From ce06e0b21d6732a2bab10a585a3ec6909499be28 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Fri, 18 Sep 2009 13:05:48 -0700 Subject: vfs: optimize touch_time() too Do a similar optimization as earlier for touch_atime. Getting the lock in mnt_get_write is relatively costly, so try all avenues to avoid it first. This patch is careful to still only update inode fields inside the lock region. This didn't show up in benchmarks, but it's easy enough to do. [akpm@linux-foundation.org: fix typo in comment] [hugh.dickins@tiscali.co.uk: fix inverted test of mnt_want_write_file()] Signed-off-by: Andi Kleen Cc: Christoph Hellwig Cc: Valerie Aurora Cc: Al Viro Cc: Dave Hansen Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/inode.c | 43 +++++++++++++++++++++++-------------------- 1 file changed, 23 insertions(+), 20 deletions(-) diff --git a/fs/inode.c b/fs/inode.c index 31168fd45bd..4d8e3be5597 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -1461,34 +1461,37 @@ void file_update_time(struct file *file) { struct inode *inode = file->f_path.dentry->d_inode; struct timespec now; - int sync_it = 0; - int err; + enum { S_MTIME = 1, S_CTIME = 2, S_VERSION = 4 } sync_it = 0; + /* First try to exhaust all avenues to not sync */ if (IS_NOCMTIME(inode)) return; - err = mnt_want_write_file(file); - if (err) - return; - now = current_fs_time(inode->i_sb); - if (!timespec_equal(&inode->i_mtime, &now)) { - inode->i_mtime = now; - sync_it = 1; - } + if (!timespec_equal(&inode->i_mtime, &now)) + sync_it = S_MTIME; - if (!timespec_equal(&inode->i_ctime, &now)) { - inode->i_ctime = now; - sync_it = 1; - } + if (!timespec_equal(&inode->i_ctime, &now)) + sync_it |= S_CTIME; - if (IS_I_VERSION(inode)) { - inode_inc_iversion(inode); - sync_it = 1; - } + if (IS_I_VERSION(inode)) + sync_it |= S_VERSION; - if (sync_it) - mark_inode_dirty_sync(inode); + if (!sync_it) + return; + + /* Finally allowed to write? Takes lock. */ + if (mnt_want_write_file(file)) + return; + + /* Only change inode inside the lock region */ + if (sync_it & S_VERSION) + inode_inc_iversion(inode); + if (sync_it & S_CTIME) + inode->i_ctime = now; + if (sync_it & S_MTIME) + inode->i_mtime = now; + mark_inode_dirty_sync(inode); mnt_drop_write(file->f_path.mnt); } EXPORT_SYMBOL(file_update_time); -- cgit v1.2.3