Re: [PATCH] Btrfs: MOD_LOG_KEY_REMOVE_WHILE_MOVING never change node's nritems

[Jan Schmidt <list.btrfs@jan-o-sch.net>]

On Thu, October 18, 2012 at 09:32 (+0200), Liu Bo wrote:
> Key MOD_LOG_KEY_REMOVE_WHILE_MOVING means that we're doing memmove inside
> an extent buffer node, and the node's number of items remains unchanged,
> so we don't need to increment node's number of items during rewinding,
> otherwise we may get an node larger than leafsize and cause general protection
> errors later.

This patch triggers the following bug on when running fsmark on a quota enabled
file system:

1153                 case MOD_LOG_KEY_REPLACE:
1154                         BUG_ON(tm->slot >= n);

MOD_LOG_KEY_REMOVE_WHILE_MOVING elements are added by tree_mod_log_insert_move
when dst_slot < src_slot, thus we're reducing the number of elements in the
buffer, thus replaying adds those elements.

-Jan