buffer.c

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/*
 *  linux/fs/hpfs/buffer.c
 *
 *  Mikulas Patocka ([email protected]), 1998-1999
 *
 *  general buffer i/o
 */
#include <linux/sched.h>
#include <linux/slab.h>
#include "hpfs_fn.h"

/* 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);

    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;
    }

    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]);
}