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 <exfat>/ mount -o remount,ro <exfat> the <exfat>/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 <hyc.lee@xxxxxxxxx> --- 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