NFSD: Return NFS4ERR_FILE_OPEN only when renaming over an open file

RFC 8881 Section 18.26.4 paragraphs 1 - 3 tell us that RENAME should
return NFS4ERR_FILE_OPEN only when the target object is a file that
is currently open. If the target is a directory, some other status
must be returned.

Generally I expect that a delegation recall will be triggered in
some of these circumstances. In other cases, the VFS might return
-EBUSY for other reasons, and NFSD has to ensure that errno does
not leak to clients as a status code that is not permitted by spec.

There are some error flows where the target dentry hasn't been
found yet. The default value for @type therefore is S_IFDIR to return
an alternate status code in those cases.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 4e0a2c0549c793aedb9e1c290f43c62507a06da6..adf092406d79e102e1f0d31d90f4a6aed1f5d4ff 100644 (file)
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1794,9 +1794,19 @@ nfsd_has_cached_files(struct dentry *dentry)
        return ret;
 }
 
-/*
- * Rename a file
- * N.B. After this call _both_ ffhp and tfhp need an fh_put
+/**
+ * nfsd_rename - rename a directory entry
+ * @rqstp: RPC transaction context
+ * @ffhp: the file handle of parent directory containing the entry to be renamed
+ * @fname: the filename of directory entry to be renamed
+ * @flen: the length of @fname in octets
+ * @tfhp: the file handle of parent directory to contain the renamed entry
+ * @tname: the filename of the new entry
+ * @tlen: the length of @tlen in octets
+ *
+ * After this call _both_ ffhp and tfhp need an fh_put.
+ *
+ * Returns a generic NFS status code in network byte-order.
  */
 __be32
 nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
@@ -1804,6 +1814,7 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
 {
        struct dentry   *fdentry, *tdentry, *odentry, *ndentry, *trap;
        struct inode    *fdir, *tdir;
+       int             type = S_IFDIR;
        __be32          err;
        int             host_err;
        bool            close_cached = false;
@@ -1861,11 +1872,14 @@ retry:
        host_err = -EINVAL;
        if (odentry == trap)
                goto out_dput_old;
+       type = d_inode(odentry)->i_mode & S_IFMT;
 
        ndentry = lookup_one_len(tname, tdentry, tlen);
        host_err = PTR_ERR(ndentry);
        if (IS_ERR(ndentry))
                goto out_dput_old;
+       if (d_inode(ndentry))
+               type = d_inode(ndentry)->i_mode & S_IFMT;
        host_err = -ENOTEMPTY;
        if (ndentry == trap)
                goto out_dput_new;
@@ -1903,7 +1917,18 @@ retry:
  out_dput_old:
        dput(odentry);
  out_nfserr:
-       err = nfserrno(host_err);
+       if (host_err == -EBUSY) {
+               /*
+                * See RFC 8881 Section 18.26.4 para 1-3: NFSv4 RENAME
+                * wants a status unique to the object type.
+                */
+               if (type != S_IFDIR)
+                       err = nfserr_file_open;
+               else
+                       err = nfserr_acces;
+       } else {
+               err = nfserrno(host_err);
+       }
 
        if (!close_cached) {
                fh_fill_post_attrs(ffhp);