int ext4_block_cache_shake(struct ext4_blockdev *bdev)
{
int r = EOK;
struct ext4_buf *buf;
if (bdev->bc->dont_shake)
return EOK;
bdev->bc->dont_shake = true;
while (!RB_EMPTY(&bdev->bc->lru_root) &&
ext4_bcache_is_full(bdev->bc)) {
buf = ext4_buf_lowest_lru(bdev->bc);
ext4_assert(buf);
if (ext4_bcache_test_flag(buf, BC_DIRTY)) {
r = ext4_block_flush_buf(bdev, buf);
if (r != EOK)
break;
}
ext4_bcache_drop_buf(bdev->bc, buf);
}
bdev->bc->dont_shake = false;
return r;
}
int ext4_block_get(struct ext4_blockdev *bdev, struct ext4_block *b,
uint64_t lba)
{
uint64_t pba;
uint32_t pb_cnt;
uint32_t i;
bool is_new;
int r;
ext4_assert(bdev && b);
if(!(bdev->flags & EXT4_BDEV_INITIALIZED))
return EIO;
if(!(lba < bdev->lg_bcnt))
return ERANGE;
b->dirty = 0;
b->lb_id = lba;
/*If cache is full we have to flush it anyway :(*/
if(ext4_bcache_is_full(bdev->bc) && bdev->cache_write_back){
uint32_t free_candidate = bdev->bc->cnt;
uint32_t min_lru = 0xFFFFFFFF;
for (i = 0; i < bdev->bc->cnt; ++i) {
/*Check if buffer free was delayed.*/
if(!bdev->bc->free_delay[i])
continue;
/*Check reference counter.*/
if(bdev->bc->refctr[i])
continue;
if(bdev->bc->lru_id[i] < min_lru){
min_lru = bdev->bc->lru_id[i];
free_candidate = i;
continue;
}
}
if(free_candidate < bdev->bc->cnt){
/*Buffer free was delayed and have no reference. Flush it.*/
r = ext4_blocks_set_direct(bdev,
bdev->bc->data + bdev->bc->itemsize * free_candidate,
bdev->bc->lba[free_candidate], 1);
if(r != EOK)
return r;
/*No delayed anymore*/
bdev->bc->free_delay[free_candidate] = 0;
/*Reduce refered block count*/
bdev->bc->ref_blocks--;
}
}
r = ext4_bcache_alloc(bdev->bc, b, &is_new);
if(r != EOK)
return r;
if(!is_new){
/*Block is in cache. Read from physical device is not required*/
return EOK;
}
if(!b->data)
return ENOMEM;
pba = (lba * bdev->lg_bsize) / bdev->ph_bsize;
pb_cnt = bdev->lg_bsize / bdev->ph_bsize;
r = bdev->bread(bdev, b->data, pba, pb_cnt);
if(r != EOK){
ext4_bcache_free(bdev->bc, b, 0);
b->lb_id = 0;
return r;
}
bdev->bread_ctr++;
return EOK;
}