From 177353670085c14e1d358db8bf812bd72a9268c7 Mon Sep 17 00:00:00 2001 From: Zheng Liu Date: Fri, 28 Oct 2011 20:34:02 +0800 Subject: [PATCH] ext4: fix BUG_ON() in ext4_ext_insert_extent() Does not corrispond with a direct commit in Linus's tree as it was fixed differently in the 3.0 release. We will meet with a BUG_ON() if following script is run. mkfs.ext4 -b 4096 /dev/sdb1 1000000 mount -t ext4 /dev/sdb1 /mnt/sdb1 fallocate -l 100M /mnt/sdb1/test sync for((i=0;i<170;i++)) do dd if=/dev/zero of=/mnt/sdb1/test conv=notrunc bs=256k count=1 seek=`expr $i \* 2` done umount /mnt/sdb1 mount -t ext4 /dev/sdb1 /mnt/sdb1 dd if=/dev/zero of=/mnt/sdb1/test conv=notrunc bs=256k count=1 seek=341 umount /mnt/sdb1 mount /dev/sdb1 /mnt/sdb1 dd if=/dev/zero of=/mnt/sdb1/test conv=notrunc bs=256k count=1 seek=340 sync The reason is that it forgot to mark dirty when splitting two extents in ext4_ext_convert_to_initialized(). Althrough ex has been updated in memory, it is not dirtied both in ext4_ext_convert_to_initialized() and ext4_ext_insert_extent(). The disk layout is corrupted. Then it will meet with a BUG_ON() when writting at the start of that extent again. Cc: "Theodore Ts'o" Cc: Xiaoyun Mao Cc: Yingbin Wang Cc: Jia Wan Signed-off-by: Zheng Liu Signed-off-by: Greg Kroah-Hartman --- fs/ext4/extents.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index f3755590987..93f7999a092 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -2592,6 +2592,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle, ex1 = ex; ex1->ee_len = cpu_to_le16(iblock - ee_block); ext4_ext_mark_uninitialized(ex1); + ext4_ext_dirty(handle, inode, path + depth); ex2 = &newex; } /* -- 2.11.4.GIT