On Thu, Mar 21, 2024 at 08:15:06PM +0800, Yu Kuai wrote:

quoted

blkdev_iomap_begin() etc. may be an arbitrary filesystem block device
inode. But why can't you use I_BDEV(inode->i_mapping->host) to get to the
block device instead of your file_bdev(inode->i_private)? I don't see any
advantage in stashing away that special bdev_file into inode->i_private but
perhaps I'm missing something...

Because we're goning to remove the 'block_device' from iomap and
buffer_head, and replace it with a 'bdev_file'.

What of that?  file_inode(file)->f_mapping->host will give you bdevfs inode
just fine...