Re: sk_lock: inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-W} usage

From: KOSAKI Motohiro
Date: Mon Jun 08 2009 - 02:12:27 EST


> btw, can anyone explain these NFS warnings? It happens in a very
> memory tight and busy nfsroot system.
>
> [ 113.267340] NFS: Server wrote zero bytes, expected 3671.
> [ 423.202607] NFS: Server wrote zero bytes, expected 108.
> [ 723.588411] NFS: Server wrote zero bytes, expected 560.
> [ 1060.246747] NFS: Server wrote zero bytes, expected 54.
> [ 1397.841183] NFS: Server wrote zero bytes, expected 402.
> [ 1779.545035] NFS: Server wrote zero bytes, expected 319.

server side write function is below

-----------------------------------------------------------
static __be32
nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
loff_t offset, struct kvec *vec, int vlen,
unsigned long *cnt, int *stablep)
{
(snip)
host_err = vfs_writev(file, (struct iovec __user *)vec, vlen, &offset); //(1)

(snip)
/*
* Gathered writes: If another process is currently
* writing to the file, there's a high chance
* this is another nfsd (triggered by a bulk write
* from a client's biod). Rather than syncing the
* file with each write request, we sleep for 10 msec.
*
* I don't know if this roughly approximates
* C. Juszak's idea of gathered writes, but it's a
* nice and simple solution (IMHO), and it seems to
* work:-)
*/
if (EX_WGATHER(exp)) {
(snip)
if (inode->i_state & I_DIRTY) {
dprintk("nfsd: write sync %d\n", task_pid_nr(current));
host_err=nfsd_sync(file); // (2)
}
}
(snip)
dprintk("nfsd: write complete host_err=%d\n", host_err);
if (host_err >= 0) {
err = 0;
*cnt = host_err;
} else
err = nfserrno(host_err);
out:
return err;
}
---------------------------------------------------------------------------

if (1) or (2) makes host_err == 0, it makes your warning messages.

Thanks.



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