path: root/fs/ntfs/file.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * NTFS kernel file operations.
 *
 * Copyright (c) 2001-2015 Anton Altaparmakov and Tuxera Inc.
 * Copyright (c) 2025 LG Electronics Co., Ltd.
 */

#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/fs.h>
#include <linux/iomap.h>
#include <linux/uio.h>
#include <linux/posix_acl.h>
#include <linux/posix_acl_xattr.h>
#include <linux/compat.h>
#include <linux/falloc.h>

#include "lcnalloc.h"
#include "ntfs.h"
#include "reparse.h"
#include "ea.h"
#include "iomap.h"
#include "bitmap.h"

#include <linux/filelock.h>

/*
 * ntfs_file_open - called when an inode is about to be opened
 * @vi:		inode to be opened
 * @filp:	file structure describing the inode
 *
 * Limit file size to the page cache limit on architectures where unsigned long
 * is 32-bits. This is the most we can do for now without overflowing the page
 * cache page index. Doing it this way means we don't run into problems because
 * of existing too large files. It would be better to allow the user to read
 * the beginning of the file but I doubt very much anyone is going to hit this
 * check on a 32-bit architecture, so there is no point in adding the extra
 * complexity required to support this.
 *
 * On 64-bit architectures, the check is hopefully optimized away by the
 * compiler.
 *
 * After the check passes, just call generic_file_open() to do its work.
 */
static int ntfs_file_open(struct inode *vi, struct file *filp)
{
	struct ntfs_inode *ni = NTFS_I(vi);

	if (NVolShutdown(ni->vol))
		return -EIO;

	if (sizeof(unsigned long) < 8) {
		if (i_size_read(vi) > MAX_LFS_FILESIZE)
			return -EOVERFLOW;
	}

	filp->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;

	return generic_file_open(vi, filp);
}

/*
 * Trim preallocated space on file release.
 *
 * When the preallo_size mount option is set (default 64KB), writes extend
 * allocated_size and runlist in units of preallocated size to reduce
 * runlist merge overhead for small writes. This can leave
 * allocated_size > data_size if not all preallocated space is used.
 *
 * We perform the trim here because ->release() is called only when
 * the file is no longer open. At this point, no further writes can occur,
 * so it is safe to reclaim the unused preallocated space.
 *
 * Returns 0 on success, or negative error on failure.
 */
static int ntfs_trim_prealloc(struct inode *vi)
{
	struct ntfs_inode *ni = NTFS_I(vi);
	struct ntfs_volume *vol = ni->vol;
	struct runlist_element *rl;
	s64 aligned_data_size;
	s64 vcn_ds, vcn_tr;
	ssize_t rc;
	int err = 0;

	inode_lock(vi);
	mutex_lock(&ni->mrec_lock);
	down_write(&ni->runlist.lock);

	aligned_data_size = round_up(ni->data_size, vol->cluster_size);
	if (aligned_data_size >= ni->allocated_size)
		goto out_unlock;

	vcn_ds = ntfs_bytes_to_cluster(vol, aligned_data_size);
	vcn_tr = -1;
	rc = ni->runlist.count - 2;
	rl = ni->runlist.rl;

	while (rc >= 0 && rl[rc].lcn == LCN_HOLE && vcn_ds <= rl[rc].vcn) {
		vcn_tr = rl[rc].vcn;
		rc--;
	}

	if (vcn_tr >= 0) {
		err = ntfs_rl_truncate_nolock(vol, &ni->runlist, vcn_tr);
		if (err) {
			kvfree(ni->runlist.rl);
			ni->runlist.rl = NULL;
			ntfs_error(vol->sb, "Preallocated block rollback failed");
		} else {
			ni->allocated_size = ntfs_cluster_to_bytes(vol, vcn_tr);
			err = ntfs_attr_update_mapping_pairs(ni, 0);
			if (err)
				ntfs_error(vol->sb,
					   "Failed to rollback mapping pairs for prealloc");
		}
	}

out_unlock:
	up_