From: Theodore Ts'o <tytso@mit.edu>
Date: Fri, 17 Aug 2012 13:48:17 +0000 (-0400)
Subject: ext4: add max_dir_size_kb mount option
X-Git-Tag: v3.7-rc1~91^2~66
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=df981d03eeff7971ac7e6ff37000bfa702327ef1;p=pandora-kernel.git

ext4: add max_dir_size_kb mount option

Very large directories can cause significant performance problems, or
perhaps even invoke the OOM killer, if the process is running in a
highly constrained memory environment (whether it is VM's with a small
amount of memory or in a small memory cgroup).

So it is useful, in cloud server/data center environments, to be able
to set a filesystem-wide cap on the maximum size of a directory, to
ensure that directories never get larger than a sane size.  We do this
via a new mount option, max_dir_size_kb.  If there is an attempt to
grow the directory larger than max_dir_size_kb, the system call will
return ENOSPC instead.

Google-Bug-Id: 6863013

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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