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Commit 54af6233 authored by Nick Piggin's avatar Nick Piggin Committed by Dave Kleikamp
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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: default avatarNick Piggin <npiggin@suse.de>
Signed-off-by: default avatarDave Kleikamp <shaggy@linux.vnet.ibm.com>
parent 67e6682f

fs/jfs/jfs_metapage.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

}