linux-kernel - Re: [PATCH 2/6] ext4: use 64-bit timestamps for mmp

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Message-Id: <711B183B-8F48-49C0-AC33-907384D10672@dilger.ca>
Date:   Thu, 21 Jun 2018 11:20:24 -0600
From:   Andreas Dilger <adilger@...ger.ca>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Theodore Ts'o <tytso@....edu>, Jan Kara <jack@...e.com>,
        y2038@...ts.linaro.org,
        Ext4 Developers List <linux-ext4@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/6] ext4: use 64-bit timestamps for mmp_time

On Jun 20, 2018, at 9:32 AM, Arnd Bergmann <arnd@...db.de> wrote:
> 
> The mmp_time field is 64 bits wide, which is good, but calling
> get_seconds() results in a 32-bit value on 32-bit architectures. Using
> ktime_get_real_seconds() instead returns 64 bits everywhere.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Reviewed-by: Andreas Dilger <adilger@...ger.ca>

> ---
> fs/ext4/mmp.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
> index 27b9a76a0dfa..39da4eb48361 100644
> --- a/fs/ext4/mmp.c
> +++ b/fs/ext4/mmp.c
> @@ -147,7 +147,7 @@ static int kmmpd(void *data)
> 
> 	mmp_block = le64_to_cpu(es->s_mmp_block);
> 	mmp = (struct mmp_struct *)(bh->b_data);
> -	mmp->mmp_time = cpu_to_le64(get_seconds());
> +	mmp->mmp_time = cpu_to_le64(ktime_get_real_seconds());
> 	/*
> 	 * Start with the higher mmp_check_interval and reduce it if
> 	 * the MMP block is being updated on time.
> @@ -165,7 +165,7 @@ static int kmmpd(void *data)
> 			seq = 1;
> 
> 		mmp->mmp_seq = cpu_to_le32(seq);
> -		mmp->mmp_time = cpu_to_le64(get_seconds());
> +		mmp->mmp_time = cpu_to_le64(ktime_get_real_seconds());
> 		last_update_time = jiffies;
> 
> 		retval = write_mmp_block(sb, bh);
> @@ -244,7 +244,7 @@ static int kmmpd(void *data)
> 	 * Unmount seems to be clean.
> 	 */
> 	mmp->mmp_seq = cpu_to_le32(EXT4_MMP_SEQ_CLEAN);
> -	mmp->mmp_time = cpu_to_le64(get_seconds());
> +	mmp->mmp_time = cpu_to_le64(ktime_get_real_seconds());
> 
> 	retval = write_mmp_block(sb, bh);
> 
> --
> 2.9.0
> 


Cheers, Andreas






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