fs: don't use igrab() while holding i_lock

Fix the incorrect use of igrab() inside the i_lock in NFS and Ceph‥

If we are already holding the i_lock, we have a reference to the
inode so we can safely use ihold() to gain an extra reference. This
avoids hangs due to lock recursion on the i_lock now that the
inode_lock is gone and igrab() uses the i_lock itself.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: Ryan Mallon <ryan@bluewatersys.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 561438b6a50c..37368ba2e67c 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -92,7 +92,7 @@ static int ceph_set_page_dirty(struct page *page)
                 ci->i_head_snapc = ceph_get_snap_context(snapc);
         ++ci->i_wrbuffer_ref_head;
         if (ci->i_wrbuffer_ref == 0)
-                igrab(inode);
+                ihold(inode);
         ++ci->i_wrbuffer_ref;
         dout("%p set_page_dirty %p idx %lu head %d/%d -> %d/%d "
              "snapc %p seq %lld (%d snaps)\n",