Re: [Bug #14472] EXT4 corruption

Theodore Tso
2009-10-29T22:23:35Z

On Thu, Oct 29, 2009 at 03:57:32PM -0400, Andrew Lutomirski wrote:
>
> This but is *not* fixed. I just triggered it a few minutes ago by
> abusing i915 and drm, which caused a panic. This is slightly newer
> than 2.6.32-rc5, with a couple of i915 bugfixes thrown in.

Andrew, can you test to see if this patch helps?

Thanks,

- Ted

commit a8836b1d6f92273e001012c7705ae8f4c3d5fb65
Author: Aneesh Kumar K.V <aneesh.kumar-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
Date: Tue Oct 27 15:36:38 2009 +0530

ext4: discard preallocation during truncate

We need to make sure when we drop and reacquire the inode's
i_data_sem we discard the inode preallocation. Otherwise we
could have blocks marked as free in bitmap but still belonging
to prealloc space.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 5c5bc5d..a1ef1c3 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -209,6 +209,12 @@ static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
up_write(&EXT4_I(inode)->i_data_sem);
ret = ext4_journal_restart(handle, blocks_for_truncate(inode));
down_write(&EXT4_I(inode)->i_data_sem);
+ /*
+ * We have dropped i_data_sem. So somebody else could have done
+ * block allocation. So discard the prealloc space created as a
+ * part of block allocation
+ */
+ ext4_discard_preallocations(inode);

return ret;
}