Re: [PATCH 28/28] quota: add extra inode count to dquot transfer functions

[Tahsin Erdogan]

On Thu, Jun 15, 2017 at 12:57 AM, Jan Kara <jack@xxxxxxx> wrote:
> Hum, rather handle this similarly to how we handle delalloc reserved space.
> Add a callback to dq_ops to get "inode usage" of an inode and then use it
> in dquot_transfer(), dquot_free_inode(), dquot_alloc_inode().

I tried that approach by adding a "int get_inode_usage(struct inode
*inode, qsize_t *usage)" callback to dquot_operations. Unfortunately,
ext4 code that calculates the number of internal inodes
(ext4_xattr_inode_count()) is subject to failures so the callback has
to be able to report errors. And, that itself is problematic because
we can't afford to have errors in dquot_free_inode(). If you have
thoughts about how to address this please let me know.

Alternatively, I could try to make this patch less intrusive by
keeping the existing dquot_transfer() signature and add a new
dquot_transfer_usage() that accepts inode_usage as a parameter. What
do you think?