On Fri, Apr 9, 2021 at 1:08 PM Jan Kara <jack@xxxxxxx> wrote: > > On Thu 08-04-21 18:11:31, Amir Goldstein wrote: > > > > FYI, I tried your suggested approach above for fsnotify_xattr(), > > > > but I think I prefer to use an explicit flavor fsnotify_xattr_mnt() > > > > and a wrapper fsnotify_xattr(). > > > > Pushed WIP to fsnotify_path_hooks branch. It also contains > > > > some unstashed "fix" patches to tidy up the previous hooks. > > > > > > What's in fsnotify_path_hooks branch looks good to me wrt xattr hooks. > > > I somewhat dislike about e.g. the fsnotify_create() approach you took is > > > that there are separate hooks fsnotify_create() and fsnotify_create_path() > > > which expose what is IMO an internal fsnotify detail of what are different > > > event types. I'd say it is more natural (from VFS POV) to have just a > > > single hook and fill in as much information as available... Also from > > > > So to be clear, you do NOT want additional wrappers like this and > > you prefer to have the NULL mnt argument explicit in all callers? > > > > static inline void fsnotify_xattr(struct dentry *dentry) > > { > > fsnotify_xattr_mnt(NULL, dentry); > > } > > > > For fsnotify_xattr() it does not matter so much, but fsnotify_create/mkdir() > > have quite a few callers in special filesystems. > > Yes, I prefer explicit NULL mnt argument to make it obvious we are going to > miss something in this case. I agree it's going to be somewhat bigger churn > but it isn't that bad (10 + 6 callers). > > > > outside view, it is unclear that e.g. vfs_create() will generate some types > > > of fsnotify events but not all while e.g. do_mknodat() will generate all > > > fsnotify events. That's why I'm not sure whether a helper like vfs_create() > > > in your tree is the right abstraction since generating one type of fsnotify > > > event while not generating another type should be a very conscious decision > > > of the implementor - basically if you have no other option. > > > > I lost you here. > > Sorry, I was probably too philosophical here ;) > > > Are you ok with vfs_create() vs. vfs_create_nonotify()? > > I'm OK with vfs_create_nonotify(). I have a problem with vfs_create() > because it generates inode + fs events but does not generate mount events > which is just strange (although I appreciate the technical reason behind > it :). > > > How do you propose to change fsnotify hooks in vfs_create()? > > So either pass 'mnt' to vfs_create() - as we discussed, this may be > actually acceptable these days due to idmapped mounts work - and generate > all events there, or make vfs_create() not generate any fsnotify events and > create new vfs_create_notify() which will take the 'mnt' and generate > events. Either is fine with me and more consistent than what you currently > propose. Thoughts? > Jan, I started to go down the vfs_create_notify() path and I guess it's looking not too bad (?). Pushed WIP to branch fsnotify_path_hooks-wip. I hit another bump though. By getting fsnotify_{unlink,rmdir}() outside of the vfs helpers, we break the rule: /* Expected to be called before d_delete() */ WARN_ON_ONCE(d_is_negative(dentry)); I'm not sure how to solve this without passing mnt into the vfs helpers. One solution is not adding support for delete events to mount mark. I was trying to aim for maximum flexibility, but for the use case that Christian mentioned (injecting bind mounts into container) it is only really necessary to support FAN_CREATE and FAN_MOVED_TO (or FAN_MOVE_SELF) on a mount mark for observing when a path becomes positive. For observing when a path becomes negative, it is sufficient to watch all the ancestor directories. Thoughts? Thanks, Amir.