linux-ext4 - Re: [PATCH 2/2 -v2] e2image: attempt to use ftruncate64 to set i

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Date:	Fri, 17 Feb 2012 21:19:43 +0100 (CET)
From:	Lukas Czerner <lczerner@...hat.com>
To:	"Theodore Ts'o" <tytso@....edu>
cc:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH 2/2 -v2] e2image: attempt to use ftruncate64 to set i_size
 for raw images

On Fri, 17 Feb 2012, Theodore Ts'o wrote:

> If ftruncate64() exists, try to use it to set i_size.  This isn't
> guaranteed to work, per SuSv3, but if it doesn't work, it's guaranteed
> to return an error.  So for file systems and/or operating systems that
> don't support extending i_size via ftruncate64(), fall back to writing
> the trailing null.

Looks good, thanks.

-Lukas

> 
> Signed-off-by: "Theodore Ts'o" <tytso@....edu>
> ---
> 
> Oops, sent the wrong version of the patch.  My bad.
> 
>  misc/e2image.c |   11 +++++++++++
>  1 files changed, 11 insertions(+), 0 deletions(-)
> 
> diff --git a/misc/e2image.c b/misc/e2image.c
> index 3cb92fe..93359cf 100644
> --- a/misc/e2image.c
> +++ b/misc/e2image.c
> @@ -510,8 +510,19 @@ static void output_meta_data_blocks(ext2_filsys fs, int fd)
>  			}
>  		}
>  	}
> +#ifdef HAVE_FTRUNCATE64
> +	if (sparse) {
> +		ext2_loff_t offset = ext2fs_llseek(fd, sparse, SEEK_CUR);
> +
> +		if (offset < 0)
> +			lseek_error_and_exit(errno);
> +		if (ftruncate64(fd, offset) < 0)
> +			write_block(fd, zero_buf, -1, 1, -1);
> +	}
> +#else
>  	if (sparse)
>  		write_block(fd, zero_buf, sparse-1, 1, -1);
> +#endif
>  	ext2fs_free_mem(&zero_buf);
>  	ext2fs_free_mem(&buf);
>  }
> 

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