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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Unbuffered and direct write support.
3 *
4 * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells ([email protected])
6 */
7
8#include <linux/export.h>
9#include <linux/uio.h>
10#include "internal.h"
11
12/*
13 * Perform the cleanup rituals after an unbuffered write is complete.
14 */
15static void netfs_unbuffered_write_done(struct netfs_io_request *wreq)
16{
17 struct netfs_inode *ictx = netfs_inode(wreq->inode);
18
19 _enter("R=%x", wreq->debug_id);
20
21 /* Okay, declare that all I/O is complete. */
22 trace_netfs_rreq(wreq, netfs_rreq_trace_write_done);
23
24 if (wreq->transferred)
25 netfs_update_i_size(ictx, &ictx->inode, wreq->start, wreq->transferred);
26
27 if (wreq->origin == NETFS_DIO_WRITE &&
28 wreq->mapping->nrpages) {
29 /* mmap may have got underfoot and we may now have folios
30 * locally covering the region we just wrote. Attempt to
31 * discard the folios, but leave in place any modified locally.
32 * ->write_iter() is prevented from interfering by the DIO
33 * counter.
34 */
35 pgoff_t first = wreq->start >> PAGE_SHIFT;
36 pgoff_t last = (wreq->start + wreq->transferred - 1) >> PAGE_SHIFT;
37
38 invalidate_inode_pages2_range(wreq->mapping, first, last);
39 }
40
41 if (wreq->origin == NETFS_DIO_WRITE)
42 inode_dio_end(wreq->inode);
43
44 _debug("finished");
45 netfs_wake_rreq_flag(wreq, NETFS_RREQ_IN_PROGRESS, netfs_rreq_trace_wake_ip);
46 /* As we cleared NETFS_RREQ_IN_PROGRESS, we acquired its ref. */
47
48 if (wreq->iocb) {
49 size_t written = umin(wreq->transferred, wreq->len);
50
51 wreq->iocb->ki_pos += written;
52 if (wreq->iocb->ki_complete) {
53 trace_netfs_rreq(wreq, netfs_rreq_trace_ki_complete);
54 wreq->iocb->ki_complete(wreq->iocb, written ?: wreq->error);
55 }
56 wreq->iocb = VFS_PTR_POISON;
57 }
58
59 netfs_clear_subrequests(wreq);
60}
61
62/*
63 * Collect the subrequest results of unbuffered write subrequests.
64 */
65static void netfs_unbuffered_write_collect(struct netfs_io_request *wreq,
66 struct netfs_io_stream *stream,
67 struct netfs_io_subrequest *subreq)
68{
69 trace_netfs_collect_sreq(wreq, subreq);
70
71 spin_lock(&wreq->lock);
72 list_del_init(&subreq->rreq_link);
73 spin_unlock(&wreq->lock);
74
75 wreq->transferred += subreq->transferred;
76 iov_iter_advance(&wreq->buffer.iter, subreq->transferred);
77
78 stream->collected_to = subreq->start + subreq->transferred;
79 wreq->collected_to = stream->collected_to;
80 netfs_put_subrequest(subreq, netfs_sreq_trace_put_done);
81
82 trace_netfs_collect_stream(wreq, stream);
83 trace_netfs_collect_state(wreq, wreq->collected_to, 0);
84}
85
86/*
87 * Write data to the server without going through the pagecache and without
88 * writing it to the local cache. We dispatch the subrequests serially and
89 * wait for each to complete before dispatching the next, lest we leave a gap
90 * in the data written due to a failure such as ENOSPC. We could, however
91 * attempt to do preparation such as content encryption for the next subreq
92 * whilst the current is in progress.
93 */
94static int netfs_unbuffered_write(struct netfs_io_request *wreq)
95{
96 struct netfs_io_subrequest *subreq = NULL;
97 struct netfs_io_stream *stream = &wreq->io_streams[0];
98 int ret = 0;
99
100 _enter("%llx", wreq->len);
101
102 if (wreq->origin == NETFS_DIO_WRITE)
103 inode_dio_begin(wreq->inode);
104
105 stream->collected_to = wreq->start;
106
107 for (;;) {
108 bool retry = false;
109
110 if (!subreq) {
111 netfs_prepare_write(wreq, stream, wreq->start + wreq->transferred);
112 subreq = stream->construct;
113 if (!subreq) {
114 wreq->error = -ENOMEM;
115 ret = -ENOMEM;
116 break;
117 }
118 stream->construct = NULL;
119 }
120
121 /* Check if (re-)preparation failed. */
122 if (unlikely(test_bit(NETFS_SREQ_FAILED, &subreq->flags))) {
123 netfs_write_subrequest_terminated(subreq, subreq->error);
124 wreq->error = subreq->error;
125 break;
126 }
127
128 iov_iter_truncate(&subreq->io_iter, wreq->len - wreq->transferred);
129 if (!iov_iter_count(&subreq->io_iter)) {
130 pr_warn("netfs: Unexpected zero-length iterator R=%08x\n",
131 wreq->debug_id);
132 __set_bit(NETFS_SREQ_FAILED, &subreq->flags);
133 netfs_write_subrequest_terminated(subreq, -EIO);
134 wreq->error = -EIO;
135 break;
136 }
137
138 subreq->len = netfs_limit_iter(&subreq->io_iter, 0,
139 stream->sreq_max_len,
140 stream->sreq_max_segs);
141 iov_iter_truncate(&subreq->io_iter, subreq->len);
142 stream->submit_extendable_to = subreq->len;
143
144 trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
145 stream->issue_write(subreq);
146
147 /* Async, need to wait. */
148 netfs_wait_for_in_progress_stream(wreq, stream);
149
150 if (test_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) {
151 retry = true;
152 } else if (test_bit(NETFS_SREQ_FAILED, &subreq->flags)) {
153 wreq->error = subreq->error;
154 netfs_see_subrequest(subreq, netfs_sreq_trace_see_failed);
155 subreq = NULL;
156 break;
157 }
158
159 if (!retry) {
160 netfs_unbuffered_write_collect(wreq, stream, subreq);
161 subreq = NULL;
162 if (wreq->transferred >= wreq->len)
163 break;
164 if (!wreq->iocb && signal_pending(current)) {
165 ret = wreq->transferred ? -EINTR : -ERESTARTSYS;
166 trace_netfs_rreq(wreq, netfs_rreq_trace_intr);
167 break;
168 }
169 continue;
170 }
171
172 /* We need to retry the last subrequest, so first reset the
173 * iterator, taking into account what, if anything, we managed
174 * to transfer.
175 */
176 subreq->error = -EAGAIN;
177 trace_netfs_sreq(subreq, netfs_sreq_trace_retry);
178 if (subreq->transferred > 0) {
179 iov_iter_advance(&wreq->buffer.iter, subreq->transferred);
180 wreq->transferred += subreq->transferred;
181 }
182
183 if (stream->source == NETFS_UPLOAD_TO_SERVER &&
184 wreq->netfs_ops->retry_request)
185 wreq->netfs_ops->retry_request(wreq, stream);
186
187 __clear_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
188 __clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
189 __clear_bit(NETFS_SREQ_BOUNDARY, &subreq->flags);
190 __clear_bit(NETFS_SREQ_FAILED, &subreq->flags);
191 subreq->io_iter = wreq->buffer.iter;
192 subreq->start = wreq->start + wreq->transferred;
193 subreq->len = wreq->len - wreq->transferred;
194 subreq->transferred = 0;
195 subreq->retry_count += 1;
196 stream->sreq_max_len = UINT_MAX;
197 stream->sreq_max_segs = INT_MAX;
198
199 netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);
200
201 if (stream->prepare_write)
202 stream->prepare_write(subreq);
203 __set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
204 netfs_stat(&netfs_n_wh_retry_write_subreq);
205 }
206
207 netfs_unbuffered_write_done(wreq);
208 _leave(" = %d", ret);
209 return ret;
210}
211
212static void netfs_unbuffered_write_async(struct work_struct *work)
213{
214 struct netfs_io_request *wreq = container_of(work, struct netfs_io_request, work);
215
216 netfs_unbuffered_write(wreq);
217 netfs_put_request(wreq, netfs_rreq_trace_put_complete);
218}
219
220/*
221 * Perform an unbuffered write where we may have to do an RMW operation on an
222 * encrypted file. This can also be used for direct I/O writes.
223 */
224ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,
225 struct netfs_group *netfs_group)
226{
227 struct netfs_io_request *wreq;
228 ssize_t ret, n;
229 uoff_t start = iocb->ki_pos;
230 uoff_t end = start + iov_iter_count(iter);
231 size_t len = iov_iter_count(iter);
232 bool async = !is_sync_kiocb(iocb);
233
234 _enter("");
235
236 /* We're going to need a bounce buffer if what we transmit is going to
237 * be different in some way to the source buffer, e.g. because it gets
238 * encrypted/compressed or because it needs expanding to a block size.
239 */
240 // TODO
241
242 _debug("uw %llx-%llx", start, end);
243
244 wreq = netfs_create_write_req(iocb->ki_filp->f_mapping, iocb->ki_filp, start,
245 iocb->ki_flags & IOCB_DIRECT ?
246 NETFS_DIO_WRITE : NETFS_UNBUFFERED_WRITE);
247 if (IS_ERR(wreq))
248 return PTR_ERR(wreq);
249
250 wreq->io_streams[0].avail = true;
251 trace_netfs_write(wreq, (iocb->ki_flags & IOCB_DIRECT ?
252 netfs_write_trace_dio_write :
253 netfs_write_trace_unbuffered_write));
254
255 {
256 /* If this is an async op and we're not using a bounce buffer,
257 * we have to save the source buffer as the iterator is only
258 * good until we return. In such a case, extract an iterator
259 * to represent as much of the the output buffer as we can
260 * manage. Note that the extraction might not be able to
261 * allocate a sufficiently large bvec array and may shorten the
262 * request.
263 */
264 if (user_backed_iter(iter)) {
265 n = netfs_extract_user_iter(iter, len, &wreq->buffer.iter, 0);
266 if (n < 0) {
267 ret = n;
268 goto error_put;
269 }
270 wreq->direct_bv = (struct bio_vec *)wreq->buffer.iter.bvec;
271 wreq->direct_bv_count = n;
272 wreq->direct_bv_unpin = iov_iter_extract_will_pin(iter);
273 } else {
274 /* If this is a kernel-generated async DIO request,
275 * assume that any resources the iterator points to
276 * (eg. a bio_vec array) will persist till the end of
277 * the op.
278 */
279 wreq->buffer.iter = *iter;
280 }
281
282 wreq->len = iov_iter_count(&wreq->buffer.iter);
283 }
284
285 __set_bit(NETFS_RREQ_USE_IO_ITER, &wreq->flags);
286
287 /* Copy the data into the bounce buffer and encrypt it. */
288 // TODO
289
290 /* Dispatch the write. */
291 __set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags);
292
293 if (async) {
294 INIT_WORK(&wreq->work, netfs_unbuffered_write_async);
295 wreq->iocb = iocb;
296 queue_work(system_dfl_wq, &wreq->work);
297 ret = -EIOCBQUEUED;
298 } else {
299 ret = netfs_unbuffered_write(wreq);
300 if (wreq->transferred) {
301 iocb->ki_pos += wreq->transferred;
302 ret = wreq->transferred;
303 } else if (wreq->error) {
304 ret = wreq->error;
305 }
306
307 netfs_put_request(wreq, netfs_rreq_trace_put_complete);
308 }
309
310 netfs_put_request(wreq, netfs_rreq_trace_put_return);
311 return ret;
312
313error_put:
314 netfs_put_failed_request(wreq);
315 return ret;
316}
317EXPORT_SYMBOL(netfs_unbuffered_write_iter_locked);
318
319/**
320 * netfs_unbuffered_write_iter - Unbuffered write to a file
321 * @iocb: IO state structure
322 * @from: iov_iter with data to write
323 *
324 * Do an unbuffered write to a file, writing the data directly to the server
325 * and not lodging the data in the pagecache.
326 *
327 * Return:
328 * * Negative error code if no data has been written at all of
329 * vfs_fsync_range() failed for a synchronous write
330 * * Number of bytes written, even for truncated writes
331 */
332ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from)
333{
334 struct file *file = iocb->ki_filp;
335 struct address_space *mapping = file->f_mapping;
336 struct inode *inode = mapping->host;
337 struct netfs_inode *ictx = netfs_inode(inode);
338 ssize_t ret;
339 uoff_t pos = iocb->ki_pos;
340 uoff_t end = pos + iov_iter_count(from) - 1;
341
342 _enter("%llx,%zx,%llx", pos, iov_iter_count(from), i_size_read(inode));
343
344 if (!iov_iter_count(from))
345 return 0;
346
347 trace_netfs_write_iter(iocb, from);
348 netfs_stat(&netfs_n_wh_dio_write);
349
350 ret = netfs_start_io_direct(inode);
351 if (ret < 0)
352 return ret;
353 ret = generic_write_checks(iocb, from);
354 if (ret <= 0)
355 goto out;
356 ret = file_remove_privs(file);
357 if (ret < 0)
358 goto out;
359 ret = file_update_time(file);
360 if (ret < 0)
361 goto out;
362
363 if (iocb->ki_pos > i_size_read(inode)) {
364 ret = netfs_clear_stale_pre_isize(inode, i_size_read(inode),
365 iocb->ki_pos,
366 iocb->ki_flags & IOCB_NOWAIT);
367 if (ret < 0)
368 goto out;
369 }
370
371 if (iocb->ki_flags & IOCB_NOWAIT) {
372 /* We could block if there are any pages in the range. */
373 ret = -EAGAIN;
374 if (filemap_range_has_page(mapping, pos, end))
375 if (filemap_invalidate_inode(inode, true, pos, end))
376 goto out;
377 } else {
378 ret = filemap_write_and_wait_range(mapping, pos, end);
379 if (ret < 0)
380 goto out;
381 }
382
383 /*
384 * After a write we want buffered reads to be sure to go to disk to get
385 * the new data. We invalidate clean cached page from the region we're
386 * about to write. We do this *before* the write so that we can return
387 * without clobbering -EIOCBQUEUED from ->direct_IO().
388 */
389 ret = filemap_invalidate_inode(inode, true, pos, end);
390 if (ret < 0)
391 goto out;
392 end = iocb->ki_pos + iov_iter_count(from);
393 spin_lock(&inode->i_lock);
394 if (end > ictx->_zero_point)
395 netfs_write_zero_point(inode, end);
396 spin_unlock(&inode->i_lock);
397
398 fscache_invalidate(netfs_i_cookie(ictx), NULL, i_size_read(inode),
399 FSCACHE_INVAL_DIO_WRITE);
400 ret = netfs_unbuffered_write_iter_locked(iocb, from, NULL);
401out:
402 netfs_end_io_direct(inode);
403 return ret;
404}
405EXPORT_SYMBOL(netfs_unbuffered_write_iter);