This is a note to let you know that I've just added the patch titled
Btrfs: fix a crash when running balance and defrag concurrently
to the 3.12-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-fix-a-crash-when-running-balance-and-defrag-concurrently.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 48ec47364b6d493f0a9cdc116977bf3f34e5c3ec Mon Sep 17 00:00:00 2001
From: Liu Bo <bo.li.liu@xxxxxxxxxx>
Date: Wed, 30 Oct 2013 13:25:24 +0800
Subject: Btrfs: fix a crash when running balance and defrag concurrently
From: Liu Bo <bo.li.liu@xxxxxxxxxx>
commit 48ec47364b6d493f0a9cdc116977bf3f34e5c3ec upstream.
Running balance and defrag concurrently can end up with a crash:
kernel BUG at fs/btrfs/relocation.c:4528!
RIP: 0010:[<ffffffffa01ac33b>] [<ffffffffa01ac33b>] btrfs_reloc_cow_block+ 0x1eb/0x230 [btrfs]
Call Trace:
[<ffffffffa01398c1>] ? update_ref_for_cow+0x241/0x380 [btrfs]
[<ffffffffa0180bad>] ? copy_extent_buffer+0xad/0x110 [btrfs]
[<ffffffffa0139da1>] __btrfs_cow_block+0x3a1/0x520 [btrfs]
[<ffffffffa013a0b6>] btrfs_cow_block+0x116/0x1b0 [btrfs]
[<ffffffffa013ddad>] btrfs_search_slot+0x43d/0x970 [btrfs]
[<ffffffffa0153c57>] btrfs_lookup_file_extent+0x37/0x40 [btrfs]
[<ffffffffa0172a5e>] __btrfs_drop_extents+0x11e/0xae0 [btrfs]
[<ffffffffa013b3fd>] ? generic_bin_search.constprop.39+0x8d/0x1a0 [btrfs]
[<ffffffff8117d14a>] ? kmem_cache_alloc+0x1da/0x200
[<ffffffffa0138e7a>] ? btrfs_alloc_path+0x1a/0x20 [btrfs]
[<ffffffffa0173ef0>] btrfs_drop_extents+0x60/0x90 [btrfs]
[<ffffffffa016b24d>] relink_extent_backref+0x2ed/0x780 [btrfs]
[<ffffffffa0162fe0>] ? btrfs_submit_bio_hook+0x1e0/0x1e0 [btrfs]
[<ffffffffa01b8ed7>] ? iterate_inodes_from_logical+0x87/0xa0 [btrfs]
[<ffffffffa016b909>] btrfs_finish_ordered_io+0x229/0xac0 [btrfs]
[<ffffffffa016c3b5>] finish_ordered_fn+0x15/0x20 [btrfs]
[<ffffffffa018cbe5>] worker_loop+0x125/0x4e0 [btrfs]
[<ffffffffa018cac0>] ? btrfs_queue_worker+0x300/0x300 [btrfs]
[<ffffffff81075ea0>] kthread+0xc0/0xd0
[<ffffffff81075de0>] ? insert_kthread_work+0x40/0x40
[<ffffffff8164796c>] ret_from_fork+0x7c/0xb0
[<ffffffff81075de0>] ? insert_kthread_work+0x40/0x40
----------------------------------------------------------------------
It turns out to be that balance operation will bump root's @last_snapshot,
which enables snapshot-aware defrag path, and backref walking stuff will
find data reloc tree as refs' parent, and hit the BUG_ON() during COW.
As data reloc tree's data is just for relocation purpose, and will be deleted right
after relocation is done, it's unnecessary to walk those refs belonged to data reloc
tree, it'd be better to skip them.
Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
Signed-off-by: Josef Bacik <jbacik@xxxxxxxxxxxx>
Signed-off-by: Chris Mason <chris.mason@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/backref.c | 3 +++
1 file changed, 3 insertions(+)
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -185,6 +185,9 @@ static int __add_prelim_ref(struct list_
{
struct __prelim_ref *ref;
+ if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
+ return 0;
+
ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
if (!ref)
return -ENOMEM;
Patches currently in stable-queue which might be from bo.li.liu@xxxxxxxxxx are
queue-3.12/btrfs-fix-memory-leak-of-chunks-extent-map.patch
queue-3.12/btrfs-fix-lockdep-error-in-async-commit.patch
queue-3.12/btrfs-do-not-run-snapshot-aware-defragment-on-error.patch
queue-3.12/btrfs-fix-a-crash-when-running-balance-and-defrag-concurrently.patch
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