Re: [PATCH 00/11] reiserfs: xattr rework

[Jeff Mahoney <jeffm@suse.com>]

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Jan Kara wrote:
>   You are right that the quota code and xattrs need to do the same thing.
> We only need to do slight interface changes (currently functions take a
> superblock and a type and pick appropriate quota inode themselves) and
> function renaming. I would vote for renaming the s_op->quota_{read,write}
> to s_op->internal_{read,write} and pass appropriate inode directly from
> the quota code. The only thing I'm not sure about is how to deal with the
> journaling mode - quota code either uses data journaling or just ordered
> mode depending on mount options (journaled / non-journaled quota). So we
> probably also need to pass the journaling mode to the write function.
>   BTW: note that using these functions bypassing page cache means that
> userspace really should not touch these files. It is asking for data
> corruption. Quota code does during quotaon sync the quota inode and
> set it as immutable to prevent accidents. Also during quotaoff it flushes
> the page cache of the inode so that userspace is able to see the changes
> made by kernel. I guess something similar will be needed for xattrs too.

If you feel that changing the entire quota system to reflect the change
is a good plan, that's your call. Personally, I'd like to keep the
patches as small as possible, but if you think there is a need for
internal_{read,write} elsewhere, I wouldn't object.

The data journaling mode can be set as a flag associated with the inode.
 Currently, i_data_log is set in REISERFS_I(inode)->i_flags. I add
i_data_ordered in one of my later patches. They can be tested easily
with reiserfs_file_data_{log,ordered}. There's no reason that one
couldn't be moved up and made a prerequisite for the first patch.

There is one difference between quota files and xattrs: The quota files
are visible to userspace, xattrs are completely hidden. There's nothing
needed to flush anything to the page cache.

I'll work up a patch locally and do some testing.

- -Jeff

- --
Jeff Mahoney
SUSE Labs
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