Commit f8feafea authored by Kees Cook's avatar Kees Cook
Browse files

pstore/blk: Introduce "best_effort" mode 

In order to use arbitrary block devices as a pstore backend, provide a
new module param named "best_effort", which will allow using any block
device, even if it has not provided a panic_write callback.

Link: https://lore.kernel.org/lkml/20200511233229.27745-12-keescook@chromium.org/


Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent 7dcb7848

fs/pstore/blk.c

+20 −1
Original line number Diff line number Diff line
@@ -51,6 +51,10 @@ static long ftrace_size = -1; 
module_param(ftrace_size, long, 0400);

MODULE_PARM_DESC(ftrace_size, "ftrace size in kbytes");



static bool best_effort;

module_param(best_effort, bool, 0400);

MODULE_PARM_DESC(best_effort, "use best effort to write (i.e. do not require storage driver pstore support, default: off)");



/*

 * blkdev - the block device to use for pstore storage

 *
@@ -374,7 +378,8 @@ static int __register_pstore_blk(struct pstore_blk_info *info) 
	}



	/* only allow driver matching the @blkdev */

	if (!binfo.devt || MAJOR(binfo.devt) != info->major) {

	if (!binfo.devt || (!best_effort &&

			    MAJOR(binfo.devt) != info->major)) {

		pr_debug("invalid major %u (expect %u)\n",

				info->major, MAJOR(binfo.devt));

		ret = -ENODEV;
@@ -476,6 +481,20 @@ int pstore_blk_get_config(struct pstore_blk_config *info) 
}

EXPORT_SYMBOL_GPL(pstore_blk_get_config);



static int __init pstore_blk_init(void)

{

	struct pstore_blk_info info = { };

	int ret = 0;



	mutex_lock(&pstore_blk_lock);

	if (!pstore_zone_info && best_effort && blkdev[0])

		ret = __register_pstore_blk(&info);

	mutex_unlock(&pstore_blk_lock);



	return ret;

}

late_initcall(pstore_blk_init);



static void __exit pstore_blk_exit(void)

{

	mutex_lock(&pstore_blk_lock);

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