NFSv4: Fix a readdir regression

Commit 7ebb9315 (NFS: use secinfo when crossing mountpoints) introduces
a regression when decoding an NFSv4 readdir entry that sets the
rdattr_error field.
By treating the resulting value as if it is a decoding error, the current
code may cause us to skip valid readdir entries.

Reported-by: Andy Adamson <andros@netapp.com>
Cc: stable@kernel.org [2.6.39]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index c4b7d6c..5db44a8 100644 (file)
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -3098,7 +3098,7 @@ out_overflow:
        return -EIO;
 }
 
-static int decode_attr_error(struct xdr_stream *xdr, uint32_t *bitmap)
+static int decode_attr_error(struct xdr_stream *xdr, uint32_t *bitmap, int32_t *res)
 {
        __be32 *p;
 
@@ -3109,7 +3109,7 @@ static int decode_attr_error(struct xdr_stream *xdr, uint32_t *bitmap)
                if (unlikely(!p))
                        goto out_overflow;
                bitmap[0] &= ~FATTR4_WORD0_RDATTR_ERROR;
-               return -be32_to_cpup(p);
+               *res = -be32_to_cpup(p);
        }
        return 0;
 out_overflow:
@@ -4070,6 +4070,7 @@ static int decode_getfattr_attrs(struct xdr_stream *xdr, uint32_t *bitmap,
        int status;
        umode_t fmode = 0;
        uint32_t type;
+       int32_t err;
 
        status = decode_attr_type(xdr, bitmap, &type);
        if (status < 0)
@@ -4095,13 +4096,12 @@ static int decode_getfattr_attrs(struct xdr_stream *xdr, uint32_t *bitmap,
                goto xdr_error;
        fattr->valid |= status;
 
-       status = decode_attr_error(xdr, bitmap);
-       if (status == -NFS4ERR_WRONGSEC) {
-               nfs_fixup_secinfo_attributes(fattr, fh);
-               status = 0;
-       }
+       err = 0;
+       status = decode_attr_error(xdr, bitmap, &err);
        if (status < 0)
                goto xdr_error;
+       if (err == -NFS4ERR_WRONGSEC)
+               nfs_fixup_secinfo_attributes(fattr, fh);
 
        status = decode_attr_filehandle(xdr, bitmap, fh);
        if (status < 0)