Errata overview
Errata ID 21
Date 2016-11-23
Source package linux
Fixed in version 3.16.38-0.1~bpo70+1.216.201611212052
This update addresses the following issue:
* The mount-point option "no_mbcache" was added for ext4 file systems to
  disable the "Filesystem Meta Information Block Cache (mbcache)". The cache
  is used to manage shared Extended Attributes (EAs), which are also used to
  store Access Control Lists (ACLs) for files and directories. For some
  work-loads which use EAs with many different values the cache has
  performance issues and can dead-lock the system in certain cases. Samba is
  one example which uses EAs to store the DOS attributes and NT-ACLs.
  The cache can be disabled by re-mounting the file system using
    mount -o remount,no_mbcache "$fs"
  or by adding the option "no_mbcache" in '/etc/fstab' and rebooting the
Additional notes This is the 1st part of the update.
UCS Bug number #42984