fsnotify: replace inode pointer with an object id

The event inode field is used only for comparison in queue merges and
cannot be dereferenced after handle_event(), because it does not hold a
refcount on the inode.

Replace it with an abstract id to do the same thing.

Link: https://lore.kernel.org/r/20200319151022.31456-8-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 19ec7a4..6a202aa 100644 (file)
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -26,7 +26,7 @@ static bool should_merge(struct fsnotify_event *old_fsn,
        old = FANOTIFY_E(old_fsn);
        new = FANOTIFY_E(new_fsn);
 
-       if (old_fsn->inode != new_fsn->inode || old->pid != new->pid ||
+       if (old_fsn->objectid != new_fsn->objectid || old->pid != new->pid ||
            old->fh_type != new->fh_type || old->fh_len != new->fh_len)
                return false;
 
@@ -312,7 +312,7 @@ struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
        if (!event)
                goto out;
 init: __maybe_unused
-       fsnotify_init_event(&event->fse, inode);
+       fsnotify_init_event(&event->fse, (unsigned long)inode);
        event->mask = mask;
        if (FAN_GROUP_FLAG(group, FAN_REPORT_TID))
                event->pid = get_pid(task_pid(current));

diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
index 6bb9852..2ebc890 100644 (file)
--- a/fs/notify/inotify/inotify_fsnotify.c
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -39,7 +39,7 @@ static bool event_compare(struct fsnotify_event *old_fsn,
        if (old->mask & FS_IN_IGNORED)
                return false;
        if ((old->mask == new->mask) &&
-           (old_fsn->inode == new_fsn->inode) &&
+           (old_fsn->objectid == new_fsn->objectid) &&
            (old->name_len == new->name_len) &&
            (!old->name_len || !strcmp(old->name, new->name)))
                return true;
@@ -116,7 +116,7 @@ int inotify_handle_event(struct fsnotify_group *group,
                mask &= ~IN_ISDIR;
 
        fsn_event = &event->fse;
-       fsnotify_init_event(fsn_event, inode);
+       fsnotify_init_event(fsn_event, (unsigned long)inode);
        event->mask = mask;
        event->wd = i_mark->wd;
        event->sync_cookie = cookie;

diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 107537a..81ffc86 100644 (file)
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -635,7 +635,7 @@ static struct fsnotify_group *inotify_new_group(unsigned int max_events)
                return ERR_PTR(-ENOMEM);
        }
        group->overflow_event = &oevent->fse;
-       fsnotify_init_event(group->overflow_event, NULL);
+       fsnotify_init_event(group->overflow_event, 0);
        oevent->mask = FS_Q_OVERFLOW;
        oevent->wd = -1;
        oevent->sync_cookie = 0;

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 337c87c..c72cbea 100644 (file)
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -132,8 +132,7 @@ struct fsnotify_ops {
  */
 struct fsnotify_event {
        struct list_head list;
-       /* inode may ONLY be dereferenced during handle_event(). */
-       struct inode *inode;    /* either the inode the event happened to or its parent */
+       unsigned long objectid; /* identifier for queue merges */
 };
 
 /*
@@ -526,10 +525,10 @@ extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info);
 extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info);
 
 static inline void fsnotify_init_event(struct fsnotify_event *event,
-                                      struct inode *inode)
+                                      unsigned long objectid)
 {
        INIT_LIST_HEAD(&event->list);
-       event->inode = inode;
+       event->objectid = objectid;
 }
 
 #else