From: Dmitry Monakhov Subject: [PATCH] ext4: optimize orphan_list handling for ext4_setattr Date: Mon, 25 Oct 2010 11:06:42 +0400 Message-ID: <87r5fevji5.fsf@dmon-lap.sw.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: linux-ext4@vger.kernel.org, Ted Ts'o Return-path: Received: from mail-ey0-f174.google.com ([209.85.215.174]:59454 "EHLO mail-ey0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751804Ab0JYHGw (ORCPT ); Mon, 25 Oct 2010 03:06:52 -0400 Received: by eye27 with SMTP id 27so3861648eye.19 for ; Mon, 25 Oct 2010 00:06:51 -0700 (PDT) Sender: linux-ext4-owner@vger.kernel.org List-ID: Surprisingly chown() on ext4 is not SMP scalable operation. Due to unconditional orphan_del(NULL, inode) in ext4_setattr() result in significant performance overhead because of global orphan mutex, especially in no-journal mode (where orphan_add() is noop). It is possible to skip explicit orphan_del if possible. Results of fchown() micro-benchmark in no-journal mode while (1) { iteration++; fchown(fd, uid, gid); fchown(fd, uid + 1, gid + 1) } measured: iterations per millisecond | nr_tasks | w/o patch | with patch | | 1 | 142 | 185 | | 4 | 109 | 642 | Signed-off-by: Dmitry Monakhov --- fs/ext4/inode.c | 10 +++++++--- 1 files changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 18eed80..a16097b 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5540,6 +5540,7 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr) { struct inode *inode = dentry->d_inode; int error, rc = 0; + int orphan = 0; const unsigned int ia_valid = attr->ia_valid; error = inode_change_ok(inode, attr); @@ -5595,8 +5596,10 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr) error = PTR_ERR(handle); goto err_out; } - - error = ext4_orphan_add(handle, inode); + if (ext4_handle_valid(handle)) { + error = ext4_orphan_add(handle, inode); + orphan = 1; + } EXT4_I(inode)->i_disksize = attr->ia_size; rc = ext4_mark_inode_dirty(handle, inode); if (!error) @@ -5608,6 +5611,7 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr) attr->ia_size); if (error) { /* Do as much error cleanup as possible */ + orphan = 0; handle = ext4_journal_start(inode, 3); if (IS_ERR(handle)) { ext4_orphan_del(NULL, inode); @@ -5636,7 +5640,7 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr) * If the call to ext4_truncate failed to get a transaction handle at * all, we need to clean up the in-core orphan list manually. */ - if (inode->i_nlink) + if (orphan && inode->i_nlink) ext4_orphan_del(NULL, inode); if (!rc && (ia_valid & ATTR_MODE)) -- 1.6.6.1