linux-kernel - Re: [PATCH v2 1/8] introduce __sb_{acquire,release}

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Date:	Thu, 13 Aug 2015 11:45:52 +0200
From:	Jan Kara <jack@...e.cz>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Al Viro <viro@...iv.linux.org.uk>,
	Dave Chinner <david@...morbit.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Jan Kara <jack@...e.cz>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/8] introduce __sb_{acquire,release}_write() helpers

On Tue 11-08-15 19:03:58, Oleg Nesterov wrote:
> Preparation to hide the sb->s_writers internals from xfs and btrfs.
> Add 2 trivial define's they can use rather than play with ->s_writers
> directly. No changes in btrfs/transaction.o and xfs/xfs_aops.o.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@...e.com>

								Honza

> ---
>  fs/btrfs/transaction.c |    8 ++------
>  fs/xfs/xfs_aops.c      |    6 ++----
>  include/linux/fs.h     |    5 +++++
>  3 files changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> index 5628e25..6dca4e9 100644
> --- a/fs/btrfs/transaction.c
> +++ b/fs/btrfs/transaction.c
> @@ -1620,9 +1620,7 @@ static void do_async_commit(struct work_struct *work)
>  	 * Tell lockdep about it.
>  	 */
>  	if (ac->newtrans->type & __TRANS_FREEZABLE)
> -		rwsem_acquire_read(
> -		     &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
> -		     0, 1, _THIS_IP_);
> +		__sb_acquire_write(ac->root->fs_info->sb, SB_FREEZE_FS);
>  
>  	current->journal_info = ac->newtrans;
>  
> @@ -1661,9 +1659,7 @@ int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
>  	 * async commit thread will be the one to unlock it.
>  	 */
>  	if (ac->newtrans->type & __TRANS_FREEZABLE)
> -		rwsem_release(
> -			&root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
> -			1, _THIS_IP_);
> +		__sb_release_write(root->fs_info->sb, SB_FREEZE_FS);
>  
>  	schedule_work(&ac->work);
>  
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index a56960d..8034c78 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -119,8 +119,7 @@ xfs_setfilesize_trans_alloc(
>  	 * We may pass freeze protection with a transaction.  So tell lockdep
>  	 * we released it.
>  	 */
> -	rwsem_release(&ioend->io_inode->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
> -		      1, _THIS_IP_);
> +	__sb_release_write(ioend->io_inode->i_sb, SB_FREEZE_FS);
>  	/*
>  	 * We hand off the transaction to the completion thread now, so
>  	 * clear the flag here.
> @@ -171,8 +170,7 @@ xfs_setfilesize_ioend(
>  	 * Similarly for freeze protection.
>  	 */
>  	current_set_flags_nested(&tp->t_pflags, PF_FSTRANS);
> -	rwsem_acquire_read(&VFS_I(ip)->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
> -			   0, 1, _THIS_IP_);
> +	__sb_acquire_write(VFS_I(ip)->i_sb, SB_FREEZE_FS);
>  
>  	return xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size);
>  }
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 35ec87e..78ac768 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1362,6 +1362,11 @@ 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);
>  
> +#define __sb_acquire_write(sb, lev)	\
> +	rwsem_acquire_read(&(sb)->s_writers.lock_map[(lev)-1], 0, 1, _THIS_IP_)
> +#define __sb_release_write(sb, lev)	\
> +	rwsem_release(&(sb)->s_writers.lock_map[(lev)-1], 1, _THIS_IP_)
> +
>  /**
>   * sb_end_write - drop write access to a superblock
>   * @sb: the super we wrote to
> -- 
> 1.5.5.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR
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