Re: [f2fs-dev] f2fs do DIO write make file corruption

From: Chao Yu
Date: Thu Aug 12 2021 - 08:17:59 EST


On 2021/8/12 10:55, Wu Bo wrote:

在 2021/8/11 20:57, Chao Yu 写道:
On 2021/8/11 11:28, Wu Bo wrote:

在 2021/8/11 11:03, Chao Yu 写道:
On 2021/8/11 10:48, Wu Bo wrote:
I use the following command to create a file, the file may got
corruption:
     f2fs_io write 2 0 512 inc_num dio $path

And when I use bio or to set the chunk size to 1 block, the file is
normal. The commands as following:
     f2fs_io write 2 0 512 inc_num buffered $path
     f2fs_io write 1 0 512 inc_num dio $path

I find this bug on old kernel version 4.14.117, and not find on version
4.19.152. So this bug is fixed. Can anyone can tell me which patch
fixed
this bug?

Not sure,

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.19.y&id=7bae8b6b73e46c307fa355ce086800b7ad6610f8


I didn't see this patch in 4.14 stable kernel of mailine, so do you mean
4.14 kernel
maintained by Android?

If so, f2fs codes in between 4.14 and 4.19 Android kernel are almost the
same,
see below link:

https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs-stable.git/


Sorry, it's our old Android project code.So the kernel version may have
no reference value.
This project code last sync to Android common kernel is:
9f892496fc0b:f2fs: readahead encrypted block during GC[2018-09-05]
The code link is:
https://android.googlesource.com/kernel/common/+/9f892496fc0b
And after that, we applied some fixup patches.

I think you can pick up patches from your 4.19 f2fs codes which are not in
your 4.14 f2fs codes, and check each patch you picked to see whether there
is a patch can fix that problem.

Thanks,


Thanks,



This patch is applied. The issue occurs when f2fs dio try to preallocate
multiple blocks and got scattered disk blocks. The log as following:
        my_f2fs_io-13425 [002] ....   395.583637: el0_irq_naked:
1:type:1,ino:40132,off:768,old_blk:0,new_blk:185764
        my_f2fs_io-13425 [002] ....   395.583710: el0_irq_naked:
1:type:1,ino:40132,off:769,old_blk:0,new_blk:205824
        my_f2fs_io-13425 [002] ....   395.583721: f2fs_map_blocks: dev =
(259,23), ino = 40132, file offset = 768, start blkaddr = 0x2d5a4, len =
0x2, err = 0
        my_f2fs_io-13425 [002] ....   395.583735: f2fs_map_blocks: dev =
(259,23), ino = 40132, file offset = 768, start blkaddr = 0x2d5a4, len =
0x1, err = 0
        my_f2fs_io-13425 [002] ....   395.583741: f2fs_map_blocks: dev =
(259,23), ino = 40132, file offset = 769, start blkaddr = 0x32400, len =
0x1, err = 0

And if the blocks are continuously, the file data is normal:
      my_f2fs_io-13425 [002] ....   395.584037: el0_irq_naked:
1:type:1,ino:40132,off:770,old_blk:0,new_blk:205825
        my_f2fs_io-13425 [002] ....   395.584066: el0_irq_naked:
1:type:1,ino:40132,off:771,old_blk:0,new_blk:205826
        my_f2fs_io-13425 [002] ....   395.584077: f2fs_map_blocks: dev =
(259,23), ino = 40132, file offset = 770, start blkaddr = 0x32401, len =
0x2, err = 0
        my_f2fs_io-13425 [002] ....   395.584091: f2fs_map_blocks: dev =
(259,23), ino = 40132, file offset = 770, start blkaddr = 0x32401, len =
0x2, err = 0


Thanks,



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