Re: git: b1de02c415de - main - vfs offset: fix assertion failure in face of racing ffofset and setfl locking

On Sun, Oct 05, 2025 at 09:22:01PM +0000, Mateusz Guzik wrote:
> The branch main has been updated by mjg:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=b1de02c415de5df2d24d8021827634fc095b7a26
> 
> commit b1de02c415de5df2d24d8021827634fc095b7a26
> Author:     Mateusz Guzik <mjg@FreeBSD.org>
> AuthorDate: 2025-10-05 17:03:54 +0000
> Commit:     Mateusz Guzik <mjg@FreeBSD.org>
> CommitDate: 2025-10-05 21:21:34 +0000
> 
>     vfs offset: fix assertion failure in face of racing ffofset and setfl locking
>     
>     Both use the same 16 bit var to store their locked and waiters bits,
>     then this in file_v_unlock:
>     
>             state = atomic_load_16(flagsp);
>             if ((state & lock_wait_bit) == 0 &&
>                 atomic_cmpset_rel_16(flagsp, state, state & ~lock_bit))
>                     return;
>     
>     can fail if for example foffset is being unlocked while setfl is getting
>     locked.
>     
>     Afterwards the code assumes there are blocked waiters on foffset.
>     
>     Reviewed by: kib, markj
>     Sponsored by:   Rubicon Communications, LLC ("Netgate")
>     Differential Revision: https://reviews.freebsd.org/D52915

This should be merged both to stable/15 and 14.