[PATCH 2/2] jffs2: fix can't set rp_size to zero during remounting

[Zhe Li]

Maintainer ping?

	Zhe

On Tue, 13 Oct 2020 19:41:30 +0800, Zhe Li wrote:
>
>Set rp_size to zero will be ignore during remounting.
>
>The method to identify whether we input a remounting option of
>rp_size is to check if the rp_size input is zero. It can not work
>well if we pass "rp_size=0".
>
>This patch add a bool variable "set_rp_size" to fix this problem.
>
>By the way, the problem of NULL pointer dereference in rp_size
>fs option parsing showed at
>https://lore.kernel.org/linux-mtd/20201012131204.59102-1-jamie@nuviainc.com/T/#u
>should be applyed before this patch to make sure it works well.
>
>Reported-by: Jubin Zhong <zhongjubin at huawei.com>
>Signed-off-by: lizhe <lizhe67 at huawei.com>
>---
> fs/jffs2/jffs2_fs_sb.h | 1 +
> fs/jffs2/super.c       | 7 +++++--
> 2 files changed, 6 insertions(+), 2 deletions(-)
>
>diff --git a/fs/jffs2/jffs2_fs_sb.h b/fs/jffs2/jffs2_fs_sb.h
>index 778275f48a87..5a7091746f68 100644
>--- a/fs/jffs2/jffs2_fs_sb.h
>+++ b/fs/jffs2/jffs2_fs_sb.h
>@@ -38,6 +38,7 @@ struct jffs2_mount_opts {
> 	 * users. This is implemented simply by means of not allowing the
> 	 * latter users to write to the file system if the amount if the
> 	 * available space is less then 'rp_size'. */
>+	bool set_rp_size;
> 	unsigned int rp_size;
> };
> 
>diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
>index 4fd297bdf0f3..c523adaca79f 100644
>--- a/fs/jffs2/super.c
>+++ b/fs/jffs2/super.c
>@@ -88,7 +88,7 @@ static int jffs2_show_options(struct seq_file *s, struct dentry *root)
> 
> 	if (opts->override_compr)
> 		seq_printf(s, ",compr=%s", jffs2_compr_name(opts->compr));
>-	if (opts->rp_size)
>+	if (opts->set_rp_size)
> 		seq_printf(s, ",rp_size=%u", opts->rp_size / 1024);
> 
> 	return 0;
>@@ -206,6 +206,7 @@ static int jffs2_parse_param(struct fs_context *fc, struct fs_parameter *param)
> 		if (opt > c->mtd->size)
> 			return invalf(fc, "jffs2: Too large reserve pool specified, max is %llu KB",
> 				      c->mtd->size / 1024);
>+		c->mount_opts.set_rp_size = true;
> 		c->mount_opts.rp_size = opt;
> 		break;
> 	default:
>@@ -225,8 +226,10 @@ static inline void jffs2_update_mount_opts(struct fs_context *fc)
> 		c->mount_opts.override_compr = new_c->mount_opts.override_compr;
> 		c->mount_opts.compr = new_c->mount_opts.compr;
> 	}
>-	if (new_c->mount_opts.rp_size)
>+	if (new_c->mount_opts.set_rp_size) {
>+		c->mount_opts.set_rp_size = new_c->mount_opts.set_rp_size;
> 		c->mount_opts.rp_size = new_c->mount_opts.rp_size;
>+	}
> 	mutex_unlock(&c->alloc_sem);
> }
> 
>-- 
>2.12.3
>