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mm: frontswap: split out __frontswap_unuse_pages 

An attempt at making frontswap_shrink shorter and more readable. This patch
splits out walking through the swap list to find an entry with enough
pages to unuse.

Also, assert that the internal __frontswap_unuse_pages is called under swap
lock, since that part of code was previously directly happen inside the lock.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Sasha Levin 2012-06-10 12:51:02 +02:00 committed by Konrad Rzeszutek Wilk
parent 96253444db
commit f116695a50
1 changed files with 39 additions and 20 deletions
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59
mm/frontswap.c
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@ -230,6 +230,41 @@ static unsigned long __frontswap_curr_pages(void)
return totalpages;
}
static int __frontswap_unuse_pages(unsigned long total, unsigned long *unused,
int *swapid)
{
int ret = -EINVAL;
struct swap_info_struct *si = NULL;
int si_frontswap_pages;
unsigned long total_pages_to_unuse = total;
unsigned long pages = 0, pages_to_unuse = 0;
int type;
assert_spin_locked(&swap_lock);
for (type = swap_list.head; type >= 0; type = si->next) {
si = swap_info[type];
si_frontswap_pages = atomic_read(&si->frontswap_pages);
if (total_pages_to_unuse < si_frontswap_pages) {
pages = pages_to_unuse = total_pages_to_unuse;
} else {
pages = si_frontswap_pages;
pages_to_unuse = 0; /* unuse all */
}
/* ensure there is enough RAM to fetch pages from frontswap */
if (security_vm_enough_memory_mm(current->mm, pages)) {
ret = -ENOMEM;
continue;
}
vm_unacct_memory(pages);
*unused = pages_to_unuse;
*swapid = type;
ret = 0;
break;
}
return ret;
}
/*
* Frontswap, like a true swap device, may unnecessarily retain pages
* under certain circumstances; "shrink" frontswap is essentially a
@ -240,11 +275,9 @@ static unsigned long __frontswap_curr_pages(void)
*/
void frontswap_shrink(unsigned long target_pages)
{
struct swap_info_struct *si = NULL;
int si_frontswap_pages;
unsigned long total_pages = 0, total_pages_to_unuse;
unsigned long pages = 0, pages_to_unuse = 0;
int type;
unsigned long pages_to_unuse = 0;
int type, ret;
bool locked = false;
/*
@ -258,22 +291,8 @@ void frontswap_shrink(unsigned long target_pages)
if (total_pages <= target_pages)
goto out;
total_pages_to_unuse = total_pages - target_pages;
for (type = swap_list.head; type >= 0; type = si->next) {
si = swap_info[type];
si_frontswap_pages = atomic_read(&si->frontswap_pages);
if (total_pages_to_unuse < si_frontswap_pages) {
pages = pages_to_unuse = total_pages_to_unuse;
} else {
pages = si_frontswap_pages;
pages_to_unuse = 0; /* unuse all */
}
/* ensure there is enough RAM to fetch pages from frontswap */
if (security_vm_enough_memory_mm(current->mm, pages))
continue;
vm_unacct_memory(pages);
break;
}
if (type < 0)
ret = __frontswap_unuse_pages(total_pages_to_unuse, &pages_to_unuse, &type);
if (ret < 0)
goto out;
locked = false;
spin_unlock(&swap_lock);