390 строки
8.8 KiB
C
390 строки
8.8 KiB
C
/*
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* linux/fs/affs/bitmap.c
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*
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* (c) 1996 Hans-Joachim Widmaier
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*
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* bitmap.c contains the code that handles all bitmap related stuff -
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* block allocation, deallocation, calculation of free space.
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*/
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#include "affs.h"
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/* This is, of course, shamelessly stolen from fs/minix */
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static const int nibblemap[] = { 0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4 };
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static u32
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affs_count_free_bits(u32 blocksize, const void *data)
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{
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const u32 *map;
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u32 free;
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u32 tmp;
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map = data;
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free = 0;
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for (blocksize /= 4; blocksize > 0; blocksize--) {
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tmp = *map++;
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while (tmp) {
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free += nibblemap[tmp & 0xf];
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tmp >>= 4;
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}
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}
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return free;
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}
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u32
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affs_count_free_blocks(struct super_block *sb)
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{
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struct affs_bm_info *bm;
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u32 free;
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int i;
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pr_debug("AFFS: count_free_blocks()\n");
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if (sb->s_flags & MS_RDONLY)
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return 0;
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mutex_lock(&AFFS_SB(sb)->s_bmlock);
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bm = AFFS_SB(sb)->s_bitmap;
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free = 0;
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for (i = AFFS_SB(sb)->s_bmap_count; i > 0; bm++, i--)
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free += bm->bm_free;
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mutex_unlock(&AFFS_SB(sb)->s_bmlock);
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return free;
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}
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void
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affs_free_block(struct super_block *sb, u32 block)
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{
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struct affs_sb_info *sbi = AFFS_SB(sb);
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struct affs_bm_info *bm;
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struct buffer_head *bh;
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u32 blk, bmap, bit, mask, tmp;
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__be32 *data;
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pr_debug("AFFS: free_block(%u)\n", block);
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if (block > sbi->s_partition_size)
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goto err_range;
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blk = block - sbi->s_reserved;
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bmap = blk / sbi->s_bmap_bits;
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bit = blk % sbi->s_bmap_bits;
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bm = &sbi->s_bitmap[bmap];
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mutex_lock(&sbi->s_bmlock);
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bh = sbi->s_bmap_bh;
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if (sbi->s_last_bmap != bmap) {
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affs_brelse(bh);
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bh = affs_bread(sb, bm->bm_key);
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if (!bh)
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goto err_bh_read;
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sbi->s_bmap_bh = bh;
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sbi->s_last_bmap = bmap;
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}
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mask = 1 << (bit & 31);
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data = (__be32 *)bh->b_data + bit / 32 + 1;
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/* mark block free */
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tmp = be32_to_cpu(*data);
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if (tmp & mask)
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goto err_free;
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*data = cpu_to_be32(tmp | mask);
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/* fix checksum */
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tmp = be32_to_cpu(*(__be32 *)bh->b_data);
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*(__be32 *)bh->b_data = cpu_to_be32(tmp - mask);
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mark_buffer_dirty(bh);
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sb->s_dirt = 1;
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bm->bm_free++;
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mutex_unlock(&sbi->s_bmlock);
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return;
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err_free:
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affs_warning(sb,"affs_free_block","Trying to free block %u which is already free", block);
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mutex_unlock(&sbi->s_bmlock);
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return;
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err_bh_read:
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affs_error(sb,"affs_free_block","Cannot read bitmap block %u", bm->bm_key);
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sbi->s_bmap_bh = NULL;
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sbi->s_last_bmap = ~0;
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mutex_unlock(&sbi->s_bmlock);
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return;
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err_range:
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affs_error(sb, "affs_free_block","Block %u outside partition", block);
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return;
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}
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/*
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* Allocate a block in the given allocation zone.
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* Since we have to byte-swap the bitmap on little-endian
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* machines, this is rather expensive. Therefor we will
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* preallocate up to 16 blocks from the same word, if
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* possible. We are not doing preallocations in the
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* header zone, though.
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*/
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u32
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affs_alloc_block(struct inode *inode, u32 goal)
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{
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struct super_block *sb;
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struct affs_sb_info *sbi;
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struct affs_bm_info *bm;
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struct buffer_head *bh;
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__be32 *data, *enddata;
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u32 blk, bmap, bit, mask, mask2, tmp;
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int i;
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sb = inode->i_sb;
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sbi = AFFS_SB(sb);
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pr_debug("AFFS: balloc(inode=%lu,goal=%u): ", inode->i_ino, goal);
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if (AFFS_I(inode)->i_pa_cnt) {
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pr_debug("%d\n", AFFS_I(inode)->i_lastalloc+1);
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AFFS_I(inode)->i_pa_cnt--;
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return ++AFFS_I(inode)->i_lastalloc;
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}
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if (!goal || goal > sbi->s_partition_size) {
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if (goal)
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affs_warning(sb, "affs_balloc", "invalid goal %d", goal);
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//if (!AFFS_I(inode)->i_last_block)
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// affs_warning(sb, "affs_balloc", "no last alloc block");
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goal = sbi->s_reserved;
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}
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blk = goal - sbi->s_reserved;
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bmap = blk / sbi->s_bmap_bits;
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bm = &sbi->s_bitmap[bmap];
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mutex_lock(&sbi->s_bmlock);
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if (bm->bm_free)
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goto find_bmap_bit;
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find_bmap:
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/* search for the next bmap buffer with free bits */
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i = sbi->s_bmap_count;
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do {
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if (--i < 0)
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goto err_full;
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bmap++;
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bm++;
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if (bmap < sbi->s_bmap_count)
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continue;
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/* restart search at zero */
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bmap = 0;
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bm = sbi->s_bitmap;
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} while (!bm->bm_free);
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blk = bmap * sbi->s_bmap_bits;
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find_bmap_bit:
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bh = sbi->s_bmap_bh;
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if (sbi->s_last_bmap != bmap) {
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affs_brelse(bh);
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bh = affs_bread(sb, bm->bm_key);
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if (!bh)
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goto err_bh_read;
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sbi->s_bmap_bh = bh;
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sbi->s_last_bmap = bmap;
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}
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/* find an unused block in this bitmap block */
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bit = blk % sbi->s_bmap_bits;
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data = (__be32 *)bh->b_data + bit / 32 + 1;
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enddata = (__be32 *)((u8 *)bh->b_data + sb->s_blocksize);
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mask = ~0UL << (bit & 31);
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blk &= ~31UL;
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tmp = be32_to_cpu(*data);
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if (tmp & mask)
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goto find_bit;
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/* scan the rest of the buffer */
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do {
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blk += 32;
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if (++data >= enddata)
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/* didn't find something, can only happen
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* if scan didn't start at 0, try next bmap
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*/
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goto find_bmap;
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} while (!*data);
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tmp = be32_to_cpu(*data);
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mask = ~0;
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find_bit:
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/* finally look for a free bit in the word */
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bit = ffs(tmp & mask) - 1;
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blk += bit + sbi->s_reserved;
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mask2 = mask = 1 << (bit & 31);
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AFFS_I(inode)->i_lastalloc = blk;
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/* prealloc as much as possible within this word */
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while ((mask2 <<= 1)) {
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if (!(tmp & mask2))
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break;
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AFFS_I(inode)->i_pa_cnt++;
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mask |= mask2;
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}
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bm->bm_free -= AFFS_I(inode)->i_pa_cnt + 1;
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*data = cpu_to_be32(tmp & ~mask);
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/* fix checksum */
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tmp = be32_to_cpu(*(__be32 *)bh->b_data);
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*(__be32 *)bh->b_data = cpu_to_be32(tmp + mask);
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mark_buffer_dirty(bh);
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sb->s_dirt = 1;
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mutex_unlock(&sbi->s_bmlock);
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pr_debug("%d\n", blk);
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return blk;
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err_bh_read:
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affs_error(sb,"affs_read_block","Cannot read bitmap block %u", bm->bm_key);
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sbi->s_bmap_bh = NULL;
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sbi->s_last_bmap = ~0;
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err_full:
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mutex_unlock(&sbi->s_bmlock);
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pr_debug("failed\n");
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return 0;
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}
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int affs_init_bitmap(struct super_block *sb, int *flags)
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{
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struct affs_bm_info *bm;
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struct buffer_head *bmap_bh = NULL, *bh = NULL;
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__be32 *bmap_blk;
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u32 size, blk, end, offset, mask;
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int i, res = 0;
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struct affs_sb_info *sbi = AFFS_SB(sb);
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if (*flags & MS_RDONLY)
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return 0;
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if (!AFFS_ROOT_TAIL(sb, sbi->s_root_bh)->bm_flag) {
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printk(KERN_NOTICE "AFFS: Bitmap invalid - mounting %s read only\n",
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sb->s_id);
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*flags |= MS_RDONLY;
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return 0;
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}
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sbi->s_last_bmap = ~0;
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sbi->s_bmap_bh = NULL;
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sbi->s_bmap_bits = sb->s_blocksize * 8 - 32;
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sbi->s_bmap_count = (sbi->s_partition_size - sbi->s_reserved +
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sbi->s_bmap_bits - 1) / sbi->s_bmap_bits;
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size = sbi->s_bmap_count * sizeof(*bm);
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bm = sbi->s_bitmap = kzalloc(size, GFP_KERNEL);
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if (!sbi->s_bitmap) {
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printk(KERN_ERR "AFFS: Bitmap allocation failed\n");
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return -ENOMEM;
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}
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bmap_blk = (__be32 *)sbi->s_root_bh->b_data;
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blk = sb->s_blocksize / 4 - 49;
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end = blk + 25;
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for (i = sbi->s_bmap_count; i > 0; bm++, i--) {
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affs_brelse(bh);
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bm->bm_key = be32_to_cpu(bmap_blk[blk]);
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bh = affs_bread(sb, bm->bm_key);
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if (!bh) {
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printk(KERN_ERR "AFFS: Cannot read bitmap\n");
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res = -EIO;
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goto out;
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}
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if (affs_checksum_block(sb, bh)) {
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printk(KERN_WARNING "AFFS: Bitmap %u invalid - mounting %s read only.\n",
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bm->bm_key, sb->s_id);
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*flags |= MS_RDONLY;
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goto out;
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}
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pr_debug("AFFS: read bitmap block %d: %d\n", blk, bm->bm_key);
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bm->bm_free = affs_count_free_bits(sb->s_blocksize - 4, bh->b_data + 4);
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/* Don't try read the extension if this is the last block,
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* but we also need the right bm pointer below
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*/
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if (++blk < end || i == 1)
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continue;
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if (bmap_bh)
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affs_brelse(bmap_bh);
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bmap_bh = affs_bread(sb, be32_to_cpu(bmap_blk[blk]));
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if (!bmap_bh) {
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printk(KERN_ERR "AFFS: Cannot read bitmap extension\n");
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res = -EIO;
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goto out;
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}
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bmap_blk = (__be32 *)bmap_bh->b_data;
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blk = 0;
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end = sb->s_blocksize / 4 - 1;
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}
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offset = (sbi->s_partition_size - sbi->s_reserved) % sbi->s_bmap_bits;
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mask = ~(0xFFFFFFFFU << (offset & 31));
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pr_debug("last word: %d %d %d\n", offset, offset / 32 + 1, mask);
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offset = offset / 32 + 1;
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if (mask) {
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u32 old, new;
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/* Mark unused bits in the last word as allocated */
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old = be32_to_cpu(((__be32 *)bh->b_data)[offset]);
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new = old & mask;
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//if (old != new) {
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((__be32 *)bh->b_data)[offset] = cpu_to_be32(new);
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/* fix checksum */
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//new -= old;
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//old = be32_to_cpu(*(__be32 *)bh->b_data);
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//*(__be32 *)bh->b_data = cpu_to_be32(old - new);
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//mark_buffer_dirty(bh);
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//}
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/* correct offset for the bitmap count below */
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//offset++;
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}
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while (++offset < sb->s_blocksize / 4)
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((__be32 *)bh->b_data)[offset] = 0;
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((__be32 *)bh->b_data)[0] = 0;
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((__be32 *)bh->b_data)[0] = cpu_to_be32(-affs_checksum_block(sb, bh));
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mark_buffer_dirty(bh);
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/* recalculate bitmap count for last block */
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bm--;
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bm->bm_free = affs_count_free_bits(sb->s_blocksize - 4, bh->b_data + 4);
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out:
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affs_brelse(bh);
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affs_brelse(bmap_bh);
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return res;
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}
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void affs_free_bitmap(struct super_block *sb)
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{
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struct affs_sb_info *sbi = AFFS_SB(sb);
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if (!sbi->s_bitmap)
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return;
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affs_brelse(sbi->s_bmap_bh);
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sbi->s_bmap_bh = NULL;
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sbi->s_last_bmap = ~0;
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kfree(sbi->s_bitmap);
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sbi->s_bitmap = NULL;
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}
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