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