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

From: Chao Yu
Date: Wed Aug 11 2021 - 08:57:15 EST


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/

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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