Btrfs: fix task hang under heavy compressed write

[cascardo/linux.git] / fs / btrfs / reada.c

diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index 30947f9..20408c6 100644 (file)
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -428,8 +428,13 @@ static struct reada_extent *reada_find_extent(struct btrfs_root *root,
                        continue;
                }
                if (!dev->bdev) {
-                       /* cannot read ahead on missing device */
-                       continue;
+                       /*
+                        * cannot read ahead on missing device, but for RAID5/6,
+                        * REQ_GET_READ_MIRRORS return 1. So don't skip missing
+                        * device for such case.
+                        */
+                       if (nzones > 1)
+                               continue;
                }
                if (dev_replace_is_ongoing &&
                    dev == fs_info->dev_replace.tgtdev) {
@@ -793,7 +798,8 @@ static void reada_start_machine(struct btrfs_fs_info *fs_info)
                /* FIXME we cannot handle this properly right now */
                BUG();
        }
-       btrfs_init_work(&rmw->work, reada_start_machine_worker, NULL, NULL);
+       btrfs_init_work(&rmw->work, btrfs_readahead_helper,
+                       reada_start_machine_worker, NULL, NULL);
        rmw->fs_info = fs_info;
 
        btrfs_queue_work(fs_info->readahead_workers, &rmw->work);