1 files changed, 377 insertions, 0 deletions
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
new file mode 100644
index 000000000000..e55126f85bd2
--- /dev/null
+++ b/fs/kernfs/inode.c
@@ -0,0 +1,377 @@
+/*
+ * fs/kernfs/inode.c - kernfs inode implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/pagemap.h>
+#include <linux/backing-dev.h>
+#include <linux/capability.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+
+#include "kernfs-internal.h"
+
+static const struct address_space_operations kernfs_aops = {
+	.readpage	= simple_readpage,
+	.write_begin	= simple_write_begin,
+	.write_end	= simple_write_end,
+};
+
+static struct backing_dev_info kernfs_bdi = {
+	.name		= "kernfs",
+	.ra_pages	= 0,	/* No readahead */
+	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
+};
+
+static const struct inode_operations kernfs_iops = {
+	.permission	= kernfs_iop_permission,
+	.setattr	= kernfs_iop_setattr,
+	.getattr	= kernfs_iop_getattr,
+	.setxattr	= kernfs_iop_setxattr,
+	.removexattr	= kernfs_iop_removexattr,
+	.getxattr	= kernfs_iop_getxattr,
+	.listxattr	= kernfs_iop_listxattr,
+};
+
+void __init kernfs_inode_init(void)
+{
+	if (bdi_init(&kernfs_bdi))
+		panic("failed to init kernfs_bdi");
+}
+
+static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
+{
+	struct iattr *iattrs;
+
+	if (kn->iattr)
+		return kn->iattr;
+
+	kn->iattr = kzalloc(sizeof(struct kernfs_iattrs), GFP_KERNEL);
+	if (!kn->iattr)
+		return NULL;
+	iattrs = &kn->iattr->ia_iattr;
+
+	/* assign default attributes */
+	iattrs->ia_mode = kn->mode;
+	iattrs->ia_uid = GLOBAL_ROOT_UID;
+	iattrs->ia_gid = GLOBAL_ROOT_GID;
+	iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
+
+	simple_xattrs_init(&kn->iattr->xattrs);
+
+	return kn->iattr;
+}
+
+static int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
+{
+	struct kernfs_iattrs *attrs;
+	struct iattr *iattrs;
+	unsigned int ia_valid = iattr->ia_valid;
+
+	attrs = kernfs_iattrs(kn);
+	if (!attrs)
+		return -ENOMEM;
+
+	iattrs = &attrs->ia_iattr;
+
+	if (ia_valid & ATTR_UID)
+		iattrs->ia_uid = iattr->ia_uid;
+	if (ia_valid & ATTR_GID)
+		iattrs->ia_gid = iattr->ia_gid;
+	if (ia_valid & ATTR_ATIME)
+		iattrs->ia_atime = iattr->ia_atime;
+	if (ia_valid & ATTR_MTIME)
+		iattrs->ia_mtime = iattr->ia_mtime;
+	if (ia_valid & ATTR_CTIME)
+		iattrs->ia_ctime = iattr->ia_ctime;
+	if (ia_valid & ATTR_MODE) {
+		umode_t mode = iattr->ia_mode;
+		iattrs->ia_mode = kn->mode = mode;
+	}
+	return 0;
+}
+
+/**
+ * kernfs_setattr - set iattr on a node
+ * @kn: target node
+ * @iattr: iattr to set
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
+{
+	int ret;
+
+	mutex_lock(&kernfs_mutex);
+	ret = __kernfs_setattr(kn, iattr);
+	mutex_unlock(&kernfs_mutex);
+	return ret;
+}
+
+int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
+{
+	struct inode *inode = dentry->d_inode;
+	struct kernfs_node *kn = dentry->d_fsdata;
+	int error;
+
+	if (!kn)
+		return -EINVAL;
+
+	mutex_lock(&kernfs_mutex);
+	error = inode_change_ok(inode, iattr);
+	if (error)
+		goto out;
+
+	error = __kernfs_setattr(kn, iattr);
+	if (error)
+		goto out;
+
+	/* this ignores size changes */
+	setattr_copy(inode, iattr);
+
+out:
+	mutex_unlock(&kernfs_mutex);
+	return error;
+}
+
+static int kernfs_node_setsecdata(struct kernfs_node *kn, void **secdata,
+				  u32 *secdata_len)
+{
+	struct kernfs_iattrs *attrs;
+	void *old_secdata;
+	size_t old_secdata_len;
+
+	attrs = kernfs_iattrs(kn);
+	if (!attrs)
+		return -ENOMEM;
+
+	old_secdata = attrs->ia_secdata;
+	old_secdata_len = attrs->ia_secdata_len;
+
+	attrs->ia_secdata = *secdata;
+	attrs->ia_secdata_len = *secdata_len;
+
+	*secdata = old_secdata;
+	*secdata_len = old_secdata_len;
+	return 0;
+}
+
+int kernfs_iop_setxattr(struct dentry *dentry, const char *name,
+			const void *value, size_t size, int flags)
+{
+	struct kernfs_node *kn = dentry->d_fsdata;
+	struct kernfs_iattrs *attrs;
+	void *secdata;
+	int error;
+	u32 secdata_len = 0;
+
+	attrs = kernfs_iattrs(kn);
+	if (!attrs)
+		return -ENOMEM;
+
+	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
+		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
+		error = security_inode_setsecurity(dentry->d_inode, suffix,
+						value, size, flags);
+		if (error)
+			return error;
+		error = security_inode_getsecctx(dentry->d_inode,
+						&secdata, &secdata_len);
+		if (error)
+			return error;
+
+		mutex_lock(&kernfs_mutex);
+		error = kernfs_node_setsecdata(kn, &secdata, &secdata_len);
+		mutex_unlock(&kernfs_mutex);
+
+		if (secdata)
+			security_release_secctx(secdata, secdata_len);
+		return error;
+	} else if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
+		return simple_xattr_set(&attrs->xattrs, name, value, size,
+					flags);
+	}
+
+	return -EINVAL;
+}
+
+int kernfs_iop_removexattr(struct dentry *dentry, const char *name)
+{
+	struct kernfs_node *kn = dentry->d_fsdata;
+	struct kernfs_iattrs *attrs;
+
+	attrs = kernfs_iattrs(kn);
+	if (!attrs)
+		return -ENOMEM;
+
+	return simple_xattr_remove(&attrs->xattrs, name);
+}
+
+ssize_t kernfs_iop_getxattr(struct dentry *dentry, const char *name, void *buf,
+			    size_t size)
+{
+	struct kernfs_node *kn = dentry->d_fsdata;
+	struct kernfs_iattrs *attrs;
+
+	attrs = kernfs_iattrs(kn);
+	if (!attrs)
+		return -ENOMEM;
+
+	return simple_xattr_get(&attrs->xattrs, name, buf, size);
+}
+
+ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
+{
+	struct kernfs_node *kn = dentry->d_fsdata;
+	struct kernfs_iattrs *attrs;
+
+	attrs = kernfs_iattrs(kn);
+	if (!attrs)
+		return -ENOMEM;
+
+	return simple_xattr_list(&attrs->xattrs, buf, size);
+}
+
+static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
+{
+	inode->i_mode = mode;
+	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+}
+
+static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
+{
+	inode->i_uid = iattr->ia_uid;
+	inode->i_gid = iattr->ia_gid;
+	inode->i_atime = iattr->ia_atime;
+	inode->i_mtime = iattr->ia_mtime;
+	inode->i_ctime = iattr->ia_ctime;
+}
+
+static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
+{
+	struct kernfs_iattrs *attrs = kn->iattr;
+
+	inode->i_mode = kn->mode;
+	if (attrs) {
+		/*
+		 * kernfs_node has non-default attributes get them from
+		 * persistent copy in kernfs_node.
+		 */
+		set_inode_attr(inode, &attrs->ia_iattr);
+		security_inode_notifysecctx(inode, attrs->ia_secdata,
+					    attrs->ia_secdata_len);
+	}
+
+	if (kernfs_type(kn) == KERNFS_DIR)
+		set_nlink(inode, kn->dir.subdirs + 2);
+}
+
+int kernfs_iop_getattr(struct vfsmount *mnt, struct dentry *dentry,
+		   struct kstat *stat)
+{
+	struct kernfs_node *kn = dentry->d_fsdata;
+	struct inode *inode = dentry->d_inode;
+
+	mutex_lock(&kernfs_mutex);
+	kernfs_refresh_inode(kn, inode);
+	mutex_unlock(&kernfs_mutex);
+
+	generic_fillattr(inode, stat);
+	return 0;
+}
+
+static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
+{
+	kernfs_get(kn);
+	inode->i_private = kn;
+	inode->i_mapping->a_ops = &kernfs_aops;
+	inode->i_mapping->backing_dev_info = &kernfs_bdi;
+	inode->i_op = &kernfs_iops;
+
+	set_default_inode_attr(inode, kn->mode);
+	kernfs_refresh_inode(kn, inode);
+
+	/* initialize inode according to type */
+	switch (kernfs_type(kn)) {
+	case KERNFS_DIR:
+		inode->i_op = &kernfs_dir_iops;
+		inode->i_fop = &kernfs_dir_fops;
+		break;
+	case KERNFS_FILE:
+		inode->i_size = kn->attr.size;
+		inode->i_fop = &kernfs_file_fops;
+		break;
+	case KERNFS_LINK:
+		inode->i_op = &kernfs_symlink_iops;
+		break;
+	default:
+		BUG();
+	}
+
+	unlock_new_inode(inode);
+}
+
+/**
+ *	kernfs_get_inode - get inode for kernfs_node
+ *	@sb: super block
+ *	@kn: kernfs_node to allocate inode for
+ *
+ *	Get inode for @kn.  If such inode doesn't exist, a new inode is
+ *	allocated and basics are initialized.  New inode is returned
+ *	locked.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	Pointer to allocated inode on success, NULL on failure.
+ */
+struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
+{
+	struct inode *inode;
+
+	inode = iget_locked(sb, kn->ino);
+	if (inode && (inode->i_state & I_NEW))
+		kernfs_init_inode(kn, inode);
+
+	return inode;
+}
+
+/*
+ * The kernfs_node serves as both an inode and a directory entry for
+ * kernfs.  To prevent the kernfs inode numbers from being freed
+ * prematurely we take a reference to kernfs_node from the kernfs inode.  A
+ * super_operations.evict_inode() implementation is needed to drop that
+ * reference upon inode destruction.
+ */
+void kernfs_evict_inode(struct inode *inode)
+{
+	struct kernfs_node *kn = inode->i_private;
+
+	truncate_inode_pages(&inode->i_data, 0);
+	clear_inode(inode);
+	kernfs_put(kn);
+}
+
+int kernfs_iop_permission(struct inode *inode, int mask)
+{
+	struct kernfs_node *kn;
+
+	if (mask & MAY_NOT_BLOCK)
+		return -ECHILD;
+
+	kn = inode->i_private;
+
+	mutex_lock(&kernfs_mutex);
+	kernfs_refresh_inode(kn, inode);
+	mutex_unlock(&kernfs_mutex);
+
+	return generic_permission(inode, mask);
+}