From: Nick Piggin trylock_buffer and unlock_buffer open and close a critical section. Hence, we can use the lock bitops to get the desired memory ordering. Signed-off-by: Nick Piggin Signed-off-by: Andrew Morton --- fs/buffer.c | 3 +-- include/linux/buffer_head.h | 2 +- 2 files changed, 2 insertions(+), 3 deletions(-) diff -puN fs/buffer.c~fs-buffer-lock-use-lock-bitops fs/buffer.c --- a/fs/buffer.c~fs-buffer-lock-use-lock-bitops +++ a/fs/buffer.c @@ -76,8 +76,7 @@ EXPORT_SYMBOL(__lock_buffer); void unlock_buffer(struct buffer_head *bh) { - smp_mb__before_clear_bit(); - clear_buffer_locked(bh); + clear_bit_unlock(BH_Lock, &bh->b_state); smp_mb__after_clear_bit(); wake_up_bit(&bh->b_state, BH_Lock); } diff -puN include/linux/buffer_head.h~fs-buffer-lock-use-lock-bitops include/linux/buffer_head.h --- a/include/linux/buffer_head.h~fs-buffer-lock-use-lock-bitops +++ a/include/linux/buffer_head.h @@ -322,7 +322,7 @@ static inline void wait_on_buffer(struct static inline int trylock_buffer(struct buffer_head *bh) { - return likely(!test_and_set_bit(BH_Lock, &bh->b_state)); + return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state)); } static inline void lock_buffer(struct buffer_head *bh) _