| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * High-level sync()-related operations |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/file.h> |
| #include <linux/fs.h> |
| #include <linux/slab.h> |
| #include <linux/export.h> |
| #include <linux/namei.h> |
| #include <linux/sched.h> |
| #include <linux/writeback.h> |
| #include <linux/syscalls.h> |
| #include <linux/linkage.h> |
| #include <linux/pagemap.h> |
| #include <linux/quotaops.h> |
| #include <linux/backing-dev.h> |
| #include "internal.h" |
| |
| #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \ |
| SYNC_FILE_RANGE_WAIT_AFTER) |
| |
| /* |
| * Do the filesystem syncing work. For simple filesystems |
| * writeback_inodes_sb(sb) just dirties buffers with inodes so we have to |
| * submit IO for these buffers via __sync_blockdev(). This also speeds up the |
| * wait == 1 case since in that case write_inode() functions do |
| * sync_dirty_buffer() and thus effectively write one block at a time. |
| */ |
| static int __sync_filesystem(struct super_block *sb, int wait) |
| { |
| if (wait) |
| sync_inodes_sb(sb); |
| else |
| writeback_inodes_sb(sb, WB_REASON_SYNC); |
| |
| if (sb->s_op->sync_fs) |
| sb->s_op->sync_fs(sb, wait); |
| return __sync_blockdev(sb->s_bdev, wait); |
| } |
| |
| /* |
| * Write out and wait upon all dirty data associated with this |
| * superblock. Filesystem data as well as the underlying block |
| * device. Takes the superblock lock. |
| */ |
| int sync_filesystem(struct super_block *sb) |
| { |
| int ret; |
| |
| /* |
| * We need to be protected against the filesystem going from |
| * r/o to r/w or vice versa. |
| */ |
| WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
| |
| /* |
| * No point in syncing out anything if the filesystem is read-only. |
| */ |
| if (sb_rdonly(sb)) |
| return 0; |
| |
| ret = __sync_filesystem(sb, 0); |
| if (ret < 0) |
| return ret; |
| return __sync_filesystem(sb, 1); |
| } |
| EXPORT_SYMBOL(sync_filesystem); |
| |
| static void sync_inodes_one_sb(struct super_block *sb, void *arg) |
| { |
| if (!sb_rdonly(sb)) |
| sync_inodes_sb(sb); |
| } |
| |
| static void sync_fs_one_sb(struct super_block *sb, void *arg) |
| { |
| if (!sb_rdonly(sb) && sb->s_op->sync_fs) |
| sb->s_op->sync_fs(sb, *(int *)arg); |
| } |
| |
| static void fdatawrite_one_bdev(struct block_device *bdev, void *arg) |
| { |
| filemap_fdatawrite(bdev->bd_inode->i_mapping); |
| } |
| |
| static void fdatawait_one_bdev(struct block_device *bdev, void *arg) |
| { |
| /* |
| * We keep the error status of individual mapping so that |
| * applications can catch the writeback error using fsync(2). |
| * See filemap_fdatawait_keep_errors() for details. |
| */ |
| filemap_fdatawait_keep_errors(bdev->bd_inode->i_mapping); |
| } |
| |
| /* |
| * Sync everything. We start by waking flusher threads so that most of |
| * writeback runs on all devices in parallel. Then we sync all inodes reliably |
| * which effectively also waits for all flusher threads to finish doing |
| * writeback. At this point all data is on disk so metadata should be stable |
| * and we tell filesystems to sync their metadata via ->sync_fs() calls. |
| * Finally, we writeout all block devices because some filesystems (e.g. ext2) |
| * just write metadata (such as inodes or bitmaps) to block device page cache |
| * and do not sync it on their own in ->sync_fs(). |
| */ |
| void ksys_sync(void) |
| { |
| int nowait = 0, wait = 1; |
| |
| wakeup_flusher_threads(WB_REASON_SYNC); |
| iterate_supers(sync_inodes_one_sb, NULL); |
| iterate_supers(sync_fs_one_sb, &nowait); |
| iterate_supers(sync_fs_one_sb, &wait); |
| iterate_bdevs(fdatawrite_one_bdev, NULL); |
| iterate_bdevs(fdatawait_one_bdev, NULL); |
| if (unlikely(laptop_mode)) |
| laptop_sync_completion(); |
| } |
| |
| SYSCALL_DEFINE0(sync) |
| { |
| ksys_sync(); |
| return 0; |
| } |
| |
| static void do_sync_work(struct work_struct *work) |
| { |
| int nowait = 0; |
| |
| /* |
| * Sync twice to reduce the possibility we skipped some inodes / pages |
| * because they were temporarily locked |
| */ |
| iterate_supers(sync_inodes_one_sb, &nowait); |
| iterate_supers(sync_fs_one_sb, &nowait); |
| iterate_bdevs(fdatawrite_one_bdev, NULL); |
| iterate_supers(sync_inodes_one_sb, &nowait); |
| iterate_supers(sync_fs_one_sb, &nowait); |
| iterate_bdevs(fdatawrite_one_bdev, NULL); |
| printk("Emergency Sync complete\n"); |
| kfree(work); |
| } |
| |
| void emergency_sync(void) |
| { |
| struct work_struct *work; |
| |
| work = kmalloc(sizeof(*work), GFP_ATOMIC); |
| if (work) { |
| INIT_WORK(work, do_sync_work); |
| schedule_work(work); |
| } |
| } |
| |
| /* |
| * sync a single super |
| */ |
| SYSCALL_DEFINE1(syncfs, int, fd) |
| { |
| struct fd f = fdget(fd); |
| struct super_block *sb; |
| int ret; |
| |
| if (!f.file) |
| return -EBADF; |
| sb = f.file->f_path.dentry->d_sb; |
| |
| down_read(&sb->s_umount); |
| ret = sync_filesystem(sb); |
| up_read(&sb->s_umount); |
| |
| fdput(f); |
| return ret; |
| } |
| |
| /** |
| * vfs_fsync_range - helper to sync a range of data & metadata to disk |
| * @file: file to sync |
| * @start: offset in bytes of the beginning of data range to sync |
| * @end: offset in bytes of the end of data range (inclusive) |
| * @datasync: perform only datasync |
| * |
| * Write back data in range @start..@end and metadata for @file to disk. If |
| * @datasync is set only metadata needed to access modified file data is |
| * written. |
| */ |
| int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) |
| { |
| struct inode *inode = file->f_mapping->host; |
| |
| if (!file->f_op->fsync) |
| return -EINVAL; |
| if (!datasync && (inode->i_state & I_DIRTY_TIME)) { |
| spin_lock(&inode->i_lock); |
| inode->i_state &= ~I_DIRTY_TIME; |
| spin_unlock(&inode->i_lock); |
| mark_inode_dirty_sync(inode); |
| } |
| return file->f_op->fsync(file, start, end, datasync); |
| } |
| EXPORT_SYMBOL(vfs_fsync_range); |
| |
| /** |
| * vfs_fsync - perform a fsync or fdatasync on a file |
| * @file: file to sync |
| * @datasync: only perform a fdatasync operation |
| * |
| * Write back data and metadata for @file to disk. If @datasync is |
| * set only metadata needed to access modified file data is written. |
| */ |
| int vfs_fsync(struct file *file, int datasync) |
| { |
| return vfs_fsync_range(file, 0, LLONG_MAX, datasync); |
| } |
| EXPORT_SYMBOL(vfs_fsync); |
| |
| static int do_fsync(unsigned int fd, int datasync) |
| { |
| struct fd f = fdget(fd); |
| int ret = -EBADF; |
| |
| if (f.file) { |
| ret = vfs_fsync(f.file, datasync); |
| fdput(f); |
| } |
| return ret; |
| } |
| |
| SYSCALL_DEFINE1(fsync, unsigned int, fd) |
| { |
| return do_fsync(fd, 0); |
| } |
| |
| SYSCALL_DEFINE1(fdatasync, unsigned int, fd) |
| { |
| return do_fsync(fd, 1); |
| } |
| |
| /* |
| * sys_sync_file_range() permits finely controlled syncing over a segment of |
| * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is |
| * zero then sys_sync_file_range() will operate from offset out to EOF. |
| * |
| * The flag bits are: |
| * |
| * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range |
| * before performing the write. |
| * |
| * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the |
| * range which are not presently under writeback. Note that this may block for |
| * significant periods due to exhaustion of disk request structures. |
| * |
| * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range |
| * after performing the write. |
| * |
| * Useful combinations of the flag bits are: |
| * |
| * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages |
| * in the range which were dirty on entry to sys_sync_file_range() are placed |
| * under writeout. This is a start-write-for-data-integrity operation. |
| * |
| * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which |
| * are not presently under writeout. This is an asynchronous flush-to-disk |
| * operation. Not suitable for data integrity operations. |
| * |
| * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for |
| * completion of writeout of all pages in the range. This will be used after an |
| * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait |
| * for that operation to complete and to return the result. |
| * |
| * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: |
| * a traditional sync() operation. This is a write-for-data-integrity operation |
| * which will ensure that all pages in the range which were dirty on entry to |
| * sys_sync_file_range() are committed to disk. |
| * |
| * |
| * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any |
| * I/O errors or ENOSPC conditions and will return those to the caller, after |
| * clearing the EIO and ENOSPC flags in the address_space. |
| * |
| * It should be noted that none of these operations write out the file's |
| * metadata. So unless the application is strictly performing overwrites of |
| * already-instantiated disk blocks, there are no guarantees here that the data |
| * will be available after a crash. |
| */ |
| int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes, |
| unsigned int flags) |
| { |
| int ret; |
| struct fd f; |
| struct address_space *mapping; |
| loff_t endbyte; /* inclusive */ |
| umode_t i_mode; |
| |
| ret = -EINVAL; |
| if (flags & ~VALID_FLAGS) |
| goto out; |
| |
| endbyte = offset + nbytes; |
| |
| if ((s64)offset < 0) |
| goto out; |
| if ((s64)endbyte < 0) |
| goto out; |
| if (endbyte < offset) |
| goto out; |
| |
| if (sizeof(pgoff_t) == 4) { |
| if (offset >= (0x100000000ULL << PAGE_SHIFT)) { |
| /* |
| * The range starts outside a 32 bit machine's |
| * pagecache addressing capabilities. Let it "succeed" |
| */ |
| ret = 0; |
| goto out; |
| } |
| if (endbyte >= (0x100000000ULL << PAGE_SHIFT)) { |
| /* |
| * Out to EOF |
| */ |
| nbytes = 0; |
| } |
| } |
| |
| if (nbytes == 0) |
| endbyte = LLONG_MAX; |
| else |
| endbyte--; /* inclusive */ |
| |
| ret = -EBADF; |
| f = fdget(fd); |
| if (!f.file) |
| goto out; |
| |
| i_mode = file_inode(f.file)->i_mode; |
| ret = -ESPIPE; |
| if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && |
| !S_ISLNK(i_mode)) |
| goto out_put; |
| |
| mapping = f.file->f_mapping; |
| ret = 0; |
| if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { |
| ret = file_fdatawait_range(f.file, offset, endbyte); |
| if (ret < 0) |
| goto out_put; |
| } |
| |
| if (flags & SYNC_FILE_RANGE_WRITE) { |
| ret = __filemap_fdatawrite_range(mapping, offset, endbyte, |
| WB_SYNC_NONE); |
| if (ret < 0) |
| goto out_put; |
| } |
| |
| if (flags & SYNC_FILE_RANGE_WAIT_AFTER) |
| ret = file_fdatawait_range(f.file, offset, endbyte); |
| |
| out_put: |
| fdput(f); |
| out: |
| return ret; |
| } |
| |
| SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes, |
| unsigned int, flags) |
| { |
| return ksys_sync_file_range(fd, offset, nbytes, flags); |
| } |
| |
| /* It would be nice if people remember that not all the world's an i386 |
| when they introduce new system calls */ |
| SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags, |
| loff_t, offset, loff_t, nbytes) |
| { |
| return ksys_sync_file_range(fd, offset, nbytes, flags); |
| } |