1 files changed, 31 insertions, 1 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 7844bbb2bac0..dabc3b68d249 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -248,6 +248,36 @@ static int ext4_ext_space_root_idx(struct inode *inode)
         return size;
 }
 
+/*
+ * Calculate the number of metadata blocks needed
+ * to allocate @blocks
+ * Worse case is one block per extent
+ */
+int ext4_ext_calc_metadata_amount(struct inode *inode, int blocks)
+{
+        int lcap, icap, rcap, leafs, idxs, num;
+        int newextents = blocks;
+
+        rcap = ext4_ext_space_root_idx(inode);
+        lcap = ext4_ext_space_block(inode);
+        icap = ext4_ext_space_block_idx(inode);
+
+        /* number of new leaf blocks needed */
+        num = leafs = (newextents + lcap - 1) / lcap;
+
+        /*
+         * Worse case, we need separate index block(s)
+         * to link all new leaf blocks
+         */
+        idxs = (leafs + icap - 1) / icap;
+        do {
+                num += idxs;
+                idxs = (idxs + icap - 1) / icap;
+        } while (idxs > rcap);
+
+        return num;
+}
+
 static int
 ext4_ext_max_entries(struct inode *inode, int depth)
 {
@@ -2910,7 +2940,7 @@ retry:
                 }
                 ret = ext4_get_blocks_wrap(handle, inode, block,
                                           max_blocks, &map_bh,
-                                          EXT4_CREATE_UNINITIALIZED_EXT, 0);
+                                          EXT4_CREATE_UNINITIALIZED_EXT, 0, 0);
                 if (ret <= 0) {
 #ifdef EXT4FS_DEBUG
                         WARN_ON(ret <= 0);