/*
* "Put" data from a page to frontswap and associate it with the page's
* swaptype and offset. Page must be locked and in the swap cache.
* If frontswap already contains a page with matching swaptype and
* offset, the frontswap implmentation may either overwrite the data
* and return success or flush the page from frontswap and return failure
*/
int __frontswap_put_page(struct page *page)
{
int ret = -1, dup = 0;
swp_entry_t entry = { .val = page_private(page), };
int type = swp_type(entry);
struct swap_info_struct *sis = swap_info[type];
pgoff_t offset = swp_offset(entry);
BUG_ON(!PageLocked(page));
if (frontswap_test(sis, offset))
dup = 1;
ret = (*frontswap_ops.put_page)(type, offset, page);
if (ret == 0) {
frontswap_set(sis, offset);
frontswap_succ_puts++;
if (!dup)
sis->frontswap_pages++;
} else if (dup) {
/*
failed dup always results in automatic flush of
the (older) page from frontswap
*/
frontswap_clear(sis, offset);
sis->frontswap_pages--;
frontswap_failed_puts++;
} else
frontswap_failed_puts++;
return ret;
}
/*
* Flush any data from frontswap associated with the specified swaptype
* and offset so that a subsequent "get" will fail.
*/
void __frontswap_flush_page(unsigned type, pgoff_t offset)
{
struct swap_info_struct *sis = swap_info[type];
if (frontswap_test(sis, offset)) {
(*frontswap_ops.flush_page)(type, offset);
sis->frontswap_pages--;
frontswap_clear(sis, offset);
frontswap_flushes++;
}
}
/*
* "Get" data from frontswap associated with swaptype and offset that were
* specified when the data was put to frontswap and use it to fill the
* specified page with data. Page must be locked and in the swap cache.
*/
int __frontswap_load(struct page *page)
{
int ret = -1;
swp_entry_t entry = { .val = page_private(page), };
int type = swp_type(entry);
struct swap_info_struct *sis = swap_info[type];
pgoff_t offset = swp_offset(entry);
BUG_ON(!PageLocked(page));
BUG_ON(sis == NULL);
if (frontswap_test(sis, offset))
ret = frontswap_ops.load(type, offset, page);
if (ret == 0) {
inc_frontswap_loads();
if (frontswap_tmem_exclusive_gets_enabled) {
SetPageDirty(page);
frontswap_clear(sis, offset);
}
}
return ret;
}
static inline void __frontswap_clear(struct swap_info_struct *sis, pgoff_t offset)
{
frontswap_clear(sis, offset);
atomic_dec(&sis->frontswap_pages);
}