linux-next/fs/jffs2/TODO

$Id: TODO,v 1.10 2002/09/09 16:31:21 dwmw2 Exp $

 - disable compression in commit_write()?
 - fine-tune the allocation / GC thresholds
 - chattr support - turning on/off and tuning compression per-inode
 - checkpointing (do we need this? scan is quite fast)
 - make the scan code populate real inodes so read_inode just after 
	mount doesn't have to read the flash twice for large files.
	Make this a per-inode option, changable with chattr, so you can
	decide which inodes should be in-core immediately after mount.
 - test, test, test

 - NAND flash support:
	- flush_wbuf using GC to fill it, don't just pad.
	- Deal with write errors. Data don't get lost - we just have to write 
	  the affected node(s) out again somewhere else.
	- make fsync flush only if actually required
	- make sys_sync() work.
	- reboot notifier
	- timed flush of old wbuf
	- fix magical second arg of jffs2_flush_wbuf(). Split into two or more functions instead.


 - Optimisations:
   - Stop GC from decompressing and immediately recompressing nodes which could
     just be copied intact. (We now keep track of REF_PRISTINE flag. Easy now.)
   - Furthermore, in the case where it could be copied intact we don't even need
     to call iget() for it -- if we use (raw_node_raw->flash_offset & 2) as a flag
     to show a node can be copied intact and it's _not_ in icache, we could just do
     it, fix up the next_in_ino list and move on. We would need a way to find out
     _whether_ it's in icache though -- if it's in icache we also need to do the 
     fragment lists, etc. P'raps a flag or pointer in the jffs2_inode_cache could
     help. (We have half of this now.)
   - Stop keeping name in-core with struct jffs2_full_dirent. If we keep the hash in 
     the full dirent, we only need to go to the flash in lookup() when we think we've
     got a match, and in readdir(). 
   - Doubly-linked next_in_ino list to allow us to free obsoleted raw_node_refs immediately?
   - Remove totlen from jffs2_raw_node_ref? Need to have totlen passed into
	jffs2_mark_node_obsolete(). Can all callers work it out?
   - Remove size from jffs2_raw_node_frag.
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! 2005-04-17 06:20:36 +08:00			$Id: TODO,v 1.10 2002/09/09 16:31:21 dwmw2 Exp $

			`- disable compression in commit_write()?`
			`- fine-tune the allocation / GC thresholds`
			`- chattr support - turning on/off and tuning compression per-inode`
			`- checkpointing (do we need this? scan is quite fast)`
			`- make the scan code populate real inodes so read_inode just after`
			`mount doesn't have to read the flash twice for large files.`
			`Make this a per-inode option, changable with chattr, so you can`
			`decide which inodes should be in-core immediately after mount.`
			`- test, test, test`

			`- NAND flash support:`
			`- flush_wbuf using GC to fill it, don't just pad.`
			`- Deal with write errors. Data don't get lost - we just have to write`
			`the affected node(s) out again somewhere else.`
			`- make fsync flush only if actually required`
			`- make sys_sync() work.`
			`- reboot notifier`
			`- timed flush of old wbuf`
			`- fix magical second arg of jffs2_flush_wbuf(). Split into two or more functions instead.`


			`- Optimisations:`
			`- Stop GC from decompressing and immediately recompressing nodes which could`
			`just be copied intact. (We now keep track of REF_PRISTINE flag. Easy now.)`
			`- Furthermore, in the case where it could be copied intact we don't even need`
			`to call iget() for it -- if we use (raw_node_raw->flash_offset & 2) as a flag`
			`to show a node can be copied intact and it's _not_ in icache, we could just do`
			`it, fix up the next_in_ino list and move on. We would need a way to find out`
			`_whether_ it's in icache though -- if it's in icache we also need to do the`
			`fragment lists, etc. P'raps a flag or pointer in the jffs2_inode_cache could`
			`help. (We have half of this now.)`
			`- Stop keeping name in-core with struct jffs2_full_dirent. If we keep the hash in`
			`the full dirent, we only need to go to the flash in lookup() when we think we've`
			`got a match, and in readdir().`
			`- Doubly-linked next_in_ino list to allow us to free obsoleted raw_node_refs immediately?`
			`- Remove totlen from jffs2_raw_node_ref? Need to have totlen passed into`
			`jffs2_mark_node_obsolete(). Can all callers work it out?`
			`- Remove size from jffs2_raw_node_frag.`