fsnotify: clean up fsnotify()

Use helpers to get first and next marks from connector.

Also get rid of inode_node/vfsmount_node local variables, which just refers
to the same objects as iter_info.  There was an srcu_dereference() for
foo_node, but that's completely superfluous since we've already done it
when obtaining foo_node.

Also get rid of inode_group/vfsmount_group local variables; checking
against non-NULL for these is the same as checking against non-NULL
inode_mark/vfsmount_mark.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 45 insertions, 60 deletions

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 074716293829..81d8959b6aef 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -243,6 +243,29 @@ static int send_to_group(struct inode *to_tell,
                                         file_name, cookie, iter_info);
 }
 
+static struct fsnotify_mark *fsnotify_first_mark(struct fsnotify_mark_connector **connp)
+{
+        struct fsnotify_mark_connector *conn;
+        struct hlist_node *node = NULL;
+
+        conn = srcu_dereference(*connp, &fsnotify_mark_srcu);
+        if (conn)
+                node = srcu_dereference(conn->list.first, &fsnotify_mark_srcu);
+
+        return hlist_entry_safe(node, struct fsnotify_mark, obj_list);
+}
+
+static struct fsnotify_mark *fsnotify_next_mark(struct fsnotify_mark *mark)
+{
+        struct hlist_node *node = NULL;
+
+        if (mark)
+                node = srcu_dereference(mark->obj_list.next,
+                                        &fsnotify_mark_srcu);
+
+        return hlist_entry_safe(node, struct fsnotify_mark, obj_list);
+}
+
 /*
  * This is the main call to fsnotify.  The VFS calls into hook specific functions
  * in linux/fsnotify.h.  Those functions then in turn call here.  Here will call
@@ -252,11 +275,7 @@ static int send_to_group(struct inode *to_tell,
 int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
              const unsigned char *file_name, u32 cookie)
 {
-        struct hlist_node *inode_node = NULL, *vfsmount_node = NULL;
-        struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL;
-        struct fsnotify_group *inode_group, *vfsmount_group;
-        struct fsnotify_mark_connector *inode_conn, *vfsmount_conn;
-        struct fsnotify_iter_info iter_info;
+        struct fsnotify_iter_info iter_info = {};
         struct mount *mnt;
         int ret = 0;
         /* global tests shouldn't care about events on child only the specific event */
@@ -291,26 +310,16 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
 
         if ((mask & FS_MODIFY) ||
             (test_mask & to_tell->i_fsnotify_mask)) {
-                inode_conn = srcu_dereference(to_tell->i_fsnotify_marks,
-                                              &fsnotify_mark_srcu);
-                if (inode_conn)
-                        inode_node = srcu_dereference(inode_conn->list.first,
-                                                      &fsnotify_mark_srcu);
+                iter_info.inode_mark =
+                        fsnotify_first_mark(&to_tell->i_fsnotify_marks);
         }
 
         if (mnt && ((mask & FS_MODIFY) ||
                     (test_mask & mnt->mnt_fsnotify_mask))) {
-                inode_conn = srcu_dereference(to_tell->i_fsnotify_marks,
-                                              &fsnotify_mark_srcu);
-                if (inode_conn)
-                        inode_node = srcu_dereference(inode_conn->list.first,
-                                                      &fsnotify_mark_srcu);
-                vfsmount_conn = srcu_dereference(mnt->mnt_fsnotify_marks,
-                                                 &fsnotify_mark_srcu);
-                if (vfsmount_conn)
-                        vfsmount_node = srcu_dereference(
-                                                vfsmount_conn->list.first,
-                                                &fsnotify_mark_srcu);
+                iter_info.inode_mark =
+                        fsnotify_first_mark(&to_tell->i_fsnotify_marks);
+                iter_info.vfsmount_mark =
+                        fsnotify_first_mark(&mnt->mnt_fsnotify_marks);
         }
 
         /*
@@ -318,41 +327,17 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
          * ignore masks are properly reflected for mount mark notifications.
          * That's why this traversal is so complicated...
          */
-        while (inode_node || vfsmount_node) {
-                inode_group = NULL;
-                inode_mark = NULL;
-                vfsmount_group = NULL;
-                vfsmount_mark = NULL;
-
-                if (inode_node) {
-                        inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu),
-                                                 struct fsnotify_mark, obj_list);
-                        inode_group = inode_mark->group;
-                }
-
-                if (vfsmount_node) {
-                        vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu),
-                                                    struct fsnotify_mark, obj_list);
-                        vfsmount_group = vfsmount_mark->group;
-                }
-                /*
-                 * Need to protect both marks against freeing so that we can
-                 * continue iteration from this place, regardless of which mark
-                 * we actually happen to send an event for.
-                 */
-                iter_info.inode_mark = inode_mark;
-                iter_info.vfsmount_mark = vfsmount_mark;
-
-                if (inode_group && vfsmount_group) {
-                        int cmp = fsnotify_compare_groups(inode_group,
-                                                          vfsmount_group);
-                        if (cmp > 0) {
-                                inode_group = NULL;
+        while (iter_info.inode_mark || iter_info.vfsmount_mark) {
+                struct fsnotify_mark *inode_mark = iter_info.inode_mark;
+                struct fsnotify_mark *vfsmount_mark = iter_info.vfsmount_mark;
+
+                if (inode_mark && vfsmount_mark) {
+                        int cmp = fsnotify_compare_groups(inode_mark->group,
+                                                          vfsmount_mark->group);
+                        if (cmp > 0)
                                 inode_mark = NULL;
-                        } else if (cmp < 0) {
-                                vfsmount_group = NULL;
+                        else if (cmp < 0)
                                 vfsmount_mark = NULL;
-                        }
                 }
 
                 ret = send_to_group(to_tell, inode_mark, vfsmount_mark, mask,
@@ -362,12 +347,12 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
                 if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
                         goto out;
 
-                if (inode_group)
-                        inode_node = srcu_dereference(inode_node->next,
-                                                      &fsnotify_mark_srcu);
-                if (vfsmount_group)
-                        vfsmount_node = srcu_dereference(vfsmount_node->next,
-                                                         &fsnotify_mark_srcu);
+                if (inode_mark)
+                        iter_info.inode_mark =
+                                fsnotify_next_mark(iter_info.inode_mark);
+                if (vfsmount_mark)
+                        iter_info.vfsmount_mark =
+                                fsnotify_next_mark(iter_info.vfsmount_mark);
         }
         ret = 0;
 out: