From 182e67bdaac446ed7cb9fa926b930ebafb38ed49 Mon Sep 17 00:00:00 2001

From: Amir Goldstein <amir73il@gmail.com>

Date: Tue, 10 Aug 2021 18:12:19 +0300

Subject: [PATCH] fsnotify: count all objects with attached connectors

References: bsc#1190120 (Fsnotify functional and performance backports)

Patch-mainline: v5.15-rc1

Git-commit: ec44610fe2b86daef70f3f53f47d2a2542d7094f

Rename s_fsnotify_inode_refs to s_fsnotify_connectors and count all

objects with attached connectors, not only inodes with attached

connectors.

This will be used to optimize fsnotify() calls on sb without any

type of marks.

Link: https://lore.kernel.org/r/20210810151220.285179-4-amir73il@gmail.com

Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Reviewed-by: Matthew Bobrowski <repnop@google.com>

Signed-off-by: Jan Kara <jack@suse.cz>

Signed-off-by: Mel Gorman <mgorman@suse.de>

---

 fs/notify/fsnotify.c |  6 +++---

 fs/notify/fsnotify.h | 15 +++++++++++++++

 fs/notify/mark.c     | 24 +++++++++++++++++++++---

 include/linux/fs.h   |  7 +++++--

 4 files changed, 44 insertions(+), 8 deletions(-)

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c

index 30d422b8c0fc..963e6ce75b96 100644

--- a/fs/notify/fsnotify.c

+++ b/fs/notify/fsnotify.c

@@ -87,15 +87,15 @@ static void fsnotify_unmount_inodes(struct super_block *sb)

 	if (iput_inode)

 		iput(iput_inode);

-	/* Wait for outstanding inode references from connectors */

-	wait_var_event(&sb->s_fsnotify_inode_refs,

-		       !atomic_long_read(&sb->s_fsnotify_inode_refs));

 }

 void fsnotify_sb_delete(struct super_block *sb)

 {

 	fsnotify_unmount_inodes(sb);

 	fsnotify_clear_marks_by_sb(sb);

+	/* Wait for outstanding object references from connectors */

+	wait_var_event(&sb->s_fsnotify_connectors,

+		       !atomic_long_read(&sb->s_fsnotify_connectors));

 }

 /*

diff --git a/fs/notify/fsnotify.h b/fs/notify/fsnotify.h

index ff2063ec6b0f..87d8a50ee803 100644

--- a/fs/notify/fsnotify.h

+++ b/fs/notify/fsnotify.h

@@ -27,6 +27,21 @@ static inline struct super_block *fsnotify_conn_sb(

 	return container_of(conn->obj, struct super_block, s_fsnotify_marks);

 }

+static inline struct super_block *fsnotify_connector_sb(

+				struct fsnotify_mark_connector *conn)

+{

+	switch (conn->type) {

+	case FSNOTIFY_OBJ_TYPE_INODE:

+		return fsnotify_conn_inode(conn)->i_sb;

+	case FSNOTIFY_OBJ_TYPE_VFSMOUNT:

+		return fsnotify_conn_mount(conn)->mnt.mnt_sb;

+	case FSNOTIFY_OBJ_TYPE_SB:

+		return fsnotify_conn_sb(conn);

+	default:

+		return NULL;

+	}

+}

+

 /* destroy all events sitting in this groups notification queue */

 extern void fsnotify_flush_notify(struct fsnotify_group *group);

diff --git a/fs/notify/mark.c b/fs/notify/mark.c

index 2d8c46e1167d..95006d1d29ab 100644

--- a/fs/notify/mark.c

+++ b/fs/notify/mark.c

@@ -172,7 +172,7 @@ 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);

+	atomic_long_inc(&inode->i_sb->s_fsnotify_connectors);

 }

 static void fsnotify_put_inode_ref(struct inode *inode)

@@ -180,8 +180,24 @@ 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);

+	if (atomic_long_dec_and_test(&sb->s_fsnotify_connectors))

+		wake_up_var(&sb->s_fsnotify_connectors);

+}

+

+static void fsnotify_get_sb_connectors(struct fsnotify_mark_connector *conn)

+{

+	struct super_block *sb = fsnotify_connector_sb(conn);

+

+	if (sb)

+		atomic_long_inc(&sb->s_fsnotify_connectors);

+}

+

+static void fsnotify_put_sb_connectors(struct fsnotify_mark_connector *conn)

+{

+	struct super_block *sb = fsnotify_connector_sb(conn);

+

+	if (sb && atomic_long_dec_and_test(&sb->s_fsnotify_connectors))

+		wake_up_var(&sb->s_fsnotify_connectors);

 }

 static void *fsnotify_detach_connector_from_object(

@@ -203,6 +219,7 @@ static void *fsnotify_detach_connector_from_object(

 		fsnotify_conn_sb(conn)->s_fsnotify_mask = 0;

 	}

+	fsnotify_put_sb_connectors(conn);

 	rcu_assign_pointer(*(conn->obj), NULL);

 	conn->obj = NULL;

 	conn->type = FSNOTIFY_OBJ_TYPE_DETACHED;

@@ -504,6 +521,7 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp,

 		inode = fsnotify_conn_inode(conn);

 		fsnotify_get_inode_ref(inode);

 	}

+	fsnotify_get_sb_connectors(conn);

 	/*

 	 * cmpxchg() provides the barrier so that readers of *connp can see

diff --git a/include/linux/fs.h b/include/linux/fs.h

index b2341c262f78..4d747acf9453 100644

--- a/include/linux/fs.h

+++ b/include/linux/fs.h

@@ -1516,8 +1516,11 @@ struct super_block {

 	/* Number of inodes with nlink == 0 but still referenced */

 	atomic_long_t s_remove_count;

-	/* Pending fsnotify inode refs */

-	atomic_long_t s_fsnotify_inode_refs;

+	/*

+	 * Number of inode/mount/sb objects that are being watched, note that

+	 * inodes objects are currently double-accounted.

+	 */

+	atomic_long_t s_fsnotify_connectors;

 	/* Being remounted read-only */

 	int s_readonly_remount;