From: NeilBrown In v4 we grab an extra page just for the padding of returned data. The formula that the rpc server uses to allocate pages for the response doesn't take into account this extra page. Instead of adjusting those formulae, we adopt the same solution as v2 and v3, and put the "tail" data in the same page as the "head" data. Signed-off-by: J. Bruce Fields Signed-off-by: Neil Brown Signed-off-by: Andrew Morton --- fs/nfsd/nfs4xdr.c | 42 +++++++++++++++++------------------------- 1 files changed, 17 insertions(+), 25 deletions(-) diff -puN fs/nfsd/nfs4xdr.c~knfsd-nfsd4-fix-corruption-of-returned-data-when-using-64k-pages fs/nfsd/nfs4xdr.c --- 25/fs/nfsd/nfs4xdr.c~knfsd-nfsd4-fix-corruption-of-returned-data-when-using-64k-pages Mon Apr 3 16:08:08 2006 +++ 25-akpm/fs/nfsd/nfs4xdr.c Mon Apr 3 16:08:08 2006 @@ -2084,27 +2084,20 @@ nfsd4_encode_read(struct nfsd4_compoundr WRITE32(eof); WRITE32(maxcount); ADJUST_ARGS(); - resp->xbuf->head[0].iov_len = ((char*)resp->p) - (char*)resp->xbuf->head[0].iov_base; - + resp->xbuf->head[0].iov_len = (char*)p + - (char*)resp->xbuf->head[0].iov_base; resp->xbuf->page_len = maxcount; - /* read zero bytes -> don't set up tail */ - if(!maxcount) - return 0; - - /* set up page for remaining responses */ - svc_take_page(resp->rqstp); - resp->xbuf->tail[0].iov_base = - page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused-1]); - resp->rqstp->rq_restailpage = resp->rqstp->rq_resused-1; + /* Use rest of head for padding and remaining ops: */ + resp->rqstp->rq_restailpage = 0; + resp->xbuf->tail[0].iov_base = p; resp->xbuf->tail[0].iov_len = 0; - resp->p = resp->xbuf->tail[0].iov_base; - resp->end = resp->p + PAGE_SIZE/4; - if (maxcount&3) { - *(resp->p)++ = 0; + RESERVE_SPACE(4); + WRITE32(0); resp->xbuf->tail[0].iov_base += maxcount&3; resp->xbuf->tail[0].iov_len = 4 - (maxcount&3); + ADJUST_ARGS(); } return 0; } @@ -2141,21 +2134,20 @@ nfsd4_encode_readlink(struct nfsd4_compo WRITE32(maxcount); ADJUST_ARGS(); - resp->xbuf->head[0].iov_len = ((char*)resp->p) - (char*)resp->xbuf->head[0].iov_base; + resp->xbuf->head[0].iov_len = (char*)p + - (char*)resp->xbuf->head[0].iov_base; + resp->xbuf->page_len = maxcount; - svc_take_page(resp->rqstp); - resp->xbuf->tail[0].iov_base = - page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused-1]); - resp->rqstp->rq_restailpage = resp->rqstp->rq_resused-1; + /* Use rest of head for padding and remaining ops: */ + resp->rqstp->rq_restailpage = 0; + resp->xbuf->tail[0].iov_base = p; resp->xbuf->tail[0].iov_len = 0; - resp->p = resp->xbuf->tail[0].iov_base; - resp->end = resp->p + PAGE_SIZE/4; - - resp->xbuf->page_len = maxcount; if (maxcount&3) { - *(resp->p)++ = 0; + RESERVE_SPACE(4); + WRITE32(0); resp->xbuf->tail[0].iov_base += maxcount&3; resp->xbuf->tail[0].iov_len = 4 - (maxcount&3); + ADJUST_ARGS(); } return 0; } _