[ 3.5.y.z extended stable ] Patch "ext4: fix the wrong number of the allocated blocks in" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ext4: fix the wrong number of the allocated blocks in

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 75ca3e8062cd6ee5c0371efeb99a0d743307a700 Mon Sep 17 00:00:00 2001
From: Zheng Liu <wenqing.lz at taobao.com>
Date: Sun, 10 Mar 2013 21:20:23 -0400
Subject: [PATCH] ext4: fix the wrong number of the allocated blocks in
 ext4_split_extent()

commit 3a2256702e47f68f921dfad41b1764d05c572329 upstream.

This commit fixes a wrong return value of the number of the allocated
blocks in ext4_split_extent.  When the length of blocks we want to
allocate is greater than the length of the current extent, we return a
wrong number.  Let's see what happens in the following case when we
call ext4_split_extent().

  map: [48, 72]
  ex:  [32, 64, u]

'ex' will be split into two parts:
  ex1: [32, 47, u]
  ex2: [48, 64, w]

'map->m_len' is returned from this function, and the value is 24.  But
the real length is 16.  So it should be fixed.

Meanwhile in this commit we use right length of the allocated blocks
when get_reserved_cluster_alloc in ext4_ext_handle_uninitialized_extents
is called.

Signed-off-by: Zheng Liu <wenqing.lz at taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso at mit.edu>
Cc: Dmitry Monakhov <dmonakhov at openvz.org>
[ luis: adjust context ]
Luis Henriques <luis.henriques at canonical.com>
---
 fs/ext4/extents.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index d14487e..5101df2 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3029,6 +3029,7 @@ static int ext4_split_extent(handle_t *handle,
 	int err = 0;
 	int uninitialized;
 	int split_flag1, flags1;
+	int allocated = map->m_len;

 	depth = ext_depth(inode);
 	ex = path[depth].p_ext;
@@ -3048,6 +3049,8 @@ static int ext4_split_extent(handle_t *handle,
 				map->m_lblk + map->m_len, split_flag1, flags1);
 		if (err)
 			goto out;
+	} else {
+		allocated = ee_len - (map->m_lblk - ee_block);
 	}

 	ext4_ext_drop_refs(path);
@@ -3070,7 +3073,7 @@ static int ext4_split_extent(handle_t *handle,

 	ext4_ext_show_leaf(inode, path);
 out:
-	return err ? err : map->m_len;
+	return err ? err : allocated;
 }

 #define EXT4_EXT_ZERO_LEN 7
@@ -3738,6 +3741,7 @@ out:
 					allocated - map->m_len);
 		allocated = map->m_len;
 	}
+	map->m_len = allocated;

 	/*
 	 * If we have done fallocate with the offset that is already
--
1.8.1.2