NFS: Convert nfs_attr_generation_counter into an atomic_long
The most important property we need from nfs_attr_generation_counter is
monotonicity, which is not guaranteed by the current system of smp memory
barriers. We should convert it to an atomic_long_t, and drop the memory
barriers.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index dc52793..d22eb38 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -908,21 +908,16 @@
return nfs_size_to_loff_t(fattr->size) > i_size_read(inode);
}
-static unsigned long nfs_attr_generation_counter;
+static atomic_long_t nfs_attr_generation_counter;
static unsigned long nfs_read_attr_generation_counter(void)
{
- smp_rmb();
- return nfs_attr_generation_counter;
+ return atomic_long_read(&nfs_attr_generation_counter);
}
unsigned long nfs_inc_attr_generation_counter(void)
{
- unsigned long ret;
- smp_rmb();
- ret = ++nfs_attr_generation_counter;
- smp_wmb();
- return ret;
+ return atomic_long_inc_return(&nfs_attr_generation_counter);
}
void nfs_fattr_init(struct nfs_fattr *fattr)