exfat: support modifying mount options via remount

Before this commit, all exfat-defined mount options could not be
modified dynamically via remount, and no error was returned.

After this commit, these three exfat-defined mount options
(discard, zero_size_dir, and errors) can be modified dynamically
via remount. While other exfat-defined mount options cannot be
modified dynamically via remount because their old settings are
cached in inodes or dentries, modifying them will be rejected with
an error.

Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index 8926e63f5bb7e12b602a9a8b1850f0b0a638c9d9..e1cffa46eb7370969d766c8cb36e95178f9e42f9 100644 (file)
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -243,11 +243,11 @@ static const struct fs_parameter_spec exfat_parameters[] = {
        fsparam_u32oct("allow_utime",           Opt_allow_utime),
        fsparam_string("iocharset",             Opt_charset),
        fsparam_enum("errors",                  Opt_errors, exfat_param_enums),
-       fsparam_flag("discard",                 Opt_discard),
+       fsparam_flag_no("discard",              Opt_discard),
        fsparam_flag("keep_last_dots",          Opt_keep_last_dots),
        fsparam_flag("sys_tz",                  Opt_sys_tz),
        fsparam_s32("time_offset",              Opt_time_offset),
-       fsparam_flag("zero_size_dir",           Opt_zero_size_dir),
+       fsparam_flag_no("zero_size_dir",        Opt_zero_size_dir),
        __fsparam(NULL, "utf8",                 Opt_utf8, fs_param_deprecated,
                  NULL),
        __fsparam(NULL, "debug",                Opt_debug, fs_param_deprecated,
@@ -299,7 +299,7 @@ static int exfat_parse_param(struct fs_context *fc, struct fs_parameter *param)
                opts->errors = result.uint_32;
                break;
        case Opt_discard:
-               opts->discard = 1;
+               opts->discard = !result.negated;
                break;
        case Opt_keep_last_dots:
                opts->keep_last_dots = 1;
@@ -317,7 +317,7 @@ static int exfat_parse_param(struct fs_context *fc, struct fs_parameter *param)
                opts->time_offset = result.int_32;
                break;
        case Opt_zero_size_dir:
-               opts->zero_size_dir = true;
+               opts->zero_size_dir = !result.negated;
                break;
        case Opt_utf8:
        case Opt_debug:
@@ -742,12 +742,44 @@ static void exfat_free(struct fs_context *fc)
 static int exfat_reconfigure(struct fs_context *fc)
 {
        struct super_block *sb = fc->root->d_sb;
+       struct exfat_sb_info *remount_sbi = fc->s_fs_info;
+       struct exfat_sb_info *sbi = EXFAT_SB(sb);
+       struct exfat_mount_options *new_opts = &remount_sbi->options;
+       struct exfat_mount_options *cur_opts = &sbi->options;
+
        fc->sb_flags |= SB_NODIRATIME;
 
        sync_filesystem(sb);
-       mutex_lock(&EXFAT_SB(sb)->s_lock);
+       mutex_lock(&sbi->s_lock);
        exfat_clear_volume_dirty(sb);
-       mutex_unlock(&EXFAT_SB(sb)->s_lock);
+       mutex_unlock(&sbi->s_lock);
+
+       if (new_opts->allow_utime == (unsigned short)-1)
+               new_opts->allow_utime = ~new_opts->fs_dmask & 0022;
+
+       /*
+        * Since the old settings of these mount options are cached in
+        * inodes or dentries, they cannot be modified dynamically.
+        */
+       if (strcmp(new_opts->iocharset, cur_opts->iocharset) ||
+           new_opts->keep_last_dots != cur_opts->keep_last_dots ||
+           new_opts->sys_tz != cur_opts->sys_tz ||
+           new_opts->time_offset != cur_opts->time_offset ||
+           !uid_eq(new_opts->fs_uid, cur_opts->fs_uid) ||
+           !gid_eq(new_opts->fs_gid, cur_opts->fs_gid) ||
+           new_opts->fs_fmask != cur_opts->fs_fmask ||
+           new_opts->fs_dmask != cur_opts->fs_dmask ||
+           new_opts->allow_utime != cur_opts->allow_utime)
+               return -EINVAL;
+
+       if (new_opts->discard != cur_opts->discard &&
+           new_opts->discard &&
+           !bdev_max_discard_sectors(sb->s_bdev)) {
+               exfat_warn(sb, "remounting with \"discard\" option, but the device does not support discard");
+               return -EINVAL;
+       }
+
+       swap(*cur_opts, *new_opts);
 
        return 0;
 }