Michael Tokarev <[EMAIL PROTECTED]> wrote: > I wonder why open() with O_DIRECT (for example) bit set is > disallowed on a tmpfs (again, for example) filesystem, > returning EINVAL. > > Yes, the question may seems strange a bit, because of two > somewhat conflicting reasons. First, there's no reason to > use O_DIRECT with tmpfs in a first place, because tmpfs does > not have backing store at all, so there's no place to do > direct writes to. But on another hand, again due to the very > nature of tmpfs, there's no reason not to allow O_DIRECT > open and just ignore it, -- exactly because there's no > backing store for this filesystem.
I'm using a tmpfs as a mostly-ramdisk, that is I've set up a large swap partition in case I need the RAM instead of using it for a filesystem. Therefore it will sometimes have a backing store. OTOH, ramfs does not have this property (the cache is the backing store), so it would make sense to allow it at least there. BTW: Maybe you could use a ramdisk instead of the loop-on-tmpfs. -- Ich danke GMX dafür, die Verwendung meiner Adressen mittels per SPF verbreiteten Lügen zu sabotieren. http://david.woodhou.se/why-not-spf.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/