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_req_cleanup - Cleanup request initialized by v9fs_init_request 70 * @mapping: unused mapping of request to cleanup 71 * @priv: private data to cleanup, a fid, guaranted non-null. 72 */ 73 static void v9fs_req_cleanup(struct address_space *mapping, void *priv) 74 { 75 struct p9_fid *fid = priv; 76 77 p9_client_clunk(fid); 78 } 79 80 /** 81 * v9fs_begin_cache_operation - Begin a cache operation for a read 82 * @rreq: The read request 83 */ 84 static int v9fs_begin_cache_operation(struct netfs_io_request *rreq) 85 { 86 #ifdef CONFIG_9P_FSCACHE 87 struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(rreq->inode)); 88 89 return fscache_begin_read_operation(&rreq->cache_resources, cookie); 90 #else 91 return -ENOBUFS; 92 #endif 93 } 94 95 const struct netfs_request_ops v9fs_req_ops = { 96 .init_request = v9fs_init_request, 97 .begin_cache_operation = v9fs_begin_cache_operation, 98 .issue_read = v9fs_issue_read, 99 .cleanup = v9fs_req_cleanup, 100 }; 101 102 /** 103 * v9fs_release_folio - release the private state associated with a folio 104 * @folio: The folio to be released 105 * @gfp: The caller's allocation restrictions 106 * 107 * Returns true if the page can be released, false otherwise. 108 */ 109 110 static bool v9fs_release_folio(struct folio *folio, gfp_t gfp) 111 { 112 struct inode *inode = folio_inode(folio); 113 114 if (folio_test_private(folio)) 115 return false; 116 #ifdef CONFIG_9P_FSCACHE 117 if (folio_test_fscache(folio)) { 118 if (current_is_kswapd() || !(gfp & __GFP_FS)) 119 return false; 120 folio_wait_fscache(folio); 121 } 122 #endif 123 fscache_note_page_release(v9fs_inode_cookie(V9FS_I(inode))); 124 return true; 125 } 126 127 static void v9fs_invalidate_folio(struct folio *folio, size_t offset, 128 size_t length) 129 { 130 folio_wait_fscache(folio); 131 } 132 133 static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error, 134 bool was_async) 135 { 136 struct v9fs_inode *v9inode = priv; 137 __le32 version; 138 139 if (IS_ERR_VALUE(transferred_or_error) && 140 transferred_or_error != -ENOBUFS) { 141 version = cpu_to_le32(v9inode->qid.version); 142 fscache_invalidate(v9fs_inode_cookie(v9inode), &version, 143 i_size_read(&v9inode->vfs_inode), 0); 144 } 145 } 146 147 static int v9fs_vfs_write_folio_locked(struct folio *folio) 148 { 149 struct inode *inode = folio_inode(folio); 150 struct v9fs_inode *v9inode = V9FS_I(inode); 151 struct fscache_cookie *cookie = v9fs_inode_cookie(v9inode); 152 loff_t start = folio_pos(folio); 153 loff_t i_size = i_size_read(inode); 154 struct iov_iter from; 155 size_t len = folio_size(folio); 156 int err; 157 158 if (start >= i_size) 159 return 0; /* Simultaneous truncation occurred */ 160 161 len = min_t(loff_t, i_size - start, len); 162 163 iov_iter_xarray(&from, WRITE, &folio_mapping(folio)->i_pages, start, len); 164 165 /* We should have writeback_fid always set */ 166 BUG_ON(!v9inode->writeback_fid); 167 168 folio_wait_fscache(folio); 169 folio_start_writeback(folio); 170 171 p9_client_write(v9inode->writeback_fid, start, &from, &err); 172 173 if (err == 0 && 174 fscache_cookie_enabled(cookie) && 175 test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags)) { 176 folio_start_fscache(folio); 177 fscache_write_to_cache(v9fs_inode_cookie(v9inode), 178 folio_mapping(folio), start, len, i_size, 179 v9fs_write_to_cache_done, v9inode, 180 true); 181 } 182 183 folio_end_writeback(folio); 184 return err; 185 } 186 187 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) 188 { 189 struct folio *folio = page_folio(page); 190 int retval; 191 192 p9_debug(P9_DEBUG_VFS, "folio %p\n", folio); 193 194 retval = v9fs_vfs_write_folio_locked(folio); 195 if (retval < 0) { 196 if (retval == -EAGAIN) { 197 folio_redirty_for_writepage(wbc, folio); 198 retval = 0; 199 } else { 200 mapping_set_error(folio_mapping(folio), retval); 201 } 202 } else 203 retval = 0; 204 205 folio_unlock(folio); 206 return retval; 207 } 208 209 static int v9fs_launder_folio(struct folio *folio) 210 { 211 int retval; 212 213 if (folio_clear_dirty_for_io(folio)) { 214 retval = v9fs_vfs_write_folio_locked(folio); 215 if (retval) 216 return retval; 217 } 218 folio_wait_fscache(folio); 219 return 0; 220 } 221 222 /** 223 * v9fs_direct_IO - 9P address space operation for direct I/O 224 * @iocb: target I/O control block 225 * @iter: The data/buffer to use 226 * 227 * The presence of v9fs_direct_IO() in the address space ops vector 228 * allowes open() O_DIRECT flags which would have failed otherwise. 229 * 230 * In the non-cached mode, we shunt off direct read and write requests before 231 * the VFS gets them, so this method should never be called. 232 * 233 * Direct IO is not 'yet' supported in the cached mode. Hence when 234 * this routine is called through generic_file_aio_read(), the read/write fails 235 * with an error. 236 * 237 */ 238 static ssize_t 239 v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 240 { 241 struct file *file = iocb->ki_filp; 242 loff_t pos = iocb->ki_pos; 243 ssize_t n; 244 int err = 0; 245 246 if (iov_iter_rw(iter) == WRITE) { 247 n = p9_client_write(file->private_data, pos, iter, &err); 248 if (n) { 249 struct inode *inode = file_inode(file); 250 loff_t i_size = i_size_read(inode); 251 252 if (pos + n > i_size) 253 inode_add_bytes(inode, pos + n - i_size); 254 } 255 } else { 256 n = p9_client_read(file->private_data, pos, iter, &err); 257 } 258 return n ? n : err; 259 } 260 261 static int v9fs_write_begin(struct file *filp, struct address_space *mapping, 262 loff_t pos, unsigned int len, 263 struct page **subpagep, void **fsdata) 264 { 265 int retval; 266 struct folio *folio; 267 struct v9fs_inode *v9inode = V9FS_I(mapping->host); 268 269 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 270 271 BUG_ON(!v9inode->writeback_fid); 272 273 /* Prefetch area to be written into the cache if we're caching this 274 * file. We need to do this before we get a lock on the page in case 275 * there's more than one writer competing for the same cache block. 276 */ 277 retval = netfs_write_begin(filp, mapping, pos, len, &folio, fsdata); 278 if (retval < 0) 279 return retval; 280 281 *subpagep = &folio->page; 282 return retval; 283 } 284 285 static int v9fs_write_end(struct file *filp, struct address_space *mapping, 286 loff_t pos, unsigned int len, unsigned int copied, 287 struct page *subpage, void *fsdata) 288 { 289 loff_t last_pos = pos + copied; 290 struct folio *folio = page_folio(subpage); 291 struct inode *inode = mapping->host; 292 struct v9fs_inode *v9inode = V9FS_I(inode); 293 294 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 295 296 if (!folio_test_uptodate(folio)) { 297 if (unlikely(copied < len)) { 298 copied = 0; 299 goto out; 300 } 301 302 folio_mark_uptodate(folio); 303 } 304 305 /* 306 * No need to use i_size_read() here, the i_size 307 * cannot change under us because we hold the i_mutex. 308 */ 309 if (last_pos > inode->i_size) { 310 inode_add_bytes(inode, last_pos - inode->i_size); 311 i_size_write(inode, last_pos); 312 fscache_update_cookie(v9fs_inode_cookie(v9inode), NULL, &last_pos); 313 } 314 folio_mark_dirty(folio); 315 out: 316 folio_unlock(folio); 317 folio_put(folio); 318 319 return copied; 320 } 321 322 #ifdef CONFIG_9P_FSCACHE 323 /* 324 * Mark a page as having been made dirty and thus needing writeback. We also 325 * need to pin the cache object to write back to. 326 */ 327 static bool v9fs_dirty_folio(struct address_space *mapping, struct folio *folio) 328 { 329 struct v9fs_inode *v9inode = V9FS_I(mapping->host); 330 331 return fscache_dirty_folio(mapping, folio, v9fs_inode_cookie(v9inode)); 332 } 333 #else 334 #define v9fs_dirty_folio filemap_dirty_folio 335 #endif 336 337 const struct address_space_operations v9fs_addr_operations = { 338 .read_folio = netfs_read_folio, 339 .readahead = netfs_readahead, 340 .dirty_folio = v9fs_dirty_folio, 341 .writepage = v9fs_vfs_writepage, 342 .write_begin = v9fs_write_begin, 343 .write_end = v9fs_write_end, 344 .release_folio = v9fs_release_folio, 345 .invalidate_folio = v9fs_invalidate_folio, 346 .launder_folio = v9fs_launder_folio, 347 .direct_IO = v9fs_direct_IO, 348 }; 349