2 * linux/fs/affs/bitmap.c
4 * (c) 1996 Hans-Joachim Widmaier
6 * bitmap.c contains the code that handles all bitmap related stuff -
7 * block allocation, deallocation, calculation of free space.
10 #include <linux/sched.h>
11 #include <linux/affs_fs.h>
12 #include <linux/stat.h>
13 #include <linux/kernel.h>
14 #include <linux/slab.h>
15 #include <linux/string.h>
16 #include <linux/locks.h>
17 #include <linux/bitops.h>
18 #include <linux/amigaffs.h>
20 /* This is, of course, shamelessly stolen from fs/minix */
22 static int nibblemap[] = { 0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4 };
25 affs_count_free_bits(u32 blocksize, const void *data)
33 for (blocksize /= 4; blocksize > 0; blocksize--) {
36 free += nibblemap[tmp & 0xf];
45 affs_count_free_blocks(struct super_block *sb)
47 struct affs_bm_info *bm;
51 pr_debug("AFFS: count_free_blocks()\n");
53 if (sb->s_flags & MS_RDONLY)
56 down(&AFFS_SB->s_bmlock);
58 bm = AFFS_SB->s_bitmap;
60 for (i = AFFS_SB->s_bmap_count; i > 0; bm++, i--)
63 up(&AFFS_SB->s_bmlock);
69 affs_free_block(struct super_block *sb, u32 block)
71 struct affs_bm_info *bm;
72 struct buffer_head *bh;
73 u32 blk, bmap, bit, mask, tmp;
76 pr_debug("AFFS: free_block(%u)\n", block);
78 if (block > AFFS_SB->s_partition_size)
81 blk = block - AFFS_SB->s_reserved;
82 bmap = blk / AFFS_SB->s_bmap_bits;
83 bit = blk % AFFS_SB->s_bmap_bits;
84 bm = &AFFS_SB->s_bitmap[bmap];
86 down(&AFFS_SB->s_bmlock);
88 bh = AFFS_SB->s_bmap_bh;
89 if (AFFS_SB->s_last_bmap != bmap) {
91 bh = affs_bread(sb, bm->bm_key);
94 AFFS_SB->s_bmap_bh = bh;
95 AFFS_SB->s_last_bmap = bmap;
98 mask = 1 << (bit & 31);
99 data = (u32 *)bh->b_data + bit / 32 + 1;
101 /* mark block free */
102 tmp = be32_to_cpu(*data);
105 *data = cpu_to_be32(tmp | mask);
108 tmp = be32_to_cpu(*(u32 *)bh->b_data);
109 *(u32 *)bh->b_data = cpu_to_be32(tmp - mask);
111 mark_buffer_dirty(bh);
115 up(&AFFS_SB->s_bmlock);
119 affs_warning(sb,"affs_free_block","Trying to free block %u which is already free", block);
120 up(&AFFS_SB->s_bmlock);
124 affs_error(sb,"affs_free_block","Cannot read bitmap block %u", bm->bm_key);
125 AFFS_SB->s_bmap_bh = NULL;
126 AFFS_SB->s_last_bmap = ~0;
127 up(&AFFS_SB->s_bmlock);
131 affs_error(sb, "affs_free_block","Block %u outside partition", block);
136 * Allocate a block in the given allocation zone.
137 * Since we have to byte-swap the bitmap on little-endian
138 * machines, this is rather expensive. Therefor we will
139 * preallocate up to 16 blocks from the same word, if
140 * possible. We are not doing preallocations in the
141 * header zone, though.
145 affs_alloc_block(struct inode *inode, u32 goal)
147 struct super_block *sb;
148 struct affs_bm_info *bm;
149 struct buffer_head *bh;
151 u32 blk, bmap, bit, mask, mask2, tmp;
156 pr_debug("AFFS: balloc(inode=%lu,goal=%u): ", inode->i_ino, goal);
158 if (inode->u.affs_i.i_pa_cnt) {
159 pr_debug("%d\n", inode->u.affs_i.i_lastalloc+1);
160 inode->u.affs_i.i_pa_cnt--;
161 return ++inode->u.affs_i.i_lastalloc;
164 if (!goal || goal > AFFS_SB->s_partition_size) {
166 affs_warning(sb, "affs_balloc", "invalid goal %d", goal);
167 //if (!inode->u.affs_i.i_last_block)
168 // affs_warning(sb, "affs_balloc", "no last alloc block");
169 goal = AFFS_SB->s_reserved;
172 blk = goal - AFFS_SB->s_reserved;
173 bmap = blk / AFFS_SB->s_bmap_bits;
174 bm = &AFFS_SB->s_bitmap[bmap];
176 down(&AFFS_SB->s_bmlock);
182 /* search for the next bmap buffer with free bits */
183 i = AFFS_SB->s_bmap_count;
187 if (bmap < AFFS_SB->s_bmap_count)
189 /* restart search at zero */
191 bm = AFFS_SB->s_bitmap;
194 } while (!bm->bm_free);
195 blk = bmap * AFFS_SB->s_bmap_bits;
199 bh = AFFS_SB->s_bmap_bh;
200 if (AFFS_SB->s_last_bmap != bmap) {
202 bh = affs_bread(sb, bm->bm_key);
205 AFFS_SB->s_bmap_bh = bh;
206 AFFS_SB->s_last_bmap = bmap;
209 /* find an unused block in this bitmap block */
210 bit = blk % AFFS_SB->s_bmap_bits;
211 data = (u32 *)bh->b_data + bit / 32 + 1;
212 enddata = (u32 *)((u8 *)bh->b_data + sb->s_blocksize);
213 mask = ~0UL << (bit & 31);
216 tmp = be32_to_cpu(*data) & mask;
220 /* scan the rest of the buffer */
223 if (++data >= enddata)
224 /* didn't find something, can only happen
225 * if scan didn't start at 0, try next bmap
228 } while (!(tmp = *data));
229 tmp = be32_to_cpu(tmp);
232 /* finally look for a free bit in the word */
234 blk += bit + AFFS_SB->s_reserved;
235 mask2 = mask = 1 << (bit & 31);
236 inode->u.affs_i.i_lastalloc = blk;
238 /* prealloc as much as possible within this word */
239 while ((mask2 <<= 1)) {
242 inode->u.affs_i.i_pa_cnt++;
245 bm->bm_free -= inode->u.affs_i.i_pa_cnt + 1;
247 *data = cpu_to_be32(tmp & ~mask);
250 tmp = be32_to_cpu(*(u32 *)bh->b_data);
251 *(u32 *)bh->b_data = cpu_to_be32(tmp + mask);
253 mark_buffer_dirty(bh);
256 up(&AFFS_SB->s_bmlock);
258 pr_debug("%d\n", blk);
262 affs_error(sb,"affs_read_block","Cannot read bitmap block %u", bm->bm_key);
263 AFFS_SB->s_bmap_bh = NULL;
264 AFFS_SB->s_last_bmap = ~0;
266 pr_debug("failed\n");
267 up(&AFFS_SB->s_bmlock);
272 affs_init_bitmap(struct super_block *sb)
274 struct affs_bm_info *bm;
275 struct buffer_head *bmap_bh = NULL, *bh = NULL;
277 u32 size, blk, end, offset, mask;
280 if (sb->s_flags & MS_RDONLY)
283 if (!AFFS_ROOT_TAIL(sb, AFFS_SB->s_root_bh)->bm_flag) {
284 printk(KERN_NOTICE "AFFS: Bitmap invalid - mounting %s read only\n",
285 kdevname(sb->s_dev));
286 sb->s_flags |= MS_RDONLY;
290 AFFS_SB->s_last_bmap = ~0;
291 AFFS_SB->s_bmap_bh = NULL;
292 AFFS_SB->s_bmap_bits = sb->s_blocksize * 8 - 32;
293 AFFS_SB->s_bmap_count = (AFFS_SB->s_partition_size - AFFS_SB->s_reserved +
294 AFFS_SB->s_bmap_bits - 1) / AFFS_SB->s_bmap_bits;
295 size = AFFS_SB->s_bmap_count * sizeof(*bm);
296 bm = AFFS_SB->s_bitmap = kmalloc(size, GFP_KERNEL);
297 if (!AFFS_SB->s_bitmap) {
298 printk(KERN_ERR "AFFS: Bitmap allocation failed\n");
301 memset(AFFS_SB->s_bitmap, 0, size);
303 bmap_blk = (u32 *)AFFS_SB->s_root_bh->b_data;
304 blk = sb->s_blocksize / 4 - 49;
307 for (i = AFFS_SB->s_bmap_count; i > 0; bm++, i--) {
310 bm->bm_key = be32_to_cpu(bmap_blk[blk]);
311 bh = affs_bread(sb, bm->bm_key);
313 printk(KERN_ERR "AFFS: Cannot read bitmap\n");
317 if (affs_checksum_block(sb, bh)) {
318 printk(KERN_WARNING "AFFS: Bitmap %u invalid - mounting %s read only.\n",
319 bm->bm_key, kdevname(sb->s_dev));
320 sb->s_flags |= MS_RDONLY;
323 pr_debug("AFFS: read bitmap block %d: %d\n", blk, bm->bm_key);
324 bm->bm_free = affs_count_free_bits(sb->s_blocksize - 4, bh->b_data + 4);
326 /* Don't try read the extension if this is the last block,
327 * but we also need the right bm pointer below
329 if (++blk < end || i == 1)
332 affs_brelse(bmap_bh);
333 bmap_bh = affs_bread(sb, be32_to_cpu(bmap_blk[blk]));
335 printk(KERN_ERR "AFFS: Cannot read bitmap extension\n");
339 bmap_blk = (u32 *)bmap_bh->b_data;
341 end = sb->s_blocksize / 4 - 1;
344 offset = (AFFS_SB->s_partition_size - AFFS_SB->s_reserved) % AFFS_SB->s_bmap_bits;
345 mask = ~(0xFFFFFFFFU << (offset & 31));
346 pr_debug("last word: %d %d %d\n", offset, offset / 32 + 1, mask);
347 offset = offset / 32 + 1;
352 /* Mark unused bits in the last word as allocated */
353 old = be32_to_cpu(((u32 *)bh->b_data)[offset]);
356 ((u32 *)bh->b_data)[offset] = cpu_to_be32(new);
359 //old = be32_to_cpu(*(u32 *)bh->b_data);
360 //*(u32 *)bh->b_data = cpu_to_be32(old - new);
361 //mark_buffer_dirty(bh);
363 /* correct offset for the bitmap count below */
366 while (++offset < sb->s_blocksize / 4)
367 ((u32 *)bh->b_data)[offset] = 0;
368 ((u32 *)bh->b_data)[0] = 0;
369 ((u32 *)bh->b_data)[0] = cpu_to_be32(-affs_checksum_block(sb, bh));
370 mark_buffer_dirty(bh);
372 /* recalculate bitmap count for last block */
374 bm->bm_free = affs_count_free_bits(sb->s_blocksize - 4, bh->b_data + 4);
378 affs_brelse(bmap_bh);