Re: [PATCH 3/3] ext4: disable COLLAPSE_RANGE for bigalloc

["Lukáš Czerner" <lczerner@redhat.com>]

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On Thu, 17 Apr 2014, Namjae Jeon wrote:

> Date: Thu, 17 Apr 2014 07:30:54 +0900
> From: Namjae Jeon <namjae.jeon@samsung.com>
> To: Theodore Ts'o <tytso@mit.edu>
> Cc: linux-ext4 <linux-ext4@vger.kernel.org>,
>     Lukáš Czerner <lczerner@redhat.com>
> Subject: [PATCH 3/3] ext4: disable COLLAPSE_RANGE for bigalloc
> 
> From: Namjae Jeon <namjae.jeon@samsung.com>
> 
> Once COLLAPSE RANGE is be disable for ext4 with bigalloc feature till finding
> root-cause of problem. It will be enable with fixing that regression of
> xfstest(generic 075 and 091) again.
> 
> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
> ---
>  fs/ext4/extents.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index a64242f..8d45ef8 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -5461,6 +5461,11 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
>  		goto out_mutex;
>  	}
>  
> +	if (EXT4_SB(inode->i_sb)->s_cluster_ratio > 1) {
> +		ret = -EOPNOTSUPP;
> +		goto out_mutex;
> +	}
> +

I do not think we need to hold mutex for this. You can move it to
the beginning of the function preferably right after S_ISREG check.

Otherwise it looks ok, but it would be better if we could fix it :)

Reviewed-by: Lukas Czerner <lczerner@redhat.com>

>  	truncate_pagecache_range(inode, ioffset, -1);
>  
>  	/* Wait for existing dio to complete */
>