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Commit 16645db2 authored by Baptiste Lepers's avatar Baptiste Lepers Committed by Greg Kroah-Hartman
Browse files

pnfs/flexfiles: Fix misplaced barrier in nfs4_ff_layout_prepare_ds 



[ Upstream commit a2915fa06227b056a8f9b0d79b61dca08ad5cfc6 ]

_nfs4_pnfs_v3/v4_ds_connect do
   some work
   smp_wmb
   ds->ds_clp = clp;

And nfs4_ff_layout_prepare_ds currently does
   smp_rmb
   if(ds->ds_clp)
      ...

This patch places the smp_rmb after the if. This ensures that following
reads only happen once nfs4_ff_layout_prepare_ds has checked that data
has been properly initialized.

Fixes: d67ae825 ("pnfs/flexfiles: Add the FlexFile Layout Driver")
Signed-off-by: default avatarBaptiste Lepers <baptiste.lepers@gmail.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 52355fd4

fs/nfs/flexfilelayout/flexfilelayoutdev.c

+2 −2
Original line number Diff line number Diff line
@@ -383,10 +383,10 @@ nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx, 
		goto out_fail;



	ds = mirror->mirror_ds->ds;

	if (READ_ONCE(ds->ds_clp))

		goto out;

	/* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */

	smp_rmb();

	if (ds->ds_clp)

		goto out;



	/* FIXME: For now we assume the server sent only one version of NFS

	 * to use for the DS.

fs/nfs/pnfs_nfs.c

+2 −2
Original line number Diff line number Diff line
@@ -666,7 +666,7 @@ static int _nfs4_pnfs_v3_ds_connect(struct nfs_server *mds_srv, 
	}



	smp_wmb();

	ds->ds_clp = clp;

	WRITE_ONCE(ds->ds_clp, clp);

	dprintk("%s [new] addr: %s\n", __func__, ds->ds_remotestr);

out:

	return status;
@@ -742,7 +742,7 @@ static int _nfs4_pnfs_v4_ds_connect(struct nfs_server *mds_srv, 
	}



	smp_wmb();

	ds->ds_clp = clp;

	WRITE_ONCE(ds->ds_clp, clp);

	dprintk("%s [new] addr: %s\n", __func__, ds->ds_remotestr);

out:

	return status;