linux-kernel - Re: [PATCH 1/4] fsfreeze: wait in killable state in __sb_start

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Message-ID: <51972E7A.1080601@alice.it>
Date:	Sat, 18 May 2013 09:32:10 +0200
From:	Marco <firefox82@...ce.it>
To:	Linux FS Devel <linux-fsdevel@...r.kernel.org>
CC:	linux-kernel@...r.kernel.org, Jan Kara <jack@...e.cz>
Subject: Re: [PATCH 1/4] fsfreeze: wait in killable state in __sb_start_write

Any comments about these patches?

Marco

Il 04/05/2013 08:49, Marco Stornelli ha scritto:
> Added a new enum to decide if we want to sleep in uninterruptible or
> killable state or we want simply to return immediately.
>
> Signed-off-by: Marco Stornelli <marco.stornelli@...il.com>
> Reviewed-by: Jan Kara <jack@...e.cz>
> ---
>   fs/super.c         |   24 ++++++++++++++++++------
>   include/linux/fs.h |   19 +++++++++++++------
>   2 files changed, 31 insertions(+), 12 deletions(-)
>
> diff --git a/fs/super.c b/fs/super.c
> index 7465d43..6b70c7f 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -1190,14 +1190,25 @@ static void acquire_freeze_lock(struct super_block *sb, int level, bool trylock,
>    * This is an internal function, please use sb_start_{write,pagefault,intwrite}
>    * instead.
>    */
> -int __sb_start_write(struct super_block *sb, int level, bool wait)
> +int __sb_start_write(struct super_block *sb, int level, int wait)
>   {
> +	int ret = 0;
>   retry:
>   	if (unlikely(sb->s_writers.frozen >= level)) {
> -		if (!wait)
> -			return 0;
> -		wait_event(sb->s_writers.wait_unfrozen,
> -			   sb->s_writers.frozen < level);
> +		switch (wait) {
> +		case FREEZE_NOWAIT:
> +			return ret;
> +		case FREEZE_WAIT:
> +			wait_event(sb->s_writers.wait_unfrozen,
> +				   sb->s_writers.frozen < level);
> +			break;
> +		case FREEZE_WAIT_KILLABLE:
> +			ret = wait_event_killable(sb->s_writers.wait_unfrozen,
> +				   sb->s_writers.frozen < level);
> +			if (ret)
> +				return -EINTR;
> +			break;
> +		}
>   	}
>
>   #ifdef CONFIG_LOCKDEP
> @@ -1213,7 +1224,8 @@ retry:
>   		__sb_end_write(sb, level);
>   		goto retry;
>   	}
> -	return 1;
> +	ret = 1;
> +	return ret;
>   }
>   EXPORT_SYMBOL(__sb_start_write);
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index e8cd6b8..6d9bcef 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1220,6 +1220,13 @@ enum {
>
>   #define SB_FREEZE_LEVELS (SB_FREEZE_COMPLETE - 1)
>
> +/* Possible waiting modes */
> +enum {
> +	FREEZE_NOWAIT = 0,		/* no blocking call */
> +	FREEZE_WAIT	= 1,		/* wait in uninterruptible state */
> +	FREEZE_WAIT_KILLABLE = 2,	/* wait in killable state */
> +};
> +
>   struct sb_writers {
>   	/* Counters for counting writers at each level */
>   	struct percpu_counter	counter[SB_FREEZE_LEVELS];
> @@ -1335,7 +1342,7 @@ extern struct timespec current_fs_time(struct super_block *sb);
>    */
>
>   void __sb_end_write(struct super_block *sb, int level);
> -int __sb_start_write(struct super_block *sb, int level, bool wait);
> +int __sb_start_write(struct super_block *sb, int level, int wait);
>
>   /**
>    * sb_end_write - drop write access to a superblock
> @@ -1394,12 +1401,12 @@ static inline void sb_end_intwrite(struct super_block *sb)
>    */
>   static inline void sb_start_write(struct super_block *sb)
>   {
> -	__sb_start_write(sb, SB_FREEZE_WRITE, true);
> +	__sb_start_write(sb, SB_FREEZE_WRITE, FREEZE_WAIT);
>   }
>
>   static inline int sb_start_write_trylock(struct super_block *sb)
>   {
> -	return __sb_start_write(sb, SB_FREEZE_WRITE, false);
> +	return __sb_start_write(sb, SB_FREEZE_WRITE, FREEZE_NOWAIT);
>   }
>
>   /**
> @@ -1423,7 +1430,7 @@ static inline int sb_start_write_trylock(struct super_block *sb)
>    */
>   static inline void sb_start_pagefault(struct super_block *sb)
>   {
> -	__sb_start_write(sb, SB_FREEZE_PAGEFAULT, true);
> +	__sb_start_write(sb, SB_FREEZE_PAGEFAULT, FREEZE_WAIT);
>   }
>
>   /*
> @@ -1441,7 +1448,7 @@ static inline void sb_start_pagefault(struct super_block *sb)
>    */
>   static inline void sb_start_intwrite(struct super_block *sb)
>   {
> -	__sb_start_write(sb, SB_FREEZE_FS, true);
> +	__sb_start_write(sb, SB_FREEZE_FS, FREEZE_WAIT);
>   }
>
>
> @@ -2224,7 +2231,7 @@ static inline void file_start_write(struct file *file)
>   {
>   	if (!S_ISREG(file_inode(file)->i_mode))
>   		return;
> -	__sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);
> +	__sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, FREEZE_WAIT);
>   }
>
>   static inline void file_end_write(struct file *file)
>
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