Btrfs: fix wrong disk size when writing super blocks

total_size will be changed when resizing a device, and disk_total_size
will be changed if resizing is successful. Meanwhile, the on-disk super
blocks of the previous transaction might not be updated. Considering
the consistency of the metadata in the previous transaction, We should
use the size in the previous transaction to check if the super block is
beyond the boundary of the device. Fix it.

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

1 files changed, 18 insertions, 0 deletions

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 72dc02e82945..7877b0fc6a8d 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -168,6 +168,8 @@ no_valid_dev_replace_entry_found:
                                         dev_replace->srcdev->total_bytes;
                                 dev_replace->tgtdev->disk_total_bytes =
                                         dev_replace->srcdev->disk_total_bytes;
+                                dev_replace->tgtdev->commit_total_bytes =
+                                        dev_replace->srcdev->commit_total_bytes;
                                 dev_replace->tgtdev->bytes_used =
                                         dev_replace->srcdev->bytes_used;
                         }
@@ -329,6 +331,20 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
             args->start.tgtdev_name[0] == '\0')
                 return -EINVAL;
 
+        /*
+         * Here we commit the transaction to make sure commit_total_bytes
+         * of all the devices are updated.
+         */
+        trans = btrfs_attach_transaction(root);
+        if (!IS_ERR(trans)) {
+                ret = btrfs_commit_transaction(trans, root);
+                if (ret)
+                        return ret;
+        } else if (PTR_ERR(trans) != -ENOENT) {
+                return PTR_ERR(trans);
+        }
+
+        /* the disk copy procedure reuses the scrub code */
         mutex_lock(&fs_info->volume_mutex);
         ret = btrfs_dev_replace_find_srcdev(root, args->start.srcdevid,
                                             args->start.srcdev_name,
@@ -539,6 +555,8 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
         tgt_device->total_bytes = src_device->total_bytes;
         tgt_device->disk_total_bytes = src_device->disk_total_bytes;
+        ASSERT(list_empty(&src_device->resized_list));
+        tgt_device->commit_total_bytes = src_device->commit_total_bytes;
         tgt_device->bytes_used = src_device->bytes_used;
         if (fs_info->sb->s_bdev == src_device->bdev)
                 fs_info->sb->s_bdev = tgt_device->bdev;