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=%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 */ 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 if (len > 0) 61 __set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags); 62 netfs_write_subrequest_terminated(subreq, len ?: err); 63 } 64 65 /** 66 * v9fs_issue_read - Issue a read from 9P 67 * @subreq: The read to make 68 */ 69 static void v9fs_issue_read(struct netfs_io_subrequest *subreq) 70 { 71 struct netfs_io_request *rreq = subreq->rreq; 72 struct p9_fid *fid = rreq->netfs_priv; 73 char *target; 74 unsigned long long pos = subreq->start + subreq->transferred; 75 int total = 0, err, len, n; 76 77 if (S_ISLNK(rreq->inode->i_mode)) { 78 /* p9_client_readlink() must not be called for legacy protocols 79 * 9p2000 or 9p2000.u. 80 */ 81 BUG_ON(!p9_is_proto_dotl(fid->clnt)); 82 if (WARN_ON_ONCE(pos)) { 83 /* reading a link at a non null offset should 84 * not happen 85 */ 86 err = -EIO; 87 goto fill_subreq; 88 } 89 err = p9_client_readlink(fid, &target); 90 if (err != 0) 91 goto fill_subreq; 92 len = strlen(target); 93 n = copy_to_iter(target, len, &subreq->io_iter); 94 kfree(target); 95 total = n; 96 } else { 97 total = p9_client_read(fid, pos, &subreq->io_iter, &err); 98 } 99 100 fill_subreq: 101 /* if we just extended the file size, any portion not in 102 * cache won't be on server and is zeroes */ 103 if (subreq->rreq->origin != NETFS_UNBUFFERED_READ && 104 subreq->rreq->origin != NETFS_DIO_READ) 105 __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags); 106 if (pos + total >= i_size_read(rreq->inode)) 107 __set_bit(NETFS_SREQ_HIT_EOF, &subreq->flags); 108 if (!err && total) { 109 subreq->transferred += total; 110 __set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags); 111 } 112 113 subreq->error = err; 114 netfs_read_subreq_terminated(subreq); 115 } 116 117 /** 118 * v9fs_init_request - Initialise a request 119 * @rreq: The read request 120 * @file: The file being read from 121 */ 122 static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file) 123 { 124 struct p9_fid *fid; 125 struct dentry *dentry; 126 bool writing = (rreq->origin == NETFS_READ_FOR_WRITE || 127 rreq->origin == NETFS_WRITETHROUGH || 128 rreq->origin == NETFS_UNBUFFERED_WRITE || 129 rreq->origin == NETFS_DIO_WRITE); 130 131 if (rreq->origin == NETFS_WRITEBACK) 132 return 0; /* We don't get the write handle until we find we 133 * have actually dirty data and not just 134 * copy-to-cache data. 135 */ 136 137 if (file) { 138 fid = file->private_data; 139 if (!fid) 140 goto no_fid; 141 p9_fid_get(fid); 142 } else if (S_ISLNK(rreq->inode->i_mode)) { 143 dentry = d_find_any_alias(rreq->inode); 144 if (!dentry) 145 goto no_fid; 146 fid = v9fs_fid_lookup(dentry); 147 dput(dentry); 148 if (IS_ERR(fid)) 149 goto no_fid; 150 } else { 151 fid = v9fs_fid_find_inode(rreq->inode, writing, INVALID_UID, true); 152 if (!fid) 153 goto no_fid; 154 } 155 156 rreq->wsize = fid->clnt->msize - P9_IOHDRSZ; 157 if (fid->iounit) 158 rreq->wsize = min(rreq->wsize, fid->iounit); 159 160 /* we might need to read from a fid that was opened write-only 161 * for read-modify-write of page cache, use the writeback fid 162 * for that */ 163 WARN_ON(rreq->origin == NETFS_READ_FOR_WRITE && !(fid->mode & P9_ORDWR)); 164 rreq->netfs_priv = fid; 165 return 0; 166 167 no_fid: 168 WARN_ONCE(1, "folio expected an open fid inode->i_ino=%llx\n", 169 rreq->inode->i_ino); 170 return -EINVAL; 171 } 172 173 /** 174 * v9fs_free_request - Cleanup request initialized by v9fs_init_rreq 175 * @rreq: The I/O request to clean up 176 */ 177 static void v9fs_free_request(struct netfs_io_request *rreq) 178 { 179 struct p9_fid *fid = rreq->netfs_priv; 180 181 p9_fid_put(fid); 182 } 183 184 const struct netfs_request_ops v9fs_req_ops = { 185 .init_request = v9fs_init_request, 186 .free_request = v9fs_free_request, 187 .issue_read = v9fs_issue_read, 188 .begin_writeback = v9fs_begin_writeback, 189 .issue_write = v9fs_issue_write, 190 }; 191 192 const struct address_space_operations v9fs_addr_operations = { 193 .read_folio = netfs_read_folio, 194 .readahead = netfs_readahead, 195 .dirty_folio = netfs_dirty_folio, 196 .release_folio = netfs_release_folio, 197 .invalidate_folio = netfs_invalidate_folio, 198 .direct_IO = noop_direct_IO, 199 .writepages = netfs_writepages, 200 .migrate_folio = filemap_migrate_folio, 201 }; 202