1 /* 2 * High-level sync()-related operations 3 */ 4 5 #include <linux/kernel.h> 6 #include <linux/file.h> 7 #include <linux/fs.h> 8 #include <linux/module.h> 9 #include <linux/sched.h> 10 #include <linux/writeback.h> 11 #include <linux/syscalls.h> 12 #include <linux/linkage.h> 13 #include <linux/pagemap.h> 14 #include <linux/quotaops.h> 15 #include <linux/buffer_head.h> 16 17 #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \ 18 SYNC_FILE_RANGE_WAIT_AFTER) 19 20 /* 21 * sync everything. Start out by waking pdflush, because that writes back 22 * all queues in parallel. 23 */ 24 static void do_sync(unsigned long wait) 25 { 26 wakeup_pdflush(0); 27 sync_inodes(0); /* All mappings, inodes and their blockdevs */ 28 DQUOT_SYNC(NULL); 29 sync_supers(); /* Write the superblocks */ 30 sync_filesystems(0); /* Start syncing the filesystems */ 31 sync_filesystems(wait); /* Waitingly sync the filesystems */ 32 sync_inodes(wait); /* Mappings, inodes and blockdevs, again. */ 33 if (!wait) 34 printk("Emergency Sync complete\n"); 35 if (unlikely(laptop_mode)) 36 laptop_sync_completion(); 37 } 38 39 SYSCALL_DEFINE0(sync) 40 { 41 do_sync(1); 42 return 0; 43 } 44 45 void emergency_sync(void) 46 { 47 pdflush_operation(do_sync, 0); 48 } 49 50 /* 51 * Generic function to fsync a file. 52 * 53 * filp may be NULL if called via the msync of a vma. 54 */ 55 int file_fsync(struct file *filp, struct dentry *dentry, int datasync) 56 { 57 struct inode * inode = dentry->d_inode; 58 struct super_block * sb; 59 int ret, err; 60 61 /* sync the inode to buffers */ 62 ret = write_inode_now(inode, 0); 63 64 /* sync the superblock to buffers */ 65 sb = inode->i_sb; 66 lock_super(sb); 67 if (sb->s_dirt && sb->s_op->write_super) 68 sb->s_op->write_super(sb); 69 unlock_super(sb); 70 71 /* .. finally sync the buffers to disk */ 72 err = sync_blockdev(sb->s_bdev); 73 if (!ret) 74 ret = err; 75 return ret; 76 } 77 78 /** 79 * vfs_fsync - perform a fsync or fdatasync on a file 80 * @file: file to sync 81 * @dentry: dentry of @file 82 * @data: only perform a fdatasync operation 83 * 84 * Write back data and metadata for @file to disk. If @datasync is 85 * set only metadata needed to access modified file data is written. 86 * 87 * In case this function is called from nfsd @file may be %NULL and 88 * only @dentry is set. This can only happen when the filesystem 89 * implements the export_operations API. 90 */ 91 int vfs_fsync(struct file *file, struct dentry *dentry, int datasync) 92 { 93 const struct file_operations *fop; 94 struct address_space *mapping; 95 int err, ret; 96 97 /* 98 * Get mapping and operations from the file in case we have 99 * as file, or get the default values for them in case we 100 * don't have a struct file available. Damn nfsd.. 101 */ 102 if (file) { 103 mapping = file->f_mapping; 104 fop = file->f_op; 105 } else { 106 mapping = dentry->d_inode->i_mapping; 107 fop = dentry->d_inode->i_fop; 108 } 109 110 if (!fop || !fop->fsync) { 111 ret = -EINVAL; 112 goto out; 113 } 114 115 ret = filemap_fdatawrite(mapping); 116 117 /* 118 * We need to protect against concurrent writers, which could cause 119 * livelocks in fsync_buffers_list(). 120 */ 121 mutex_lock(&mapping->host->i_mutex); 122 err = fop->fsync(file, dentry, datasync); 123 if (!ret) 124 ret = err; 125 mutex_unlock(&mapping->host->i_mutex); 126 err = filemap_fdatawait(mapping); 127 if (!ret) 128 ret = err; 129 out: 130 return ret; 131 } 132 EXPORT_SYMBOL(vfs_fsync); 133 134 static int do_fsync(unsigned int fd, int datasync) 135 { 136 struct file *file; 137 int ret = -EBADF; 138 139 file = fget(fd); 140 if (file) { 141 ret = vfs_fsync(file, file->f_path.dentry, datasync); 142 fput(file); 143 } 144 return ret; 145 } 146 147 SYSCALL_DEFINE1(fsync, unsigned int, fd) 148 { 149 return do_fsync(fd, 0); 150 } 151 152 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 153 { 154 return do_fsync(fd, 1); 155 } 156 157 /* 158 * sys_sync_file_range() permits finely controlled syncing over a segment of 159 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 160 * zero then sys_sync_file_range() will operate from offset out to EOF. 161 * 162 * The flag bits are: 163 * 164 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 165 * before performing the write. 166 * 167 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 168 * range which are not presently under writeback. Note that this may block for 169 * significant periods due to exhaustion of disk request structures. 170 * 171 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 172 * after performing the write. 173 * 174 * Useful combinations of the flag bits are: 175 * 176 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 177 * in the range which were dirty on entry to sys_sync_file_range() are placed 178 * under writeout. This is a start-write-for-data-integrity operation. 179 * 180 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 181 * are not presently under writeout. This is an asynchronous flush-to-disk 182 * operation. Not suitable for data integrity operations. 183 * 184 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 185 * completion of writeout of all pages in the range. This will be used after an 186 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 187 * for that operation to complete and to return the result. 188 * 189 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: 190 * a traditional sync() operation. This is a write-for-data-integrity operation 191 * which will ensure that all pages in the range which were dirty on entry to 192 * sys_sync_file_range() are committed to disk. 193 * 194 * 195 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 196 * I/O errors or ENOSPC conditions and will return those to the caller, after 197 * clearing the EIO and ENOSPC flags in the address_space. 198 * 199 * It should be noted that none of these operations write out the file's 200 * metadata. So unless the application is strictly performing overwrites of 201 * already-instantiated disk blocks, there are no guarantees here that the data 202 * will be available after a crash. 203 */ 204 SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes, 205 unsigned int flags) 206 { 207 int ret; 208 struct file *file; 209 loff_t endbyte; /* inclusive */ 210 int fput_needed; 211 umode_t i_mode; 212 213 ret = -EINVAL; 214 if (flags & ~VALID_FLAGS) 215 goto out; 216 217 endbyte = offset + nbytes; 218 219 if ((s64)offset < 0) 220 goto out; 221 if ((s64)endbyte < 0) 222 goto out; 223 if (endbyte < offset) 224 goto out; 225 226 if (sizeof(pgoff_t) == 4) { 227 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 228 /* 229 * The range starts outside a 32 bit machine's 230 * pagecache addressing capabilities. Let it "succeed" 231 */ 232 ret = 0; 233 goto out; 234 } 235 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 236 /* 237 * Out to EOF 238 */ 239 nbytes = 0; 240 } 241 } 242 243 if (nbytes == 0) 244 endbyte = LLONG_MAX; 245 else 246 endbyte--; /* inclusive */ 247 248 ret = -EBADF; 249 file = fget_light(fd, &fput_needed); 250 if (!file) 251 goto out; 252 253 i_mode = file->f_path.dentry->d_inode->i_mode; 254 ret = -ESPIPE; 255 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 256 !S_ISLNK(i_mode)) 257 goto out_put; 258 259 ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags); 260 out_put: 261 fput_light(file, fput_needed); 262 out: 263 return ret; 264 } 265 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 266 asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes, 267 long flags) 268 { 269 return SYSC_sync_file_range((int) fd, offset, nbytes, 270 (unsigned int) flags); 271 } 272 SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range); 273 #endif 274 275 /* It would be nice if people remember that not all the world's an i386 276 when they introduce new system calls */ 277 SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags, 278 loff_t offset, loff_t nbytes) 279 { 280 return sys_sync_file_range(fd, offset, nbytes, flags); 281 } 282 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 283 asmlinkage long SyS_sync_file_range2(long fd, long flags, 284 loff_t offset, loff_t nbytes) 285 { 286 return SYSC_sync_file_range2((int) fd, (unsigned int) flags, 287 offset, nbytes); 288 } 289 SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2); 290 #endif 291 292 /* 293 * `endbyte' is inclusive 294 */ 295 int do_sync_mapping_range(struct address_space *mapping, loff_t offset, 296 loff_t endbyte, unsigned int flags) 297 { 298 int ret; 299 300 if (!mapping) { 301 ret = -EINVAL; 302 goto out; 303 } 304 305 ret = 0; 306 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 307 ret = wait_on_page_writeback_range(mapping, 308 offset >> PAGE_CACHE_SHIFT, 309 endbyte >> PAGE_CACHE_SHIFT); 310 if (ret < 0) 311 goto out; 312 } 313 314 if (flags & SYNC_FILE_RANGE_WRITE) { 315 ret = __filemap_fdatawrite_range(mapping, offset, endbyte, 316 WB_SYNC_ALL); 317 if (ret < 0) 318 goto out; 319 } 320 321 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) { 322 ret = wait_on_page_writeback_range(mapping, 323 offset >> PAGE_CACHE_SHIFT, 324 endbyte >> PAGE_CACHE_SHIFT); 325 } 326 out: 327 return ret; 328 } 329 EXPORT_SYMBOL_GPL(do_sync_mapping_range); 330