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);
+}