From b5384d48f4e74edec3ca1887cb65e378a72af9a1 Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@newdream.net>
Date: Sat, 12 Jun 2010 22:31:14 +0000
Subject: [PATCH] Btrfs: fix CLONE ioctl destination file size expansion to
 block boundary

The CLONE and CLONE_RANGE ioctls round up the range of extents being
cloned to the block size when the range to clone extends to the end of file
(this is always the case with CLONE).  It was then using that offset when
extending the destination file's i_size.  Fix this by not setting i_size
beyond the originally requested ending offset.

This bug was introduced by a22285a6 (2.6.35-rc1).

Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
---
 fs/btrfs/ioctl.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 4dbaf89b1337..2a8b3a7568ad 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1578,6 +1578,7 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
 			u64 disko = 0, diskl = 0;
 			u64 datao = 0, datal = 0;
 			u8 comp;
+			u64 endoff;
 
 			size = btrfs_item_size_nr(leaf, slot);
 			read_extent_buffer(leaf, buf,
@@ -1712,9 +1713,18 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
 			btrfs_release_path(root, path);
 
 			inode->i_mtime = inode->i_ctime = CURRENT_TIME;
-			if (new_key.offset + datal > inode->i_size)
-				btrfs_i_size_write(inode,
-						   new_key.offset + datal);
+
+			/*
+			 * we round up to the block size at eof when
+			 * determining which extents to clone above,
+			 * but shouldn't round up the file size
+			 */
+			endoff = new_key.offset + datal;
+			if (endoff > off+olen)
+				endoff = off+olen;
+			if (endoff > inode->i_size)
+				btrfs_i_size_write(inode, endoff);
+
 			BTRFS_I(inode)->flags = BTRFS_I(src)->flags;
 			ret = btrfs_update_inode(trans, root, inode);
 			BUG_ON(ret);