btrfs: send: handle unexpected data in header buffer in begin_cmd()

Change BUG_ON to a proper error handling in the unlikely case of seeing
data when the command is started. This is supposed to be reset when the
command is finished (send_cmd, send_encoded_extent).

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 597ecea550ed844d4a5d2c0013b197959f5a34b0..8c3ca4a5d923b061d4bf6c512a7685b3edbc3afd 100644 (file)
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -776,7 +776,12 @@ static int begin_cmd(struct send_ctx *sctx, int cmd)
        if (WARN_ON(!sctx->send_buf))
                return -EINVAL;
 
-       BUG_ON(sctx->send_size);
+       if (unlikely(sctx->send_size != 0)) {
+               btrfs_err(sctx->send_root->fs_info,
+                         "send: command header buffer not empty cmd %d offset %llu",
+                         cmd, sctx->send_off);
+               return -EINVAL;
+       }
 
        sctx->send_size += sizeof(*hdr);
        hdr = (struct btrfs_cmd_header *)sctx->send_buf;