/*
* Insert block at <page, offset> in freelist of given pool.
* freelist used depends on block size.
*/
static void insert_block(struct xv_pool *pool, struct page *page, u32 offset,
struct block_header *block)
{
u32 flindex, slindex;
struct block_header *nextblock;
slindex = get_index_for_insert(block->size);
flindex = slindex / BITS_PER_LONG;
block->link.prev_page = NULL;
block->link.prev_offset = 0;
block->link.next_page = pool->freelist[slindex].page;
block->link.next_offset = pool->freelist[slindex].offset;
pool->freelist[slindex].page = page;
pool->freelist[slindex].offset = offset;
if (block->link.next_page) {
nextblock = get_ptr_atomic(block->link.next_page,
block->link.next_offset);
nextblock->link.prev_page = page;
nextblock->link.prev_offset = offset;
put_ptr_atomic(nextblock);
/* If there was a next page then the free bits are set. */
return;
}
__set_bit(slindex % BITS_PER_LONG, &pool->slbitmap[flindex]);
__set_bit(flindex, &pool->flbitmap);
}
/*
* Insert block at <pagenum, offset> in freelist of given pool.
* freelist used depends on block size.
*/
static void insert_block(struct xv_pool *pool, u32 pagenum, u32 offset,
struct block_header *block)
{
u32 flindex, slindex;
struct block_header *nextblock;
slindex = get_index_for_insert(block->size);
flindex = slindex / BITS_PER_LONG;
block->link.prev_pagenum = 0;
block->link.prev_offset = 0;
block->link.next_pagenum = pool->freelist[slindex].pagenum;
block->link.next_offset = pool->freelist[slindex].offset;
pool->freelist[slindex].pagenum = pagenum;
pool->freelist[slindex].offset = offset;
if (block->link.next_pagenum) {
nextblock = get_ptr_atomic(block->link.next_pagenum,
block->link.next_offset, KM_USER1);
nextblock->link.prev_pagenum = pagenum;
nextblock->link.prev_offset = offset;
put_ptr_atomic(nextblock, KM_USER1);
}
__set_bit(slindex % BITS_PER_LONG, &pool->slbitmap[flindex]);
__set_bit(flindex, &pool->flbitmap);
}
/*
* Create a memory pool. Allocates freelist, bitmaps and other
* per-pool metadata.
*/
struct xv_pool *xv_create_pool(void)
{
u32 ovhd_size;
struct xv_pool *pool;
ovhd_size = roundup(sizeof(*pool), PAGE_SIZE);
pool = kzalloc(ovhd_size, GFP_KERNEL);
if (!pool)
return NULL;
/* cache the first/second-level indices for PAGE_SIZE allocations */
pagesize_slindex = get_index_for_insert(PAGE_SIZE);
pagesize_flindex = pagesize_slindex / BITS_PER_LONG;
spin_lock_init(&pool->lock);
return pool;
}
/*
* Free block identified with <page, offset>
*/
void xv_free(struct xv_pool *pool, struct page *page, u32 offset)
{
void *page_start;
struct block_header *block, *tmpblock;
offset -= XV_ALIGN;
spin_lock(&pool->lock);
page_start = get_ptr_atomic(page, 0);
block = (struct block_header *)((char *)page_start + offset);
/* Catch double free bugs */
BUG_ON(test_flag(block, BLOCK_FREE));
block->size = ALIGN(block->size, XV_ALIGN);
tmpblock = BLOCK_NEXT(block);
if (offset + block->size + XV_ALIGN == PAGE_SIZE)
tmpblock = NULL;
/* Merge next block if its free */
if (tmpblock && test_flag(tmpblock, BLOCK_FREE)) {
/*
* Blocks smaller than XV_MIN_ALLOC_SIZE
* are not inserted in any free list.
*/
if (tmpblock->size >= XV_MIN_ALLOC_SIZE) {
remove_block(pool, page,
offset + block->size + XV_ALIGN, tmpblock,
get_index_for_insert(tmpblock->size));
}
block->size += tmpblock->size + XV_ALIGN;
}
/* Merge previous block if its free */
if (test_flag(block, PREV_FREE)) {
tmpblock = (struct block_header *)((char *)(page_start) +
get_blockprev(block));
offset = offset - tmpblock->size - XV_ALIGN;
if (tmpblock->size >= XV_MIN_ALLOC_SIZE)
remove_block(pool, page, offset, tmpblock,
get_index_for_insert(tmpblock->size));
tmpblock->size += block->size + XV_ALIGN;
block = tmpblock;
}
/* No used objects in this page. Free it. */
if (block->size == PAGE_SIZE - XV_ALIGN) {
put_ptr_atomic(page_start);
spin_unlock(&pool->lock);
__free_page(page);
stat_dec(&pool->total_pages);
return;
}
set_flag(block, BLOCK_FREE);
if (block->size >= XV_MIN_ALLOC_SIZE)
insert_block(pool, page, offset, block);
if (offset + block->size + XV_ALIGN != PAGE_SIZE) {
tmpblock = BLOCK_NEXT(block);
set_flag(tmpblock, PREV_FREE);
set_blockprev(tmpblock, offset);
}
put_ptr_atomic(page_start);
spin_unlock(&pool->lock);
}
