[RFC,0/3] ovl: stacked mmap for shared map

Message

Chengguang Xu Aug. 29, 2020, 9:50 a.m. UTC

Currently, there is still ro/rw inconsistency related to shared mmap
in overlayfs, this patch set implements stacked mmap for shared map
and transfer necessary operations to upper inode, so that we can keep
data consistency in any kind of mmap. 

Patch 1 exports necessary functions from kernel to module.
Patch 2 introduces struct ovl_file_entry to store real vm_ops.
Patch 3 implements stacked mmap for shared map to keep data
consistency.

Chengguang Xu (3):
  mm: mmap: export necessary functions for overlayfs' mmap
  ovl: introduce struct ovl_file_entry
  ovl: implement stacked mmap for shared map

 fs/overlayfs/file.c | 178 ++++++++++++++++++++++++++++++++++++++++----
 include/linux/mm.h  |   2 +
 mm/filemap.c        |  28 +++++++
 mm/internal.h       |  22 ------
 4 files changed, 195 insertions(+), 35 deletions(-)