From: Bernd Schubert <bschubert@xxxxxxx> commit 3ab394b363c5fd14b231e335fb6746ddfb93aaaa upstream. Current design and handling of passthrough is without fuse caching and with that FUSE_WRITEBACK_CACHE is conflicting. Fixes: 7dc4e97a4f9a ("fuse: introduce FUSE_PASSTHROUGH capability") Cc: stable@xxxxxxxxxx # v6.9 Signed-off-by: Bernd Schubert <bschubert@xxxxxxx> Acked-by: Amir Goldstein <amir73il@xxxxxxxxx> Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/fuse/inode.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -1336,11 +1336,16 @@ static void process_init_reply(struct fu * on a stacked fs (e.g. overlayfs) themselves and with * max_stack_depth == 1, FUSE fs can be stacked as the * underlying fs of a stacked fs (e.g. overlayfs). + * + * Also don't allow the combination of FUSE_PASSTHROUGH + * and FUSE_WRITEBACK_CACHE, current design doesn't handle + * them together. */ if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH) && (flags & FUSE_PASSTHROUGH) && arg->max_stack_depth > 0 && - arg->max_stack_depth <= FILESYSTEM_MAX_STACK_DEPTH) { + arg->max_stack_depth <= FILESYSTEM_MAX_STACK_DEPTH && + !(flags & FUSE_WRITEBACK_CACHE)) { fc->passthrough = 1; fc->max_stack_depth = arg->max_stack_depth; fm->sb->s_stack_depth = arg->max_stack_depth; Patches currently in stable-queue which might be from bschubert@xxxxxxx are queue-6.10/fuse-disable-the-combination-of-passthrough-and-writeback-cache.patch