[Cluster-devel] [PATCH 10/12] gfs2: Generalize truncate code

[Bob Peterson <rpeterso@redhat.com>]

Hi,

----- Original Message -----
| Pull the code for computing the range of metapointers to iterate out of
| gfs2_metapath_ra (for readahead), sweep_bh_for_rgrps (for deallocating
| metapointers within a block), and trunc_dealloc (for walking the
| metadata tree).
| 
| In sweep_bh_for_rgrps, move the code for looking up the resource group
| descriptor of the current resource group out of the inner loop.  The
| metatype check moves to trunc_dealloc.
| 
| Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
| ---
(snip)
| @@ -1229,7 +1216,11 @@ static int sweep_bh_for_rgrps(struct gfs2_inode *ip,
| struct gfs2_holder *rd_gh,
|  					    outside the rgrp we just processed,
|  					    do it all over again. */
|  		if (current->journal_info) {
| -			struct buffer_head *dibh = mp->mp_bh[0];
| +			struct buffer_head *dibh;
| +
| +			ret = gfs2_meta_inode_buffer(ip, &dibh);
| +			if (ret)
| +				goto out;
(snip)...
| +			brelse(dibh);

I don't understand why you prefer to use gfs2_meta_inode_buffer here
instead of just using the copy we already have in the metapath.
It seems to me this method would be a lot less efficient.
Can you explain?

Regards,

Bob Peterson
Red Hat File Systems