On Thu, 2020-11-19 at 09:31 -0500, Chuck Lever wrote: > > > > On Nov 19, 2020, at 9:30 AM, Trond Myklebust < > > trondmy@xxxxxxxxxxxxxxx> wrote: > > > > On Thu, 2020-11-19 at 09:17 -0500, Chuck Lever wrote: > > > > > > > > > > On Nov 18, 2020, at 5:19 PM, trondmy@xxxxxxxxxx wrote: > > > > > > > > From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> > > > > > > > > When doing a read() into a page, we also don't care if the nul > > > > padding > > > > stays in that last page when the data length is not 32-bit > > > > aligned. > > > > > > What if the READ payload lands in the middle of a file? The > > > pad on the end will overwrite file content just past where > > > the READ payload lands. > > > > If the size > buf->page_len, then it gets truncated in > > xdr_align_pages() afaik. > > I will need to check how RPC/RDMA behaves. It might build a > chunk that includes the pad in this case, which would break > things. That would be a bug in the existing code too, then. It shouldn't be writing beyond the buffer size we set in the NFS layer. > > > > Signed-off-by: Trond Myklebust > > > > <trond.myklebust@xxxxxxxxxxxxxxx> > > > > --- > > > > fs/nfs/nfs2xdr.c | 2 +- > > > > fs/nfs/nfs3xdr.c | 2 +- > > > > fs/nfs/nfs4xdr.c | 2 +- > > > > 3 files changed, 3 insertions(+), 3 deletions(-) > > > > > > > > diff --git a/fs/nfs/nfs2xdr.c b/fs/nfs/nfs2xdr.c > > > > index db9c265ad9e1..468bfbfe44d7 100644 > > > > --- a/fs/nfs/nfs2xdr.c > > > > +++ b/fs/nfs/nfs2xdr.c > > > > @@ -102,7 +102,7 @@ static int decode_nfsdata(struct xdr_stream > > > > *xdr, struct nfs_pgio_res *result) > > > > if (unlikely(!p)) > > > > return -EIO; > > > > count = be32_to_cpup(p); > > > > - recvd = xdr_read_pages(xdr, count); > > > > + recvd = xdr_read_pages(xdr, xdr_align_size(count)); > > > > if (unlikely(count > recvd)) > > > > goto out_cheating; > > > > out: > > > > diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c > > > > index d3e1726d538b..8ef7c961d3e2 100644 > > > > --- a/fs/nfs/nfs3xdr.c > > > > +++ b/fs/nfs/nfs3xdr.c > > > > @@ -1611,7 +1611,7 @@ static int decode_read3resok(struct > > > > xdr_stream *xdr, > > > > ocount = be32_to_cpup(p++); > > > > if (unlikely(ocount != count)) > > > > goto out_mismatch; > > > > - recvd = xdr_read_pages(xdr, count); > > > > + recvd = xdr_read_pages(xdr, xdr_align_size(count)); > > > > if (unlikely(count > recvd)) > > > > goto out_cheating; > > > > out: > > > > diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c > > > > index 755b556e85c3..5baa767106dc 100644 > > > > --- a/fs/nfs/nfs4xdr.c > > > > +++ b/fs/nfs/nfs4xdr.c > > > > @@ -5202,7 +5202,7 @@ static int decode_read(struct xdr_stream > > > > *xdr, struct rpc_rqst *req, > > > > return -EIO; > > > > eof = be32_to_cpup(p++); > > > > count = be32_to_cpup(p); > > > > - recvd = xdr_read_pages(xdr, count); > > > > + recvd = xdr_read_pages(xdr, xdr_align_size(count)); > > > > if (count > recvd) { > > > > dprintk("NFS: server cheating in read reply: " > > > > "count %u > recvd %u\n", count, > > > > recvd); > > > > -- > > > > 2.28.0 -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@xxxxxxxxxxxxxxx