| From 36e75b80398a655deeb9b726a3d6a5e081c4b8a1 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 6 Sep 2021 11:59:24 +1000 |
| Subject: pnfs/flexfiles: Fix misplaced barrier in nfs4_ff_layout_prepare_ds |
| |
| From: Baptiste Lepers <baptiste.lepers@gmail.com> |
| |
| [ 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@gmail.com> |
| Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| 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 3eda40a320a53..1f12297109b41 100644 |
| --- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c |
| +++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c |
| @@ -378,10 +378,10 @@ nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, |
| goto noconnect; |
| |
| 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 249cf9037dbd7..aff44a7b98f86 100644 |
| --- a/fs/nfs/pnfs_nfs.c |
| +++ b/fs/nfs/pnfs_nfs.c |
| @@ -641,7 +641,7 @@ 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; |
| @@ -714,7 +714,7 @@ 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 |
| |