NFS: Add final pieces to support in-kernel mount option parsing

Hook in final components required for supporting in-kernel mount option
parsing for NFSv2 and NFSv3 mounts.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 95 insertions, 10 deletions

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 48db52a7067a..757aa3b7e64b 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1051,10 +1051,28 @@ out_err:
 /*
  * Validate the NFS2/NFS3 mount data
  * - fills in the mount root filehandle
+ *
+ * For option strings, user space handles the following behaviors:
+ *
+ * + DNS: mapping server host name to IP address ("addr=" option)
+ *
+ * + failure mode: how to behave if a mount request can't be handled
+ *   immediately ("fg/bg" option)
+ *
+ * + retry: how often to retry a mount request ("retry=" option)
+ *
+ * + breaking back: trying proto=udp after proto=tcp, v2 after v3,
+ *   mountproto=tcp after mountproto=udp, and so on
+ *
+ * XXX: as far as I can tell, changing the NFS program number is not
+ *      supported in the NFS client.
  */
-static int nfs_validate_mount_data(struct nfs_mount_data *data,
-                                   struct nfs_fh *mntfh)
+static int nfs_validate_mount_data(struct nfs_mount_data **options,
+                                   struct nfs_fh *mntfh,
+                                   const char *dev_name)
 {
+        struct nfs_mount_data *data = *options;
+
         if (data == NULL)
                 goto out_no_data;
 
@@ -1087,8 +1105,78 @@ static int nfs_validate_mount_data(struct nfs_mount_data *data,
                         memset(mntfh->data + mntfh->size, 0,
                                sizeof(mntfh->data) - mntfh->size);
                 break;
-        default:
-                goto out_bad_version;
+        default: {
+                unsigned int len;
+                char *c;
+                int status;
+                struct nfs_parsed_mount_data args = {
+                        .flags          = (NFS_MOUNT_VER3 | NFS_MOUNT_TCP),
+                        .rsize          = NFS_MAX_FILE_IO_SIZE,
+                        .wsize          = NFS_MAX_FILE_IO_SIZE,
+                        .timeo          = 600,
+                        .retrans        = 2,
+                        .acregmin       = 3,
+                        .acregmax       = 60,
+                        .acdirmin       = 30,
+                        .acdirmax       = 60,
+                        .mount_server.protocol = IPPROTO_UDP,
+                        .mount_server.program = NFS_MNT_PROGRAM,
+                        .nfs_server.protocol = IPPROTO_TCP,
+                        .nfs_server.program = NFS_PROGRAM,
+                };
+
+                if (nfs_parse_mount_options((char *) *options, &args) == 0)
+                        return -EINVAL;
+
+                data = kzalloc(sizeof(*data), GFP_KERNEL);
+                if (data == NULL)
+                        return -ENOMEM;
+
+                /*
+                 * NB: after this point, caller will free "data"
+                 * if we return an error
+                 */
+                *options = data;
+
+                c = strchr(dev_name, ':');
+                if (c == NULL)
+                        return -EINVAL;
+                len = c - dev_name - 1;
+                if (len > sizeof(data->hostname))
+                        return -EINVAL;
+                strncpy(data->hostname, dev_name, len);
+                args.nfs_server.hostname = data->hostname;
+
+                c++;
+                if (strlen(c) > NFS_MAXPATHLEN)
+                        return -EINVAL;
+                args.nfs_server.export_path = c;
+
+                status = nfs_try_mount(&args, mntfh);
+                if (status)
+                        return -EINVAL;
+
+                /*
+                 * Translate to nfs_mount_data, which nfs_fill_super
+                 * can deal with.
+                 */
+                data->version           = 6;
+                data->flags             = args.flags;
+                data->rsize             = args.rsize;
+                data->wsize             = args.wsize;
+                data->timeo             = args.timeo;
+                data->retrans           = args.retrans;
+                data->acregmin          = args.acregmin;
+                data->acregmax          = args.acregmax;
+                data->acdirmin          = args.acdirmin;
+                data->acdirmax          = args.acdirmax;
+                data->addr              = args.nfs_server.address;
+                data->namlen            = args.namlen;
+                data->bsize             = args.bsize;
+                data->pseudoflavor      = args.auth_flavors[0];
+
+                break;
+                }
         }
 
         if (!(data->flags & NFS_MOUNT_SECFLAVOUR))
@@ -1117,11 +1205,6 @@ out_no_sec:
         dfprintk(MOUNT, "NFS: nfs_mount_data version supports only AUTH_SYS\n");
         return -EINVAL;
 
-out_bad_version:
-        dfprintk(MOUNT, "NFS: bad nfs_mount_data version %d\n",
-                 data->version);
-        return -EINVAL;
-
 #ifndef CONFIG_NFS_V3
 out_v3_not_compiled:
         dfprintk(MOUNT, "NFS: NFSv3 is not compiled into kernel\n");
@@ -1242,7 +1325,7 @@ static int nfs_get_sb(struct file_system_type *fs_type,
         int error;
 
         /* Validate the mount data */
-        error = nfs_validate_mount_data(data, &mntfh);
+        error = nfs_validate_mount_data(&data, &mntfh, dev_name);
         if (error < 0)
                 goto out;
 
@@ -1283,6 +1366,8 @@ static int nfs_get_sb(struct file_system_type *fs_type,
         error = 0;
 
 out:
+        if (data != raw_data)
+                kfree(data);
         return error;
 
 out_err_nosb: