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由 Mark Fasheh 提交于
During its tree walk, btrfs_drop_snapshot() will skip any shared subtrees it encounters. This is incorrect when we have qgroups turned on as those subtrees need to have their contents accounted. In particular, the case we're concerned with is when removing our snapshot root leaves the subtree with only one root reference. In those cases we need to find the last remaining root and add each extent in the subtree to the corresponding qgroup exclusive counts. This patch implements the shared subtree walk and a new qgroup operation, BTRFS_QGROUP_OPER_SUB_SUBTREE. When an operation of this type is encountered during qgroup accounting, we search for any root references to that extent and in the case that we find only one reference left, we go ahead and do the math on it's exclusive counts. Signed-off-by: NMark Fasheh <mfasheh@suse.de> Reviewed-by: NJosef Bacik <jbacik@fb.com> Signed-off-by: NChris Mason <clm@fb.com>
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