Re: [REGRESSION 6.1.70] system calls with CIFS mounts failing with "Resource temporarily unavailable"

[Salvatore Bonaccorso <carnil@debian.org>]

Hi Paulo, hi Greg,

On Tue, Jan 30, 2024 at 11:43:52PM +0100, Salvatore Bonaccorso wrote:
> Hi Paulo, hi Greg,
> 
> Note this is about the 5.10.y backports of the cifs issue, were system
> calls fail with "Resource temporarily unavailable".
> 
> On Mon, Jan 08, 2024 at 12:58:49PM -0300, Paulo Alcantara wrote:
> > Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes:
> > 
> > > Why can't we just include eb3e28c1e89b ("smb3: Replace smb2pdu 1-element
> > > arrays with flex-arrays") to resolve this?
> > 
> > Yep, this is the right way to go.
> > 
> > > I've queued it up now.
> > 
> > Thanks!
> 
> Is the underlying issue by picking the three commits:
> 
> 3080ea5553cc ("stddef: Introduce DECLARE_FLEX_ARRAY() helper")
> eb3e28c1e89b ("smb3: Replace smb2pdu 1-element arrays with flex-arrays")
> 
> and the last commit in linux-stable-rc for 5.10.y:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit?id=a280ecca48beb40ca6c0fc20dd5a7fdd9b3ee0b7
> 
> really fixing the issue?
> 
> Since we need to release a new update in Debian, I picked those three
> for testing on top of the 5.10.209-1 and while testing explicitly a
> cifs mount, I still get:
> 
> statfs(".", 0x7ffd809d5a70)             = -1 EAGAIN (Resource temporarily unavailable)
> 
> The same happens if I build
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit?id=a280ecca48beb40ca6c0fc20dd5a7fdd9b3ee0b7
> (knowing that it is not yet ready for review).
> 
> I'm slight confused as a280ecca48be ("cifs: fix off-by-one in
> SMB2_query_info_init()") says in the commit message:
> 
> [...]
> 	v5.10.y doesn't have
> 
>         eb3e28c1e89b ("smb3: Replace smb2pdu 1-element arrays with flex-arrays")
> 
> 	and the commit does
> [...]
> 
> and in meanwhile though the eb3e28c1e89b was picked (in a backported
> version). As 6.1.75-rc2 itself does not show the same problem, might
> there be a prerequisite missing in the backports for 5.10.y or a
> backport being wrong?

The problem seems to be that we are picking the backport for
eb3e28c1e89b, but then still applying 

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit?id=a280ecca48beb40ca6c0fc20dd5

which was made for the case in 5.10.y where eb3e28c1e89b is not
present.

I reverted a280ecca48beb40ca6c0fc20dd5 and now:

statfs(".", {f_type=SMB2_MAGIC_NUMBER, f_bsize=4096, f_blocks=2189197, f_bfree=593878, f_bavail=593878, f_files=0, f_ffree=0, f_fsid={val=[2004816114, 0]}, f_namelen=255, f_frsize=4096, f_flags=ST_VALID|ST_RELATIME}) = 0

Regards,
Salvatore