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Subject: Re: [PATCH v3] ext4: fix log printing of ext4_mb_regular_allocator()
To:     brookxu <brookxu.cn@gmail.com>, adilger.kernel@dilger.ca,
        tytso@mit.edu, linux-ext4@vger.kernel.org
References: <0a165ac0-1912-aebd-8a0d-b42e7cd1aea1@gmail.com>
From:   Ritesh Harjani <riteshh@linux.ibm.com>
Date:   Sun, 16 Aug 2020 10:55:48 +0530
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On 8/15/20 5:40 AM, brookxu wrote:
> Fix log printing of ext4_mb_regular_allocator()，it may be an
> unintentional behavior.
> 
> V3:
> It may be better to add a comma between start and len, which is
> convenient for script processing.
> 
> V2:
> Add more valuable information, such as group, start, len, lost.
> 
> Signed-off-by: Chunguang Xu <brookxu@tencent.com>

LGTM, please feel free to add:
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>

> ---
>   fs/ext4/mballoc.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index c0a331e..70b110f 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -2218,6 +2218,7 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
>   	struct ext4_sb_info *sbi;
>   	struct super_block *sb;
>   	struct ext4_buddy e4b;
> +	unsigned int lost;
>   
>   	sb = ac->ac_sb;
>   	sbi = EXT4_SB(sb);
> @@ -2341,22 +2342,24 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
>   		 * We've been searching too long. Let's try to allocate
>   		 * the best chunk we've found so far
>   		 */
> -
>   		ext4_mb_try_best_found(ac, &e4b);
>   		if (ac->ac_status != AC_STATUS_FOUND) {
>   			/*
>   			 * Someone more lucky has already allocated it.
>   			 * The only thing we can do is just take first
>   			 * found block(s)
> -			printk(KERN_DEBUG "EXT4-fs: someone won our chunk\n");
>   			 */
> +			lost = (unsigned int)atomic_inc_return(&sbi->s_mb_lost_chunks);
> +			mb_debug(sb, "lost chunk, group: %u, start: %d, len: %d, lost: %u\n",
> +				 ac->ac_b_ex.fe_group, ac->ac_b_ex.fe_start,
> +				 ac->ac_b_ex.fe_len, lost);
> +
>   			ac->ac_b_ex.fe_group = 0;
>   			ac->ac_b_ex.fe_start = 0;
>   			ac->ac_b_ex.fe_len = 0;
>   			ac->ac_status = AC_STATUS_CONTINUE;
>   			ac->ac_flags |= EXT4_MB_HINT_FIRST;
>   			cr = 3;
> -			atomic_inc(&sbi->s_mb_lost_chunks);
>   			goto repeat;
>   		}
>   	}
>