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Date:   Tue, 12 Jun 2018 13:07:01 -0600
From:   Andreas Dilger <adilger@...ger.ca>
To:     Wang Shilong <wangshilong1991@...il.com>
Cc:     Ext4 Developers List <linux-ext4@...r.kernel.org>,
        Shuichi Ihara <sihara@....com>, Wang Shilong <wshilong@....com>
Subject: Re: [PATCH 3/5] ext4: optimize to reduce redundant ext4_error()

On May 29, 2018, at 5:45 AM, Wang Shilong <wangshilong1991@...il.com> wrote:
> 
> From: Wang Shilong <wshilong@....com>
> 
> only call ext4_error() if new corrupted bit set,
> this could save us repeated error messages and
> unecessary super block write.
> 
> Suggested-by: Andreas Dilger <adilger@...ger.ca>
> Signed-off-by: Wang Shilong <wshilong@....com>

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

> ---
> fs/ext4/ext4.h  | 25 ++++++++++++++++---------
> fs/ext4/super.c | 14 ++++++++++----
> 2 files changed, 26 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index ed5b988..26f8c12 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -2530,9 +2530,9 @@ extern int ext4_alloc_flex_bg_array(struct super_block *sb,
> 				    ext4_group_t ngroup);
> extern const char *ext4_decode_error(struct super_block *sb, int errno,
> 				     char nbuf[16]);
> -extern void __ext4_mark_group_bitmap_corrupted(struct super_block *sb,
> -					       ext4_group_t block_group,
> -					       unsigned int flags);
> +extern int __ext4_mark_group_bitmap_corrupted(struct super_block *sb,
> +					      ext4_group_t block_group,
> +					      unsigned int flags);
> 
> extern __printf(4, 5)
> void __ext4_error(struct super_block *, const char *, unsigned int,
> @@ -2596,9 +2596,12 @@ void __ext4_grp_locked_error(const char *, unsigned int,
> 				flags, fmt, ##__VA_ARGS__)
> #define ext4_mark_group_bitmap_corrupted(sb, group, flags, fmt, ...)	\
> 	do {								\
> -		__ext4_error(sb, __func__, __LINE__,			\
> -			     fmt, ##__VA_ARGS__);			\
> -		__ext4_mark_group_bitmap_corrupted(sb, group, flags);	\
> +		int ret;						\
> +		ret = __ext4_mark_group_bitmap_corrupted(sb, group,	\
> +							flags);		\
> +		if (ret)						\
> +			__ext4_error(sb, __func__, __LINE__,		\
> +				     fmt, ##__VA_ARGS__);		\
> 	} while (0)
> 
> 
> @@ -2648,9 +2651,13 @@ void __ext4_grp_locked_error(const char *, unsigned int,
> } while (0)
> #define ext4_mark_group_bitmap_corrupted(sb, group, flags, fmt, ...)	\
> 	do {								\
> -		no_printk(fmt, ##__VA_ARGS__);				\
> -		__ext4_error(sb, "", 0, " ");				\
> -		__ext4_mark_group_bitmap_corrupted(sb, group, flags);	\
> +		int ret;						\
> +		ret = __ext4_mark_group_bitmap_corrupted(sb, group,	\
> +							 flags);	\
> +		if (ret) {						\
> +			no_printk(fmt, ##__VA_ARGS__);			\
> +			__ext4_error(sb, "", 0, " ");			\
> +		}							\
> 	} while (0)
> 
> #endif
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 554bceb..9f88991 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -766,21 +766,24 @@ void __ext4_grp_locked_error(const char *function, unsigned int line,
> 	return;
> }
> 
> -void __ext4_mark_group_bitmap_corrupted(struct super_block *sb,
> -					ext4_group_t group,
> -					unsigned int flags)
> +int __ext4_mark_group_bitmap_corrupted(struct super_block *sb,
> +				       ext4_group_t group,
> +				       unsigned int flags)
> {
> 	struct ext4_sb_info *sbi = EXT4_SB(sb);
> 	struct ext4_group_info *grp = ext4_get_group_info(sb, group);
> 	struct ext4_group_desc *gdp = ext4_get_group_desc(sb, group, NULL);
> 	int ret;
> +	int set = 0;
> 
> 	if (flags & EXT4_GROUP_INFO_BBITMAP_CORRUPT) {
> 		ret = ext4_test_and_set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT,
> 					    &grp->bb_state);
> -		if (!ret)
> +		if (!ret) {
> 			percpu_counter_sub(&sbi->s_freeclusters_counter,
> 					   grp->bb_free);
> +			set = 1;
> +		}
> 	}
> 
> 	if (flags & EXT4_GROUP_INFO_IBITMAP_CORRUPT) {
> @@ -792,8 +795,11 @@ void __ext4_mark_group_bitmap_corrupted(struct super_block *sb,
> 			count = ext4_free_inodes_count(sb, gdp);
> 			percpu_counter_sub(&sbi->s_freeinodes_counter,
> 					   count);
> +			set = 1;
> 		}
> 	}
> +
> +	return set;
> }
> 
> void ext4_update_dynamic_rev(struct super_block *sb)
> --
> 1.8.3.1
> 


Cheers, Andreas






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