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Brian Behlendorf 2cbb06b561 Restructure per-filesystem reclaim
Originally when the ARC prune callback was introduced the idea was
to register a single callback for the ZPL.  The ARC could invoke this
call back if it needed the ZPL to drop dentries, inodes, or other
cache objects which might be pinning buffers in the ARC.  The ZPL
would iterate over all ZFS super blocks and perform the reclaim.

For the most part this design has worked well but due to limitations
in 2.6.35 and earlier kernels there were some problems.  This patch
is designed to address those issues.

1) iterate_supers_type() is not provided by all kernels which makes
it impossible to safely iterate over all zpl_fs_type filesystems in
a single callback.  The most straight forward and portable way to
resolve this is to register a callback per-filesystem during mount.
The arc_*_prune_callback() functions have always supported multiple
callbacks so this is functionally a very small change.

2) Commit 050d22b removed the non-portable shrink_dcache_memory()
and shrink_icache_memory() functions and didn't replace them with
equivalent functionality.  This meant that for Linux 3.1 and older
kernels the ARC had no mechanism to drop dentries and inodes from
the caches if needed.  This patch adds that missing functionality
by calling shrink_dcache_parent() to release dentries which may be
pinning inodes.  This will result in all unused cache entries being
dropped which is a bit heavy handed but it's the only interface
available for old kernels.

3) A zpl_drop_inode() callback is registered for kernels older than
2.6.35 which do not support the .evict_inode callback.  This ensures
that when the last reference on an inode is dropped it is immediately
removed from the cache.  If this isn't done than inode can end up on
the global unused LRU with no mechanism available to ZFS to drop them.
Since the ARC buffers are not dropped the hottest inodes can still
be recreated without performing disk IO.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Pavel Snajdr <snajpa@snajpa.net>
Issue #3160
2015-03-20 10:35:20 -07:00
cmd Install arc_summary.py 2015-03-03 13:38:17 -08:00
config Linux 4.0 compat: bdi_setup_and_register() __must_check 2015-03-16 10:56:26 -07:00
contrib Add bash completions by Aneurin Price. 2014-08-06 15:03:28 -07:00
dracut Fix error in dracut script if not using ZFS root 2015-02-17 16:15:16 -08:00
etc Actually source /etc/sysconfig/zfs instead of /etc/default/zfs 2015-03-09 17:13:04 -07:00
include Restructure per-filesystem reclaim 2015-03-20 10:35:20 -07:00
lib Increase Linux pipe buffer size on 'zfs receive' 2015-03-20 10:03:34 -07:00
man Restructure per-filesystem reclaim 2015-03-20 10:35:20 -07:00
module Restructure per-filesystem reclaim 2015-03-20 10:35:20 -07:00
rpm Fix typo in %post scriptlet lines 2014-12-18 18:38:33 -08:00
scripts Set zfs_autoimport_disable default value to 1 2015-02-17 16:09:41 -08:00
udev Open pools asynchronously after module load 2013-07-03 09:24:38 -07:00
.gitignore Ignore *.{deb,rpm,tar.gz} files in the top directory. 2013-04-24 16:18:59 -07:00
.gitmodules Add zimport.sh compatibility test script 2014-02-21 12:10:31 -08:00
AUTHORS Add a missing > to AUTHORS 2014-09-02 14:18:53 -07:00
autogen.sh build: do not call boilerplate ourself 2013-04-02 10:55:20 -07:00
configure.ac Fix warning about AM_INIT_AUTOMAKE arguments 2015-03-18 09:18:57 -07:00
copy-builtin Consistent menuconfig name 2012-08-26 13:49:37 -07:00
COPYRIGHT Refresh links to web site 2013-03-06 15:46:41 -08:00
DISCLAIMER Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
Makefile.am Kernel header installation should respect --prefix 2014-10-28 09:37:06 -07:00
META Make license compatibility checks consistent 2014-10-17 14:58:38 -07:00
OPENSOLARIS.LICENSE Add CDDL license file 2008-12-01 14:49:34 -08:00
README.markdown Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
zfs-script-config.sh.in Initial implementation of zed (ZFS Event Daemon) 2014-04-02 13:10:03 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

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