releases/4.4.44/pnfs-fix-race-in-pnfs_wait_on_layoutreturn.patch

   1 From ee284e35d8c71bf5d4d807eaff6f67a17134b359 Mon Sep 17 00:00:00 2001
   2 From: Trond Myklebust <trond.myklebust@primarydata.com>
   3 Date: Fri, 18 Nov 2016 15:21:30 -0500
   4 Subject: pNFS: Fix race in pnfs_wait_on_layoutreturn
   5
   6 From: Trond Myklebust <trond.myklebust@primarydata.com>
   7
   8 commit ee284e35d8c71bf5d4d807eaff6f67a17134b359 upstream.
   9
  10 We must put the task to sleep while holding the inode->i_lock in order
  11 to ensure atomicity with the test for NFS_LAYOUT_RETURN.
  12
  13 Fixes: 500d701f336b ("NFS41: make close wait for layoutreturn")
  14 Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
  15 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  16
  17 ---
  18  fs/nfs/pnfs.c |    8 +++-----
  19  1 file changed, 3 insertions(+), 5 deletions(-)
  20
  21 --- a/fs/nfs/pnfs.c
  22 +++ b/fs/nfs/pnfs.c
  23 @@ -1185,13 +1185,11 @@ bool pnfs_wait_on_layoutreturn(struct in
  24          * i_lock */
  25          spin_lock(&ino->i_lock);
  26          lo = nfsi->layout;
  27 -        if (lo && test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))
  28 +        if (lo && test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags)) {
  29 +                rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
  30                  sleep = true;
  31 +       }
  32          spin_unlock(&ino->i_lock);
  33 -
  34 -        if (sleep)
  35 -                rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
  36 -
  37          return sleep;
  38  }
  39