From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756603Ab1FFEmk (ORCPT ); Mon, 6 Jun 2011 00:42:40 -0400 Received: from smtp-out.google.com ([216.239.44.51]:11704 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755687Ab1FFEmj (ORCPT ); Mon, 6 Jun 2011 00:42:39 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version:content-type; b=bL3P3tHQM3nOeddwRced5SdFGAiSJ7BuKYVwvC7kicF/xpYJLr7uOFlBqj4z+Ql6UO G2iORX4bzoFjkvpubQdg== Date: Sun, 5 Jun 2011 21:42:39 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@sister.anvils To: Andrew Morton cc: Tim Chen , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 14/14] tmpfs: no need to use i_lock In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (LSU 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.36's 7e496299d4d2 to make tmpfs scalable with percpu_counter used inode->i_lock in place of sbinfo->stat_lock around i_blocks updates; but that was adverse to scalability, and unnecessary, since info->lock is already held there in the fast paths. Remove those uses of i_lock, and add info->lock in the three error paths where it's then needed across shmem_free_blocks(). It's not actually needed across shmem_unacct_blocks(), but they're so often paired that it looks wrong to split them apart. Signed-off-by: Hugh Dickins Acked-by: Tim Chen --- mm/shmem.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) --- linux.orig/mm/shmem.c 2011-06-05 17:53:42.948796800 -0700 +++ linux/mm/shmem.c 2011-06-05 19:27:33.248715783 -0700 @@ -241,9 +241,7 @@ static void shmem_free_blocks(struct ino struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); if (sbinfo->max_blocks) { percpu_counter_add(&sbinfo->used_blocks, -pages); - spin_lock(&inode->i_lock); inode->i_blocks -= pages*BLOCKS_PER_PAGE; - spin_unlock(&inode->i_lock); } } @@ -432,9 +430,7 @@ static swp_entry_t *shmem_swp_alloc(stru sbinfo->max_blocks - 1) >= 0) return ERR_PTR(-ENOSPC); percpu_counter_inc(&sbinfo->used_blocks); - spin_lock(&inode->i_lock); inode->i_blocks += BLOCKS_PER_PAGE; - spin_unlock(&inode->i_lock); } spin_unlock(&info->lock); @@ -1421,9 +1417,7 @@ repeat: shmem_acct_block(info->flags)) goto nospace; percpu_counter_inc(&sbinfo->used_blocks); - spin_lock(&inode->i_lock); inode->i_blocks += BLOCKS_PER_PAGE; - spin_unlock(&inode->i_lock); } else if (shmem_acct_block(info->flags)) goto nospace; @@ -1434,8 +1428,10 @@ repeat: spin_unlock(&info->lock); filepage = shmem_alloc_page(gfp, info, idx); if (!filepage) { + spin_lock(&info->lock); shmem_unacct_blocks(info->flags, 1); shmem_free_blocks(inode, 1); + spin_unlock(&info->lock); error = -ENOMEM; goto failed; } @@ -1449,8 +1445,10 @@ repeat: current->mm, GFP_KERNEL); if (error) { page_cache_release(filepage); + spin_lock(&info->lock); shmem_unacct_blocks(info->flags, 1); shmem_free_blocks(inode, 1); + spin_unlock(&info->lock); filepage = NULL; goto failed; } @@ -1480,10 +1478,10 @@ repeat: * be done automatically. */ if (ret) { - spin_unlock(&info->lock); - page_cache_release(filepage); shmem_unacct_blocks(info->flags, 1); shmem_free_blocks(inode, 1); + spin_unlock(&info->lock); + page_cache_release(filepage); filepage = NULL; if (error) goto failed;