Btrfs: fix unprotected system chunk array insertion

We didn't protect the system chunk array when we added a new
system chunk into it, it would cause the array be corrupted
if someone remove/add some system chunk into array at the same
time. Fix it by chunk lock.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 41da102cdcc0..9f22398d465f 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4054,10 +4054,13 @@ static int btrfs_add_system_chunk(struct btrfs_root *root,
         u32 array_size;
         u8 *ptr;
 
+        lock_chunks(root);
         array_size = btrfs_super_sys_array_size(super_copy);
         if (array_size + item_size + sizeof(disk_key)
-                        > BTRFS_SYSTEM_CHUNK_ARRAY_SIZE)
+                        > BTRFS_SYSTEM_CHUNK_ARRAY_SIZE) {
+                unlock_chunks(root);
                 return -EFBIG;
+        }
 
         ptr = super_copy->sys_chunk_array + array_size;
         btrfs_cpu_key_to_disk(&disk_key, key);
@@ -4066,6 +4069,8 @@ static int btrfs_add_system_chunk(struct btrfs_root *root,
         memcpy(ptr, chunk, item_size);
         item_size += sizeof(disk_key);
         btrfs_set_super_sys_array_size(super_copy, array_size + item_size);
+        unlock_chunks(root);
+
         return 0;
 }