linux-ext4 - Re: [PATCH v3 3/3] ext4: do not update s_last

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Message-ID: <20180514025707.GL14763@thunk.org>
Date:   Sun, 13 May 2018 22:57:07 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Amir Goldstein <amir73il@...il.com>
Cc:     Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org
Subject: Re: [PATCH v3 3/3] ext4: do not update s_last_mounted of a frozen fs

On Mon, Apr 23, 2018 at 09:00:08AM -0600, Amir Goldstein wrote:
> If fs is frozen after mount and before the first file open, the
> update of s_last_mounted bypasses freeze protection and prints out
> a WARNING splat:
> 
> $ mount /vdf
> $ fsfreeze -f /vdf
> $ cat /vdf/foo
> 
> [   31.578555] WARNING: CPU: 1 PID: 1415 at
> fs/ext4/ext4_jbd2.c:53 ext4_journal_check_start+0x48/0x82
> 
> [   31.614016] Call Trace:
> [   31.614997]  __ext4_journal_start_sb+0xe4/0x1a4
> [   31.616771]  ? ext4_file_open+0xb6/0x189
> [   31.618094]  ext4_file_open+0xb6/0x189
> 
> If fs is frozen, skip s_last_mounted update.
> 
> [backport hint: to apply to stable tree, need to apply also patches
>  vfs: add the sb_start_intwrite_trylock() helper
>  ext4: factor out helper ext4_sample_last_mounted()]
> 
> Fixes: bc0b0d6d69ee ("ext4: update the s_last_mounted field in the
> superblock")
> Cc: <stable@...r.kernel.org>
> Reviewed-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Amir Goldstein <amir73il@...il.com>

Applied, thanks.

					- Ted