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, 2 insertions, 3 deletions

diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 0f33e621892f..ddf5d75e97a2 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -793,9 +793,8 @@ struct nfs_rpc_ops {
         int     (*rename)  (struct inode *, struct qstr *,
                             struct inode *, struct qstr *);
         int     (*link)    (struct inode *, struct inode *, struct qstr *);
-        int     (*symlink) (struct inode *, struct qstr *, struct qstr *,
-                            struct iattr *, struct nfs_fh *,
-                            struct nfs_fattr *);
+        int     (*symlink) (struct inode *, struct dentry *, struct qstr *,
+                            struct iattr *);
         int     (*mkdir)   (struct inode *, struct dentry *, struct iattr *);
         int     (*rmdir)   (struct inode *, struct qstr *);
         int     (*readdir) (struct dentry *, struct rpc_cred *,