/*
 *  linux/fs/hpfs/buffer.c
 *
 *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
 *
 *  general buffer i/o
 */
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include "hpfs_fn.h"

void hpfs_prefetch_sectors(struct super_block *s, unsigned secno, int n)
{
        struct buffer_head *bh;
        struct blk_plug plug;

        if (n <= 0 || unlikely(secno >= hpfs_sb(s)->sb_fs_size))
                return;

        bh = sb_find_get_block(s, secno);
        if (bh) {
                if (buffer_uptodate(bh)) {
                        brelse(bh);
                        return;
                }
                brelse(bh);
        };

        blk_start_plug(&plug);
        while (n > 0) {
                if (unlikely(secno >= hpfs_sb(s)->sb_fs_size))
                        break;
                sb_breadahead(s, secno);
                secno++;
                n--;
        }
        blk_finish_plug(&plug);
}

/* Map a sector into a buffer and return pointers to it and to the buffer. */

void *hpfs_map_sector(struct super_block *s, unsigned secno, struct buffer_head **bhp,
                 int ahead)
{
        struct buffer_head *bh;

        hpfs_lock_assert(s);

        hpfs_prefetch_sectors(s, secno, ahead);

        cond_resched();

        *bhp = bh = sb_bread(s, secno);
        if (bh != NULL)
                return bh->b_data;
        else {
                printk("HPFS: hpfs_map_sector: read error\n");
                return NULL;
        }
}

/* Like hpfs_map_sector but don't read anything */

void *hpfs_get_sector(struct super_block *s, unsigned secno, struct buffer_head **bhp)
{
        struct buffer_head *bh;
        /*return hpfs_map_sector(s, secno, bhp, 0);*/

        hpfs_lock_assert(s);

        cond_resched();

        if ((*bhp = bh = sb_getblk(s, secno)) != NULL) {
                if (!buffer_uptodate(bh)) wait_on_buffer(bh);
                set_buffer_uptodate(bh);
                return bh->b_data;
        } else {
                printk("HPFS: hpfs_get_sector: getblk failed\n");
                return NULL;
        }
}

/* Map 4 sectors into a 4buffer and return pointers to it and to the buffer. */

void *hpfs_map_4sectors(struct super_block *s, unsigned secno, struct quad_buffer_head *qbh,
                   int ahead)
{
        struct buffer_head *bh;
        char *data;

        hpfs_lock_assert(s);

        cond_resched();

        if (secno & 3) {
                printk("HPFS: hpfs_map_4sectors: unaligned read\n");
                return NULL;
        }

        hpfs_prefetch_sectors(s, secno, 4 + ahead);

        qbh->data = data = kmalloc(2048, GFP_NOFS);
        if (!data) {
                printk("HPFS: hpfs_map_4sectors: out of memory\n");
                goto bail;
        }

        qbh->bh[0] = bh = sb_bread(s, secno);
        if (!bh)
                goto bail0;
        memcpy(data, bh->b_data, 512);

        qbh->bh[1] = bh = sb_bread(s, secno + 1);
        if (!bh)
                goto bail1;
        memcpy(data + 512, bh->b_data, 512);

        qbh->bh[2] = bh = sb_bread(s, secno + 2);
        if (!bh)
                goto bail2;
        memcpy(data + 2 * 512, bh->b_data, 512);

        qbh->bh[3] = bh = sb_bread(s, secno + 3);
        if (!bh)
                goto bail3;
        memcpy(data + 3 * 512, bh->b_data, 512);

        return data;

 bail3:
        brelse(qbh->bh[2]);
 bail2:
        brelse(qbh->bh[1]);
 bail1:
        brelse(qbh->bh[0]);
 bail0:
        kfree(data);
        printk("HPFS: hpfs_map_4sectors: read error\n");
 bail:
        return NULL;
}

/* Don't read sectors */

void *hpfs_get_4sectors(struct super_block *s, unsigned secno,
                          struct quad_buffer_head *qbh)
{
        cond_resched();

        hpfs_lock_assert(s);

        if (secno & 3) {
                printk("HPFS: hpfs_get_4sectors: unaligned read\n");
                return NULL;
        }

        /*return hpfs_map_4sectors(s, secno, qbh, 0);*/
        if (!(qbh->data = kmalloc(2048, GFP_NOFS))) {
                printk("HPFS: hpfs_get_4sectors: out of memory\n");
                return NULL;
        }
        if (!(hpfs_get_sector(s, secno, &qbh->bh[0]))) goto bail0;
        if (!(hpfs_get_sector(s, secno + 1, &qbh->bh[1]))) goto bail1;
        if (!(hpfs_get_sector(s, secno + 2, &qbh->bh[2]))) goto bail2;
        if (!(hpfs_get_sector(s, secno + 3, &qbh->bh[3]))) goto bail3;
        memcpy(qbh->data, qbh->bh[0]->b_data, 512);
        memcpy(qbh->data + 512, qbh->bh[1]->b_data, 512);
        memcpy(qbh->data + 2*512, qbh->bh[2]->b_data, 512);
        memcpy(qbh->data + 3*512, qbh->bh[3]->b_data, 512);
        return qbh->data;

        bail3:  brelse(qbh->bh[2]);
        bail2:  brelse(qbh->bh[1]);
        bail1:  brelse(qbh->bh[0]);
        bail0:
        return NULL;
}
        

void hpfs_brelse4(struct quad_buffer_head *qbh)
{
        brelse(qbh->bh[3]);
        brelse(qbh->bh[2]);
        brelse(qbh->bh[1]);
        brelse(qbh->bh[0]);
        kfree(qbh->data);
}       

void hpfs_mark_4buffers_dirty(struct quad_buffer_head *qbh)
{
        memcpy(qbh->bh[0]->b_data, qbh->data, 512);
        memcpy(qbh->bh[1]->b_data, qbh->data + 512, 512);
        memcpy(qbh->bh[2]->b_data, qbh->data + 2 * 512, 512);
        memcpy(qbh->bh[3]->b_data, qbh->data + 3 * 512, 512);
        mark_buffer_dirty(qbh->bh[0]);
        mark_buffer_dirty(qbh->bh[1]);
        mark_buffer_dirty(qbh->bh[2]);
        mark_buffer_dirty(qbh->bh[3]);
}