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/inet.h> 16 #include <linux/pagemap.h> 17 #include <linux/idr.h> 18 #include <linux/sched.h> 19 #include <linux/swap.h> 20 #include <linux/uio.h> 21 #include <linux/netfs.h> 22 #include <net/9p/9p.h> 23 #include <net/9p/client.h> 24 25 #include "v9fs.h" 26 #include "v9fs_vfs.h" 27 #include "cache.h" 28 #include "fid.h" 29 30 /** 31 * v9fs_issue_read - Issue a read from 9P 32 * @subreq: The read to make 33 */ 34 static void v9fs_issue_read(struct netfs_io_subrequest *subreq) 35 { 36 struct netfs_io_request *rreq = subreq->rreq; 37 struct p9_fid *fid = rreq->netfs_priv; 38 struct iov_iter to; 39 loff_t pos = subreq->start + subreq->transferred; 40 size_t len = subreq->len - subreq->transferred; 41 int total, err; 42 43 iov_iter_xarray(&to, READ, &rreq->mapping->i_pages, pos, len); 44 45 total = p9_client_read(fid, pos, &to, &err); 46 47 /* if we just extended the file size, any portion not in 48 * cache won't be on server and is zeroes */ 49 __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags); 50 51 netfs_subreq_terminated(subreq, err ?: total, false); 52 } 53 54 /** 55 * v9fs_init_request - Initialise a read request 56 * @rreq: The read request 57 * @file: The file being read from 58 */ 59 static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file) 60 { 61 struct p9_fid *fid = file->private_data; 62 63 refcount_inc(&fid->count); 64 rreq->netfs_priv = fid; 65 return 0; 66 } 67 68 /** 69 * v9fs_free_request - Cleanup request initialized by v9fs_init_rreq 70 * @rreq: The I/O request to clean up 71 */ 72 static void v9fs_free_request(struct netfs_io_request *rreq) 73 { 74 struct p9_fid *fid = rreq->netfs_priv; 75 76 p9_client_clunk(fid); 77 } 78 79 /** 80 * v9fs_begin_cache_operation - Begin a cache operation for a read 81 * @rreq: The read request 82 */ 83 static int v9fs_begin_cache_operation(struct netfs_io_request *rreq) 84 { 85 #ifdef CONFIG_9P_FSCACHE 86 struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(rreq->inode)); 87 88 return fscache_begin_read_operation(&rreq->cache_resources, cookie); 89 #else 90 return -ENOBUFS; 91 #endif 92 } 93 94 const struct netfs_request_ops v9fs_req_ops = { 95 .init_request = v9fs_init_request, 96 .free_request = v9fs_free_request, 97 .begin_cache_operation = v9fs_begin_cache_operation, 98 .issue_read = v9fs_issue_read, 99 }; 100 101 /** 102 * v9fs_release_folio - release the private state associated with a folio 103 * @folio: The folio to be released 104 * @gfp: The caller's allocation restrictions 105 * 106 * Returns true if the page can be released, false otherwise. 107 */ 108 109 static bool v9fs_release_folio(struct folio *folio, gfp_t gfp) 110 { 111 struct inode *inode = folio_inode(folio); 112 113 if (folio_test_private(folio)) 114 return false; 115 #ifdef CONFIG_9P_FSCACHE 116 if (folio_test_fscache(folio)) { 117 if (current_is_kswapd() || !(gfp & __GFP_FS)) 118 return false; 119 folio_wait_fscache(folio); 120 } 121 #endif 122 fscache_note_page_release(v9fs_inode_cookie(V9FS_I(inode))); 123 return true; 124 } 125 126 static void v9fs_invalidate_folio(struct folio *folio, size_t offset, 127 size_t length) 128 { 129 folio_wait_fscache(folio); 130 } 131 132 static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error, 133 bool was_async) 134 { 135 struct v9fs_inode *v9inode = priv; 136 __le32 version; 137 138 if (IS_ERR_VALUE(transferred_or_error) && 139 transferred_or_error != -ENOBUFS) { 140 version = cpu_to_le32(v9inode->qid.version); 141 fscache_invalidate(v9fs_inode_cookie(v9inode), &version, 142 i_size_read(&v9inode->netfs.inode), 0); 143 } 144 } 145 146 static int v9fs_vfs_write_folio_locked(struct folio *folio) 147 { 148 struct inode *inode = folio_inode(folio); 149 struct v9fs_inode *v9inode = V9FS_I(inode); 150 struct fscache_cookie *cookie = v9fs_inode_cookie(v9inode); 151 loff_t start = folio_pos(folio); 152 loff_t i_size = i_size_read(inode); 153 struct iov_iter from; 154 size_t len = folio_size(folio); 155 int err; 156 157 if (start >= i_size) 158 return 0; /* Simultaneous truncation occurred */ 159 160 len = min_t(loff_t, i_size - start, len); 161 162 iov_iter_xarray(&from, WRITE, &folio_mapping(folio)->i_pages, start, len); 163 164 /* We should have writeback_fid always set */ 165 BUG_ON(!v9inode->writeback_fid); 166 167 folio_wait_fscache(folio); 168 folio_start_writeback(folio); 169 170 p9_client_write(v9inode->writeback_fid, start, &from, &err); 171 172 if (err == 0 && 173 fscache_cookie_enabled(cookie) && 174 test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags)) { 175 folio_start_fscache(folio); 176 fscache_write_to_cache(v9fs_inode_cookie(v9inode), 177 folio_mapping(folio), start, len, i_size, 178 v9fs_write_to_cache_done, v9inode, 179 true); 180 } 181 182 folio_end_writeback(folio); 183 return err; 184 } 185 186 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) 187 { 188 struct folio *folio = page_folio(page); 189 int retval; 190 191 p9_debug(P9_DEBUG_VFS, "folio %p\n", folio); 192 193 retval = v9fs_vfs_write_folio_locked(folio); 194 if (retval < 0) { 195 if (retval == -EAGAIN) { 196 folio_redirty_for_writepage(wbc, folio); 197 retval = 0; 198 } else { 199 mapping_set_error(folio_mapping(folio), retval); 200 } 201 } else 202 retval = 0; 203 204 folio_unlock(folio); 205 return retval; 206 } 207 208 static int v9fs_launder_folio(struct folio *folio) 209 { 210 int retval; 211 212 if (folio_clear_dirty_for_io(folio)) { 213 retval = v9fs_vfs_write_folio_locked(folio); 214 if (retval) 215 return retval; 216 } 217 folio_wait_fscache(folio); 218 return 0; 219 } 220 221 /** 222 * v9fs_direct_IO - 9P address space operation for direct I/O 223 * @iocb: target I/O control block 224 * @iter: The data/buffer to use 225 * 226 * The presence of v9fs_direct_IO() in the address space ops vector 227 * allowes open() O_DIRECT flags which would have failed otherwise. 228 * 229 * In the non-cached mode, we shunt off direct read and write requests before 230 * the VFS gets them, so this method should never be called. 231 * 232 * Direct IO is not 'yet' supported in the cached mode. Hence when 233 * this routine is called through generic_file_aio_read(), the read/write fails 234 * with an error. 235 * 236 */ 237 static ssize_t 238 v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 239 { 240 struct file *file = iocb->ki_filp; 241 loff_t pos = iocb->ki_pos; 242 ssize_t n; 243 int err = 0; 244 245 if (iov_iter_rw(iter) == WRITE) { 246 n = p9_client_write(file->private_data, pos, iter, &err); 247 if (n) { 248 struct inode *inode = file_inode(file); 249 loff_t i_size = i_size_read(inode); 250 251 if (pos + n > i_size) 252 inode_add_bytes(inode, pos + n - i_size); 253 } 254 } else { 255 n = p9_client_read(file->private_data, pos, iter, &err); 256 } 257 return n ? n : err; 258 } 259 260 static int v9fs_write_begin(struct file *filp, struct address_space *mapping, 261 loff_t pos, unsigned int len, 262 struct page **subpagep, void **fsdata) 263 { 264 int retval; 265 struct folio *folio; 266 struct v9fs_inode *v9inode = V9FS_I(mapping->host); 267 268 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 269 270 BUG_ON(!v9inode->writeback_fid); 271 272 /* Prefetch area to be written into the cache if we're caching this 273 * file. We need to do this before we get a lock on the page in case 274 * there's more than one writer competing for the same cache block. 275 */ 276 retval = netfs_write_begin(&v9inode->netfs, filp, mapping, pos, len, &folio, fsdata); 277 if (retval < 0) 278 return retval; 279 280 *subpagep = &folio->page; 281 return retval; 282 } 283 284 static int v9fs_write_end(struct file *filp, struct address_space *mapping, 285 loff_t pos, unsigned int len, unsigned int copied, 286 struct page *subpage, void *fsdata) 287 { 288 loff_t last_pos = pos + copied; 289 struct folio *folio = page_folio(subpage); 290 struct inode *inode = mapping->host; 291 struct v9fs_inode *v9inode = V9FS_I(inode); 292 293 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 294 295 if (!folio_test_uptodate(folio)) { 296 if (unlikely(copied < len)) { 297 copied = 0; 298 goto out; 299 } 300 301 folio_mark_uptodate(folio); 302 } 303 304 /* 305 * No need to use i_size_read() here, the i_size 306 * cannot change under us because we hold the i_mutex. 307 */ 308 if (last_pos > inode->i_size) { 309 inode_add_bytes(inode, last_pos - inode->i_size); 310 i_size_write(inode, last_pos); 311 fscache_update_cookie(v9fs_inode_cookie(v9inode), NULL, &last_pos); 312 } 313 folio_mark_dirty(folio); 314 out: 315 folio_unlock(folio); 316 folio_put(folio); 317 318 return copied; 319 } 320 321 #ifdef CONFIG_9P_FSCACHE 322 /* 323 * Mark a page as having been made dirty and thus needing writeback. We also 324 * need to pin the cache object to write back to. 325 */ 326 static bool v9fs_dirty_folio(struct address_space *mapping, struct folio *folio) 327 { 328 struct v9fs_inode *v9inode = V9FS_I(mapping->host); 329 330 return fscache_dirty_folio(mapping, folio, v9fs_inode_cookie(v9inode)); 331 } 332 #else 333 #define v9fs_dirty_folio filemap_dirty_folio 334 #endif 335 336 const struct address_space_operations v9fs_addr_operations = { 337 .read_folio = netfs_read_folio, 338 .readahead = netfs_readahead, 339 .dirty_folio = v9fs_dirty_folio, 340 .writepage = v9fs_vfs_writepage, 341 .write_begin = v9fs_write_begin, 342 .write_end = v9fs_write_end, 343 .release_folio = v9fs_release_folio, 344 .invalidate_folio = v9fs_invalidate_folio, 345 .launder_folio = v9fs_launder_folio, 346 .direct_IO = v9fs_direct_IO, 347 }; 348