From b766fc83fccdab67c1cbe5fce969394ae94c686c Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Tue, 10 Aug 2021 18:12:18 +0300
Subject: [PATCH] fsnotify: count s_fsnotify_inode_refs for attached connectors

References: bsc#1190120 (Fsnotify functional and performance backports)
Patch-mainline: v5.15-rc1
Git-commit: 11fa333b58ba1518e7c69fafb6513a0117f8fe33

Instead of incrementing s_fsnotify_inode_refs when detaching connector
from inode, increment it earlier when attaching connector to inode.
Next patch is going to use s_fsnotify_inode_refs to count all objects
with attached connectors.

Link: https://lore.kernel.org/r/20210810151220.285179-3-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>
---
 fs/notify/mark.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 80459db58f63..2d8c46e1167d 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -169,6 +169,21 @@ static void fsnotify_connector_destroy_workfn(struct work_struct *work)
 	}
 }
 
+static void fsnotify_get_inode_ref(struct inode *inode)
+{
+	ihold(inode);
+	atomic_long_inc(&inode->i_sb->s_fsnotify_inode_refs);
+}
+
+static void fsnotify_put_inode_ref(struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+
+	iput(inode);
+	if (atomic_long_dec_and_test(&sb->s_fsnotify_inode_refs))
+		wake_up_var(&sb->s_fsnotify_inode_refs);
+}
+
 static void *fsnotify_detach_connector_from_object(
 					struct fsnotify_mark_connector *conn,
 					unsigned int *type)
@@ -182,7 +197,6 @@ static void *fsnotify_detach_connector_from_object(
 	if (conn->type == FSNOTIFY_OBJ_TYPE_INODE) {
 		inode = fsnotify_conn_inode(conn);
 		inode->i_fsnotify_mask = 0;
-		atomic_long_inc(&inode->i_sb->s_fsnotify_inode_refs);
 	} else if (conn->type == FSNOTIFY_OBJ_TYPE_VFSMOUNT) {
 		fsnotify_conn_mount(conn)->mnt_fsnotify_mask = 0;
 	} else if (conn->type == FSNOTIFY_OBJ_TYPE_SB) {
@@ -209,19 +223,12 @@ static void fsnotify_final_mark_destroy(struct fsnotify_mark *mark)
 /* Drop object reference originally held by a connector */
 static void fsnotify_drop_object(unsigned int type, void *objp)
 {
-	struct inode *inode;
-	struct super_block *sb;
-
 	if (!objp)
 		return;
 	/* Currently only inode references are passed to be dropped */
 	if (WARN_ON_ONCE(type != FSNOTIFY_OBJ_TYPE_INODE))
 		return;
-	inode = objp;
-	sb = inode->i_sb;
-	iput(inode);
-	if (atomic_long_dec_and_test(&sb->s_fsnotify_inode_refs))
-		wake_up_var(&sb->s_fsnotify_inode_refs);
+	fsnotify_put_inode_ref(objp);
 }
 
 void fsnotify_put_mark(struct fsnotify_mark *mark)
@@ -495,7 +502,7 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp,
 	}
 	if (conn->type == FSNOTIFY_OBJ_TYPE_INODE) {
 		inode = fsnotify_conn_inode(conn);
-		ihold(inode);
+		fsnotify_get_inode_ref(inode);
 	}
 
 	/*
@@ -505,7 +512,7 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp,
 	if (cmpxchg(connp, NULL, conn)) {
 		/* Someone else created list structure for us */
 		if (inode)
-			iput(inode);
+			fsnotify_put_inode_ref(inode);
 		kmem_cache_free(fsnotify_mark_connector_cachep, conn);
 	}