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/sched.h> 18 #include <linux/swap.h> 19 #include <linux/uio.h> 20 #include <linux/netfs.h> 21 #include <net/9p/9p.h> 22 #include <net/9p/client.h> 23 24 #include "v9fs.h" 25 #include "v9fs_vfs.h" 26 #include "cache.h" 27 #include "fid.h" 28 29 /** 30 * v9fs_issue_read - Issue a read from 9P 31 * @subreq: The read to make 32 */ 33 static void v9fs_issue_read(struct netfs_io_subrequest *subreq) 34 { 35 struct netfs_io_request *rreq = subreq->rreq; 36 struct p9_fid *fid = rreq->netfs_priv; 37 struct iov_iter to; 38 loff_t pos = subreq->start + subreq->transferred; 39 size_t len = subreq->len - subreq->transferred; 40 int total, err; 41 42 iov_iter_xarray(&to, ITER_DEST, &rreq->mapping->i_pages, pos, len); 43 44 total = p9_client_read(fid, pos, &to, &err); 45 46 /* if we just extended the file size, any portion not in 47 * cache won't be on server and is zeroes */ 48 __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags); 49 50 netfs_subreq_terminated(subreq, err ?: total, false); 51 } 52 53 /** 54 * v9fs_init_request - Initialise a read request 55 * @rreq: The read request 56 * @file: The file being read from 57 */ 58 static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file) 59 { 60 struct inode *inode = file_inode(file); 61 struct v9fs_inode *v9inode = V9FS_I(inode); 62 struct p9_fid *fid = file->private_data; 63 64 BUG_ON(!fid); 65 66 /* we might need to read from a fid that was opened write-only 67 * for read-modify-write of page cache, use the writeback fid 68 * for that */ 69 if (rreq->origin == NETFS_READ_FOR_WRITE && 70 (fid->mode & O_ACCMODE) == O_WRONLY) { 71 fid = v9inode->writeback_fid; 72 BUG_ON(!fid); 73 } 74 75 p9_fid_get(fid); 76 rreq->netfs_priv = fid; 77 return 0; 78 } 79 80 /** 81 * v9fs_free_request - Cleanup request initialized by v9fs_init_rreq 82 * @rreq: The I/O request to clean up 83 */ 84 static void v9fs_free_request(struct netfs_io_request *rreq) 85 { 86 struct p9_fid *fid = rreq->netfs_priv; 87 88 p9_fid_put(fid); 89 } 90 91 /** 92 * v9fs_begin_cache_operation - Begin a cache operation for a read 93 * @rreq: The read request 94 */ 95 static int v9fs_begin_cache_operation(struct netfs_io_request *rreq) 96 { 97 #ifdef CONFIG_9P_FSCACHE 98 struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(rreq->inode)); 99 100 return fscache_begin_read_operation(&rreq->cache_resources, cookie); 101 #else 102 return -ENOBUFS; 103 #endif 104 } 105 106 const struct netfs_request_ops v9fs_req_ops = { 107 .init_request = v9fs_init_request, 108 .free_request = v9fs_free_request, 109 .begin_cache_operation = v9fs_begin_cache_operation, 110 .issue_read = v9fs_issue_read, 111 }; 112 113 /** 114 * v9fs_release_folio - release the private state associated with a folio 115 * @folio: The folio to be released 116 * @gfp: The caller's allocation restrictions 117 * 118 * Returns true if the page can be released, false otherwise. 119 */ 120 121 static bool v9fs_release_folio(struct folio *folio, gfp_t gfp) 122 { 123 struct inode *inode = folio_inode(folio); 124 125 if (folio_test_private(folio)) 126 return false; 127 #ifdef CONFIG_9P_FSCACHE 128 if (folio_test_fscache(folio)) { 129 if (current_is_kswapd() || !(gfp & __GFP_FS)) 130 return false; 131 folio_wait_fscache(folio); 132 } 133 #endif 134 fscache_note_page_release(v9fs_inode_cookie(V9FS_I(inode))); 135 return true; 136 } 137 138 static void v9fs_invalidate_folio(struct folio *folio, size_t offset, 139 size_t length) 140 { 141 folio_wait_fscache(folio); 142 } 143 144 static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error, 145 bool was_async) 146 { 147 struct v9fs_inode *v9inode = priv; 148 __le32 version; 149 150 if (IS_ERR_VALUE(transferred_or_error) && 151 transferred_or_error != -ENOBUFS) { 152 version = cpu_to_le32(v9inode->qid.version); 153 fscache_invalidate(v9fs_inode_cookie(v9inode), &version, 154 i_size_read(&v9inode->netfs.inode), 0); 155 } 156 } 157 158 static int v9fs_vfs_write_folio_locked(struct folio *folio) 159 { 160 struct inode *inode = folio_inode(folio); 161 struct v9fs_inode *v9inode = V9FS_I(inode); 162 struct fscache_cookie *cookie = v9fs_inode_cookie(v9inode); 163 loff_t start = folio_pos(folio); 164 loff_t i_size = i_size_read(inode); 165 struct iov_iter from; 166 size_t len = folio_size(folio); 167 int err; 168 169 if (start >= i_size) 170 return 0; /* Simultaneous truncation occurred */ 171 172 len = min_t(loff_t, i_size - start, len); 173 174 iov_iter_xarray(&from, ITER_SOURCE, &folio_mapping(folio)->i_pages, start, len); 175 176 /* We should have writeback_fid always set */ 177 BUG_ON(!v9inode->writeback_fid); 178 179 folio_wait_fscache(folio); 180 folio_start_writeback(folio); 181 182 p9_client_write(v9inode->writeback_fid, start, &from, &err); 183 184 if (err == 0 && 185 fscache_cookie_enabled(cookie) && 186 test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags)) { 187 folio_start_fscache(folio); 188 fscache_write_to_cache(v9fs_inode_cookie(v9inode), 189 folio_mapping(folio), start, len, i_size, 190 v9fs_write_to_cache_done, v9inode, 191 true); 192 } 193 194 folio_end_writeback(folio); 195 return err; 196 } 197 198 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) 199 { 200 struct folio *folio = page_folio(page); 201 int retval; 202 203 p9_debug(P9_DEBUG_VFS, "folio %p\n", folio); 204 205 retval = v9fs_vfs_write_folio_locked(folio); 206 if (retval < 0) { 207 if (retval == -EAGAIN) { 208 folio_redirty_for_writepage(wbc, folio); 209 retval = 0; 210 } else { 211 mapping_set_error(folio_mapping(folio), retval); 212 } 213 } else 214 retval = 0; 215 216 folio_unlock(folio); 217 return retval; 218 } 219 220 static int v9fs_launder_folio(struct folio *folio) 221 { 222 int retval; 223 224 if (folio_clear_dirty_for_io(folio)) { 225 retval = v9fs_vfs_write_folio_locked(folio); 226 if (retval) 227 return retval; 228 } 229 folio_wait_fscache(folio); 230 return 0; 231 } 232 233 /** 234 * v9fs_direct_IO - 9P address space operation for direct I/O 235 * @iocb: target I/O control block 236 * @iter: The data/buffer to use 237 * 238 * The presence of v9fs_direct_IO() in the address space ops vector 239 * allowes open() O_DIRECT flags which would have failed otherwise. 240 * 241 * In the non-cached mode, we shunt off direct read and write requests before 242 * the VFS gets them, so this method should never be called. 243 * 244 * Direct IO is not 'yet' supported in the cached mode. Hence when 245 * this routine is called through generic_file_aio_read(), the read/write fails 246 * with an error. 247 * 248 */ 249 static ssize_t 250 v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 251 { 252 struct file *file = iocb->ki_filp; 253 loff_t pos = iocb->ki_pos; 254 ssize_t n; 255 int err = 0; 256 257 if (iov_iter_rw(iter) == WRITE) { 258 n = p9_client_write(file->private_data, pos, iter, &err); 259 if (n) { 260 struct inode *inode = file_inode(file); 261 loff_t i_size = i_size_read(inode); 262 263 if (pos + n > i_size) 264 inode_add_bytes(inode, pos + n - i_size); 265 } 266 } else { 267 n = p9_client_read(file->private_data, pos, iter, &err); 268 } 269 return n ? n : err; 270 } 271 272 static int v9fs_write_begin(struct file *filp, struct address_space *mapping, 273 loff_t pos, unsigned int len, 274 struct page **subpagep, void **fsdata) 275 { 276 int retval; 277 struct folio *folio; 278 struct v9fs_inode *v9inode = V9FS_I(mapping->host); 279 280 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 281 282 BUG_ON(!v9inode->writeback_fid); 283 284 /* Prefetch area to be written into the cache if we're caching this 285 * file. We need to do this before we get a lock on the page in case 286 * there's more than one writer competing for the same cache block. 287 */ 288 retval = netfs_write_begin(&v9inode->netfs, filp, mapping, pos, len, &folio, fsdata); 289 if (retval < 0) 290 return retval; 291 292 *subpagep = &folio->page; 293 return retval; 294 } 295 296 static int v9fs_write_end(struct file *filp, struct address_space *mapping, 297 loff_t pos, unsigned int len, unsigned int copied, 298 struct page *subpage, void *fsdata) 299 { 300 loff_t last_pos = pos + copied; 301 struct folio *folio = page_folio(subpage); 302 struct inode *inode = mapping->host; 303 struct v9fs_inode *v9inode = V9FS_I(inode); 304 305 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 306 307 if (!folio_test_uptodate(folio)) { 308 if (unlikely(copied < len)) { 309 copied = 0; 310 goto out; 311 } 312 313 folio_mark_uptodate(folio); 314 } 315 316 /* 317 * No need to use i_size_read() here, the i_size 318 * cannot change under us because we hold the i_mutex. 319 */ 320 if (last_pos > inode->i_size) { 321 inode_add_bytes(inode, last_pos - inode->i_size); 322 i_size_write(inode, last_pos); 323 fscache_update_cookie(v9fs_inode_cookie(v9inode), NULL, &last_pos); 324 } 325 folio_mark_dirty(folio); 326 out: 327 folio_unlock(folio); 328 folio_put(folio); 329 330 return copied; 331 } 332 333 #ifdef CONFIG_9P_FSCACHE 334 /* 335 * Mark a page as having been made dirty and thus needing writeback. We also 336 * need to pin the cache object to write back to. 337 */ 338 static bool v9fs_dirty_folio(struct address_space *mapping, struct folio *folio) 339 { 340 struct v9fs_inode *v9inode = V9FS_I(mapping->host); 341 342 return fscache_dirty_folio(mapping, folio, v9fs_inode_cookie(v9inode)); 343 } 344 #else 345 #define v9fs_dirty_folio filemap_dirty_folio 346 #endif 347 348 const struct address_space_operations v9fs_addr_operations = { 349 .read_folio = netfs_read_folio, 350 .readahead = netfs_readahead, 351 .dirty_folio = v9fs_dirty_folio, 352 .writepage = v9fs_vfs_writepage, 353 .write_begin = v9fs_write_begin, 354 .write_end = v9fs_write_end, 355 .release_folio = v9fs_release_folio, 356 .invalidate_folio = v9fs_invalidate_folio, 357 .launder_folio = v9fs_launder_folio, 358 .direct_IO = v9fs_direct_IO, 359 }; 360