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authorTony Luck <tony.luck@intel.com>2010-12-28 14:25:21 -0800
committerTony Luck <tony.luck@intel.com>2010-12-28 14:25:21 -0800
commitca01d6dd2d7a2652000307520777538740efc286 (patch)
treef419325637badb0ef7a3bfa29d520be2f5282220 /fs/pstore/inode.c
parent90a8a73c06cc32b609a880d48449d7083327e11a (diff)
downloadop-kernel-dev-ca01d6dd2d7a2652000307520777538740efc286.zip
op-kernel-dev-ca01d6dd2d7a2652000307520777538740efc286.tar.gz
pstore: new filesystem interface to platform persistent storage
Some platforms have a small amount of non-volatile storage that can be used to store information useful to diagnose the cause of a system crash. This is the generic part of a file system interface that presents information from the crash as a series of files in /dev/pstore. Once the information has been seen, the underlying storage is freed by deleting the files. Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'fs/pstore/inode.c')
-rw-r--r--fs/pstore/inode.c280
1 files changed, 280 insertions, 0 deletions
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
new file mode 100644
index 0000000..0e806aa
--- /dev/null
+++ b/fs/pstore/inode.c
@@ -0,0 +1,280 @@
+/*
+ * Persistent Storage - ramfs parts.
+ *
+ * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
+ *
+ * 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/string.h>
+#include <linux/mount.h>
+#include <linux/ramfs.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
+
+struct pstore_private {
+ u64 id;
+ int (*erase)(u64);
+};
+
+#define pstore_get_inode ramfs_get_inode
+
+/*
+ * 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;
+
+ p->erase(p->id);
+ kfree(p);
+
+ return simple_unlink(dir, dentry);
+}
+
+static const struct inode_operations pstore_dir_inode_operations = {
+ .lookup = simple_lookup,
+ .unlink = pstore_unlink,
+};
+
+static const struct super_operations pstore_ops = {
+ .statfs = simple_statfs,
+ .drop_inode = generic_delete_inode,
+ .show_options = generic_show_options,
+};
+
+static struct super_block *pstore_sb;
+static struct vfsmount *pstore_mnt;
+
+int pstore_is_mounted(void)
+{
+ return pstore_mnt != NULL;
+}
+
+/*
+ * Set up a file structure as if we had opened this file and
+ * write our data to it.
+ */
+static int pstore_writefile(struct inode *inode, struct dentry *dentry,
+ char *data, size_t size)
+{
+ struct file f;
+ ssize_t n;
+ mm_segment_t old_fs = get_fs();
+
+ memset(&f, '0', sizeof f);
+ f.f_mapping = inode->i_mapping;
+ f.f_path.dentry = dentry;
+ f.f_path.mnt = pstore_mnt;
+ f.f_pos = 0;
+ f.f_op = inode->i_fop;
+ set_fs(KERNEL_DS);
+ n = do_sync_write(&f, data, size, &f.f_pos);
+ set_fs(old_fs);
+
+ fsnotify_modify(&f);
+
+ return n == size;
+}
+
+/*
+ * 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, int (*erase)(u64))
+{
+ struct dentry *root = pstore_sb->s_root;
+ struct dentry *dentry;
+ struct inode *inode;
+ int rc;
+ char name[PSTORE_NAMELEN];
+ struct pstore_private *private;
+
+ rc = -ENOMEM;
+ inode = pstore_get_inode(pstore_sb, root->d_inode, S_IFREG | 0444, 0);
+ if (!inode)
+ goto fail;
+ inode->i_uid = inode->i_gid = 0;
+ private = kmalloc(sizeof *private, GFP_KERNEL);
+ if (!private)
+ goto fail_alloc;
+ private->id = id;
+ private->erase = erase;
+
+ switch (type) {
+ case PSTORE_TYPE_DMESG:
+ sprintf(name, "dmesg-%s-%lld", psname, id);
+ 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;
+
+ d_add(dentry, inode);
+
+ mutex_unlock(&root->d_inode->i_mutex);
+
+ if (!pstore_writefile(inode, dentry, data, size))
+ goto fail_write;
+
+ inode->i_private = private;
+
+ if (time.tv_sec)
+ inode->i_mtime = inode->i_ctime = time;
+
+ return 0;
+
+fail_write:
+ kfree(private);
+ inode->i_nlink--;
+ mutex_lock(&root->d_inode->i_mutex);
+ d_delete(dentry);
+ dput(dentry);
+ mutex_unlock(&root->d_inode->i_mutex);
+ goto fail;
+
+fail_lockedalloc:
+ mutex_unlock(&root->d_inode->i_mutex);
+ kfree(private);
+fail_alloc:
+ iput(inode);
+
+fail:
+ return rc;
+}
+
+int pstore_fill_super(struct super_block *sb, void *data, int silent)
+{
+ struct inode *inode = NULL;
+ struct dentry *root;
+ int err;
+
+ 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;
+
+ inode = pstore_get_inode(sb, NULL, S_IFDIR | 0755, 0);
+ if (!inode) {
+ err = -ENOMEM;
+ goto fail;
+ }
+ /* override ramfs "dir" options so we catch unlink(2) */
+ inode->i_op = &pstore_dir_inode_operations;
+
+ root = d_alloc_root(inode);
+ sb->s_root = root;
+ if (!root) {
+ err = -ENOMEM;
+ goto fail;
+ }
+
+ pstore_get_records();
+
+ return 0;
+fail:
+ iput(inode);
+ return err;
+}
+
+static int pstore_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data, struct vfsmount *mnt)
+{
+ struct dentry *root;
+
+ root = mount_nodev(fs_type, flags, data, pstore_fill_super);
+ if (IS_ERR(root))
+ return -ENOMEM;
+
+ mnt->mnt_root = root;
+ mnt->mnt_sb = root->d_sb;
+ pstore_mnt = mnt;
+
+ return 0;
+}
+
+static void pstore_kill_sb(struct super_block *sb)
+{
+ kill_litter_super(sb);
+ pstore_sb = NULL;
+ pstore_mnt = NULL;
+}
+
+static struct file_system_type pstore_fs_type = {
+ .name = "pstore",
+ .get_sb = pstore_get_sb,
+ .kill_sb = pstore_kill_sb,
+};
+
+static int __init init_pstore_fs(void)
+{
+ int ret = 0;
+ struct kobject *pstorefs_kobj;
+
+ pstorefs_kobj = kobject_create_and_add("pstore", fs_kobj);
+ if (!pstorefs_kobj)
+ return -ENOMEM;
+
+ sysfs_create_file(pstorefs_kobj, &pstore_kmsg_bytes_attr.attr);
+
+ ret = register_filesystem(&pstore_fs_type);
+
+ if (ret) {
+ sysfs_remove_file(pstorefs_kobj, &pstore_kmsg_bytes_attr.attr);
+ kobject_put(pstorefs_kobj);
+ }
+
+ return ret;
+}
+module_init(init_pstore_fs)
+
+MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
+MODULE_LICENSE("GPL");
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