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Date: Fri, 5 Sep 2025 03:14:43 +0300
From: Konstantin Belousov <kostikbel@gmail.com>
To: obiwac <obiwac@freebsd.org>
Cc: freebsd-current@freebsd.org, freebsd-fs@freebsd.org,
        alan.somers@freebsd.org
Subject: Re: Fuse issue with attr caching expecting write lock
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On Fri, Sep 05, 2025 at 01:36:39AM +0200, obiwac wrote:
> Hi!
> 
> When trying to access a large file with sshfs (on fuse), I get a
> kernel panic because fuse_internal_cache_attrs is asserting a write
> lock when it is sometimes being called from fuse_internal_do_getattr,
> which only asserts a read lock.
> 
> To me (i.e. someone who has never touched VFS or fuse code) this code
> looks wrong, and fuse_internal_do_getattr should be acquiring a write
> lock around its call to fuse_internal_cache_attrs, but clearly it has
> been working just fine for a while now as this code hasn't changed
> super recently so I could be missing something.
It is only the assertions that were enabled recently.

Mark merged DEBUG_VFS_LOCKS option into INVARIANTS.