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    SubjectRe: [PATCH 6/13: eCryptfs] Superblock operations
    Hi Phillip,

    Some comments below.

    On 5/4/06, Phillip Hellewell <phillip@hellewell.homeip.net> wrote:
    > +kmem_cache_t *ecryptfs_inode_info_cache;

    Please use struct kmem_cache instead of the typedef.

    > +static struct inode *ecryptfs_alloc_inode(struct super_block *sb) {

    Formatting

    > + struct ecryptfs_inode_info *ecryptfs_inode = NULL;

    Redundant initialization

    > + struct inode *inode = NULL;
    > +
    > + ecryptfs_printk(KERN_DEBUG, "Enter; sb = [%p]\n", sb);
    > + ecryptfs_inode = kmem_cache_alloc(ecryptfs_inode_info_cache,
    > + SLAB_KERNEL);
    > + if (unlikely(!ecryptfs_inode)) {
    > + ecryptfs_printk(KERN_WARNING,
    > + "Failed to allocate new inode\n");
    > + goto out;

    No need to log it, just return NULL here

    > + }
    > + ecryptfs_init_crypt_stat(&(ecryptfs_inode->crypt_stat));
    > + inode = &(ecryptfs_inode->vfs_inode);

    Bogus parenthesis, twice. Inode is a redundant local variable, btw.

    > +out:
    > + ecryptfs_printk(KERN_DEBUG, "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_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) {

    Formatting

    > + struct ecryptfs_crypt_stat *crypt_stat;
    > +
    > + ecryptfs_printk(KERN_DEBUG, "Enter; inode = [%p]\n", inode);
    > + crypt_stat = &(ECRYPTFS_INODE_TO_PRIVATE(inode))->crypt_stat;
    > + ecryptfs_destruct_crypt_stat(crypt_stat);
    > + kmem_cache_free(ecryptfs_inode_info_cache,
    > + ECRYPTFS_INODE_TO_PRIVATE(inode));

    Better to introduce a local variable for CRYPTFS_INODE_TO_PRIVATE.
    More readable and smaller kernel text that way.

    > + ecryptfs_printk(KERN_DEBUG, "Exit\n");
    > +}
    > +
    > +/**
    > + * Set up the ecryptfs inode.
    > + */
    > +static void ecryptfs_read_inode(struct inode *inode)
    > +{
    > + ecryptfs_printk(KERN_DEBUG, "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. */
    > + ECRYPTFS_INODE_TO_PRIVATE_SM(inode) =
    > + list_entry(inode, struct ecryptfs_inode_info, vfs_inode);
    > + ECRYPTFS_INODE_TO_LOWER(inode) = NULL;

    Hmm, ugly, please make the setters explicit instead.

    > + inode->i_version++;
    > + inode->i_op = &ecryptfs_main_iops;
    > + inode->i_fop = &ecryptfs_main_fops;
    > + inode->i_mapping->a_ops = &ecryptfs_aops;
    > + ecryptfs_printk(KERN_DEBUG, "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) {

    Formatting

    > + 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 = ECRYPTFS_SUPERBLOCK_TO_PRIVATE(sb);

    You probably want to rename ECRYPTFS_SUPERBLOCK_TO_PRIVATE to
    ecryptfs_sb or similar.

    > +
    > + ecryptfs_printk(KERN_DEBUG, "Enter\n");
    > + 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_SUPERBLOCK_TO_PRIVATE_SM(sb) = NULL;
    > + ecryptfs_printk(KERN_DEBUG, "Exit\n");
    > +}
    > +
    > +/**
    > + * Get the filesystem statistics. Currently, we let this pass right through
    > + * to the lower filesystem and take no action ourselves.
    > + */
    > +static int ecryptfs_statfs(struct super_block *sb, struct kstatfs *buf)
    > +{
    > + int rc = 0;

    Redundant initialization

    > +
    > + ecryptfs_printk(KERN_DEBUG, "Enter\n");
    > + rc = vfs_statfs(ECRYPTFS_SUPERBLOCK_TO_LOWER(sb), buf);
    > + ecryptfs_printk(KERN_DEBUG, "Exit; rc = [%d]\n", rc);
    > + return rc;
    > +}
    > +
    > +/**
    > + * Called to ask filesystem to change mount options. Not implemented;
    > + * returns -ENOSYS every time.
    > + */
    > +static int ecryptfs_remount_fs(struct super_block *sb, int *flags, char *data)
    > +{
    > + ecryptfs_printk(KERN_DEBUG, "Enter\n");
    > + ecryptfs_printk(KERN_DEBUG, "Exit\n");
    > + return -ENOSYS;
    > +}

    Any reason you want to keep this around?

    > +
    > +/**
    > + * 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 void ecryptfs_clear_inode(struct inode *inode)
    > +{
    > + ecryptfs_printk(KERN_DEBUG, "Enter; inode = [%p]; i_ino = [0x%.16x]\n",
    > + inode, inode->i_ino);
    > + iput(ECRYPTFS_INODE_TO_LOWER(inode));
    > + ecryptfs_printk(KERN_DEBUG, "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.
    > + */
    > +static void ecryptfs_umount_begin(struct vfsmount *vfsmnt, int flags)
    > +{
    > + struct vfsmount *lower_mnt;
    > + struct super_block *lower_sb;
    > +
    > + ecryptfs_printk(KERN_DEBUG, "Enter\n");
    > + 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_printk(KERN_DEBUG, "Exit\n");
    > +}
    > +
    > +/**
    > + * 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 rc = 0;
    > + char *tmp = NULL;
    > + char *path;
    > +
    > + ecryptfs_printk(KERN_DEBUG, "Enter\n");
    > + tmp = (char *)__get_free_page(GFP_KERNEL);
    > + if (!tmp) {
    > + rc = -ENOMEM;
    > + goto out;
    > + }
    > + path = d_path(ECRYPTFS_DENTRY_TO_LOWER(sb->s_root),
    > + ECRYPTFS_SUPERBLOCK_TO_PRIVATE(sb)->lower_mnt, tmp,
    > + PAGE_SIZE);

    Use of local variables probably would clean that up

    > + seq_printf(m, ",dir=%s", path);
    > + free_page((unsigned long)tmp);
    > +out:
    > + ecryptfs_printk(KERN_DEBUG, "Exit; rc = [%d]\n", rc);
    > + return rc;
    > +}
    > +
    > +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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