From: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Date: Wed, 11 Dec 2013 11:29:51 +0000 (+0800)
Subject: Btrfs: fix an oops when doing balance relocation
X-Git-Tag: v3.13-rc4~21^2~3
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c974c4642fee8c58239c7753d0bf548b23799923;p=pandora-kernel.git

Btrfs: fix an oops when doing balance relocation

I hit an oops when inserting reloc root into @reloc_root_tree(it can be
easily triggered when forcing cow for relocation root)

[  866.494539]  [<ffffffffa0499579>] btrfs_init_reloc_root+0x79/0xb0 [btrfs]
[  866.495321]  [<ffffffffa044c240>] record_root_in_trans+0xb0/0x110 [btrfs]
[  866.496109]  [<ffffffffa044d758>] btrfs_record_root_in_trans+0x48/0x80 [btrfs]
[  866.496908]  [<ffffffffa0494da8>] select_reloc_root+0xa8/0x210 [btrfs]
[  866.497703]  [<ffffffffa0495c8a>] do_relocation+0x16a/0x540 [btrfs]

This is because reloc root inserted into @reloc_root_tree is not within one
transaction,reloc root may be cowed and root block bytenr will be reused then
oops happens.We should update reloc root in @reloc_root_tree when cow reloc
root node, fix it.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
---

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