[3/5] ext4: optimize to reduce redundant ext4_error()

Message ID 1527594317-9214-3-git-send-email-wshilong1991@gmail.com
State New
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Series
  • [1/5] ext4: fix race with setting free_inode/clusters_counter
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Commit Message

Wang Shilong May 29, 2018, 11:45 a.m.
From: Wang Shilong <wshilong@ddn.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@dilger.ca>
Signed-off-by: Wang Shilong <wshilong@ddn.com>
---
 fs/ext4/ext4.h  | 25 ++++++++++++++++---------
 fs/ext4/super.c | 14 ++++++++++----
 2 files changed, 26 insertions(+), 13 deletions(-)

Comments

Andreas Dilger June 4, 2018, 6:09 p.m. | #1
On May 29, 2018, at 5:45 AM, Wang Shilong <wangshilong1991@gmail.com> wrote:
> 
> From: Wang Shilong <wshilong@ddn.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@dilger.ca>
> Signed-off-by: Wang Shilong <wshilong@ddn.com>
> ---
> 
> 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,
> 
> -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;

Instead of adding a separate "set" variable, why not initialize "ret = 0"
and then return "!ret"?  It might be better to rename "ret" to something
more useful like "was_set" (which could be done in the original 1/5 patch).

Cheers, Andreas
Wang Shilong June 4, 2018, 11:41 p.m. | #2
Andreas,

> 
> On May 29, 2018, at 5:45 AM, Wang Shilong <wangshilong1991@gmail.com> wrote:
>> 
>> From: Wang Shilong <wshilong@ddn.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@dilger.ca>
>> Signed-off-by: Wang Shilong <wshilong@ddn.com>
>> ---
>> 
>> 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,
>> 
>> -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;
> 
> Instead of adding a separate "set" variable, why not initialize "ret = 0"
> and then return "!ret"?  It might be better to rename "ret" to something
> more useful like "was_set" (which could be done in the original 1/5 patch).
> 

This doesn’t work, because it is possible that we don’t set any bit for the flags passed in.
Or we could change it to:

If (flags & (EXT4_GROUP_INFO_IBITMAP_CORRUPT | EXT4_GROUP_INFO_BBITMAP_CORRUPT) && !ret)
       return 1;
else
      return 0;

Instead of something like this, introduced another bool value looks more readable?


> Cheers, Andreas
> 
> 
> 
> 
>
Andreas Dilger June 12, 2018, 7:07 p.m. | #3
On May 29, 2018, at 5:45 AM, Wang Shilong <wangshilong1991@gmail.com> wrote:
> 
> From: Wang Shilong <wshilong@ddn.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@dilger.ca>
> Signed-off-by: Wang Shilong <wshilong@ddn.com>

Reviewed-by: Andreas Dilger <adilger@dilger.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

Patch

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)