/*
* Scan the free space map, for this zone, calculating the total
* number of map bits in each free space fragment.
*
* Note: idmask is limited to 15 bits [3.2]
*/
static unsigned int
scan_free_map(struct adfs_sb_info *asb, struct adfs_discmap *dm)
{
const unsigned int mapsize = dm->dm_endbit + 32;
const unsigned int idlen = asb->s_idlen;
const unsigned int frag_idlen = idlen <= 15 ? idlen : 15;
const u32 idmask = (1 << frag_idlen) - 1;
unsigned char *map = dm->dm_bh->b_data;
unsigned int start = 8, mapptr;
u32 frag;
unsigned long total = 0;
/*
* get fragment id
*/
frag = GET_FRAG_ID(map, start, idmask);
/*
* If the freelink is null, then no free fragments
* exist in this zone.
*/
if (frag == 0)
return 0;
do {
start += frag;
/*
* get fragment id
*/
frag = GET_FRAG_ID(map, start, idmask);
mapptr = start + idlen;
/*
* find end of fragment
*/
{
__le32 *_map = (__le32 *)map;
u32 v = le32_to_cpu(_map[mapptr >> 5]) >> (mapptr & 31);
while (v == 0) {
mapptr = (mapptr & ~31) + 32;
if (mapptr >= mapsize)
goto error;
v = le32_to_cpu(_map[mapptr >> 5]);
}
mapptr += 1 + ffz(~v);
}
total += mapptr - start;
} while (frag >= idlen + 1);
if (frag != 0)
printk(KERN_ERR "adfs: undersized free fragment\n");
return total;
error:
printk(KERN_ERR "adfs: oversized free fragment\n");
return 0;
}
/*
* return the map bit offset of the fragment frag_id in the zone dm.
* Note that the loop is optimised for best asm code - look at the
* output of:
* gcc -D__KERNEL__ -O2 -I../../include -o - -S map.c
*/
static int
lookup_zone(const struct adfs_discmap *dm, const unsigned int idlen,
const unsigned int frag_id, unsigned int *offset)
{
const unsigned int mapsize = dm->dm_endbit;
const u32 idmask = (1 << idlen) - 1;
unsigned char *map = dm->dm_bh->b_data + 4;
unsigned int start = dm->dm_startbit;
unsigned int mapptr;
u32 frag;
do {
frag = GET_FRAG_ID(map, start, idmask);
mapptr = start + idlen;
/*
* find end of fragment
*/
{
u32 v, *_map = (u32 *)map;
v = le32_to_cpu(_map[mapptr >> 5]) >> (mapptr & 31);
while (v == 0) {
mapptr = (mapptr & ~31) + 32;
if (mapptr >= mapsize)
goto error;
v = le32_to_cpu(_map[mapptr >> 5]);
}
mapptr += 1 + ffz(~v);
}
if (frag == frag_id)
goto found;
again:
start = mapptr;
} while (mapptr < mapsize);
return -1;
error:
printk(KERN_ERR "adfs: oversized fragment 0x%x at 0x%x-0x%x\n",
frag, start, mapptr);
return -1;
found:
{
int length = mapptr - start;
if (*offset >= length) {
*offset -= length;
goto again;
}
}
return start + *offset;
}
/*
* return the map bit offset of the fragment frag_id in
* the zone dm.
* Note that the loop is optimised for best asm code -
* look at the output of:
* gcc -D__KERNEL__ -O2 -I../../include -o - -S map.c
*/
static int
lookup_zone(const struct adfs_discmap *dm, const unsigned int idlen,
const unsigned int frag_id, unsigned int *offset)
{
const unsigned int mapsize = dm->dm_endbit;
const unsigned int idmask = (1 << idlen) - 1;
unsigned long *map = ((unsigned long *)dm->dm_bh->b_data) + 1;
unsigned int start = dm->dm_startbit;
unsigned int mapptr;
do {
unsigned long frag;
frag = GET_FRAG_ID(map, start, idmask);
mapptr = start + idlen;
/*
* find end of fragment
*/
{
unsigned long v2;
while ((v2 = map[mapptr >> 5] >> (mapptr & 31)) == 0) {
mapptr = (mapptr & ~31) + 32;
if (mapptr >= mapsize)
goto error;
}
mapptr += 1 + ffz(~v2);
}
if (frag == frag_id)
goto found;
again:
start = mapptr;
} while (mapptr < mapsize);
error:
return -1;
found:
{
int length = mapptr - start;
if (*offset >= length) {
*offset -= length;
goto again;
}
}
return start + *offset;
}
