Hi Andrew. Thank you for your useful comment. Andrew Morton wrote: > (added linux-fsdevel) > > On Thu, 23 Oct 2008 17:41:01 +0900 > Toshiyuki Okajima <toshi.okajima@xxxxxxxxxxxxxx> wrote: <SNIP> > > I managed to build a shrinker callback function for the journal_head slab cache. > > > This code size is less than before but the logic of it seems to be more complex > > > than before. > > > However, I haven't got any troubles while I am testing some easy load operations > > > on the fixed kernel. > > > But I think a system may hang up if concurrently several journal_head shrinker > > > are executed. > > > So, I will retry to build more appropriate fix. > > yeah, that's not very pretty either, is it? Yes... I realized fixing only within buffer_head or jbd needs a more complex code. > > > Please give me comments if you have a nicer idea. > Stepping back a bit... > > The basic problem is, I believe, that some client of the blockdev > (ext3) is adding metadata to the blockdev's data structures > (buffer_heads) but we have no means by which the blockdev code can call > back into that client requesting that the metadata be released, yes? Yes. > We can fix the problem which you've identified by adding a means for > the blockdev code (def_blk_aops.releasepage()) to call back into ext3, > yes? Yes. At first, I tried to fix by using only filesystem approach. - ver.1: fixing in buffer_head - ver.2: adding shrinker of journal_head (for releasing buffer_head) But these approaches become complex code. So, we should fix the essence of the problem. > If so, how do we do that? > > I seem to recall that there's code somewhere in the tree which does > things like taking a copy of bdev->address_space_operations and > reinstalling that, and overwriting selected fields, and then arranging > somehow for the old value to be reinstalled when the client releases > the blockdev. That's plain nasty. uh-huh. I try to fix this problem again by using your approach, blkdev_register_releasepage/blkdev_unregister_releasepage(). Best Regards, Toshiyuki Okajima -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
