nfsd4: return nfserr_symlink on v4 OPEN of non-regular file

Without this, an attempt to open a device special file without first
stat'ing it will fail.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 9bf0a6625187..d784ceb81a62 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -168,6 +168,24 @@ do_open_permission(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfs
         return status;
 }
 
+static __be32 nfsd_check_obj_isreg(struct svc_fh *fh)
+{
+        umode_t mode = fh->fh_dentry->d_inode->i_mode;
+
+        if (S_ISREG(mode))
+                return nfs_ok;
+        if (S_ISDIR(mode))
+                return nfserr_isdir;
+        /*
+         * Using err_symlink as our catch-all case may look odd; but
+         * there's no other obvious error for this case in 4.0, and we
+         * happen to know that it will cause the linux v4 client to do
+         * the right thing on attempts to open something other than a
+         * regular file.
+         */
+        return nfserr_symlink;
+}
+
 static __be32
 do_open_lookup(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_open *open)
 {
@@ -216,6 +234,9 @@ do_open_lookup(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_o
                 status = nfsd_lookup(rqstp, current_fh,
                                      open->op_fname.data, open->op_fname.len, &resfh);
                 fh_unlock(current_fh);
+                if (status)
+                        goto out;
+                status = nfsd_check_obj_isreg(&resfh);
         }
         if (status)
                 goto out;