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pnfs/flexfiles: Fix misplaced barrier in nfs4_ff_layout_prepare_ds

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_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: d67ae825a5 ("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>
This commit is contained in:
Baptiste Lepers 2021-09-06 11:59:24 +10:00 committed by Trond Myklebust
parent 36a10a3c4c
commit a2915fa062
2 changed files with 4 additions and 4 deletions
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4
fs/nfs/flexfilelayout/flexfilelayoutdev.c
View File

@ -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.

4
fs/nfs/pnfs_nfs.c
View File

@ -895,7 +895,7 @@ 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;
@ -973,7 +973,7 @@ 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;