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>
(cherry picked from commit fe48a5c00f3c8087fc0a447caee2b5f9f97cf238)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 93ddc7756e093141fd61adf9beddea487eb1fc3d..ba239d4f10e739de56cc85a4dc3232d7ad472741 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4051,10 +4051,13 @@ 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);
@@ -4063,6 +4066,8 @@ 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;
 }