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 */
33static 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 */
54static 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 */
67static 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 */
88static 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
124no_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 */
134static 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
141const 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
149const 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