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zram/xvmalloc: combine duplicate block delete code

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This patch eliminates duplicate code.  The remove_block_head function
is a special case of remove_block which can be contained in remove_block
without confusion.

The portion of code in remove_block_head which was noted as "DEBUG ONLY"
is now mandatory.  Doing this provides consistent management of the double
linked list of blocks under a freelist and makes this consolidation
of delete block code safe.  The first and last blocks will have NULL
pointers in their previous and next page pointers respectively.

Additionally, any time a block is removed from a free list the next and
previous pointers will be set to NULL to avoid misuse outside xvmalloc.

Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Acked-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Robert Jennings 2011-01-28 09:01:55 -06:00 committed by Greg Kroah-Hartman
parent 2787f959d6
commit 939b3f0b14
1 changed files with 31 additions and 42 deletions
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73
drivers/staging/zram/xvmalloc.c
View File

@ -212,55 +212,15 @@ static void insert_block(struct xv_pool *pool, struct page *page, u32 offset,
__set_bit(flindex, &pool->flbitmap);
}
/*
* Remove block from head of freelist. Index 'slindex' identifies the freelist.
*/
static void remove_block_head(struct xv_pool *pool,
struct block_header *block, u32 slindex)
{
struct block_header *tmpblock;
u32 flindex = slindex / BITS_PER_LONG;
pool->freelist[slindex].page = block->link.next_page;
pool->freelist[slindex].offset = block->link.next_offset;
block->link.prev_page = NULL;
block->link.prev_offset = 0;
if (!pool->freelist[slindex].page) {
__clear_bit(slindex % BITS_PER_LONG, &pool->slbitmap[flindex]);
if (!pool->slbitmap[flindex])
__clear_bit(flindex, &pool->flbitmap);
} else {
/*
* DEBUG ONLY: We need not reinitialize freelist head previous
* pointer to 0 - we never depend on its value. But just for
* sanity, lets do it.
*/
tmpblock = get_ptr_atomic(pool->freelist[slindex].page,
pool->freelist[slindex].offset, KM_USER1);
tmpblock->link.prev_page = NULL;
tmpblock->link.prev_offset = 0;
put_ptr_atomic(tmpblock, KM_USER1);
}
}
/*
* Remove block from freelist. Index 'slindex' identifies the freelist.
*/
static void remove_block(struct xv_pool *pool, struct page *page, u32 offset,
struct block_header *block, u32 slindex)
{
u32 flindex;
u32 flindex = slindex / BITS_PER_LONG;
struct block_header *tmpblock;
if (pool->freelist[slindex].page == page
&& pool->freelist[slindex].offset == offset) {
remove_block_head(pool, block, slindex);
return;
}
flindex = slindex / BITS_PER_LONG;
if (block->link.prev_page) {
tmpblock = get_ptr_atomic(block->link.prev_page,
block->link.prev_offset, KM_USER1);
@ -276,6 +236,35 @@ static void remove_block(struct xv_pool *pool, struct page *page, u32 offset,
tmpblock->link.prev_offset = block->link.prev_offset;
put_ptr_atomic(tmpblock, KM_USER1);
}
/* Is this block is at the head of the freelist? */
if (pool->freelist[slindex].page == page
&& pool->freelist[slindex].offset == offset) {
pool->freelist[slindex].page = block->link.next_page;
pool->freelist[slindex].offset = block->link.next_offset;
if (pool->freelist[slindex].page) {
struct block_header *tmpblock;
tmpblock = get_ptr_atomic(pool->freelist[slindex].page,
pool->freelist[slindex].offset,
KM_USER1);
tmpblock->link.prev_page = NULL;
tmpblock->link.prev_offset = 0;
put_ptr_atomic(tmpblock, KM_USER1);
} else {
/* This freelist bucket is empty */
__clear_bit(slindex % BITS_PER_LONG,
&pool->slbitmap[flindex]);
if (!pool->slbitmap[flindex])
__clear_bit(flindex, &pool->flbitmap);
}
}
block->link.prev_page = NULL;
block->link.prev_offset = 0;
block->link.next_page = NULL;
block->link.next_offset = 0;
}
/*
@ -384,7 +373,7 @@ int xv_malloc(struct xv_pool *pool, u32 size, struct page **page,
block = get_ptr_atomic(*page, *offset, KM_USER0);
remove_block_head(pool, block, index);
remove_block(pool, *page, *offset, block, index);
/* Split the block if required */
tmpoffset = *offset + size + XV_ALIGN;