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    /*
     *  linux/fs/hpfs/buffer.c
     *
     *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
     *
     *  general buffer i/o
     */
    
    #include "hpfs_fn.h"
    
    void hpfs_lock_creation(struct super_block *s)
    {
    #ifdef DEBUG_LOCKS
    	printk("lock creation\n");
    #endif
    	down(&hpfs_sb(s)->hpfs_creation_de);
    }
    
    void hpfs_unlock_creation(struct super_block *s)
    {
    #ifdef DEBUG_LOCKS
    	printk("unlock creation\n");
    #endif
    	up(&hpfs_sb(s)->hpfs_creation_de);
    }
    
    /* 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;
    
    	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);*/
    
    	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;
    
    	cond_resched();
    
    	if (secno & 3) {
    		printk("HPFS: hpfs_map_4sectors: unaligned read\n");
    		return NULL;
    	}
    
    
    	qbh->data = data = kmalloc(2048, GFP_NOFS);
    
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    	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();
    
    	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)
    {
    	PRINTK(("hpfs_mark_4buffers_dirty\n"));
    	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]);
    }