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 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 */ 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 */ 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_UNBUFFERED_WRITE || 154 rreq->origin == NETFS_DIO_WRITE); 155 156 if (rreq->origin == NETFS_WRITEBACK) 157 return 0; /* We don't get the write handle until we find we 158 * have actually dirty data and not just 159 * copy-to-cache data. 160 */ 161 162 if (file) { 163 fid = file->private_data; 164 if (!fid) 165 goto no_fid; 166 p9_fid_get(fid); 167 } else if (S_ISLNK(rreq->inode->i_mode)) { 168 dentry = d_find_any_alias(rreq->inode); 169 if (!dentry) 170 goto no_fid; 171 fid = v9fs_fid_lookup(dentry); 172 dput(dentry); 173 if (IS_ERR(fid)) 174 goto no_fid; 175 } else { 176 fid = v9fs_fid_find_inode(rreq->inode, writing, INVALID_UID, true); 177 if (!fid) 178 goto no_fid; 179 } 180 181 rreq->wsize = fid->clnt->msize - P9_IOHDRSZ; 182 if (fid->iounit) 183 rreq->wsize = min(rreq->wsize, fid->iounit); 184 185 /* we might need to read from a fid that was opened write-only 186 * for read-modify-write of page cache, use the writeback fid 187 * for that */ 188 WARN_ON(rreq->origin == NETFS_READ_FOR_WRITE && !(fid->mode & P9_ORDWR)); 189 rreq->netfs_priv = fid; 190 return 0; 191 192 no_fid: 193 WARN_ONCE(1, "folio expected an open fid inode->i_ino=%llx\n", 194 rreq->inode->i_ino); 195 return -EINVAL; 196 } 197 198 /** 199 * v9fs_free_request - Cleanup request initialized by v9fs_init_rreq 200 * @rreq: The I/O request to clean up 201 */ 202 static void v9fs_free_request(struct netfs_io_request *rreq) 203 { 204 struct p9_fid *fid = rreq->netfs_priv; 205 206 p9_fid_put(fid); 207 } 208 209 const struct netfs_request_ops v9fs_req_ops = { 210 .init_request = v9fs_init_request, 211 .free_request = v9fs_free_request, 212 .issue_read = v9fs_issue_read, 213 .begin_writeback = v9fs_begin_writeback, 214 .issue_write = v9fs_issue_write, 215 }; 216 217 const struct address_space_operations v9fs_addr_operations = { 218 .read_folio = netfs_read_folio, 219 .readahead = netfs_readahead, 220 .dirty_folio = netfs_dirty_folio, 221 .release_folio = netfs_release_folio, 222 .invalidate_folio = netfs_invalidate_folio, 223 .direct_IO = noop_direct_IO, 224 .writepages = netfs_writepages, 225 .migrate_folio = filemap_migrate_folio, 226 }; 227