1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * This file contians vfs address (mmap) ops for 9P2000.
4 *
5 * Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
6 * Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
7 */
8
9 #include <linux/module.h>
10 #include <linux/errno.h>
11 #include <linux/fs.h>
12 #include <linux/file.h>
13 #include <linux/stat.h>
14 #include <linux/string.h>
15 #include <linux/pagemap.h>
16 #include <linux/sched.h>
17 #include <linux/swap.h>
18 #include <linux/uio.h>
19 #include <linux/netfs.h>
20 #include <net/9p/9p.h>
21 #include <net/9p/client.h>
22 #include <trace/events/netfs.h>
23
24 #include "v9fs.h"
25 #include "v9fs_vfs.h"
26 #include "cache.h"
27 #include "fid.h"
28
29 /*
30 * Writeback calls this when it finds a folio that needs uploading. This isn't
31 * called if writeback only has copy-to-cache to deal with.
32 */
v9fs_begin_writeback(struct netfs_io_request * wreq)33 static void v9fs_begin_writeback(struct netfs_io_request *wreq)
34 {
35 struct p9_fid *fid;
36
37 fid = v9fs_fid_find_inode(wreq->inode, true, INVALID_UID, true);
38 if (!fid) {
39 WARN_ONCE(1, "folio expected an open fid inode->i_ino=%llx\n",
40 wreq->inode->i_ino);
41 return;
42 }
43
44 wreq->wsize = fid->clnt->msize - P9_IOHDRSZ;
45 if (fid->iounit)
46 wreq->wsize = min(wreq->wsize, fid->iounit);
47 wreq->netfs_priv = fid;
48 wreq->io_streams[0].avail = true;
49 }
50
51 /*
52 * Issue a subrequest to write to the server.
53 */
v9fs_issue_write(struct netfs_io_subrequest * subreq)54 static void v9fs_issue_write(struct netfs_io_subrequest *subreq)
55 {
56 struct p9_fid *fid = subreq->rreq->netfs_priv;
57 struct inode *inode = subreq->rreq->inode;
58 struct netfs_inode *ictx = netfs_inode(inode);
59 int err, len;
60
61 len = p9_client_write(fid, subreq->start, &subreq->io_iter, &err);
62 if (len > 0) {
63 uoff_t end = subreq->start + len, i_size, remote, zp;
64 bool set = false;
65
66 spin_lock(&inode->i_lock);
67
68 /* We can read the sizes directly as we hold i_lock. */
69 i_size = inode->i_size;
70 remote = ictx->_remote_i_size;
71 zp = ictx->_zero_point;
72
73 if (end > i_size) {
74 i_size = end;
75 set = true;
76 }
77 if (end > remote) {
78 remote = end;
79 set = true;
80 }
81
82 if (set)
83 netfs_write_sizes(inode, i_size, remote, zp);
84 spin_unlock(&inode->i_lock);
85
86 __set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
87 }
88 netfs_write_subrequest_terminated(subreq, len ?: err);
89 }
90
91 /**
92 * v9fs_issue_read - Issue a read from 9P
93 * @subreq: The read to make
94 */
v9fs_issue_read(struct netfs_io_subrequest * subreq)95 static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
96 {
97 struct netfs_io_request *rreq = subreq->rreq;
98 struct p9_fid *fid = rreq->netfs_priv;
99 char *target;
100 unsigned long long pos = subreq->start + subreq->transferred;
101 int total = 0, err, len, n;
102
103 if (S_ISLNK(rreq->inode->i_mode)) {
104 /* p9_client_readlink() must not be called for legacy protocols
105 * 9p2000 or 9p2000.u.
106 */
107 BUG_ON(!p9_is_proto_dotl(fid->clnt));
108 if (WARN_ON_ONCE(pos)) {
109 /* reading a link at a non null offset should
110 * not happen
111 */
112 err = -EIO;
113 goto fill_subreq;
114 }
115 err = p9_client_readlink(fid, &target);
116 if (err != 0)
117 goto fill_subreq;
118 len = strlen(target);
119 n = copy_to_iter(target, len, &subreq->io_iter);
120 kfree(target);
121 total = n;
122 } else {
123 total = p9_client_read(fid, pos, &subreq->io_iter, &err);
124 }
125
126 fill_subreq:
127 /* if we just extended the file size, any portion not in
128 * cache won't be on server and is zeroes */
129 if (subreq->rreq->origin != NETFS_UNBUFFERED_READ &&
130 subreq->rreq->origin != NETFS_DIO_READ)
131 __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
132 if (pos + total >= i_size_read(rreq->inode))
133 __set_bit(NETFS_SREQ_HIT_EOF, &subreq->flags);
134 if (!err && total) {
135 subreq->transferred += total;
136 __set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
137 }
138
139 subreq->error = err;
140 netfs_read_subreq_terminated(subreq);
141 }
142
143 /**
144 * v9fs_init_request - Initialise a request
145 * @rreq: The read request
146 * @file: The file being read from
147 */
v9fs_init_request(struct netfs_io_request * rreq,struct file * file)148 static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
149 {
150 struct p9_fid *fid;
151 struct dentry *dentry;
152 bool writing = (rreq->origin == NETFS_READ_FOR_WRITE ||
153 rreq->origin == NETFS_WRITETHROUGH ||
154 rreq->origin == NETFS_UNBUFFERED_WRITE ||
155 rreq->origin == NETFS_DIO_WRITE);
156
157 if (rreq->origin == NETFS_WRITEBACK)
158 return 0; /* We don't get the write handle until we find we
159 * have actually dirty data and not just
160 * copy-to-cache data.
161 */
162
163 if (file) {
164 fid = file->private_data;
165 if (!fid)
166 goto no_fid;
167 p9_fid_get(fid);
168 } else if (S_ISLNK(rreq->inode->i_mode)) {
169 dentry = d_find_any_alias(rreq->inode);
170 if (!dentry)
171 goto no_fid;
172 fid = v9fs_fid_lookup(dentry);
173 dput(dentry);
174 if (IS_ERR(fid))
175 goto no_fid;
176 } else {
177 fid = v9fs_fid_find_inode(rreq->inode, writing, INVALID_UID, true);
178 if (!fid)
179 goto no_fid;
180 }
181
182 rreq->wsize = fid->clnt->msize - P9_IOHDRSZ;
183 if (fid->iounit)
184 rreq->wsize = min(rreq->wsize, fid->iounit);
185
186 /* we might need to read from a fid that was opened write-only
187 * for read-modify-write of page cache, use the writeback fid
188 * for that */
189 WARN_ON(rreq->origin == NETFS_READ_FOR_WRITE && !(fid->mode & P9_ORDWR));
190 rreq->netfs_priv = fid;
191 return 0;
192
193 no_fid:
194 WARN_ONCE(1, "folio expected an open fid inode->i_ino=%llx\n",
195 rreq->inode->i_ino);
196 return -EINVAL;
197 }
198
199 /**
200 * v9fs_free_request - Cleanup request initialized by v9fs_init_rreq
201 * @rreq: The I/O request to clean up
202 */
v9fs_free_request(struct netfs_io_request * rreq)203 static void v9fs_free_request(struct netfs_io_request *rreq)
204 {
205 struct p9_fid *fid = rreq->netfs_priv;
206
207 p9_fid_put(fid);
208 }
209
210 const struct netfs_request_ops v9fs_req_ops = {
211 .init_request = v9fs_init_request,
212 .free_request = v9fs_free_request,
213 .issue_read = v9fs_issue_read,
214 .begin_writeback = v9fs_begin_writeback,
215 .issue_write = v9fs_issue_write,
216 };
217
218 const struct address_space_operations v9fs_addr_operations = {
219 .read_folio = netfs_read_folio,
220 .readahead = netfs_readahead,
221 .dirty_folio = netfs_dirty_folio,
222 .release_folio = netfs_release_folio,
223 .invalidate_folio = netfs_invalidate_folio,
224 .direct_IO = noop_direct_IO,
225 .writepages = netfs_writepages,
226 .migrate_folio = filemap_migrate_folio,
227 };
228