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    Subject[PATCH 6/13: eCryptfs] Superblock operations
    This is the 6th patch in a series of 13 constituting the kernel
    components of the eCryptfs cryptographic filesystem.

    eCryptfs superblock operations and inode allocation, deallocation, and
    initialization functions.

    Signed-off-by: Phillip Hellewell <phillip@hellewell.homeip.net>
    Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>

    ---

    super.c | 212 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    1 files changed, 212 insertions(+)

    Index: linux-2.6.17-rc3-mm1-ecryptfs/fs/ecryptfs/super.c
    ===================================================================
    --- /dev/null 1970-01-01 00:00:00.000000000 +0000
    +++ linux-2.6.17-rc3-mm1-ecryptfs/fs/ecryptfs/super.c 2006-05-12 20:00:30.000000000 -0600
    @@ -0,0 +1,212 @@
    +/**
    + * eCryptfs: Linux filesystem encryption layer
    + *
    + * Copyright (C) 1997-2003 Erez Zadok
    + * Copyright (C) 2001-2003 Stony Brook University
    + * Copyright (C) 2004-2006 International Business Machines Corp.
    + * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
    + * Michael C. Thompson <mcthomps@us.ibm.com>
    + *
    + * This program is free software; you can redistribute it and/or
    + * modify it under the terms of the GNU General Public License as
    + * published by the Free Software Foundation; either version 2 of the
    + * License, or (at your option) any later version.
    + *
    + * This program is distributed in the hope that it will be useful, but
    + * WITHOUT ANY WARRANTY; without even the implied warranty of
    + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    + * General Public License for more details.
    + *
    + * You should have received a copy of the GNU General Public License
    + * along with this program; if not, write to the Free Software
    + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
    + * 02111-1307, USA.
    + */
    +
    +#include <linux/fs.h>
    +#include <linux/mount.h>
    +#include <linux/key.h>
    +#include <linux/seq_file.h>
    +#include "ecryptfs_kernel.h"
    +
    +struct kmem_cache *ecryptfs_inode_info_cache;
    +
    +/**
    + * ecryptfs_alloc_inode - allocate an ecryptfs inode
    + * @sb: Pointer to the ecryptfs super block
    + *
    + * Called to bring an inode into existence.
    + *
    + * Note that setting the self referencing pointer doesn't work here:
    + * i.e. ECRYPTFS_INODE_TO_PRIVATE_SM(inode) = ei;
    + *
    + * Only handle allocation, setting up structures should be done in
    + * ecryptfs_read_inode. This is because the kernel, between now and
    + * then, will 0 out the private data pointer.
    + *
    + * Returns a pointer to a newly allocated inode, NULL otherwise
    + */
    +static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
    +{
    + struct ecryptfs_inode_info *ecryptfs_inode;
    + struct inode *inode = NULL;
    +
    + ecryptfs_inode = kmem_cache_alloc(ecryptfs_inode_info_cache,
    + SLAB_KERNEL);
    + if (unlikely(!ecryptfs_inode))
    + goto out;
    + ecryptfs_init_crypt_stat(&ecryptfs_inode->crypt_stat);
    + inode = &ecryptfs_inode->vfs_inode;
    +out:
    + return inode;
    +}
    +
    +/**
    + * ecryptfs_destroy_inode
    + * @inode: The ecryptfs inode
    + *
    + * This is used during the final destruction of the inode.
    + * All allocation of memory related to the inode, including allocated
    + * memory in the crypt_stat struct, will be released here.
    + * There should be no chance that this deallocation will be missed.
    + */
    +static void ecryptfs_destroy_inode(struct inode *inode)
    +{
    + struct ecryptfs_inode_info *inode_info;
    +
    + inode_info = ecryptfs_inode_to_private(inode);
    + ecryptfs_destruct_crypt_stat(&inode_info->crypt_stat);
    + kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
    +}
    +
    +/**
    + * ecryptfs_read_inode
    + * @inode: The ecryptfs inode
    + *
    + * Set up the ecryptfs inode.
    + */
    +static void ecryptfs_read_inode(struct inode *inode)
    +{
    + /* This is where we setup the self-reference in the vfs_inode's
    + * u.generic_ip. That way we don't have to walk the list again. */
    + ecryptfs_set_inode_private(inode,
    + list_entry(inode, struct ecryptfs_inode_info,
    + vfs_inode));
    + ecryptfs_set_inode_lower(inode, NULL);
    + inode->i_version++;
    + inode->i_op = &ecryptfs_main_iops;
    + inode->i_fop = &ecryptfs_main_fops;
    + inode->i_mapping->a_ops = &ecryptfs_aops;
    +}
    +
    +/**
    + * ecryptfs_put_super
    + * @sb: Pointer to the ecryptfs super block
    + *
    + * Final actions when unmounting a file system.
    + * This will handle deallocation and release of our private data.
    + */
    +static void ecryptfs_put_super(struct super_block *sb)
    +{
    + struct ecryptfs_sb_info *sb_info = ecryptfs_superblock_to_private(sb);
    +
    + mntput(sb_info->lower_mnt);
    + key_put(sb_info->mount_crypt_stat.global_auth_tok_key);
    + kmem_cache_free(ecryptfs_sb_info_cache, sb_info);
    + ecryptfs_set_superblock_private(sb, NULL);
    +}
    +
    +/**
    + * ecryptfs_statfs
    + * @sb: The ecryptfs super block
    + * @buf: The struct kstatfs to fill in with stats
    + *
    + * Get the filesystem statistics. Currently, we let this pass right through
    + * to the lower filesystem and take no action ourselves.
    + */
    +static inline int ecryptfs_statfs(struct super_block *sb, struct kstatfs *buf)
    +{
    + return vfs_statfs(ecryptfs_superblock_to_lower(sb), buf);
    +}
    +
    +/**
    + * ecryptfs_clear_inode
    + * @inode - The ecryptfs inode
    + *
    + * Called by iput() when the inode reference count reached zero
    + * and the inode is not hashed anywhere. Used to clear anything
    + * that needs to be, before the inode is completely destroyed and put
    + * on the inode free list. We use this to drop out reference to the
    + * lower inode.
    + */
    +static inline void ecryptfs_clear_inode(struct inode *inode)
    +{
    + iput(ecryptfs_inode_to_lower(inode));
    +}
    +
    +/**
    + * ecryptfs_umount_begin
    + *
    + * Called in do_umount() if the MNT_FORCE flag was used and this
    + * function is defined. See comment in linux/fs/super.c:do_umount().
    + * Used only in nfs, to kill any pending RPC tasks, so that subsequent
    + * code can actually succeed and won't leave tasks that need handling.
    + */
    +static void ecryptfs_umount_begin(struct vfsmount *vfsmnt, int flags)
    +{
    + struct vfsmount *lower_mnt;
    + struct super_block *lower_sb;
    +
    + lower_mnt = ecryptfs_superblock_to_private(vfsmnt->mnt_sb)->lower_mnt;
    + lower_sb = lower_mnt->mnt_sb;
    + if (lower_sb->s_op->umount_begin)
    + lower_sb->s_op->umount_begin(lower_mnt, flags);
    +}
    +
    +/**
    + * ecryptfs_show_options
    + *
    + * Prints the directory we are currently mounted over.
    + * Returns zero on success; non-zero otherwise
    + */
    +static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt)
    +{
    + struct super_block *sb = mnt->mnt_sb;
    + struct dentry *lower_root_dentry;
    + struct ecryptfs_sb_info *sb_info;
    + struct vfsmount *lower_mount;
    + int rc = 0;
    + char *tmp_page = NULL;
    + char *path;
    +
    + tmp_page = (char *)__get_free_page(GFP_KERNEL);
    + if (!tmp_page) {
    + rc = -ENOMEM;
    + goto out;
    + }
    + lower_root_dentry = ecryptfs_dentry_to_lower(sb->s_root);
    + sb_info = ecryptfs_superblock_to_private(sb);
    + lower_mount = sb_info->lower_mnt;
    + path = d_path(lower_root_dentry, lower_mount, tmp_page, PAGE_SIZE);
    + if (IS_ERR(path)) {
    + rc = PTR_ERR(path);
    + goto out;
    + }
    + seq_printf(m, ",dir=%s", path);
    + free_page((unsigned long)tmp_page);
    +out:
    + return rc;
    +}
    +
    +struct super_operations ecryptfs_sops = {
    + .alloc_inode = ecryptfs_alloc_inode,
    + .destroy_inode = ecryptfs_destroy_inode,
    + .read_inode = ecryptfs_read_inode,
    + .drop_inode = generic_delete_inode,
    + .put_super = ecryptfs_put_super,
    + .statfs = ecryptfs_statfs,
    + .remount_fs = NULL,
    + .clear_inode = ecryptfs_clear_inode,
    + .umount_begin = ecryptfs_umount_begin,
    + .show_options = ecryptfs_show_options
    +};
    -
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