On Mon, Dec 08, 2014 at 03:47:23PM +0100, Martin Steigerwald wrote: > Am Sonntag, 7. Dezember 2014, 21:32:01 schrieb Robert White: > > On 12/07/2014 07:40 AM, Martin Steigerwald wrote: > > Almost full filesystems are their own reward. > > So you basically say that BTRFS with compression does not meet the fallocate > guarantee. Now thats interesting, cause it basically violates the > documentation for the system call: > > DESCRIPTION > The function posix_fallocate() ensures that disk space is allo‐ > cated for the file referred to by the descriptor fd for the bytes > in the range starting at offset and continuing for len bytes. > After a successful call to posix_fallocate(), subsequent writes > to bytes in the specified range are guaranteed not to fail > because of lack of disk space. > > So in order to be standard compliant there, BTRFS would need to write > fallocated files uncompressed… wow this is getting complex. ...and nodatacow and no snapshots, since those require more space that was never anticipated by fallocate. Given the choice, I'd just let fallocate fail. Usually when I come across a program using fallocate, I end up patching it so it doesn't use fallocate any more. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
