> >> What happens if the application overwrites what it had written some > >> time later? Nothing. The page is already read-write, the pte dirty, > >> so even though the file was clearly modified, there's absolutely no > >> way in which this can be used to force an update to the timestamp. > >> > > > > Which, I realize now, actually means, that the patch is wrong. Msync > > will have to write protect the page table entries, so that later > > dirtyings may have an effect on the timestamp. > > I thought that PeterZ's changes were to write-protect the page after > cleaning it so that future modifications could be detected and tracked > accordingly? Does the right thing not happen already? Yes, but MS_ASYNC does not clean the pages. In fact a better solution may be to rely on the dirty bit in the page tables, so that no more page faults are necessary. Thanks, Miklos - 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
