On 14-04-03 01:16 PM, J. Bruce Fields wrote: > On Thu, Apr 03, 2014 at 12:33:55PM -0400, Mark Lord wrote: >> This commit from linux-3.14 breaks our NFS-root clients here: >> >> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6e14b46b91fee8a049b0940333ce13a820beaaa5 >> >> >> - *p++ = htonl((u32) stat->mode); >> + *p++ = htonl((u32) (stat->mode & S_IALLUGO)); >> >> >> Reverting the one-liner above (on the server) fixes it for us, >> as does reverting back to linux-3.13.8 on the server. >> >> The NFS-root clients are on PowerPC (big-endian) architecture, >> running linux-3.12.16. The NFS server is on an Intel PC running linux-3.14. >> >> ACL is completely disabled on server and client, >> and we're using NFSv2/v3. No support for v4. >> >> I instrumented the function to see what other bits were being cleared >> by the (stat->mode & S_IALLUGO) masking. The results are attached. > > Hm, it sounds like a bug in the client if it's depending on those high > bits. But only for mounting / starting up from the nfsroot, it seems. I wonder if there's an unusual code path for that in there? The regular stuff looks mostly fine: p = xdr_decode_ftype3(p, &fmode); fattr->mode = (be32_to_cpup(p++) & ~S_IFMT) | fmode; Except perhaps that second line ought to use the same mask as the server side is using, just in case there are some other stray high (higher than S_IFMT) bits in there now/someday. > The original behavior was in practice harmless and changing it broke > something, so I think we should definitely just revert this patch. Yup. Who? > But the client may need fixing too. Probably a good thing in the longer term, for better compatibility with non-Linux servers. But we'll still have to keep the revert on the server (nfsd) code for backward compatibility, I think. Cheers -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
