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, 2 insertions, 3 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 184938fcff04..3a359023c9f7 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1756,8 +1756,7 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
                 goto out_dput_new;
 
         if (svc_msnfs(ffhp) &&
-                ((atomic_read(&odentry->d_count) > 1)
-                 || (atomic_read(&ndentry->d_count) > 1))) {
+                ((odentry->d_count > 1) || (ndentry->d_count > 1))) {
                         host_err = -EPERM;
                         goto out_dput_new;
         }
@@ -1843,7 +1842,7 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
         if (type != S_IFDIR) { /* It's UNLINK */
 #ifdef MSNFS
                 if ((fhp->fh_export->ex_flags & NFSEXP_MSNFS) &&
-                        (atomic_read(&rdentry->d_count) > 1)) {
+                        (rdentry->d_count > 1)) {
                         host_err = -EPERM;
                 } else
 #endif