On Thu, 9 Jan 2014 16:33:35 -0500
"J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote:
> Eric ran across an excessive stack with this (and a bunch of xfs code)
> to blame. Untested. I don't know whether it's worth the minor extra
> work here to avoid the alloc/free on each entry.
>
> nfsd4_encode_fattr will need the same treatment.
>
> --b.
>
> commit 5b35a1f99f999555e82420e687e9d079ae796547
> Author: J. Bruce Fields <bfields@xxxxxxxxxx>
> Date: Thu Jan 9 16:24:35 2014 -0500
>
> nfsd: fix encode_entryplus_baggage stack usage
>
> We stick an extra svc_fh in nfsd3_readdirres to save the need to
> kmalloc, though maybe it would be fine to kmalloc instead.
>
> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
>
> diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
> index 1ee6bae..de6e39e 100644
> --- a/fs/nfsd/nfs3xdr.c
> +++ b/fs/nfsd/nfs3xdr.c
> @@ -842,21 +842,21 @@ out:
>
> static __be32 *encode_entryplus_baggage(struct nfsd3_readdirres *cd, __be32 *p, const char *name, int namlen)
> {
> - struct svc_fh fh;
> + struct svc_fh *fh = &cd->scratch;
> __be32 err;
>
> - fh_init(&fh, NFS3_FHSIZE);
> - err = compose_entry_fh(cd, &fh, name, namlen);
> + fh_init(fh, NFS3_FHSIZE);
> + err = compose_entry_fh(cd, fh, name, namlen);
> if (err) {
> *p++ = 0;
> *p++ = 0;
> goto out;
> }
> - p = encode_post_op_attr(cd->rqstp, p, &fh);
> + p = encode_post_op_attr(cd->rqstp, p, fh);
> *p++ = xdr_one; /* yes, a file handle follows */
> - p = encode_fh(p, &fh);
> + p = encode_fh(p, fh);
> out:
> - fh_put(&fh);
> + fh_put(fh);
> return p;
> }
>
> diff --git a/fs/nfsd/xdr3.h b/fs/nfsd/xdr3.h
> index b6d5542..335e04a 100644
> --- a/fs/nfsd/xdr3.h
> +++ b/fs/nfsd/xdr3.h
> @@ -174,6 +174,9 @@ struct nfsd3_linkres {
> struct nfsd3_readdirres {
> __be32 status;
> struct svc_fh fh;
> + /* Just to save kmalloc on every readdirplus entry (svc_fh is a
> + * little large for the stack): */
> + struct svc_fh scratch;
> int count;
> __be32 verf[2];
>
I think this is probably the best solution...
Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>
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