nfsd4: fix xdr decoding of large non-write compounds

This fixes a regression from 247500820ebd02ad87525db5d9b199e5b66f6636
"nfsd4: fix decoding of compounds across page boundaries".  The previous
code was correct: argp->pagelist is initialized in
nfs4svc_deocde_compoundargs to rqstp->rq_arg.pages, and is therefore a
pointer to the page *after* the page we are currently decoding.

The reason that patch nevertheless fixed a problem with decoding
compounds containing write was a bug in the write decoding introduced by
5a80a54d21c96590d013378d8c5f65f879451ab4 "nfsd4: reorganize write
decoding", after which write decoding no longer adhered to the rule that
argp->pagelist point to the next page.

Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 088de1355e930c05fd9dd9c03bb3710b7531fed7..ee7237f99f54cd413dba6375dbc344084d0ece56 100644 (file)
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -141,8 +141,8 @@ xdr_error:                                  \
 
 static void next_decode_page(struct nfsd4_compoundargs *argp)
 {
-       argp->pagelist++;
        argp->p = page_address(argp->pagelist[0]);
+       argp->pagelist++;
        if (argp->pagelen < PAGE_SIZE) {
                argp->end = argp->p + (argp->pagelen>>2);
                argp->pagelen = 0;
@@ -1229,6 +1229,7 @@ nfsd4_decode_write(struct nfsd4_compoundargs *argp, struct nfsd4_write *write)
                len -= pages * PAGE_SIZE;
 
                argp->p = (__be32 *)page_address(argp->pagelist[0]);
+               argp->pagelist++;
                argp->end = argp->p + XDR_QUADLEN(PAGE_SIZE);
        }
        argp->p += XDR_QUADLEN(len);