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pstore/blk: Introduce "best_effort" mode

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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: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2020-05-08 08:34:01 -07:00
parent 7dcb7848ba
commit f8feafeaee
1 changed files with 20 additions and 1 deletions
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21
fs/pstore/blk.c
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@ -51,6 +51,10 @@ static long ftrace_size = -1;
module_param(ftrace_size, long, 0400); module_param(ftrace_size, long, 0400);
MODULE_PARM_DESC(ftrace_size, "ftrace size in kbytes"); 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 * 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 */ /* 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", pr_debug("invalid major %u (expect %u)\n",
info->major, MAJOR(binfo.devt)); info->major, MAJOR(binfo.devt));
ret = -ENODEV; ret = -ENODEV;
@ -476,6 +481,20 @@ int pstore_blk_get_config(struct pstore_blk_config *info)
} }
EXPORT_SYMBOL_GPL(pstore_blk_get_config); 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) static void __exit pstore_blk_exit(void)
{ {
mutex_lock(&pstore_blk_lock); mutex_lock(&pstore_blk_lock);