fsnotify: count s_fsnotify_inode_refs for attached connectors

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>

diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 80459db..2d8c46e 100644 (file)
--- 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);
        }