patch-2.2.18 linux/fs/adfs/map.c
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- Lines: 361
- Date:
Fri Sep 15 23:24:41 2000
- Orig file:
v2.2.17/fs/adfs/map.c
- Orig date:
Fri Apr 21 12:46:40 2000
diff -u --new-file --recursive --exclude-from /usr/src/exclude v2.2.17/fs/adfs/map.c linux/fs/adfs/map.c
@@ -1,108 +1,288 @@
/*
* linux/fs/adfs/map.c
*
- * Copyright (C) 1997 Russell King
+ * Copyright (C) 1997-1999 Russell King
*/
-
+#include <linux/version.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/adfs_fs.h>
-static inline unsigned int
-adfs_convert_map_to_sector (const struct super_block *sb, unsigned int mapoff)
-{
- if (sb->u.adfs_sb.s_map2blk >= 0)
- mapoff <<= sb->u.adfs_sb.s_map2blk;
- else
- mapoff >>= -sb->u.adfs_sb.s_map2blk;
- return mapoff;
-}
+#include <asm/spinlock.h>
-static inline unsigned int
-adfs_convert_sector_to_map (const struct super_block *sb, unsigned int secoff)
-{
- if (sb->u.adfs_sb.s_map2blk >= 0)
- secoff >>= sb->u.adfs_sb.s_map2blk;
- else
- secoff <<= -sb->u.adfs_sb.s_map2blk;
- return secoff;
-}
+#include "adfs.h"
-static int lookup_zone (struct super_block *sb, int zone, int frag_id, int *offset)
-{
- unsigned int mapptr, idlen, mapsize;
- unsigned long *map;
+/*
+ * For the future...
+ */
+static rwlock_t adfs_map_lock;
- map = ((unsigned long *)sb->u.adfs_sb.s_map[zone]->b_data) + 1;
- zone =
- mapptr = zone == 0 ? (ADFS_DR_SIZE << 3) : 0;
- idlen = sb->u.adfs_sb.s_idlen;
- mapsize = sb->u.adfs_sb.s_zonesize;
+/*
+ * 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 v1, v2;
- unsigned int start;
+ unsigned long frag;
- v1 = map[mapptr>>5];
- v2 = map[(mapptr>>5)+1];
+ /*
+ * get fragment id
+ */
+ {
+ unsigned long v2;
+ unsigned int tmp;
- v1 = (v1 >> (mapptr & 31)) | (v2 << (32 - (mapptr & 31)));
- start = mapptr;
- mapptr += idlen;
+ tmp = start >> 5;
+
+ frag = le32_to_cpu(map[tmp]);
+ v2 = le32_to_cpu(map[tmp + 1]);
+
+ tmp = start & 31;
- v2 = map[mapptr >> 5] >> (mapptr & 31);
- if (!v2) {
- mapptr = (mapptr + 32) & ~31;
- for (; (v2 = map[mapptr >> 5]) == 0 && mapptr < mapsize; mapptr += 32);
+ frag = (frag >> tmp) | (v2 << (32 - tmp));
+
+ frag &= idmask;
}
- for (; (v2 & 255) == 0; v2 >>= 8, mapptr += 8);
- for (; (v2 & 1) == 0; v2 >>= 1, mapptr += 1);
- mapptr += 1;
-
- if ((v1 & ((1 << idlen) - 1)) == frag_id) {
- int length = mapptr - start;
- if (*offset >= length)
- *offset -= length;
- else
- return start + *offset - zone;
+
+ 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;
}
-int adfs_map_lookup (struct super_block *sb, int frag_id, int offset)
+/*
+ * 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)
{
- unsigned int start_zone, zone, max_zone, mapoff, secoff;
+ 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 unsigned int idmask = (1 << frag_idlen) - 1;
+ unsigned long *map = (unsigned long *)dm->dm_bh->b_data;
+ unsigned int start = 8, mapptr;
+ unsigned long frag;
+ unsigned long total = 0;
+
+ /*
+ * get fragment id
+ */
+ {
+ unsigned long v2;
+ unsigned int tmp;
+
+ tmp = start >> 5;
- zone = start_zone = frag_id / sb->u.adfs_sb.s_ids_per_zone;
- max_zone = sb->u.adfs_sb.s_map_size;
+ frag = le32_to_cpu(map[tmp]);
+ v2 = le32_to_cpu(map[tmp + 1]);
- if (start_zone >= max_zone) {
- adfs_error (sb, "adfs_map_lookup", "fragment %X is invalid (zone = %d, max = %d)",
- frag_id, start_zone, max_zone);
- return 0;
+ tmp = start & 31;
+
+ frag = (frag >> tmp) | (v2 << (32 - tmp));
+
+ frag &= idmask;
}
- /* Convert sector offset to map offset */
- mapoff = adfs_convert_sector_to_map (sb, offset);
- /* Calculate sector offset into map block */
- secoff = offset - adfs_convert_map_to_sector (sb, mapoff);
+ /*
+ * If the freelink is null, then no free fragments
+ * exist in this zone.
+ */
+ if (frag == 0)
+ return 0;
do {
- int result = lookup_zone (sb, zone, frag_id, &mapoff);
+ start += frag;
+
+ /*
+ * get fragment id
+ */
+ {
+ unsigned long v2;
+ unsigned int tmp;
+
+ tmp = start >> 5;
+
+ frag = le32_to_cpu(map[tmp]);
+ v2 = le32_to_cpu(map[tmp + 1]);
+
+ tmp = start & 31;
- if (result != -1) {
- result += zone ? (zone * sb->u.adfs_sb.s_zonesize) - (ADFS_DR_SIZE << 3): 0;
- return adfs_convert_map_to_sector (sb, result) + secoff;
+ frag = (frag >> tmp) | (v2 << (32 - tmp));
+
+ frag &= 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);
}
- zone ++;
- if (zone >= max_zone)
- zone = 0;
+ 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;
+}
+
+static int
+scan_map(struct adfs_sb_info *asb, unsigned int zone,
+ const unsigned int frag_id, unsigned int mapoff)
+{
+ const unsigned int idlen = asb->s_idlen;
+ struct adfs_discmap *dm, *dm_end;
+ int result;
+
+ dm = asb->s_map + zone;
+ zone = asb->s_map_size;
+ dm_end = asb->s_map + zone;
+
+ do {
+ result = lookup_zone(dm, idlen, frag_id, &mapoff);
+
+ if (result != -1)
+ goto found;
+
+ dm ++;
+ if (dm == dm_end)
+ dm = asb->s_map;
+ } while (--zone > 0);
+
+ return -1;
+found:
+ result -= dm->dm_startbit;
+ result += dm->dm_startblk;
+
+ return result;
+}
+
+/*
+ * calculate the amount of free blocks in the map.
+ *
+ * n=1
+ * total_free = E(free_in_zone_n)
+ * nzones
+ */
+unsigned int
+adfs_map_free(struct super_block *sb)
+{
+ struct adfs_sb_info *asb = &sb->u.adfs_sb;
+ struct adfs_discmap *dm;
+ unsigned int total = 0;
+ unsigned int zone;
+
+ dm = asb->s_map;
+ zone = asb->s_map_size;
+
+ do {
+ total += scan_free_map(asb, dm++);
+ } while (--zone > 0);
+
+ return signed_asl(total, asb->s_map2blk);
+}
- } while (zone != start_zone);
+int adfs_map_lookup (struct super_block *sb, int frag_id, int offset)
+{
+ struct adfs_sb_info *asb = &sb->u.adfs_sb;
+ unsigned int zone, mapoff;
+ int result;
+
+ /*
+ * map & root fragment is special - it starts in the center of the
+ * disk. The other fragments start at zone (frag / ids_per_zone)
+ */
+ if (frag_id == ADFS_ROOT_FRAG)
+ zone = asb->s_map_size >> 1;
+ else
+ zone = frag_id / asb->s_ids_per_zone;
+
+ if (zone >= asb->s_map_size)
+ goto bad_fragment;
+
+ /* Convert sector offset to map offset */
+ mapoff = signed_asl(offset, -asb->s_map2blk);
+
+ read_lock(&adfs_map_lock);
+ result = scan_map(asb, zone, frag_id, mapoff);
+ read_unlock(&adfs_map_lock);
+
+ if (result > 0) {
+ unsigned int secoff;
+
+ /* Calculate sector offset into map block */
+ secoff = offset - signed_asl(mapoff, asb->s_map2blk);
+ return secoff + signed_asl(result, asb->s_map2blk);
+ }
- adfs_error (sb, "adfs_map_lookup", "fragment %X at offset %d not found in map (start zone %d)",
- frag_id, offset, start_zone);
+ adfs_error(sb, "fragment %04X at offset %d not found in map",
+ frag_id, offset);
+ return 0;
+
+bad_fragment:
+ adfs_error(sb, "fragment %X is invalid (zone = %d, max = %d)",
+ frag_id, zone, asb->s_map_size);
return 0;
}
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