// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2017 Red Hat, Inc.
 * Copyright (c) 2018-2021 Christoph Hellwig.
 */
#include <linux/iomap.h>
#include <linux/pagemap.h>

static int iomap_seek_hole_iter(struct iomap_iter *iter,
                loff_t *hole_pos)
{
        loff_t length = iomap_length(iter);

        switch (iter->iomap.type) {
        case IOMAP_UNWRITTEN:
                *hole_pos = mapping_seek_hole_data(iter->inode->i_mapping,
                                iter->pos, iter->pos + length, SEEK_HOLE);
                if (*hole_pos == iter->pos + length)
                        return iomap_iter_advance(iter, length);
                return 0;
        case IOMAP_HOLE:
                *hole_pos = iter->pos;
                return 0;
        default:
                return iomap_iter_advance(iter, length);
        }
}

loff_t
iomap_seek_hole(struct inode *inode, loff_t pos, const struct iomap_ops *ops)
{
        loff_t size = i_size_read(inode);
        struct iomap_iter iter = {
                .inode  = inode,
                .pos    = pos,
                .flags  = IOMAP_REPORT,
        };
        int ret;

        /* Nothing to be found before or beyond the end of the file. */
        if (pos < 0 || pos >= size)
                return -ENXIO;

        iter.len = size - pos;
        while ((ret = iomap_iter(&iter, ops)) > 0)
                iter.status = iomap_seek_hole_iter(&iter, &pos);
        if (ret < 0)
                return ret;
        if (iter.len) /* found hole before EOF */
                return pos;
        return size;
}
EXPORT_SYMBOL_GPL(iomap_seek_hole);

static int iomap_seek_data_iter(struct iomap_iter *iter,
                loff_t *hole_pos)
{
        loff_t length = iomap_length(iter);

        switch (iter->iomap.type) {
        case IOMAP_HOLE:
                return iomap_iter_advance(iter, length);
        case IOMAP_UNWRITTEN:
                *hole_pos = mapping_seek_hole_data(iter->inode->i_mapping,
                                iter->pos, iter->pos + length, SEEK_DATA);
                if (*hole_pos < 0)
                        return iomap_iter_advance(iter, length);
                return 0;
        default:
                *hole_pos = iter->pos;
                return 0;
        }
}

loff_t
iomap_seek_data(struct inode *inode, loff_t pos, const struct iomap_ops *ops)
{
        loff_t size = i_size_read(inode);
        struct iomap_iter iter = {
                .inode  = inode,
                .pos    = pos,
                .flags  = IOMAP_REPORT,
        };
        int ret;

        /* Nothing to be found before or beyond the end of the file. */
        if (pos < 0 || pos >= size)
                return -ENXIO;

        iter.len = size - pos;
        while ((ret = iomap_iter(&iter, ops)) > 0)
                iter.status = iomap_seek_data_iter(&iter, &pos);
        if (ret < 0)
                return ret;
        if (iter.len) /* found data before EOF */
                return pos;
        /* We've reached the end of the file without finding data */
        return -ENXIO;
}
EXPORT_SYMBOL_GPL(iomap_seek_data);