1 /* 2 * linux/fs/9p/vfs_addr.c 3 * 4 * This file contians vfs address (mmap) ops for 9P2000. 5 * 6 * Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com> 7 * Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 11 * as published by the Free Software Foundation. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to: 20 * Free Software Foundation 21 * 51 Franklin Street, Fifth Floor 22 * Boston, MA 02111-1301 USA 23 * 24 */ 25 26 #include <linux/module.h> 27 #include <linux/errno.h> 28 #include <linux/fs.h> 29 #include <linux/file.h> 30 #include <linux/stat.h> 31 #include <linux/string.h> 32 #include <linux/inet.h> 33 #include <linux/pagemap.h> 34 #include <linux/idr.h> 35 #include <linux/sched.h> 36 #include <linux/uio.h> 37 #include <linux/bvec.h> 38 #include <net/9p/9p.h> 39 #include <net/9p/client.h> 40 41 #include "v9fs.h" 42 #include "v9fs_vfs.h" 43 #include "cache.h" 44 #include "fid.h" 45 46 /** 47 * v9fs_fid_readpage - read an entire page in from 9P 48 * 49 * @fid: fid being read 50 * @page: structure to page 51 * 52 */ 53 static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page) 54 { 55 struct inode *inode = page->mapping->host; 56 struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE}; 57 struct iov_iter to; 58 int retval, err; 59 60 p9_debug(P9_DEBUG_VFS, "\n"); 61 62 BUG_ON(!PageLocked(page)); 63 64 retval = v9fs_readpage_from_fscache(inode, page); 65 if (retval == 0) 66 return retval; 67 68 iov_iter_bvec(&to, ITER_BVEC | READ, &bvec, 1, PAGE_SIZE); 69 70 retval = p9_client_read(fid, page_offset(page), &to, &err); 71 if (err) { 72 v9fs_uncache_page(inode, page); 73 retval = err; 74 goto done; 75 } 76 77 zero_user(page, retval, PAGE_SIZE - retval); 78 flush_dcache_page(page); 79 SetPageUptodate(page); 80 81 v9fs_readpage_to_fscache(inode, page); 82 retval = 0; 83 84 done: 85 unlock_page(page); 86 return retval; 87 } 88 89 /** 90 * v9fs_vfs_readpage - read an entire page in from 9P 91 * 92 * @filp: file being read 93 * @page: structure to page 94 * 95 */ 96 97 static int v9fs_vfs_readpage(struct file *filp, struct page *page) 98 { 99 return v9fs_fid_readpage(filp->private_data, page); 100 } 101 102 /** 103 * v9fs_vfs_readpages - read a set of pages from 9P 104 * 105 * @filp: file being read 106 * @mapping: the address space 107 * @pages: list of pages to read 108 * @nr_pages: count of pages to read 109 * 110 */ 111 112 static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping, 113 struct list_head *pages, unsigned nr_pages) 114 { 115 int ret = 0; 116 struct inode *inode; 117 118 inode = mapping->host; 119 p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp); 120 121 ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages); 122 if (ret == 0) 123 return ret; 124 125 ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp); 126 p9_debug(P9_DEBUG_VFS, " = %d\n", ret); 127 return ret; 128 } 129 130 /** 131 * v9fs_release_page - release the private state associated with a page 132 * 133 * Returns 1 if the page can be released, false otherwise. 134 */ 135 136 static int v9fs_release_page(struct page *page, gfp_t gfp) 137 { 138 if (PagePrivate(page)) 139 return 0; 140 return v9fs_fscache_release_page(page, gfp); 141 } 142 143 /** 144 * v9fs_invalidate_page - Invalidate a page completely or partially 145 * 146 * @page: structure to page 147 * @offset: offset in the page 148 */ 149 150 static void v9fs_invalidate_page(struct page *page, unsigned int offset, 151 unsigned int length) 152 { 153 /* 154 * If called with zero offset, we should release 155 * the private state assocated with the page 156 */ 157 if (offset == 0 && length == PAGE_SIZE) 158 v9fs_fscache_invalidate_page(page); 159 } 160 161 static int v9fs_vfs_writepage_locked(struct page *page) 162 { 163 struct inode *inode = page->mapping->host; 164 struct v9fs_inode *v9inode = V9FS_I(inode); 165 loff_t size = i_size_read(inode); 166 struct iov_iter from; 167 struct bio_vec bvec; 168 int err, len; 169 170 if (page->index == size >> PAGE_SHIFT) 171 len = size & ~PAGE_MASK; 172 else 173 len = PAGE_SIZE; 174 175 bvec.bv_page = page; 176 bvec.bv_offset = 0; 177 bvec.bv_len = len; 178 iov_iter_bvec(&from, ITER_BVEC | WRITE, &bvec, 1, len); 179 180 /* We should have writeback_fid always set */ 181 BUG_ON(!v9inode->writeback_fid); 182 183 set_page_writeback(page); 184 185 p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err); 186 187 end_page_writeback(page); 188 return err; 189 } 190 191 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) 192 { 193 int retval; 194 195 p9_debug(P9_DEBUG_VFS, "page %p\n", page); 196 197 retval = v9fs_vfs_writepage_locked(page); 198 if (retval < 0) { 199 if (retval == -EAGAIN) { 200 redirty_page_for_writepage(wbc, page); 201 retval = 0; 202 } else { 203 SetPageError(page); 204 mapping_set_error(page->mapping, retval); 205 } 206 } else 207 retval = 0; 208 209 unlock_page(page); 210 return retval; 211 } 212 213 /** 214 * v9fs_launder_page - Writeback a dirty page 215 * Returns 0 on success. 216 */ 217 218 static int v9fs_launder_page(struct page *page) 219 { 220 int retval; 221 struct inode *inode = page->mapping->host; 222 223 v9fs_fscache_wait_on_page_write(inode, page); 224 if (clear_page_dirty_for_io(page)) { 225 retval = v9fs_vfs_writepage_locked(page); 226 if (retval) 227 return retval; 228 } 229 return 0; 230 } 231 232 /** 233 * v9fs_direct_IO - 9P address space operation for direct I/O 234 * @iocb: target I/O control block 235 * 236 * The presence of v9fs_direct_IO() in the address space ops vector 237 * allowes open() O_DIRECT flags which would have failed otherwise. 238 * 239 * In the non-cached mode, we shunt off direct read and write requests before 240 * the VFS gets them, so this method should never be called. 241 * 242 * Direct IO is not 'yet' supported in the cached mode. Hence when 243 * this routine is called through generic_file_aio_read(), the read/write fails 244 * with an error. 245 * 246 */ 247 static ssize_t 248 v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 249 { 250 struct file *file = iocb->ki_filp; 251 loff_t pos = iocb->ki_pos; 252 ssize_t n; 253 int err = 0; 254 if (iov_iter_rw(iter) == WRITE) { 255 n = p9_client_write(file->private_data, pos, iter, &err); 256 if (n) { 257 struct inode *inode = file_inode(file); 258 loff_t i_size = i_size_read(inode); 259 if (pos + n > i_size) 260 inode_add_bytes(inode, pos + n - i_size); 261 } 262 } else { 263 n = p9_client_read(file->private_data, pos, iter, &err); 264 } 265 return n ? n : err; 266 } 267 268 static int v9fs_write_begin(struct file *filp, struct address_space *mapping, 269 loff_t pos, unsigned len, unsigned flags, 270 struct page **pagep, void **fsdata) 271 { 272 int retval = 0; 273 struct page *page; 274 struct v9fs_inode *v9inode; 275 pgoff_t index = pos >> PAGE_SHIFT; 276 struct inode *inode = mapping->host; 277 278 279 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 280 281 v9inode = V9FS_I(inode); 282 start: 283 page = grab_cache_page_write_begin(mapping, index, flags); 284 if (!page) { 285 retval = -ENOMEM; 286 goto out; 287 } 288 BUG_ON(!v9inode->writeback_fid); 289 if (PageUptodate(page)) 290 goto out; 291 292 if (len == PAGE_SIZE) 293 goto out; 294 295 retval = v9fs_fid_readpage(v9inode->writeback_fid, page); 296 put_page(page); 297 if (!retval) 298 goto start; 299 out: 300 *pagep = page; 301 return retval; 302 } 303 304 static int v9fs_write_end(struct file *filp, struct address_space *mapping, 305 loff_t pos, unsigned len, unsigned copied, 306 struct page *page, void *fsdata) 307 { 308 loff_t last_pos = pos + copied; 309 struct inode *inode = page->mapping->host; 310 311 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 312 313 if (!PageUptodate(page)) { 314 if (unlikely(copied < len)) { 315 copied = 0; 316 goto out; 317 } else if (len == PAGE_SIZE) { 318 SetPageUptodate(page); 319 } 320 } 321 /* 322 * No need to use i_size_read() here, the i_size 323 * cannot change under us because we hold the i_mutex. 324 */ 325 if (last_pos > inode->i_size) { 326 inode_add_bytes(inode, last_pos - inode->i_size); 327 i_size_write(inode, last_pos); 328 } 329 set_page_dirty(page); 330 out: 331 unlock_page(page); 332 put_page(page); 333 334 return copied; 335 } 336 337 338 const struct address_space_operations v9fs_addr_operations = { 339 .readpage = v9fs_vfs_readpage, 340 .readpages = v9fs_vfs_readpages, 341 .set_page_dirty = __set_page_dirty_nobuffers, 342 .writepage = v9fs_vfs_writepage, 343 .write_begin = v9fs_write_begin, 344 .write_end = v9fs_write_end, 345 .releasepage = v9fs_release_page, 346 .invalidatepage = v9fs_invalidate_page, 347 .launder_page = v9fs_launder_page, 348 .direct_IO = v9fs_direct_IO, 349 }; 350