Re: [RFC v4 linux-next 19/19] fs & block: remove bdev->bd_inode

[Yu Kuai <yukuai1@huaweicloud.com>]

Hi,

在 2024/03/18 5:38, Christoph Hellwig 写道:
> On Thu, Feb 22, 2024 at 08:45:55PM +0800, Yu Kuai wrote:
>> The only user that doesn't rely on files is the block layer itself in
>> block/fops.c where we only have access to the block device. As the bdev
>> filesystem doesn't open block devices as files obviously.
> 
> Why is that obvious?  Maybe I'm just thick but this seems odd to me.

Because there is a real filesystem(devtmpfs) used for raw block devcie
file operations, open syscall to devtmpfs:

blkdev_open
  bdev = blkdev_get_no_open
  bdev_open -> pass in file is from devtmpfs
  -> in this case, file inode is from devtmpfs,

Then later, in blkdev_iomap_begin(), bd_inode is passed in and there is
no access to the devtmpfs file, we can't use s_bdev_file() as other
filesystems here.

Thanks,
Kuai

> 
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