pstore: add pstore unregister

pstore doesn't support unregistering yet. It was marked as TODO.
This patch adds some code to fix it:
 1) Add functions to unregister kmsg/console/ftrace/pmsg.
 2) Add a function to free compression buffer.
 3) Unmap the memory and free it.
 4) Add a function to unregister pstore filesystem.

Signed-off-by: Geliang Tang <geliangtang@163.com>
Acked-by: Kees Cook <keescook@chromium.org>
[Removed __exit annotation from ramoops_remove(). Reported by Arnd Bergmann]
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 3adcc4669fac..3586491f26ba 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -178,6 +178,7 @@ static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
 }
 
 static const struct file_operations pstore_file_operations = {
+	.owner		= THIS_MODULE,
 	.open		= pstore_file_open,
 	.read		= pstore_file_read,
 	.llseek		= pstore_file_llseek,
@@ -456,6 +457,7 @@ static void pstore_kill_sb(struct super_block *sb)
 }
 
 static struct file_system_type pstore_fs_type = {
+	.owner          = THIS_MODULE,
 	.name		= "pstore",
 	.mount		= pstore_mount,
 	.kill_sb	= pstore_kill_sb,
@@ -479,5 +481,12 @@ out:
 }
 module_init(init_pstore_fs)
 
+static void __exit exit_pstore_fs(void)
+{
+	unregister_filesystem(&pstore_fs_type);
+	sysfs_remove_mount_point(fs_kobj, "pstore");
+}
+module_exit(exit_pstore_fs)
+
 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 MODULE_LICENSE("GPL");