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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* NTFS block device I/O.
*
* Copyright (c) 2026 LG Electronics Co., Ltd.
*/
#include <linux/blkdev.h>
#include "ntfs.h"
/*
* ntfs_bdev_read - Read data directly from block device using bio
* @bdev: block device to read from
* @data: destination buffer
* @start: starting byte offset on the block device
* @size: number of bytes to read
*
* Reads @size bytes starting from byte offset @start directly from the block
* device using one or more BIOs. This function bypasses the page cache
* completely and performs synchronous I/O with REQ_META | REQ_SYNC flags set.
*
* The @start offset must be sector-aligned (512 bytes). If it is not aligned,
* the function will return -EINVAL.
*
* If the destination buffer @data is not a vmalloc address, it falls back
* to the more efficient bdev_rw_virt() helper.
*
* Return: 0 on success, negative error code on failure.
*/
int ntfs_bdev_read(struct block_device *bdev, char *data, loff_t start, size_t size)
{
unsigned int done = 0, added;
int error;
struct bio *bio;
enum req_op op;
sector_t sector = start >> SECTOR_SHIFT;
if (start & (SECTOR_SIZE - 1))
return -EINVAL;
op = REQ_OP_READ | REQ_META | REQ_SYNC;
if (!is_vmalloc_addr(data))
return bdev_rw_virt(bdev, sector, data, size, op);
bio = bio_alloc(bdev,
bio_max_segs(DIV_ROUND_UP(size, PAGE_SIZE)),
op, GFP_KERNEL);
bio->bi_iter.bi_sector = sector;
do {
added = bio_add_vmalloc_chunk(bio, data + done, size - done);
if (!added) {
struct bio *prev = bio;
bio = bio_alloc(prev->bi_bdev,
bio_max_segs(DIV_ROUND_UP(size - done, PAGE_SIZE)),
prev->bi_opf, GFP_KERNEL);
bio->bi_iter.bi_sector = bio_end_sector(prev);
bio_chain(prev, bio);
submit_bio(prev);
}
done += added;
} while (done < size);
error = submit_bio_wait(bio);
bio_put(bio);
if (op == REQ_OP_READ)
invalidate_kernel_vmap_range(data, size);
return error;
}
/*
* ntfs_bdev_write - Update block device contents via page cache
* @sb: super block of the mounted NTFS filesystem
* @buf: source buffer containing data to write
* @start: starting byte offset on the block device
* @size: number of bytes to write
*
* Writes @size bytes from @buf to the block device (sb->s_bdev) starting
* at byte offset @start. The write is performed entirely through the page
* cache of the block device's address space.
*/
int ntfs_bdev_write(struct super_block *sb, void *buf, loff_t start, size_t size)
{
pgoff_t idx, idx_end;
loff_t offset, end = start + size;
u32 from, to, buf_off = 0;
struct folio *folio;
idx = start >> PAGE_SHIFT;
idx_end = end >> PAGE_SHIFT;
from = start & ~PAGE_MASK;
if (idx == idx_end)
idx_end++;
for (; idx < idx_end; idx++, from = 0) {
folio = read_mapping_folio(sb->s_bdev->bd_mapping, idx, NULL);
if (IS_ERR(folio)) {
ntfs_error(sb, "Unable to read %ld page", idx);
return PTR_ERR(folio);
}
offset = (loff_t)idx << PAGE_SHIFT;
to = min_t(u32, end - offset, PAGE_SIZE);
memcpy_to_folio(folio, from, buf + buf_off, to);
buf_off += to;
folio_mark_uptodate(folio);
folio_mark_dirty(folio);
folio_put(folio);
}
return 0;
}
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