linux-kernel - Re: [PATCH] f2fs: move f2fs_balance_fs from truncate to punch

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Message-id: <1365497702.4353.67.camel@kjgkr>
Date:	Tue, 09 Apr 2013 17:55:02 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	Jason Hrycay <jhrycay@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net, C.Fries@...orola.com,
	jason.hrycay@...orola.com
Subject: Re: [PATCH] f2fs: move f2fs_balance_fs from truncate to punch_hole

Hi,

2013-04-08 (월), 20:16 -0500, Jason Hrycay:
> From: Jason Hrycay <jason.hrycay@...orola.com>
> 
> Move the f2fs_balance_fs out of the truncate_hole function and only
> perform that in punch_hole use case.  The commit:
> 
>   ed60b1644e7f7e5dd67d21caf7e4425dff05dad0
> 
> intended to do this but moved it into truncate_hole to cover more
> cases.  However, a deadlock scenario is possible when deleting an inode
> entry under specific conditions:
> 
>  f2fs_delete_entry()
>      mutex_lock_op(sbi, DENTRY_OPS);
>      truncate_hole()
>          f2fs_balance_fs()
>              mutex_lock(&sbi->gc_mutex);
>              f2fs_gc()
>                  write_checkpoint()
>                      block_operations()
>                          mutex_lock_op(sbi, DENTRY_OPS);
> 
> Lets move it into the punch_hole case to cover the original intent of
> avoiding it during fallocate's expand_inode_data case.

Agreed.
Thanks,

> 
> Change-Id: I29f8ea1056b0b88b70ba8652d901b6e8431bb27e
> Signed-off-by: Jason Hrycay <jason.hrycay@...orola.com>
> ---
>  fs/f2fs/file.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index e031f57..155b362 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -390,8 +390,6 @@ int truncate_hole(struct inode *inode, pgoff_t pg_start, pgoff_t pg_end)
>  		struct dnode_of_data dn;
>  		struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
> 
> -		f2fs_balance_fs(sbi);
> -
>  		mutex_lock_op(sbi, DATA_TRUNC);
>  		set_new_dnode(&dn, inode, NULL, NULL, 0);
>  		err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
> @@ -435,6 +433,9 @@ static int punch_hole(struct inode *inode, loff_t offset, loff_t len, int mode)
>  		if (pg_start < pg_end) {
>  			struct address_space *mapping = inode->i_mapping;
>  			loff_t blk_start, blk_end;
> +			struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
> +
> +			f2fs_balance_fs(sbi);
> 
>  			blk_start = pg_start << PAGE_CACHE_SHIFT;
>  			blk_end = pg_end << PAGE_CACHE_SHIFT;
> -- 1.8.0

-- 
Jaegeuk Kim
Samsung

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