On 04/03/2014 06:57 PM, Dave Reisner wrote: > Hi, > > [This is a repost of a G+ post at Tejun's request] > > With Linux 3.14, you might notice in /proc/self/mountinfo that your > root's parent FSID is now 0, instead of the 1 that it's been for the > last N years. Tejun wrote the change (9e30cc9595303b27b48) that caused > this, but the change comes in a rather innocuous way. Instead of an > internal kernel mount of sysfs being assigned 0, it's now the initramfs. > > So far, this has already caused switch_root and findmnt (from > util-linux) to break, cp (from coreutils) to break when using the -x > flag in early userspace, and it's also been pointed out that systemd's > readahead code makes assumptions about a device number of 0.
For reference we've changed coreutils not to assume 0 is an invalid device ID: http://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commit;h=d0294ff3 > Are we now supposed to go and change all the assumptions in userspace > about 0 being special? I'm conflicted. The kernel isn't supposed to > break userspace, but it seems to me that FSIDs were never something to > rely on -- similar to the block device numbering scheme. I would say the kernel doesn't care what the value is, so to ease compat worries just use >= 1. cheers, Pádraig -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/