1 files changed, 511 insertions, 0 deletions
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
new file mode 100644
index 0000000000..585360706b
--- /dev/null
+++ b/fs/pstore/inode.c
@@ -0,0 +1,511 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Persistent Storage - ramfs parts.
+ *
+ * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/fsnotify.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/string.h>
+#include <linux/mount.h>
+#include <linux/seq_file.h>
+#include <linux/ramfs.h>
+#include <linux/parser.h>
+#include <linux/sched.h>
+#include <linux/magic.h>
+#include <linux/pstore.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+
+#include "internal.h"
+
+#define	PSTORE_NAMELEN	64
+
+static DEFINE_MUTEX(records_list_lock);
+static LIST_HEAD(records_list);
+
+static DEFINE_MUTEX(pstore_sb_lock);
+static struct super_block *pstore_sb;
+
+struct pstore_private {
+	struct list_head list;
+	struct dentry *dentry;
+	struct pstore_record *record;
+	size_t total_size;
+};
+
+struct pstore_ftrace_seq_data {
+	const void *ptr;
+	size_t off;
+	size_t size;
+};
+
+#define REC_SIZE sizeof(struct pstore_ftrace_record)
+
+static void free_pstore_private(struct pstore_private *private)
+{
+	if (!private)
+		return;
+	if (private->record) {
+		kvfree(private->record->buf);
+		kfree(private->record->priv);
+		kfree(private->record);
+	}
+	kfree(private);
+}
+
+static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
+{
+	struct pstore_private *ps = s->private;
+	struct pstore_ftrace_seq_data *data;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return NULL;
+
+	data->off = ps->total_size % REC_SIZE;
+	data->off += *pos * REC_SIZE;
+	if (data->off + REC_SIZE > ps->total_size) {
+		kfree(data);
+		return NULL;
+	}
+
+	return data;
+
+}
+
+static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
+{
+	kfree(v);
+}
+
+static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct pstore_private *ps = s->private;
+	struct pstore_ftrace_seq_data *data = v;
+
+	(*pos)++;
+	data->off += REC_SIZE;
+	if (data->off + REC_SIZE > ps->total_size)
+		return NULL;
+
+	return data;
+}
+
+static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
+{
+	struct pstore_private *ps = s->private;
+	struct pstore_ftrace_seq_data *data = v;
+	struct pstore_ftrace_record *rec;
+
+	if (!data)
+		return 0;
+
+	rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
+
+	seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %ps <- %pS\n",
+		   pstore_ftrace_decode_cpu(rec),
+		   pstore_ftrace_read_timestamp(rec),
+		   rec->ip, rec->parent_ip, (void *)rec->ip,
+		   (void *)rec->parent_ip);
+
+	return 0;
+}
+
+static const struct seq_operations pstore_ftrace_seq_ops = {
+	.start	= pstore_ftrace_seq_start,
+	.next	= pstore_ftrace_seq_next,
+	.stop	= pstore_ftrace_seq_stop,
+	.show	= pstore_ftrace_seq_show,
+};
+
+static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
+						size_t count, loff_t *ppos)
+{
+	struct seq_file *sf = file->private_data;
+	struct pstore_private *ps = sf->private;
+
+	if (ps->record->type == PSTORE_TYPE_FTRACE)
+		return seq_read(file, userbuf, count, ppos);
+	return simple_read_from_buffer(userbuf, count, ppos,
+				       ps->record->buf, ps->total_size);
+}
+
+static int pstore_file_open(struct inode *inode, struct file *file)
+{
+	struct pstore_private *ps = inode->i_private;
+	struct seq_file *sf;
+	int err;
+	const struct seq_operations *sops = NULL;
+
+	if (ps->record->type == PSTORE_TYPE_FTRACE)
+		sops = &pstore_ftrace_seq_ops;
+
+	err = seq_open(file, sops);
+	if (err < 0)
+		return err;
+
+	sf = file->private_data;
+	sf->private = ps;
+
+	return 0;
+}
+
+static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
+{
+	struct seq_file *sf = file->private_data;
+
+	if (sf->op)
+		return seq_lseek(file, off, whence);
+	return default_llseek(file, off, whence);
+}
+
+static const struct file_operations pstore_file_operations = {
+	.open		= pstore_file_open,
+	.read		= pstore_file_read,
+	.llseek		= pstore_file_llseek,
+	.release	= seq_release,
+};
+
+/*
+ * When a file is unlinked from our file system we call the
+ * platform driver to erase the record from persistent store.
+ */
+static int pstore_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct pstore_private *p = d_inode(dentry)->i_private;
+	struct pstore_record *record = p->record;
+	int rc = 0;
+
+	if (!record->psi->erase)
+		return -EPERM;
+
+	/* Make sure we can't race while removing this file. */
+	mutex_lock(&records_list_lock);
+	if (!list_empty(&p->list))
+		list_del_init(&p->list);
+	else
+		rc = -ENOENT;
+	p->dentry = NULL;
+	mutex_unlock(&records_list_lock);
+	if (rc)
+		return rc;
+
+	mutex_lock(&record->psi->read_mutex);
+	record->psi->erase(record);
+	mutex_unlock(&record->psi->read_mutex);
+
+	return simple_unlink(dir, dentry);
+}
+
+static void pstore_evict_inode(struct inode *inode)
+{
+	struct pstore_private	*p = inode->i_private;
+
+	clear_inode(inode);
+	free_pstore_private(p);
+}
+
+static const struct inode_operations pstore_dir_inode_operations = {
+	.lookup		= simple_lookup,
+	.unlink		= pstore_unlink,
+};
+
+static struct inode *pstore_get_inode(struct super_block *sb)
+{
+	struct inode *inode = new_inode(sb);
+	if (inode) {
+		inode->i_ino = get_next_ino();
+		inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode);
+	}
+	return inode;
+}
+
+enum {
+	Opt_kmsg_bytes, Opt_err
+};
+
+static const match_table_t tokens = {
+	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
+	{Opt_err, NULL}
+};
+
+static void parse_options(char *options)
+{
+	char		*p;
+	substring_t	args[MAX_OPT_ARGS];
+	int		option;
+
+	if (!options)
+		return;
+
+	while ((p = strsep(&options, ",")) != NULL) {
+		int token;
+
+		if (!*p)
+			continue;
+
+		token = match_token(p, tokens, args);
+		switch (token) {
+		case Opt_kmsg_bytes:
+			if (!match_int(&args[0], &option))
+				pstore_set_kmsg_bytes(option);
+			break;
+		}
+	}
+}
+
+/*
+ * Display the mount options in /proc/mounts.
+ */
+static int pstore_show_options(struct seq_file *m, struct dentry *root)
+{
+	if (kmsg_bytes != CONFIG_PSTORE_DEFAULT_KMSG_BYTES)
+		seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
+	return 0;
+}
+
+static int pstore_remount(struct super_block *sb, int *flags, char *data)
+{
+	sync_filesystem(sb);
+	parse_options(data);
+
+	return 0;
+}
+
+static const struct super_operations pstore_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= generic_delete_inode,
+	.evict_inode	= pstore_evict_inode,
+	.remount_fs	= pstore_remount,
+	.show_options	= pstore_show_options,
+};
+
+static struct dentry *psinfo_lock_root(void)
+{
+	struct dentry *root;
+
+	mutex_lock(&pstore_sb_lock);
+	/*
+	 * Having no backend is fine -- no records appear.
+	 * Not being mounted is fine -- nothing to do.
+	 */
+	if (!psinfo || !pstore_sb) {
+		mutex_unlock(&pstore_sb_lock);
+		return NULL;
+	}
+
+	root = pstore_sb->s_root;
+	inode_lock(d_inode(root));
+	mutex_unlock(&pstore_sb_lock);
+
+	return root;
+}
+
+int pstore_put_backend_records(struct pstore_info *psi)
+{
+	struct pstore_private *pos, *tmp;
+	struct dentry *root;
+	int rc = 0;
+
+	root = psinfo_lock_root();
+	if (!root)
+		return 0;
+
+	mutex_lock(&records_list_lock);
+	list_for_each_entry_safe(pos, tmp, &records_list, list) {
+		if (pos->record->psi == psi) {
+			list_del_init(&pos->list);
+			rc = simple_unlink(d_inode(root), pos->dentry);
+			if (WARN_ON(rc))
+				break;
+			d_drop(pos->dentry);
+			dput(pos->dentry);
+			pos->dentry = NULL;
+		}
+	}
+	mutex_unlock(&records_list_lock);
+
+	inode_unlock(d_inode(root));
+
+	return rc;
+}
+
+/*
+ * Make a regular file in the root directory of our file system.
+ * Load it up with "size" bytes of data from "buf".
+ * Set the mtime & ctime to the date that this record was originally stored.
+ */
+int pstore_mkfile(struct dentry *root, struct pstore_record *record)
+{
+	struct dentry		*dentry;
+	struct inode		*inode;
+	int			rc = 0;
+	char			name[PSTORE_NAMELEN];
+	struct pstore_private	*private, *pos;
+	size_t			size = record->size + record->ecc_notice_size;
+
+	if (WARN_ON(!inode_is_locked(d_inode(root))))
+		return -EINVAL;
+
+	rc = -EEXIST;
+	/* Skip records that are already present in the filesystem. */
+	mutex_lock(&records_list_lock);
+	list_for_each_entry(pos, &records_list, list) {
+		if (pos->record->type == record->type &&
+		    pos->record->id == record->id &&
+		    pos->record->psi == record->psi)
+			goto fail;
+	}
+
+	rc = -ENOMEM;
+	inode = pstore_get_inode(root->d_sb);
+	if (!inode)
+		goto fail;
+	inode->i_mode = S_IFREG | 0444;
+	inode->i_fop = &pstore_file_operations;
+	scnprintf(name, sizeof(name), "%s-%s-%llu%s",
+			pstore_type_to_name(record->type),
+			record->psi->name, record->id,
+			record->compressed ? ".enc.z" : "");
+
+	private = kzalloc(sizeof(*private), GFP_KERNEL);
+	if (!private)
+		goto fail_inode;
+
+	dentry = d_alloc_name(root, name);
+	if (!dentry)
+		goto fail_private;
+
+	private->dentry = dentry;
+	private->record = record;
+	inode->i_size = private->total_size = size;
+	inode->i_private = private;
+
+	if (record->time.tv_sec)
+		inode->i_mtime = inode_set_ctime_to_ts(inode, record->time);
+
+	d_add(dentry, inode);
+
+	list_add(&private->list, &records_list);
+	mutex_unlock(&records_list_lock);
+
+	return 0;
+
+fail_private:
+	free_pstore_private(private);
+fail_inode:
+	iput(inode);
+fail:
+	mutex_unlock(&records_list_lock);
+	return rc;
+}
+
+/*
+ * Read all the records from the persistent store. Create
+ * files in our filesystem.  Don't warn about -EEXIST errors
+ * when we are re-scanning the backing store looking to add new
+ * error records.
+ */
+void pstore_get_records(int quiet)
+{
+	struct dentry *root;
+
+	root = psinfo_lock_root();
+	if (!root)
+		return;
+
+	pstore_get_backend_records(psinfo, root, quiet);
+	inode_unlock(d_inode(root));
+}
+
+static int pstore_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct inode *inode;
+
+	sb->s_maxbytes		= MAX_LFS_FILESIZE;
+	sb->s_blocksize		= PAGE_SIZE;
+	sb->s_blocksize_bits	= PAGE_SHIFT;
+	sb->s_magic		= PSTOREFS_MAGIC;
+	sb->s_op		= &pstore_ops;
+	sb->s_time_gran		= 1;
+
+	parse_options(data);
+
+	inode = pstore_get_inode(sb);
+	if (inode) {
+		inode->i_mode = S_IFDIR | 0750;
+		inode->i_op = &pstore_dir_inode_operations;
+		inode->i_fop = &simple_dir_operations;
+		inc_nlink(inode);
+	}
+	sb->s_root = d_make_root(inode);
+	if (!sb->s_root)
+		return -ENOMEM;
+
+	mutex_lock(&pstore_sb_lock);
+	pstore_sb = sb;
+	mutex_unlock(&pstore_sb_lock);
+
+	pstore_get_records(0);
+
+	return 0;
+}
+
+static struct dentry *pstore_mount(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data)
+{
+	return mount_single(fs_type, flags, data, pstore_fill_super);
+}
+
+static void pstore_kill_sb(struct super_block *sb)
+{
+	mutex_lock(&pstore_sb_lock);
+	WARN_ON(pstore_sb && pstore_sb != sb);
+
+	kill_litter_super(sb);
+	pstore_sb = NULL;
+
+	mutex_lock(&records_list_lock);
+	INIT_LIST_HEAD(&records_list);
+	mutex_unlock(&records_list_lock);
+
+	mutex_unlock(&pstore_sb_lock);
+}
+
+static struct file_system_type pstore_fs_type = {
+	.owner          = THIS_MODULE,
+	.name		= "pstore",
+	.mount		= pstore_mount,
+	.kill_sb	= pstore_kill_sb,
+};
+
+int __init pstore_init_fs(void)
+{
+	int err;
+
+	/* Create a convenient mount point for people to access pstore */
+	err = sysfs_create_mount_point(fs_kobj, "pstore");
+	if (err)
+		goto out;
+
+	err = register_filesystem(&pstore_fs_type);
+	if (err < 0)
+		sysfs_remove_mount_point(fs_kobj, "pstore");
+
+out:
+	return err;
+}
+
+void __exit pstore_exit_fs(void)
+{
+	unregister_filesystem(&pstore_fs_type);
+	sysfs_remove_mount_point(fs_kobj, "pstore");
+}