NFS: Fix double d_drop in nfs_instantiate() error path

If the LOOKUP or GETATTR in nfs_instantiate fail, nfs_instantiate will do a
d_drop before returning.  But some callers already do a d_drop in the case
of an error return.  Make certain we do only one d_drop in all error paths.

This issue was introduced because over time, the symlink proc API diverged
slightly from the create/mkdir/mknod proc API.  To prevent other coding
mistakes of this type, change the symlink proc API to be more like
create/mkdir/mknod and move the nfs_instantiate call into the symlink proc
routines so it is used in exactly the same way for create, mkdir, mknod,
and symlink.

Test plan:
Connectathon, all versions of NFS.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 4 insertions, 12 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 084e8cb41c84..affd3ae52e55 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1147,23 +1147,20 @@ int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
                 struct inode *dir = dentry->d_parent->d_inode;
                 error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr);
                 if (error)
-                        goto out_err;
+                        return error;
         }
         if (!(fattr->valid & NFS_ATTR_FATTR)) {
                 struct nfs_server *server = NFS_SB(dentry->d_sb);
                 error = server->nfs_client->rpc_ops->getattr(server, fhandle, fattr);
                 if (error < 0)
-                        goto out_err;
+                        return error;
         }
         inode = nfs_fhget(dentry->d_sb, fhandle, fattr);
         error = PTR_ERR(inode);
         if (IS_ERR(inode))
-                goto out_err;
+                return error;
         d_instantiate(dentry, inode);
         return 0;
-out_err:
-        d_drop(dentry);
-        return error;
 }
 
 /*
@@ -1448,8 +1445,6 @@ static int
 nfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
 {
         struct iattr attr;
-        struct nfs_fattr sym_attr;
-        struct nfs_fh sym_fh;
         struct qstr qsymname;
         int error;
 
@@ -1473,12 +1468,9 @@ dentry->d_parent->d_name.name, dentry->d_name.name);
 
         lock_kernel();
         nfs_begin_data_update(dir);
-        error = NFS_PROTO(dir)->symlink(dir, &dentry->d_name, &qsymname,
-                                          &attr, &sym_fh, &sym_attr);
+        error = NFS_PROTO(dir)->symlink(dir, dentry, &qsymname, &attr);
         nfs_end_data_update(dir);
         if (!error)
-                error = nfs_instantiate(dentry, &sym_fh, &sym_attr);
-        else
                 d_drop(dentry);
         unlock_kernel();
         return error;