linux-kernel - Re: [reiser4 SFRN 5.1.3] kernel [5.10.x] read not supported for file /test-exec \(pid: 10094 comm: debootstrap\)

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Message-ID: <12924b25-baa4-2965-65de-bc64ed43069f@gmail.com>
Date:   Sat, 14 Aug 2021 13:00:05 +0200
From:   Edward Shishkin <edward.shishkin@...il.com>
To:     Metztli Information Technology <jose.r.r@...ztli.com>
Cc:     reiserfs-devel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [reiser4 SFRN 5.1.3] kernel [5.10.x] read not supported for file
 /test-exec \(pid: 10094 comm: debootstrap\)

On 08/13/2021 05:20 PM, Metztli Information Technology wrote:

[...]

>>>
>>> Notwithstanding, I would appreciate if you can take a look at the
>>> attached patch. Probably it can be streamlined and/or improved
>>>    further to minimize pain on subsequent Linux kernel upgrades.
>>
>>
>> That patch is an attempt to swim against the current ;)
>>
>> I no longer remember, why they want to get rid of set_fs for already
>> 15
>> years, but ->read() and ->write() methods seem to be deprecated, and
>> the
>> correct way would be to implement the new ->read_iter() and
>> write_iter()
>> methods, where reiser4 works with "chunked" streams, represented by
>> iov_iter structure, rather than with "continuous" streams,
>> represented
>> by char __user *buf. The task is not that difficult, but rather time
>> consuming - I don't have a time for this right now..
> 
> On Sun, Jun 20, 2021 at 10:45 AM Edward Shishkin
> <edward.shishkin@...il.com> wrote:
>        So, I have implemented ->read_iter() for all plugins (*). It is
>        included
>        to reiser4-for-5.12 stuff. Not sure if it is enough to make distro with
>        root over reiser4 though: ->write_iter() is not yet implemented (not so
>        trivial because of transactions).
>        
>        (*)
>        https://github.com/edward6/reiser4/commit/ac72aba7e8bb16a28755c1b2b762971927d17c3c
>        
>        https://github.com/edward6/reiser4/commit/4d3200fbcb2003c680cdb822e3f616d3fa83c391
>        
>        Edward.
>        

Hello,

Now the new striped file plugin implements ->write_iter():
https://github.com/edward6/reiser4/commit/a3795ffffbb841bfaa66bfb18c12fb317533d1ff

[...]

> I finally got around to creating an SFRN 5.1.3 -enabled Debian
> Installer (d-i) for upcoming Debian 11 (codenamed Bullseye). Applied
> your unstable reiser4 for 5.12 patch onto my debianized hack packaging
> for Linux kernel 5.12.19 EOL.
> 
> I gave the d-i a spin in VirtualBox 6.1.26 and it choked on the
> following code fragment:
> ---------------------------------------------------------------------
> setup_dev_linux () {
>          # Ensure static device nodes created during install are
> preserved
>          # Tests in MAKEDEV require this is done in the D-I environment
>          mkdir -p /dev/.static/dev
>          chmod 700 /dev/.static/
>          mount --bind /target/dev /dev/.static/dev
>          # Mirror device nodes in D-I environment to target
>          mount --bind /dev /target/dev/
> }
> -----------------------------------------------------------------------
> 
> specifically:
> mount --bind /target/dev /dev/.static/dev
> 
> See relevant code fragment next to VirtualBox VM, where I manually
> entered the above directive:
> < https://metztli.it/bullseye-reiser5/d-i-sfrn5-fail.jpg >
> 
> i.e., '--bind' is causing the SFRN5 -enabled installer to bail out
> *only* for this reiser4 unstable SFRN 5.1.3 -patched kernel. On the
> other hand, as reported previously, no such issue occurs with your
> reiser4 stable SFRN 4.0.2 patch applied to the *same* debianized kernel
> source tree, Ed.

I have checked - everything works for me (Linux-5.12).

# mount /dev/vdd1 /mnt/test
# volume.reiser4 /mnt/test

Logical Volume Info:
ID:             03ac5995-bf77-4851-a302-e875a6fd752f
volume:         0x1 (asym)
distribution:   0x1 (fsx32m)
stripe:         262144
segments:       1024
bricks total:   3
bricks in DSA:  3
slots:          3
map blocks:     2
balanced:       Yes
health:         OK

# mkdir bindmnt
# mount --bind /mnt/test bindmnt
# mount
[...]
/dev/vdd1 on /mnt/test type reiser4 
(rw,relatime,atom_max_size=0x3d88e,atom_max_age=0x927c0,atom_min_size=0x100,atom_max_flushers=0x1,cbk_cache_slots=0x10)
/dev/vdd1 on /root/bindmnt type reiser4 
(rw,relatime,atom_max_size=0x3d88e,atom_max_age=0x927c0,atom_min_size=0x100,atom_max_flushers=0x1,cbk_cache_slots=0x10)

Thanks,
Edward.