fs/ext4/fsync.c

Source file repositories/reference/linux-study-clean/fs/ext4/fsync.c

File Facts

System
Linux kernel
Corpus path
fs/ext4/fsync.c
Extension
.c
Size
5072 bytes
Lines
191
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/ext4/fsync.c
 *
 *  Copyright (C) 1993  Stephen Tweedie (sct@redhat.com)
 *  from
 *  Copyright (C) 1992  Remy Card (card@masi.ibp.fr)
 *                      Laboratoire MASI - Institut Blaise Pascal
 *                      Universite Pierre et Marie Curie (Paris VI)
 *  from
 *  linux/fs/minix/truncate.c   Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  ext4fs fsync primitive
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 *
 *  Removed unnecessary code duplication for little endian machines
 *  and excessive __inline__s.
 *        Andi Kleen, 1997
 *
 * Major simplications and cleanup - we only need to do the metadata, because
 * we can depend on generic_block_fdatasync() to sync the data blocks.
 */

#include <linux/time.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/buffer_head.h>

#include "ext4.h"
#include "ext4_jbd2.h"

#include <trace/events/ext4.h>

/*
 * If we're not journaling and this is a just-created file, we have to
 * sync our parent directory (if it was freshly created) since
 * otherwise it will only be written by writeback, leaving a huge
 * window during which a crash may lose the file.  This may apply for
 * the parent directory's parent as well, and so on recursively, if
 * they are also freshly created.
 */
static int ext4_sync_parent(struct inode *inode)
{
	struct dentry *dentry, *next;
	int ret = 0;

	if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY))
		return 0;
	dentry = d_find_any_alias(inode);
	if (!dentry)
		return 0;
	while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {
		ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);

		next = dget_parent(dentry);
		dput(dentry);
		dentry = next;
		inode = dentry->d_inode;

		/*
		 * The directory inode may have gone through rmdir by now. But
		 * the inode itself and its blocks are still allocated (we hold
		 * a reference to the inode via its dentry), so it didn't go
		 * through ext4_evict_inode()) and so we are safe to flush
		 * metadata blocks and the inode.
		 */
		ret = mmb_sync(&EXT4_I(inode)->i_metadata_bhs);
		if (ret)
			break;
		ret = sync_inode_metadata(inode, 1);
		if (ret)
			break;
	}
	dput(dentry);
	return ret;
}

static int ext4_fsync_nojournal(struct file *file, loff_t start, loff_t end,
				int datasync, bool *needs_barrier)
{
	struct inode *inode = file->f_inode;
	struct writeback_control wbc = {
		.sync_mode = WB_SYNC_ALL,
		.nr_to_write = 0,
	};
	int ret;

Annotation

Implementation Notes