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 /** 162 * v9fs_invalidate_page - Invalidate a page completely or partially 163 * @page: The page to be invalidated 164 * @offset: offset of the invalidated region 165 * @length: length of the invalidated region 166 */ 167 168 static void v9fs_invalidate_page(struct page *page, unsigned int offset, 169 unsigned int length) 170 { 171 struct folio *folio = page_folio(page); 172 173 folio_wait_fscache(folio); 174 } 175 176 static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error, 177 bool was_async) 178 { 179 struct v9fs_inode *v9inode = priv; 180 __le32 version; 181 182 if (IS_ERR_VALUE(transferred_or_error) && 183 transferred_or_error != -ENOBUFS) { 184 version = cpu_to_le32(v9inode->qid.version); 185 fscache_invalidate(v9fs_inode_cookie(v9inode), &version, 186 i_size_read(&v9inode->vfs_inode), 0); 187 } 188 } 189 190 static int v9fs_vfs_write_folio_locked(struct folio *folio) 191 { 192 struct inode *inode = folio_inode(folio); 193 struct v9fs_inode *v9inode = V9FS_I(inode); 194 struct fscache_cookie *cookie = v9fs_inode_cookie(v9inode); 195 loff_t start = folio_pos(folio); 196 loff_t i_size = i_size_read(inode); 197 struct iov_iter from; 198 size_t len = folio_size(folio); 199 int err; 200 201 if (start >= i_size) 202 return 0; /* Simultaneous truncation occurred */ 203 204 len = min_t(loff_t, i_size - start, len); 205 206 iov_iter_xarray(&from, WRITE, &folio_mapping(folio)->i_pages, start, len); 207 208 /* We should have writeback_fid always set */ 209 BUG_ON(!v9inode->writeback_fid); 210 211 folio_wait_fscache(folio); 212 folio_start_writeback(folio); 213 214 p9_client_write(v9inode->writeback_fid, start, &from, &err); 215 216 if (err == 0 && 217 fscache_cookie_enabled(cookie) && 218 test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags)) { 219 folio_start_fscache(folio); 220 fscache_write_to_cache(v9fs_inode_cookie(v9inode), 221 folio_mapping(folio), start, len, i_size, 222 v9fs_write_to_cache_done, v9inode, 223 true); 224 } 225 226 folio_end_writeback(folio); 227 return err; 228 } 229 230 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) 231 { 232 struct folio *folio = page_folio(page); 233 int retval; 234 235 p9_debug(P9_DEBUG_VFS, "folio %p\n", folio); 236 237 retval = v9fs_vfs_write_folio_locked(folio); 238 if (retval < 0) { 239 if (retval == -EAGAIN) { 240 folio_redirty_for_writepage(wbc, folio); 241 retval = 0; 242 } else { 243 mapping_set_error(folio_mapping(folio), retval); 244 } 245 } else 246 retval = 0; 247 248 folio_unlock(folio); 249 return retval; 250 } 251 252 /** 253 * v9fs_launder_page - Writeback a dirty page 254 * @page: The page to be cleaned up 255 * 256 * Returns 0 on success. 257 */ 258 259 static int v9fs_launder_page(struct page *page) 260 { 261 struct folio *folio = page_folio(page); 262 int retval; 263 264 if (folio_clear_dirty_for_io(folio)) { 265 retval = v9fs_vfs_write_folio_locked(folio); 266 if (retval) 267 return retval; 268 } 269 folio_wait_fscache(folio); 270 return 0; 271 } 272 273 /** 274 * v9fs_direct_IO - 9P address space operation for direct I/O 275 * @iocb: target I/O control block 276 * @iter: The data/buffer to use 277 * 278 * The presence of v9fs_direct_IO() in the address space ops vector 279 * allowes open() O_DIRECT flags which would have failed otherwise. 280 * 281 * In the non-cached mode, we shunt off direct read and write requests before 282 * the VFS gets them, so this method should never be called. 283 * 284 * Direct IO is not 'yet' supported in the cached mode. Hence when 285 * this routine is called through generic_file_aio_read(), the read/write fails 286 * with an error. 287 * 288 */ 289 static ssize_t 290 v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 291 { 292 struct file *file = iocb->ki_filp; 293 loff_t pos = iocb->ki_pos; 294 ssize_t n; 295 int err = 0; 296 297 if (iov_iter_rw(iter) == WRITE) { 298 n = p9_client_write(file->private_data, pos, iter, &err); 299 if (n) { 300 struct inode *inode = file_inode(file); 301 loff_t i_size = i_size_read(inode); 302 303 if (pos + n > i_size) 304 inode_add_bytes(inode, pos + n - i_size); 305 } 306 } else { 307 n = p9_client_read(file->private_data, pos, iter, &err); 308 } 309 return n ? n : err; 310 } 311 312 static int v9fs_write_begin(struct file *filp, struct address_space *mapping, 313 loff_t pos, unsigned int len, unsigned int flags, 314 struct page **subpagep, void **fsdata) 315 { 316 int retval; 317 struct folio *folio; 318 struct v9fs_inode *v9inode = V9FS_I(mapping->host); 319 320 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 321 322 BUG_ON(!v9inode->writeback_fid); 323 324 /* Prefetch area to be written into the cache if we're caching this 325 * file. We need to do this before we get a lock on the page in case 326 * there's more than one writer competing for the same cache block. 327 */ 328 retval = netfs_write_begin(filp, mapping, pos, len, flags, &folio, fsdata, 329 &v9fs_req_ops, NULL); 330 if (retval < 0) 331 return retval; 332 333 *subpagep = &folio->page; 334 return retval; 335 } 336 337 static int v9fs_write_end(struct file *filp, struct address_space *mapping, 338 loff_t pos, unsigned int len, unsigned int copied, 339 struct page *subpage, void *fsdata) 340 { 341 loff_t last_pos = pos + copied; 342 struct folio *folio = page_folio(subpage); 343 struct inode *inode = mapping->host; 344 struct v9fs_inode *v9inode = V9FS_I(inode); 345 346 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 347 348 if (!folio_test_uptodate(folio)) { 349 if (unlikely(copied < len)) { 350 copied = 0; 351 goto out; 352 } 353 354 folio_mark_uptodate(folio); 355 } 356 357 /* 358 * No need to use i_size_read() here, the i_size 359 * cannot change under us because we hold the i_mutex. 360 */ 361 if (last_pos > inode->i_size) { 362 inode_add_bytes(inode, last_pos - inode->i_size); 363 i_size_write(inode, last_pos); 364 fscache_update_cookie(v9fs_inode_cookie(v9inode), NULL, &last_pos); 365 } 366 folio_mark_dirty(folio); 367 out: 368 folio_unlock(folio); 369 folio_put(folio); 370 371 return copied; 372 } 373 374 #ifdef CONFIG_9P_FSCACHE 375 /* 376 * Mark a page as having been made dirty and thus needing writeback. We also 377 * need to pin the cache object to write back to. 378 */ 379 static int v9fs_set_page_dirty(struct page *page) 380 { 381 struct v9fs_inode *v9inode = V9FS_I(page->mapping->host); 382 383 return fscache_set_page_dirty(page, v9fs_inode_cookie(v9inode)); 384 } 385 #else 386 #define v9fs_set_page_dirty __set_page_dirty_nobuffers 387 #endif 388 389 const struct address_space_operations v9fs_addr_operations = { 390 .readpage = v9fs_vfs_readpage, 391 .readahead = v9fs_vfs_readahead, 392 .set_page_dirty = v9fs_set_page_dirty, 393 .writepage = v9fs_vfs_writepage, 394 .write_begin = v9fs_write_begin, 395 .write_end = v9fs_write_end, 396 .releasepage = v9fs_release_page, 397 .invalidatepage = v9fs_invalidate_page, 398 .launder_page = v9fs_launder_page, 399 .direct_IO = v9fs_direct_IO, 400 }; 401