Jörn Engel wrote: > Apart from the typo above, here is a more discouraging version: > > In general, accessing the block device directly is strongly discouraged. > Exceptions exist mainly in the form of boot loaders like lilo and grub, > at a time when the filesystem is not (cannot be) mounted. > > If the flag DATA_ENCODED is set, however, even this exception is no > longer valid. The content is encoded in some form. Details are > unknown, it could be compressed, encrypted or something else. I'm not clear about something from the above description. If I were writing a journalling / tree-like filesystem, and I did store data in blocks without encoding, but fsync() only waits for them to be committed to journal, not their final destination, and also they might be moved around - should I set DATA_ENCODED or not? (And should I return the temporary location in the long-running journal since that's the only place the data is committed at the time of the call?) Assume that even reading after unmounting is not 100% safe, because the data blocks could be relocated after calling FIEMAP (when the filesystem must be mounted), and before the unmount. -- Jamie -- 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
