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 */
do_sync(unsigned long wait)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
SYSCALL_DEFINE0(sync)39 SYSCALL_DEFINE0(sync)
40 {
41 do_sync(1);
42 return 0;
43 }
44
emergency_sync(void)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 */
file_fsync(struct file * filp,struct dentry * dentry,int datasync)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 */
vfs_fsync(struct file * file,struct dentry * dentry,int datasync)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
do_fsync(unsigned int fd,int datasync)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
SYSCALL_DEFINE1(fsync,unsigned int,fd)147 SYSCALL_DEFINE1(fsync, unsigned int, fd)
148 {
149 return do_fsync(fd, 0);
150 }
151
SYSCALL_DEFINE1(fdatasync,unsigned int,fd)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 */
SYSCALL_DEFINE(sync_file_range)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
SyS_sync_file_range(long fd,loff_t offset,loff_t nbytes,long flags)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 */
SYSCALL_DEFINE(sync_file_range2)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
SyS_sync_file_range2(long fd,long flags,loff_t offset,loff_t nbytes)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 */
do_sync_mapping_range(struct address_space * mapping,loff_t offset,loff_t endbyte,unsigned int flags)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