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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. wreq->netfs_priv2 will contain the last writeback key
33 * record used or NULL and we need to start from there if it's set.
34 * wreq->netfs_priv will be set to the key itself or NULL.
35 */
36static void afs_get_writeback_key(struct netfs_io_request *wreq)
37{
38 struct afs_wb_key *wbk, *old = wreq->netfs_priv2;
39 struct afs_vnode *vnode = AFS_FS_I(wreq->inode);
40
41 key_put(wreq->netfs_priv);
42 wreq->netfs_priv = NULL;
43 wreq->netfs_priv2 = NULL;
44
45 spin_lock(&vnode->wb_lock);
46 if (old)
47 wbk = list_next_entry(old, vnode_link);
48 else
49 wbk = list_first_entry(&vnode->wb_keys, struct afs_wb_key, vnode_link);
50
51 list_for_each_entry_from(wbk, &vnode->wb_keys, vnode_link) {
52 _debug("wbk %u", key_serial(wbk->key));
53 if (key_validate(wbk->key) == 0) {
54 refcount_inc(&wbk->usage);
55 wreq->netfs_priv = key_get(wbk->key);
56 wreq->netfs_priv2 = wbk;
57 _debug("USE WB KEY %u", key_serial(wbk->key));
58 break;
59 }
60 }
61
62 spin_unlock(&vnode->wb_lock);
63
64 afs_put_wb_key(old);
65}
66
67static void afs_store_data_success(struct afs_operation *op)
68{
69 struct afs_vnode *vnode = op->file[0].vnode;
70
71 op->ctime = op->file[0].scb.status.mtime_client;
72 afs_vnode_commit_status(op, &op->file[0]);
73 if (!afs_op_error(op)) {
74 afs_pages_written_back(vnode, op->store.pos, op->store.size);
75 afs_stat_v(vnode, n_stores);
76 atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
77 }
78}
79
80static const struct afs_operation_ops afs_store_data_operation = {
81 .issue_afs_rpc = afs_fs_store_data,
82 .issue_yfs_rpc = yfs_fs_store_data,
83 .success = afs_store_data_success,
84};
85
86/*
87 * Prepare a subrequest to write to the server. This sets the max_len
88 * parameter.
89 */
90void afs_prepare_write(struct netfs_io_subrequest *subreq)
91{
92 struct netfs_io_stream *stream = &subreq->rreq->io_streams[subreq->stream_nr];
93
94 //if (test_bit(NETFS_SREQ_RETRYING, &subreq->flags))
95 // subreq->max_len = 512 * 1024;
96 //else
97 stream->sreq_max_len = 256 * 1024 * 1024;
98}
99
100/*
101 * Issue a subrequest to write to the server.
102 */
103static void afs_issue_write_worker(struct work_struct *work)
104{
105 struct netfs_io_subrequest *subreq = container_of(work, struct netfs_io_subrequest, work);
106 struct netfs_io_request *wreq = subreq->rreq;
107 struct afs_operation *op;
108 struct afs_vnode *vnode = AFS_FS_I(wreq->inode);
109 unsigned long long pos = subreq->start + subreq->transferred;
110 size_t len = subreq->len - subreq->transferred;
111 int ret = -ENOKEY;
112
113 _enter("R=%x[%x],%s{%llx:%llu.%u},%llx,%zx",
114 wreq->debug_id, subreq->debug_index,
115 vnode->volume->name,
116 vnode->fid.vid,
117 vnode->fid.vnode,
118 vnode->fid.unique,
119 pos, len);
120
121#if 0 // Error injection
122 if (subreq->debug_index == 3)
123 return netfs_write_subrequest_terminated(subreq, -ENOANO, false);
124
125 if (!subreq->retry_count) {
126 set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
127 return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);
128 }
129#endif
130
131 op = afs_alloc_operation(wreq->netfs_priv, vnode->volume);
132 if (IS_ERR(op))
133 return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);
134
135 afs_op_set_vnode(op, 0, vnode);
136 op->file[0].dv_delta = 1;
137 op->file[0].modification = true;
138 op->store.pos = pos;
139 op->store.size = len;
140 op->flags |= AFS_OPERATION_UNINTR;
141 op->ops = &afs_store_data_operation;
142
143 afs_begin_vnode_operation(op);
144
145 op->store.write_iter = &subreq->io_iter;
146 op->store.i_size = umax(pos + len, vnode->netfs.remote_i_size);
147 op->mtime = inode_get_mtime(&vnode->netfs.inode);
148
149 afs_wait_for_operation(op);
150 ret = afs_put_operation(op);
151 switch (ret) {
152 case 0:
153 __set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
154 break;
155 case -EACCES:
156 case -EPERM:
157 case -ENOKEY:
158 case -EKEYEXPIRED:
159 case -EKEYREJECTED:
160 case -EKEYREVOKED:
161 /* If there are more keys we can try, use the retry algorithm
162 * to rotate the keys.
163 */
164 if (wreq->netfs_priv2)
165 set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
166 break;
167 }
168
169 netfs_write_subrequest_terminated(subreq, ret < 0 ? ret : subreq->len, false);
170}
171
172void afs_issue_write(struct netfs_io_subrequest *subreq)
173{
174 subreq->work.func = afs_issue_write_worker;
175 if (!queue_work(system_unbound_wq, &subreq->work))
176 WARN_ON_ONCE(1);
177}
178
179/*
180 * Writeback calls this when it finds a folio that needs uploading. This isn't
181 * called if writeback only has copy-to-cache to deal with.
182 */
183void afs_begin_writeback(struct netfs_io_request *wreq)
184{
185 afs_get_writeback_key(wreq);
186 wreq->io_streams[0].avail = true;
187}
188
189/*
190 * Prepare to retry the writes in request. Use this to try rotating the
191 * available writeback keys.
192 */
193void afs_retry_request(struct netfs_io_request *wreq, struct netfs_io_stream *stream)
194{
195 struct netfs_io_subrequest *subreq =
196 list_first_entry(&stream->subrequests,
197 struct netfs_io_subrequest, rreq_link);
198
199 switch (subreq->error) {
200 case -EACCES:
201 case -EPERM:
202 case -ENOKEY:
203 case -EKEYEXPIRED:
204 case -EKEYREJECTED:
205 case -EKEYREVOKED:
206 afs_get_writeback_key(wreq);
207 if (!wreq->netfs_priv)
208 stream->failed = true;
209 break;
210 }
211}
212
213/*
214 * write some of the pending data back to the server
215 */
216int afs_writepages(struct address_space *mapping, struct writeback_control *wbc)
217{
218 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
219 int ret;
220
221 /* We have to be careful as we can end up racing with setattr()
222 * truncating the pagecache since the caller doesn't take a lock here
223 * to prevent it.
224 */
225 if (wbc->sync_mode == WB_SYNC_ALL)
226 down_read(&vnode->validate_lock);
227 else if (!down_read_trylock(&vnode->validate_lock))
228 return 0;
229
230 ret = netfs_writepages(mapping, wbc);
231 up_read(&vnode->validate_lock);
232 return ret;
233}
234
235/*
236 * flush any dirty pages for this process, and check for write errors.
237 * - the return status from this call provides a reliable indication of
238 * whether any write errors occurred for this process.
239 */
240int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
241{
242 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
243 struct afs_file *af = file->private_data;
244 int ret;
245
246 _enter("{%llx:%llu},{n=%pD},%d",
247 vnode->fid.vid, vnode->fid.vnode, file,
248 datasync);
249
250 ret = afs_validate(vnode, af->key);
251 if (ret < 0)
252 return ret;
253
254 return file_write_and_wait_range(file, start, end);
255}
256
257/*
258 * notification that a previously read-only page is about to become writable
259 * - if it returns an error, the caller will deliver a bus error signal
260 */
261vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
262{
263 struct file *file = vmf->vma->vm_file;
264
265 if (afs_validate(AFS_FS_I(file_inode(file)), afs_file_key(file)) < 0)
266 return VM_FAULT_SIGBUS;
267 return netfs_page_mkwrite(vmf, NULL);
268}
269
270/*
271 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
272 */
273void afs_prune_wb_keys(struct afs_vnode *vnode)
274{
275 LIST_HEAD(graveyard);
276 struct afs_wb_key *wbk, *tmp;
277
278 /* Discard unused keys */
279 spin_lock(&vnode->wb_lock);
280
281 if (!mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
282 !mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_DIRTY)) {
283 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
284 if (refcount_read(&wbk->usage) == 1)
285 list_move(&wbk->vnode_link, &graveyard);
286 }
287 }
288
289 spin_unlock(&vnode->wb_lock);
290
291 while (!list_empty(&graveyard)) {
292 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
293 list_del(&wbk->vnode_link);
294 afs_put_wb_key(wbk);
295 }
296}
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 "internal.h"
18
19static int afs_write_back_from_locked_page(struct afs_writeback *wb,
20 struct page *page);
21
22/*
23 * mark a page as having been made dirty and thus needing writeback
24 */
25int afs_set_page_dirty(struct page *page)
26{
27 _enter("");
28 return __set_page_dirty_nobuffers(page);
29}
30
31/*
32 * unlink a writeback record because its usage has reached zero
33 * - must be called with the wb->vnode->writeback_lock held
34 */
35static void afs_unlink_writeback(struct afs_writeback *wb)
36{
37 struct afs_writeback *front;
38 struct afs_vnode *vnode = wb->vnode;
39
40 list_del_init(&wb->link);
41 if (!list_empty(&vnode->writebacks)) {
42 /* if an fsync rises to the front of the queue then wake it
43 * up */
44 front = list_entry(vnode->writebacks.next,
45 struct afs_writeback, link);
46 if (front->state == AFS_WBACK_SYNCING) {
47 _debug("wake up sync");
48 front->state = AFS_WBACK_COMPLETE;
49 wake_up(&front->waitq);
50 }
51 }
52}
53
54/*
55 * free a writeback record
56 */
57static void afs_free_writeback(struct afs_writeback *wb)
58{
59 _enter("");
60 key_put(wb->key);
61 kfree(wb);
62}
63
64/*
65 * dispose of a reference to a writeback record
66 */
67void afs_put_writeback(struct afs_writeback *wb)
68{
69 struct afs_vnode *vnode = wb->vnode;
70
71 _enter("{%d}", wb->usage);
72
73 spin_lock(&vnode->writeback_lock);
74 if (--wb->usage == 0)
75 afs_unlink_writeback(wb);
76 else
77 wb = NULL;
78 spin_unlock(&vnode->writeback_lock);
79 if (wb)
80 afs_free_writeback(wb);
81}
82
83/*
84 * partly or wholly fill a page that's under preparation for writing
85 */
86static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
87 loff_t pos, struct page *page)
88{
89 loff_t i_size;
90 int ret;
91 int len;
92
93 _enter(",,%llu", (unsigned long long)pos);
94
95 i_size = i_size_read(&vnode->vfs_inode);
96 if (pos + PAGE_CACHE_SIZE > i_size)
97 len = i_size - pos;
98 else
99 len = PAGE_CACHE_SIZE;
100
101 ret = afs_vnode_fetch_data(vnode, key, pos, len, page);
102 if (ret < 0) {
103 if (ret == -ENOENT) {
104 _debug("got NOENT from server"
105 " - marking file deleted and stale");
106 set_bit(AFS_VNODE_DELETED, &vnode->flags);
107 ret = -ESTALE;
108 }
109 }
110
111 _leave(" = %d", ret);
112 return ret;
113}
114
115/*
116 * prepare to perform part of a write to a page
117 */
118int afs_write_begin(struct file *file, struct address_space *mapping,
119 loff_t pos, unsigned len, unsigned flags,
120 struct page **pagep, void **fsdata)
121{
122 struct afs_writeback *candidate, *wb;
123 struct afs_vnode *vnode = AFS_FS_I(file->f_dentry->d_inode);
124 struct page *page;
125 struct key *key = file->private_data;
126 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
127 unsigned to = from + len;
128 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
129 int ret;
130
131 _enter("{%x:%u},{%lx},%u,%u",
132 vnode->fid.vid, vnode->fid.vnode, index, from, to);
133
134 candidate = kzalloc(sizeof(*candidate), GFP_KERNEL);
135 if (!candidate)
136 return -ENOMEM;
137 candidate->vnode = vnode;
138 candidate->first = candidate->last = index;
139 candidate->offset_first = from;
140 candidate->to_last = to;
141 INIT_LIST_HEAD(&candidate->link);
142 candidate->usage = 1;
143 candidate->state = AFS_WBACK_PENDING;
144 init_waitqueue_head(&candidate->waitq);
145
146 page = grab_cache_page_write_begin(mapping, index, flags);
147 if (!page) {
148 kfree(candidate);
149 return -ENOMEM;
150 }
151 *pagep = page;
152 /* page won't leak in error case: it eventually gets cleaned off LRU */
153
154 if (!PageUptodate(page) && len != PAGE_CACHE_SIZE) {
155 ret = afs_fill_page(vnode, key, index << PAGE_CACHE_SHIFT, page);
156 if (ret < 0) {
157 kfree(candidate);
158 _leave(" = %d [prep]", ret);
159 return ret;
160 }
161 SetPageUptodate(page);
162 }
163
164try_again:
165 spin_lock(&vnode->writeback_lock);
166
167 /* see if this page is already pending a writeback under a suitable key
168 * - if so we can just join onto that one */
169 wb = (struct afs_writeback *) page_private(page);
170 if (wb) {
171 if (wb->key == key && wb->state == AFS_WBACK_PENDING)
172 goto subsume_in_current_wb;
173 goto flush_conflicting_wb;
174 }
175
176 if (index > 0) {
177 /* see if we can find an already pending writeback that we can
178 * append this page to */
179 list_for_each_entry(wb, &vnode->writebacks, link) {
180 if (wb->last == index - 1 && wb->key == key &&
181 wb->state == AFS_WBACK_PENDING)
182 goto append_to_previous_wb;
183 }
184 }
185
186 list_add_tail(&candidate->link, &vnode->writebacks);
187 candidate->key = key_get(key);
188 spin_unlock(&vnode->writeback_lock);
189 SetPagePrivate(page);
190 set_page_private(page, (unsigned long) candidate);
191 _leave(" = 0 [new]");
192 return 0;
193
194subsume_in_current_wb:
195 _debug("subsume");
196 ASSERTRANGE(wb->first, <=, index, <=, wb->last);
197 if (index == wb->first && from < wb->offset_first)
198 wb->offset_first = from;
199 if (index == wb->last && to > wb->to_last)
200 wb->to_last = to;
201 spin_unlock(&vnode->writeback_lock);
202 kfree(candidate);
203 _leave(" = 0 [sub]");
204 return 0;
205
206append_to_previous_wb:
207 _debug("append into %lx-%lx", wb->first, wb->last);
208 wb->usage++;
209 wb->last++;
210 wb->to_last = to;
211 spin_unlock(&vnode->writeback_lock);
212 SetPagePrivate(page);
213 set_page_private(page, (unsigned long) wb);
214 kfree(candidate);
215 _leave(" = 0 [app]");
216 return 0;
217
218 /* the page is currently bound to another context, so if it's dirty we
219 * need to flush it before we can use the new context */
220flush_conflicting_wb:
221 _debug("flush conflict");
222 if (wb->state == AFS_WBACK_PENDING)
223 wb->state = AFS_WBACK_CONFLICTING;
224 spin_unlock(&vnode->writeback_lock);
225 if (PageDirty(page)) {
226 ret = afs_write_back_from_locked_page(wb, page);
227 if (ret < 0) {
228 afs_put_writeback(candidate);
229 _leave(" = %d", ret);
230 return ret;
231 }
232 }
233
234 /* the page holds a ref on the writeback record */
235 afs_put_writeback(wb);
236 set_page_private(page, 0);
237 ClearPagePrivate(page);
238 goto try_again;
239}
240
241/*
242 * finalise part of a write to a page
243 */
244int afs_write_end(struct file *file, struct address_space *mapping,
245 loff_t pos, unsigned len, unsigned copied,
246 struct page *page, void *fsdata)
247{
248 struct afs_vnode *vnode = AFS_FS_I(file->f_dentry->d_inode);
249 loff_t i_size, maybe_i_size;
250
251 _enter("{%x:%u},{%lx}",
252 vnode->fid.vid, vnode->fid.vnode, page->index);
253
254 maybe_i_size = pos + copied;
255
256 i_size = i_size_read(&vnode->vfs_inode);
257 if (maybe_i_size > i_size) {
258 spin_lock(&vnode->writeback_lock);
259 i_size = i_size_read(&vnode->vfs_inode);
260 if (maybe_i_size > i_size)
261 i_size_write(&vnode->vfs_inode, maybe_i_size);
262 spin_unlock(&vnode->writeback_lock);
263 }
264
265 set_page_dirty(page);
266 if (PageDirty(page))
267 _debug("dirtied");
268 unlock_page(page);
269 page_cache_release(page);
270
271 return copied;
272}
273
274/*
275 * kill all the pages in the given range
276 */
277static void afs_kill_pages(struct afs_vnode *vnode, bool error,
278 pgoff_t first, pgoff_t last)
279{
280 struct pagevec pv;
281 unsigned count, loop;
282
283 _enter("{%x:%u},%lx-%lx",
284 vnode->fid.vid, vnode->fid.vnode, first, last);
285
286 pagevec_init(&pv, 0);
287
288 do {
289 _debug("kill %lx-%lx", first, last);
290
291 count = last - first + 1;
292 if (count > PAGEVEC_SIZE)
293 count = PAGEVEC_SIZE;
294 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
295 first, count, pv.pages);
296 ASSERTCMP(pv.nr, ==, count);
297
298 for (loop = 0; loop < count; loop++) {
299 ClearPageUptodate(pv.pages[loop]);
300 if (error)
301 SetPageError(pv.pages[loop]);
302 end_page_writeback(pv.pages[loop]);
303 }
304
305 __pagevec_release(&pv);
306 } while (first < last);
307
308 _leave("");
309}
310
311/*
312 * synchronously write back the locked page and any subsequent non-locked dirty
313 * pages also covered by the same writeback record
314 */
315static int afs_write_back_from_locked_page(struct afs_writeback *wb,
316 struct page *primary_page)
317{
318 struct page *pages[8], *page;
319 unsigned long count;
320 unsigned n, offset, to;
321 pgoff_t start, first, last;
322 int loop, ret;
323
324 _enter(",%lx", primary_page->index);
325
326 count = 1;
327 if (!clear_page_dirty_for_io(primary_page))
328 BUG();
329 if (test_set_page_writeback(primary_page))
330 BUG();
331
332 /* find all consecutive lockable dirty pages, stopping when we find a
333 * page that is not immediately lockable, is not dirty or is missing,
334 * or we reach the end of the range */
335 start = primary_page->index;
336 if (start >= wb->last)
337 goto no_more;
338 start++;
339 do {
340 _debug("more %lx [%lx]", start, count);
341 n = wb->last - start + 1;
342 if (n > ARRAY_SIZE(pages))
343 n = ARRAY_SIZE(pages);
344 n = find_get_pages_contig(wb->vnode->vfs_inode.i_mapping,
345 start, n, pages);
346 _debug("fgpc %u", n);
347 if (n == 0)
348 goto no_more;
349 if (pages[0]->index != start) {
350 do {
351 put_page(pages[--n]);
352 } while (n > 0);
353 goto no_more;
354 }
355
356 for (loop = 0; loop < n; loop++) {
357 page = pages[loop];
358 if (page->index > wb->last)
359 break;
360 if (!trylock_page(page))
361 break;
362 if (!PageDirty(page) ||
363 page_private(page) != (unsigned long) wb) {
364 unlock_page(page);
365 break;
366 }
367 if (!clear_page_dirty_for_io(page))
368 BUG();
369 if (test_set_page_writeback(page))
370 BUG();
371 unlock_page(page);
372 put_page(page);
373 }
374 count += loop;
375 if (loop < n) {
376 for (; loop < n; loop++)
377 put_page(pages[loop]);
378 goto no_more;
379 }
380
381 start += loop;
382 } while (start <= wb->last && count < 65536);
383
384no_more:
385 /* we now have a contiguous set of dirty pages, each with writeback set
386 * and the dirty mark cleared; the first page is locked and must remain
387 * so, all the rest are unlocked */
388 first = primary_page->index;
389 last = first + count - 1;
390
391 offset = (first == wb->first) ? wb->offset_first : 0;
392 to = (last == wb->last) ? wb->to_last : PAGE_SIZE;
393
394 _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
395
396 ret = afs_vnode_store_data(wb, first, last, offset, to);
397 if (ret < 0) {
398 switch (ret) {
399 case -EDQUOT:
400 case -ENOSPC:
401 set_bit(AS_ENOSPC,
402 &wb->vnode->vfs_inode.i_mapping->flags);
403 break;
404 case -EROFS:
405 case -EIO:
406 case -EREMOTEIO:
407 case -EFBIG:
408 case -ENOENT:
409 case -ENOMEDIUM:
410 case -ENXIO:
411 afs_kill_pages(wb->vnode, true, first, last);
412 set_bit(AS_EIO, &wb->vnode->vfs_inode.i_mapping->flags);
413 break;
414 case -EACCES:
415 case -EPERM:
416 case -ENOKEY:
417 case -EKEYEXPIRED:
418 case -EKEYREJECTED:
419 case -EKEYREVOKED:
420 afs_kill_pages(wb->vnode, false, first, last);
421 break;
422 default:
423 break;
424 }
425 } else {
426 ret = count;
427 }
428
429 _leave(" = %d", ret);
430 return ret;
431}
432
433/*
434 * write a page back to the server
435 * - the caller locked the page for us
436 */
437int afs_writepage(struct page *page, struct writeback_control *wbc)
438{
439 struct afs_writeback *wb;
440 int ret;
441
442 _enter("{%lx},", page->index);
443
444 wb = (struct afs_writeback *) page_private(page);
445 ASSERT(wb != NULL);
446
447 ret = afs_write_back_from_locked_page(wb, page);
448 unlock_page(page);
449 if (ret < 0) {
450 _leave(" = %d", ret);
451 return 0;
452 }
453
454 wbc->nr_to_write -= ret;
455
456 _leave(" = 0");
457 return 0;
458}
459
460/*
461 * write a region of pages back to the server
462 */
463static int afs_writepages_region(struct address_space *mapping,
464 struct writeback_control *wbc,
465 pgoff_t index, pgoff_t end, pgoff_t *_next)
466{
467 struct afs_writeback *wb;
468 struct page *page;
469 int ret, n;
470
471 _enter(",,%lx,%lx,", index, end);
472
473 do {
474 n = find_get_pages_tag(mapping, &index, PAGECACHE_TAG_DIRTY,
475 1, &page);
476 if (!n)
477 break;
478
479 _debug("wback %lx", page->index);
480
481 if (page->index > end) {
482 *_next = index;
483 page_cache_release(page);
484 _leave(" = 0 [%lx]", *_next);
485 return 0;
486 }
487
488 /* at this point we hold neither mapping->tree_lock nor lock on
489 * the page itself: the page may be truncated or invalidated
490 * (changing page->mapping to NULL), or even swizzled back from
491 * swapper_space to tmpfs file mapping
492 */
493 lock_page(page);
494
495 if (page->mapping != mapping) {
496 unlock_page(page);
497 page_cache_release(page);
498 continue;
499 }
500
501 if (wbc->sync_mode != WB_SYNC_NONE)
502 wait_on_page_writeback(page);
503
504 if (PageWriteback(page) || !PageDirty(page)) {
505 unlock_page(page);
506 continue;
507 }
508
509 wb = (struct afs_writeback *) page_private(page);
510 ASSERT(wb != NULL);
511
512 spin_lock(&wb->vnode->writeback_lock);
513 wb->state = AFS_WBACK_WRITING;
514 spin_unlock(&wb->vnode->writeback_lock);
515
516 ret = afs_write_back_from_locked_page(wb, page);
517 unlock_page(page);
518 page_cache_release(page);
519 if (ret < 0) {
520 _leave(" = %d", ret);
521 return ret;
522 }
523
524 wbc->nr_to_write -= ret;
525
526 cond_resched();
527 } while (index < end && wbc->nr_to_write > 0);
528
529 *_next = index;
530 _leave(" = 0 [%lx]", *_next);
531 return 0;
532}
533
534/*
535 * write some of the pending data back to the server
536 */
537int afs_writepages(struct address_space *mapping,
538 struct writeback_control *wbc)
539{
540 pgoff_t start, end, next;
541 int ret;
542
543 _enter("");
544
545 if (wbc->range_cyclic) {
546 start = mapping->writeback_index;
547 end = -1;
548 ret = afs_writepages_region(mapping, wbc, start, end, &next);
549 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
550 ret = afs_writepages_region(mapping, wbc, 0, start,
551 &next);
552 mapping->writeback_index = next;
553 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
554 end = (pgoff_t)(LLONG_MAX >> PAGE_CACHE_SHIFT);
555 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
556 if (wbc->nr_to_write > 0)
557 mapping->writeback_index = next;
558 } else {
559 start = wbc->range_start >> PAGE_CACHE_SHIFT;
560 end = wbc->range_end >> PAGE_CACHE_SHIFT;
561 ret = afs_writepages_region(mapping, wbc, start, end, &next);
562 }
563
564 _leave(" = %d", ret);
565 return ret;
566}
567
568/*
569 * completion of write to server
570 */
571void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
572{
573 struct afs_writeback *wb = call->wb;
574 struct pagevec pv;
575 unsigned count, loop;
576 pgoff_t first = call->first, last = call->last;
577 bool free_wb;
578
579 _enter("{%x:%u},{%lx-%lx}",
580 vnode->fid.vid, vnode->fid.vnode, first, last);
581
582 ASSERT(wb != NULL);
583
584 pagevec_init(&pv, 0);
585
586 do {
587 _debug("done %lx-%lx", first, last);
588
589 count = last - first + 1;
590 if (count > PAGEVEC_SIZE)
591 count = PAGEVEC_SIZE;
592 pv.nr = find_get_pages_contig(call->mapping, first, count,
593 pv.pages);
594 ASSERTCMP(pv.nr, ==, count);
595
596 spin_lock(&vnode->writeback_lock);
597 for (loop = 0; loop < count; loop++) {
598 struct page *page = pv.pages[loop];
599 end_page_writeback(page);
600 if (page_private(page) == (unsigned long) wb) {
601 set_page_private(page, 0);
602 ClearPagePrivate(page);
603 wb->usage--;
604 }
605 }
606 free_wb = false;
607 if (wb->usage == 0) {
608 afs_unlink_writeback(wb);
609 free_wb = true;
610 }
611 spin_unlock(&vnode->writeback_lock);
612 first += count;
613 if (free_wb) {
614 afs_free_writeback(wb);
615 wb = NULL;
616 }
617
618 __pagevec_release(&pv);
619 } while (first <= last);
620
621 _leave("");
622}
623
624/*
625 * write to an AFS file
626 */
627ssize_t afs_file_write(struct kiocb *iocb, const struct iovec *iov,
628 unsigned long nr_segs, loff_t pos)
629{
630 struct dentry *dentry = iocb->ki_filp->f_path.dentry;
631 struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
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}