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Date: Mon, 08 Apr 2013 16:30:17 +0200
From: Robert Buhren <robert@robertbuhren.de>
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To: dsterba@suse.cz, linux-btrfs@vger.kernel.org
Subject: Re: "btrfs send" fails with having too many open fd's
References: <51613541.3080009@robertbuhren.de> <20130408131149.GC18193@twin.jikos.cz>
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On 08.04.2013 15:11, David Sterba wrote:
> On Sun, Apr 07, 2013 at 10:58:41AM +0200, Robert Buhren wrote:
>> "6,7226,15012711248,-;VFS: file-max limit 799969 reached"
>> Label: 'BACKUP'  uuid: 019e75e4-aa2e-495d-9711-28ef7150b1f3
>>      Total devices 2 FS bytes used 137.35GB
>> It takes a very long time before my system crashes (several hours) so i
>> wasn't able to monitor when exactly the fd's increase.
>> In the beginning "btrfs send" just opens less than 10 fd's, but at some
>> point "btrfs send" must open much more.
> It could be a case of
>
> 1) an endless loop, the file limit you've set is quite high (799969), I
> doubt that so many open fd's are needed at any point.
>
> 2) missing file close after in some error path
>
> The file's are open via
> send_write
>    open_cur_inode_file
>      dentry_open
>
> and closed from callbacks in close_cur_inode_file.
>
> Case 2 looks more realistic, but I don't have an idea what could go
> wrong.
>
> david
Do you have a suggestion on how to debug it further?

Regards,

Robert