Instead of counting the number of connectors in an sb, we would like
to count the number of watched objects per priority group.
As a start, create an accessor fsnotify_sb_watched_objects() to
s_fsnotify_connectors and rename the fsnotify_{get,put}_sb_connectors()
helpers to fsnotify_{get,put}_sb_watchers() to better describes the
counter.
Increment the counter at the end of fsnotify_attach_connector_to_object()
if connector was attached instead of decrementing it on race to connect.
This is fine, because fsnotify_delete_sb() cannot be running in parallel
to fsnotify_attach_connector_to_object() which requires a reference to
a filesystem object.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/notify/fsnotify.c | 4 +-
fs/notify/mark.c | 67 ++++++++++++++++++--------------
include/linux/fsnotify.h | 2 +-
include/linux/fsnotify_backend.h | 5 +++
4 files changed, 45 insertions(+), 33 deletions(-)
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 2fc105a72a8f..503e7c75e777 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -92,8 +92,8 @@ 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));
+ wait_var_event(fsnotify_sb_watched_objects(sb),
+ !atomic_long_read(fsnotify_sb_watched_objects(sb)));
}
/*
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index d6944ff86ffa..8339d77b1aa2 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -116,10 +116,43 @@ __u32 fsnotify_conn_mask(struct fsnotify_mark_connector *conn)
return *fsnotify_conn_mask_p(conn);
}
+static void fsnotify_get_sb_watched_objects(struct super_block *sb)
+{
+ atomic_long_inc(fsnotify_sb_watched_objects(sb));
+}
+
+static void fsnotify_put_sb_watched_objects(struct super_block *sb)
+{
+ if (atomic_long_dec_and_test(fsnotify_sb_watched_objects(sb)))
+ wake_up_var(fsnotify_sb_watched_objects(sb));
+}
+
static void fsnotify_get_inode_ref(struct inode *inode)
{
ihold(inode);
- atomic_long_inc(&inode->i_sb->s_fsnotify_connectors);
+ fsnotify_get_sb_watched_objects(inode->i_sb);
+}
+
+static void fsnotify_put_inode_ref(struct inode *inode)
+{
+ iput(inode);
+ fsnotify_put_sb_watched_objects(inode->i_sb);
+}
+
+static void fsnotify_get_sb_watchers(struct fsnotify_mark_connector *conn)
+{
+ struct super_block *sb = fsnotify_connector_sb(conn);
+
+ if (sb)
+ fsnotify_get_sb_watched_objects(sb);
+}
+
+static void fsnotify_put_sb_watchers(struct fsnotify_mark_connector *conn)
+{
+ struct super_block *sb = fsnotify_connector_sb(conn);
+
+ if (sb)
+ fsnotify_put_sb_watched_objects(sb);
}
/*
@@ -213,31 +246,6 @@ static void fsnotify_connector_destroy_workfn(struct work_struct *work)
}
}
-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_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(
struct fsnotify_mark_connector *conn,
unsigned int *type)
@@ -261,7 +269,7 @@ static void *fsnotify_detach_connector_from_object(
fsnotify_conn_sb(conn)->s_fsnotify_mask = 0;
}
- fsnotify_put_sb_connectors(conn);
+ fsnotify_put_sb_watchers(conn);
rcu_assign_pointer(*(conn->obj), NULL);
conn->obj = NULL;
conn->type = FSNOTIFY_OBJ_TYPE_DETACHED;
@@ -549,8 +557,6 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp,
conn->flags = 0;
conn->type = obj_type;
conn->obj = connp;
- conn->flags = 0;
- fsnotify_get_sb_connectors(conn);
/*
* cmpxchg() provides the barrier so that readers of *connp can see
@@ -558,10 +564,11 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp,
*/
if (cmpxchg(connp, NULL, conn)) {
/* Someone else created list structure for us */
- fsnotify_put_sb_connectors(conn);
kmem_cache_free(fsnotify_mark_connector_cachep, conn);
+ return 0;
}
+ fsnotify_get_sb_watchers(conn);
return 0;
}
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 1a9de119a0f7..e470bb67c9a3 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -20,7 +20,7 @@
/* Are there any inode/mount/sb objects that are being watched at all? */
static inline bool fsnotify_sb_has_watchers(struct super_block *sb)
{
- return atomic_long_read(&sb->s_fsnotify_connectors);
+ return atomic_long_read(fsnotify_sb_watched_objects(sb));
}
/*
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 8f40c349b228..d4e3bc55d174 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -483,6 +483,11 @@ struct fsnotify_mark_connector {
struct hlist_head list;
};
+static inline atomic_long_t *fsnotify_sb_watched_objects(struct super_block *sb)
+{
+ return &sb->s_fsnotify_connectors;
+}
+
/*
* A mark is simply an object attached to an in core inode which allows an
* fsnotify listener to indicate they are either no longer interested in events
--
2.34.1
