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>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 9184c7c80f78..12de824edb5c 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1720,7 +1720,7 @@ static int nfs_unlink(struct inode *dir, struct dentry *dentry)
 
         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 @@ static int nfs_rename(struct inode *old_dir, struct dentry *old_dentry,
         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 @@ static int nfs_rename(struct inode *old_dir, struct dentry *old_dentry,
                         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 */