// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2010 Red Hat, Inc.
 * Copyright (c) 2016-2021 Christoph Hellwig.
 */
#include <linux/iomap.h>
#include "trace.h"

static inline void iomap_iter_reset_iomap(struct iomap_iter *iter)
{
        if (iter->iomap.flags & IOMAP_F_FOLIO_BATCH) {
                folio_batch_release(iter->fbatch);
                folio_batch_reinit(iter->fbatch);
                iter->iomap.flags &= ~IOMAP_F_FOLIO_BATCH;
        }

        iter->status = 0;
        memset(&iter->iomap, 0, sizeof(iter->iomap));
        memset(&iter->srcmap, 0, sizeof(iter->srcmap));
}

/* Advance the current iterator position and decrement the remaining length */
int iomap_iter_advance(struct iomap_iter *iter, u64 count)
{
        if (WARN_ON_ONCE(count > iomap_length(iter)))
                return -EIO;
        iter->pos += count;
        iter->len -= count;
        return 0;
}

static inline void iomap_iter_done(struct iomap_iter *iter)
{
        WARN_ON_ONCE(iter->iomap.offset > iter->pos);
        WARN_ON_ONCE(iter->iomap.length == 0);
        WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos);
        WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_STALE);

        iter->iter_start_pos = iter->pos;

        trace_iomap_iter_dstmap(iter->inode, &iter->iomap);
        if (iter->srcmap.type != IOMAP_HOLE)
                trace_iomap_iter_srcmap(iter->inode, &iter->srcmap);
}

/**
 * iomap_iter - iterate over a ranges in a file
 * @iter: iteration structue
 * @ops: iomap ops provided by the file system
 *
 * Iterate over filesystem-provided space mappings for the provided file range.
 *
 * This function handles cleanup of resources acquired for iteration when the
 * filesystem indicates there are no more space mappings, which means that this
 * function must be called in a loop that continues as long it returns a
 * positive value.  If 0 or a negative value is returned, the caller must not
 * return to the loop body.  Within a loop body, there are two ways to break out
 * of the loop body:  leave @iter.status unchanged, or set it to a negative
 * errno.
 */
int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)
{
        bool stale = iter->iomap.flags & IOMAP_F_STALE;
        ssize_t advanced;
        u64 olen;
        int ret;

        trace_iomap_iter(iter, ops, _RET_IP_);

        if (!iter->iomap.length)
                goto begin;

        /*
         * Calculate how far the iter was advanced and the original length bytes
         * for ->iomap_end().
         */
        advanced = iter->pos - iter->iter_start_pos;
        olen = iter->len + advanced;

        if (ops->iomap_end) {
                ret = ops->iomap_end(iter->inode, iter->iter_start_pos,
                                iomap_length_trim(iter, iter->iter_start_pos,
                                                  olen),
                                advanced, iter->flags, &iter->iomap);
                if (ret < 0 && !advanced)
                        return ret;
        }

        /* detect old return semantics where this would advance */
        if (WARN_ON_ONCE(iter->status > 0))
                iter->status = -EIO;

        /*
         * Use iter->len to determine whether to continue onto the next mapping.
         * Explicitly terminate on error status or if the current iter has not
         * advanced at all (i.e. no work was done for some reason) unless the
         * mapping has been marked stale and needs to be reprocessed.
         */
        if (iter->status < 0)
                ret = iter->status;
        else if (iter->len == 0 || (!advanced && !stale))
                ret = 0;
        else
                ret = 1;
        iomap_iter_reset_iomap(iter);
        if (ret <= 0)
                return ret;

begin:
        ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags,
                               &iter->iomap, &iter->srcmap);
        if (ret < 0)
                return ret;
        iomap_iter_done(iter);
        return 1;
}