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    Subject[PATCH 6/12: eCryptfs] Superblock operations
    eCryptfs superblock operations and inode
    allocation/deallocation/initialization functions.

    Signed off by: Phillip Hellewell <phillip@hellewell.homeip.net>
    Signed off by: Michael Halcrow <mhalcrow@us.ibm.com>
    Signed off by: Michael Thompson <mmcthomps@us.ibm.com>
    Signed off by: Kent Yoder <yoder1@us.ibm.com>

    super.c | 246 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    1 files changed, 246 insertions(+)
    --- linux-2.6.14-rc5-mm1/fs/ecryptfs/super.c 1969-12-31 18:00:00.000000000 -0600
    +++ linux-2.6.14-rc5-mm1-ecryptfs/fs/ecryptfs/super.c 2005-11-01 14:40:17.000000000 -0600
    @@ -0,0 +1,246 @@
    +/**
    + * eCryptfs: Linux filesystem encryption layer
    + *
    + * Copyright (c) 1997-2003 Erez Zadok
    + * Copyright (c) 2001-2003 Stony Brook University
    + * Copyright (c) 2005 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.
    + */
    +
    +#ifdef HAVE_CONFIG_H
    +# include <config.h>
    +#endif /* HAVE_CONFIG_H */
    +#include <linux/fs.h>
    +#include <linux/mount.h>
    +#include <linux/key.h>
    +#include "ecryptfs_kernel.h"
    +
    +kmem_cache_t *ecryptfs_inode_info_cache;
    +
    +/**
    + * Called to bring an inode into existence.
    + *
    + * Note that setting the self referencing pointer doesn't work here:
    + * i.e. 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.
    + *
    + * @param sb Pointer to the super block of the filesystem
    + * @return Pointer to a newly allocated inode, NULL otherwise
    + */
    +static struct inode *ecryptfs_alloc_inode(struct super_block *sb) {
    + struct ecryptfs_inode_info *ecryptfs_inode = NULL;
    + struct inode *inode = NULL;
    + ecryptfs_printk(1, KERN_NOTICE, "Enter; sb = [%p]\n", sb);
    + ecryptfs_inode = ecryptfs_kmem_cache_alloc(ecryptfs_inode_info_cache,
    + SLAB_KERNEL);
    + if (unlikely(!ecryptfs_inode)) {
    + ecryptfs_printk(1, KERN_WARNING,
    + "Failed to allocate new inode\n");
    + goto out;
    + }
    + ecryptfs_init_crypt_stats(&(ecryptfs_inode->crypt_stats));
    + inode = &(ecryptfs_inode->vfs_inode);
    + out:
    + ecryptfs_printk(1, KERN_NOTICE, "Exit; inode = [%p]\n", inode);
    + return 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_stats 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_crypt_stats *crypt_stats;
    + ecryptfs_printk(1, KERN_NOTICE, "Enter; inode = [%p]\n", inode);
    + crypt_stats = &(INODE_TO_PRIVATE(inode))->crypt_stats;
    + ecryptfs_destruct_crypt_stats(crypt_stats);
    + ecryptfs_kmem_cache_free(ecryptfs_inode_info_cache,
    + INODE_TO_PRIVATE(inode));
    + ecryptfs_printk(1, KERN_NOTICE, "Exit\n");
    +}
    +
    +/**
    + * Return a pointer to our ecryptfs_inode_info struct.
    + * This is specified by the kernel documentation for the alloc_inode &
    + * destroy_inode change. We use this function to get a handle to our
    + * ecryptfs specific data.
    + *
    + * @param inode The inode component of the ecryptfs_inode_info we want to find
    + * @return Handle to our ecryptfs_inode_info
    + */
    +static inline struct ecryptfs_inode_info *ECRYPTFS_I(struct inode *inode)
    +{
    + return list_entry(inode, struct ecryptfs_inode_info, vfs_inode);
    +}
    +
    +/**
    + * Set up the ecryptfs inode.
    + */
    +static void ecryptfs_read_inode(struct inode *inode)
    +{
    + ecryptfs_printk(1, KERN_NOTICE, "Enter; inode = [%p]\n", 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. */
    + INODE_TO_PRIVATE_SM(inode) = ECRYPTFS_I(inode);
    + INODE_TO_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_printk(1, KERN_NOTICE, "Exit\n");
    +}
    +
    +
    +/**
    + * This is called through iput_final().
    + * This is function will replace generic_drop_inode. The end result of which
    + * is we are skipping the check in inode->i_nlink, which we do not use.
    + */
    +static void ecryptfs_drop_inode(struct inode *inode) {
    + generic_delete_inode(inode);
    +}
    +
    +/**
    + * 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 = SUPERBLOCK_TO_PRIVATE(sb);
    + ecryptfs_printk(1, KERN_NOTICE, "Enter\n");
    + mntput(sb_info->lower_mnt);
    + key_put(sb_info->mount_crypt_stats.global_auth_tok_key);
    + ecryptfs_kmem_cache_free(ecryptfs_sb_info_cache, sb_info);
    + SUPERBLOCK_TO_PRIVATE_SM(sb) = NULL;
    + ecryptfs_printk(1, KERN_NOTICE, "Exit\n");
    +}
    +
    +/**
    + * Get the filesystem statistics. Currently, we let this pass right through
    + * to the lower filesystem and take no action ourselves
    + *
    + * TODO: Any stats need to be transposed?
    + */
    +static int ecryptfs_statfs(struct super_block *sb, struct kstatfs *buf)
    +{
    + int err = 0;
    + ecryptfs_printk(1, KERN_NOTICE, "Enter\n");
    + err = vfs_statfs(SUPERBLOCK_TO_LOWER(sb), buf);
    + ecryptfs_printk(1, KERN_NOTICE, "Exit; err = [%d]\n",err);
    + return err;
    +}
    +
    +/**
    + * TODO: Not implemented.
    + * Called to ask filesystem to change mount options.
    + */
    +static int ecryptfs_remount_fs(struct super_block *sb, int *flags, char *data)
    +{
    + ecryptfs_printk(1, KERN_NOTICE, "Enter\n");
    + ecryptfs_printk(1, KERN_NOTICE, "Exit\n");
    + return -ENOSYS;
    +}
    +
    +/**
    + * 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.
    + *
    + * TODO: Why do we just not drop the reference to the lower inode in
    + * ecryptfs_destroy_inode?
    + */
    +static void ecryptfs_clear_inode(struct inode *inode)
    +{
    + ecryptfs_printk(1, KERN_NOTICE, "Enter; inode = [%p]; i_ino = [%lu]\n",
    + inode, inode->i_ino);
    + ecryptfs_iput(INODE_TO_LOWER(inode));
    + ecryptfs_printk(1, KERN_NOTICE, "Exit\n");
    +}
    +
    +/**
    + * 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.
    + *
    + * PS. I wonder if this is somehow useful to undo damage that was
    + * left in the kernel after a user level file server (such as amd)
    + * dies.
    + */
    +static void ecryptfs_umount_begin(struct super_block *sb)
    +{
    + struct super_block *lower_sb;
    + ecryptfs_printk(1, KERN_NOTICE, "Enter\n");
    + /* TODO: Explain why we are umounting the lower superblock */
    + lower_sb = SUPERBLOCK_TO_LOWER(sb);
    + if (lower_sb->s_op->umount_begin)
    + lower_sb->s_op->umount_begin(lower_sb);
    + ecryptfs_printk(1, KERN_NOTICE, "Exit\n");
    +}
    +
    +/* TODO: Where is this normally declared? */
    +int seq_printf(struct seq_file *m, const char *f, ...);
    +
    +/**
    + * Prints the directory we are currently mounted over
    + *
    + * @return 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;
    + int ret = 0;
    + char *tmp = NULL;
    + char *path;
    + ecryptfs_printk(1, KERN_NOTICE, "Enter\n");
    + tmp = (char *)__get_free_page(GFP_KERNEL);
    + if (!tmp) {
    + ret = -ENOMEM;
    + goto out;
    + }
    + /* TODO: wrap? */
    + path = d_path(DENTRY_TO_LOWER(sb->s_root),
    + SUPERBLOCK_TO_PRIVATE(sb)->lower_mnt, tmp, PAGE_SIZE);
    + seq_printf(m, ",dir=%s", path);
    + free_page((unsigned long)tmp);
    + out:
    + ecryptfs_printk(1, KERN_NOTICE, "Exit; ret = [%d]\n",ret);
    + return ret;
    +}
    +
    +/* TODO: Provide operations? (quota stuff, dirty, sync) */
    +struct super_operations ecryptfs_sops = {
    + .alloc_inode = ecryptfs_alloc_inode,
    + .destroy_inode = ecryptfs_destroy_inode,
    + .read_inode = ecryptfs_read_inode,
    + .drop_inode = ecryptfs_drop_inode,
    + .put_super = ecryptfs_put_super,
    + .statfs = ecryptfs_statfs,
    + .remount_fs = ecryptfs_remount_fs,
    + .clear_inode = ecryptfs_clear_inode,
    + .umount_begin = ecryptfs_umount_begin,
    + .show_options = ecryptfs_show_options
    +};
    -
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