pNFS/flexfiles: Fix list corruption if the mirror count changes

commit 8b04013737341442ed914b336cde866b902664ae upstream.

If the mirror count changes in the new layout we pick up inside
ff_layout_pg_init_write(), then we can end up adding the
request to the wrong mirror and corrupting the mirror->pg_list.

Fixes: d600ad1f2bdb ("NFS41: pop some layoutget errors to application")
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index 4539008502ce65c09cf2a5e0e16d4e29e59827c2..83149cbae093105d7e64d30ff6febc76027e1165 100644 (file)
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -939,9 +939,8 @@ retry:
                goto out_mds;
 
        /* Use a direct mapping of ds_idx to pgio mirror_idx */
-       if (WARN_ON_ONCE(pgio->pg_mirror_count !=
-           FF_LAYOUT_MIRROR_COUNT(pgio->pg_lseg)))
-               goto out_mds;
+       if (pgio->pg_mirror_count != FF_LAYOUT_MIRROR_COUNT(pgio->pg_lseg))
+               goto out_eagain;
 
        for (i = 0; i < pgio->pg_mirror_count; i++) {
                ds = nfs4_ff_layout_prepare_ds(pgio->pg_lseg, i, true);
@@ -960,11 +959,15 @@ retry:
        }
 
        return;
-
+out_eagain:
+       pnfs_generic_pg_cleanup(pgio);
+       pgio->pg_error = -EAGAIN;
+       return;
 out_mds:
        pnfs_put_lseg(pgio->pg_lseg);
        pgio->pg_lseg = NULL;
        nfs_pageio_reset_write_mds(pgio);
+       pgio->pg_error = -EAGAIN;
 }
 
 static unsigned int