// SPDX-License-Identifier: GPL-2.0/* * High-level sync()-related operations */ #include <linux/blkdev.h>#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) /* * 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 = 0; 	/*	 * 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; 	/*	 * Do the filesystem syncing work.  For simple filesystems	 * writeback_inodes_sb(sb) just dirties buffers with inodes so we have	 * to submit I/O for these buffers via sync_blockdev().  This also	 * speeds up the wait == 1 case since in that case write_inode()	 * methods call sync_dirty_buffer() and thus effectively write one block	 * at a time.	 */	writeback_inodes_sb(sb, WB_REASON_SYNC);	if (sb->s_op->sync_fs) {		ret = sb->s_op->sync_fs(sb, 0);		if (ret)			return ret;	}	ret = sync_blockdev_nowait(sb->s_bdev);	if (ret)		return ret; 	sync_inodes_sb(sb);	if (sb->s_op->sync_fs) {		ret = sb->s_op->sync_fs(sb, 1);		if (ret)			return ret;	}	return sync_blockdev(sb->s_bdev);}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_iflags & SB_I_SKIP_SYNC) &&	    sb->s_op->sync_fs)		sb->s_op->sync_fs(sb, *(int *)arg);} /* * 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);	sync_bdevs(false);	sync_bdevs(true);} SYSCALL_DEFINE0(sync){	ksys_sync();	return 0;} static void do_sync_work(struct work_struct *work){	int nowait = 0;	int wait = 1; 	/*	 * Sync twice to reduce the possibility we skipped some inodes / pages	 * because they were temporarily locked	 */	iterate_supers(sync_inodes_one_sb, NULL);	iterate_supers(sync_fs_one_sb, &nowait);	sync_bdevs(false);	iterate_supers(sync_inodes_one_sb, NULL);	iterate_supers(sync_fs_one_sb, &wait);	sync_bdevs(false);	printk("Emergency Sync complete\n");	kfree(work);} void emergency_sync(void){	struct work_struct *work; 	work = kmalloc_obj(*work, GFP_ATOMIC);	if (work) {		INIT_WORK(work, do_sync_work);		schedule_work(work);	}} /* * sync a single super */SYSCALL_DEFINE1(syncfs, int, fd){	CLASS(fd, f)(fd);	struct super_block *sb;	int ret, ret2; 	if (fd_empty(f))		return -EBADF;	sb = fd_file(f)->f_path.dentry->d_sb; 	down_read(&sb->s_umount);	ret = sync_filesystem(sb);	up_read(&sb->s_umount); 	ret2 = errseq_check_and_advance(&sb->s_wb_err, &fd_file(f)->f_sb_err); 	return ret ? ret : ret2;} /** * 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)		sync_lazytime(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){	CLASS(fd, f)(fd); 	if (fd_empty(f))		return -EBADF; 	return vfs_fsync(fd_file(f), datasync);} SYSCALL_DEFINE1(fsync, unsigned int, fd){	return do_fsync(fd, 0);} SYSCALL_DEFINE1(fdatasync, unsigned int, fd){	return do_fsync(fd, 1);} int sync_file_range(struct file *file, loff_t offset, loff_t nbytes,		    unsigned int flags){	int ret;	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 */ 	i_mode = file_inode(file)->i_mode;	ret = -ESPIPE;	if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&			!S_ISLNK(i_mode))		goto out; 	mapping = file->f_mapping;	ret = 0;	if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {		ret = file_fdatawait_range(file, offset, endbyte);		if (ret < 0)			goto out;	} 	if (flags & SYNC_FILE_RANGE_WRITE) {		if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) ==			     SYNC_FILE_RANGE_WRITE_AND_WAIT)			ret = filemap_fdatawrite_range(mapping, offset,					endbyte);		else			ret = filemap_flush_range(mapping, offset, endbyte);		if (ret < 0)			goto out;	} 	if (flags & SYNC_FILE_RANGE_WAIT_AFTER)		ret = file_fdatawait_range(file, offset, endbyte); out:	return ret;} /* * ksys_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 ksys_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 ksys_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.k.a. SYNC_FILE_RANGE_WRITE_AND_WAIT): * 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 * ksys_sync_file_range() are written to disk.  It should be noted that disk * caches are not flushed by this call, so there are no guarantees here that the * data will be available on disk after a crash. * * * 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){	CLASS(fd, f)(fd); 	if (fd_empty(f))		return -EBADF; 	return sync_file_range(fd_file(f), offset, nbytes, flags);} 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);} #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_SYNC_FILE_RANGE)COMPAT_SYSCALL_DEFINE6(sync_file_range, int, fd, compat_arg_u64_dual(offset),		       compat_arg_u64_dual(nbytes), unsigned int, flags){	return ksys_sync_file_range(fd, compat_arg_u64_glue(offset),				    compat_arg_u64_glue(nbytes), flags);}#endif /* 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);}