JFFS2 Request For Testing.

JFFS2 Request For Testing.

[David Woodhouse]

I've got JFFS2 to the stage where it's passing dbench runs and the GC looks
reasonably OK. The design is basically the result of the discussion we were
having a few weeks ago (on the jffs-dev list) - I don't think anything's
particularly different from what we were talking about. 

Please take a look and comment, and preferably test it. Instructions on 
getting it from CVS are on http://www.linux-mtd.infradead.org/ and it'll 
turn up in ftp.uk.linux.org:/pub/people/dwmw2/mtd/cvs at about 11pm tonight.

For easy testing on a PC, turn on CONFIG_MTD_MTDRAM and test it on ram, 
instead of real flash.

There's free beer for the first person who tells me why I need the 
invalidate_inode_pages() in jffs2_file_release() when no other filesystem 
seems to need it, or why it sometimes gets stuck on unmount, in 
__wait_on_page() called from invalidate_inodes(). I suspect they're 
related, and it's a stupid bug on my part.

There's also a free beer for whoever provides mkfs.jffs2.

Aside from the bugs, there's a few things left to tidy up...

 - background GC
 - fine-tune the allocation / GC thresholds
 - More optimal compression. Currently it's optimised for mips32 code.
 - chattr support - turning on/off and tuning compression per-inode
 - checkpointing
 - making the scan code populate real inodes so read_inode just after 
	mount doesn't have to read the flash twice for large files.
 - disable compression in commit_write()?
 - stop it depending on a block device. mount(8) needs a change for this.
 - test, test, test
 - make it work on NAND flash. We need to know when we can GC
	deletion dirents, etc. And think about holes/truncation. It can
	all be done reasonably simply, but it need implementing.
 - NAND flash will require new dirent/dnode structures on the medium with
	ECC data in rather than just the CRC we're using ATM.
 - more?

--
dwmw2




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