Fix kernel BUG at fs/ext4/mballoc.c:910!

From: Valerie Clement <[EMAIL PROTECTED]>

With the flex_bg feature enabled, a large file creation oopses the
The BUG_ON is:
        BUG_ON(len >= EXT4_BLOCKS_PER_GROUP(sb));

As the allocation of the bitmaps and the inode table can be done
outside the block group with flex_bg, this allows to allocate up to
EXT4_BLOCKS_PER_GROUP blocks in a group.
Depending on the group size and the block size, extents might be 
larger than BLOCKS_PER_GROUP(); use EXT_INIT_MAX_LEN instead of 

This patch fixes the oops.

Signed-off-by: Valerie Clement <[EMAIL PROTECTED]>

 fs/ext4/mballoc.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index b0f84b4..ccc33e9 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -34,6 +34,7 @@
 #include <linux/pagemap.h>
 #include <linux/seq_file.h>
 #include <linux/version.h>
+#include <linux/ext4_fs_extents.h>
 #include "group.h"
@@ -907,7 +908,9 @@ static void ext4_mb_mark_free_simple(struct super_block *sb,
        unsigned short chunk;
        unsigned short border;
-       BUG_ON(len >= EXT4_BLOCKS_PER_GROUP(sb));
+                       EXT4_FEATURE_INCOMPAT_FLEX_BG) ? EXT_INIT_MAX_LEN :
+                       EXT4_BLOCKS_PER_GROUP(sb));
        border = 2 << sb->s_blocksize_bits;

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