Patch "fsnotify: count s_fsnotify_inode_refs for attached connectors" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    fsnotify: count s_fsnotify_inode_refs for attached connectors

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     fsnotify-count-s_fsnotify_inode_refs-for-attached-co.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 7aa0e01dffa843ebb1e01bc5f990242bae452686
Author: Amir Goldstein <amir73il@xxxxxxxxx>
Date:   Tue Aug 10 18:12:18 2021 +0300

    fsnotify: count s_fsnotify_inode_refs for attached connectors
    
    [ Upstream 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@xxxxxxxxx
    Reviewed-by: Matthew Bobrowski <repnop@xxxxxxxxxx>
    Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
    Signed-off-by: Jan Kara <jack@xxxxxxx>
    Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 3c8fc77d3f072..f6d1ad3ecca2a 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);
 	}