nfsd4: reserve space before inlining 0-copy pages
Once we've included page-cache pages in the encoding it's difficult to
remove them and restart encoding. (xdr_truncate_encode doesn't handle
that case.) So, make sure we'll have adequate space to finish the
operation first.
For now COMPOUND_SLACK_SPACE checks should prevent this case happening,
but we want to remove those checks.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 799a904..8728715 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3071,6 +3071,10 @@
if (!p)
return nfserr_resource;
+ /* Make sure there will be room for padding if needed: */
+ if (xdr->end - xdr->p < 1)
+ return nfserr_resource;
+
maxcount = svc_max_payload(resp->rqstp);
if (maxcount > read->rd_length)
maxcount = read->rd_length;
@@ -3122,8 +3126,6 @@
resp->xdr.buf->tail[0].iov_len = 0;
if (maxcount&3) {
p = xdr_reserve_space(xdr, 4);
- if (!p)
- return nfserr_resource;
WRITE32(0);
resp->xdr.buf->tail[0].iov_base += maxcount&3;
resp->xdr.buf->tail[0].iov_len = 4 - (maxcount&3);
@@ -3156,6 +3158,9 @@
if (!p)
return nfserr_resource;
+ if (xdr->end - xdr->p < 1)
+ return nfserr_resource;
+
/*
* XXX: By default, the ->readlink() VFS op will truncate symlinks
* if they would overflow the buffer. Is this kosher in NFSv4? If
@@ -3182,8 +3187,6 @@
resp->xdr.buf->tail[0].iov_len = 0;
if (maxcount&3) {
p = xdr_reserve_space(xdr, 4);
- if (!p)
- return nfserr_resource;
WRITE32(0);
resp->xdr.buf->tail[0].iov_base += maxcount&3;
resp->xdr.buf->tail[0].iov_len = 4 - (maxcount&3);
