From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Reiser Subject: Re: tail policy question Date: Thu, 13 Nov 2003 22:02:33 -0800 Message-ID: <3FB46FF9.2060402@namesys.com> References: <3FB22E06.9070500@namesys.com> <20031114170604.GQ1278@backtop.namesys.com> <3FB46424.4000300@namesys.com> <20031114172716.GU1278@backtop.namesys.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: <20031114172716.GU1278@backtop.namesys.com> List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Alex Zarochentsev Cc: Zhihui Zhang , reiserfs-list@namesys.com, vs@namesys.com Alex Zarochentsev wrote: >On Thu, Nov 13, 2003 at 09:12:04PM -0800, Hans Reiser wrote: > > >>Alex Zarochentsev wrote: >> >> >> >>>On Thu, Nov 13, 2003 at 01:34:07PM -0500, Zhihui Zhang wrote: >>> >>> >>> >>> >>>>Thanks for your and Alex's reply. I poke around a little bit more and >>>>find out that the mkfs.c does use ITEM_TAIL40_ID, which happens to have >>>>the same value as TAIL_ID (0x6) in the kernel file. >>>> >>>> >>>> >>>> >>>they are from different name spaces. >>> >>> >>> >>> >>> >>> >>>>However, I am confused >>>>when I see the following in plugin.h: >>>> >>>>PLUGIN_BY_ID(item_plugin, REISER4_ITEM_PLUGIN_TYPE, item); >>>>PLUGIN_BY_ID(tail_plugin, REISER4_TAIL_PLUGIN_TYPE, tail); >>>> >>>> >>>> >>>> >>>IFAIK above defines service functions for plugins of different types, >>>it does not define concrete plugins. tail_plugin_type should be named >>>as tail_policy_plugin for better understanding. >>> >>> >>> >>> >>> >>>>The item plugin has TAIL_ID if the item is of tail type. So what is the >>>>use of a separate tail_plugin? Plus, the tail_plugin has three IDs >>>>defined: NEVER, ALWAYS, and DEFAULT, none of which has a value of 0x6. My >>>>guess is that the item plugin for tails are used to manage tails (merge, >>>>split, read, write?), >>>> >>>> >>>> >>>> >>>yes >>> >>> >>> >>> >>> >>>>while the tail_plugin is used to decide if a >>>>conversion between tail format and extent format is needed. If so, the >>>>reiser4.h file should have: >>>> >>>>#define REISER4_TAIL_PLUGIN (DEFAULT_TAIL_ID) >>>> >>>>instead of >>>> >>>>#define REISER4_TAIL_PLUGIN (ALWAYS_TAIL_ID) >>>> >>>>Does this make sense? Please clarify this for me. Thanks. >>>> >>>> >>>> >>>> >>>what i would like to see: >>>rename *_TAIL_ID to *_TAIL_POLICY_ID >>>DEFAULT_TAIL_POLICY__ID renamed to SMART_TAIL_POLICY_ID >>> >>> >>> >>> >>16K_TAIL_POLICY is more informative.... >> >> > >I think digits cannot be at the first place. > > TAIL_16k_ID > > >>>#define REISER4_TAIL_POLICY_PLUGIN (one of SMART_TAIL_POLICY_ID >>>ALWAYS_TAIL_POLICY_ID, >>>NEVER_TAIL_POLICY_ID) >>> >>>Does it make things more clear? >>> >>>Thanks. >>> >>> >>> >>> >>-- >>Hans >> >> >> >> > > > -- Hans