On Wed, Apr 12, 2023 at 10:29:37PM +0900, Tetsuo Handa wrote: > On 2023/04/12 22:13, Matthew Wilcox wrote: > >> Also, since Documentation/filesystems/fiemap.rst says that "If an error > >> is encountered while copying the extent to user memory, -EFAULT will be > >> returned.", I assume that ioctl(FS_IOC_FIEMAP) users can handle -EFAULT > >> error. > > > > What? No, that doesn't mean "You can return -EFAULT because random luck". > > That means "If you pass it an invalid address, you'll get -EFAULT back". > > > > NACK. > > Then, why does fiemap.rst say "If an error is encountered" rather than > "If an invalid address is passed" ? Because people are bad at writing. > Does the definition of -EFAULT limited to "the caller does not have permission > to access this address" ? Or the address isn't mapped. > If copy_to_user() must not fail other than "the caller does not have > permission to access this address", what should we do for now? > Just remove ntfs_fiemap() and return -EOPNOTSUPP ? No, fix it properly. Or don't fix it at all and let somebody else fix it.
