linux-ext4 - Re: [PATCH] Ext4: tracepoint: fix broken print due to 0%o format

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Message-ID: <20180510163341.GF8335@thunk.org>
Date:   Thu, 10 May 2018 12:33:41 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Liu Bo <bo.liu@...ux.alibaba.com>
Cc:     linux-ext4@...r.kernel.org
Subject: Re: [PATCH] Ext4: tracepoint: fix broken print due to 0%o format

On Mon, Apr 30, 2018 at 01:04:26AM +0800, Liu Bo wrote:
> All the tracepoints in ext4 are printing i_mode with 0%o, and it ends up
> with
> 
> xfs_io-12320 [001] 10048.329506: ext4_da_reserve_space: dev 8,80 ino 17 mode 0>o< i_blocks 33152 reserved_data_blocks 0
> xfs_io-12320 [001] 10048.329610: ext4_da_update_reserve_space: dev 8,80 ino 17 mode 0>o< i_blocks 33152 used_blocks 0 reserved_data_blocks 2 quota_claim 2
> 
> '0%o' huas overridden the sibling field and shifted the output, note that
> the last @quota_claim should be 1 instead of 2.
> 
> This switches to print i_mode with 0x%x.

I'm not sure I understand the problem.  The tracecpoints are printing
octal correctly:

           <...>-396   [001] ...1  1569.646481: ext4_free_inode: dev 254,32 ino 12 mode 0100644 uid 0 gid 0 blocks 0

Permissions are traditionally printed in octal and "mode 0100644" is
doing the right thing here.

What tool are you using to print the tracing output?  I'm just using
"cat /sys/kernel/debug/tracing/trace_pipe".

					- Ted