ceph: use ihold when we already have an inode ref

We should use ihold whenever we already have a stable inode ref, even
when we aren't holding i_lock.  This avoids adding new and unnecessary
locking dependencies.

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 1f72b00..f605753 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2940,14 +2940,12 @@
 	while (!list_empty(&mdsc->cap_dirty)) {
 		ci = list_first_entry(&mdsc->cap_dirty, struct ceph_inode_info,
 				      i_dirty_item);
-		inode = igrab(&ci->vfs_inode);
+		inode = &ci->vfs_inode;
+		ihold(inode);
 		dout("flush_dirty_caps %p\n", inode);
 		spin_unlock(&mdsc->cap_dirty_lock);
-		if (inode) {
-			ceph_check_caps(ci, CHECK_CAPS_NODELAY|CHECK_CAPS_FLUSH,
-					NULL);
-			iput(inode);
-		}
+		ceph_check_caps(ci, CHECK_CAPS_NODELAY|CHECK_CAPS_FLUSH, NULL);
+		iput(inode);
 		spin_lock(&mdsc->cap_dirty_lock);
 	}
 	spin_unlock(&mdsc->cap_dirty_lock);