linux-kernel - Re: [PATCH] eCryptfs: Fix dentry handling on create error, unlink, and inode destroy

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Date:	Tue, 8 Jan 2008 14:42:15 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Michael Halcrow <mhalcrow@...ibm.com>
Cc:	linux-kernel@...r.kernel.org, shaggy@...ibm.com,
	sandeen@...hat.com, jmoyer@...hat.com
Subject: Re: [PATCH] eCryptfs: Fix dentry handling on create error, unlink,
 and inode destroy

On Tue, 8 Jan 2008 15:58:07 -0600
Michael Halcrow <mhalcrow@...ibm.com> wrote:

> > >  	rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
> > >  				directory_inode->i_sb, 0);
> > 
> > Will this cause an undesirable log storm if the underlying fs runs
> > out of space?
> 
> When you're bumping up against the end of your storage space, you will
> get a lot more that just this message in your logs. There are printk's
> in ecryptfs_write_lower(), ecryptfs_encrypt_page(), ecryptfs_write(),
> and ecryptfs_write_metadata_to_contents() that will get pretty
> noisy. Is it worth wrapping those in a higher level of verbosity?

The consequences of this can actually be pretty harmful.  syslogd typically
does sychronous writes so a random full disk can cause a seek storm over on
the log disk and a runaway ecryptfs-using application could pretty quickly
exhaust the space on the log disk.

So I'd suggest that sometime you go through the fs and find any such
user-triggerable printks and fix them up.  The most robust way of fixing
them up would be to delete them, or make them dependent on
CONFIG_ECRYPTFS_DEBUG.  Fiddling with the facility levels would help, but
it just lessens the probability rather than fixing it completely.

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