Commit 54af6233 authored Nov 26, 2007 by Nick Piggin Committed by Dave Kleikamp Jan 03, 2008

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>

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);
		}

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