On Mon, Jun 11, 2018 at 4:36 PM, Jan Kara <jack@xxxxxxx> wrote: > > On Sun 10-06-18 20:49:16, Amir Goldstein wrote: > > On Sat, Jun 9, 2018 at 9:46 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote: > > > On Sat, Jun 9, 2018 at 8:30 PM, Linus Torvalds > > > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > >> On Fri, Jun 8, 2018 at 11:57 PM Amir Goldstein <amir73il@xxxxxxxxx> wrote: > > >>> > > >>> We embed fsnotify_obj in struct inode and fsnotify_obj_mask in struct mount. > > >> > > >> So I'd *really* like to see just a pointer, not an embedded struct. > > >> > > >> Yes, if you get rid of the mask from the embedded struct (so that it > > >> only contains a pointer), you do get rid of the odd alignment issues > > >> and the need for "packed". > > >> > > >> But from previous experience, once you embed a structure, that > > >> structure tends to grow. Because it can, and it's so convenient. > > >> Suddently it has a spinlock in it too etc. > > >> > > > > > > Fair enough. > > > > > >> So if you can make do with just the pointer, it would actually be > > >> nicer to expose it as such. Then you can also avoid the header file > > >> dependency chain, because you can just pre-declare the structure (like > > >> it does now) and > > >> > > >> struct fsnotify_mark_connector; > > >> .. > > >> struct fsnotify_mark_connector __rcu *i_fsnotify_marks; > > >> > > >> in the inode. That way the core header files don't need to worry about > > >> the fsnotify details, and don't need to include fsnotify headers. > > >> > > >> And we can do inode packing without having to know (not that it > > >> happens all that often - everybody would *love* to shrink the inode > > >> structure, but it's just hard. Because everybody also wants to put > > >> their own data into the inode ..) > > >> > > >> Can't the generalization code just take a pointer to a __rcu pointer > > >> to fsnotify_mark_connector, obviating the need for the fsnotify_obj > > >> structure definition? > > >> > > > > > > > Jan, > > > > I reworked the cleanup patches to get rid of fsnotify_obj and pushed to: > > https://github.com/amir73il/linux.git fsnotify-cleanup > > Thanks! > > > Only last 5 patches from fsnotify_for_v4.18-rc1 have been modified > > and I removed your S-O-B from the modified patches. > > > > This leaves struct inode unchanged, in fact no changes to code outside > > fsnotify/audit at all. > > > > mask is now a member of connector for the purpose of generalizing > > add/remove mark, but struct inode/mount still have a copy of the mask > > for the purpose of the VFS optimizations. > > Looking through those patches, is it really beneficial to add mask to > connector when you keep it in inode / vfsmount? A helper function to get > mask from connector would make the same refactoring possible as well, won't > it? > > And adding a helper function to set mask given connector would get rid of > the remaining checks for connector type due to mask manipulations... > By moving the checks for object type into the helper? Maybe I am missing your point. Anyway, my thinking was: What do we have to loose from keeping the mask also inside the connector? Not much. We didn't change the size of connector struct and it hardly adds any complexity / performance cost. What do we have to gain from keeping the mask also inside the connector? We can later get rid of the copy of mask in inode struct as I wrote. I will follow up on that. Thanks, Amir.
