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From: Dave Chinner <david@fromorbit.com>
To: Hou Tao <houtao1@huawei.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH] xfs_logprint: fix the transcation type string for delaylog-enabled fs
Date: Tue, 13 Sep 2016 17:09:13 +1000	[thread overview]
Message-ID: <20160913070913.GG30497@dastard> (raw)
In-Reply-To: <1473394107-3399-1-git-send-email-houtao1@huawei.com>

On Fri, Sep 09, 2016 at 12:08:27PM +0800, Hou Tao wrote:
> For delaylog-enabled fs, the only th_type is XFS_TRANS_CHECKPOINT,
> but the value of XFS_TRANS_CHECKPOINT had been change from 42 to 40
> by xfs commit 61e63ec (xfs: consolidate superblock logging functions),
> so return trans_type[type] directly will be incorrect.
> And there is no flag for delaylog testing, so the suboptimal solution
> is to use super v5 flag instead. For pre-v5 fs used by kernel after
> commit 61e63ec, the result of xlog_trans_type will still be incorrect.

delaylog and v5 superblocks are completely unrelated and so this is
incorrect.

> before patch:
> (1) v5 fs
> TRAN:    type: SWAPEXT       tid: 321be024       num_items: 2
> TRANS: tid:0x772d0805  type:SWAPEXT  #items:37  trans:0x772d0805  q:0x559104d71bc0
> 
> after patch:
> (2) v5 fs
> TRAN:    type: CHECKPOINT       tid: 321be024       num_items: 2
> TRANS: tid:0x772d0805  type:SWAPEXT  #items:37  trans:0x772d0805  q:0x559104d71bc0

And so v4 filesystems are still incorrect.

Indeed, when delaylog is enabled, the only transaction type in the
log is "CHECKPOINT" - the whole "trans type" stuff has gone away
from the kernel and only exists as this in xfs_log_format.h:

/*
 * The only type valid for th_type in CIL-enabled file system logs:
 */
#define XFS_TRANS_CHECKPOINT    40

IOWs, most of the logprint code is for printing log information from
pre-delaylog kernels. IOWs, for the anyone using a 3.0+ kernel, the
"trans type" output from xfs_logprint is completely useless
information, so we should probably either put it behind a command
line option or remove it completely...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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  reply	other threads:[~2016-09-13  7:09 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-09  4:08 [PATCH] xfs_logprint: fix the transcation type string for delaylog-enabled fs Hou Tao
2016-09-13  7:09 ` Dave Chinner [this message]
2016-09-14  1:02   ` Hou Tao
2016-09-14  5:31     ` Dave Chinner
2016-09-14 11:00       ` Hou Tao
2016-09-14 11:31       ` [PATCH] xfs_logprint: remove the printing of transaction type Hou Tao

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