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 */
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=%lx\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 */
54 static void v9fs_issue_write(struct netfs_io_subrequest *subreq)
55 {
56 struct p9_fid *fid = subreq->rreq->netfs_priv;
57 int err, len;
58
59 len = p9_client_write(fid, subreq->start, &subreq->io_iter, &err);
60 netfs_write_subrequest_terminated(subreq, len ?: err, false);
61 }
62
63 /**
64 * v9fs_issue_read - Issue a read from 9P
65 * @subreq: The read to make
66 */
67 static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
68 {
69 struct netfs_io_request *rreq = subreq->rreq;
70 struct p9_fid *fid = rreq->netfs_priv;
71 int total, err;
72
73 total = p9_client_read(fid, subreq->start + subreq->transferred,
74 &subreq->io_iter, &err);
75
76 /* if we just extended the file size, any portion not in
77 * cache won't be on server and is zeroes */
78 __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
79
80 netfs_subreq_terminated(subreq, err ?: total, false);
81 }
82
83 /**
84 * v9fs_init_request - Initialise a request
85 * @rreq: The read request
86 * @file: The file being read from
87 */
88 static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
89 {
90 struct p9_fid *fid;
91 bool writing = (rreq->origin == NETFS_READ_FOR_WRITE ||
92 rreq->origin == NETFS_WRITETHROUGH ||
93 rreq->origin == NETFS_UNBUFFERED_WRITE ||
94 rreq->origin == NETFS_DIO_WRITE);
95
96 if (rreq->origin == NETFS_WRITEBACK)
97 return 0; /* We don't get the write handle until we find we
98 * have actually dirty data and not just
99 * copy-to-cache data.
100 */
101
102 if (file) {
103 fid = file->private_data;
104 if (!fid)
105 goto no_fid;
106 p9_fid_get(fid);
107 } else {
108 fid = v9fs_fid_find_inode(rreq->inode, writing, INVALID_UID, true);
109 if (!fid)
110 goto no_fid;
111 }
112
113 rreq->wsize = fid->clnt->msize - P9_IOHDRSZ;
114 if (fid->iounit)
115 rreq->wsize = min(rreq->wsize, fid->iounit);
116
117 /* we might need to read from a fid that was opened write-only
118 * for read-modify-write of page cache, use the writeback fid
119 * for that */
120 WARN_ON(rreq->origin == NETFS_READ_FOR_WRITE && !(fid->mode & P9_ORDWR));
121 rreq->netfs_priv = fid;
122 return 0;
123
124 no_fid:
125 WARN_ONCE(1, "folio expected an open fid inode->i_ino=%lx\n",
126 rreq->inode->i_ino);
127 return -EINVAL;
128 }
129
130 /**
131 * v9fs_free_request - Cleanup request initialized by v9fs_init_rreq
132 * @rreq: The I/O request to clean up
133 */
134 static void v9fs_free_request(struct netfs_io_request *rreq)
135 {
136 struct p9_fid *fid = rreq->netfs_priv;
137
138 p9_fid_put(fid);
139 }
140
141 const struct netfs_request_ops v9fs_req_ops = {
142 .init_request = v9fs_init_request,
143 .free_request = v9fs_free_request,
144 .issue_read = v9fs_issue_read,
145 .begin_writeback = v9fs_begin_writeback,
146 .issue_write = v9fs_issue_write,
147 };
148
149 const struct address_space_operations v9fs_addr_operations = {
150 .read_folio = netfs_read_folio,
151 .readahead = netfs_readahead,
152 .dirty_folio = netfs_dirty_folio,
153 .release_folio = netfs_release_folio,
154 .invalidate_folio = netfs_invalidate_folio,
155 .direct_IO = noop_direct_IO,
156 .writepages = netfs_writepages,
157 };
158
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