fs: dcache scale dentry refcount
Make d_count non-atomic and protect it with d_lock. This allows us to ensure a
0 refcount dentry remains 0 without dcache_lock. It is also fairly natural when
we start protecting many other dentry members with d_lock.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 9184c7c..12de824 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1720,7 +1720,7 @@
spin_lock(&dcache_lock);
spin_lock(&dentry->d_lock);
- if (atomic_read(&dentry->d_count) > 1) {
+ if (dentry->d_count > 1) {
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
/* Start asynchronous writeout of the inode */
@@ -1868,7 +1868,7 @@
dfprintk(VFS, "NFS: rename(%s/%s -> %s/%s, ct=%d)\n",
old_dentry->d_parent->d_name.name, old_dentry->d_name.name,
new_dentry->d_parent->d_name.name, new_dentry->d_name.name,
- atomic_read(&new_dentry->d_count));
+ new_dentry->d_count);
/*
* For non-directories, check whether the target is busy and if so,
@@ -1886,7 +1886,7 @@
rehash = new_dentry;
}
- if (atomic_read(&new_dentry->d_count) > 2) {
+ if (new_dentry->d_count > 2) {
int err;
/* copy the target dentry's name */
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index 7bdec85..8fe9eb4 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -496,7 +496,7 @@
dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n",
dentry->d_parent->d_name.name, dentry->d_name.name,
- atomic_read(&dentry->d_count));
+ dentry->d_count);
nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
/*