A missing branch in btrfs_get_fs_root() is making dedupe_root read from
disk, and REF_COWS bit set.
This makes btrfs balance treating dedupe_root as fs root, and reusing the
old dedupe root bytenr to drop tree ref, causing the following kernel
warning after metadata balancing:
BTRFS error (device sdb6): unable to find ref byte nr 29736960 parent 0
root 11 owner 0 offset 0
------------[ cut here ]------------
WARNING: CPU: 1 PID: 19113 at fs/btrfs/extent-tree.c:6636
__btrfs_free_extent.isra.66+0xb6d/0xd20 [btrfs]()
BTRFS: Transaction aborted (error -2)
Modules linked in: btrfs(O) xor zlib_deflate raid6_pq xfs [last
unloaded: btrfs]
CPU: 1 PID: 19113 Comm: btrfs Tainted: G W O 4.5.0-rc5+ #2
Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox
12/01/2006
0000000000000000 ffff880035b0ba18 ffffffff813771ff ffff880035b0ba60
ffffffffa06a810a ffff880035b0ba50 ffffffff810bcb81 ffff88003c45c528
0000000001c5c000 00000000fffffffe ffff88003dc8c520 0000000000000000
Call Trace:
[<ffffffff813771ff>] dump_stack+0x67/0x98
[<ffffffff810bcb81>] warn_slowpath_common+0x81/0xc0
[<ffffffff810bcc07>] warn_slowpath_fmt+0x47/0x50
[<ffffffffa06028fd>] __btrfs_free_extent.isra.66+0xb6d/0xd20 [btrfs]
[<ffffffffa0606d4d>] __btrfs_run_delayed_refs.constprop.71+0x96d/0x1560
[btrfs]
[<ffffffff81202ad9>] ? cmpxchg_double_slab.isra.68+0x149/0x160
[<ffffffff81106a1d>] ? trace_hardirqs_on+0xd/0x10
[<ffffffffa060a5ce>] btrfs_run_delayed_refs+0x8e/0x2d0 [btrfs]
[<ffffffffa06209fe>] btrfs_commit_transaction+0x3e/0xb50 [btrfs]
[<ffffffffa069f26e>] ? btrfs_dedupe_disable+0x28e/0x2c0 [btrfs]
[<ffffffff812035c3>] ? kfree+0x223/0x270
[<ffffffffa069f27a>] btrfs_dedupe_disable+0x29a/0x2c0 [btrfs]
[<ffffffffa065e403>] btrfs_ioctl+0x2363/0x2a40 [btrfs]
[<ffffffff8116b12a>] ? __audit_syscall_entry+0xaa/0xf0
[<ffffffff81137ce6>] ? current_kernel_time64+0x56/0xa0
[<ffffffff8122080e>] do_vfs_ioctl+0x8e/0x690
[<ffffffff8116b12a>] ? __audit_syscall_entry+0xaa/0xf0
[<ffffffff8122c181>] ? __fget_light+0x61/0x90
[<ffffffff81220e84>] SyS_ioctl+0x74/0x80
[<ffffffff8180ad57>] entry_SYSCALL_64_fastpath+0x12/0x6f
---[ end trace 618d5a5bc21d6a7c ]---
Fix it by adding corresponding branch for btrfs_get_fs_root().
Reported-by: Satoru Takeuchi <takeuchi_sat...@jp.fujitsu.com>
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
fs/btrfs/disk-io.c | 5 +++++
fs/btrfs/relocation.c | 3 ++-
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 44d098d..ec9fff3 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1679,6 +1679,11 @@ struct btrfs_root *btrfs_get_fs_root(struct
btrfs_fs_info *fs_info,
if (location->objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
return fs_info->free_space_root ? fs_info->free_space_root :
ERR_PTR(-ENOENT);
+ if (location->objectid == BTRFS_DEDUPE_TREE_OBJECTID) {
+ if (fs_info->dedupe_enabled && fs_info->dedupe_info)
+ return fs_info->dedupe_info->dedupe_root;
+ return ERR_PTR(-ENOENT);
+ }
again:
root = btrfs_lookup_fs_root(fs_info, location->objectid);
if (root) {
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 71a5cd0..74fd5d9 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -577,7 +577,8 @@ static int is_cowonly_root(u64 root_objectid)
root_objectid == BTRFS_CSUM_TREE_OBJECTID ||
root_objectid == BTRFS_UUID_TREE_OBJECTID ||
root_objectid == BTRFS_QUOTA_TREE_OBJECTID ||
- root_objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
+ root_objectid == BTRFS_FREE_SPACE_TREE_OBJECTID ||
+ root_objectid == BTRFS_DEDUPE_TREE_OBJECTID)
return 1;
return 0;
}
--
2.7.3
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