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 inode *inode = file_inode(file); 62 struct v9fs_inode *v9inode = V9FS_I(inode); 63 struct p9_fid *fid = file->private_data; 64 65 BUG_ON(!fid); 66 67 /* we might need to read from a fid that was opened write-only 68 * for read-modify-write of page cache, use the writeback fid 69 * for that */ 70 if (rreq->origin == NETFS_READ_FOR_WRITE && 71 (fid->mode & O_ACCMODE) == O_WRONLY) { 72 fid = v9inode->writeback_fid; 73 BUG_ON(!fid); 74 } 75 76 refcount_inc(&fid->count); 77 rreq->netfs_priv = fid; 78 return 0; 79 } 80 81 /** 82 * v9fs_free_request - Cleanup request initialized by v9fs_init_rreq 83 * @rreq: The I/O request to clean up 84 */ 85 static void v9fs_free_request(struct netfs_io_request *rreq) 86 { 87 struct p9_fid *fid = rreq->netfs_priv; 88 89 p9_client_clunk(fid); 90 } 91 92 /** 93 * v9fs_begin_cache_operation - Begin a cache operation for a read 94 * @rreq: The read request 95 */ 96 static int v9fs_begin_cache_operation(struct netfs_io_request *rreq) 97 { 98 #ifdef CONFIG_9P_FSCACHE 99 struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(rreq->inode)); 100 101 return fscache_begin_read_operation(&rreq->cache_resources, cookie); 102 #else 103 return -ENOBUFS; 104 #endif 105 } 106 107 const struct netfs_request_ops v9fs_req_ops = { 108 .init_request = v9fs_init_request, 109 .free_request = v9fs_free_request, 110 .begin_cache_operation = v9fs_begin_cache_operation, 111 .issue_read = v9fs_issue_read, 112 }; 113 114 /** 115 * v9fs_release_folio - release the private state associated with a folio 116 * @folio: The folio to be released 117 * @gfp: The caller's allocation restrictions 118 * 119 * Returns true if the page can be released, false otherwise. 120 */ 121 122 static bool v9fs_release_folio(struct folio *folio, gfp_t gfp) 123 { 124 struct inode *inode = folio_inode(folio); 125 126 if (folio_test_private(folio)) 127 return false; 128 #ifdef CONFIG_9P_FSCACHE 129 if (folio_test_fscache(folio)) { 130 if (current_is_kswapd() || !(gfp & __GFP_FS)) 131 return false; 132 folio_wait_fscache(folio); 133 } 134 #endif 135 fscache_note_page_release(v9fs_inode_cookie(V9FS_I(inode))); 136 return true; 137 } 138 139 static void v9fs_invalidate_folio(struct folio *folio, size_t offset, 140 size_t length) 141 { 142 folio_wait_fscache(folio); 143 } 144 145 static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error, 146 bool was_async) 147 { 148 struct v9fs_inode *v9inode = priv; 149 __le32 version; 150 151 if (IS_ERR_VALUE(transferred_or_error) && 152 transferred_or_error != -ENOBUFS) { 153 version = cpu_to_le32(v9inode->qid.version); 154 fscache_invalidate(v9fs_inode_cookie(v9inode), &version, 155 i_size_read(&v9inode->netfs.inode), 0); 156 } 157 } 158 159 static int v9fs_vfs_write_folio_locked(struct folio *folio) 160 { 161 struct inode *inode = folio_inode(folio); 162 struct v9fs_inode *v9inode = V9FS_I(inode); 163 struct fscache_cookie *cookie = v9fs_inode_cookie(v9inode); 164 loff_t start = folio_pos(folio); 165 loff_t i_size = i_size_read(inode); 166 struct iov_iter from; 167 size_t len = folio_size(folio); 168 int err; 169 170 if (start >= i_size) 171 return 0; /* Simultaneous truncation occurred */ 172 173 len = min_t(loff_t, i_size - start, len); 174 175 iov_iter_xarray(&from, WRITE, &folio_mapping(folio)->i_pages, start, len); 176 177 /* We should have writeback_fid always set */ 178 BUG_ON(!v9inode->writeback_fid); 179 180 folio_wait_fscache(folio); 181 folio_start_writeback(folio); 182 183 p9_client_write(v9inode->writeback_fid, start, &from, &err); 184 185 if (err == 0 && 186 fscache_cookie_enabled(cookie) && 187 test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags)) { 188 folio_start_fscache(folio); 189 fscache_write_to_cache(v9fs_inode_cookie(v9inode), 190 folio_mapping(folio), start, len, i_size, 191 v9fs_write_to_cache_done, v9inode, 192 true); 193 } 194 195 folio_end_writeback(folio); 196 return err; 197 } 198 199 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) 200 { 201 struct folio *folio = page_folio(page); 202 int retval; 203 204 p9_debug(P9_DEBUG_VFS, "folio %p\n", folio); 205 206 retval = v9fs_vfs_write_folio_locked(folio); 207 if (retval < 0) { 208 if (retval == -EAGAIN) { 209 folio_redirty_for_writepage(wbc, folio); 210 retval = 0; 211 } else { 212 mapping_set_error(folio_mapping(folio), retval); 213 } 214 } else 215 retval = 0; 216 217 folio_unlock(folio); 218 return retval; 219 } 220 221 static int v9fs_launder_folio(struct folio *folio) 222 { 223 int retval; 224 225 if (folio_clear_dirty_for_io(folio)) { 226 retval = v9fs_vfs_write_folio_locked(folio); 227 if (retval) 228 return retval; 229 } 230 folio_wait_fscache(folio); 231 return 0; 232 } 233 234 /** 235 * v9fs_direct_IO - 9P address space operation for direct I/O 236 * @iocb: target I/O control block 237 * @iter: The data/buffer to use 238 * 239 * The presence of v9fs_direct_IO() in the address space ops vector 240 * allowes open() O_DIRECT flags which would have failed otherwise. 241 * 242 * In the non-cached mode, we shunt off direct read and write requests before 243 * the VFS gets them, so this method should never be called. 244 * 245 * Direct IO is not 'yet' supported in the cached mode. Hence when 246 * this routine is called through generic_file_aio_read(), the read/write fails 247 * with an error. 248 * 249 */ 250 static ssize_t 251 v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 252 { 253 struct file *file = iocb->ki_filp; 254 loff_t pos = iocb->ki_pos; 255 ssize_t n; 256 int err = 0; 257 258 if (iov_iter_rw(iter) == WRITE) { 259 n = p9_client_write(file->private_data, pos, iter, &err); 260 if (n) { 261 struct inode *inode = file_inode(file); 262 loff_t i_size = i_size_read(inode); 263 264 if (pos + n > i_size) 265 inode_add_bytes(inode, pos + n - i_size); 266 } 267 } else { 268 n = p9_client_read(file->private_data, pos, iter, &err); 269 } 270 return n ? n : err; 271 } 272 273 static int v9fs_write_begin(struct file *filp, struct address_space *mapping, 274 loff_t pos, unsigned int len, 275 struct page **subpagep, void **fsdata) 276 { 277 int retval; 278 struct folio *folio; 279 struct v9fs_inode *v9inode = V9FS_I(mapping->host); 280 281 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 282 283 BUG_ON(!v9inode->writeback_fid); 284 285 /* Prefetch area to be written into the cache if we're caching this 286 * file. We need to do this before we get a lock on the page in case 287 * there's more than one writer competing for the same cache block. 288 */ 289 retval = netfs_write_begin(&v9inode->netfs, filp, mapping, pos, len, &folio, fsdata); 290 if (retval < 0) 291 return retval; 292 293 *subpagep = &folio->page; 294 return retval; 295 } 296 297 static int v9fs_write_end(struct file *filp, struct address_space *mapping, 298 loff_t pos, unsigned int len, unsigned int copied, 299 struct page *subpage, void *fsdata) 300 { 301 loff_t last_pos = pos + copied; 302 struct folio *folio = page_folio(subpage); 303 struct inode *inode = mapping->host; 304 struct v9fs_inode *v9inode = V9FS_I(inode); 305 306 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 307 308 if (!folio_test_uptodate(folio)) { 309 if (unlikely(copied < len)) { 310 copied = 0; 311 goto out; 312 } 313 314 folio_mark_uptodate(folio); 315 } 316 317 /* 318 * No need to use i_size_read() here, the i_size 319 * cannot change under us because we hold the i_mutex. 320 */ 321 if (last_pos > inode->i_size) { 322 inode_add_bytes(inode, last_pos - inode->i_size); 323 i_size_write(inode, last_pos); 324 fscache_update_cookie(v9fs_inode_cookie(v9inode), NULL, &last_pos); 325 } 326 folio_mark_dirty(folio); 327 out: 328 folio_unlock(folio); 329 folio_put(folio); 330 331 return copied; 332 } 333 334 #ifdef CONFIG_9P_FSCACHE 335 /* 336 * Mark a page as having been made dirty and thus needing writeback. We also 337 * need to pin the cache object to write back to. 338 */ 339 static bool v9fs_dirty_folio(struct address_space *mapping, struct folio *folio) 340 { 341 struct v9fs_inode *v9inode = V9FS_I(mapping->host); 342 343 return fscache_dirty_folio(mapping, folio, v9fs_inode_cookie(v9inode)); 344 } 345 #else 346 #define v9fs_dirty_folio filemap_dirty_folio 347 #endif 348 349 const struct address_space_operations v9fs_addr_operations = { 350 .read_folio = netfs_read_folio, 351 .readahead = netfs_readahead, 352 .dirty_folio = v9fs_dirty_folio, 353 .writepage = v9fs_vfs_writepage, 354 .write_begin = v9fs_write_begin, 355 .write_end = v9fs_write_end, 356 .release_folio = v9fs_release_folio, 357 .invalidate_folio = v9fs_invalidate_folio, 358 .launder_folio = v9fs_launder_folio, 359 .direct_IO = v9fs_direct_IO, 360 }; 361