From: Baptiste Lepers <baptiste.lepers@gmail.com>
Date: Mon, 6 Sep 2021 11:59:24 +1000
Subject: [PATCH] pnfs/flexfiles: Fix misplaced barrier in
nfs4_ff_layout_prepare_ds
Git-commit: a2915fa06227b056a8f9b0d79b61dca08ad5cfc6
Patch-mainline: v5.16
References: git-fixes
_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@gmail.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Acked-by: NeilBrown <neilb@suse.com>
---
fs/nfs/flexfilelayout/flexfilelayoutdev.c | 4 ++--
fs/nfs/pnfs_nfs.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)
--- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c
+++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
@@ -408,10 +408,10 @@ nfs4_ff_layout_prepare_ds(struct pnfs_la
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.
--- a/fs/nfs/pnfs_nfs.c
+++ b/fs/nfs/pnfs_nfs.c
@@ -663,7 +663,7 @@ static int _nfs4_pnfs_v3_ds_connect(stru
}
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;
@@ -736,7 +736,7 @@ static int _nfs4_pnfs_v4_ds_connect(stru
}
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;