tree 4e944139b9e45c4af910c517b57f2d9bc7c81a1a
parent 01fc48e8929e45e67527200017cff4e74e4ba054
author Theodore Ts'o <tytso@mit.edu> 1345211297 -0400
committer Theodore Ts'o <tytso@mit.edu> 1345211297 -0400

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>