btrfs: check balance of send_in_progress

Warn if the balance goes below zero, which appears to be unlikely
though. Otherwise cleans up the code a bit.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 78a43b2e5c8e2e42459a91c7b82be8fe71ff0787..8877adc4539433a1ce0b9d382aad5cb1d91cdbb0 100644 (file)
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -4725,6 +4725,21 @@ out:
        return ret;
 }
 
+static void btrfs_root_dec_send_in_progress(struct btrfs_root* root)
+{
+       spin_lock(&root->root_item_lock);
+       root->send_in_progress--;
+       /*
+        * Not much left to do, we don't know why it's unbalanced and
+        * can't blindly reset it to 0.
+        */
+       if (root->send_in_progress < 0)
+               btrfs_err(root->fs_info,
+                       "send_in_progres unbalanced %d root %llu\n",
+                       root->send_in_progress, root->root_key.objectid);
+       spin_unlock(&root->root_item_lock);
+}
+
 long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
 {
        int ret = 0;
@@ -4942,24 +4957,11 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
        }
 
 out:
-       for (i = 0; sctx && i < clone_sources_to_rollback; i++) {
-               struct btrfs_root *r = sctx->clone_roots[i].root;
-
-               spin_lock(&r->root_item_lock);
-               r->send_in_progress--;
-               spin_unlock(&r->root_item_lock);
-       }
-       if (sctx && !IS_ERR_OR_NULL(sctx->parent_root)) {
-               struct btrfs_root *r = sctx->parent_root;
-
-               spin_lock(&r->root_item_lock);
-               r->send_in_progress--;
-               spin_unlock(&r->root_item_lock);
-       }
-
-       spin_lock(&send_root->root_item_lock);
-       send_root->send_in_progress--;
-       spin_unlock(&send_root->root_item_lock);
+       for (i = 0; sctx && i < clone_sources_to_rollback; i++)
+               btrfs_root_dec_send_in_progress(sctx->clone_roots[i].root);
+       if (sctx && !IS_ERR_OR_NULL(sctx->parent_root))
+               btrfs_root_dec_send_in_progress(sctx->parent_root);
+       btrfs_root_dec_send_in_progress(send_root);
 
        kfree(arg);
        vfree(clone_sources_tmp);