Messages in this thread |  | | | From | David Howells <> | | Subject | Re: [Q] missing unused dentry in prune_dcache()? | | Date | Wed, 25 Oct 2006 14:51:04 +0100 |
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Vasily Averin <vvs@sw.ru> wrote:
> # If prune_dcache finds a dentry that it cannot free, it leaves it where it > # is (at the tail of the list) and exits, on the assumption that some other > # thread will be removing that dentry soon. > > However as far as I see this comment is not correct: when we cannot take > s_umount rw_semaphore (for example because it was taken in do_remount) this > dentry is already extracted from dentry_unused list and we do not add it into > the list again.
You would seem to be correct.
> Therefore dentry will not be found by prune_dcache() and shrink_dcache_sb() > and will leave in memory very long time until the partition will be > unmounted.
And here too:-/
> Am I probably err?
Unfortunately not. I wonder if remount should be getting a writelock on the s_umount sem, but I don't see why not. grab_super() also gets a writelock on it, and so that could cause problems too.
shrink_dcache_for_umount_subtree() doesn't care because it doesn't scan the dcache_unused list, but as you say, other things are affected.
> The patch adds this dentry into tail of the dentry_unused list.
I think that's reasonable. I wonder if we can avoid removing it from the list in the first place, but I suspect it's less optimal.
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