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JFS is missing a memory barrier 

JFS is missing a memory barrier needed to close the critical section before
clearing the lock bit. Use lock bitops for this.

unlock_page() has a second barrier after clearing the lock, which is
required because it checks whether the waitqueue is active without locks.
Such a barrier is not required here because the waitqueue spinlock is
always taken (something to think about if performance is an issue).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
This commit is contained in:
Nick Piggin 2007-11-26 14:58:10 -06:00 committed by Dave Kleikamp
parent 67e6682f18
commit 54af6233d1
1 changed files with 2 additions and 2 deletions
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4
fs/jfs/jfs_metapage.c
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@ -39,11 +39,11 @@ static struct {
#endif
#define metapage_locked(mp) test_bit(META_locked, &(mp)->flag)
#define trylock_metapage(mp) test_and_set_bit(META_locked, &(mp)->flag)
#define trylock_metapage(mp) test_and_set_bit_lock(META_locked, &(mp)->flag)
static inline void unlock_metapage(struct metapage *mp)
{
clear_bit(META_locked, &mp->flag);
clear_bit_unlock(META_locked, &mp->flag);
wake_up(&mp->wait);
}