linux-kernel - Re: [PATCH] f2fs: merge f2fs_show_injection_info() into time_to

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Date:   Sat, 17 Dec 2022 09:14:16 +0800
From:   Chao Yu <chao@...nel.org>
To:     Yangtao Li <frank.li@...o.com>, jaegeuk@...nel.org
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs: merge f2fs_show_injection_info() into
 time_to_inject()

On 2022/12/17 3:32, Yangtao Li wrote:
> Hi Chao,
> 
>> After moving f2fs_show_injection_info() core functionality into time_to_inject(),
>> __builtin_return_address(0) result changes from return address of caller of
>> f2fs_show_injection_info() to return address of time_to_inject().
> 
> It seems you are wrong, and the original patch didn't change the logic here.
> Because time_to_inject is an inline function, __builtin_return_address(0)
> has not return address of time_to_inject().

Yeah, but it depends on compile option, right? If user use -O0 or -fno-inline
option, inline function will not be expanded...

How about using deterministic implementation?

Thanks,

> 
> My test:
> 
> (1). w/ below patch, we found that the value of __builtin_return_address(0) in
> 	__time_to_inject() is the same as that in f2fs_show_injection_info().
> 
> # mount -t f2fs -o fault_type=0xffff,fault_injection=1 /mnt/9p/f2fs.img /mnt/f2fs
> [   19.739661] loop0: detected capacity change from 0 to 2097152
> [   19.749759]  new F2FS-fs (loop0) : inject kmalloc in f2fs_kmalloc of f2fs_fill_super+0x7eb/0x1780
> [   19.750313] raw F2FS-fs (loop0) : inject kmalloc in f2fs_kmalloc of f2fs_fill_super+0x7eb/0x1780
> mount: mounting /dev/loop0 on /mnt/f2fs failed: Cannot allocate memory
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 4035dab1f570..1e5030633f4d 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1876,11 +1876,13 @@ struct f2fs_sb_info {
> 
>   #ifdef CONFIG_F2FS_FAULT_INJECTION
>   #define f2fs_show_injection_info(sbi, type)                                    \
> -       printk_ratelimited("%sF2FS-fs (%s) : inject %s in %s of %pS\n", \
> +       printk_ratelimited("%sraw F2FS-fs (%s) : inject %s in %s of %pS\n",     \
>                  KERN_INFO, sbi->sb->s_id,                               \
>                  f2fs_fault_name[type],                                  \
>                  __func__, __builtin_return_address(0))
> -static inline bool time_to_inject(struct f2fs_sb_info *sbi, int type)
> +
> +#define time_to_inject(sbi, type) __time_to_inject(sbi, type, __func__)
> +static inline bool __time_to_inject(struct f2fs_sb_info *sbi, int type, const char *func_name)
>   {
>          struct f2fs_fault_info *ffi = &F2FS_OPTION(sbi).fault_info;
> 
> @@ -1893,6 +1895,10 @@ static inline bool time_to_inject(struct f2fs_sb_info *sbi, int type)
>          atomic_inc(&ffi->inject_ops);
>          if (atomic_read(&ffi->inject_ops) >= ffi->inject_rate) {
>                  atomic_set(&ffi->inject_ops, 0);
> +               printk_ratelimited("%s new F2FS-fs (%s) : inject %s in %s of %pS\n",
> +                       KERN_INFO, sbi->sb->s_id,
> +                       f2fs_fault_name[type],
> +                       func_name, __builtin_return_address(0));
>                  return true;
>          }
>          return false;
> 
> (2). w/ below patch(remove inline form __time_to_inject()), we found that the value of
> 	__builtin_return_address(0) in __time_to_inject() is different from that in
> 	f2fs_show_injection_info().
> 
> # mount -t f2fs -o fault_type=0xffff,fault_injection=1 /mnt/9p/f2fs.img /mnt/f2fs
> [   81.019451] loop0: detected capacity change from 0 to 2097152
> [   81.031058]  new F2FS-fs (loop0) : inject kmalloc in f2fs_kmalloc of f2fs_init_write_merge_io+0x35/0x1c0
> [   81.031745] raw F2FS-fs (loop0) : inject kmalloc in f2fs_kmalloc of f2fs_fill_super+0x7eb/0x1710
> mount: mounting /dev/loop0 on /mnt/f2fs failed: Cannot allocate memory
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 4035dab1f570..f15001b5d73b 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1876,11 +1876,13 @@ struct f2fs_sb_info {
> 
>   #ifdef CONFIG_F2FS_FAULT_INJECTION
>   #define f2fs_show_injection_info(sbi, type)                                    \
> -       printk_ratelimited("%sF2FS-fs (%s) : inject %s in %s of %pS\n", \
> +       printk_ratelimited("%sraw F2FS-fs (%s) : inject %s in %s of %pS\n",     \
>                  KERN_INFO, sbi->sb->s_id,                               \
>                  f2fs_fault_name[type],                                  \
>                  __func__, __builtin_return_address(0))
> -static inline bool time_to_inject(struct f2fs_sb_info *sbi, int type)
> +
> +#define time_to_inject(sbi, type) __time_to_inject(sbi, type, __func__)
> +static bool __time_to_inject(struct f2fs_sb_info *sbi, int type, const char *func_name)
>   {
>          struct f2fs_fault_info *ffi = &F2FS_OPTION(sbi).fault_info;
> 
> @@ -1893,6 +1895,10 @@ static inline bool time_to_inject(struct f2fs_sb_info *sbi, int type)
>          atomic_inc(&ffi->inject_ops);
>          if (atomic_read(&ffi->inject_ops) >= ffi->inject_rate) {
>                  atomic_set(&ffi->inject_ops, 0);
> +               printk_ratelimited("%s new F2FS-fs (%s) : inject %s in %s of %pS\n",
> +                       KERN_INFO, sbi->sb->s_id,
> +                       f2fs_fault_name[type],
> +                       func_name, __builtin_return_address(0));
>                  return true;
>          }
>          return false;
> 
> Thx,
> Yangtao