From: Greg KH <[email protected]>

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Trond Myklebust <[email protected]>

commit 47fbf7976e0b7d9dcdd799e2a1baba19064d9631 upstream.

Ever since commit 0a57cdac3f (NFSv4.1 send layoutreturn to fence
disconnected data server) we've been sending layoutreturn calls
while there is potentially still outstanding I/O to the data
servers. The reason we do this is to avoid races between replayed
writes to the MDS and the original writes to the DS.

When this happens, the BUG_ON() in nfs4_layoutreturn_done can
be triggered because it assumes that we would never call
layoutreturn without knowing that all I/O to the DS is
finished. The fix is to remove the BUG_ON() now that the
assumptions behind the test are obsolete.

Reported-by: Boaz Harrosh <[email protected]>
Reported-by: Tigran Mkrtchyan <[email protected]>
Signed-off-by: Trond Myklebust <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 fs/nfs/nfs4proc.c |    8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -5766,12 +5766,8 @@ static void nfs4_layoutreturn_done(struc
                return;
        }
        spin_lock(&lo->plh_inode->i_lock);
-       if (task->tk_status == 0) {
-               if (lrp->res.lrs_present) {
-                       pnfs_set_layout_stateid(lo, &lrp->res.stateid, true);
-               } else
-                       BUG_ON(!list_empty(&lo->plh_segs));
-       }
+       if (task->tk_status == 0 && lrp->res.lrs_present)
+               pnfs_set_layout_stateid(lo, &lrp->res.stateid, true);
        lo->plh_block_lgets--;
        spin_unlock(&lo->plh_inode->i_lock);
        dprintk("<-- %s\n", __func__);


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