| 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 <net/9p/9p.h> |
| 38 | #include <net/9p/client.h> |
| 39 | |
| 40 | #include "v9fs.h" |
| 41 | #include "v9fs_vfs.h" |
| 42 | #include "cache.h" |
| 43 | #include "fid.h" |
| 44 | |
| 45 | /** |
| 46 | * v9fs_fid_readpage - read an entire page in from 9P |
| 47 | * |
| 48 | * @fid: fid being read |
| 49 | * @page: structure to page |
| 50 | * |
| 51 | */ |
| 52 | static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page) |
| 53 | { |
| 54 | struct inode *inode = page->mapping->host; |
| 55 | struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE}; |
| 56 | struct iov_iter to; |
| 57 | int retval, err; |
| 58 | |
| 59 | p9_debug(P9_DEBUG_VFS, "\n"); |
| 60 | |
| 61 | BUG_ON(!PageLocked(page)); |
| 62 | |
| 63 | retval = v9fs_readpage_from_fscache(inode, page); |
| 64 | if (retval == 0) |
| 65 | return retval; |
| 66 | |
| 67 | iov_iter_bvec(&to, ITER_BVEC | READ, &bvec, 1, PAGE_SIZE); |
| 68 | |
| 69 | retval = p9_client_read(fid, page_offset(page), &to, &err); |
| 70 | if (err) { |
| 71 | v9fs_uncache_page(inode, page); |
| 72 | retval = err; |
| 73 | goto done; |
| 74 | } |
| 75 | |
| 76 | zero_user(page, retval, PAGE_SIZE - retval); |
| 77 | flush_dcache_page(page); |
| 78 | SetPageUptodate(page); |
| 79 | |
| 80 | v9fs_readpage_to_fscache(inode, page); |
| 81 | retval = 0; |
| 82 | |
| 83 | done: |
| 84 | unlock_page(page); |
| 85 | return retval; |
| 86 | } |
| 87 | |
| 88 | /** |
| 89 | * v9fs_vfs_readpage - read an entire page in from 9P |
| 90 | * |
| 91 | * @filp: file being read |
| 92 | * @page: structure to page |
| 93 | * |
| 94 | */ |
| 95 | |
| 96 | static int v9fs_vfs_readpage(struct file *filp, struct page *page) |
| 97 | { |
| 98 | return v9fs_fid_readpage(filp->private_data, page); |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * v9fs_vfs_readpages - read a set of pages from 9P |
| 103 | * |
| 104 | * @filp: file being read |
| 105 | * @mapping: the address space |
| 106 | * @pages: list of pages to read |
| 107 | * @nr_pages: count of pages to read |
| 108 | * |
| 109 | */ |
| 110 | |
| 111 | static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping, |
| 112 | struct list_head *pages, unsigned nr_pages) |
| 113 | { |
| 114 | int ret = 0; |
| 115 | struct inode *inode; |
| 116 | |
| 117 | inode = mapping->host; |
| 118 | p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp); |
| 119 | |
| 120 | ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages); |
| 121 | if (ret == 0) |
| 122 | return ret; |
| 123 | |
| 124 | ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp); |
| 125 | p9_debug(P9_DEBUG_VFS, " = %d\n", ret); |
| 126 | return ret; |
| 127 | } |
| 128 | |
| 129 | /** |
| 130 | * v9fs_release_page - release the private state associated with a page |
| 131 | * |
| 132 | * Returns 1 if the page can be released, false otherwise. |
| 133 | */ |
| 134 | |
| 135 | static int v9fs_release_page(struct page *page, gfp_t gfp) |
| 136 | { |
| 137 | if (PagePrivate(page)) |
| 138 | return 0; |
| 139 | return v9fs_fscache_release_page(page, gfp); |
| 140 | } |
| 141 | |
| 142 | /** |
| 143 | * v9fs_invalidate_page - Invalidate a page completely or partially |
| 144 | * |
| 145 | * @page: structure to page |
| 146 | * @offset: offset in the page |
| 147 | */ |
| 148 | |
| 149 | static void v9fs_invalidate_page(struct page *page, unsigned int offset, |
| 150 | unsigned int length) |
| 151 | { |
| 152 | /* |
| 153 | * If called with zero offset, we should release |
| 154 | * the private state assocated with the page |
| 155 | */ |
| 156 | if (offset == 0 && length == PAGE_CACHE_SIZE) |
| 157 | v9fs_fscache_invalidate_page(page); |
| 158 | } |
| 159 | |
| 160 | static int v9fs_vfs_writepage_locked(struct page *page) |
| 161 | { |
| 162 | struct inode *inode = page->mapping->host; |
| 163 | struct v9fs_inode *v9inode = V9FS_I(inode); |
| 164 | loff_t size = i_size_read(inode); |
| 165 | struct iov_iter from; |
| 166 | struct bio_vec bvec; |
| 167 | int err, len; |
| 168 | |
| 169 | if (page->index == size >> PAGE_CACHE_SHIFT) |
| 170 | len = size & ~PAGE_CACHE_MASK; |
| 171 | else |
| 172 | len = PAGE_CACHE_SIZE; |
| 173 | |
| 174 | bvec.bv_page = page; |
| 175 | bvec.bv_offset = 0; |
| 176 | bvec.bv_len = len; |
| 177 | iov_iter_bvec(&from, ITER_BVEC | WRITE, &bvec, 1, len); |
| 178 | |
| 179 | /* We should have writeback_fid always set */ |
| 180 | BUG_ON(!v9inode->writeback_fid); |
| 181 | |
| 182 | set_page_writeback(page); |
| 183 | |
| 184 | p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err); |
| 185 | |
| 186 | end_page_writeback(page); |
| 187 | return err; |
| 188 | } |
| 189 | |
| 190 | static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) |
| 191 | { |
| 192 | int retval; |
| 193 | |
| 194 | p9_debug(P9_DEBUG_VFS, "page %p\n", page); |
| 195 | |
| 196 | retval = v9fs_vfs_writepage_locked(page); |
| 197 | if (retval < 0) { |
| 198 | if (retval == -EAGAIN) { |
| 199 | redirty_page_for_writepage(wbc, page); |
| 200 | retval = 0; |
| 201 | } else { |
| 202 | SetPageError(page); |
| 203 | mapping_set_error(page->mapping, retval); |
| 204 | } |
| 205 | } else |
| 206 | retval = 0; |
| 207 | |
| 208 | unlock_page(page); |
| 209 | return retval; |
| 210 | } |
| 211 | |
| 212 | /** |
| 213 | * v9fs_launder_page - Writeback a dirty page |
| 214 | * Returns 0 on success. |
| 215 | */ |
| 216 | |
| 217 | static int v9fs_launder_page(struct page *page) |
| 218 | { |
| 219 | int retval; |
| 220 | struct inode *inode = page->mapping->host; |
| 221 | |
| 222 | v9fs_fscache_wait_on_page_write(inode, page); |
| 223 | if (clear_page_dirty_for_io(page)) { |
| 224 | retval = v9fs_vfs_writepage_locked(page); |
| 225 | if (retval) |
| 226 | return retval; |
| 227 | } |
| 228 | return 0; |
| 229 | } |
| 230 | |
| 231 | /** |
| 232 | * v9fs_direct_IO - 9P address space operation for direct I/O |
| 233 | * @iocb: target I/O control block |
| 234 | * @pos: offset in file to begin the operation |
| 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, loff_t pos) |
| 249 | { |
| 250 | struct file *file = iocb->ki_filp; |
| 251 | ssize_t n; |
| 252 | int err = 0; |
| 253 | if (iov_iter_rw(iter) == WRITE) { |
| 254 | n = p9_client_write(file->private_data, pos, iter, &err); |
| 255 | if (n) { |
| 256 | struct inode *inode = file_inode(file); |
| 257 | loff_t i_size = i_size_read(inode); |
| 258 | if (pos + n > i_size) |
| 259 | inode_add_bytes(inode, pos + n - i_size); |
| 260 | } |
| 261 | } else { |
| 262 | n = p9_client_read(file->private_data, pos, iter, &err); |
| 263 | } |
| 264 | return n ? n : err; |
| 265 | } |
| 266 | |
| 267 | static int v9fs_write_begin(struct file *filp, struct address_space *mapping, |
| 268 | loff_t pos, unsigned len, unsigned flags, |
| 269 | struct page **pagep, void **fsdata) |
| 270 | { |
| 271 | int retval = 0; |
| 272 | struct page *page; |
| 273 | struct v9fs_inode *v9inode; |
| 274 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; |
| 275 | struct inode *inode = mapping->host; |
| 276 | |
| 277 | |
| 278 | p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); |
| 279 | |
| 280 | v9inode = V9FS_I(inode); |
| 281 | start: |
| 282 | page = grab_cache_page_write_begin(mapping, index, flags); |
| 283 | if (!page) { |
| 284 | retval = -ENOMEM; |
| 285 | goto out; |
| 286 | } |
| 287 | BUG_ON(!v9inode->writeback_fid); |
| 288 | if (PageUptodate(page)) |
| 289 | goto out; |
| 290 | |
| 291 | if (len == PAGE_CACHE_SIZE) |
| 292 | goto out; |
| 293 | |
| 294 | retval = v9fs_fid_readpage(v9inode->writeback_fid, page); |
| 295 | page_cache_release(page); |
| 296 | if (!retval) |
| 297 | goto start; |
| 298 | out: |
| 299 | *pagep = page; |
| 300 | return retval; |
| 301 | } |
| 302 | |
| 303 | static int v9fs_write_end(struct file *filp, struct address_space *mapping, |
| 304 | loff_t pos, unsigned len, unsigned copied, |
| 305 | struct page *page, void *fsdata) |
| 306 | { |
| 307 | loff_t last_pos = pos + copied; |
| 308 | struct inode *inode = page->mapping->host; |
| 309 | |
| 310 | p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); |
| 311 | |
| 312 | if (unlikely(copied < len)) { |
| 313 | /* |
| 314 | * zero out the rest of the area |
| 315 | */ |
| 316 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
| 317 | |
| 318 | zero_user(page, from + copied, len - copied); |
| 319 | flush_dcache_page(page); |
| 320 | } |
| 321 | |
| 322 | if (!PageUptodate(page)) |
| 323 | SetPageUptodate(page); |
| 324 | /* |
| 325 | * No need to use i_size_read() here, the i_size |
| 326 | * cannot change under us because we hold the i_mutex. |
| 327 | */ |
| 328 | if (last_pos > inode->i_size) { |
| 329 | inode_add_bytes(inode, last_pos - inode->i_size); |
| 330 | i_size_write(inode, last_pos); |
| 331 | } |
| 332 | set_page_dirty(page); |
| 333 | unlock_page(page); |
| 334 | page_cache_release(page); |
| 335 | |
| 336 | return copied; |
| 337 | } |
| 338 | |
| 339 | |
| 340 | const struct address_space_operations v9fs_addr_operations = { |
| 341 | .readpage = v9fs_vfs_readpage, |
| 342 | .readpages = v9fs_vfs_readpages, |
| 343 | .set_page_dirty = __set_page_dirty_nobuffers, |
| 344 | .writepage = v9fs_vfs_writepage, |
| 345 | .write_begin = v9fs_write_begin, |
| 346 | .write_end = v9fs_write_end, |
| 347 | .releasepage = v9fs_release_page, |
| 348 | .invalidatepage = v9fs_invalidate_page, |
| 349 | .launder_page = v9fs_launder_page, |
| 350 | .direct_IO = v9fs_direct_IO, |
| 351 | }; |