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 (dhowells@redhat.com)
6 */
7
8 #include <linux/export.h>
9 #include <linux/uio.h>
10 #include "internal.h"
11
12 /*
13 * Perform an unbuffered write where we may have to do an RMW operation on an
14 * encrypted file. This can also be used for direct I/O writes.
15 */
netfs_unbuffered_write_iter_locked(struct kiocb * iocb,struct iov_iter * iter,struct netfs_group * netfs_group)16 ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,
17 struct netfs_group *netfs_group)
18 {
19 struct netfs_io_request *wreq;
20 unsigned long long start = iocb->ki_pos;
21 unsigned long long end = start + iov_iter_count(iter);
22 ssize_t ret, n;
23 size_t len = iov_iter_count(iter);
24 bool async = !is_sync_kiocb(iocb);
25
26 _enter("");
27
28 /* We're going to need a bounce buffer if what we transmit is going to
29 * be different in some way to the source buffer, e.g. because it gets
30 * encrypted/compressed or because it needs expanding to a block size.
31 */
32 // TODO
33
34 _debug("uw %llx-%llx", start, end);
35
36 wreq = netfs_create_write_req(iocb->ki_filp->f_mapping, iocb->ki_filp, start,
37 iocb->ki_flags & IOCB_DIRECT ?
38 NETFS_DIO_WRITE : NETFS_UNBUFFERED_WRITE);
39 if (IS_ERR(wreq))
40 return PTR_ERR(wreq);
41
42 wreq->io_streams[0].avail = true;
43 trace_netfs_write(wreq, (iocb->ki_flags & IOCB_DIRECT ?
44 netfs_write_trace_dio_write :
45 netfs_write_trace_unbuffered_write));
46
47 {
48 /* If this is an async op and we're not using a bounce buffer,
49 * we have to save the source buffer as the iterator is only
50 * good until we return. In such a case, extract an iterator
51 * to represent as much of the the output buffer as we can
52 * manage. Note that the extraction might not be able to
53 * allocate a sufficiently large bvec array and may shorten the
54 * request.
55 */
56 if (user_backed_iter(iter)) {
57 n = netfs_extract_user_iter(iter, len, &wreq->buffer.iter, 0);
58 if (n < 0) {
59 ret = n;
60 goto out;
61 }
62 wreq->direct_bv = (struct bio_vec *)wreq->buffer.iter.bvec;
63 wreq->direct_bv_count = n;
64 wreq->direct_bv_unpin = iov_iter_extract_will_pin(iter);
65 } else {
66 /* If this is a kernel-generated async DIO request,
67 * assume that any resources the iterator points to
68 * (eg. a bio_vec array) will persist till the end of
69 * the op.
70 */
71 wreq->buffer.iter = *iter;
72 }
73 }
74
75 __set_bit(NETFS_RREQ_USE_IO_ITER, &wreq->flags);
76 if (async)
77 __set_bit(NETFS_RREQ_OFFLOAD_COLLECTION, &wreq->flags);
78
79 /* Copy the data into the bounce buffer and encrypt it. */
80 // TODO
81
82 /* Dispatch the write. */
83 __set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags);
84 if (async)
85 wreq->iocb = iocb;
86 wreq->len = iov_iter_count(&wreq->buffer.iter);
87 ret = netfs_unbuffered_write(wreq, is_sync_kiocb(iocb), wreq->len);
88 if (ret < 0) {
89 _debug("begin = %zd", ret);
90 goto out;
91 }
92
93 if (!async) {
94 ret = netfs_wait_for_write(wreq);
95 if (ret > 0)
96 iocb->ki_pos += ret;
97 } else {
98 ret = -EIOCBQUEUED;
99 }
100
101 out:
102 netfs_put_request(wreq, netfs_rreq_trace_put_return);
103 return ret;
104 }
105 EXPORT_SYMBOL(netfs_unbuffered_write_iter_locked);
106
107 /**
108 * netfs_unbuffered_write_iter - Unbuffered write to a file
109 * @iocb: IO state structure
110 * @from: iov_iter with data to write
111 *
112 * Do an unbuffered write to a file, writing the data directly to the server
113 * and not lodging the data in the pagecache.
114 *
115 * Return:
116 * * Negative error code if no data has been written at all of
117 * vfs_fsync_range() failed for a synchronous write
118 * * Number of bytes written, even for truncated writes
119 */
netfs_unbuffered_write_iter(struct kiocb * iocb,struct iov_iter * from)120 ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from)
121 {
122 struct file *file = iocb->ki_filp;
123 struct address_space *mapping = file->f_mapping;
124 struct inode *inode = mapping->host;
125 struct netfs_inode *ictx = netfs_inode(inode);
126 ssize_t ret;
127 loff_t pos = iocb->ki_pos;
128 unsigned long long end = pos + iov_iter_count(from) - 1;
129
130 _enter("%llx,%zx,%llx", pos, iov_iter_count(from), i_size_read(inode));
131
132 if (!iov_iter_count(from))
133 return 0;
134
135 trace_netfs_write_iter(iocb, from);
136 netfs_stat(&netfs_n_wh_dio_write);
137
138 ret = netfs_start_io_direct(inode);
139 if (ret < 0)
140 return ret;
141 ret = generic_write_checks(iocb, from);
142 if (ret <= 0)
143 goto out;
144 ret = file_remove_privs(file);
145 if (ret < 0)
146 goto out;
147 ret = file_update_time(file);
148 if (ret < 0)
149 goto out;
150 if (iocb->ki_flags & IOCB_NOWAIT) {
151 /* We could block if there are any pages in the range. */
152 ret = -EAGAIN;
153 if (filemap_range_has_page(mapping, pos, end))
154 if (filemap_invalidate_inode(inode, true, pos, end))
155 goto out;
156 } else {
157 ret = filemap_write_and_wait_range(mapping, pos, end);
158 if (ret < 0)
159 goto out;
160 }
161
162 /*
163 * After a write we want buffered reads to be sure to go to disk to get
164 * the new data. We invalidate clean cached page from the region we're
165 * about to write. We do this *before* the write so that we can return
166 * without clobbering -EIOCBQUEUED from ->direct_IO().
167 */
168 ret = filemap_invalidate_inode(inode, true, pos, end);
169 if (ret < 0)
170 goto out;
171 end = iocb->ki_pos + iov_iter_count(from);
172 if (end > ictx->zero_point)
173 ictx->zero_point = end;
174
175 fscache_invalidate(netfs_i_cookie(ictx), NULL, i_size_read(inode),
176 FSCACHE_INVAL_DIO_WRITE);
177 ret = netfs_unbuffered_write_iter_locked(iocb, from, NULL);
178 out:
179 netfs_end_io_direct(inode);
180 return ret;
181 }
182 EXPORT_SYMBOL(netfs_unbuffered_write_iter);
183