Patch "Btrfs: only do the tree_mod_log_free_eb if this is our last" has been added to the 3.9-stable tree

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This is a note to let you know that I've just added the patch titled

    Btrfs: only do the tree_mod_log_free_eb if this is our last

to the 3.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     btrfs-only-do-the-tree_mod_log_free_eb-if-this-is-our-last.patch
and it can be found in the queue-3.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 7fb7d76f96bfcbea25007d190ba828b18e13d29d Mon Sep 17 00:00:00 2001
From: Josef Bacik <jbacik@xxxxxxxxxxxx>
Date: Mon, 1 Jul 2013 16:10:16 -0400
Subject: Btrfs: only do the tree_mod_log_free_eb if this is our last
 ref

From: Josef Bacik <jbacik@xxxxxxxxxxxx>

commit 7fb7d76f96bfcbea25007d190ba828b18e13d29d upstream.

There is another bug in the tree mod log stuff in that we're calling
tree_mod_log_free_eb every single time a block is cow'ed.  The problem with this
is that if this block is shared by multiple snapshots we will call this multiple
times per block, so if we go to rewind the mod log for this block we'll BUG_ON()
in __tree_mod_log_rewind because we try to rewind a free twice.  We only want to
call tree_mod_log_free_eb if we are actually freeing the block.  With this patch
I no longer hit the panic in __tree_mod_log_rewind.  Thanks,

Reviewed-by: Jan Schmidt <list.btrfs@xxxxxxxxxxxxx>
Signed-off-by: Josef Bacik <jbacik@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/btrfs/ctree.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1049,7 +1049,8 @@ static noinline int __btrfs_cow_block(st
 		btrfs_set_node_ptr_generation(parent, parent_slot,
 					      trans->transid);
 		btrfs_mark_buffer_dirty(parent);
-		tree_mod_log_free_eb(root->fs_info, buf);
+		if (last_ref)
+			tree_mod_log_free_eb(root->fs_info, buf);
 		btrfs_free_tree_block(trans, root, buf, parent_start,
 				      last_ref);
 	}


Patches currently in stable-queue which might be from jbacik@xxxxxxxxxxxx are

queue-3.9/btrfs-fix-estale-with-btrfs-send.patch
queue-3.9/btrfs-only-do-the-tree_mod_log_free_eb-if-this-is-our-last.patch
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