fs/hpfs/buffer.c

   1 /*
   2  *  linux/fs/hpfs/buffer.c
   3  *
   4  *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
   5  *
   6  *  general buffer i/o
   7  */
   8 #include <linux/sched.h>
   9 #include <linux/slab.h>
  10 #include <linux/blkdev.h>
  11 #include "hpfs_fn.h"
  12
  13 void hpfs_prefetch_sectors(struct super_block *s, unsigned secno, int n)
  14 {
  15         struct buffer_head *bh;
  16         struct blk_plug plug;
  17
  18         if (n <= 0 || unlikely(secno >= hpfs_sb(s)->sb_fs_size))
  19                 return;
  20
  21         bh = sb_find_get_block(s, secno);
  22         if (bh) {
  23                 if (buffer_uptodate(bh)) {
  24                         brelse(bh);
  25                         return;
  26                 }
  27                 brelse(bh);
  28         };
  29
  30         blk_start_plug(&plug);
  31         while (n > 0) {
  32                 if (unlikely(secno >= hpfs_sb(s)->sb_fs_size))
  33                         break;
  34                 sb_breadahead(s, secno);
  35                 secno++;
  36                 n--;
  37         }
  38         blk_finish_plug(&plug);
  39 }
  40
  41 /* Map a sector into a buffer and return pointers to it and to the buffer. */
  42
  43 void *hpfs_map_sector(struct super_block *s, unsigned secno, struct buffer_head **bhp,
  44                  int ahead)
  45 {
  46         struct buffer_head *bh;
  47
  48         hpfs_lock_assert(s);
  49
  50         hpfs_prefetch_sectors(s, secno, ahead);
  51
  52         cond_resched();
  53
  54         *bhp = bh = sb_bread(s, secno);
  55         if (bh != NULL)
  56                 return bh->b_data;
  57         else {
  58                 printk("HPFS: hpfs_map_sector: read error\n");
  59                 return NULL;
  60         }
  61 }
  62
  63 /* Like hpfs_map_sector but don't read anything */
  64
  65 void *hpfs_get_sector(struct super_block *s, unsigned secno, struct buffer_head **bhp)
  66 {
  67         struct buffer_head *bh;
  68         /*return hpfs_map_sector(s, secno, bhp, 0);*/
  69
  70         hpfs_lock_assert(s);
  71
  72         cond_resched();
  73
  74         if ((*bhp = bh = sb_getblk(s, secno)) != NULL) {
  75                 if (!buffer_uptodate(bh)) wait_on_buffer(bh);
  76                 set_buffer_uptodate(bh);
  77                 return bh->b_data;
  78         } else {
  79                 printk("HPFS: hpfs_get_sector: getblk failed\n");
  80                 return NULL;
  81         }
  82 }
  83
  84 /* Map 4 sectors into a 4buffer and return pointers to it and to the buffer. */
  85
  86 void *hpfs_map_4sectors(struct super_block *s, unsigned secno, struct quad_buffer_head *qbh,
  87                    int ahead)
  88 {
  89         char *data;
  90
  91         hpfs_lock_assert(s);
  92
  93         cond_resched();
  94
  95         if (secno & 3) {
  96                 printk("HPFS: hpfs_map_4sectors: unaligned read\n");
  97                 return NULL;
  98         }
  99
 100         hpfs_prefetch_sectors(s, secno, 4 + ahead);
 101
 102         if (!(qbh->bh[0] = sb_bread(s, secno + 0))) goto bail0;
 103         if (!(qbh->bh[1] = sb_bread(s, secno + 1))) goto bail1;
 104         if (!(qbh->bh[2] = sb_bread(s, secno + 2))) goto bail2;
 105         if (!(qbh->bh[3] = sb_bread(s, secno + 3))) goto bail3;
 106
 107         if (likely(qbh->bh[1]->b_data == qbh->bh[0]->b_data + 1 * 512) &&
 108             likely(qbh->bh[2]->b_data == qbh->bh[0]->b_data + 2 * 512) &&
 109             likely(qbh->bh[3]->b_data == qbh->bh[0]->b_data + 3 * 512)) {
 110                 return qbh->data = qbh->bh[0]->b_data;
 111         }
 112
 113         qbh->data = data = kmalloc(2048, GFP_NOFS);
 114         if (!data) {
 115                 printk("HPFS: hpfs_map_4sectors: out of memory\n");
 116                 goto bail4;
 117         }
 118
 119         memcpy(data + 0 * 512, qbh->bh[0]->b_data, 512);
 120         memcpy(data + 1 * 512, qbh->bh[1]->b_data, 512);
 121         memcpy(data + 2 * 512, qbh->bh[2]->b_data, 512);
 122         memcpy(data + 3 * 512, qbh->bh[3]->b_data, 512);
 123
 124         return data;
 125
 126  bail4:
 127         brelse(qbh->bh[3]);
 128  bail3:
 129         brelse(qbh->bh[2]);
 130  bail2:
 131         brelse(qbh->bh[1]);
 132  bail1:
 133         brelse(qbh->bh[0]);
 134  bail0:
 135         return NULL;
 136 }
 137
 138 /* Don't read sectors */
 139
 140 void *hpfs_get_4sectors(struct super_block *s, unsigned secno,
 141                           struct quad_buffer_head *qbh)
 142 {
 143         cond_resched();
 144
 145         hpfs_lock_assert(s);
 146
 147         if (secno & 3) {
 148                 printk("HPFS: hpfs_get_4sectors: unaligned read\n");
 149                 return NULL;
 150         }
 151
 152         if (!hpfs_get_sector(s, secno + 0, &qbh->bh[0])) goto bail0;
 153         if (!hpfs_get_sector(s, secno + 1, &qbh->bh[1])) goto bail1;
 154         if (!hpfs_get_sector(s, secno + 2, &qbh->bh[2])) goto bail2;
 155         if (!hpfs_get_sector(s, secno + 3, &qbh->bh[3])) goto bail3;
 156
 157         if (likely(qbh->bh[1]->b_data == qbh->bh[0]->b_data + 1 * 512) &&
 158             likely(qbh->bh[2]->b_data == qbh->bh[0]->b_data + 2 * 512) &&
 159             likely(qbh->bh[3]->b_data == qbh->bh[0]->b_data + 3 * 512)) {
 160                 return qbh->data = qbh->bh[0]->b_data;
 161         }
 162
 163         if (!(qbh->data = kmalloc(2048, GFP_NOFS))) {
 164                 printk("HPFS: hpfs_get_4sectors: out of memory\n");
 165                 goto bail4;
 166         }
 167         return qbh->data;
 168
 169 bail4:
 170         brelse(qbh->bh[3]);
 171 bail3:
 172         brelse(qbh->bh[2]);
 173 bail2:
 174         brelse(qbh->bh[1]);
 175 bail1:
 176         brelse(qbh->bh[0]);
 177 bail0:
 178         return NULL;
 179 }
 180
 181
 182 void hpfs_brelse4(struct quad_buffer_head *qbh)
 183 {
 184         if (unlikely(qbh->data != qbh->bh[0]->b_data))
 185                 kfree(qbh->data);
 186         brelse(qbh->bh[0]);
 187         brelse(qbh->bh[1]);
 188         brelse(qbh->bh[2]);
 189         brelse(qbh->bh[3]);
 190 }
 191
 192 void hpfs_mark_4buffers_dirty(struct quad_buffer_head *qbh)
 193 {
 194         if (unlikely(qbh->data != qbh->bh[0]->b_data)) {
 195                 memcpy(qbh->bh[0]->b_data, qbh->data + 0 * 512, 512);
 196                 memcpy(qbh->bh[1]->b_data, qbh->data + 1 * 512, 512);
 197                 memcpy(qbh->bh[2]->b_data, qbh->data + 2 * 512, 512);
 198                 memcpy(qbh->bh[3]->b_data, qbh->data + 3 * 512, 512);
 199         }
 200         mark_buffer_dirty(qbh->bh[0]);
 201         mark_buffer_dirty(qbh->bh[1]);
 202         mark_buffer_dirty(qbh->bh[2]);
 203         mark_buffer_dirty(qbh->bh[3]);
 204 }