• Qu Wenruo's avatar
    btrfs: require only sector size alignment for parent eb bytenr · a6fdfac3
    Qu Wenruo authored
    commit ea57788e upstream.
    
    [BUG]
    A completely sane converted fs will cause kernel warning at balance
    time:
    
      [ 1557.188633] BTRFS info (device sda7): relocating block group 8162107392 flags data
      [ 1563.358078] BTRFS info (device sda7): found 11722 extents
      [ 1563.358277] BTRFS info (device sda7): leaf 7989321728 gen 95 total ptrs 213 free space 3458 owner 2
      [ 1563.358280] 	item 0 key (7984947200 169 0) itemoff 16250 itemsize 33
      [ 1563.358281] 		extent refs 1 gen 90 flags 2
      [ 1563.358282] 		ref#0: tree block backref root 4
      [ 1563.358285] 	item 1 key (7985602560 169 0) itemoff 16217 itemsize 33
      [ 1563.358286] 		extent refs 1 gen 93 flags 258
      [ 1563.358287] 		ref#0: shared block backref parent 7985602560
      [ 1563.358288] 			(parent 7985602560 is NOT ALIGNED to nodesize 16384)
      [ 1563.358290] 	item 2 key (7985635328 169 0) itemoff 16184 itemsize 33
      ...
      [ 1563.358995] BTRFS error (device sda7): eb 7989321728 invalid extent inline ref type 182
      [ 1563.358996] ------------[ cut here ]------------
      [ 1563.359005] WARNING: CPU: 14 PID: 2930 at 0xffffffff9f231766
    
    Then with transaction abort, and obviously failed to balance the fs.
    
    [CAUSE]
    That mentioned inline ref type 182 is completely sane, it's
    BTRFS_SHARED_BLOCK_REF_KEY, it's some extra check making kernel to
    believe it's invalid.
    
    Commit 64ecdb64 ("Btrfs: add one more sanity check for shared ref
    type") introduced extra checks for backref type.
    
    One of the requirement is, parent bytenr must be aligned to node size,
    which is not correct.
    
    One example is like this:
    
    0	1G  1G+4K		2G 2G+4K
    	|   |///////////////////|//|  <- A chunk starts at 1G+4K
                |   |	<- A tree block get reserved at bytenr 1G+4K
    
    Then we have a valid tree block at bytenr 1G+4K, but not aligned to
    nodesize (16K).
    
    Such chunk is not ideal, but current kernel can handle it pretty well.
    We may warn about such tree block in the future, but should not reject
    them.
    
    [FIX]
    Change the alignment requirement from node size alignment to sector size
    alignment.
    
    Also, to make our lives a little easier, also output @iref when
    btrfs_get_extent_inline_ref_type() failed, so we can locate the item
    easier.
    
    Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=205475
    Fixes: 64ecdb64 ("Btrfs: add one more sanity check for shared ref type")
    CC: stable@vger.kernel.org # 4.14+
    Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
    Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
    [ update comments and messages ]
    Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    a6fdfac3
print-tree.c 11.5 KB