JFFS2: Add parameter to reserve disk space for root
Add a new rp_size= parameter which creates a "reserved pool" of disk
space which can only be used by root. Other users are not permitted
to write to disk when the available space is less than the pool size.
Based on original code by Artem Bityutskiy in
https://dev.laptop.org/ticket/5317
[dwmw2: use capable(CAP_SYS_RESOURCE) not uid/gid check, fix debug prints]
Signed-off-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
index f9916f3..66d4456 100644
--- a/fs/jffs2/super.c
+++ b/fs/jffs2/super.c
@@ -105,6 +105,8 @@
if (opts->override_compr)
seq_printf(s, ",compr=%s", jffs2_compr_name(opts->compr));
+ if (opts->rp_size)
+ seq_printf(s, ",rp_size=%u", opts->rp_size / 1024);
return 0;
}
@@ -171,15 +173,18 @@
* JFFS2 mount options.
*
* Opt_override_compr: override default compressor
+ * Opt_rp_size: size of reserved pool in KiB
* Opt_err: just end of array marker
*/
enum {
Opt_override_compr,
+ Opt_rp_size,
Opt_err,
};
static const match_table_t tokens = {
{Opt_override_compr, "compr=%s"},
+ {Opt_rp_size, "rp_size=%u"},
{Opt_err, NULL},
};
@@ -187,6 +192,7 @@
{
substring_t args[MAX_OPT_ARGS];
char *p, *name;
+ unsigned int opt;
if (!data)
return 0;
@@ -224,6 +230,17 @@
kfree(name);
c->mount_opts.override_compr = true;
break;
+ case Opt_rp_size:
+ if (match_int(&args[0], &opt))
+ return -EINVAL;
+ opt *= 1024;
+ if (opt > c->mtd->size) {
+ pr_warn("Too large reserve pool specified, max "
+ "is %llu KB\n", c->mtd->size / 1024);
+ return -EINVAL;
+ }
+ c->mount_opts.rp_size = opt;
+ break;
default:
pr_err("Error: unrecognized mount option '%s' or missing value\n",
p);