From a7a8f4a1e6b309b5365be784a07bbda1ceab2d9e Mon Sep 17 00:00:00 2001 From: Martin Kaistra Date: Tue, 7 Jul 2020 12:31:59 +0200 Subject: ubifs: add option to specify version for new file systems Instead of creating ubifs file systems with UBIFS_FORMAT_VERSION by default, add a module parameter ubifs.default_version to allow the user to specify the desired version. Valid values are 4 to UBIFS_FORMAT_VERSION (currently 5). This way, one can for example create a file system with version 4 on kernel 4.19 which can still be mounted rw when downgrading to kernel 4.9. Signed-off-by: Martin Kaistra Signed-off-by: Richard Weinberger --- fs/ubifs/super.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'fs/ubifs/super.c') diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c index 7fc2f3f07c16..a2420c900275 100644 --- a/fs/ubifs/super.c +++ b/fs/ubifs/super.c @@ -26,6 +26,24 @@ #include #include "ubifs.h" +static int ubifs_default_version_set(const char *val, const struct kernel_param *kp) +{ + int n = 0, ret; + + ret = kstrtoint(val, 10, &n); + if (ret != 0 || n < 4 || n > UBIFS_FORMAT_VERSION) + return -EINVAL; + return param_set_int(val, kp); +} + +static const struct kernel_param_ops ubifs_default_version_ops = { + .set = ubifs_default_version_set, + .get = param_get_int, +}; + +int ubifs_default_version = UBIFS_FORMAT_VERSION; +module_param_cb(default_version, &ubifs_default_version_ops, &ubifs_default_version, 0600); + /* * Maximum amount of memory we may 'kmalloc()' without worrying that we are * allocating too much. -- cgit