NFSv4: include bitmap in nfsv4 get acl data

The NFSv4 bitmap size is unbounded: a server can return an arbitrary
sized bitmap in an FATTR4_WORD0_ACL request.  Replace using the
nfs4_fattr_bitmap_maxsz as a guess to the maximum bitmask returned by a server
with the inclusion of the bitmap (xdr length plus bitmasks) and the acl data
xdr length to the (cached) acl page data.

This is a general solution to commit e5012d1f "NFSv4.1: update
nfs4_fattr_bitmap_maxsz" and fixes hitting a BUG_ON in xdr_shrink_bufhead
when getting ACLs.

Fix a bug in decode_getacl that returned -EINVAL on ACLs > page when getxattr
was called with a NULL buffer, preventing ACL > PAGE_SIZE from being retrieved.

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

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 2a7c533be5dd..6c898afe6095 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -602,11 +602,16 @@ struct nfs_getaclargs {
         size_t                          acl_len;
         unsigned int                    acl_pgbase;
         struct page **                  acl_pages;
+        struct page *                   acl_scratch;
         struct nfs4_sequence_args       seq_args;
 };
 
+/* getxattr ACL interface flags */
+#define NFS4_ACL_LEN_REQUEST    0x0001  /* zero length getxattr buffer */
 struct nfs_getaclres {
         size_t                          acl_len;
+        size_t                          acl_data_offset;
+        int                             acl_flags;
         struct nfs4_sequence_res        seq_res;
 };