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Re: [Q] missing unused dentry in prune_dcache()? [message #7790 is a reply to message #7784]

Wed, 25 October 2006 13:51

David Howells
Messages: 44
Registered: October 2006

Member

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.

Acked-By: David Howells <dhowells@redhat.com>

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[Message index]

		[Q] missing unused dentry in prune_dcache()? By: vaverin on Wed, 25 October 2006 12:30
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Wed, 25 October 2006 13:58
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Wed, 25 October 2006 14:23
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Thu, 26 October 2006 11:36
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Thu, 26 October 2006 13:25
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Fri, 27 October 2006 08:05
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Fri, 27 October 2006 10:42
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Fri, 27 October 2006 11:50
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Fri, 27 October 2006 12:11
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Fri, 27 October 2006 13:47
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Fri, 27 October 2006 14:29
		Re: [Q] missing unused dentry in prune_dcache()? By: dev on Fri, 27 October 2006 14:34
		[PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: vaverin on Fri, 27 October 2006 14:05
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Andrew Morton on Fri, 27 October 2006 18:06
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: vaverin on Mon, 30 October 2006 14:24
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Eric Dumazet on Mon, 30 October 2006 15:08
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: dev on Mon, 30 October 2006 15:27
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Eric Dumazet on Mon, 30 October 2006 16:09
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: dev on Mon, 30 October 2006 15:06
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: David Chinner on Mon, 30 October 2006 04:24
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: dev on Mon, 30 October 2006 06:22
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Neil Brown on Tue, 31 October 2006 04:38
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: David Howells on Tue, 31 October 2006 10:40
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Neil Brown on Wed, 01 November 2006 06:32
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: vaverin on Wed, 01 November 2006 13:32
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Neil Brown on Tue, 14 November 2006 05:44
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: vaverin on Tue, 14 November 2006 06:12
		Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: vaverin on Tue, 31 October 2006 13:08
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: dev on Wed, 01 November 2006 10:48
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: Neil Brown on Tue, 14 November 2006 04:51
		Re: Re: [PATCH 2.6.19-rc3] VFS: per-sb dentry lru list By: David Howells on Tue, 14 November 2006 09:29
		[PATCH 2.6.19-rc3] VFS: missing unused dentry in prune_dcache() By: vaverin on Fri, 27 October 2006 13:42
		Re: [PATCH 2.6.19-rc3] VFS: missing unused dentry in prune_dcache() By: David Howells on Fri, 27 October 2006 14:24
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Wed, 25 October 2006 13:51
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Thu, 26 October 2006 11:49
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Thu, 26 October 2006 12:33
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Thu, 26 October 2006 13:23
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Thu, 26 October 2006 13:58
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Thu, 26 October 2006 14:07
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Fri, 27 October 2006 06:32
		Re: [Q] missing unused dentry in prune_dcache()? By: vaverin on Fri, 27 October 2006 06:50
		Re: [Q] missing unused dentry in prune_dcache()? By: David Howells on Fri, 27 October 2006 09:36
		[Q] missing ->d_delete() in shrink_dcache_for_umount()? By: vaverin on Tue, 31 October 2006 13:24
		Re: [Q] missing ->d_delete() in shrink_dcache_for_umount()? By: David Howells on Tue, 31 October 2006 15:06

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