A file is opened for read-only, opened read-write (resulting in a copy up) and modified. The data read back from the the read-only fd will be stale in this case (the read-only file descriptor still refers to the lower, unmodified file).
This patchset fixes issues related to this corner case. The VFS impact is minimal and performance in the non-corner cases shouldn't suffer. --- Miklos Szeredi (7): vfs: allow overlayfs to intercept file ops vfs: export filp_clone_open() mm: ovl: copy-up on MAP_SHARED ovl: add infrastructure for intercepting file ops ovl: intercept read_iter ovl: intercept mmap ovl: intercept fsync fs/internal.h | 1 - fs/open.c | 2 +- fs/overlayfs/inode.c | 225 +++++++++++++++++++++++++++++++++++++++++++++++ fs/overlayfs/overlayfs.h | 2 + fs/overlayfs/super.c | 1 + include/linux/fs.h | 1 + mm/util.c | 22 +++++ 7 files changed, 252 insertions(+), 2 deletions(-) -- 2.5.5
