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 vfs_dq_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 static void do_sync_work(struct work_struct *work) 46 { 47 do_sync(0); 48 kfree(work); 49 } 50 51 void emergency_sync(void) 52 { 53 struct work_struct *work; 54 55 work = kmalloc(sizeof(*work), GFP_ATOMIC); 56 if (work) { 57 INIT_WORK(work, do_sync_work); 58 schedule_work(work); 59 } 60 } 61 62 /* 63 * Generic function to fsync a file. 64 * 65 * filp may be NULL if called via the msync of a vma. 66 */ 67 int file_fsync(struct file *filp, struct dentry *dentry, int datasync) 68 { 69 struct inode * inode = dentry->d_inode; 70 struct super_block * sb; 71 int ret, err; 72 73 /* sync the inode to buffers */ 74 ret = write_inode_now(inode, 0); 75 76 /* sync the superblock to buffers */ 77 sb = inode->i_sb; 78 lock_super(sb); 79 if (sb->s_dirt && sb->s_op->write_super) 80 sb->s_op->write_super(sb); 81 unlock_super(sb); 82 83 /* .. finally sync the buffers to disk */ 84 err = sync_blockdev(sb->s_bdev); 85 if (!ret) 86 ret = err; 87 return ret; 88 } 89 90 /** 91 * vfs_fsync - perform a fsync or fdatasync on a file 92 * @file: file to sync 93 * @dentry: dentry of @file 94 * @data: only perform a fdatasync operation 95 * 96 * Write back data and metadata for @file to disk. If @datasync is 97 * set only metadata needed to access modified file data is written. 98 * 99 * In case this function is called from nfsd @file may be %NULL and 100 * only @dentry is set. This can only happen when the filesystem 101 * implements the export_operations API. 102 */ 103 int vfs_fsync(struct file *file, struct dentry *dentry, int datasync) 104 { 105 const struct file_operations *fop; 106 struct address_space *mapping; 107 int err, ret; 108 109 /* 110 * Get mapping and operations from the file in case we have 111 * as file, or get the default values for them in case we 112 * don't have a struct file available. Damn nfsd.. 113 */ 114 if (file) { 115 mapping = file->f_mapping; 116 fop = file->f_op; 117 } else { 118 mapping = dentry->d_inode->i_mapping; 119 fop = dentry->d_inode->i_fop; 120 } 121 122 if (!fop || !fop->fsync) { 123 ret = -EINVAL; 124 goto out; 125 } 126 127 ret = filemap_fdatawrite(mapping); 128 129 /* 130 * We need to protect against concurrent writers, which could cause 131 * livelocks in fsync_buffers_list(). 132 */ 133 mutex_lock(&mapping->host->i_mutex); 134 err = fop->fsync(file, dentry, datasync); 135 if (!ret) 136 ret = err; 137 mutex_unlock(&mapping->host->i_mutex); 138 err = filemap_fdatawait(mapping); 139 if (!ret) 140 ret = err; 141 out: 142 return ret; 143 } 144 EXPORT_SYMBOL(vfs_fsync); 145 146 static int do_fsync(unsigned int fd, int datasync) 147 { 148 struct file *file; 149 int ret = -EBADF; 150 151 file = fget(fd); 152 if (file) { 153 ret = vfs_fsync(file, file->f_path.dentry, datasync); 154 fput(file); 155 } 156 return ret; 157 } 158 159 SYSCALL_DEFINE1(fsync, unsigned int, fd) 160 { 161 return do_fsync(fd, 0); 162 } 163 164 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 165 { 166 return do_fsync(fd, 1); 167 } 168 169 /* 170 * sys_sync_file_range() permits finely controlled syncing over a segment of 171 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 172 * zero then sys_sync_file_range() will operate from offset out to EOF. 173 * 174 * The flag bits are: 175 * 176 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 177 * before performing the write. 178 * 179 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 180 * range which are not presently under writeback. Note that this may block for 181 * significant periods due to exhaustion of disk request structures. 182 * 183 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 184 * after performing the write. 185 * 186 * Useful combinations of the flag bits are: 187 * 188 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 189 * in the range which were dirty on entry to sys_sync_file_range() are placed 190 * under writeout. This is a start-write-for-data-integrity operation. 191 * 192 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 193 * are not presently under writeout. This is an asynchronous flush-to-disk 194 * operation. Not suitable for data integrity operations. 195 * 196 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 197 * completion of writeout of all pages in the range. This will be used after an 198 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 199 * for that operation to complete and to return the result. 200 * 201 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: 202 * a traditional sync() operation. This is a write-for-data-integrity operation 203 * which will ensure that all pages in the range which were dirty on entry to 204 * sys_sync_file_range() are committed to disk. 205 * 206 * 207 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 208 * I/O errors or ENOSPC conditions and will return those to the caller, after 209 * clearing the EIO and ENOSPC flags in the address_space. 210 * 211 * It should be noted that none of these operations write out the file's 212 * metadata. So unless the application is strictly performing overwrites of 213 * already-instantiated disk blocks, there are no guarantees here that the data 214 * will be available after a crash. 215 */ 216 SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes, 217 unsigned int flags) 218 { 219 int ret; 220 struct file *file; 221 loff_t endbyte; /* inclusive */ 222 int fput_needed; 223 umode_t i_mode; 224 225 ret = -EINVAL; 226 if (flags & ~VALID_FLAGS) 227 goto out; 228 229 endbyte = offset + nbytes; 230 231 if ((s64)offset < 0) 232 goto out; 233 if ((s64)endbyte < 0) 234 goto out; 235 if (endbyte < offset) 236 goto out; 237 238 if (sizeof(pgoff_t) == 4) { 239 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 240 /* 241 * The range starts outside a 32 bit machine's 242 * pagecache addressing capabilities. Let it "succeed" 243 */ 244 ret = 0; 245 goto out; 246 } 247 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 248 /* 249 * Out to EOF 250 */ 251 nbytes = 0; 252 } 253 } 254 255 if (nbytes == 0) 256 endbyte = LLONG_MAX; 257 else 258 endbyte--; /* inclusive */ 259 260 ret = -EBADF; 261 file = fget_light(fd, &fput_needed); 262 if (!file) 263 goto out; 264 265 i_mode = file->f_path.dentry->d_inode->i_mode; 266 ret = -ESPIPE; 267 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 268 !S_ISLNK(i_mode)) 269 goto out_put; 270 271 ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags); 272 out_put: 273 fput_light(file, fput_needed); 274 out: 275 return ret; 276 } 277 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 278 asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes, 279 long flags) 280 { 281 return SYSC_sync_file_range((int) fd, offset, nbytes, 282 (unsigned int) flags); 283 } 284 SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range); 285 #endif 286 287 /* It would be nice if people remember that not all the world's an i386 288 when they introduce new system calls */ 289 SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags, 290 loff_t offset, loff_t nbytes) 291 { 292 return sys_sync_file_range(fd, offset, nbytes, flags); 293 } 294 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 295 asmlinkage long SyS_sync_file_range2(long fd, long flags, 296 loff_t offset, loff_t nbytes) 297 { 298 return SYSC_sync_file_range2((int) fd, (unsigned int) flags, 299 offset, nbytes); 300 } 301 SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2); 302 #endif 303 304 /* 305 * `endbyte' is inclusive 306 */ 307 int do_sync_mapping_range(struct address_space *mapping, loff_t offset, 308 loff_t endbyte, unsigned int flags) 309 { 310 int ret; 311 312 if (!mapping) { 313 ret = -EINVAL; 314 goto out; 315 } 316 317 ret = 0; 318 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 319 ret = wait_on_page_writeback_range(mapping, 320 offset >> PAGE_CACHE_SHIFT, 321 endbyte >> PAGE_CACHE_SHIFT); 322 if (ret < 0) 323 goto out; 324 } 325 326 if (flags & SYNC_FILE_RANGE_WRITE) { 327 ret = __filemap_fdatawrite_range(mapping, offset, endbyte, 328 WB_SYNC_ALL); 329 if (ret < 0) 330 goto out; 331 } 332 333 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) { 334 ret = wait_on_page_writeback_range(mapping, 335 offset >> PAGE_CACHE_SHIFT, 336 endbyte >> PAGE_CACHE_SHIFT); 337 } 338 out: 339 return ret; 340 } 341 EXPORT_SYMBOL_GPL(do_sync_mapping_range); 342