All of lore.kernel.org
 help / color / mirror / Atom feed
From: Baptiste Lepers <baptiste.lepers@gmail.com>
To: unlisted-recipients:; (no To-header on input)
Cc: Baptiste Lepers <baptiste.lepers@gmail.com>,
	Trond Myklebust <trond.myklebust@hammerspace.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	Chuck Lever <chuck.lever@oracle.com>,
	Tao Peng <bergwolf@primarydata.com>,
	Tom Haynes <loghyr@primarydata.com>,
	Weston Andros Adamson <dros@primarydata.com>,
	linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] pnfs/flexfiles: Fix misplaced barrier in nfs4_ff_layout_prepare_ds
Date: Mon,  6 Sep 2021 11:59:24 +1000	[thread overview]
Message-ID: <20210906015925.13705-1-baptiste.lepers@gmail.com> (raw)

_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>
---
 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 c9b61b818ec1..bfa7202ca7be 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 cf19914fec81..02bd6e83961d 100644
--- a/fs/nfs/pnfs_nfs.c
+++ b/fs/nfs/pnfs_nfs.c
@@ -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;
-- 
2.17.1


                 reply	other threads:[~2021-09-06  1:59 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210906015925.13705-1-baptiste.lepers@gmail.com \
    --to=baptiste.lepers@gmail.com \
    --cc=anna.schumaker@netapp.com \
    --cc=bergwolf@primarydata.com \
    --cc=chuck.lever@oracle.com \
    --cc=dros@primarydata.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-nfs@vger.kernel.org \
    --cc=loghyr@primarydata.com \
    --cc=trond.myklebust@hammerspace.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.