fs,nfs: lift compat nfs4 mount data handling into the nfs code

There is no reason the generic fs code should bother with NFS specific
binary mount data - lift the conversion into nfs4_parse_monolithic
instead.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/compat.c

@@ -19,73 +19,6 @@
 #include <linux/uaccess.h>
 #include "internal.h"
 
-struct compat_nfs_string {
-	compat_uint_t len;
-	compat_uptr_t data;
-};
-
-static inline void compat_nfs_string(struct nfs_string *dst,
-				     struct compat_nfs_string *src)
-{
-	dst->data = compat_ptr(src->data);
-	dst->len = src->len;
-}
-
-struct compat_nfs4_mount_data_v1 {
-	compat_int_t version;
-	compat_int_t flags;
-	compat_int_t rsize;
-	compat_int_t wsize;
-	compat_int_t timeo;
-	compat_int_t retrans;
-	compat_int_t acregmin;
-	compat_int_t acregmax;
-	compat_int_t acdirmin;
-	compat_int_t acdirmax;
-	struct compat_nfs_string client_addr;
-	struct compat_nfs_string mnt_path;
-	struct compat_nfs_string hostname;
-	compat_uint_t host_addrlen;
-	compat_uptr_t host_addr;
-	compat_int_t proto;
-	compat_int_t auth_flavourlen;
-	compat_uptr_t auth_flavours;
-};
-
-static int do_nfs4_super_data_conv(void *raw_data)
-{
-	int version = *(compat_uint_t *) raw_data;
-
-	if (version == 1) {
-		struct compat_nfs4_mount_data_v1 *raw = raw_data;
-		struct nfs4_mount_data *real = raw_data;
-
-		/* copy the fields backwards */
-		real->auth_flavours = compat_ptr(raw->auth_flavours);
-		real->auth_flavourlen = raw->auth_flavourlen;
-		real->proto = raw->proto;
-		real->host_addr = compat_ptr(raw->host_addr);
-		real->host_addrlen = raw->host_addrlen;
-		compat_nfs_string(&real->hostname, &raw->hostname);
-		compat_nfs_string(&real->mnt_path, &raw->mnt_path);
-		compat_nfs_string(&real->client_addr, &raw->client_addr);
-		real->acdirmax = raw->acdirmax;
-		real->acdirmin = raw->acdirmin;
-		real->acregmax = raw->acregmax;
-		real->acregmin = raw->acregmin;
-		real->retrans = raw->retrans;
-		real->timeo = raw->timeo;
-		real->wsize = raw->wsize;
-		real->rsize = raw->rsize;
-		real->flags = raw->flags;
-		real->version = raw->version;
-	}
-
-	return 0;
-}
-
-#define NFS4_NAME	"nfs4"
-
 COMPAT_SYSCALL_DEFINE5(mount, const char __user *, dev_name,
 		       const char __user *, dir_name,
 		       const char __user *, type, compat_ulong_t, flags,
@@ -111,14 +44,6 @@ COMPAT_SYSCALL_DEFINE5(mount, const char __user *, dev_name,
 	if (IS_ERR(options))
 		goto out2;
 
-	if (kernel_type && options) {
-		if (!strcmp(kernel_type, NFS4_NAME)) {
-			retval = -EINVAL;
-			if (do_nfs4_super_data_conv(options))
-				goto out3;
-		}
-	}
-
 	retval = do_mount(kernel_dev, dir_name, kernel_type, flags, options);
 
  out3:

fs/nfs/fs_context.c

@@ -1037,6 +1037,65 @@ static int nfs23_parse_monolithic(struct fs_context *fc,
 }
 
 #if IS_ENABLED(CONFIG_NFS_V4)
+struct compat_nfs_string {
+	compat_uint_t len;
+	compat_uptr_t data;
+};
+
+static inline void compat_nfs_string(struct nfs_string *dst,
+				     struct compat_nfs_string *src)
+{
+	dst->data = compat_ptr(src->data);
+	dst->len = src->len;
+}
+
+struct compat_nfs4_mount_data_v1 {
+	compat_int_t version;
+	compat_int_t flags;
+	compat_int_t rsize;
+	compat_int_t wsize;
+	compat_int_t timeo;
+	compat_int_t retrans;
+	compat_int_t acregmin;
+	compat_int_t acregmax;
+	compat_int_t acdirmin;
+	compat_int_t acdirmax;
+	struct compat_nfs_string client_addr;
+	struct compat_nfs_string mnt_path;
+	struct compat_nfs_string hostname;
+	compat_uint_t host_addrlen;
+	compat_uptr_t host_addr;
+	compat_int_t proto;
+	compat_int_t auth_flavourlen;
+	compat_uptr_t auth_flavours;
+};
+
+static void nfs4_compat_mount_data_conv(struct nfs4_mount_data *data)
+{
+	struct compat_nfs4_mount_data_v1 *compat =
+			(struct compat_nfs4_mount_data_v1 *)data;
+
+	/* copy the fields backwards */
+	data->auth_flavours = compat_ptr(compat->auth_flavours);
+	data->auth_flavourlen = compat->auth_flavourlen;
+	data->proto = compat->proto;
+	data->host_addr = compat_ptr(compat->host_addr);
+	data->host_addrlen = compat->host_addrlen;
+	compat_nfs_string(&data->hostname, &compat->hostname);
+	compat_nfs_string(&data->mnt_path, &compat->mnt_path);
+	compat_nfs_string(&data->client_addr, &compat->client_addr);
+	data->acdirmax = compat->acdirmax;
+	data->acdirmin = compat->acdirmin;
+	data->acregmax = compat->acregmax;
+	data->acregmin = compat->acregmin;
+	data->retrans = compat->retrans;
+	data->timeo = compat->timeo;
+	data->wsize = compat->wsize;
+	data->rsize = compat->rsize;
+	data->flags = compat->flags;
+	data->version = compat->version;
+}
+
 /*
  * Validate NFSv4 mount options
  */
@@ -1059,6 +1118,9 @@ static int nfs4_parse_monolithic(struct fs_context *fc,
 	if (data->version != 1)
 		return generic_parse_monolithic(fc, data);
 
+	if (in_compat_syscall())
+		nfs4_compat_mount_data_conv(data);
+
 	if (data->host_addrlen > sizeof(ctx->nfs_server.address))
 		goto out_no_address;
 	if (data->host_addrlen == 0)