From: Baptiste Lepers <baptiste.lepers@xxxxxxxxx>
[ 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: d67ae825a59d6 ("pnfs/flexfiles: Add the FlexFile Layout Driver")
Signed-off-by: Baptiste Lepers <baptiste.lepers@xxxxxxxxx>
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/nfs/flexfilelayout/flexfilelayoutdev.c | 4 ++--
fs/nfs/pnfs_nfs.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/fs/nfs/flexfilelayout/flexfilelayoutdev.c b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
index 2464b9b806988..17dee8fd9834f 100644
--- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c
+++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
@@ -428,10 +428,10 @@ 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.
diff --git a/fs/nfs/pnfs_nfs.c b/fs/nfs/pnfs_nfs.c
index 29bdf1525d82b..5d7a69ffaaa29 100644
--- a/fs/nfs/pnfs_nfs.c
+++ b/fs/nfs/pnfs_nfs.c
@@ -635,7 +635,7 @@ 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;
@@ -708,7 +708,7 @@ 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;
--
2.33.0
