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| author | Liu Bo <bo.li.liu@oracle.com> | 2013-10-30 13:25:24 +0800 |
|---|---|---|
| committer | Chris Mason <chris.mason@fusionio.com> | 2013-11-11 22:11:07 -0500 |
| commit | 48ec47364b6d493f0a9cdc116977bf3f34e5c3ec (patch) | |
| tree | 455b5cc2c7d0014bc23e469445f2011d7ce14a58 /fs/btrfs/backref.c | |
| parent | 6f519564d7d978c00351d9ab6abac3deeac31621 (diff) | |
| download | blackbird-op-linux-48ec47364b6d493f0a9cdc116977bf3f34e5c3ec.tar.gz blackbird-op-linux-48ec47364b6d493f0a9cdc116977bf3f34e5c3ec.zip | |
Btrfs: fix a crash when running balance and defrag concurrently
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@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Diffstat (limited to 'fs/btrfs/backref.c')
| -rw-r--r-- | fs/btrfs/backref.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index 721936a5b2ca..30d24cfb45d4 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -185,6 +185,9 @@ static int __add_prelim_ref(struct list_head *head, u64 root_id, { 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; |
