linux-kernel - Re: [RFC PATCH] coredump: fix incomplete core file created when dump

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Message-ID: <20141022165530.GA30358@redhat.com>
Date:	Wed, 22 Oct 2014 18:55:30 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Victor Kamensky <victor.kamensky@...aro.org>
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] coredump: fix incomplete core file created when
	dump_skip was used last

On 10/21, Victor Kamensky wrote:
>
> +static int dump_write_last_byte(struct coredump_params *cprm)
> +{
> +	char lastbyte = 0;
> +	struct file *file = cprm->file;
> +
> +	if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
> +		if (dump_interrupted() ||
> +		    file->f_op->llseek(file, -1, SEEK_CUR) < 0)
> +			return 0;
> +		if (!dump_emit(cprm, &lastbyte, 1))
> +			return 0;
> +	}
> +	return 1;
> +}

Perhaps do_truncate(cprm.file->f_path.dentry, ->f_pos) makes more sense?

and unless I missed something cprm->last_op_status can be avoided, we can
simply check f_pos != i_size_read() at the end?

Oleg.

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