[f2fs-dev] [PATCH v5 1/2] f2fs: introduce proc/fs/f2fs/<dev>/fsck_stack node

[f2fs-dev] [PATCH v5 1/2] f2fs: introduce proc/fs/f2fs/<dev>/fsck_stack node

[Yangtao Li]

SBI_NEED_FSCK is an indicator that fsck.f2fs needs to be triggered,
this flag is set in too many places. For some scenes that are not very
reproducible, adding stack information will help locate the problem.

Let's expose all fsck stack history in procfs.

Signed-off-by: Yangtao Li <frank.li@vivo.com>
---
v5:
-fix implicit declaration of function 'stack_trace_save'
 fs/f2fs/f2fs.h  | 34 +++++++++++++++++++++++++++++++++-
 fs/f2fs/sysfs.c | 26 ++++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 67faa43cc141..cbd06dea3c6a 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -24,6 +24,8 @@
 #include <linux/quotaops.h>
 #include <linux/part_stat.h>
 #include <crypto/hash.h>
+#include <linux/stackdepot.h>
+#include <linux/stacktrace.h>
 
 #include <linux/fscrypt.h>
 #include <linux/fsverity.h>
@@ -119,6 +121,8 @@ typedef u32 nid_t;
 
 #define COMPRESS_EXT_NUM		16
 
+#define FSCK_STACK_DEPTH 64
+
 struct f2fs_mount_info {
 	unsigned int opt;
 	int write_io_size_bits;		/* Write IO size bits */
@@ -1786,6 +1790,8 @@ struct f2fs_sb_info {
 	unsigned int compress_watermark;	/* cache page watermark */
 	atomic_t compress_page_hit;		/* cache hit count */
 #endif
+	depot_stack_handle_t *fsck_stack;
+	unsigned int fsck_count;
 };
 
 struct f2fs_private_dio {
@@ -1997,9 +2003,35 @@ static inline bool is_sbi_flag_set(struct f2fs_sb_info *sbi, unsigned int type)
 	return test_bit(type, &sbi->s_flag);
 }
 
-static inline void set_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type)
+static void set_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type)
 {
 	set_bit(type, &sbi->s_flag);
+
+	if (unlikely(type ==  SBI_NEED_FSCK)) {
+		unsigned long entries[FSCK_STACK_DEPTH];
+		depot_stack_handle_t stack, *new;
+		unsigned int nr_entries;
+		int i;
+
+		nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
+		nr_entries = filter_irq_stacks(entries, nr_entries);
+		stack = stack_depot_save(entries, nr_entries, GFP_KERNEL);
+		if (!stack)
+			return;
+
+		/* Try to find an existing entry for this backtrace */
+		for (i = 0; i < sbi->fsck_count; i++)
+			if (sbi->fsck_stack[i] == stack)
+				return;
+
+		new = krealloc(sbi->fsck_stack, (sbi->fsck_count + 1) *
+			       sizeof(*sbi->fsck_stack), GFP_KERNEL);
+		if (!new)
+			return;
+
+		sbi->fsck_stack = new;
+		sbi->fsck_stack[sbi->fsck_count++] = stack;
+	}
 }
 
 static inline void clear_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type)
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 0954761341d7..c134bbb99c7b 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -1171,6 +1171,29 @@ static int __maybe_unused iostat_info_seq_show(struct seq_file *seq,
 	return 0;
 }
 
+static int __maybe_unused fsck_stack_seq_show(struct seq_file *seq,
+						void *offset)
+{
+	struct super_block *sb = seq->private;
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	unsigned long *entries;
+	unsigned int nr_entries;
+	unsigned int i, j;
+
+	for (i = 0; i < sbi->fsck_count; i++) {
+		nr_entries = stack_depot_fetch(sbi->fsck_stack[i], &entries);
+		if (!entries)
+			return 0;
+
+		for (j = 0; j < nr_entries; j++)
+			seq_printf(seq, "%pS\n", (void *)entries[j]);
+
+		seq_putc(seq, '\n');
+	}
+
+	return 0;
+}
+
 static int __maybe_unused victim_bits_seq_show(struct seq_file *seq,
 						void *offset)
 {
@@ -1261,6 +1284,8 @@ int f2fs_register_sysfs(struct f2fs_sb_info *sbi)
 				iostat_info_seq_show, sb);
 		proc_create_single_data("victim_bits", S_IRUGO, sbi->s_proc,
 				victim_bits_seq_show, sb);
+		proc_create_single_data("fsck_stack", S_IRUGO, sbi->s_proc,
+				fsck_stack_seq_show, sb);
 	}
 	return 0;
 put_feature_list_kobj:
@@ -1282,6 +1307,7 @@ void f2fs_unregister_sysfs(struct f2fs_sb_info *sbi)
 		remove_proc_entry("segment_info", sbi->s_proc);
 		remove_proc_entry("segment_bits", sbi->s_proc);
 		remove_proc_entry("victim_bits", sbi->s_proc);
+		remove_proc_entry("fsck_stack", sbi->s_proc);
 		remove_proc_entry(sbi->sb->s_id, f2fs_proc_root);
 	}
 
-- 
2.32.0



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[f2fs-dev] [PATCH v5 2/2] f2fs: convert S_IRUGO to 0444

[Yangtao Li]

WARNING: Symbolic permissions 'S_IRUGO' are not preferred. Consider using octal permissions '0444'.
+               proc_create_single_data("fsck_stack", S_IRUGO, sbi->s_proc,

Signed-off-by: Yangtao Li <frank.li@vivo.com>
---
 fs/f2fs/debug.c |  2 +-
 fs/f2fs/sysfs.c | 10 +++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index 473ad04d1891..401e5e34edd6 100644
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -621,7 +621,7 @@ void __init f2fs_create_root_stats(void)
 #ifdef CONFIG_DEBUG_FS
 	f2fs_debugfs_root = debugfs_create_dir("f2fs", NULL);
 
-	debugfs_create_file("status", S_IRUGO, f2fs_debugfs_root, NULL,
+	debugfs_create_file("status", 0444, f2fs_debugfs_root, NULL,
 			    &stat_fops);
 #endif
 }
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index c134bbb99c7b..09bf8c4be2b1 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -1276,15 +1276,15 @@ int f2fs_register_sysfs(struct f2fs_sb_info *sbi)
 		sbi->s_proc = proc_mkdir(sb->s_id, f2fs_proc_root);
 
 	if (sbi->s_proc) {
-		proc_create_single_data("segment_info", S_IRUGO, sbi->s_proc,
+		proc_create_single_data("segment_info", 0444, sbi->s_proc,
 				segment_info_seq_show, sb);
-		proc_create_single_data("segment_bits", S_IRUGO, sbi->s_proc,
+		proc_create_single_data("segment_bits", 0444, sbi->s_proc,
 				segment_bits_seq_show, sb);
-		proc_create_single_data("iostat_info", S_IRUGO, sbi->s_proc,
+		proc_create_single_data("iostat_info", 0444, sbi->s_proc,
 				iostat_info_seq_show, sb);
-		proc_create_single_data("victim_bits", S_IRUGO, sbi->s_proc,
+		proc_create_single_data("victim_bits", 0444, sbi->s_proc,
 				victim_bits_seq_show, sb);
-		proc_create_single_data("fsck_stack", S_IRUGO, sbi->s_proc,
+		proc_create_single_data("fsck_stack", 0444, sbi->s_proc,
 				fsck_stack_seq_show, sb);
 	}
 	return 0;
-- 
2.32.0



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Re: [f2fs-dev] [PATCH v5 1/2] f2fs: introduce proc/fs/f2fs/<dev>/fsck_stack node

[Chao Yu]

On 2021/8/13 20:32, Yangtao Li wrote:
> SBI_NEED_FSCK is an indicator that fsck.f2fs needs to be triggered,
> this flag is set in too many places. For some scenes that are not very
> reproducible, adding stack information will help locate the problem.
> 
> Let's expose all fsck stack history in procfs.
> 
> Signed-off-by: Yangtao Li <frank.li@vivo.com>
> ---
> v5:
> -fix implicit declaration of function 'stack_trace_save'
>   fs/f2fs/f2fs.h  | 34 +++++++++++++++++++++++++++++++++-
>   fs/f2fs/sysfs.c | 26 ++++++++++++++++++++++++++
>   2 files changed, 59 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 67faa43cc141..cbd06dea3c6a 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -24,6 +24,8 @@
>   #include <linux/quotaops.h>
>   #include <linux/part_stat.h>
>   #include <crypto/hash.h>
> +#include <linux/stackdepot.h>
> +#include <linux/stacktrace.h>
>   
>   #include <linux/fscrypt.h>
>   #include <linux/fsverity.h>
> @@ -119,6 +121,8 @@ typedef u32 nid_t;
>   
>   #define COMPRESS_EXT_NUM		16
>   
> +#define FSCK_STACK_DEPTH 64
> +
>   struct f2fs_mount_info {
>   	unsigned int opt;
>   	int write_io_size_bits;		/* Write IO size bits */
> @@ -1786,6 +1790,8 @@ struct f2fs_sb_info {
>   	unsigned int compress_watermark;	/* cache page watermark */
>   	atomic_t compress_page_hit;		/* cache hit count */
>   #endif
> +	depot_stack_handle_t *fsck_stack;
> +	unsigned int fsck_count;
>   };
>   
>   struct f2fs_private_dio {
> @@ -1997,9 +2003,35 @@ static inline bool is_sbi_flag_set(struct f2fs_sb_info *sbi, unsigned int type)
>   	return test_bit(type, &sbi->s_flag);
>   }
>   
> -static inline void set_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type)
> +static void set_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type)
>   {
>   	set_bit(type, &sbi->s_flag);
> +
> +	if (unlikely(type ==  SBI_NEED_FSCK)) {

Hmm... I don't know what to say...

> +		unsigned long entries[FSCK_STACK_DEPTH];
> +		depot_stack_handle_t stack, *new;
> +		unsigned int nr_entries;
> +		int i;
> +
> +		nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
> +		nr_entries = filter_irq_stacks(entries, nr_entries);
> +		stack = stack_depot_save(entries, nr_entries, GFP_KERNEL);
> +		if (!stack)
> +			return;
> +
> +		/* Try to find an existing entry for this backtrace */
> +		for (i = 0; i < sbi->fsck_count; i++)
> +			if (sbi->fsck_stack[i] == stack)

stack need to be released here?

> +				return;
> +
> +		new = krealloc(sbi->fsck_stack, (sbi->fsck_count + 1) *
> +			       sizeof(*sbi->fsck_stack), GFP_KERNEL);
> +		if (!new)

Ditto?

> +			return;
> +
> +		sbi->fsck_stack = new;

Need to be released somewhere.

> +		sbi->fsck_stack[sbi->fsck_count++] = stack;

Need to be released somewhere.

> +	}
>   }
>   
>   static inline void clear_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type)
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 0954761341d7..c134bbb99c7b 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -1171,6 +1171,29 @@ static int __maybe_unused iostat_info_seq_show(struct seq_file *seq,
>   	return 0;
>   }
>   
> +static int __maybe_unused fsck_stack_seq_show(struct seq_file *seq,
> +						void *offset)
> +{
> +	struct super_block *sb = seq->private;
> +	struct f2fs_sb_info *sbi = F2FS_SB(sb);
> +	unsigned long *entries;
> +	unsigned int nr_entries;
> +	unsigned int i, j;
> +
> +	for (i = 0; i < sbi->fsck_count; i++) {
> +		nr_entries = stack_depot_fetch(sbi->fsck_stack[i], &entries);
> +		if (!entries)
> +			return 0;
> +
> +		for (j = 0; j < nr_entries; j++)
> +			seq_printf(seq, "%pS\n", (void *)entries[j]);
> +
> +		seq_putc(seq, '\n');
> +	}
> +
> +	return 0;
> +}
> +
>   static int __maybe_unused victim_bits_seq_show(struct seq_file *seq,
>   						void *offset)
>   {
> @@ -1261,6 +1284,8 @@ int f2fs_register_sysfs(struct f2fs_sb_info *sbi)
>   				iostat_info_seq_show, sb);
>   		proc_create_single_data("victim_bits", S_IRUGO, sbi->s_proc,
>   				victim_bits_seq_show, sb);
> +		proc_create_single_data("fsck_stack", S_IRUGO, sbi->s_proc,
> +				fsck_stack_seq_show, sb);
>   	}
>   	return 0;
>   put_feature_list_kobj:
> @@ -1282,6 +1307,7 @@ void f2fs_unregister_sysfs(struct f2fs_sb_info *sbi)
>   		remove_proc_entry("segment_info", sbi->s_proc);
>   		remove_proc_entry("segment_bits", sbi->s_proc);
>   		remove_proc_entry("victim_bits", sbi->s_proc);
> +		remove_proc_entry("fsck_stack", sbi->s_proc);
>   		remove_proc_entry(sbi->sb->s_id, f2fs_proc_root);
>   	}
>   
> 


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Re: [f2fs-dev] [PATCH v5 1/2] f2fs: introduce proc/fs/f2fs/<dev>/fsck_stack node

[李扬韬]

From: Chao Yu <chao@kernel.org>
Date: 2021-08-13 22:44:49
To:  Yangtao Li <frank.li@vivo.com>,jaegeuk@kernel.org
Cc:  linux-f2fs-devel@lists.sourceforge.net,linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 1/2] f2fs: introduce proc/fs/f2fs/<dev>/fsck_stack node>On 2021/8/13 20:32, Yangtao Li wrote:
>> SBI_NEED_FSCK is an indicator that fsck.f2fs needs to be triggered,
>> this flag is set in too many places. For some scenes that are not very
>> reproducible, adding stack information will help locate the problem.
>> 
>> Let's expose all fsck stack history in procfs.
>> 
>> Signed-off-by: Yangtao Li <frank.li@vivo.com>
>> ---
>> v5:
>> -fix implicit declaration of function 'stack_trace_save'
>>   fs/f2fs/f2fs.h  | 34 +++++++++++++++++++++++++++++++++-
>>   fs/f2fs/sysfs.c | 26 ++++++++++++++++++++++++++
>>   2 files changed, 59 insertions(+), 1 deletion(-)
>> 
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 67faa43cc141..cbd06dea3c6a 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -24,6 +24,8 @@
>>   #include <linux/quotaops.h>
>>   #include <linux/part_stat.h>
>>   #include <crypto/hash.h>
>> +#include <linux/stackdepot.h>
>> +#include <linux/stacktrace.h>
>>   
>>   #include <linux/fscrypt.h>
>>   #include <linux/fsverity.h>
>> @@ -119,6 +121,8 @@ typedef u32 nid_t;
>>   
>>   #define COMPRESS_EXT_NUM		16
>>   
>> +#define FSCK_STACK_DEPTH 64
>> +
>>   struct f2fs_mount_info {
>>   	unsigned int opt;
>>   	int write_io_size_bits;		/* Write IO size bits */
>> @@ -1786,6 +1790,8 @@ struct f2fs_sb_info {
>>   	unsigned int compress_watermark;	/* cache page watermark */
>>   	atomic_t compress_page_hit;		/* cache hit count */
>>   #endif
>> +	depot_stack_handle_t *fsck_stack;
>> +	unsigned int fsck_count;
>>   };
>>   
>>   struct f2fs_private_dio {
>> @@ -1997,9 +2003,35 @@ static inline bool is_sbi_flag_set(struct f2fs_sb_info *sbi, unsigned int type)
>>   	return test_bit(type, &sbi->s_flag);
>>   }
>>   
>> -static inline void set_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type)
>> +static void set_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type)
>>   {
>>   	set_bit(type, &sbi->s_flag);
>> +
>> +	if (unlikely(type ==  SBI_NEED_FSCK)) {
>
>Hmm... I don't know what to say...

Sorry, maybe there is a problem with my vim configuration.
The strange thing is that checkpatch.pl didn't check it out.

>
>> +		unsigned long entries[FSCK_STACK_DEPTH];
>> +		depot_stack_handle_t stack, *new;
>> +		unsigned int nr_entries;
>> +		int i;
>> +
>> +		nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
>> +		nr_entries = filter_irq_stacks(entries, nr_entries);
>> +		stack = stack_depot_save(entries, nr_entries, GFP_KERNEL);
>> +		if (!stack)
>> +			return;
>> +
>> +		/* Try to find an existing entry for this backtrace */
>> +		for (i = 0; i < sbi->fsck_count; i++)
>> +			if (sbi->fsck_stack[i] == stack)
>
>stack need to be released here?

We can't remove stack from depot, as we store them contiguously one after
another in a contiguous memory allocation.

Or we can limit the recorded stack number.

$ grep -nr "SBI_NEED_FSCK" fs/f2fs/ --include=*.c --include=*.h | wc -l
53
$ grep -nr "f2fs_bug_on" fs/f2fs/ --include=*.c --include=*.h | wc -l
135

Since we only have two hundred possible settings here, considering that
the same stack will not be recorded, and the probability of occurrence will
not be high, so it is acceptable not to release?

If this is the case, the subsequent allocation does not need to be released.

Thx,
Yangtao


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Re: [f2fs-dev] [PATCH v5 1/2] f2fs: introduce proc/fs/f2fs/<dev>/fsck_stack node

[Chao Yu]

On 2021/8/14 2:33, 李扬韬 wrote:
> From: Chao Yu <chao@kernel.org>
> Date: 2021-08-13 22:44:49
> To:  Yangtao Li <frank.li@vivo.com>,jaegeuk@kernel.org
> Cc:  linux-f2fs-devel@lists.sourceforge.net,linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v5 1/2] f2fs: introduce proc/fs/f2fs/<dev>/fsck_stack node>On 2021/8/13 20:32, Yangtao Li wrote:
>>> SBI_NEED_FSCK is an indicator that fsck.f2fs needs to be triggered,
>>> this flag is set in too many places. For some scenes that are not very
>>> reproducible, adding stack information will help locate the problem.
>>>
>>> Let's expose all fsck stack history in procfs.
>>>
>>> Signed-off-by: Yangtao Li <frank.li@vivo.com>
>>> ---
>>> v5:
>>> -fix implicit declaration of function 'stack_trace_save'
>>>    fs/f2fs/f2fs.h  | 34 +++++++++++++++++++++++++++++++++-
>>>    fs/f2fs/sysfs.c | 26 ++++++++++++++++++++++++++
>>>    2 files changed, 59 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>> index 67faa43cc141..cbd06dea3c6a 100644
>>> --- a/fs/f2fs/f2fs.h
>>> +++ b/fs/f2fs/f2fs.h
>>> @@ -24,6 +24,8 @@
>>>    #include <linux/quotaops.h>
>>>    #include <linux/part_stat.h>
>>>    #include <crypto/hash.h>
>>> +#include <linux/stackdepot.h>
>>> +#include <linux/stacktrace.h>
>>>    
>>>    #include <linux/fscrypt.h>
>>>    #include <linux/fsverity.h>
>>> @@ -119,6 +121,8 @@ typedef u32 nid_t;
>>>    
>>>    #define COMPRESS_EXT_NUM		16
>>>    
>>> +#define FSCK_STACK_DEPTH 64
>>> +
>>>    struct f2fs_mount_info {
>>>    	unsigned int opt;
>>>    	int write_io_size_bits;		/* Write IO size bits */
>>> @@ -1786,6 +1790,8 @@ struct f2fs_sb_info {
>>>    	unsigned int compress_watermark;	/* cache page watermark */
>>>    	atomic_t compress_page_hit;		/* cache hit count */
>>>    #endif
>>> +	depot_stack_handle_t *fsck_stack;
>>> +	unsigned int fsck_count;
>>>    };
>>>    
>>>    struct f2fs_private_dio {
>>> @@ -1997,9 +2003,35 @@ static inline bool is_sbi_flag_set(struct f2fs_sb_info *sbi, unsigned int type)
>>>    	return test_bit(type, &sbi->s_flag);
>>>    }
>>>    
>>> -static inline void set_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type)
>>> +static void set_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type)
>>>    {
>>>    	set_bit(type, &sbi->s_flag);
>>> +
>>> +	if (unlikely(type ==  SBI_NEED_FSCK)) {
>>
>> Hmm... I don't know what to say...
> 
> Sorry, maybe there is a problem with my vim configuration.
> The strange thing is that checkpatch.pl didn't check it out.
> 
>>
>>> +		unsigned long entries[FSCK_STACK_DEPTH];
>>> +		depot_stack_handle_t stack, *new;
>>> +		unsigned int nr_entries;
>>> +		int i;
>>> +
>>> +		nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
>>> +		nr_entries = filter_irq_stacks(entries, nr_entries);
>>> +		stack = stack_depot_save(entries, nr_entries, GFP_KERNEL);
>>> +		if (!stack)
>>> +			return;
>>> +
>>> +		/* Try to find an existing entry for this backtrace */
>>> +		for (i = 0; i < sbi->fsck_count; i++)
>>> +			if (sbi->fsck_stack[i] == stack)
>>
>> stack need to be released here?
> 
> We can't remove stack from depot, as we store them contiguously one after
> another in a contiguous memory allocation.
> 
> Or we can limit the recorded stack number.
> 
> $ grep -nr "SBI_NEED_FSCK" fs/f2fs/ --include=*.c --include=*.h | wc -l
> 53
> $ grep -nr "f2fs_bug_on" fs/f2fs/ --include=*.c --include=*.h | wc -l
> 135

I didn't look into details of stack_depot_save(), two stack handles from below
call paths will be the same?

- move_data_block
  - f2fs_wait_on_page_writeback
   - f2fs_bug_on

- ra_data_block
  - f2fs_wait_on_page_writeback
   - f2fs_bug_on

If they have different stack handles, combination number of
set_sbi_flag(NEED_FSCK)/f2fs_bug_on and their callers will be far more than two
hundred.

Thanks,

> 
> Since we only have two hundred possible settings here, considering that
> the same stack will not be recorded, and the probability of occurrence will
> not be high, so it is acceptable not to release?
> 
> If this is the case, the subsequent allocation does not need to be released.
> 
> Thx,
> Yangtao
> 


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Re: [f2fs-dev] [PATCH v5 1/2] f2fs: introduce proc/fs/f2fs/<dev>/fsck_stack node

[李扬韬]

>> We can't remove stack from depot, as we store them contiguously one after
>> another in a contiguous memory allocation.
>> 
>> Or we can limit the recorded stack number.
>> 
>> $ grep -nr "SBI_NEED_FSCK" fs/f2fs/ --include=*.c --include=*.h | wc -l
>> 53
>> $ grep -nr "f2fs_bug_on" fs/f2fs/ --include=*.c --include=*.h | wc -l
>> 135
>
>I didn't look into details of stack_depot_save(), two stack handles from below
>call paths will be the same?
>
>- move_data_block
>  - f2fs_wait_on_page_writeback
>   - f2fs_bug_on
>
>- ra_data_block
>  - f2fs_wait_on_page_writeback
>   - f2fs_bug_on
>
>If they have different stack handles, combination number of
>set_sbi_flag(NEED_FSCK)/f2fs_bug_on and their callers will be far more than two
>hundred.
>

Yes, these will be two different stacks. In the most extreme case, there will be 1000 (I guess) different places to set fsck?
Or we limit the number of recorded stacks to 10?
what do you think. The stack depot design does not consider removing the stack from the depot.

MBR,
Yangtao


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Re: [f2fs-dev] [PATCH v5 1/2] f2fs: introduce proc/fs/f2fs/<dev>/fsck_stack node

[Christoph Hellwig]

Please don't add new non-process files to procfs.


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Re: [f2fs-dev] [PATCH v5 1/2] f2fs: introduce proc/fs/f2fs/<dev>/fsck_stack node

[Chao Yu]

On 2021/8/14 10:08, 李扬韬 wrote:
>>> We can't remove stack from depot, as we store them contiguously one after
>>> another in a contiguous memory allocation.
>>>
>>> Or we can limit the recorded stack number.
>>>
>>> $ grep -nr "SBI_NEED_FSCK" fs/f2fs/ --include=*.c --include=*.h | wc -l
>>> 53
>>> $ grep -nr "f2fs_bug_on" fs/f2fs/ --include=*.c --include=*.h | wc -l
>>> 135
>>
>> I didn't look into details of stack_depot_save(), two stack handles from below
>> call paths will be the same?
>>
>> - move_data_block
>>   - f2fs_wait_on_page_writeback
>>    - f2fs_bug_on
>>
>> - ra_data_block
>>   - f2fs_wait_on_page_writeback
>>    - f2fs_bug_on
>>
>> If they have different stack handles, combination number of
>> set_sbi_flag(NEED_FSCK)/f2fs_bug_on and their callers will be far more than two
>> hundred.
>>
> 
> Yes, these will be two different stacks. In the most extreme case, there will be 1000 (I guess) different places to set fsck?

It may be according to call stack height of each handle record.

> Or we limit the number of recorded stacks to 10?

Yes, please limit the record number, maybe 8? and stack height could be 16 at
maximum?

Thanks,

> what do you think. The stack depot design does not consider removing the stack from the depot.
> 
> MBR,
> Yangtao
> 


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