| Message ID | 169583500802.5201.6400721981172612933.stgit@bazille.1015granger.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v1] NFSD: Fix zero NFSv4 READ results when RQ_SPLICE_OK is not set | expand |
On 27/09/2023 20.16, Chuck Lever wrote: > From: Chuck Lever <chuck.lever@oracle.com> > > nfsd4_encode_readv() uses xdr->buf->page_len as a starting point for > the nfsd_iter_read() sink buffer -- page_len is going to be offset > by the parts of the COMPOUND that have already been encoded into > xdr->buf->pages. > > However, that value must be captured /before/ > xdr_reserve_space_vec() advances page_len by the expected size of > the read payload. Otherwise, the whole front part of the first > page of the payload in the reply will be uninitialized. > > Mantas hit this because sec=krb5i forces RQ_SPLICE_OK off, which > invokes the readv part of the nfsd4_encode_read() path. Also, > older Linux NFS clients appear to send shorter READ requests > for files smaller than a page, whereas newer clients just send > page-sized requests and let the server send as many bytes as > are in the file. > > Reported-by: Mantas Mikulėnas <grawity@gmail.com> > Closes: https://lore.kernel.org/linux-nfs/f1d0b234-e650-0f6e-0f5d-126b3d51d1eb@gmail.com/ > Fixes: 703d75215555 ("NFSD: Hoist rq_vec preparation into nfsd_read() [step two]") > Signed-off-by: Chuck Lever <chuck.lever@oracle.com> > --- > fs/nfsd/nfs4xdr.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c > index 2e40c74d2f72..92c7dde148a4 100644 > --- a/fs/nfsd/nfs4xdr.c > +++ b/fs/nfsd/nfs4xdr.c > @@ -4113,6 +4113,7 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp, > struct file *file, unsigned long maxcount) > { > struct xdr_stream *xdr = resp->xdr; > + unsigned int base = xdr->buf->page_len & ~PAGE_MASK; > unsigned int starting_len = xdr->buf->len; > __be32 zero = xdr_zero; > __be32 nfserr; > @@ -4121,8 +4122,7 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp, > return nfserr_resource; > > nfserr = nfsd_iter_read(resp->rqstp, read->rd_fhp, file, > - read->rd_offset, &maxcount, > - xdr->buf->page_len & ~PAGE_MASK, > + read->rd_offset, &maxcount, base, > &read->rd_eof); > read->rd_length = maxcount; > if (nfserr) > Thanks, this seems to work for me.
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 2e40c74d2f72..92c7dde148a4 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -4113,6 +4113,7 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp, struct file *file, unsigned long maxcount) { struct xdr_stream *xdr = resp->xdr; + unsigned int base = xdr->buf->page_len & ~PAGE_MASK; unsigned int starting_len = xdr->buf->len; __be32 zero = xdr_zero; __be32 nfserr; @@ -4121,8 +4122,7 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp, return nfserr_resource; nfserr = nfsd_iter_read(resp->rqstp, read->rd_fhp, file, - read->rd_offset, &maxcount, - xdr->buf->page_len & ~PAGE_MASK, + read->rd_offset, &maxcount, base, &read->rd_eof); read->rd_length = maxcount; if (nfserr)