inode.c

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/*
 * Persistent Storage - ramfs parts.
 *
 * Copyright (C) 2010 Intel Corporation <[email protected]>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  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
 */

#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/spinlock.h>
#include <linux/uaccess.h>

#include "internal.h"

#define PSTORE_NAMELEN  64

static DEFINE_SPINLOCK(allpstore_lock);
static LIST_HEAD(allpstore);

struct pstore_private {
    struct list_head list;
    struct pstore_info *psi;
    enum pstore_type_id type;
    u64 id;
    ssize_t size;
    char    data[];
};

struct pstore_ftrace_seq_data {
    const void *ptr;
    size_t off;
    size_t size;
};

#define REC_SIZE sizeof(struct pstore_ftrace_record)

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->size % REC_SIZE;
    data->off += *pos * REC_SIZE;
    if (data->off + REC_SIZE > ps->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;

    data->off += REC_SIZE;
    if (data->off + REC_SIZE > ps->size)
        return NULL;

    (*pos)++;
    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 = (void *)(ps->data + data->off);

    seq_printf(s, "%d %08lx  %08lx  %pf <- %pF\n",
        pstore_ftrace_decode_cpu(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->type == PSTORE_TYPE_FTRACE)
        return seq_read(file, userbuf, count, ppos);
    return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->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->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 origin)
{
    struct seq_file *sf = file->private_data;

    if (sf->op)
        return seq_lseek(file, off, origin);
    return default_llseek(file, off, origin);
}

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 = dentry->d_inode->i_private;

    if (p->psi->erase)
        p->psi->erase(p->type, p->id, p->psi);

    return simple_unlink(dir, dentry);
}

static void pstore_evict_inode(struct inode *inode)
{
    struct pstore_private   *p = inode->i_private;
    unsigned long       flags;

    clear_inode(inode);
    if (p) {
        spin_lock_irqsave(&allpstore_lock, flags);
        list_del(&p->list);
        spin_unlock_irqrestore(&allpstore_lock, flags);
        kfree(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->i_ctime = CURRENT_TIME;
    }
    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;
        }
    }
}

static int pstore_remount(struct super_block *sb, int *flags, char *data)
{
    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   = generic_show_options,
};

static struct super_block *pstore_sb;

int pstore_is_mounted(void)
{
    return pstore_sb != NULL;
}

/*
 * 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(enum pstore_type_id type, char *psname, u64 id,
          char *data, size_t size, struct timespec time,
          struct pstore_info *psi)
{
    struct dentry       *root = pstore_sb->s_root;
    struct dentry       *dentry;
    struct inode        *inode;
    int         rc = 0;
    char            name[PSTORE_NAMELEN];
    struct pstore_private   *private, *pos;
    unsigned long       flags;

    spin_lock_irqsave(&allpstore_lock, flags);
    list_for_each_entry(pos, &allpstore, list) {
        if (pos->type == type &&
            pos->id == id &&
            pos->psi == psi) {
            rc = -EEXIST;
            break;
        }
    }
    spin_unlock_irqrestore(&allpstore_lock, flags);
    if (rc)
        return rc;

    rc = -ENOMEM;
    inode = pstore_get_inode(pstore_sb);
    if (!inode)
        goto fail;
    inode->i_mode = S_IFREG | 0444;
    inode->i_fop = &pstore_file_operations;
    private = kmalloc(sizeof *private + size, GFP_KERNEL);
    if (!private)
        goto fail_alloc;
    private->type = type;
    private->id = id;
    private->psi = psi;

    switch (type) {
    case PSTORE_TYPE_DMESG:
        sprintf(name, "dmesg-%s-%lld", psname, id);
        break;
    case PSTORE_TYPE_CONSOLE:
        sprintf(name, "console-%s", psname);
        break;
    case PSTORE_TYPE_FTRACE:
        sprintf(name, "ftrace-%s", psname);
        break;
    case PSTORE_TYPE_MCE:
        sprintf(name, "mce-%s-%lld", psname, id);
        break;
    case PSTORE_TYPE_UNKNOWN:
        sprintf(name, "unknown-%s-%lld", psname, id);
        break;
    default:
        sprintf(name, "type%d-%s-%lld", type, psname, id);
        break;
    }

    mutex_lock(&root->d_inode->i_mutex);

    rc = -ENOSPC;
    dentry = d_alloc_name(root, name);
    if (IS_ERR(dentry))
        goto fail_lockedalloc;

    memcpy(private->data, data, size);
    inode->i_size = private->size = size;

    inode->i_private = private;

    if (time.tv_sec)
        inode->i_mtime = inode->i_ctime = time;

    d_add(dentry, inode);

    spin_lock_irqsave(&allpstore_lock, flags);
    list_add(&private->list, &allpstore);
    spin_unlock_irqrestore(&allpstore_lock, flags);

    mutex_unlock(&root->d_inode->i_mutex);

    return 0;

fail_lockedalloc:
    mutex_unlock(&root->d_inode->i_mutex);
    kfree(private);
fail_alloc:
    iput(inode);

fail:
    return rc;
}

static int pstore_fill_super(struct super_block *sb, void *data, int silent)
{
    struct inode *inode;

    save_mount_options(sb, data);

    pstore_sb = sb;

    sb->s_maxbytes      = MAX_LFS_FILESIZE;
    sb->s_blocksize     = PAGE_CACHE_SIZE;
    sb->s_blocksize_bits    = PAGE_CACHE_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 | 0755;
        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;

    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)
{
    kill_litter_super(sb);
    pstore_sb = NULL;
}

static struct file_system_type pstore_fs_type = {
    .name       = "pstore",
    .mount      = pstore_mount,
    .kill_sb    = pstore_kill_sb,
};

static int __init init_pstore_fs(void)
{
    return register_filesystem(&pstore_fs_type);
}
module_init(init_pstore_fs)

MODULE_AUTHOR("Tony Luck <[email protected]>");
MODULE_LICENSE("GPL");