Btrfs: fix race between scrub and block group deletion

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

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 6b3fd51..68af316 100644 (file)
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -3432,7 +3432,9 @@ out:
 static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
                                          struct btrfs_device *scrub_dev,
                                          u64 chunk_offset, u64 length,
-                                         u64 dev_offset, int is_dev_replace)
+                                         u64 dev_offset,
+                                         struct btrfs_block_group_cache *cache,
+                                         int is_dev_replace)
 {
        struct btrfs_mapping_tree *map_tree =
                &sctx->dev_root->fs_info->mapping_tree;
@@ -3445,8 +3447,18 @@ static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
        em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
        read_unlock(&map_tree->map_tree.lock);
 
-       if (!em)
-               return -EINVAL;
+       if (!em) {
+               /*
+                * Might have been an unused block group deleted by the cleaner
+                * kthread or relocation.
+                */
+               spin_lock(&cache->lock);
+               if (!cache->removed)
+                       ret = -EINVAL;
+               spin_unlock(&cache->lock);
+
+               return ret;
+       }
 
        map = (struct map_lookup *)em->bdev;
        if (em->start != chunk_offset)
@@ -3592,7 +3604,7 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
                dev_replace->cursor_left = found_key.offset;
                dev_replace->item_needs_writeback = 1;
                ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length,
-                                 found_key.offset, is_dev_replace);
+                                 found_key.offset, cache, is_dev_replace);
 
                /*
                 * flush, submit all pending read and write bios, afterwards