From 55f841ce9395a72c6285fbcc4c403c0c786e1c74 Mon Sep 17 00:00:00 2001
From: Glauber Costa
Date: Wed, 28 Aug 2013 10:17:53 +1000
Subject: super: fix calculation of shrinkable objects for small numbers

The sysctl knob sysctl_vfs_cache_pressure is used to determine which
percentage of the shrinkable objects in our cache we should actively try
to shrink.

It works great in situations in which we have many objects (at least more
than 100), because the aproximation errors will be negligible.  But if
this is not the case, specially when total_objects < 100, we may end up
concluding that we have no objects at all (total / 100 = 0, if total <
100).

This is certainly not the biggest killer in the world, but may matter in
very low kernel memory situations.

Signed-off-by: Glauber Costa <glommer@openvz.org>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Carlos Maiolino <cmaiolino@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Rientjes <rientjes@google.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: J. Bruce Fields <bfields@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/quota/dquot.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

(limited to 'fs/quota')

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 9a702e193538..13eee847605c 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -719,9 +719,8 @@ static int shrink_dqcache_memory(struct shrinker *shrink,
 		prune_dqcache(nr);
 		spin_unlock(&dq_list_lock);
 	}
-	return ((unsigned)
-		percpu_counter_read_positive(&dqstats.counter[DQST_FREE_DQUOTS])
-		/100) * sysctl_vfs_cache_pressure;
+	return vfs_pressure_ratio(
+	percpu_counter_read_positive(&dqstats.counter[DQST_FREE_DQUOTS]));
 }
 
 static struct shrinker dqcache_shrinker = {
-- 
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