Messages in this thread | | | From | Luke Dashjr <> | Subject | Re: [PATCH] btrfs: bugfix: handle FS_IOC32_{GETFLAGS,SETFLAGS,GETVERSION} in btrfs_ioctl | Date | Fri, 15 May 2015 16:35:45 +0000 |
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On Friday, May 15, 2015 11:19:22 AM David Sterba wrote: > On Thu, May 14, 2015 at 04:27:54PM +0000, Luke Dashjr wrote: > > On Thursday, May 14, 2015 2:06:17 PM David Sterba wrote: > > > On Wed, May 13, 2015 at 05:15:26PM +0000, Luke Dashjr wrote: > > > > 32-bit ioctl uses these rather than the regular FS_IOC_* versions. > > > > They can be handled in btrfs using the same code. Without this, > > > > 32-bit {ch,ls}attr fail. > > > > > > Yes, but this has to be implemented in another way. See eg. > > > https://git.kernel.org/linus/e9750824114ff > > > > I don't see what is different with that implementation. All > > f2fs_compat_ioctl does is change cmd to the plain-IOC equivalent and > > call f2fs_ioctl with the same arg (compat_ptr merely causes a cast to > > void* and back, which AFAIK is a noop on 64-bit?). Am I missing > > something? > > No, that's the idea. Add new calback for compat_ioctl, put it under > #ifdef CONFIG_COMPAT and do the same number switch.
The idea is to wrap it in a way that doesn't actually change any of the logic? I'm not sure I understand still :(
> > I could try to just imitate it, but > > I'd rather know what is significant/going on to ensure I don't waste your > > time with code I don't even properly understand myself. > > > > Perhaps by coincidence, the patch does at least in practice work > > (although at least `btrfs send` appears to be broken still, and I'm at a > > loss for how to approach fixing that). > > The 'receive' 32bit/64bit was broken due to size difference in the ioctl > structure that led to different ioctl. This is transparently fixed, see > BTRFS_IOC_SET_RECEIVED_SUBVOL_32 at the top of ioctl.c. > > In what way is SEND broken? There are only u64/s64 members in > btrfs_ioctl_send_args, I don't see how this could break on 32/64 > userspace/kernel.
# btrfs send -p home/initial/ home/20150514_1431573370/ At subvol home/20150514_1431573370/ ERROR: send ioctl failed with -25: Inappropriate ioctl for device
But I am stuck on 3.14.41 due to Linux being unstable in newer versions[1], so maybe this is unrelated to 32-bit and already fixed in 4.0?
Luke
1. https://bugzilla.kernel.org/show_bug.cgi?id=87891
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