[PATCH] knfsd: nfsd4: fix corruption on readdir encoding with 64k pages

Fix corruption on readdir encoding with 64k pages.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 7 deletions

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index f2710cfc0bc5..de3998f15f10 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2157,7 +2157,7 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_re
 {
         int maxcount;
         loff_t offset;
-        u32 *page, *savep;
+        u32 *page, *savep, *tailbase;
         ENCODE_HEAD;
 
         if (nfserr)
@@ -2173,6 +2173,7 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_re
         WRITE32(0);
         ADJUST_ARGS();
         resp->xbuf->head[0].iov_len = ((char*)resp->p) - (char*)resp->xbuf->head[0].iov_base;
+        tailbase = p;
 
         maxcount = PAGE_SIZE;
         if (maxcount > readdir->rd_maxcount)
@@ -2217,14 +2218,12 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_re
         *p++ = htonl(readdir->common.err == nfserr_eof);
         resp->xbuf->page_len = ((char*)p) - (char*)page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused-1]);
 
-        /* allocate a page for the tail */
-        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 = tailbase;
         resp->xbuf->tail[0].iov_len = 0;
         resp->p = resp->xbuf->tail[0].iov_base;
-        resp->end = resp->p + PAGE_SIZE/4;
+        resp->end = resp->p + (PAGE_SIZE - resp->xbuf->head[0].iov_len)/4;
 
         return 0;
 err_no_verf: