On Thu, Jan 16, 2020 at 11:29:20AM +0000, fdmanana@xxxxxxxxxx wrote: > From: Filipe Manana <fdmanana@xxxxxxxx> > > If scrub returns an error we are not copying back the scrub arguments > structure to user space. This prevents user space to know how much progress > scrub has done if an error happened - this includes -ECANCELED which is > returned when users ask for scrub to stop. A particular use case, which is > used in btrfs-progs, is to resume scrub after it is canceled, in that case > it relies on checking the progress from the scrub arguments structure and > then use that progress in a call to resume scrub. > > So fix this by always copying the scrub arguments structure to user space, > overwriting the value returned to user space with -EFAULT only if copying > the structure failed to let user space know that either that copying did > not happen, and therefore the structure is stale, or it happened partially > and the structure is probably not valid and corrupt due to the partial > copy. > > Reported-by: Graham Cobb <g.btrfs@xxxxxxxxxxx> > Link: https://lore.kernel.org/linux-btrfs/d0a97688-78be-08de-ca7d-bcb4c7fb397e@xxxxxxxxxxx/ > Fixes: 06fe39ab15a6a4 ("Btrfs: do not overwrite scrub error with fault error in scrub ioctl") > Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx> Added to 5.5-rc queue, thanks.
