On Wed, Oct 02, 2013 at 01:24:25PM +0200, David Herrmann wrote: > DRM core shares a single address_space across all inodes that belong to > the same DRM device. This allows efficient unmapping of user-space > mappings during buffer eviction. However, there is no easy way to get a > shared address_space for DRM devices during initialization. Therefore, we > currently delay this step until the first ->open() and save the given > inode for future use. > > This causes ugly delayed initialization throughout the DRM core. TTM > devices end up without a dev_mapping pointer and we have to carefully > respect any underlying filesystem implementation so we don't corrupt the > inode->i_mapping and inode->i_data fields. > > We can avoid this if we were allowed to allocate an anonymous inode for > each DRM device. We only have to set file->f_mapping during ->open() > and no longer need to adjust inode mappings. As fs/anon_inodes.c already > provides a minimal internal FS mount, we extend it to also provide > anonymous inodes for use in drivers like DRM. > > Signed-off-by: David Herrmann <dh.herrmann@xxxxxxxxx> > Wanted-by: Daniel Vetter <daniel.vetter@xxxxxxxx> Told-to-stop-abusing-anon_inodes-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Note that anon_inode_getfile_private() is not going to survive - for exact same reasons. It's already removed in vfs.git#experimental, shortly in #for-next as well. Do NOT extend fs/anon_inodes.c; if you need a minimal internal fs mount, just do what fs/aio.c does in the same branch. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
