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[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [fs/] [adfs/] [map.c] - Blame information for rev 1765

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/*
 *  linux/fs/adfs/map.c
 *
 *  Copyright (C) 1997-1999 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/version.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/adfs_fs.h>
#include <linux/spinlock.h>
 
#include "adfs.h"
 
/*
 * For the future...
 */
static rwlock_t adfs_map_lock;
 
#define GET_FRAG_ID(_map,_start,_idmask)                                \
        ({                                                              \
                unsigned long _v2, _frag;                               \
                unsigned int _tmp;                                      \
                _tmp = _start >> 5;                                     \
                _frag = le32_to_cpu(_map[_tmp]);                        \
                _v2   = le32_to_cpu(_map[_tmp + 1]);                    \
                _tmp = start & 31;                                      \
                _frag = (_frag >> _tmp) | (_v2 << (32 - _tmp));         \
                _frag & _idmask;                                        \
        })
 
/*
 * 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;
}
 
/*
 * 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 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
         */
        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
                 */
                {
                        unsigned long v2;
 
                        while ((v2 = map[mapptr >> 5] >> (mapptr & 31)) == 0) {
                                mapptr = (mapptr & ~31) + 32;
                                if (mapptr >= mapsize)
                                        goto error;
                        }
 
                        mapptr += 1 + ffz(~v2);
                }
 
                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);
}
 
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, "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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[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [fs/] [adfs/] [map.c] - Blame information for rev 1765

Line No.	Rev	Author	Line
1	1275	phoenix	`/*`
2			`* linux/fs/adfs/map.c`
3			`*`
4			`* Copyright (C) 1997-1999 Russell King`
5			`*`
6			`* This program is free software; you can redistribute it and/or modify`
7			`* it under the terms of the GNU General Public License version 2 as`
8			`* published by the Free Software Foundation.`
9			`*/`
10			`#include <linux/version.h>`
11			`#include <linux/errno.h>`
12			`#include <linux/fs.h>`
13			`#include <linux/adfs_fs.h>`
14			`#include <linux/spinlock.h>`
15
16			`#include "adfs.h"`
17
18			`/*`
19			`* For the future...`
20			`*/`
21			`static rwlock_t adfs_map_lock;`
22
23			`#define GET_FRAG_ID(_map,_start,_idmask) \`
24			`({ \`
25			`unsigned long _v2, _frag; \`
26			`unsigned int _tmp; \`
27			`_tmp = _start >> 5; \`
28			`_frag = le32_to_cpu(_map[_tmp]); \`
29			`_v2 = le32_to_cpu(_map[_tmp + 1]); \`
30			`_tmp = start & 31; \`
31			`_frag = (_frag >> _tmp) \| (_v2 << (32 - _tmp)); \`
32			`_frag & _idmask; \`
33			`})`
34
35			`/*`
36			`* return the map bit offset of the fragment frag_id in`
37			`* the zone dm.`
38			`* Note that the loop is optimised for best asm code -`
39			`* look at the output of:`
40			`* gcc -D__KERNEL__ -O2 -I../../include -o - -S map.c`
41			`*/`
42			`static int`
43			`lookup_zone(const struct adfs_discmap *dm, const unsigned int idlen,`
44			`const unsigned int frag_id, unsigned int *offset)`
45			`{`
46			`const unsigned int mapsize = dm->dm_endbit;`
47			`const unsigned int idmask = (1 << idlen) - 1;`
48			`unsigned long map = ((unsigned long )dm->dm_bh->b_data) + 1;`
49			`unsigned int start = dm->dm_startbit;`
50			`unsigned int mapptr;`
51
52			`do {`
53			`unsigned long frag;`
54
55			`frag = GET_FRAG_ID(map, start, idmask);`
56			`mapptr = start + idlen;`
57
58			`/*`
59			`* find end of fragment`
60			`*/`
61			`{`
62			`unsigned long v2;`
63
64			`while ((v2 = map[mapptr >> 5] >> (mapptr & 31)) == 0) {`
65			`mapptr = (mapptr & ~31) + 32;`
66			`if (mapptr >= mapsize)`
67			`goto error;`
68			`}`
69
70			`mapptr += 1 + ffz(~v2);`
71			`}`
72
73			`if (frag == frag_id)`
74			`goto found;`
75			`again:`
76			`start = mapptr;`
77			`} while (mapptr < mapsize);`
78
79			`error:`
80			`return -1;`
81
82			`found:`
83			`{`
84			`int length = mapptr - start;`
85			`if (*offset >= length) {`
86			`*offset -= length;`
87			`goto again;`
88			`}`
89			`}`
90			`return start + *offset;`
91			`}`
92
93			`/*`
94			`* Scan the free space map, for this zone, calculating the total`
95			`* number of map bits in each free space fragment.`
96			`*`
97			`* Note: idmask is limited to 15 bits [3.2]`
98			`*/`
99			`static unsigned int`
100			`scan_free_map(struct adfs_sb_info asb, struct adfs_discmap dm)`
101			`{`
102			`const unsigned int mapsize = dm->dm_endbit + 32;`
103			`const unsigned int idlen = asb->s_idlen;`
104			`const unsigned int frag_idlen = idlen <= 15 ? idlen : 15;`
105			`const unsigned int idmask = (1 << frag_idlen) - 1;`
106			`unsigned long map = (unsigned long )dm->dm_bh->b_data;`
107			`unsigned int start = 8, mapptr;`
108			`unsigned long frag;`
109			`unsigned long total = 0;`
110
111			`/*`
112			`* get fragment id`
113			`*/`
114			`frag = GET_FRAG_ID(map, start, idmask);`
115
116			`/*`
117			`* If the freelink is null, then no free fragments`
118			`* exist in this zone.`
119			`*/`
120			`if (frag == 0)`
121			`return 0;`
122
123			`do {`
124			`start += frag;`
125
126			`/*`
127			`* get fragment id`
128			`*/`
129			`frag = GET_FRAG_ID(map, start, idmask);`
130			`mapptr = start + idlen;`
131
132			`/*`
133			`* find end of fragment`
134			`*/`
135			`{`
136			`unsigned long v2;`
137
138			`while ((v2 = map[mapptr >> 5] >> (mapptr & 31)) == 0) {`
139			`mapptr = (mapptr & ~31) + 32;`
140			`if (mapptr >= mapsize)`
141			`goto error;`
142			`}`
143
144			`mapptr += 1 + ffz(~v2);`
145			`}`
146
147			`total += mapptr - start;`
148			`} while (frag >= idlen + 1);`
149
150			`if (frag != 0)`
151			`printk(KERN_ERR "adfs: undersized free fragment\n");`
152
153			`return total;`
154			`error:`
155			`printk(KERN_ERR "adfs: oversized free fragment\n");`
156			`return 0;`
157			`}`
158
159			`static int`
160			`scan_map(struct adfs_sb_info *asb, unsigned int zone,`
161			`const unsigned int frag_id, unsigned int mapoff)`
162			`{`
163			`const unsigned int idlen = asb->s_idlen;`
164			`struct adfs_discmap dm, dm_end;`
165			`int result;`
166
167			`dm = asb->s_map + zone;`
168			`zone = asb->s_map_size;`
169			`dm_end = asb->s_map + zone;`
170
171			`do {`
172			`result = lookup_zone(dm, idlen, frag_id, &mapoff);`
173
174			`if (result != -1)`
175			`goto found;`
176
177			`dm ++;`
178			`if (dm == dm_end)`
179			`dm = asb->s_map;`
180			`} while (--zone > 0);`
181
182			`return -1;`
183			`found:`
184			`result -= dm->dm_startbit;`
185			`result += dm->dm_startblk;`
186
187			`return result;`
188			`}`
189
190			`/*`
191			`* calculate the amount of free blocks in the map.`
192			`*`
193			`* n=1`
194			`* total_free = E(free_in_zone_n)`
195			`* nzones`
196			`*/`
197			`unsigned int`
198			`adfs_map_free(struct super_block *sb)`
199			`{`
200			`struct adfs_sb_info *asb = &sb->u.adfs_sb;`
201			`struct adfs_discmap *dm;`
202			`unsigned int total = 0;`
203			`unsigned int zone;`
204
205			`dm = asb->s_map;`
206			`zone = asb->s_map_size;`
207
208			`do {`
209			`total += scan_free_map(asb, dm++);`
210			`} while (--zone > 0);`
211
212			`return signed_asl(total, asb->s_map2blk);`
213			`}`
214
215			`int adfs_map_lookup (struct super_block *sb, int frag_id, int offset)`
216			`{`
217			`struct adfs_sb_info *asb = &sb->u.adfs_sb;`
218			`unsigned int zone, mapoff;`
219			`int result;`
220
221			`/*`
222			`* map & root fragment is special - it starts in the center of the`
223			`* disk. The other fragments start at zone (frag / ids_per_zone)`
224			`*/`
225			`if (frag_id == ADFS_ROOT_FRAG)`
226			`zone = asb->s_map_size >> 1;`
227			`else`
228			`zone = frag_id / asb->s_ids_per_zone;`
229
230			`if (zone >= asb->s_map_size)`
231			`goto bad_fragment;`
232
233			`/* Convert sector offset to map offset */`
234			`mapoff = signed_asl(offset, -asb->s_map2blk);`
235
236			`read_lock(&adfs_map_lock);`
237			`result = scan_map(asb, zone, frag_id, mapoff);`
238			`read_unlock(&adfs_map_lock);`
239
240			`if (result > 0) {`
241			`unsigned int secoff;`
242
243			`/* Calculate sector offset into map block */`
244			`secoff = offset - signed_asl(mapoff, asb->s_map2blk);`
245			`return secoff + signed_asl(result, asb->s_map2blk);`
246			`}`
247
248			`adfs_error(sb, "fragment %04X at offset %d not found in map",`
249			`frag_id, offset);`
250			`return 0;`
251
252			`bad_fragment:`
253			`adfs_error(sb, "fragment %X is invalid (zone = %d, max = %d)",`
254			`frag_id, zone, asb->s_map_size);`
255			`return 0;`
256			`}`