ceph: fix xattr cap writeback

We should include the xattr metadata blob in the cap update message any
time we are flushing dirty state, NOT just when we are also dropping the
cap.  This fixes async xattr writeback.

Also, clean up the code slightly to avoid duplicating the bit test.

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 7bf182b..0ac2703 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -1082,6 +1082,7 @@
 	gid_t gid;
 	struct ceph_mds_session *session;
 	u64 xattr_version = 0;
+	struct ceph_buffer *xattr_blob = NULL;
 	int delayed = 0;
 	u64 flush_tid = 0;
 	int i;
@@ -1160,9 +1161,10 @@
 	gid = inode->i_gid;
 	mode = inode->i_mode;
 
-	if (dropping & CEPH_CAP_XATTR_EXCL) {
+	if (flushing & CEPH_CAP_XATTR_EXCL) {
 		__ceph_build_xattrs_blob(ci);
-		xattr_version = ci->i_xattrs.version + 1;
+		xattr_blob = ci->i_xattrs.blob;
+		xattr_version = ci->i_xattrs.version;
 	}
 
 	spin_unlock(&inode->i_lock);
@@ -1170,9 +1172,7 @@
 	ret = send_cap_msg(session, ceph_vino(inode).ino, cap_id,
 		op, keep, want, flushing, seq, flush_tid, issue_seq, mseq,
 		size, max_size, &mtime, &atime, time_warp_seq,
-		uid, gid, mode,
-		xattr_version,
-		(flushing & CEPH_CAP_XATTR_EXCL) ? ci->i_xattrs.blob : NULL,
+		uid, gid, mode, xattr_version, xattr_blob,
 		follows);
 	if (ret < 0) {
 		dout("error sending cap msg, must requeue %p\n", inode);