From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756095Ab1HEAgn (ORCPT ); Thu, 4 Aug 2011 20:36:43 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:14033 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753772Ab1HEAgi (ORCPT ); Thu, 4 Aug 2011 20:36:38 -0400 From: Glauber Costa To: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, containers@lists.linux-foundation.org, Pavel Emelyanov , Al Viro , Hugh Dickins , Nick Piggin , Andrea Arcangeli , Rik van Riel , Dave Hansen , James Bottomley , David Chinner , Glauber Costa Subject: [PATCH v2 3/4] limit nr_dentries per superblock Date: Fri, 5 Aug 2011 04:35:43 +0400 Message-Id: <1312504544-1108-4-git-send-email-glommer@parallels.com> X-Mailer: git-send-email 1.7.6 In-Reply-To: <1312504544-1108-1-git-send-email-glommer@parallels.com> References: <1312504544-1108-1-git-send-email-glommer@parallels.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch lays the foundation for us to limit the dcache size. Each super block can have only a maximum amount of dentries under its sub-tree. Allocation fails if we we're over limit and the cache can't be pruned to free up space for the newcomers. Signed-off-by: Glauber Costa CC: Dave Chinner --- fs/dcache.c | 25 +++++++++++++++++++++++++ fs/super.c | 1 + include/linux/fs.h | 1 + 3 files changed, 27 insertions(+), 0 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index ac19d24..52a0faf 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1180,6 +1180,28 @@ void shrink_dcache_parent(struct dentry * parent) } EXPORT_SYMBOL(shrink_dcache_parent); +static int dcache_mem_check(struct super_block *sb) +{ + int i; + int nr_dentry; + struct shrink_control sc = { + .gfp_mask = GFP_KERNEL, + }; + + do { + nr_dentry = 0; + for_each_possible_cpu(i) + nr_dentry += per_cpu(*sb->s_nr_dentry, i); + + if (nr_dentry < sb->s_nr_dentry_max) + return 0; + + /* nr_pages = 1, lru_pages = 0 should get delta ~ 2 */ + } while (shrink_one_shrinker(&sb->s_shrink, &sc, 1, 0)); + + return -ENOMEM; +} + /** * __d_alloc - allocate a dcache entry * @sb: filesystem it will belong to @@ -1195,6 +1217,9 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) struct dentry *dentry; char *dname; + if (dcache_mem_check(sb)) + return NULL; + dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); if (!dentry) return NULL; diff --git a/fs/super.c b/fs/super.c index 9345385..d9bcae8 100644 --- a/fs/super.c +++ b/fs/super.c @@ -130,6 +130,7 @@ static struct super_block *alloc_super(struct file_system_type *type) } for_each_possible_cpu(i) *per_cpu_ptr(s->s_nr_dentry, i) = 0; + s->s_nr_dentry_max = INT_MAX; #ifdef CONFIG_SMP s->s_files = alloc_percpu(struct list_head); diff --git a/include/linux/fs.h b/include/linux/fs.h index 35113fd..e90dcb4 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1399,6 +1399,7 @@ struct super_block { struct list_head s_dentry_lru; /* unused dentry lru */ int s_nr_dentry_unused; /* # of dentry on lru */ + int s_nr_dentry_max; /* max # of dentry on this sb*/ int __percpu *s_nr_dentry; /* # of dentry on this sb */ /* s_inode_lru_lock protects s_inode_lru and s_nr_inodes_unused */ -- 1.7.6