On Tue, Feb 25, 2014 at 11:21:26AM +0100, Jan Kara wrote: > On Mon 24-02-14 10:45:32, J. Bruce Fields wrote: > > On Mon, Feb 24, 2014 at 10:55:25AM +0100, Jan Kara wrote: > > > On Sat 22-02-14 09:50:06, Matthew Rahtz wrote: > > > > Thanks for your help Jan, > > > > > > > > A few months later, we've noticed the issue is actually still there. > > > > Using 3.11.0-17-generic on Ubuntu 12.04, we’re seeing this in the kernel > > > > logs: > > > > > > > > [29243.606215] WARNING: CPU: 0 PID: 1785 at > > > > /build/buildd/linux-lts-saucy-3.11.0/fs/ext4/ext4_jbd2.c:48 > > > > ext4_journal_check_start+0x83/0x90() > > > > > > > > Having a look at the Ubuntu source package for that version, it > > > > definitely does include commit 03d95eb2f2578083a3f6286262e1cb5d88a00c02, > > > > and the line generating the warning is still: > > > > > > > > WARN_ON(sb->s_writers.frozen == SB_FREEZE_COMPLETE); > > > > > > > > Are there any other obvious possibilities for what may be causing this? > > > > There seem to be some users of Oracle Linux experiencing similar problems > > > > at https://community.oracle.com/thread/2617418, which was apparently > > > > fixed in Oracle's kernel version '3.8.13-26.el6uek'. Any word on when > > > > this might be integrated into the official kernel? > > > > > > > > Full call trace included below. > > > Looking at the trace below, now the problem seems to be in the NFS server > > > code. NFS should get protection against the filesystem being frozen (or > > > remounted read-only for that matter) via mnt_want_write() before calling > > > into notify_change() (actually before calling fh_lock() because of lock > > > ordering). Similarly to what we do e.g. in fchownat(). Bruce? > > > > Like this? > Yup, that looks right. Ugh, actually, I didn't realize we can't do mnt_want_write recursively, and there's a confusing mixture of callers that do and don't already take it, so I'll have to do something a little more complicated. Oh well.--b. > > > But I wonder why this is just popping up now--as far as I can tell we've > > had the bug since those write counts were introduced. > Yeah, I'm wondering as well. NFS server on ext4 should have been > complaining for a long time. > > Honza > > > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c > > index 6d7be3f..d573b61 100644 > > --- a/fs/nfsd/vfs.c > > +++ b/fs/nfsd/vfs.c > > @@ -445,12 +445,16 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap, > > err = nfserr_notsync; > > goto out_put_write_access; > > } > > + host_err = fh_want_write(fhp); > > + if (host_err) > > + goto out_nfserr; > > > > fh_lock(fhp); > > host_err = notify_change(dentry, iap, NULL); > > fh_unlock(fhp); > > + fh_drop_write(fhp); > > +out_nfserr: > > err = nfserrno(host_err); > > - > > out_put_write_access: > > if (size_change) > > put_write_access(inode); > -- > Jan Kara <jack@xxxxxxx> > SUSE Labs, CR -- 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
