On Thu, 19 Oct 2023 at 16:33, Amir Goldstein <amir73il@xxxxxxxxx> wrote: > generic/120 tests -o noatime and fails because atime is > updated (on the backing file). > This is a general FUSE issue and passthrough_hp --nocache fails > the same test (i.e. it only passed because of attribute cache). > > generic/080, generic/215 both test for c/mtime updates after mapped writes. > It is not surprising that backing file passthrough fails these tests - > there is no "passthrough getattr" like overlayfs and there is no opportunity > to invalidate the FUSE inode attribute cache. This is what POSIX has to say: "The last data modification and last file status change timestamps of a file that is mapped with MAP_SHARED and PROT_WRITE shall be marked for update at some point in the interval between a write reference to the mapped region and the next call to msync() with MS_ASYNC or MS_SYNC for that portion of the file by any process. If there is no such call and if the underlying file is modified as a result of a write reference, then these timestamps shall be marked for update at some time after the write reference." Not sure if the test is doing msync(), but invalidating cached c/mtime on msync() shouldn't be too hard (msync -> fsync). While the standard doesn't seem to require updating c/mtime on mumap(2) if there was a modification, that might also make sense in practice. Thanks, Miklos
