fs/sync.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * High-level sync()-related operations
   4  */
   5
   6 #include <linux/blkdev.h>
   7 #include <linux/kernel.h>
   8 #include <linux/file.h>
   9 #include <linux/fs.h>
  10 #include <linux/slab.h>
  11 #include <linux/export.h>
  12 #include <linux/namei.h>
  13 #include <linux/sched.h>
  14 #include <linux/writeback.h>
  15 #include <linux/syscalls.h>
  16 #include <linux/linkage.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/quotaops.h>
  19 #include <linux/backing-dev.h>
  20 #include "internal.h"
  21
  22 #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
  23                         SYNC_FILE_RANGE_WAIT_AFTER)
  24
  25 /*
  26  * Write out and wait upon all dirty data associated with this
  27  * superblock.  Filesystem data as well as the underlying block
  28  * device.  Takes the superblock lock.
  29  */
  30 int sync_filesystem(struct super_block *sb)
  31 {
  32         int ret = 0;
  33
  34         /*
  35          * We need to be protected against the filesystem going from
  36          * r/o to r/w or vice versa.
  37          */
  38         WARN_ON(!rwsem_is_locked(&sb->s_umount));
  39
  40         /*
  41          * No point in syncing out anything if the filesystem is read-only.
  42          */
  43         if (sb_rdonly(sb))
  44                 return 0;
  45
  46         /*
  47          * Do the filesystem syncing work.  For simple filesystems
  48          * writeback_inodes_sb(sb) just dirties buffers with inodes so we have
  49          * to submit I/O for these buffers via sync_blockdev().  This also
  50          * speeds up the wait == 1 case since in that case write_inode()
  51          * methods call sync_dirty_buffer() and thus effectively write one block
  52          * at a time.
  53          */
  54         writeback_inodes_sb(sb, WB_REASON_SYNC);
  55         if (sb->s_op->sync_fs) {
  56                 ret = sb->s_op->sync_fs(sb, 0);
  57                 if (ret)
  58                         return ret;
  59         }
  60         ret = sync_blockdev_nowait(sb->s_bdev);
  61         if (ret)
  62                 return ret;
  63
  64         sync_inodes_sb(sb);
  65         if (sb->s_op->sync_fs) {
  66                 ret = sb->s_op->sync_fs(sb, 1);
  67                 if (ret)
  68                         return ret;
  69         }
  70         return sync_blockdev(sb->s_bdev);
  71 }
  72 EXPORT_SYMBOL(sync_filesystem);
  73
  74 static void sync_inodes_one_sb(struct super_block *sb, void *arg)
  75 {
  76         if (!sb_rdonly(sb))
  77                 sync_inodes_sb(sb);
  78 }
  79
  80 static void sync_fs_one_sb(struct super_block *sb, void *arg)
  81 {
  82         if (!sb_rdonly(sb) && !(sb->s_iflags & SB_I_SKIP_SYNC) &&
  83             sb->s_op->sync_fs)
  84                 sb->s_op->sync_fs(sb, *(int *)arg);
  85 }
  86
  87 /*
  88  * Sync everything. We start by waking flusher threads so that most of
  89  * writeback runs on all devices in parallel. Then we sync all inodes reliably
  90  * which effectively also waits for all flusher threads to finish doing
  91  * writeback. At this point all data is on disk so metadata should be stable
  92  * and we tell filesystems to sync their metadata via ->sync_fs() calls.
  93  * Finally, we writeout all block devices because some filesystems (e.g. ext2)
  94  * just write metadata (such as inodes or bitmaps) to block device page cache
  95  * and do not sync it on their own in ->sync_fs().
  96  */
  97 void ksys_sync(void)
  98 {
  99         int nowait = 0, wait = 1;
 100
 101         wakeup_flusher_threads(WB_REASON_SYNC);
 102         iterate_supers(sync_inodes_one_sb, NULL);
 103         iterate_supers(sync_fs_one_sb, &nowait);
 104         iterate_supers(sync_fs_one_sb, &wait);
 105         sync_bdevs(false);
 106         sync_bdevs(true);
 107         if (unlikely(laptop_mode))
 108                 laptop_sync_completion();
 109 }
 110
 111 SYSCALL_DEFINE0(sync)
 112 {
 113         ksys_sync();
 114         return 0;
 115 }
 116
 117 static void do_sync_work(struct work_struct *work)
 118 {
 119         int nowait = 0;
 120
 121         /*
 122          * Sync twice to reduce the possibility we skipped some inodes / pages
 123          * because they were temporarily locked
 124          */
 125         iterate_supers(sync_inodes_one_sb, &nowait);
 126         iterate_supers(sync_fs_one_sb, &nowait);
 127         sync_bdevs(false);
 128         iterate_supers(sync_inodes_one_sb, &nowait);
 129         iterate_supers(sync_fs_one_sb, &nowait);
 130         sync_bdevs(false);
 131         printk("Emergency Sync complete\n");
 132         kfree(work);
 133 }
 134
 135 void emergency_sync(void)
 136 {
 137         struct work_struct *work;
 138
 139         work = kmalloc(sizeof(*work), GFP_ATOMIC);
 140         if (work) {
 141                 INIT_WORK(work, do_sync_work);
 142                 schedule_work(work);
 143         }
 144 }
 145
 146 /*
 147  * sync a single super
 148  */
 149 SYSCALL_DEFINE1(syncfs, int, fd)
 150 {
 151         CLASS(fd, f)(fd);
 152         struct super_block *sb;
 153         int ret, ret2;
 154
 155         if (fd_empty(f))
 156                 return -EBADF;
 157         sb = fd_file(f)->f_path.dentry->d_sb;
 158
 159         down_read(&sb->s_umount);
 160         ret = sync_filesystem(sb);
 161         up_read(&sb->s_umount);
 162
 163         ret2 = errseq_check_and_advance(&sb->s_wb_err, &fd_file(f)->f_sb_err);
 164
 165         return ret ? ret : ret2;
 166 }
 167
 168 /**
 169  * vfs_fsync_range - helper to sync a range of data & metadata to disk
 170  * @file:               file to sync
 171  * @start:              offset in bytes of the beginning of data range to sync
 172  * @end:                offset in bytes of the end of data range (inclusive)
 173  * @datasync:           perform only datasync
 174  *
 175  * Write back data in range @start..@end and metadata for @file to disk.  If
 176  * @datasync is set only metadata needed to access modified file data is
 177  * written.
 178  */
 179 int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
 180 {
 181         struct inode *inode = file->f_mapping->host;
 182
 183         if (!file->f_op->fsync)
 184                 return -EINVAL;
 185         if (!datasync && (inode->i_state & I_DIRTY_TIME))
 186                 mark_inode_dirty_sync(inode);
 187         return file->f_op->fsync(file, start, end, datasync);
 188 }
 189 EXPORT_SYMBOL(vfs_fsync_range);
 190
 191 /**
 192  * vfs_fsync - perform a fsync or fdatasync on a file
 193  * @file:               file to sync
 194  * @datasync:           only perform a fdatasync operation
 195  *
 196  * Write back data and metadata for @file to disk.  If @datasync is
 197  * set only metadata needed to access modified file data is written.
 198  */
 199 int vfs_fsync(struct file *file, int datasync)
 200 {
 201         return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
 202 }
 203 EXPORT_SYMBOL(vfs_fsync);
 204
 205 static int do_fsync(unsigned int fd, int datasync)
 206 {
 207         CLASS(fd, f)(fd);
 208
 209         if (fd_empty(f))
 210                 return -EBADF;
 211
 212         return vfs_fsync(fd_file(f), datasync);
 213 }
 214
 215 SYSCALL_DEFINE1(fsync, unsigned int, fd)
 216 {
 217         return do_fsync(fd, 0);
 218 }
 219
 220 SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
 221 {
 222         return do_fsync(fd, 1);
 223 }
 224
 225 int sync_file_range(struct file *file, loff_t offset, loff_t nbytes,
 226                     unsigned int flags)
 227 {
 228         int ret;
 229         struct address_space *mapping;
 230         loff_t endbyte;                 /* inclusive */
 231         umode_t i_mode;
 232
 233         ret = -EINVAL;
 234         if (flags & ~VALID_FLAGS)
 235                 goto out;
 236
 237         endbyte = offset + nbytes;
 238
 239         if ((s64)offset < 0)
 240                 goto out;
 241         if ((s64)endbyte < 0)
 242                 goto out;
 243         if (endbyte < offset)
 244                 goto out;
 245
 246         if (sizeof(pgoff_t) == 4) {
 247                 if (offset >= (0x100000000ULL << PAGE_SHIFT)) {
 248                         /*
 249                          * The range starts outside a 32 bit machine's
 250                          * pagecache addressing capabilities.  Let it "succeed"
 251                          */
 252                         ret = 0;
 253                         goto out;
 254                 }
 255                 if (endbyte >= (0x100000000ULL << PAGE_SHIFT)) {
 256                         /*
 257                          * Out to EOF
 258                          */
 259                         nbytes = 0;
 260                 }
 261         }
 262
 263         if (nbytes == 0)
 264                 endbyte = LLONG_MAX;
 265         else
 266                 endbyte--;              /* inclusive */
 267
 268         i_mode = file_inode(file)->i_mode;
 269         ret = -ESPIPE;
 270         if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
 271                         !S_ISLNK(i_mode))
 272                 goto out;
 273
 274         mapping = file->f_mapping;
 275         ret = 0;
 276         if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
 277                 ret = file_fdatawait_range(file, offset, endbyte);
 278                 if (ret < 0)
 279                         goto out;
 280         }
 281
 282         if (flags & SYNC_FILE_RANGE_WRITE) {
 283                 int sync_mode = WB_SYNC_NONE;
 284
 285                 if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) ==
 286                              SYNC_FILE_RANGE_WRITE_AND_WAIT)
 287                         sync_mode = WB_SYNC_ALL;
 288
 289                 ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
 290                                                  sync_mode);
 291                 if (ret < 0)
 292                         goto out;
 293         }
 294
 295         if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
 296                 ret = file_fdatawait_range(file, offset, endbyte);
 297
 298 out:
 299         return ret;
 300 }
 301
 302 /*
 303  * ksys_sync_file_range() permits finely controlled syncing over a segment of
 304  * a file in the range offset .. (offset+nbytes-1) inclusive.  If nbytes is
 305  * zero then ksys_sync_file_range() will operate from offset out to EOF.
 306  *
 307  * The flag bits are:
 308  *
 309  * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
 310  * before performing the write.
 311  *
 312  * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
 313  * range which are not presently under writeback. Note that this may block for
 314  * significant periods due to exhaustion of disk request structures.
 315  *
 316  * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
 317  * after performing the write.
 318  *
 319  * Useful combinations of the flag bits are:
 320  *
 321  * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
 322  * in the range which were dirty on entry to ksys_sync_file_range() are placed
 323  * under writeout.  This is a start-write-for-data-integrity operation.
 324  *
 325  * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
 326  * are not presently under writeout.  This is an asynchronous flush-to-disk
 327  * operation.  Not suitable for data integrity operations.
 328  *
 329  * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
 330  * completion of writeout of all pages in the range.  This will be used after an
 331  * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
 332  * for that operation to complete and to return the result.
 333  *
 334  * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER
 335  * (a.k.a. SYNC_FILE_RANGE_WRITE_AND_WAIT):
 336  * a traditional sync() operation.  This is a write-for-data-integrity operation
 337  * which will ensure that all pages in the range which were dirty on entry to
 338  * ksys_sync_file_range() are written to disk.  It should be noted that disk
 339  * caches are not flushed by this call, so there are no guarantees here that the
 340  * data will be available on disk after a crash.
 341  *
 342  *
 343  * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
 344  * I/O errors or ENOSPC conditions and will return those to the caller, after
 345  * clearing the EIO and ENOSPC flags in the address_space.
 346  *
 347  * It should be noted that none of these operations write out the file's
 348  * metadata.  So unless the application is strictly performing overwrites of
 349  * already-instantiated disk blocks, there are no guarantees here that the data
 350  * will be available after a crash.
 351  */
 352 int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
 353                          unsigned int flags)
 354 {
 355         CLASS(fd, f)(fd);
 356
 357         if (fd_empty(f))
 358                 return -EBADF;
 359
 360         return sync_file_range(fd_file(f), offset, nbytes, flags);
 361 }
 362
 363 SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
 364                                 unsigned int, flags)
 365 {
 366         return ksys_sync_file_range(fd, offset, nbytes, flags);
 367 }
 368
 369 #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_SYNC_FILE_RANGE)
 370 COMPAT_SYSCALL_DEFINE6(sync_file_range, int, fd, compat_arg_u64_dual(offset),
 371                        compat_arg_u64_dual(nbytes), unsigned int, flags)
 372 {
 373         return ksys_sync_file_range(fd, compat_arg_u64_glue(offset),
 374                                     compat_arg_u64_glue(nbytes), flags);
 375 }
 376 #endif
 377
 378 /* It would be nice if people remember that not all the world's an i386
 379    when they introduce new system calls */
 380 SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags,
 381                                  loff_t, offset, loff_t, nbytes)
 382 {
 383         return ksys_sync_file_range(fd, offset, nbytes, flags);
 384 }