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_req_issue_op - Issue a read from 9P 32 * @subreq: The read to make 33 */ 34 static void v9fs_req_issue_op(struct netfs_read_subrequest *subreq) 35 { 36 struct netfs_read_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_rreq - Initialise a read request 56 * @rreq: The read request 57 * @file: The file being read from 58 */ 59 static void v9fs_init_rreq(struct netfs_read_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 } 66 67 /** 68 * v9fs_req_cleanup - Cleanup request initialized by v9fs_init_rreq 69 * @mapping: unused mapping of request to cleanup 70 * @priv: private data to cleanup, a fid, guaranted non-null. 71 */ 72 static void v9fs_req_cleanup(struct address_space *mapping, void *priv) 73 { 74 struct p9_fid *fid = priv; 75 76 p9_client_clunk(fid); 77 } 78 79 /** 80 * v9fs_is_cache_enabled - Determine if caching is enabled for an inode 81 * @inode: The inode to check 82 */ 83 static bool v9fs_is_cache_enabled(struct inode *inode) 84 { 85 struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(inode)); 86 87 return fscache_cookie_enabled(cookie) && cookie->cache_priv; 88 } 89 90 /** 91 * v9fs_begin_cache_operation - Begin a cache operation for a read 92 * @rreq: The read request 93 */ 94 static int v9fs_begin_cache_operation(struct netfs_read_request *rreq) 95 { 96 #ifdef CONFIG_9P_FSCACHE 97 struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(rreq->inode)); 98 99 return fscache_begin_read_operation(&rreq->cache_resources, cookie); 100 #else 101 return -ENOBUFS; 102 #endif 103 } 104 105 static const struct netfs_read_request_ops v9fs_req_ops = { 106 .init_rreq = v9fs_init_rreq, 107 .is_cache_enabled = v9fs_is_cache_enabled, 108 .begin_cache_operation = v9fs_begin_cache_operation, 109 .issue_op = v9fs_req_issue_op, 110 .cleanup = v9fs_req_cleanup, 111 }; 112 113 /** 114 * v9fs_vfs_readpage - read an entire page in from 9P 115 * @file: file being read 116 * @page: structure to page 117 * 118 */ 119 static int v9fs_vfs_readpage(struct file *file, struct page *page) 120 { 121 struct folio *folio = page_folio(page); 122 123 return netfs_readpage(file, folio, &v9fs_req_ops, NULL); 124 } 125 126 /** 127 * v9fs_vfs_readahead - read a set of pages from 9P 128 * @ractl: The readahead parameters 129 */ 130 static void v9fs_vfs_readahead(struct readahead_control *ractl) 131 { 132 netfs_readahead(ractl, &v9fs_req_ops, NULL); 133 } 134 135 /** 136 * v9fs_release_page - release the private state associated with a page 137 * @page: The page to be released 138 * @gfp: The caller's allocation restrictions 139 * 140 * Returns 1 if the page can be released, false otherwise. 141 */ 142 143 static int v9fs_release_page(struct page *page, gfp_t gfp) 144 { 145 struct folio *folio = page_folio(page); 146 struct inode *inode = folio_inode(folio); 147 148 if (folio_test_private(folio)) 149 return 0; 150 #ifdef CONFIG_9P_FSCACHE 151 if (folio_test_fscache(folio)) { 152 if (current_is_kswapd() || !(gfp & __GFP_FS)) 153 return 0; 154 folio_wait_fscache(folio); 155 } 156 #endif 157 fscache_note_page_release(v9fs_inode_cookie(V9FS_I(inode))); 158 return 1; 159 } 160 161 static void v9fs_invalidate_folio(struct folio *folio, size_t offset, 162 size_t length) 163 { 164 folio_wait_fscache(folio); 165 } 166 167 static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error, 168 bool was_async) 169 { 170 struct v9fs_inode *v9inode = priv; 171 __le32 version; 172 173 if (IS_ERR_VALUE(transferred_or_error) && 174 transferred_or_error != -ENOBUFS) { 175 version = cpu_to_le32(v9inode->qid.version); 176 fscache_invalidate(v9fs_inode_cookie(v9inode), &version, 177 i_size_read(&v9inode->vfs_inode), 0); 178 } 179 } 180 181 static int v9fs_vfs_write_folio_locked(struct folio *folio) 182 { 183 struct inode *inode = folio_inode(folio); 184 struct v9fs_inode *v9inode = V9FS_I(inode); 185 struct fscache_cookie *cookie = v9fs_inode_cookie(v9inode); 186 loff_t start = folio_pos(folio); 187 loff_t i_size = i_size_read(inode); 188 struct iov_iter from; 189 size_t len = folio_size(folio); 190 int err; 191 192 if (start >= i_size) 193 return 0; /* Simultaneous truncation occurred */ 194 195 len = min_t(loff_t, i_size - start, len); 196 197 iov_iter_xarray(&from, WRITE, &folio_mapping(folio)->i_pages, start, len); 198 199 /* We should have writeback_fid always set */ 200 BUG_ON(!v9inode->writeback_fid); 201 202 folio_wait_fscache(folio); 203 folio_start_writeback(folio); 204 205 p9_client_write(v9inode->writeback_fid, start, &from, &err); 206 207 if (err == 0 && 208 fscache_cookie_enabled(cookie) && 209 test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags)) { 210 folio_start_fscache(folio); 211 fscache_write_to_cache(v9fs_inode_cookie(v9inode), 212 folio_mapping(folio), start, len, i_size, 213 v9fs_write_to_cache_done, v9inode, 214 true); 215 } 216 217 folio_end_writeback(folio); 218 return err; 219 } 220 221 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) 222 { 223 struct folio *folio = page_folio(page); 224 int retval; 225 226 p9_debug(P9_DEBUG_VFS, "folio %p\n", folio); 227 228 retval = v9fs_vfs_write_folio_locked(folio); 229 if (retval < 0) { 230 if (retval == -EAGAIN) { 231 folio_redirty_for_writepage(wbc, folio); 232 retval = 0; 233 } else { 234 mapping_set_error(folio_mapping(folio), retval); 235 } 236 } else 237 retval = 0; 238 239 folio_unlock(folio); 240 return retval; 241 } 242 243 static int v9fs_launder_folio(struct folio *folio) 244 { 245 int retval; 246 247 if (folio_clear_dirty_for_io(folio)) { 248 retval = v9fs_vfs_write_folio_locked(folio); 249 if (retval) 250 return retval; 251 } 252 folio_wait_fscache(folio); 253 return 0; 254 } 255 256 /** 257 * v9fs_direct_IO - 9P address space operation for direct I/O 258 * @iocb: target I/O control block 259 * @iter: The data/buffer to use 260 * 261 * The presence of v9fs_direct_IO() in the address space ops vector 262 * allowes open() O_DIRECT flags which would have failed otherwise. 263 * 264 * In the non-cached mode, we shunt off direct read and write requests before 265 * the VFS gets them, so this method should never be called. 266 * 267 * Direct IO is not 'yet' supported in the cached mode. Hence when 268 * this routine is called through generic_file_aio_read(), the read/write fails 269 * with an error. 270 * 271 */ 272 static ssize_t 273 v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 274 { 275 struct file *file = iocb->ki_filp; 276 loff_t pos = iocb->ki_pos; 277 ssize_t n; 278 int err = 0; 279 280 if (iov_iter_rw(iter) == WRITE) { 281 n = p9_client_write(file->private_data, pos, iter, &err); 282 if (n) { 283 struct inode *inode = file_inode(file); 284 loff_t i_size = i_size_read(inode); 285 286 if (pos + n > i_size) 287 inode_add_bytes(inode, pos + n - i_size); 288 } 289 } else { 290 n = p9_client_read(file->private_data, pos, iter, &err); 291 } 292 return n ? n : err; 293 } 294 295 static int v9fs_write_begin(struct file *filp, struct address_space *mapping, 296 loff_t pos, unsigned int len, unsigned int flags, 297 struct page **subpagep, void **fsdata) 298 { 299 int retval; 300 struct folio *folio; 301 struct v9fs_inode *v9inode = V9FS_I(mapping->host); 302 303 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 304 305 BUG_ON(!v9inode->writeback_fid); 306 307 /* Prefetch area to be written into the cache if we're caching this 308 * file. We need to do this before we get a lock on the page in case 309 * there's more than one writer competing for the same cache block. 310 */ 311 retval = netfs_write_begin(filp, mapping, pos, len, flags, &folio, fsdata, 312 &v9fs_req_ops, NULL); 313 if (retval < 0) 314 return retval; 315 316 *subpagep = &folio->page; 317 return retval; 318 } 319 320 static int v9fs_write_end(struct file *filp, struct address_space *mapping, 321 loff_t pos, unsigned int len, unsigned int copied, 322 struct page *subpage, void *fsdata) 323 { 324 loff_t last_pos = pos + copied; 325 struct folio *folio = page_folio(subpage); 326 struct inode *inode = mapping->host; 327 struct v9fs_inode *v9inode = V9FS_I(inode); 328 329 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 330 331 if (!folio_test_uptodate(folio)) { 332 if (unlikely(copied < len)) { 333 copied = 0; 334 goto out; 335 } 336 337 folio_mark_uptodate(folio); 338 } 339 340 /* 341 * No need to use i_size_read() here, the i_size 342 * cannot change under us because we hold the i_mutex. 343 */ 344 if (last_pos > inode->i_size) { 345 inode_add_bytes(inode, last_pos - inode->i_size); 346 i_size_write(inode, last_pos); 347 fscache_update_cookie(v9fs_inode_cookie(v9inode), NULL, &last_pos); 348 } 349 folio_mark_dirty(folio); 350 out: 351 folio_unlock(folio); 352 folio_put(folio); 353 354 return copied; 355 } 356 357 #ifdef CONFIG_9P_FSCACHE 358 /* 359 * Mark a page as having been made dirty and thus needing writeback. We also 360 * need to pin the cache object to write back to. 361 */ 362 static bool v9fs_dirty_folio(struct address_space *mapping, struct folio *folio) 363 { 364 struct v9fs_inode *v9inode = V9FS_I(mapping->host); 365 366 return fscache_dirty_folio(mapping, folio, v9fs_inode_cookie(v9inode)); 367 } 368 #else 369 #define v9fs_dirty_folio filemap_dirty_folio 370 #endif 371 372 const struct address_space_operations v9fs_addr_operations = { 373 .readpage = v9fs_vfs_readpage, 374 .readahead = v9fs_vfs_readahead, 375 .dirty_folio = v9fs_dirty_folio, 376 .writepage = v9fs_vfs_writepage, 377 .write_begin = v9fs_write_begin, 378 .write_end = v9fs_write_end, 379 .releasepage = v9fs_release_page, 380 .invalidate_folio = v9fs_invalidate_folio, 381 .launder_folio = v9fs_launder_folio, 382 .direct_IO = v9fs_direct_IO, 383 }; 384