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>

1 files changed, 20 insertions, 18 deletions

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 78a43b2e5c8e..8877adc45394 100644
--- 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);