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 asmlinkage long sys_sync(void) 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_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 long do_fsync(struct file *file, int datasync) 79 { 80 int ret; 81 int err; 82 struct address_space *mapping = file->f_mapping; 83 84 if (!file->f_op || !file->f_op->fsync) { 85 /* Why? We can still call filemap_fdatawrite */ 86 ret = -EINVAL; 87 goto out; 88 } 89 90 ret = filemap_fdatawrite(mapping); 91 92 /* 93 * We need to protect against concurrent writers, which could cause 94 * livelocks in fsync_buffers_list(). 95 */ 96 mutex_lock(&mapping->host->i_mutex); 97 err = file->f_op->fsync(file, file->f_path.dentry, datasync); 98 if (!ret) 99 ret = err; 100 mutex_unlock(&mapping->host->i_mutex); 101 err = filemap_fdatawait(mapping); 102 if (!ret) 103 ret = err; 104 out: 105 return ret; 106 } 107 108 static long __do_fsync(unsigned int fd, int datasync) 109 { 110 struct file *file; 111 int ret = -EBADF; 112 113 file = fget(fd); 114 if (file) { 115 ret = do_fsync(file, datasync); 116 fput(file); 117 } 118 return ret; 119 } 120 121 asmlinkage long sys_fsync(unsigned int fd) 122 { 123 return __do_fsync(fd, 0); 124 } 125 126 asmlinkage long sys_fdatasync(unsigned int fd) 127 { 128 return __do_fsync(fd, 1); 129 } 130 131 /* 132 * sys_sync_file_range() permits finely controlled syncing over a segment of 133 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 134 * zero then sys_sync_file_range() will operate from offset out to EOF. 135 * 136 * The flag bits are: 137 * 138 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 139 * before performing the write. 140 * 141 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 142 * range which are not presently under writeback. 143 * 144 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 145 * after performing the write. 146 * 147 * Useful combinations of the flag bits are: 148 * 149 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 150 * in the range which were dirty on entry to sys_sync_file_range() are placed 151 * under writeout. This is a start-write-for-data-integrity operation. 152 * 153 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 154 * are not presently under writeout. This is an asynchronous flush-to-disk 155 * operation. Not suitable for data integrity operations. 156 * 157 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 158 * completion of writeout of all pages in the range. This will be used after an 159 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 160 * for that operation to complete and to return the result. 161 * 162 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: 163 * a traditional sync() operation. This is a write-for-data-integrity operation 164 * which will ensure that all pages in the range which were dirty on entry to 165 * sys_sync_file_range() are committed to disk. 166 * 167 * 168 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 169 * I/O errors or ENOSPC conditions and will return those to the caller, after 170 * clearing the EIO and ENOSPC flags in the address_space. 171 * 172 * It should be noted that none of these operations write out the file's 173 * metadata. So unless the application is strictly performing overwrites of 174 * already-instantiated disk blocks, there are no guarantees here that the data 175 * will be available after a crash. 176 */ 177 asmlinkage long sys_sync_file_range(int fd, loff_t offset, loff_t nbytes, 178 unsigned int flags) 179 { 180 int ret; 181 struct file *file; 182 loff_t endbyte; /* inclusive */ 183 int fput_needed; 184 umode_t i_mode; 185 186 ret = -EINVAL; 187 if (flags & ~VALID_FLAGS) 188 goto out; 189 190 endbyte = offset + nbytes; 191 192 if ((s64)offset < 0) 193 goto out; 194 if ((s64)endbyte < 0) 195 goto out; 196 if (endbyte < offset) 197 goto out; 198 199 if (sizeof(pgoff_t) == 4) { 200 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 201 /* 202 * The range starts outside a 32 bit machine's 203 * pagecache addressing capabilities. Let it "succeed" 204 */ 205 ret = 0; 206 goto out; 207 } 208 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 209 /* 210 * Out to EOF 211 */ 212 nbytes = 0; 213 } 214 } 215 216 if (nbytes == 0) 217 endbyte = LLONG_MAX; 218 else 219 endbyte--; /* inclusive */ 220 221 ret = -EBADF; 222 file = fget_light(fd, &fput_needed); 223 if (!file) 224 goto out; 225 226 i_mode = file->f_path.dentry->d_inode->i_mode; 227 ret = -ESPIPE; 228 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 229 !S_ISLNK(i_mode)) 230 goto out_put; 231 232 ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags); 233 out_put: 234 fput_light(file, fput_needed); 235 out: 236 return ret; 237 } 238 239 /* 240 * `endbyte' is inclusive 241 */ 242 int do_sync_mapping_range(struct address_space *mapping, loff_t offset, 243 loff_t endbyte, unsigned int flags) 244 { 245 int ret; 246 247 if (!mapping) { 248 ret = -EINVAL; 249 goto out; 250 } 251 252 ret = 0; 253 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 254 ret = wait_on_page_writeback_range(mapping, 255 offset >> PAGE_CACHE_SHIFT, 256 endbyte >> PAGE_CACHE_SHIFT); 257 if (ret < 0) 258 goto out; 259 } 260 261 if (flags & SYNC_FILE_RANGE_WRITE) { 262 ret = __filemap_fdatawrite_range(mapping, offset, endbyte, 263 WB_SYNC_NONE); 264 if (ret < 0) 265 goto out; 266 } 267 268 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) { 269 ret = wait_on_page_writeback_range(mapping, 270 offset >> PAGE_CACHE_SHIFT, 271 endbyte >> PAGE_CACHE_SHIFT); 272 } 273 out: 274 return ret; 275 } 276 EXPORT_SYMBOL_GPL(do_sync_mapping_range); 277