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List:       linux-btrfs
Subject:    Re: [PATCH] btrfs-progs: repair: Trickle down EEXISTS while freeing
From:       Goldwyn Rodrigues <rgoldwyn () suse ! de>
Date:       2016-10-31 18:43:20
Message-ID: 211e0109-1ce7-44fd-1e73-a1f1a96c44e2 () suse ! de
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Hi David,

On 10/28/2016 09:42 AM, David Sterba wrote:
> On Thu, Oct 27, 2016 at 01:05:08PM -0500, Goldwyn Rodrigues wrote:
>> While deleting pending extents, we insert extents to the 
>> extent_tree. However, because of corruption, this might already be
>> freed. We trickle the EEXISTS error and let the caller decide what
>> needs to be done with it. In this case, ignore, so the repair may
>> proceed.
>> 
>> The primary motivation of this is to resolve this BUG_ON: 
>> extent-tree.c:2731: alloc_reserved_tree_block: Assertion `ret`
>> failed, value 0
>> 
>> #2  assert_trace (val=0, line=2728, func=0x489510 <__func__.11558>
>> "alloc_reserved_tree_block", filename=0x489065 "extent-tree.c",
>> assertion=0x48cfb5 "ret") at kerncompat.h:102 #3
>> alloc_reserved_tree_block (trans=trans@entry=0x7e7240,
>> root=root@entry=0x6a88a0, root_objectid=2, generation=175654,
>> flags=0, key=key@entry=0x2bc5c70, level=0,
>> ins=ins@entry=0x7fffffffcf30) at extent-tree.c:2728 #4
>> finish_current_insert (trans=trans@entry=0x7e7240,
>> extent_root=extent_root@entry=0x6a88a0) at extent-tree.c:2108 #5
>> __free_extent (trans=trans@entry=0x7e7240,
>> root=root@entry=0x6a88a0, bytenr=57127387136, num_bytes=<optimized
>> out>, parent=parent@entry=0, root_objectid=<optimized out>,
>> owner_objectid=0, owner_offset=owner_offset@entry=0,
>> refs_to_drop=refs_to_drop@entry=1) at extent-tree.c:2410 #6
>> del_pending_extents (trans=trans@entry=0x7e7240,
>> extent_root=0x6a88a0) at extent-tree.c:2448
> 
> Do you have a reproducer for that?

>> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> Applied, thanks.
> 

While working on a reproducer (and further testing), I found this leaves
the tree in a worse condition than before. Please leave this out for now.


-- 
Goldwyn
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