--- Revision None
+++ Revision 666466646436
@@ -0,0 +1,131 @@
+commit 362290ea03b52e4ce4edb43453a51a3b1f1cd33f
+Author: Filipe David Borba Manana <fdmanana@gmail.com>
+Date:   Sat Apr 5 22:34:45 2014 +0100
+
+    Btrfs: send, don't issue unnecessary file truncate commands
+    
+    Every time a file is created or updated, send (either incremental or not) always
+    issues a file truncate command. In several commons scenarios this truncate is not
+    needed and yet it was still issued all the time. The unnecessary cases where the
+    truncate command is not needed are:
+    
+    * We have a new file, and its last extent isn't a hole, so that its last write
+      command ends at the file's size;
+    
+    * For an incremental send, we updated in place an existing file, without changing
+      its size;
+    
+    * For an incremental send, we updated the file, increased its size, and the last
+      file extent item doesn't correspond to a hole. In this case the last write
+      command against the file ends at the file's new size;
+    
+    * For an incremental send, we didn't update the file's data at all, we only changed
+      its mode, group or access/update timestamps.
+    
+    Therefore don't send truncate commands for these cases, reducing the stream's size
+    and saving time.
+
+diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
+index fa378c7ebffd..46f52b4bbc21 100644
+--- a/fs/btrfs/send.c
++++ b/fs/btrfs/send.c
+@@ -120,6 +120,7 @@ struct send_ctx {
+ 	u64 cur_inode_mode;
+ 	u64 cur_inode_rdev;
+ 	u64 cur_inode_last_extent;
++	u64 cur_inode_max_write_end;
+ 
+ 	u64 send_progress;
+ 	u64 total_data_size;
+@@ -4494,6 +4495,8 @@ static int send_hole(struct send_ctx *sctx, u64 end)
+ 			break;
+ 		offset += len;
+ 	}
++	sctx->cur_inode_max_write_end = max(offset,
++					    sctx->cur_inode_max_write_end);
+ tlv_put_failure:
+ 	fs_path_free(p);
+ 	return ret;
+@@ -4529,6 +4532,10 @@ static int send_write_or_clone(struct send_ctx *sctx,
+ 		len = btrfs_file_extent_num_bytes(path->nodes[0], ei);
+ 	}
+ 
++	if (offset >= sctx->cur_inode_size) {
++		ret = 0;
++		goto out;
++	}
+ 	if (offset + len > sctx->cur_inode_size)
+ 		len = sctx->cur_inode_size - offset;
+ 	if (len == 0) {
+@@ -4560,6 +4567,8 @@ static int send_write_or_clone(struct send_ctx *sctx,
+ 		}
+ 		ret = 0;
+ 	}
++	sctx->cur_inode_max_write_end = max(offset + len,
++					    sctx->cur_inode_max_write_end);
+ out:
+ 	return ret;
+ }
+@@ -4982,6 +4991,7 @@ static int finish_inode_if_needed(struct send_ctx *sctx, int at_end)
+ 	u64 right_gid;
+ 	int need_chmod = 0;
+ 	int need_chown = 0;
++	int need_truncate = 1;
+ 	int pending_move = 0;
+ 	int refs_processed = 0;
+ 
+@@ -5022,9 +5032,13 @@ static int finish_inode_if_needed(struct send_ctx *sctx, int at_end)
+ 		need_chown = 1;
+ 		if (!S_ISLNK(sctx->cur_inode_mode))
+ 			need_chmod = 1;
++		if (sctx->cur_inode_max_write_end == sctx->cur_inode_size)
++			need_truncate = 0;
+ 	} else {
++		u64 old_size;
++
+ 		ret = get_inode_info(sctx->parent_root, sctx->cur_ino,
+-				NULL, NULL, &right_mode, &right_uid,
++				&old_size, NULL, &right_mode, &right_uid,
+ 				&right_gid, NULL);
+ 		if (ret < 0)
+ 			goto out;
+@@ -5033,6 +5047,13 @@ static int finish_inode_if_needed(struct send_ctx *sctx, int at_end)
+ 			need_chown = 1;
+ 		if (!S_ISLNK(sctx->cur_inode_mode) && left_mode != right_mode)
+ 			need_chmod = 1;
++
++		if (old_size == sctx->cur_inode_size &&
++		    sctx->cur_inode_max_write_end <= sctx->cur_inode_size)
++			need_truncate = 0;
++		else if (sctx->cur_inode_size > old_size &&
++			 sctx->cur_inode_max_write_end == sctx->cur_inode_size)
++			need_truncate = 0;
+ 	}
+ 
+ truncate_inode:
+@@ -5052,10 +5073,13 @@ static int finish_inode_if_needed(struct send_ctx *sctx, int at_end)
+ 					goto out;
+ 			}
+ 		}
+-		ret = send_truncate(sctx, sctx->cur_ino, sctx->cur_inode_gen,
+-				sctx->cur_inode_size);
+-		if (ret < 0)
+-			goto out;
++		if (need_truncate) {
++			ret = send_truncate(sctx, sctx->cur_ino,
++					    sctx->cur_inode_gen,
++					    sctx->cur_inode_size);
++			if (ret < 0)
++				goto out;
++		}
+ 	}
+ 
+ 	if (need_chown) {
+@@ -5110,6 +5134,7 @@ static int changed_inode(struct send_ctx *sctx,
+ 	sctx->cur_ino = key->objectid;
+ 	sctx->cur_inode_new_gen = 0;
+ 	sctx->cur_inode_last_extent = (u64)-1;
++	sctx->cur_inode_max_write_end = 0;
+ 
+ 	/*
+ 	 * Set send_progress to current inode. This will tell all get_cur_xxx