, first, last);
422 break;
423 default:
424 break;
425 }
426 } else {
427 ret = count;
428 }
429
430 _leave(" = %d", ret);
431 return ret;
432}
433
434/*
435 * write a page back to the server
436 * - the caller locked the page for us
437 */
438int afs_writepage(struct page *page, struct writeback_control *wbc)
439{
440 struct afs_writeback *wb;
441 int ret;
442
443 _enter("{%lx},", page->index);
444
445 wb = (struct afs_writeback *) page_private(page);
446 ASSERT(wb != NULL);
447
448 ret = afs_write_back_from_locked_page(wb, page);
449 unlock_page(page);
450 if (ret < 0) {
451 _leave(" = %d", ret);
452 return 0;
453 }
454
455 wbc->nr_to_write -= ret;
456
457 _leave(" = 0");
458 return 0;
459}
460
461/*
462 * write a region of pages back to the server
463 */
464static int afs_writepages_region(struct address_space *mapping,
465 struct writeback_control *wbc,
466 pgoff_t index, pgoff_t end, pgoff_t *_next)
467{
468 struct afs_writeback *wb;
469 struct page *page;
470 int ret, n;
471
472 _enter(",,%lx,%lx,", index, end);
473
474 do {
475 n = find_get_pages_tag(mapping, &index, PAGECACHE_TAG_DIRTY,
476 1, &page);
477 if (!n)
478 break;
479
480 _debug("wback %lx", page->index);
481
482 if (page->index > end) {
483 *_next = index;
484 page_cache_release(page);
485 _leave(" = 0 [%lx]", *_next);
486 return 0;
487 }
488
489 /* at this point we hold neither mapping->tree_lock nor lock on
490 * the page itself: the page may be truncated or invalidated
491 * (changing page->mapping to NULL), or even swizzled back from
492 * swapper_space to tmpfs file mapping
493 */
494 lock_page(page);
495
496 if (page->mapping != mapping) {
497 unlock_page(page);
498 page_cache_release(page);
499 continue;
500 }
501
502 if (wbc->sync_mode != WB_SYNC_NONE)
503 wait_on_page_writeback(page);
504
505 if (PageWriteback(page) || !PageDirty(page)) {
506 unlock_page(page);
507 continue;
508 }
509
510 wb = (struct afs_writeback *) page_private(page);
511 ASSERT(wb != NULL);
512
513 spin_lock(&wb->vnode->writeback_lock);
514 wb->state = AFS_WBACK_WRITING;
515 spin_unlock(&wb->vnode->writeback_lock);
516
517 ret = afs_write_back_from_locked_page(wb, page);
518 unlock_page(page);
519 page_cache_release(page);
520 if (ret < 0) {
521 _leave(" = %d", ret);
522 return ret;
523 }
524
525 wbc->nr_to_write -= ret;
526
527 cond_resched();
528 } while (index < end && wbc->nr_to_write > 0);
529
530 *_next = index;
531 _leave(" = 0 [%lx]", *_next);
532 return 0;
533}
534
535/*
536 * write some of the pending data back to the server
537 */
538int afs_writepages(struct address_space *mapping,
539 struct writeback_control *wbc)
540{
541 pgoff_t start, end, next;
542 int ret;
543
544 _enter("");
545
546 if (wbc->range_cyclic) {
547 start = mapping->writeback_index;
548 end = -1;
549 ret = afs_writepages_region(mapping, wbc, start, end, &next);
550 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
551 ret = afs_writepages_region(mapping, wbc, 0, start,
552 &next);
553 mapping->writeback_index = next;
554 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
555 end = (pgoff_t)(LLONG_MAX >> PAGE_CACHE_SHIFT);
556 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
557 if (wbc->nr_to_write > 0)
558 mapping->writeback_index = next;
559 } else {
560 start = wbc->range_start >> PAGE_CACHE_SHIFT;
561 end = wbc->range_end >> PAGE_CACHE_SHIFT;
562 ret = afs_writepages_region(mapping, wbc, start, end, &next);
563 }
564
565 _leave(" = %d", ret);
566 return ret;
567}
568
569/*
570 * completion of write to server
571 */
572void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
573{
574 struct afs_writeback *wb = call->wb;
575 struct pagevec pv;
576 unsigned count, loop;
577 pgoff_t first = call->first, last = call->last;
578 bool free_wb;
579
580 _enter("{%x:%u},{%lx-%lx}",
581 vnode->fid.vid, vnode->fid.vnode, first, last);
582
583 ASSERT(wb != NULL);
584
585 pagevec_init(&pv, 0);
586
587 do {
588 _debug("done %lx-%lx", first, last);
589
590 count = last - first + 1;
591 if (count > PAGEVEC_SIZE)
592 count = PAGEVEC_SIZE;
593 pv.nr = find_get_pages_contig(call->mapping, first, count,
594 pv.pages);
595 ASSERTCMP(pv.nr, ==, count);
596
597 spin_lock(&vnode->writeback_lock);
598 for (loop = 0; loop < count; loop++) {
599 struct page *page = pv.pages[loop];
600 end_page_writeback(page);
601 if (page_private(page) == (unsigned long) wb) {
602 set_page_private(page, 0);
603 ClearPagePrivate(page);
604 wb->usage--;
605 }
606 }
607 free_wb = false;
608 if (wb->usage == 0) {
609 afs_unlink_writeback(wb);
610 free_wb = true;
611 }
612 spin_unlock(&vnode->writeback_lock);
613 first += count;
614 if (free_wb) {
615 afs_free_writeback(wb);
616 wb = NULL;
617 }
618
619 __pagevec_release(&pv);
620 } while (first <= last);
621
622 _leave("");
623}
624
625/*
626 * write to an AFS file
627 */
628ssize_t afs_file_write(struct kiocb *iocb, const struct iovec *iov,
629 unsigned long nr_segs, loff_t pos)
630{
631 struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
632 ssize_t result;
633 size_t count = iov_length(iov, nr_segs);
634
635 _enter("{%x.%u},{%zu},%lu,",
636 vnode->fid.vid, vnode->fid.vnode, count, nr_segs);
637
638 if (IS_SWAPFILE(&vnode->vfs_inode)) {
639 printk(KERN_INFO
640 "AFS: Attempt to write to active swap file!\n");
641 return -EBUSY;
642 }
643
644 if (!count)
645 return 0;
646
647 result = generic_file_aio_write(iocb, iov, nr_segs, pos);
648 if (IS_ERR_VALUE(result)) {
649 _leave(" = %zd", result);
650 return result;
651 }
652
653 _leave(" = %zd", result);
654 return result;
655}
656
657/*
658 * flush the vnode to the fileserver
659 */
660int afs_writeback_all(struct afs_vnode *vnode)
661{
662 struct address_space *mapping = vnode->vfs_inode.i_mapping;
663 struct writeback_control wbc = {
664 .sync_mode = WB_SYNC_ALL,
665 .nr_to_write = LONG_MAX,
666 .range_cyclic = 1,
667 };
668 int ret;
669
670 _enter("");
671
672 ret = mapping->a_ops->writepages(mapping, &wbc);
673 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
674
675 _leave(" = %d", ret);
676 return ret;
677}
678
679/*
680 * flush any dirty pages for this process, and check for write errors.
681 * - the return status from this call provides a reliable indication of
682 * whether any write errors occurred for this process.
683 */
684int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
685{
686 struct dentry *dentry = file->f_path.dentry;
687 struct inode *inode = file->f_mapping->host;
688 struct afs_writeback *wb, *xwb;
689 struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
690 int ret;
691
692 _enter("{%x:%u},{n=%s},%d",
693 vnode->fid.vid, vnode->fid.vnode, dentry->d_name.name,
694 datasync);
695
696 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
697 if (ret)
698 return ret;
699 mutex_lock(&inode->i_mutex);
700
701 /* use a writeback record as a marker in the queue - when this reaches
702 * the front of the queue, all the outstanding writes are either
703 * completed or rejected */
704 wb = kzalloc(sizeof(*wb), GFP_KERNEL);
705 if (!wb) {
706 ret = -ENOMEM;
707 goto out;
708 }
709 wb->vnode = vnode;
710 wb->first = 0;
711 wb->last = -1;
712 wb->offset_first = 0;
713 wb->to_last = PAGE_SIZE;
714 wb->usage = 1;
715 wb->state = AFS_WBACK_SYNCING;
716 init_waitqueue_head(&wb->waitq);
717
718 spin_lock(&vnode->writeback_lock);
719 list_for_each_entry(xwb, &vnode->writebacks, link) {
720 if (xwb->state == AFS_WBACK_PENDING)
721 xwb->state = AFS_WBACK_CONFLICTING;
722 }
723 list_add_tail(&wb->link, &vnode->writebacks);
724 spin_unlock(&vnode->writeback_lock);
725
726 /* push all the outstanding writebacks to the server */
727 ret = afs_writeback_all(vnode);
728 if (ret < 0) {
729 afs_put_writeback(wb);
730 _leave(" = %d [wb]", ret);
731 goto out;
732 }
733
734 /* wait for the preceding writes to actually complete */
735 ret = wait_event_interruptible(wb->waitq,
736 wb->state == AFS_WBACK_COMPLETE ||
737 vnode->writebacks.next == &wb->link);
738 afs_put_writeback(wb);
739 _leave(" = %d", ret);
740out:
741 mutex_unlock(&inode->i_mutex);
742 return ret;
743}
744
745/*
746 * notification that a previously read-only page is about to become writable
747 * - if it returns an error, the caller will deliver a bus error signal
748 */
749int afs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
750{
751 struct afs_vnode *vnode = AFS_FS_I(vma->vm_file->f_mapping->host);
752
753 _enter("{{%x:%u}},{%lx}",
754 vnode->fid.vid, vnode->fid.vnode, page->index);
755
756 /* wait for the page to be written to the cache before we allow it to
757 * be modified */
758#ifdef CONFIG_AFS_FSCACHE
759 fscache_wait_on_page_write(vnode->cache, page);
760#endif
761
762 _leave(" = 0");
763 return 0;
764}