On 10/18/23 16:26, André Draszik wrote: > On Wed, 2023-10-18 at 11:52 +0000, Bernd Schubert wrote: >> On 10/18/23 13:46, André Draszik wrote: >>> On Wed, 2023-10-18 at 11:39 +0000, Bernd Schubert wrote: >>>> On 10/18/23 13:15, André Draszik wrote: >>>>> From: André Draszik <andre.draszik@xxxxxxxxxx> >>>>> >>>>> This reverts commit 3066ff93476c35679cb07a97cce37d9bb07632ff. >>>>> >>>>> This patch breaks all existing userspace by requiring updates >>>>> as >>>>> mentioned in the commit message, which is not allowed. >>>>> >>>>> Revert to restore compatibility with existing userspace >>>>> implementations. >>>> >>>> Which fuse file system does it exactly break? In fact there >>>> haven't >>>> been >>>> added too many flags after - what exactly is broken? >>> >>> The original patch broke the existing kernel <-> user ABI by now >>> requiring user space applications to pass in an extra flag. >>> There are various side-effects of this, like unbootable systems, >>> just >>> because the kernel was updated. >>> Breaking the ABI is the one thing that is not allowed. This is not >>> specific to any particular fuse file system. >> >> How exactly did it break it? > > At least in Android, creating new files, or reading existing files > returns -EFAULT Hmm, could you please point me to the corresponding android userspace library? I guess it is not using libfuse? At least I would like to understand the issue... > >> These are feature flags - is there really a >> file system that relies on these flag to the extend that it does not >> work anymore? > > I don't know enough about the implementation details, but even outside > Android user space had to be updated as a prerequisite for this kernel > patch: > https://lore.kernel.org/all/YmUKZQKNAGimupv7@xxxxxxxxxx/ > https://github.com/libfuse/libfuse/pull/662 > > Which means any non-Android user space predating those changes isn't > working anymore either. The patch in libfuse is from me, there was nothing broken. And I don't think that any of the additional flags added are a _requirement_ for libfuse file systems to work. I'm not sure if DAX and the other flags before the patch was merged are a _requirement_ for virtiofsd or just a nice feature to have... In anyway, please still consider that using possibly uninitialized flags is not a good idea either and could randomly break things as well. Thanks, Bernd
