> We need to commit dirty metadata and pages to disk before remounting exfat
> as read-only.
>
> This fixes a failure in xfstests generic/452
>
> generic/452 does the following:
> cp something /
> mount -o remount,ro
>
> the /something is corrupted. because while exfat is remounted as
> read-only, exfat doesn't have a chance to commit metadata and vfs
> invalidates page caches in a block device.
>
> Signed-off-by: Hyunchul Lee
Acked-by: Sungjong Seo
> ---
> Changes from v1:
> - Does not check the return value of sync_filesystem to
> allow to change from "rw" to "ro" even when this function
> fails.
> - Add the detailed explanation why generic/452 fails
>
> fs/exfat/super.c | 10 ++
> 1 file changed, 10 insertions(+)
>
> diff --git a/fs/exfat/super.c b/fs/exfat/super.c index
> e650e65536f8..253a92460d52 100644
> --- a/fs/exfat/super.c
> +++ b/fs/exfat/super.c
> @@ -693,10 +693,20 @@ static void exfat_free(struct fs_context *fc)
> }
> }
>
> +static int exfat_reconfigure(struct fs_context *fc) {
> + fc->sb_flags |= SB_NODIRATIME;
> +
> + /* volume flag will be updated in exfat_sync_fs */
> + sync_filesystem(fc->root->d_sb);
> + return 0;
> +}
> +
> static const struct fs_context_operations exfat_context_ops = {
> .parse_param= exfat_parse_param,
> .get_tree = exfat_get_tree,
> .free = exfat_free,
> + .reconfigure= exfat_reconfigure,
> };
>
> static int exfat_init_fs_context(struct fs_context *fc)
> --
> 2.17.1
