From 4d8e7055a4058ee191296699803c5090e14f0dff Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Sun, 5 May 2019 12:15:49 +0300 Subject: fsnotify: fix unlink performance regression __fsnotify_parent() has an optimization in place to avoid unneeded take_dentry_name_snapshot(). When fsnotify_nameremove() was changed not to call __fsnotify_parent(), we left out the optimization. Kernel test robot reported a 5% performance regression in concurrent unlink() workload. Reported-by: kernel test robot Link: https://lore.kernel.org/lkml/20190505062153.GG29809@shao2-debian/ Link: https://lore.kernel.org/linux-fsdevel/20190104090357.GD22409@quack2.suse.cz/ Fixes: 5f02a8776384 ("fsnotify: annotate directory entry modification events") CC: stable@vger.kernel.org Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- fs/notify/fsnotify.c | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) (limited to 'fs/notify') diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index df06f3da166c..e8d3f349b7f2 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -107,6 +107,47 @@ void fsnotify_sb_delete(struct super_block *sb) fsnotify_clear_marks_by_sb(sb); } +/* + * fsnotify_nameremove - a filename was removed from a directory + * + * This is mostly called under parent vfs inode lock so name and + * dentry->d_parent should be stable. However there are some corner cases where + * inode lock is not held. So to be on the safe side and be reselient to future + * callers and out of tree users of d_delete(), we do not assume that d_parent + * and d_name are stable and we use dget_parent() and + * take_dentry_name_snapshot() to grab stable references. + */ +void fsnotify_nameremove(struct dentry *dentry, int isdir) +{ + struct dentry *parent; + struct name_snapshot name; + __u32 mask = FS_DELETE; + + /* d_delete() of pseudo inode? (e.g. __ns_get_path() playing tricks) */ + if (IS_ROOT(dentry)) + return; + + if (isdir) + mask |= FS_ISDIR; + + parent = dget_parent(dentry); + /* Avoid unneeded take_dentry_name_snapshot() */ + if (!(d_inode(parent)->i_fsnotify_mask & FS_DELETE) && + !(dentry->d_sb->s_fsnotify_mask & FS_DELETE)) + goto out_dput; + + take_dentry_name_snapshot(&name, dentry); + + fsnotify(d_inode(parent), mask, d_inode(dentry), FSNOTIFY_EVENT_INODE, + name.name, 0); + + release_dentry_name_snapshot(&name); + +out_dput: + dput(parent); +} +EXPORT_SYMBOL(fsnotify_nameremove); + /* * Given an inode, first check if we care what happens to our children. Inotify * and dnotify both tell their parents about events. If we care about any event -- cgit v1.2.3-55-g7522