From 6ed6decccf544970664757464cfb67e081775e6a Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 10 Apr 2006 22:55:32 -0700 Subject: [PATCH] [PATCH] knfsd: nfsd4: fix corruption of returned data when using 64k pages 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 Signed-off-by: Linus Torvalds --- fs/nfsd/nfs4xdr.c | 42 +++++++++++++++++------------------------- 1 file changed, 17 insertions(+), 25 deletions(-) diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 845f25251d8..f2710cfc0bc 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -2084,27 +2084,20 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_read 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_compoundres *resp, int nfserr, struct nfsd4_r 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; } -- 2.20.1