+ /* blocks to modify */
+ blocks = ((pos + size + bs - 1) >> bits) - (pos >> bits);
+ LASSERT(blocks > 0);
+
+ if (inode != NULL && _pos != -1) {
+ /* object size in blocks */
+ est = (i_size_read(inode) + bs - 1) >> bits;
+ allocated = inode->i_blocks >> (bits - 9);
+ if (pos + size <= i_size_read(inode) && est <= allocated) {
+ /* looks like an overwrite, no need to modify tree */
+ credits = blocks;
+ /* no need to modify i_size */
+ goto out;
+ }
+ }
+
+ if (osd_extents_enabled(sb, inode)) {
+ /*
+ * many concurrent threads may grow tree by the time
+ * our transaction starts. so, consider 2 is a min depth
+ * for every level we may need to allocate a new block
+ * and take some entries from the old one. so, 3 blocks
+ * to allocate (bitmap, gd, itself) + old block - 4 per
+ * level.
+ */
+ depth = inode != NULL ? ext_depth(inode) : 0;
+ depth = max(depth, 1) + 1;
+ credits = depth;
+ /* if not append, then split may need to modify
+ * existing blocks moving entries into the new ones */
+ if (_pos == -1)
+ credits += depth;
+ /* blocks to store data: bitmap,gd,itself */
+ credits += blocks * 3;
+ } else {
+ credits = osd_calc_bkmap_credits(sb, inode, size, _pos, blocks);
+ }
+ /* if inode is created as part of the transaction,
+ * then it's counted already by the creation method */
+ if (inode != NULL)
+ credits++;
+
+out: