Ocfs2 devel - Mar 2020 - [PATCH v2 0/4] ocfs2: seq_file .next functions should increase position index

Looks good.
Jun, could you please help verify these changes and give your tested-by? 
Since I don't have ocfs2 cluster locally...

Thanks,
Joseph

On 2020/2/26 14:52, Vasily Averin wrote:
> v2: resend with improved patch description
> 
> In Aug 2018 NeilBrown noticed 
> commit 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code
and interface")
> "Some ->next functions do not increment *pos when they return
NULL...
> Note that such ->next functions are buggy and should be fixed. 
> A simple demonstration is
>    
> dd if=/proc/swaps bs=1000 skip=1
>     
> Choose any block size larger than the size of /proc/swaps.  This will
> always show the whole last line of /proc/swaps"
> 
> /proc/swaps output was fixed recently, however there are lot of other
> affected files and 4 of them are related to ocfs2.
> 
> Unfortunately I'm not familiar with ocfs2 and cannot verify the patches
locally.
> 
> Usually you can observe following related problems:
> - read after lseek beyond end of file, described above by NeilBrown
>  "dd if=<AFFECTED_FILE> bs=1000 skip=1" will incorrectly
generate whole last line
> 
> - read after lseek on into middle of last line will output expected rest of
>  last line but then repeat whole last line once again. 
> 
> - If .show() function generates multi-line output following bash script
will never finish.
> 
>  $ q=;while read -r r;do echo "$((++q)) $r";done <
AFFECTED_FILE
> 
> Link:
https://urldefense.com/v3/__https://bugzilla.kernel.org/show_bug.cgi?id=206283__;!!GqivPVa7Brio!MWBujxdP_p0jZT4u4PHj-NBdhW4f9I2yRxwrFk8cG8MMHecBByM6r53K0M3eU9W5Oe1rdQ$
> 
> Vasily Averin (4):
>   lockres_seq_next should increase position index
>   ocfs2_dlm_seq_next should increase position index
>   nst_seq_next should increase position index
>   sc_seq_next should increase position index
> 
>  fs/ocfs2/cluster/netdebug.c | 2 ++
>  fs/ocfs2/dlm/dlmdebug.c     | 1 +
>  fs/ocfs2/dlmglue.c          | 1 +
>  3 files changed, 4 insertions(+)
>

On 2020/2/26 16:32, Joseph Qi wrote:
> Looks good.
> Jun, could you please help verify these changes and give your tested-by? 
> Since I don't have ocfs2 cluster locally...
OK, Shan will help testing this patch and give a 'tested-by' later.

Jun