From 277a2094c5158961610c5c3f1be745bd9a335822 Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Tue, 10 Aug 2021 18:12:20 +0300
Subject: [PATCH] fsnotify: optimize the case of no marks of any type

References: bsc#1190120 (Fsnotify functional and performance backports)
Patch-mainline: v5.15-rc1
Git-commit: e43de7f0862b8598cd1ef440e3b4701cd107ea40

Add a simple check in the inline helpers to avoid calling fsnotify()
and __fsnotify_parent() in case there are no marks of any type
(inode/sb/mount) for an inode's sb, so there can be no objects
of any type interested in the event.

Link: https://lore.kernel.org/r/20210810151220.285179-5-amir73il@gmail.com
Reviewed-by: Matthew Bobrowski <repnop@google.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 include/linux/fsnotify.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index f8acddcf54fb..12d3a7d308ab 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -30,6 +30,9 @@ static inline void fsnotify_name(struct inode *dir, __u32 mask,
 				 struct inode *child,
 				 const struct qstr *name, u32 cookie)
 {
+	if (atomic_long_read(&dir->i_sb->s_fsnotify_connectors) == 0)
+		return;
+
 	fsnotify(mask, child, FSNOTIFY_EVENT_INODE, dir, name, NULL, cookie);
 }
 
@@ -41,6 +44,9 @@ static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry,
 
 static inline void fsnotify_inode(struct inode *inode, __u32 mask)
 {
+	if (atomic_long_read(&inode->i_sb->s_fsnotify_connectors) == 0)
+		return;
+
 	if (S_ISDIR(inode->i_mode))
 		mask |= FS_ISDIR;
 
@@ -53,6 +59,9 @@ static inline int fsnotify_parent(struct dentry *dentry, __u32 mask,
 {
 	struct inode *inode = d_inode(dentry);
 
+	if (atomic_long_read(&inode->i_sb->s_fsnotify_connectors) == 0)
+		return 0;
+
 	if (S_ISDIR(inode->i_mode)) {
 		mask |= FS_ISDIR;