res_counter: limit change support ebusy

Add an interface to set limit.  This is necessary to memory resource
controller because it shrinks usage at set limit.

Other controllers may not need this interface to shrink usage because
shrinking is not necessary or impossible.

Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
KAMEZAWA Hiroyuki 2008-07-25 01:47:19 -07:00 committed by Linus Torvalds
parent cede86acd8
commit 12b9804419
1 changed files with 16 additions and 0 deletions

View File

@ -158,4 +158,20 @@ static inline void res_counter_reset_failcnt(struct res_counter *cnt)
cnt->failcnt = 0; cnt->failcnt = 0;
spin_unlock_irqrestore(&cnt->lock, flags); spin_unlock_irqrestore(&cnt->lock, flags);
} }
static inline int res_counter_set_limit(struct res_counter *cnt,
unsigned long long limit)
{
unsigned long flags;
int ret = -EBUSY;
spin_lock_irqsave(&cnt->lock, flags);
if (cnt->usage < limit) {
cnt->limit = limit;
ret = 0;
}
spin_unlock_irqrestore(&cnt->lock, flags);
return ret;
}
#endif #endif