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Subject: Re: [PATCH v1 20/23] NFS: Account for XDR pad of buf->pages
From:   Chuck Lever <chuck.lever@oracle.com>
In-Reply-To: <CAN-5tyHSH75TVSok+RXdXoq6bOVse__E4AMCzuSnmYrTgzH_Vg@mail.gmail.com>
Date:   Fri, 5 Apr 2019 15:23:19 -0400
Cc:     Anna Schumaker <anna.schumaker@netapp.com>,
        linux-rdma <linux-rdma@vger.kernel.org>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
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Message-Id: <5AC0653D-3D4E-4C0C-BFE3-616BF32589CB@oracle.com>
References: <20190211161920.2817.20881.stgit@manet.1015granger.net>
 <20190211162525.2817.60645.stgit@manet.1015granger.net>
 <CAN-5tyH1zAuW7AxoZc+psRWWQT0S9J3wDu+iDgLg4=qGTvUufA@mail.gmail.com>
 <0157F163-7554-413C-ACCA-FE6646C04716@oracle.com>
 <CAN-5tyHSH75TVSok+RXdXoq6bOVse__E4AMCzuSnmYrTgzH_Vg@mail.gmail.com>
To:     Olga Kornievskaia <aglo@umich.edu>
Sender: linux-nfs-owner@vger.kernel.org
Precedence: bulk


> On Apr 5, 2019, at 3:17 PM, Olga Kornievskaia <aglo@umich.edu> wrote:
>=20
> On Fri, Apr 5, 2019 at 1:51 PM Chuck Lever <chuck.lever@oracle.com> =
wrote:
>>=20
>>=20
>>=20
>>> On Apr 5, 2019, at 1:36 PM, Olga Kornievskaia <aglo@umich.edu> =
wrote:
>>>=20
>>> Hi Chuck,
>>>=20
>>> This patch break ACLs. After applying this patch nfs4_getfacl fails
>>> (it fails within xdr and returns ENOTSUPP). Any ideas why?
>>=20
>> Possibly the macro that defines the maximum size of the reply
>> is incorrect.
>>=20
>=20
> This also breaks FS_LOCATION. I'm going to go on the limb here and say
> that it probably breaks whatever else it modified.

It modifies READ, READDIR, and READLINK. Are those broken?


> The question is: can't we just revert it??

Why not "root cause" it first?


>>> On Mon, Feb 11, 2019 at 11:25 AM Chuck Lever =
<chuck.lever@oracle.com> wrote:
>>>>=20
>>>> Certain NFS results (eg. READLINK) might expect a data payload that
>>>> is not an exact multiple of 4 bytes. In this case, XDR encoding
>>>> is required to pad that payload so its length on the wire is a
>>>> multiple of 4 bytes. The constants that define the maximum size of
>>>> each NFS result do not appear to account for this extra word.
>>>>=20
>>>> In each case where the data payload is to be received into pages:
>>>>=20
>>>> - 1 word is added to the size of the receive buffer allocated by
>>>> call_allocate
>>>>=20
>>>> - rpc_inline_rcv_pages subtracts 1 word from @hdrsize so that the
>>>> extra buffer space falls into the rcv_buf's tail iovec
>>>>=20
>>>> - If buf->pagelen is word-aligned, an XDR pad is not needed and
>>>> is thus removed from the tail
>>>>=20
>>>> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
>>>> ---
>>>> fs/nfs/nfs2xdr.c  |    6 +++---
>>>> fs/nfs/nfs3xdr.c  |   10 +++++-----
>>>> fs/nfs/nfs4xdr.c  |   15 ++++++++-------
>>>> net/sunrpc/clnt.c |    6 +++++-
>>>> net/sunrpc/xdr.c  |    2 ++
>>>> 5 files changed, 23 insertions(+), 16 deletions(-)
>>>>=20
>>>> diff --git a/fs/nfs/nfs2xdr.c b/fs/nfs/nfs2xdr.c
>>>> index 1dcd0fe..a7ed29d 100644
>>>> --- a/fs/nfs/nfs2xdr.c
>>>> +++ b/fs/nfs/nfs2xdr.c
>>>> @@ -56,11 +56,11 @@
>>>>=20
>>>> #define NFS_attrstat_sz                (1+NFS_fattr_sz)
>>>> #define NFS_diropres_sz                =
(1+NFS_fhandle_sz+NFS_fattr_sz)
>>>> -#define NFS_readlinkres_sz     (2)
>>>> -#define NFS_readres_sz         (1+NFS_fattr_sz+1)
>>>> +#define NFS_readlinkres_sz     (2+1)
>>>> +#define NFS_readres_sz         (1+NFS_fattr_sz+1+1)
>>>> #define NFS_writeres_sz         (NFS_attrstat_sz)
>>>> #define NFS_stat_sz            (1)
>>>> -#define NFS_readdirres_sz      (1)
>>>> +#define NFS_readdirres_sz      (1+1)
>>>> #define NFS_statfsres_sz       (1+NFS_info_sz)
>>>>=20
>>>> static int nfs_stat_to_errno(enum nfs_stat);
>>>> diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
>>>> index a54dcf4..110358f 100644
>>>> --- a/fs/nfs/nfs3xdr.c
>>>> +++ b/fs/nfs/nfs3xdr.c
>>>> @@ -69,13 +69,13 @@
>>>> #define NFS3_removeres_sz      (NFS3_setattrres_sz)
>>>> #define NFS3_lookupres_sz      (1+NFS3_fh_sz+(2 * =
NFS3_post_op_attr_sz))
>>>> #define NFS3_accessres_sz      (1+NFS3_post_op_attr_sz+1)
>>>> -#define NFS3_readlinkres_sz    (1+NFS3_post_op_attr_sz+1)
>>>> -#define NFS3_readres_sz                (1+NFS3_post_op_attr_sz+3)
>>>> +#define NFS3_readlinkres_sz    (1+NFS3_post_op_attr_sz+1+1)
>>>> +#define NFS3_readres_sz                =
(1+NFS3_post_op_attr_sz+3+1)
>>>> #define NFS3_writeres_sz       (1+NFS3_wcc_data_sz+4)
>>>> #define NFS3_createres_sz      =
(1+NFS3_fh_sz+NFS3_post_op_attr_sz+NFS3_wcc_data_sz)
>>>> #define NFS3_renameres_sz      (1+(2 * NFS3_wcc_data_sz))
>>>> #define NFS3_linkres_sz                =
(1+NFS3_post_op_attr_sz+NFS3_wcc_data_sz)
>>>> -#define NFS3_readdirres_sz     (1+NFS3_post_op_attr_sz+2)
>>>> +#define NFS3_readdirres_sz     (1+NFS3_post_op_attr_sz+2+1)
>>>> #define NFS3_fsstatres_sz      (1+NFS3_post_op_attr_sz+13)
>>>> #define NFS3_fsinfores_sz      (1+NFS3_post_op_attr_sz+12)
>>>> #define NFS3_pathconfres_sz    (1+NFS3_post_op_attr_sz+6)
>>>> @@ -85,7 +85,7 @@
>>>> #define ACL3_setaclargs_sz     (NFS3_fh_sz+1+ \
>>>>                               XDR_QUADLEN(NFS_ACL_INLINE_BUFSIZE))
>>>> #define ACL3_getaclres_sz      (1+NFS3_post_op_attr_sz+1+ \
>>>> -                               =
XDR_QUADLEN(NFS_ACL_INLINE_BUFSIZE))
>>>> +                               =
XDR_QUADLEN(NFS_ACL_INLINE_BUFSIZE)+1)
>>>> #define ACL3_setaclres_sz      (1+NFS3_post_op_attr_sz)
>>>>=20
>>>> static int nfs3_stat_to_errno(enum nfs_stat);
>>>> @@ -1629,7 +1629,7 @@ static int nfs3_xdr_dec_read3res(struct =
rpc_rqst *req, struct xdr_stream *xdr,
>>>>       result->op_status =3D status;
>>>>       if (status !=3D NFS3_OK)
>>>>               goto out_status;
>>>> -       result->replen =3D 3 + ((xdr_stream_pos(xdr) - pos) >> 2);
>>>> +       result->replen =3D 4 + ((xdr_stream_pos(xdr) - pos) >> 2);
>>>>       error =3D decode_read3resok(xdr, result);
>>>> out:
>>>>       return error;
>>>> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
>>>> index d0fa18d..6d9d5e2 100644
>>>> --- a/fs/nfs/nfs4xdr.c
>>>> +++ b/fs/nfs/nfs4xdr.c
>>>> @@ -215,14 +215,14 @@ static int decode_layoutget(struct xdr_stream =
*xdr, struct rpc_rqst *req,
>>>>                                nfs4_fattr_bitmap_maxsz)
>>>> #define encode_read_maxsz      (op_encode_hdr_maxsz + \
>>>>                                encode_stateid_maxsz + 3)
>>>> -#define decode_read_maxsz      (op_decode_hdr_maxsz + 2)
>>>> +#define decode_read_maxsz      (op_decode_hdr_maxsz + 2 + 1)
>>>> #define encode_readdir_maxsz   (op_encode_hdr_maxsz + \
>>>>                                2 + encode_verifier_maxsz + 5 + \
>>>>                               nfs4_label_maxsz)
>>>> #define decode_readdir_maxsz   (op_decode_hdr_maxsz + \
>>>> -                                decode_verifier_maxsz)
>>>> +                                decode_verifier_maxsz + 1)
>>>> #define encode_readlink_maxsz  (op_encode_hdr_maxsz)
>>>> -#define decode_readlink_maxsz  (op_decode_hdr_maxsz + 1)
>>>> +#define decode_readlink_maxsz  (op_decode_hdr_maxsz + 1 + 1)
>>>> #define encode_write_maxsz     (op_encode_hdr_maxsz + \
>>>>                                encode_stateid_maxsz + 4)
>>>> #define decode_write_maxsz     (op_decode_hdr_maxsz + \
>>>> @@ -284,14 +284,14 @@ static int decode_layoutget(struct xdr_stream =
*xdr, struct rpc_rqst *req,
>>>> #define decode_delegreturn_maxsz (op_decode_hdr_maxsz)
>>>> #define encode_getacl_maxsz    (encode_getattr_maxsz)
>>>> #define decode_getacl_maxsz    (op_decode_hdr_maxsz + \
>>>> -                                nfs4_fattr_bitmap_maxsz + 1)
>>>> +                                nfs4_fattr_bitmap_maxsz + 1 + 1)
>>>> #define encode_setacl_maxsz    (op_encode_hdr_maxsz + \
>>>>                                encode_stateid_maxsz + 3)
>>>> #define decode_setacl_maxsz    (decode_setattr_maxsz)
>>>> #define encode_fs_locations_maxsz \
>>>>                               (encode_getattr_maxsz)
>>>> #define decode_fs_locations_maxsz \
>>>> -                               (0)
>>>> +                               (1)
>>>> #define encode_secinfo_maxsz   (op_encode_hdr_maxsz + =
nfs4_name_maxsz)
>>>> #define decode_secinfo_maxsz   (op_decode_hdr_maxsz + 1 + =
((NFS_MAX_SECFLAVORS * (16 + GSS_OID_MAX_LEN)) / 4))
>>>>=20
>>>> @@ -392,12 +392,13 @@ static int decode_layoutget(struct xdr_stream =
*xdr, struct rpc_rqst *req,
>>>>                               1 /* opaque devaddr4 length */ + \
>>>>                                 /* devaddr4 payload is read into =
page */ \
>>>>                               1 /* notification bitmap length */ + =
\
>>>> -                               1 /* notification bitmap, word 0 =
*/)
>>>> +                               1 /* notification bitmap, word 0 */ =
+ \
>>>> +                               1 /* possible XDR padding */)
>>>> #define encode_layoutget_maxsz (op_encode_hdr_maxsz + 10 + \
>>>>                               encode_stateid_maxsz)
>>>> #define decode_layoutget_maxsz (op_decode_hdr_maxsz + 8 + \
>>>>                               decode_stateid_maxsz + \
>>>> -                               XDR_QUADLEN(PNFS_LAYOUT_MAXSIZE))
>>>> +                               XDR_QUADLEN(PNFS_LAYOUT_MAXSIZE) + =
1)
>>>> #define encode_layoutcommit_maxsz (op_encode_hdr_maxsz +          \
>>>>                               2 /* offset */ + \
>>>>                               2 /* length */ + \
>>>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
>>>> index f780605..4ea38b0 100644
>>>> --- a/net/sunrpc/clnt.c
>>>> +++ b/net/sunrpc/clnt.c
>>>> @@ -1177,7 +1177,11 @@ void rpc_prepare_reply_pages(struct rpc_rqst =
*req, struct page **pages,
>>>>                            unsigned int base, unsigned int len,
>>>>                            unsigned int hdrsize)
>>>> {
>>>> -       hdrsize +=3D RPC_REPHDRSIZE + =
req->rq_cred->cr_auth->au_rslack;
>>>> +       /* Subtract one to force an extra word of buffer space for =
the
>>>> +        * payload's XDR pad to fall into the rcv_buf's tail iovec.
>>>> +        */
>>>> +       hdrsize +=3D RPC_REPHDRSIZE + =
req->rq_cred->cr_auth->au_rslack - 1;
>>>> +
>>>>       xdr_inline_pages(&req->rq_rcv_buf, hdrsize << 2, pages, base, =
len);
>>>>       trace_rpc_reply_pages(req);
>>>> }
>>>> diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
>>>> index 7cca515..aa8177d 100644
>>>> --- a/net/sunrpc/xdr.c
>>>> +++ b/net/sunrpc/xdr.c
>>>> @@ -189,6 +189,8 @@ __be32 *xdr_encode_opaque(__be32 *p, const void =
*ptr, unsigned int nbytes)
>>>>=20
>>>>       tail->iov_base =3D buf + offset;
>>>>       tail->iov_len =3D buflen - offset;
>>>> +       if ((xdr->page_len & 3) =3D=3D 0)
>>>> +               tail->iov_len -=3D sizeof(__be32);
>>>>=20
>>>>       xdr->buflen +=3D len;
>>>> }
>>>>=20
>>=20
>> --
>> Chuck Lever

--
Chuck Lever