Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752894Ab0K0K0Y (ORCPT ); Sat, 27 Nov 2010 05:26:24 -0500 Received: from ipmail04.adl6.internode.on.net ([150.101.137.141]:34794 "EHLO ipmail04.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752876Ab0K0K0R (ORCPT ); Sat, 27 Nov 2010 05:26:17 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApcFAO1p8Ex5Lcx2/2dsb2JhbACVC44Acr12hUcEimGFFA Message-Id: <41cf0f67bed97948600e55e25a1081523a699afe.1290852959.git.npiggin@kernel.dk> In-Reply-To: References: From: Nick Piggin Date: Sat, 27 Nov 2010 20:44:58 +1100 Subject: [PATCH 28/46] fs: use RCU in shrink_dentry_list to reduce lock nesting To: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2607 Lines: 108 Signed-off-by: Nick Piggin --- fs/dcache.c | 38 +++++++++++++++++++++----------------- 1 files changed, 21 insertions(+), 17 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 5a7c328..4dbcb6c 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -580,16 +580,16 @@ static void shrink_dentry_list(struct list_head *list) { struct dentry *dentry; + rcu_read_lock(); while (!list_empty(list)) { struct dentry *parent; dentry = list_entry(list->prev, struct dentry, d_lru); - if (!spin_trylock(&dentry->d_lock)) { -relock1: - spin_unlock(&dcache_lru_lock); - cpu_relax(); - spin_lock(&dcache_lru_lock); + /* Don't need RCU dereference because we recheck under lock */ + spin_lock(&dentry->d_lock); + if (dentry != list_entry(list->prev, struct dentry, d_lru)) { + spin_unlock(&dentry->d_lock); continue; } @@ -599,14 +599,16 @@ relock1: * it - just keep it off the LRU list. */ if (dentry->d_count) { - __dentry_lru_del(dentry); + dentry_lru_del(dentry); spin_unlock(&dentry->d_lock); continue; } + if (!spin_trylock(&dcache_inode_lock)) { -relock2: +relock: spin_unlock(&dentry->d_lock); - goto relock1; + cpu_relax(); + continue; } if (IS_ROOT(dentry)) parent = NULL; @@ -614,15 +616,15 @@ relock2: parent = dentry->d_parent; if (parent && !spin_trylock(&parent->d_lock)) { spin_unlock(&dcache_inode_lock); - goto relock2; + goto relock; } - __dentry_lru_del(dentry); - spin_unlock(&dcache_lru_lock); + dentry_lru_del(dentry); + rcu_read_unlock(); prune_one_dentry(dentry, parent); - /* dcache_inode_lock and dentry->d_lock dropped */ - spin_lock(&dcache_lru_lock); + rcu_read_lock(); } + rcu_read_unlock(); } /** @@ -671,13 +673,13 @@ relock: break; } } - - *count = cnt; - shrink_dentry_list(&tmp); - if (!list_empty(&referenced)) list_splice(&referenced, &sb->s_dentry_lru); spin_unlock(&dcache_lru_lock); + + shrink_dentry_list(&tmp); + + *count = cnt; } /** @@ -769,7 +771,9 @@ void shrink_dcache_sb(struct super_block *sb) spin_lock(&dcache_lru_lock); while (!list_empty(&sb->s_dentry_lru)) { list_splice_init(&sb->s_dentry_lru, &tmp); + spin_unlock(&dcache_lru_lock); shrink_dentry_list(&tmp); + spin_lock(&dcache_lru_lock); } spin_unlock(&dcache_lru_lock); } -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/