[PATCH v3 4/4] staging: erofs: option validation in remount

[Chengguang Xu]

Add option validation in remount. After this patch, remount
can change recognized options, and for unknown options remount
will fail and report error.

Signed-off-by: Chengguang Xu <cgxu...@gmx.com>
Reviewed-by: Chao Yu <yuch...@huawei.com>
---
 drivers/staging/erofs/super.c | 38 ++++++++++++++++++++++++++++-------
 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c
index a091b93190e1..30b6b44dc6c4 100644
--- a/drivers/staging/erofs/super.c
+++ b/drivers/staging/erofs/super.c
@@ -145,14 +145,10 @@ char *erofs_fault_name[FAULT_MAX] = {
        [FAULT_KMALLOC]         = "kmalloc",
 };
 
-static int erofs_build_fault_attr(struct erofs_sb_info *sbi,
-                                       substring_t *args)
+static void __erofs_build_fault_attr(struct erofs_sb_info *sbi,
+                                               unsigned int rate)
 {
        struct erofs_fault_info *ffi = &sbi->fault_info;
-       int rate = 0;
-
-       if (args->from && match_int(args, &rate))
-               return -EINVAL;
 
        if (rate) {
                atomic_set(&ffi->inject_ops, 0);
@@ -163,14 +159,29 @@ static int erofs_build_fault_attr(struct erofs_sb_info 
*sbi,
        }
 
        set_opt(sbi, FAULT_INJECTION);
-       return 0;
 }
 
 static unsigned int erofs_get_fault_rate(struct erofs_sb_info *sbi)
 {
        return sbi->fault_info.inject_rate;
 }
+
+static int erofs_build_fault_attr(struct erofs_sb_info *sbi, substring_t *args)
+{
+       int rate = 0;
+
+       if (args->from && match_int(args, &rate))
+               return -EINVAL;
+
+       __erofs_build_fault_attr(sbi, rate);
+       return 0;
+}
 #else
+static void __erofs_build_fault_attr(struct erofs_sb_info *sbi,
+                                               unsigned int rate)
+{
+}
+
 static int erofs_build_fault_attr(struct erofs_sb_info *sbi,
                                        substring_t *args)
 {
@@ -644,10 +655,23 @@ static int erofs_show_options(struct seq_file *seq, 
struct dentry *root)
 
 static int erofs_remount(struct super_block *sb, int *flags, char *data)
 {
+       struct erofs_sb_info *sbi = EROFS_SB(sb);
+       unsigned int org_mnt_opt = sbi->mount_opt;
+       unsigned int org_inject_rate = erofs_get_fault_rate(sbi);
+       int err;
+
        BUG_ON(!sb_rdonly(sb));
+       err = parse_options(sb, data);
+       if (err)
+               goto out;
 
        *flags |= MS_RDONLY;
        return 0;
+out:
+       __erofs_build_fault_attr(sbi, org_inject_rate);
+       sbi->mount_opt = org_mnt_opt;
+
+       return err;
 }
 
 const struct super_operations erofs_sops = {
-- 
2.17.1

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