Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx1.redhat.com ([209.132.183.28]:39407 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751616AbaAWXH0 (ORCPT ); Thu, 23 Jan 2014 18:07:26 -0500 Date: Thu, 23 Jan 2014 18:07:21 -0500 From: Jeff Layton To: "J. Bruce Fields" Cc: linux-nfs@vger.kernel.org, sandeen@redhat.com Subject: Re: [PATCH] nfsd4: decrease nfsd4_encode_fattr stack usage Message-ID: <20140123180721.402c4ea7@tlielax.poochiereds.net> In-Reply-To: <20140123185304.GA28223@fieldses.org> References: <20140109213335.GA21559@fieldses.org> <20140109191934.5a66c3d8@tlielax.poochiereds.net> <20140123185304.GA28223@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu, 23 Jan 2014 13:53:05 -0500 "J. Bruce Fields" wrote: > From: "J. Bruce Fields" > > A struct svc_fh is 320 bytes on x86_64, it'd be better not to have these > on the stack. > > kmalloc'ing them probably isn't ideal either, but this is the simplest > thing to do. If it turns out to be a problem in the readdir case then > we could add a svc_fh to nfsd4_readdir and pass that in. > > Signed-off-by: J. Bruce Fields > --- > fs/nfsd/nfs4xdr.c | 16 ++++++++++------ > 1 file changed, 10 insertions(+), 6 deletions(-) > > On Thu, Jan 09, 2014 at 07:19:34PM -0500, Jeff Layton wrote: > > On Thu, 9 Jan 2014 16:33:35 -0500 > > > nfsd: fix encode_entryplus_baggage stack usage > ... > > I think this is probably the best solution... > > > > Acked-by: Jeff Layton > > Thanks. While we're at it, here's the v4 case. > > --b. > > diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c > index 8198ecf..63f2395 100644 > --- a/fs/nfsd/nfs4xdr.c > +++ b/fs/nfsd/nfs4xdr.c > @@ -2058,7 +2058,7 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp, > u32 bmval1 = bmval[1]; > u32 bmval2 = bmval[2]; > struct kstat stat; > - struct svc_fh tempfh; > + struct svc_fh *tempfh = NULL; > struct kstatfs statfs; > int buflen = count << 2; > __be32 *attrlenp; > @@ -2105,11 +2105,15 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp, > goto out_nfserr; > } > if ((bmval0 & (FATTR4_WORD0_FILEHANDLE | FATTR4_WORD0_FSID)) && !fhp) { > - fh_init(&tempfh, NFS4_FHSIZE); > - status = fh_compose(&tempfh, exp, dentry, NULL); > + tempfh = kmalloc(sizeof(struct svc_fh), GFP_KERNEL); > + status = nfserr_jukebox; > + if (!tempfh) > + goto out; > + fh_init(tempfh, NFS4_FHSIZE); > + status = fh_compose(tempfh, exp, dentry, NULL); > if (status) > goto out; > - fhp = &tempfh; > + fhp = tempfh; > } > if (bmval0 & (FATTR4_WORD0_ACL | FATTR4_WORD0_ACLSUPPORT > | FATTR4_WORD0_SUPPORTED_ATTRS)) { > @@ -2495,8 +2499,8 @@ out: > security_release_secctx(context, contextlen); > #endif /* CONFIG_NFSD_V4_SECURITY_LABEL */ > kfree(acl); > - if (fhp == &tempfh) > - fh_put(&tempfh); > + if (tempfh) > + fh_put(tempfh); > return status; > out_nfserr: > status = nfserrno(err); Ok, different approach here. You're kmalloc'ing it separately instead of making it part of the nfsd4_readdir struct. Should be fine though... Acked-by: Jeff Layton