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 * 34 * @fid: fid being read 35 * @page: structure to page 36 * 37 */ 38 static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page) 39 { 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, (void *)v9fs_vfs_readpage, filp); 111 p9_debug(P9_DEBUG_VFS, " = %d\n", ret); 112 return ret; 113 } 114 115 /** 116 * v9fs_release_page - release the private state associated with a page 117 * 118 * Returns 1 if the page can be released, false otherwise. 119 */ 120 121 static int v9fs_release_page(struct page *page, gfp_t gfp) 122 { 123 if (PagePrivate(page)) 124 return 0; 125 return v9fs_fscache_release_page(page, gfp); 126 } 127 128 /** 129 * v9fs_invalidate_page - Invalidate a page completely or partially 130 * 131 * @page: structure to page 132 * @offset: offset in the page 133 */ 134 135 static void v9fs_invalidate_page(struct page *page, unsigned int offset, 136 unsigned int length) 137 { 138 /* 139 * If called with zero offset, we should release 140 * the private state assocated with the page 141 */ 142 if (offset == 0 && length == PAGE_SIZE) 143 v9fs_fscache_invalidate_page(page); 144 } 145 146 static int v9fs_vfs_writepage_locked(struct page *page) 147 { 148 struct inode *inode = page->mapping->host; 149 struct v9fs_inode *v9inode = V9FS_I(inode); 150 loff_t size = i_size_read(inode); 151 struct iov_iter from; 152 struct bio_vec bvec; 153 int err, len; 154 155 if (page->index == size >> PAGE_SHIFT) 156 len = size & ~PAGE_MASK; 157 else 158 len = PAGE_SIZE; 159 160 bvec.bv_page = page; 161 bvec.bv_offset = 0; 162 bvec.bv_len = len; 163 iov_iter_bvec(&from, WRITE, &bvec, 1, len); 164 165 /* We should have writeback_fid always set */ 166 BUG_ON(!v9inode->writeback_fid); 167 168 set_page_writeback(page); 169 170 p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err); 171 172 end_page_writeback(page); 173 return err; 174 } 175 176 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) 177 { 178 int retval; 179 180 p9_debug(P9_DEBUG_VFS, "page %p\n", page); 181 182 retval = v9fs_vfs_writepage_locked(page); 183 if (retval < 0) { 184 if (retval == -EAGAIN) { 185 redirty_page_for_writepage(wbc, page); 186 retval = 0; 187 } else { 188 SetPageError(page); 189 mapping_set_error(page->mapping, retval); 190 } 191 } else 192 retval = 0; 193 194 unlock_page(page); 195 return retval; 196 } 197 198 /** 199 * v9fs_launder_page - Writeback a dirty page 200 * Returns 0 on success. 201 */ 202 203 static int v9fs_launder_page(struct page *page) 204 { 205 int retval; 206 struct inode *inode = page->mapping->host; 207 208 v9fs_fscache_wait_on_page_write(inode, page); 209 if (clear_page_dirty_for_io(page)) { 210 retval = v9fs_vfs_writepage_locked(page); 211 if (retval) 212 return retval; 213 } 214 return 0; 215 } 216 217 /** 218 * v9fs_direct_IO - 9P address space operation for direct I/O 219 * @iocb: target I/O control block 220 * 221 * The presence of v9fs_direct_IO() in the address space ops vector 222 * allowes open() O_DIRECT flags which would have failed otherwise. 223 * 224 * In the non-cached mode, we shunt off direct read and write requests before 225 * the VFS gets them, so this method should never be called. 226 * 227 * Direct IO is not 'yet' supported in the cached mode. Hence when 228 * this routine is called through generic_file_aio_read(), the read/write fails 229 * with an error. 230 * 231 */ 232 static ssize_t 233 v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 234 { 235 struct file *file = iocb->ki_filp; 236 loff_t pos = iocb->ki_pos; 237 ssize_t n; 238 int err = 0; 239 if (iov_iter_rw(iter) == WRITE) { 240 n = p9_client_write(file->private_data, pos, iter, &err); 241 if (n) { 242 struct inode *inode = file_inode(file); 243 loff_t i_size = i_size_read(inode); 244 if (pos + n > i_size) 245 inode_add_bytes(inode, pos + n - i_size); 246 } 247 } else { 248 n = p9_client_read(file->private_data, pos, iter, &err); 249 } 250 return n ? n : err; 251 } 252 253 static int v9fs_write_begin(struct file *filp, struct address_space *mapping, 254 loff_t pos, unsigned len, unsigned flags, 255 struct page **pagep, void **fsdata) 256 { 257 int retval = 0; 258 struct page *page; 259 struct v9fs_inode *v9inode; 260 pgoff_t index = pos >> PAGE_SHIFT; 261 struct inode *inode = mapping->host; 262 263 264 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 265 266 v9inode = V9FS_I(inode); 267 start: 268 page = grab_cache_page_write_begin(mapping, index, flags); 269 if (!page) { 270 retval = -ENOMEM; 271 goto out; 272 } 273 BUG_ON(!v9inode->writeback_fid); 274 if (PageUptodate(page)) 275 goto out; 276 277 if (len == PAGE_SIZE) 278 goto out; 279 280 retval = v9fs_fid_readpage(v9inode->writeback_fid, page); 281 put_page(page); 282 if (!retval) 283 goto start; 284 out: 285 *pagep = page; 286 return retval; 287 } 288 289 static int v9fs_write_end(struct file *filp, struct address_space *mapping, 290 loff_t pos, unsigned len, unsigned copied, 291 struct page *page, void *fsdata) 292 { 293 loff_t last_pos = pos + copied; 294 struct inode *inode = page->mapping->host; 295 296 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); 297 298 if (!PageUptodate(page)) { 299 if (unlikely(copied < len)) { 300 copied = 0; 301 goto out; 302 } else if (len == PAGE_SIZE) { 303 SetPageUptodate(page); 304 } 305 } 306 /* 307 * No need to use i_size_read() here, the i_size 308 * cannot change under us because we hold the i_mutex. 309 */ 310 if (last_pos > inode->i_size) { 311 inode_add_bytes(inode, last_pos - inode->i_size); 312 i_size_write(inode, last_pos); 313 } 314 set_page_dirty(page); 315 out: 316 unlock_page(page); 317 put_page(page); 318 319 return copied; 320 } 321 322 323 const struct address_space_operations v9fs_addr_operations = { 324 .readpage = v9fs_vfs_readpage, 325 .readpages = v9fs_vfs_readpages, 326 .set_page_dirty = __set_page_dirty_nobuffers, 327 .writepage = v9fs_vfs_writepage, 328 .write_begin = v9fs_write_begin, 329 .write_end = v9fs_write_end, 330 .releasepage = v9fs_release_page, 331 .invalidatepage = v9fs_invalidate_page, 332 .launder_page = v9fs_launder_page, 333 .direct_IO = v9fs_direct_IO, 334 }; 335