1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/fs/9p/vfs_addr.c 4 * 5 * This file contians vfs address (mmap) ops for 9P2000. 6 * 7 * Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com> 8 * Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov> 9 */ 10 11 #include <linux/module.h> 12 #include <linux/errno.h> 13 #include <linux/fs.h> 14 #include <linux/file.h> 15 #include <linux/stat.h> 16 #include <linux/string.h> 17 #include <linux/inet.h> 18 #include <linux/pagemap.h> 19 #include <linux/idr.h> 20 #include <linux/sched.h> 21 #include <linux/uio.h> 22 #include <linux/bvec.h> 23 #include <net/9p/9p.h> 24 #include <net/9p/client.h> 25 26 #include "v9fs.h" 27 #include "v9fs_vfs.h" 28 #include "cache.h" 29 #include "fid.h" 30 31 /** 32 * v9fs_fid_readpage - read an entire page in from 9P 33 * @data: Opaque pointer to the fid being read 34 * @page: structure to page 35 * 36 */ 37 static int v9fs_fid_readpage(void *data, struct page *page) 38 { 39 struct p9_fid *fid = data; 40 struct inode *inode = page->mapping->host; 41 struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE}; 42 struct iov_iter to; 43 int retval, err; 44 45 p9_debug(P9_DEBUG_VFS, "\n"); 46 47 BUG_ON(!PageLocked(page)); 48 49 retval = v9fs_readpage_from_fscache(inode, page); 50 if (retval == 0) 51 return retval; 52 53 iov_iter_bvec(&to, READ, &bvec, 1, PAGE_SIZE); 54 55 retval = p9_client_read(fid, page_offset(page), &to, &err); 56 if (err) { 57 v9fs_uncache_page(inode, page); 58 retval = err; 59 goto done; 60 } 61 62 zero_user(page, retval, PAGE_SIZE - retval); 63 flush_dcache_page(page); 64 SetPageUptodate(page); 65 66 v9fs_readpage_to_fscache(inode, page); 67 retval = 0; 68 69 done: 70 unlock_page(page); 71 return retval; 72 } 73 74 /** 75 * v9fs_vfs_readpage - read an entire page in from 9P 76 * 77 * @filp: file being read 78 * @page: structure to page 79 * 80 */ 81 82 static int v9fs_vfs_readpage(struct file *filp, struct page *page) 83 { 84 return v9fs_fid_readpage(filp->private_data, page); 85 } 86 87 /** 88 * v9fs_vfs_readpages - read a set of pages from 9P 89 * 90 * @filp: file being read 91 * @mapping: the address space 92 * @pages: list of pages to read 93 * @nr_pages: count of pages to read 94 * 95 */ 96 97 static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping, 98 struct list_head *pages, unsigned nr_pages) 99 { 100 int ret = 0; 101 struct inode *inode; 102 103 inode = mapping->host; 104 p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp); 105 106 ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages); 107 if (ret == 0) 108 return ret; 109 110 ret = read_cache_pages(mapping, pages, v9fs_fid_readpage, 111 filp->private_data); 112 p9_debug(P9_DEBUG_VFS, " = %d\n", ret); 113 return ret; 114 } 115 116 /** 117 * v9fs_release_page - release the private state associated with a page 118 * @page: The page to be released 119 * @gfp: The caller's allocation restrictions 120 * 121 * Returns 1 if the page can be released, false otherwise. 122 */ 123 124 static int v9fs_release_page(struct page *page, gfp_t gfp) 125 { 126 if (PagePrivate(page)) 127 return 0; 128 return v9fs_fscache_release_page(page, gfp); 129 } 130 131 /** 132 * v9fs_invalidate_page - Invalidate a page completely or partially 133 * @page: The page to be invalidated 134 * @offset: offset of the invalidated region 135 * @length: length of the invalidated region 136 */ 137 138 static void v9fs_invalidate_page(struct page *page, unsigned int offset, 139 unsigned int length) 140 { 141 /* 142 * If called with zero offset, we should release 143 * the private state assocated with the page 144 */ 145 if (offset == 0 && length == PAGE_SIZE) 146 v9fs_fscache_invalidate_page(page); 147 } 148 149 static int v9fs_vfs_writepage_locked(struct page *page) 150 { 151 struct inode *inode = page->mapping->host; 152 struct v9fs_inode *v9inode = V9FS_I(inode); 153 loff_t size = i_size_read(inode); 154 struct iov_iter from; 155 struct bio_vec bvec; 156 int err, len; 157 158 if (page->index == size >> PAGE_SHIFT) 159 len = size & ~PAGE_MASK; 160 else 161 len = PAGE_SIZE; 162 163 bvec.bv_page = page; 164 bvec.bv_offset = 0; 165 bvec.bv_len = len; 166 iov_iter_bvec(&from, WRITE, &bvec, 1, len); 167 168 /* We should have writeback_fid always set */ 169 BUG_ON(!v9inode->writeback_fid); 170 171 set_page_writeback(page); 172 173 p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err); 174 175 end_page_writeback(page); 176 return err; 177 } 178 179 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) 180 { 181 int retval; 182 183 p9_debug(P9_DEBUG_VFS, "page %p\n", page); 184 185 retval = v9fs_vfs_writepage_locked(page); 186 if (retval < 0) { 187 if (retval == -EAGAIN) { 188 redirty_page_for_writepage(wbc, page); 189 retval = 0; 190 } else { 191 SetPageError(page); 192 mapping_set_error(page->mapping, retval); 193 } 194 } else 195 retval = 0; 196 197 unlock_page(page); 198 return retval; 199 } 200 201 /** 202 * v9fs_launder_page - Writeback a dirty page 203 * @page: The page to be cleaned up 204 * 205 * Returns 0 on success. 206 */ 207 208 static int v9fs_launder_page(struct page *page) 209 { 210 int retval; 211 struct inode *inode = page->mapping->host; 212 213 v9fs_fscache_wait_on_page_write(inode, page); 214 if (clear_page_dirty_for_io(page)) { 215 retval = v9fs_vfs_writepage_locked(page); 216 if (retval) 217 return retval; 218 } 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 if (iov_iter_rw(iter) == WRITE) { 246 n = p9_client_write(file->private_data, pos, iter, &err); 247 if (n) { 248 struct inode *inode = file_inode(file); 249 loff_t i_size = i_size_read(inode); 250 if (pos + n > i_size) 251 inode_add_bytes(inode, pos + n - i_size); 252 } 253 } else { 254 n = p9_client_read(file->private_data, pos, iter, &err); 255 } 256 return n ? n : err; 257 } 258 259 static int v9fs_write_begin(struct file *filp, struct address_space *mapping, 260 loff_t pos, unsigned len, unsigned flags, 261 struct page **pagep, void **fsdata) 262 { 263 int retval = 0; 264 struct page *page; 265 struct v9fs_inode *v9inode; 266 pgoff_t index = pos >> PAGE_SHIFT; 267 struct inode *inode = mapping->host; 268 269 270 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 271 272 v9inode = V9FS_I(inode); 273 start: 274 page = grab_cache_page_write_begin(mapping, index, flags); 275 if (!page) { 276 retval = -ENOMEM; 277 goto out; 278 } 279 BUG_ON(!v9inode->writeback_fid); 280 if (PageUptodate(page)) 281 goto out; 282 283 if (len == PAGE_SIZE) 284 goto out; 285 286 retval = v9fs_fid_readpage(v9inode->writeback_fid, page); 287 put_page(page); 288 if (!retval) 289 goto start; 290 out: 291 *pagep = page; 292 return retval; 293 } 294 295 static int v9fs_write_end(struct file *filp, struct address_space *mapping, 296 loff_t pos, unsigned len, unsigned copied, 297 struct page *page, void *fsdata) 298 { 299 loff_t last_pos = pos + copied; 300 struct inode *inode = page->mapping->host; 301 302 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 303 304 if (!PageUptodate(page)) { 305 if (unlikely(copied < len)) { 306 copied = 0; 307 goto out; 308 } else if (len == PAGE_SIZE) { 309 SetPageUptodate(page); 310 } 311 } 312 /* 313 * No need to use i_size_read() here, the i_size 314 * cannot change under us because we hold the i_mutex. 315 */ 316 if (last_pos > inode->i_size) { 317 inode_add_bytes(inode, last_pos - inode->i_size); 318 i_size_write(inode, last_pos); 319 } 320 set_page_dirty(page); 321 out: 322 unlock_page(page); 323 put_page(page); 324 325 return copied; 326 } 327 328 329 const struct address_space_operations v9fs_addr_operations = { 330 .readpage = v9fs_vfs_readpage, 331 .readpages = v9fs_vfs_readpages, 332 .set_page_dirty = __set_page_dirty_nobuffers, 333 .writepage = v9fs_vfs_writepage, 334 .write_begin = v9fs_write_begin, 335 .write_end = v9fs_write_end, 336 .releasepage = v9fs_release_page, 337 .invalidatepage = v9fs_invalidate_page, 338 .launder_page = v9fs_launder_page, 339 .direct_IO = v9fs_direct_IO, 340 }; 341