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From: David Sterba <dsterba@suse.cz>
To: Josef Bacik <josef@toxicpanda.com>
Cc: linux-btrfs@vger.kernel.org, kernel-team@fb.com, stable@vger.kernel.org
Subject: Re: [PATCH] btrfs: save i_size in compress_file_range
Date: Wed, 23 Oct 2019 18:51:02 +0200	[thread overview]
Message-ID: <20191023165102.GC3001@twin.jikos.cz> (raw)
In-Reply-To: <20191011130354.8232-1-josef@toxicpanda.com>

On Fri, Oct 11, 2019 at 09:03:54AM -0400, Josef Bacik wrote:
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -474,6 +474,7 @@ static noinline int compress_file_range(struct async_chunk *async_chunk)
>  	u64 start = async_chunk->start;
>  	u64 end = async_chunk->end;
>  	u64 actual_end;
> +	loff_t i_size = i_size_read(inode);
>  	int ret = 0;
>  	struct page **pages = NULL;
>  	unsigned long nr_pages;
> @@ -488,7 +489,13 @@ static noinline int compress_file_range(struct async_chunk *async_chunk)
>  	inode_should_defrag(BTRFS_I(inode), start, end, end - start + 1,
>  			SZ_16K);
>  
> -	actual_end = min_t(u64, i_size_read(inode), end + 1);
> +	/*
> +	 * We need to save i_size before now because it could change in between
> +	 * us evaluating the size and assigning it.  This is because we lock and
> +	 * unlock the page in truncate and fallocate, and then modify the i_size
> +	 * later on.
> +	 */
> +	actual_end = min_t(u64, i_size, end + 1);

Ping. This is not a future proof fix, please update the changelog and
code according to the reply I sent.

  parent reply	other threads:[~2019-10-23 16:50 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-11 13:03 [PATCH] btrfs: save i_size in compress_file_range Josef Bacik
2019-10-11 15:28 ` Filipe Manana
2019-10-11 17:15   ` Josef Bacik
2019-10-14 11:52 ` David Sterba
2019-10-23 16:51 ` David Sterba [this message]
2019-11-04 19:59   ` David Sterba

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