xfs: simplify xfs_idata_realloc

Streamline the code and take advantage of the fact that kmem_realloc
through krealloc will be have like a normal allocation if passing in a
NULL old pointer.

Signed-off-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Darrick J. Wong <[e-mail]>
Signed-off-by: Darrick J. Wong <[e-mail]>

fs/xfs/libxfs/xfs_inode_fork.c

···
  */
 void
 xfs_idata_realloc(
-	xfs_inode_t	*ip,
-	int		byte_diff,
-	int		whichfork)
+	struct xfs_inode	*ip,
+	int			byte_diff,
+	int			whichfork)
 {
-	xfs_ifork_t	*ifp;
-	int		new_size;
-	int		real_size;
+	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	int			new_size = (int)ifp->if_bytes + byte_diff;
 
-	if (byte_diff == 0) {
-		return;
-	}
-
-	ifp = XFS_IFORK_PTR(ip, whichfork);
-	new_size = (int)ifp->if_bytes + byte_diff;
 	ASSERT(new_size >= 0);
+	ASSERT(new_size <= XFS_IFORK_SIZE(ip, whichfork));
+
+	if (byte_diff == 0)
+		return;
 
 	if (new_size == 0) {
 		kmem_free(ifp->if_u1.if_data);
 		ifp->if_u1.if_data = NULL;
-		real_size = 0;
-	} else {
-		/*
-		 * Stuck with malloc/realloc.
-		 * For inline data, the underlying buffer must be
-		 * a multiple of 4 bytes in size so that it can be
-		 * logged and stay on word boundaries.  We enforce
-		 * that here.
-		 */
-		real_size = roundup(new_size, 4);
-		if (ifp->if_u1.if_data == NULL) {
-			ifp->if_u1.if_data = kmem_alloc(real_size,
-							KM_SLEEP | KM_NOFS);
-		} else {
-			/*
-			 * Only do the realloc if the underlying size
-			 * is really changing.
-			 */
-			ifp->if_u1.if_data =
-				kmem_realloc(ifp->if_u1.if_data,
-						real_size,
-						KM_SLEEP | KM_NOFS);
-		}
+		ifp->if_bytes = 0;
+		return;
 	}
+
+	/*
+	 * For inline data, the underlying buffer must be a multiple of 4 bytes
+	 * in size so that it can be logged and stay on word boundaries.
+	 * We enforce that here.
+	 */
+	ifp->if_u1.if_data = kmem_realloc(ifp->if_u1.if_data,
+			roundup(new_size, 4), KM_SLEEP | KM_NOFS);
 	ifp->if_bytes = new_size;
-	ASSERT(ifp->if_bytes <= XFS_IFORK_SIZE(ip, whichfork));
 }
 
 void