[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH 1/3] ext2fs: remove inappropriate assertion
From: |
Samuel Thibault |
Subject: |
Re: [PATCH 1/3] ext2fs: remove inappropriate assertion |
Date: |
Tue, 25 Mar 2014 02:23:39 +0100 |
User-agent: |
Mutt/1.5.21+34 (58baf7c9f32f) (2010-12-30) |
Justus Winter, le Thu 20 Mar 2014 14:01:18 +0100, a écrit :
> find_block may very well return no error but set block to zero. This
> indicates that the block in question has not been allocated. Skip
> those blocks instead.
Mmm, I don't think we want to skip them. AIUI (but don't take my words
for granted, I'm only speculating without checking the details), what
can roughly happens can be
dd < /dev/zero > blip bs=1M count=1 seek=1000
then mmap it to some process (MAP_SHARED), then write to the mapped
memory, and then sync that. AIUI pager_write_page ends up being called
to write back the values to the file, and even if it's not allocated
yet, we want to write that.
That being said, I don't manage to reproduce the scenario and get a
crash there. Do you have a reproducer?
Samuel