Re: [PATCH v1 0/9] Support Clang context analysis for ext2

[Jan Kara]

On Sun 12-07-26 12:56:01, Timothy Day wrote:
> This series adds annotations for Clang's context analysis to ext2.
> Clang context analysis was recently added in a series by Marco
> Elver [1]. This allows the compiler to validate different
> locking patterns at compile time.
> 
> This series enables context analysis, fixes pre-existing warnings,
> and adds new annotations. It is inspired by similar series in the
> block layer (NVMe host driver, for example [2]).
> 
> I'm starting with ext2 since it's smaller and simpler compared to
> ext4/btrfs/etc. After ext2, I'd be interested in converting the
> other filesystems and infrastructure code in fs/. I think the ultimate
> goal would be to enable this by default across all of fs/.
> 
> The series was built and tested with Clang 23 with
> CONFIG_WARN_CONTEXT_ANALYSIS enabled. I based on 7.2-rc2 (since the
> minimum Clang version was recently bumped to 23 in 7.2+ [3]).
> 
> I'd appreciate reviews and suggestions. I'm especially interested in
> suggestions on how we can make this easier to enable for other
> filesystems.
> 
> Thanks!

Overall this looks sane to me and I kind of like the documentation value of
__guarded_by and __must_hold annotations. The context_unsafe annotations
are a bit annoying but I can live with that for now. Just one question: do
I understand right that the compiler verifies whether the lock is held when
entering the function marked with __must_hold? So if we get the annotation
wrong, the compiler will tell us?

								Honza

> 
> [1] https://lore.kernel.org/lkml/20251219154418.3592607-1-elver@xxxxxxxxxx/
> [2] https://lore.kernel.org/all/20260706141452.3008233-1-nilay@xxxxxxxxxxxxx/
> [3] https://lore.kernel.org/all/20260515124426.2227783-1-elver@xxxxxxxxxx/
> 
> Timothy Day (9):
>   ext2: fix ext2_xattr_delete_inode() context analysis warning
>   ext2: mark s_next_generation as guarded by s_next_gen_lock
>   ext2: annotate ext2_update_dynamic_rev() as requiring s_lock
>   ext2: mark statfs overhead cache as guarded by s_lock
>   ext2: mark s_mount_state as guarded by s_lock
>   ext2: annotate ext2_init_block_alloc_info() as requiring
>     truncate_mutex
>   ext2: annotate block-mapping helpers as requiring truncate_mutex
>   ext2: annotate s_rsv_window_root as requiring s_rsv_window_lock
>   ext2: enabled context analysis support for ext2 filesystem
> 
>  fs/ext2/Makefile |  2 ++
>  fs/ext2/balloc.c |  4 ++++
>  fs/ext2/ext2.h   | 19 +++++++++++--------
>  fs/ext2/inode.c  |  7 +++++++
>  fs/ext2/super.c  | 18 +++++++++++++-----
>  fs/ext2/xattr.c  |  4 +++-
>  6 files changed, 40 insertions(+), 14 deletions(-)
> 
> -- 
> 2.39.5
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR