On Wed, Jul 02, 2014 at 04:40:15PM +0800, Kinglong Mee wrote: > > On 7/1/2014 19:21, Avi Kivity wrote: > > On 06/26/2014 05:23 PM, Avi Kivity wrote: > >> XDR requires 4-byte alignment; nfs4d READLINK reply writes out the padding, > >> but truncates the packet to the padding-less size. > >> > >> Fix by taking the padding into consideration when truncating the packet. > >> > > > > Ping. I should have mentioned that without this, readlink() returns an I/O error on the client. Thanks, queueing up for 3.16. > Yes, I got > [root@localhost ~]# ll /mnt/ > ls: cannot read symbolic link /mnt/test: Input/output error > total 4 > -rw-r--r--. 1 root root 0 Jun 14 01:21 123456 > lrwxrwxrwx. 1 root root 6 Jul 2 03:33 test > drwxr-xr-x. 1 root root 0 Jul 2 23:50 tmp > drwxr-xr-x. 1 root root 60 Jul 2 23:44 tree > [root@localhost ~]# > > It's introduced by commit 476a7b1f4b2c (nfsd4: don't treat readlink like a zero-copy operation). ... > >> + xdr_truncate_encode(xdr, length_offset + 4 + ALIGN(maxcount, 4)); > > NFSD uses (XDR_QUADLEN(maxcount) << 2)) usually. Eh, I didn't know about ALIGN()--I think I prefer it. > Anyway, it's a nice fix. > > Reviewed-by: Kinglong Mee <kinglongmee@xxxxxxxxx> Thanks! I've also added your symptoms and the problematic commit to the changelog. --b. -- 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
