block.c

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#include <ds/bitmap.h>
#include <minix.h>

blk_t minix_block_alloc(struct minix *desc)
{
    /* look for a free zone: bit i of the bitmap is zone firstdatazone +
     * i - 1 (bit 0 is reserved) */
    blk_t blk = 1;
    for (; blk <= desc->zmap.max_idx && bitmap_check(&desc->zmap, blk); ++blk);
 
    /* out of zones */
    if (blk > desc->zmap.max_idx)
        return 0;
 
    bitmap_set(&desc->zmap, blk);
 
    /* write the bitmap back now (it could be deferred) */
    vfs_write(desc->supernode, desc->zmap_off, desc->superblock->zmap_blocks * desc->bs, desc->zmap.map);
 
    return desc->superblock->firstdatazone + blk - 1;
}

void minix_block_free(struct minix *desc, blk_t blk)
{
    /* not a data zone: nothing to free */
    if (blk < desc->superblock->firstdatazone)
        return;
 
    blk = blk - desc->superblock->firstdatazone + 1;
 
    if (blk > desc->zmap.max_idx)
        return;
 
    /* clear its bit; a cached copy of the block (an indirect zone's
     * table) goes too */
    bitmap_clear(&desc->zmap, blk);
    bcache_remove(desc->bcache, blk + desc->superblock->firstdatazone - 1);
 
    /* write the bitmap back now (it could be deferred) */
    vfs_write(desc->supernode, desc->zmap_off, desc->superblock->zmap_blocks * desc->bs, desc->zmap.map);
}

ssize_t minix_block_read(struct minix *desc, blk_t blk, void *buf)
{
    return vfs_read(desc->supernode, blk * desc->bs, desc->bs, buf);
}

ssize_t minix_block_write(struct minix *desc, blk_t blk, void *buf)
{
    return vfs_write(desc->supernode, blk * desc->bs, desc->bs, buf);
}

int minix_bcache_get(struct minix *desc, blk_t blk, void **data)
{
    int err = 0;
    void *r = NULL;
 
    if ((r = bcache_find(desc->bcache, blk))) {
        *data = r;
        return 0;
    }
 
    r = kmalloc(desc->bs, &M_BUFFER, 0);
    if (!r) goto e_nomem;
 
    if ((err = minix_block_read(desc, blk, r)) < 0)
        goto error;
 
    bcache_insert(desc->bcache, blk, r);
 
    *data = r;
    return 0;
 
e_nomem:
    err = -ENOMEM;
 
error:
    return err;
}