NFS: Split out the NFS v4 filesystem types

This allows me to move the v4 mounting and unmounting functions out of
the generic client and into a file that is only compiled when CONFIG_NFS_V4
is enabled.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 328 insertions, 0 deletions

diff --git a/fs/nfs/nfs4super.c b/fs/nfs/nfs4super.c
index 70c394e75ca1..2af26913884f 100644
--- a/fs/nfs/nfs4super.c
+++ b/fs/nfs/nfs4super.c
@@ -2,10 +2,331 @@
  * Copyright (c) 2012 Bryan Schumaker <bjschuma@netapp.com>
  */
 #include <linux/init.h>
+#include <linux/module.h>
 #include <linux/nfs_idmap.h>
+#include <linux/nfs4_mount.h>
 #include <linux/nfs_fs.h>
+#include "internal.h"
 #include "nfs4_fs.h"
 
+#define NFSDBG_FACILITY         NFSDBG_VFS
+
+static struct dentry *nfs4_remote_mount(struct file_system_type *fs_type,
+        int flags, const char *dev_name, void *raw_data);
+static struct dentry *nfs4_xdev_mount(struct file_system_type *fs_type,
+        int flags, const char *dev_name, void *raw_data);
+static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
+        int flags, const char *dev_name, void *raw_data);
+static struct dentry *nfs4_remote_referral_mount(struct file_system_type *fs_type,
+        int flags, const char *dev_name, void *raw_data);
+
+static struct file_system_type nfs4_fs_type = {
+        .owner          = THIS_MODULE,
+        .name           = "nfs4",
+        .mount          = nfs_fs_mount,
+        .kill_sb        = nfs_kill_super,
+        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+};
+
+static struct file_system_type nfs4_remote_fs_type = {
+        .owner          = THIS_MODULE,
+        .name           = "nfs4",
+        .mount          = nfs4_remote_mount,
+        .kill_sb        = nfs_kill_super,
+        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+};
+
+struct file_system_type nfs4_xdev_fs_type = {
+        .owner          = THIS_MODULE,
+        .name           = "nfs4",
+        .mount          = nfs4_xdev_mount,
+        .kill_sb        = nfs_kill_super,
+        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+};
+
+static struct file_system_type nfs4_remote_referral_fs_type = {
+        .owner          = THIS_MODULE,
+        .name           = "nfs4",
+        .mount          = nfs4_remote_referral_mount,
+        .kill_sb        = nfs_kill_super,
+        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+};
+
+struct file_system_type nfs4_referral_fs_type = {
+        .owner          = THIS_MODULE,
+        .name           = "nfs4",
+        .mount          = nfs4_referral_mount,
+        .kill_sb        = nfs_kill_super,
+        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+};
+
+static const struct super_operations nfs4_sops = {
+        .alloc_inode    = nfs_alloc_inode,
+        .destroy_inode  = nfs_destroy_inode,
+        .write_inode    = nfs4_write_inode,
+        .put_super      = nfs_put_super,
+        .statfs         = nfs_statfs,
+        .evict_inode    = nfs4_evict_inode,
+        .umount_begin   = nfs_umount_begin,
+        .show_options   = nfs_show_options,
+        .show_devname   = nfs_show_devname,
+        .show_path      = nfs_show_path,
+        .show_stats     = nfs_show_stats,
+        .remount_fs     = nfs_remount,
+};
+
+/*
+ * Set up an NFS4 superblock
+ */
+static void nfs4_fill_super(struct super_block *sb,
+                            struct nfs_mount_info *mount_info)
+{
+        sb->s_time_gran = 1;
+        sb->s_op = &nfs4_sops;
+        /*
+         * The VFS shouldn't apply the umask to mode bits. We will do
+         * so ourselves when necessary.
+         */
+        sb->s_flags  |= MS_POSIXACL;
+        sb->s_xattr = nfs4_xattr_handlers;
+        nfs_initialise_sb(sb);
+}
+
+/*
+ * Get the superblock for the NFS4 root partition
+ */
+static struct dentry *
+nfs4_remote_mount(struct file_system_type *fs_type, int flags,
+                  const char *dev_name, void *info)
+{
+        struct nfs_mount_info *mount_info = info;
+        struct nfs_server *server;
+        struct dentry *mntroot = ERR_PTR(-ENOMEM);
+
+        mount_info->fill_super = nfs4_fill_super;
+        mount_info->set_security = nfs_set_sb_security;
+
+        /* Get a volume representation */
+        server = nfs4_create_server(mount_info->parsed, mount_info->mntfh);
+        if (IS_ERR(server)) {
+                mntroot = ERR_CAST(server);
+                goto out;
+        }
+
+        mntroot = nfs_fs_mount_common(fs_type, server, flags, dev_name, mount_info);
+
+out:
+        return mntroot;
+}
+
+static struct vfsmount *nfs_do_root_mount(struct file_system_type *fs_type,
+                int flags, void *data, const char *hostname)
+{
+        struct vfsmount *root_mnt;
+        char *root_devname;
+        size_t len;
+
+        len = strlen(hostname) + 5;
+        root_devname = kmalloc(len, GFP_KERNEL);
+        if (root_devname == NULL)
+                return ERR_PTR(-ENOMEM);
+        /* Does hostname needs to be enclosed in brackets? */
+        if (strchr(hostname, ':'))
+                snprintf(root_devname, len, "[%s]:/", hostname);
+        else
+                snprintf(root_devname, len, "%s:/", hostname);
+        root_mnt = vfs_kern_mount(fs_type, flags, root_devname, data);
+        kfree(root_devname);
+        return root_mnt;
+}
+
+struct nfs_referral_count {
+        struct list_head list;
+        const struct task_struct *task;
+        unsigned int referral_count;
+};
+
+static LIST_HEAD(nfs_referral_count_list);
+static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
+
+static struct nfs_referral_count *nfs_find_referral_count(void)
+{
+        struct nfs_referral_count *p;
+
+        list_for_each_entry(p, &nfs_referral_count_list, list) {
+                if (p->task == current)
+                        return p;
+        }
+        return NULL;
+}
+
+#define NFS_MAX_NESTED_REFERRALS 2
+
+static int nfs_referral_loop_protect(void)
+{
+        struct nfs_referral_count *p, *new;
+        int ret = -ENOMEM;
+
+        new = kmalloc(sizeof(*new), GFP_KERNEL);
+        if (!new)
+                goto out;
+        new->task = current;
+        new->referral_count = 1;
+
+        ret = 0;
+        spin_lock(&nfs_referral_count_list_lock);
+        p = nfs_find_referral_count();
+        if (p != NULL) {
+                if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
+                        ret = -ELOOP;
+                else
+                        p->referral_count++;
+        } else {
+                list_add(&new->list, &nfs_referral_count_list);
+                new = NULL;
+        }
+        spin_unlock(&nfs_referral_count_list_lock);
+        kfree(new);
+out:
+        return ret;
+}
+
+static void nfs_referral_loop_unprotect(void)
+{
+        struct nfs_referral_count *p;
+
+        spin_lock(&nfs_referral_count_list_lock);
+        p = nfs_find_referral_count();
+        p->referral_count--;
+        if (p->referral_count == 0)
+                list_del(&p->list);
+        else
+                p = NULL;
+        spin_unlock(&nfs_referral_count_list_lock);
+        kfree(p);
+}
+
+static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt,
+                const char *export_path)
+{
+        struct dentry *dentry;
+        int err;
+
+        if (IS_ERR(root_mnt))
+                return ERR_CAST(root_mnt);
+
+        err = nfs_referral_loop_protect();
+        if (err) {
+                mntput(root_mnt);
+                return ERR_PTR(err);
+        }
+
+        dentry = mount_subtree(root_mnt, export_path);
+        nfs_referral_loop_unprotect();
+
+        return dentry;
+}
+
+struct dentry *nfs4_try_mount(int flags, const char *dev_name,
+                         struct nfs_mount_info *mount_info)
+{
+        char *export_path;
+        struct vfsmount *root_mnt;
+        struct dentry *res;
+        struct nfs_parsed_mount_data *data = mount_info->parsed;
+
+        dfprintk(MOUNT, "--> nfs4_try_mount()\n");
+
+        mount_info->fill_super = nfs4_fill_super;
+
+        export_path = data->nfs_server.export_path;
+        data->nfs_server.export_path = "/";
+        root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, mount_info,
+                        data->nfs_server.hostname);
+        data->nfs_server.export_path = export_path;
+
+        res = nfs_follow_remote_path(root_mnt, export_path);
+
+        dfprintk(MOUNT, "<-- nfs4_try_mount() = %ld%s\n",
+                        IS_ERR(res) ? PTR_ERR(res) : 0,
+                        IS_ERR(res) ? " [error]" : "");
+        return res;
+}
+
+/*
+ * Clone an NFS4 server record on xdev traversal (FSID-change)
+ */
+static struct dentry *
+nfs4_xdev_mount(struct file_system_type *fs_type, int flags,
+                 const char *dev_name, void *raw_data)
+{
+        struct nfs_mount_info mount_info = {
+                .fill_super = nfs_clone_super,
+                .set_security = nfs_clone_sb_security,
+                .cloned = raw_data,
+        };
+        return nfs_xdev_mount_common(&nfs4_fs_type, flags, dev_name, &mount_info);
+}
+
+static struct dentry *
+nfs4_remote_referral_mount(struct file_system_type *fs_type, int flags,
+                           const char *dev_name, void *raw_data)
+{
+        struct nfs_mount_info mount_info = {
+                .fill_super = nfs4_fill_super,
+                .set_security = nfs_clone_sb_security,
+                .cloned = raw_data,
+        };
+        struct nfs_server *server;
+        struct dentry *mntroot = ERR_PTR(-ENOMEM);
+
+        dprintk("--> nfs4_referral_get_sb()\n");
+
+        mount_info.mntfh = nfs_alloc_fhandle();
+        if (mount_info.cloned == NULL || mount_info.mntfh == NULL)
+                goto out;
+
+        /* create a new volume representation */
+        server = nfs4_create_referral_server(mount_info.cloned, mount_info.mntfh);
+        if (IS_ERR(server)) {
+                mntroot = ERR_CAST(server);
+                goto out;
+        }
+
+        mntroot = nfs_fs_mount_common(&nfs4_fs_type, server, flags, dev_name, &mount_info);
+out:
+        nfs_free_fhandle(mount_info.mntfh);
+        return mntroot;
+}
+
+/*
+ * Create an NFS4 server record on referral traversal
+ */
+static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
+                int flags, const char *dev_name, void *raw_data)
+{
+        struct nfs_clone_mount *data = raw_data;
+        char *export_path;
+        struct vfsmount *root_mnt;
+        struct dentry *res;
+
+        dprintk("--> nfs4_referral_mount()\n");
+
+        export_path = data->mnt_path;
+        data->mnt_path = "/";
+
+        root_mnt = nfs_do_root_mount(&nfs4_remote_referral_fs_type,
+                        flags, data, data->hostname);
+        data->mnt_path = export_path;
+
+        res = nfs_follow_remote_path(root_mnt, export_path);
+        dprintk("<-- nfs4_referral_mount() = %ld%s\n",
+                        IS_ERR(res) ? PTR_ERR(res) : 0,
+                        IS_ERR(res) ? " [error]" : "");
+        return res;
+}
+
+
 int __init init_nfs_v4(void)
 {
         int err;
@@ -18,7 +339,13 @@ int __init init_nfs_v4(void)
         if (err)
                 goto out1;
 
+        err = register_filesystem(&nfs4_fs_type);
+        if (err < 0)
+                goto out2;
+
         return 0;
+out2:
+        nfs4_unregister_sysctl();
 out1:
         nfs_idmap_quit();
 out:
@@ -27,6 +354,7 @@ out:
 
 void __exit exit_nfs_v4(void)
 {
+        unregister_filesystem(&nfs4_fs_type);
         nfs4_unregister_sysctl();
         nfs_idmap_quit();
 }