Re: [PATCH v2 0/3] CONFIG_VFS_DEBUG at last

[Mateusz Guzik]

On Thu, Feb 6, 2025 at 6:03 PM Mateusz Guzik <mjguzik@xxxxxxxxx> wrote:
>
> This adds a super basic version just to get the mechanism going and
> adds sample usage.
>
> The macro set is incomplete (e.g., lack of locking macros) and
> dump_inode routine fails to dump any state yet, to be implemented(tm).
>
> I think despite the primitive state this is complete enough to start
> sprinkling warns as necessary.
>
> v2:
> - correct may_open
> - fixed up condition reporting:
> before:
> VFS_WARN_ON_INODE(__builtin_choose_expr((sizeof(int) ==
> sizeof(*(8 ? ((void *)((long)(__builtin_strlen(link)) * 0l)) : (int
> *)8))), __builtin_strlen(link), __fortify_strlen(link)) != linklen)
> failed for inode ff32f7c350c8aec8
> after:
> VFS_WARN_ON_INODE(strlen(link) != linklen) failed for inode ff2b81ddca13f338
>

welp, the BSD asserts fire when the condition is false, while Linux
when it is true, so the *text* is backwards. should:
VFS_WARN_ON_INODE(strlen(link) != linklen) encountered for inode
ff2b81ddca13f338

modulo this bit I think this is fine for now

> Mateusz Guzik (3):
>   vfs: add initial support for CONFIG_VFS_DEBUG
>   vfs: catch invalid modes in may_open()
>   vfs: use the new debug macros in inode_set_cached_link()
>
>  fs/namei.c               |  2 ++
>  include/linux/fs.h       | 16 +++----------
>  include/linux/vfsdebug.h | 49 ++++++++++++++++++++++++++++++++++++++++
>  lib/Kconfig.debug        |  9 ++++++++
>  4 files changed, 63 insertions(+), 13 deletions(-)
>  create mode 100644 include/linux/vfsdebug.h
>
> --
> 2.43.0
>


-- 
Mateusz Guzik <mjguzik gmail.com>