It looks like I overthink and the best and simple solution is just to use
for all block devices the block_operation function of inode to get geometry:
inode->u.i_bops->geometry
I miss that bchlib is already use this function to fill bchlib_s structure.
Will try this approach now.
пн, 25 мая 2020 г. в 15:03, Oleg Evseev <ev.m...@gmail.com>:
> Hi,
>
> I wonder how to get size of character device that referenced mtd partition
> block device? As I see bchlib_setup in drivers/bch/bchlib_setup.c fills
> block geometry info to bchlib_s structure (number of sectors and sector
> size) that then stored as i_private to inode.
>
> This inode is part of the root pseudo file system and when user call
> stat() code leads to inode_stat function in fs/vfs/fs_stat.c that fills
> only file attributes info (st_mode).
>
> I suppose here inode_stat also could fill size of file in bytes (st_size)
> based on geometry from i_private bchlib_s structure.
>
> But how to correctly determine that device is BCH here, to be sure that
> casting to bchlib_s will be correct? INODE_IS_BLOCK(inode) is obviously not
> enough criteria.
>
> I'm not good in inode stuff, so maybe this is stupid idea, but could I
> check file_operations functions pointers to be equal to certain functions
> of BCH? Something like:
> if (inode->u.i_ops->read == bch_read) {}
>
> Anyway it would be done, fs_stat will be depended on BCH driver. But I
> suppose it is not right, is it?
>
> p.s. also I suppose same thing is related to block devices themselves,
> they could provide geometry info to determine file size for stat().
>
> Thanks for any thoughts!
>
> --
> With regards, Oleg.
>
