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/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_req_issue_op - Issue a read from 9P 31 * @subreq: The read to make 32 */ 33 static void v9fs_req_issue_op(struct netfs_read_subrequest *subreq) 34 { 35 struct netfs_read_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, READ, &rreq->mapping->i_pages, pos, len); 43 44 total = p9_client_read(fid, pos, &to, &err); 45 netfs_subreq_terminated(subreq, err ?: total, false); 46 } 47 48 /** 49 * v9fs_init_rreq - Initialise a read request 50 * @rreq: The read request 51 * @file: The file being read from 52 */ 53 static void v9fs_init_rreq(struct netfs_read_request *rreq, struct file *file) 54 { 55 struct p9_fid *fid = file->private_data; 56 57 refcount_inc(&fid->count); 58 rreq->netfs_priv = fid; 59 } 60 61 /** 62 * v9fs_req_cleanup - Cleanup request initialized by v9fs_init_rreq 63 * @mapping: unused mapping of request to cleanup 64 * @priv: private data to cleanup, a fid, guaranted non-null. 65 */ 66 static void v9fs_req_cleanup(struct address_space *mapping, void *priv) 67 { 68 struct p9_fid *fid = priv; 69 70 p9_client_clunk(fid); 71 } 72 73 /** 74 * v9fs_is_cache_enabled - Determine if caching is enabled for an inode 75 * @inode: The inode to check 76 */ 77 static bool v9fs_is_cache_enabled(struct inode *inode) 78 { 79 struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(inode)); 80 81 return fscache_cookie_enabled(cookie) && !hlist_empty(&cookie->backing_objects); 82 } 83 84 /** 85 * v9fs_begin_cache_operation - Begin a cache operation for a read 86 * @rreq: The read request 87 */ 88 static int v9fs_begin_cache_operation(struct netfs_read_request *rreq) 89 { 90 struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(rreq->inode)); 91 92 return fscache_begin_read_operation(rreq, cookie); 93 } 94 95 static const struct netfs_read_request_ops v9fs_req_ops = { 96 .init_rreq = v9fs_init_rreq, 97 .is_cache_enabled = v9fs_is_cache_enabled, 98 .begin_cache_operation = v9fs_begin_cache_operation, 99 .issue_op = v9fs_req_issue_op, 100 .cleanup = v9fs_req_cleanup, 101 }; 102 103 /** 104 * v9fs_vfs_readpage - read an entire page in from 9P 105 * @file: file being read 106 * @page: structure to page 107 * 108 */ 109 static int v9fs_vfs_readpage(struct file *file, struct page *page) 110 { 111 return netfs_readpage(file, page, &v9fs_req_ops, NULL); 112 } 113 114 /** 115 * v9fs_vfs_readahead - read a set of pages from 9P 116 * @ractl: The readahead parameters 117 */ 118 static void v9fs_vfs_readahead(struct readahead_control *ractl) 119 { 120 netfs_readahead(ractl, &v9fs_req_ops, NULL); 121 } 122 123 /** 124 * v9fs_release_page - release the private state associated with a page 125 * @page: The page to be released 126 * @gfp: The caller's allocation restrictions 127 * 128 * Returns 1 if the page can be released, false otherwise. 129 */ 130 131 static int v9fs_release_page(struct page *page, gfp_t gfp) 132 { 133 if (PagePrivate(page)) 134 return 0; 135 #ifdef CONFIG_9P_FSCACHE 136 if (PageFsCache(page)) { 137 if (!(gfp & __GFP_DIRECT_RECLAIM) || !(gfp & __GFP_FS)) 138 return 0; 139 wait_on_page_fscache(page); 140 } 141 #endif 142 return 1; 143 } 144 145 /** 146 * v9fs_invalidate_page - Invalidate a page completely or partially 147 * @page: The page to be invalidated 148 * @offset: offset of the invalidated region 149 * @length: length of the invalidated region 150 */ 151 152 static void v9fs_invalidate_page(struct page *page, unsigned int offset, 153 unsigned int length) 154 { 155 wait_on_page_fscache(page); 156 } 157 158 static int v9fs_vfs_writepage_locked(struct page *page) 159 { 160 struct inode *inode = page->mapping->host; 161 struct v9fs_inode *v9inode = V9FS_I(inode); 162 loff_t start = page_offset(page); 163 loff_t size = i_size_read(inode); 164 struct iov_iter from; 165 int err, len; 166 167 if (page->index == size >> PAGE_SHIFT) 168 len = size & ~PAGE_MASK; 169 else 170 len = PAGE_SIZE; 171 172 iov_iter_xarray(&from, WRITE, &page->mapping->i_pages, start, len); 173 174 /* We should have writeback_fid always set */ 175 BUG_ON(!v9inode->writeback_fid); 176 177 set_page_writeback(page); 178 179 p9_client_write(v9inode->writeback_fid, start, &from, &err); 180 181 end_page_writeback(page); 182 return err; 183 } 184 185 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) 186 { 187 int retval; 188 189 p9_debug(P9_DEBUG_VFS, "page %p\n", page); 190 191 retval = v9fs_vfs_writepage_locked(page); 192 if (retval < 0) { 193 if (retval == -EAGAIN) { 194 redirty_page_for_writepage(wbc, page); 195 retval = 0; 196 } else { 197 SetPageError(page); 198 mapping_set_error(page->mapping, retval); 199 } 200 } else 201 retval = 0; 202 203 unlock_page(page); 204 return retval; 205 } 206 207 /** 208 * v9fs_launder_page - Writeback a dirty page 209 * @page: The page to be cleaned up 210 * 211 * Returns 0 on success. 212 */ 213 214 static int v9fs_launder_page(struct page *page) 215 { 216 int retval; 217 218 if (clear_page_dirty_for_io(page)) { 219 retval = v9fs_vfs_writepage_locked(page); 220 if (retval) 221 return retval; 222 } 223 wait_on_page_fscache(page); 224 return 0; 225 } 226 227 /** 228 * v9fs_direct_IO - 9P address space operation for direct I/O 229 * @iocb: target I/O control block 230 * @iter: The data/buffer to use 231 * 232 * The presence of v9fs_direct_IO() in the address space ops vector 233 * allowes open() O_DIRECT flags which would have failed otherwise. 234 * 235 * In the non-cached mode, we shunt off direct read and write requests before 236 * the VFS gets them, so this method should never be called. 237 * 238 * Direct IO is not 'yet' supported in the cached mode. Hence when 239 * this routine is called through generic_file_aio_read(), the read/write fails 240 * with an error. 241 * 242 */ 243 static ssize_t 244 v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 245 { 246 struct file *file = iocb->ki_filp; 247 loff_t pos = iocb->ki_pos; 248 ssize_t n; 249 int err = 0; 250 251 if (iov_iter_rw(iter) == WRITE) { 252 n = p9_client_write(file->private_data, pos, iter, &err); 253 if (n) { 254 struct inode *inode = file_inode(file); 255 loff_t i_size = i_size_read(inode); 256 257 if (pos + n > i_size) 258 inode_add_bytes(inode, pos + n - i_size); 259 } 260 } else { 261 n = p9_client_read(file->private_data, pos, iter, &err); 262 } 263 return n ? n : err; 264 } 265 266 static int v9fs_write_begin(struct file *filp, struct address_space *mapping, 267 loff_t pos, unsigned int len, unsigned int flags, 268 struct page **pagep, void **fsdata) 269 { 270 int retval; 271 struct page *page; 272 struct v9fs_inode *v9inode = V9FS_I(mapping->host); 273 274 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 275 276 BUG_ON(!v9inode->writeback_fid); 277 278 /* Prefetch area to be written into the cache if we're caching this 279 * file. We need to do this before we get a lock on the page in case 280 * there's more than one writer competing for the same cache block. 281 */ 282 retval = netfs_write_begin(filp, mapping, pos, len, flags, &page, fsdata, 283 &v9fs_req_ops, NULL); 284 if (retval < 0) 285 return retval; 286 287 *pagep = find_subpage(page, pos / PAGE_SIZE); 288 return retval; 289 } 290 291 static int v9fs_write_end(struct file *filp, struct address_space *mapping, 292 loff_t pos, unsigned int len, unsigned int copied, 293 struct page *page, void *fsdata) 294 { 295 loff_t last_pos = pos + copied; 296 struct inode *inode = page->mapping->host; 297 298 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 299 300 if (!PageUptodate(page)) { 301 if (unlikely(copied < len)) { 302 copied = 0; 303 goto out; 304 } 305 306 SetPageUptodate(page); 307 } 308 309 /* 310 * No need to use i_size_read() here, the i_size 311 * cannot change under us because we hold the i_mutex. 312 */ 313 if (last_pos > inode->i_size) { 314 inode_add_bytes(inode, last_pos - inode->i_size); 315 i_size_write(inode, last_pos); 316 } 317 set_page_dirty(page); 318 out: 319 unlock_page(page); 320 put_page(page); 321 322 return copied; 323 } 324 325 326 const struct address_space_operations v9fs_addr_operations = { 327 .readpage = v9fs_vfs_readpage, 328 .readahead = v9fs_vfs_readahead, 329 .set_page_dirty = __set_page_dirty_nobuffers, 330 .writepage = v9fs_vfs_writepage, 331 .write_begin = v9fs_write_begin, 332 .write_end = v9fs_write_end, 333 .releasepage = v9fs_release_page, 334 .invalidatepage = v9fs_invalidate_page, 335 .launder_page = v9fs_launder_page, 336 .direct_IO = v9fs_direct_IO, 337 }; 338