linux-ext4 - Re: [PATCH] logsave : Avoid unnecessary backgrounding of logsave in case of failures

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Message-ID: <20081010183157.GD8645@mit.edu>
Date:	Fri, 10 Oct 2008 14:31:57 -0400
From:	Theodore Tso <tytso@....edu>
To:	Manish Katiyar <mkatiyar@...il.com>
Cc:	ext4 <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] logsave : Avoid unnecessary backgrounding of logsave
	in case of failures

On Tue, Oct 07, 2008 at 11:14:11PM +0530, Manish Katiyar wrote:
> Hi Ted,
> 
> I am not sure why we wan't to background the logsave and keep retrying
> opening the fd in case of failures. 

That's one of the main reason why logsave exists; the filesystem
containing /var/log might not be mounted, or the root filesystem may
be mounted read-only, and so the log file can't be written until the
filesystem is remounted r/w or /var is mounted.

> But there may be situations when we will never be able to succeed
> and thus create unnecessary process. For example invoking it
> 
> /home/mkatiyar/sbin> ./logsave /testfile ls

The main use of logsave was in init.d scripts.  So I didn't really
worry about the permissoin denied case.  Perhaps logsave should just
fail hard and not even run the command if there is a permission denied
error.  That would certainly be simpler...

> +static void should_background(int err, int *nobackground) {
> +	switch (err) {
> +		case EPERM:
> +		case EACCES:
> +			*nobackground = err;
> +			break;
> +		default :
> +			*nobackground = 0;
> +	}
> +	return ;
> +}

Why is this its own function?

						- Ted
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