/*
* This will never put the page into the free list, the caller has
* a reference on the page.
*/
void delete_from_swap_cache_nolock(struct page *page)
{
if (!PageLocked(page))
BUG();
if (block_flushpage(page, 0))
lru_cache_del(page);
spin_lock(&pagecache_lock);
ClearPageDirty(page);
__delete_from_swap_cache(page);
spin_unlock(&pagecache_lock);
page_cache_release(page);
}
/*
* The swap lock map insists that pages be in the page cache!
* Therefore we can't use it. Later when we can remove the need for the
* lock map and we can reduce the number of functions exported.
*/
void rw_swap_page_nolock(int rw, swp_entry_t entry, char *buf)
{
struct page *page = virt_to_page(buf);
if (!PageLocked(page))
PAGE_BUG(page);
if (page->mapping)
PAGE_BUG(page);
/* needs sync_page to wait I/O completation */
page->mapping = &swapper_space;
if (rw_swap_page_base(rw, entry, page))
lock_page(page);
if (!block_flushpage(page, 0))
PAGE_BUG(page);
page->mapping = NULL;
UnlockPage(page);
}
/*
* This must be called only on pages that have
* been verified to be in the swap cache and locked.
* It will never put the page into the free list,
* the caller has a reference on the page.
*/
void delete_from_swap_cache(struct page *page)
{
swp_entry_t entry;
if (!PageLocked(page))
BUG();
block_flushpage(page, 0);
entry.val = page->index;
spin_lock(&pagecache_lock);
__delete_from_swap_cache(page);
spin_unlock(&pagecache_lock);
swap_free(entry);
page_cache_release(page);
}
/*
* Work out if there are any other processes sharing this
* swap cache page. Free it if you can. Return success.
*/
int remove_exclusive_swap_page(struct page *page)
{
int retval;
struct swap_info_struct * p;
swp_entry_t entry;
if (!PageLocked(page))
BUG();
if (!PageSwapCache(page))
return 0;
if (page_count(page) - !!page->buffers != 2) /* 2: us + cache */
return 0;
entry.val = page->index;
p = swap_info_get(entry);
if (!p)
return 0;
/* Is the only swap cache user the cache itself? */
retval = 0;
if (p->swap_map[SWP_OFFSET(entry)] == 1) {
/* Recheck the page count with the pagecache lock held.. */
spin_lock(&pagecache_lock);
if (page_count(page) - !!page->buffers == 2) {
__delete_from_swap_cache(page);
SetPageDirty(page);
retval = 1;
}
spin_unlock(&pagecache_lock);
}
swap_info_put(p);
if (retval) {
block_flushpage(page, 0);
swap_free(entry);
page_cache_release(page);
}
return retval;
}