On Fri, 2009-05-01 at 12:36 -0400, Chuck Lever wrote:
> Introduce data structures and xdr_stream-based decoding functions for
> unmarshalling mountd status codes properly.
>
> Mountd version 3 uses specific standard error return codes that are
> not errno values and not NFS3ERR_ values. These have a well-defined
> standard mapping to local errno values. Introduce data structures
> and a decoder function that map these status codes to local errno
> values properly. This is new functionality (but not used yet).
>
> Version 1 mountd status values are defined by RFC 1094 as UNIX error
> values (errno values). Errno values on heterogeneous systems do not
> necessarily match each other. To avoid exposing possibly incorrect
> errno values to upper layers, the current XDR decoder converts all
> non-zero MNT version 1 status codes to -EACCES.
>
> The OpenGroup XNFS standard provides a mapping similar to but smaller
> than the version 3 error codes. Implement a decoder that uses the XNFS
> error codes, replacing the current decoder.
>
> For both mountd protocol versions, map unrecognized errors to -EACCES.
>
> Finally we introduce a replacement data structure for mnt_fhstatus
> at this time, which is used by the new XDR decoders. In addition to
> documenting that the status value returned by the XDR decoders is
> always an errno, this new structure will be expanded in subsequent
> patches.
>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
>
> fs/nfs/mount_clnt.c | 134 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 134 insertions(+), 0 deletions(-)
>
> diff --git a/fs/nfs/mount_clnt.c b/fs/nfs/mount_clnt.c
> index 7b81914..cdda067 100644
> --- a/fs/nfs/mount_clnt.c
> +++ b/fs/nfs/mount_clnt.c
> @@ -29,6 +29,8 @@
> * XDR data type sizes
> */
> #define encode_dirpath_sz XDR_QUADLEN(sizeof(u32) + MNTPATHLEN)
> +#define MNT_status_sz XDR_QUADLEN(sizeof(u32))
> +#define MNT_fhs_status_sz XDR_QUADLEN(sizeof(u32))
XDR_QUADLEN() applies to strings only. Please just use naked numbers
here. I've already fixed up the previous patch that did this.
>
> /*
> * XDR argument and result sizes
> @@ -61,6 +63,83 @@ enum {
>
> static struct rpc_program mnt_program;
>
> +/*
> + * Defined by OpenGroup XNFS Version 3W, chapter 8
> + */
> +enum mountstat {
> + MNT_OK = 0,
> + MNT_EPERM = 1,
> + MNT_ENOENT = 2,
> + MNT_EACCES = 13,
> + MNT_EINVAL = 22,
> +};
> +
> +#define MNT_MAPERRNO(name) \
> + { \
> + .status = MNT_E##name, \
> + .errno = -E##name, \
> + }
It would be nice to avoid this kind of macro. Please inline instead.
> +
> +static struct {
> + u32 status;
> + int errno;
> +} mnt_errtbl[] = {
> + {
> + .status = MNT_OK,
> + .errno = 0,
> + },
> + MNT_MAPERRNO(PERM),
> + MNT_MAPERRNO(NOENT),
> + MNT_MAPERRNO(ACCES),
> + MNT_MAPERRNO(INVAL),
> +};
> +
> +/*
> + * Defined by RFC 1813, section 5.1.5
> + */
> +enum mountstat3 {
> + MNT3_OK = 0, /* no error */
> + MNT3ERR_PERM = 1, /* Not owner */
> + MNT3ERR_NOENT = 2, /* No such file or directory */
> + MNT3ERR_IO = 5, /* I/O error */
> + MNT3ERR_ACCES = 13, /* Permission denied */
> + MNT3ERR_NOTDIR = 20, /* Not a directory */
> + MNT3ERR_INVAL = 22, /* Invalid argument */
> + MNT3ERR_NAMETOOLONG = 63, /* Filename too long */
> + MNT3ERR_NOTSUPP = 10004, /* Operation not supported */
> + MNT3ERR_SERVERFAULT = 10006, /* A failure on the server */
> +};
> +
> +#define MNT3_MAPERRNO(name) \
> + { \
> + .status = MNT3ERR_##name, \
> + .errno = -E##name, \
> + }
See above
> +static struct {
> + u32 status;
> + int errno;
> +} mnt3_errtbl[] = {
> + {
> + .status = MNT3_OK,
> + .errno = 0,
> + },
> + MNT3_MAPERRNO(PERM),
> + MNT3_MAPERRNO(NOENT),
> + MNT3_MAPERRNO(IO),
> + MNT3_MAPERRNO(ACCES),
> + MNT3_MAPERRNO(NOTDIR),
> + MNT3_MAPERRNO(INVAL),
> + MNT3_MAPERRNO(NAMETOOLONG),
> + MNT3_MAPERRNO(NOTSUPP),
> + MNT3_MAPERRNO(SERVERFAULT),
> +};
> +
> +struct mountres {
> + int errno;
> + struct nfs_fh *fh;
> +};
> +
> struct mnt_fhstatus {
> u32 status;
> struct nfs_fh *fh;
> @@ -179,6 +258,61 @@ static int xdr_decode_fhstatus(struct rpc_rqst *req, __be32 *p,
> return 0;
> }
>
> +/*
> + * RFC 1094: "A non-zero status indicates some sort of error. In this
> + * case, the status is a UNIX error number." This can be problematic
> + * if the server and client use different errno values for the same
> + * error.
> + *
> + * However, the OpenGroup XNFS spec provides a simple mapping that is
> + * independent of local errno values on the server and the client.
> + */
> +static int decode_status(struct xdr_stream *xdr, struct mountres *res)
> +{
> + unsigned int i;
> + u32 status;
> + __be32 *p;
> +
> + p = xdr_inline_decode(xdr, sizeof(status));
> + if (unlikely(p == NULL))
> + return -EIO;
> + status = ntohl(*p);
> +
> + for (i = 0; i <= ARRAY_SIZE(mnt_errtbl); i++) {
> + if (mnt_errtbl[i].status == status) {
> + res->errno = mnt_errtbl[i].errno;
> + return 0;
> + }
> + }
> +
> + dprintk("NFS: unrecognized MNT status code: %u\n", status);
> + res->errno = -EACCES;
> + return 0;
> +}
> +
> +static int decode_fhs_status(struct xdr_stream *xdr, struct mountres *res)
> +{
> + unsigned int i;
> + u32 status;
> + __be32 *p;
> +
> + p = xdr_inline_decode(xdr, sizeof(status));
> + if (unlikely(p == NULL))
> + return -EIO;
> + status = ntohl(*p);
> +
> + for (i = 0; i <= ARRAY_SIZE(mnt3_errtbl); i++) {
> + if (mnt3_errtbl[i].status == status) {
> + res->errno = mnt3_errtbl[i].errno;
> + return 0;
> + }
> + }
> +
> + dprintk("NFS: unrecognized MNT3 status code: %u\n", status);
> + res->errno = -EACCES;
> + return 0;
> +}
> +
> static int xdr_decode_fhstatus3(struct rpc_rqst *req, __be32 *p,
> struct mnt_fhstatus *res)
> {
>
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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