On Thu, Jul 04, 2013 at 01:51:38PM +0400, Andrew Vagin wrote: > We are not first who suffer from this problem: > https://bugzilla.redhat.com/show_bug.cgi?id=711881 > http://marc.info/?l=linux-btrfs&m=130074451403261 > https://bugzilla.openvz.org/show_bug.cgi?id=2653
> And about 2 years ago Mark Fasheh tried to fix this problem: > http://thr3ads.net/btrfs-devel/2011/05/2346176-RFC-PATCH-0-2-btrfs-vfs-Return-same-device-in-stat-2-and-proc-pid-maps > > Eric Biederman sugested to not create a new method and use vfs_getattr, > but here is a few problems: > * fanotify doesn't have dentry, but its fdinfo contains device. > * vfs_getattr can fail and which device should be shown in this case? > * vfs_getattr gets much more parameters, so here is a question about > performance degradation. > > So I have a question: Can two inodes from different subvolumes have > equal inode numbers? Yes, subvolumes are separate inode number spaces. > If someone have any suggestions how to fix this problem or any > explanation why this is not a problem at all, please write here. The xstat syscall instead of the potentially heavyweight vfs_getattr could fix that, but it's not merged. For suse kernels we've taken the hackish approach of patching fs/proc/task_mmu.c:show_map_vma() (and the nommu variant) and use vfs_getattr only for btrfs. http://kernel.opensuse.org/cgit/kernel-source/tree/patches.suse/btrfs-use-correct-device-for-maps.patch?id=2434fa6ee93a83b117461eb13f24272606677fec Only a temporary and not upstreamable solution, but without it the core packaging tool zypper would not work correctly. david -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
