Re: [PATCH] btrfs: use simple_dir_inode_operations for placeholder subvolume directory

[Josef Bacik <josef@toxicpanda.com>]

On Thu, Dec 05, 2019 at 10:36:04AM -0800, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> When you snapshot a subvolume containing a subvolume, you get a
> placeholder directory where the subvolume would be. These directories
> have their own btrfs_dir_ro_inode_operations.
> 
> Al pointed out [1] that these directories can use simple_lookup()
> instead of btrfs_lookup(), as they are always empty. Furthermore, they
> can use the default generic_permission() instead of btrfs_permission();
> the additional checks in the latter don't matter because we can't write
> to the directory anyways. Finally, they can use the default
> generic_update_time() instead of btrfs_update_time(), as the inode
> doesn't exist on disk and doesn't need any special handling.
> 
> All together, this means that we can get rid of
> btrfs_dir_ro_inode_operations and use simple_dir_inode_operations
> instead.
> 
> 1: https://lore.kernel.org/linux-btrfs/20190929052934.GY26530@ZenIV.linux.org.uk/
> 
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Signed-off-by: Omar Sandoval <osandov@fb.com>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef