Btrfs: fix page reading in extent_same ioctl leading to csum errors

[firefly-linux-kernel-4.4.55.git] / fs / btrfs / scrub.c

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 6b3fd51d9a99ce95167fee40e79d577b992d5682..b091d94ceef68013e992161b0aaf31b47cc645dc 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
@@ -3629,6 +3641,28 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
                if (ro_set)
                        btrfs_dec_block_group_ro(root, cache);
 
+               /*
+                * We might have prevented the cleaner kthread from deleting
+                * this block group if it was already unused because we raced
+                * and set it to RO mode first. So add it back to the unused
+                * list, otherwise it might not ever be deleted unless a manual
+                * balance is triggered or it becomes used and unused again.
+                */
+               spin_lock(&cache->lock);
+               if (!cache->removed && !cache->ro && cache->reserved == 0 &&
+                   btrfs_block_group_used(&cache->item) == 0) {
+                       spin_unlock(&cache->lock);
+                       spin_lock(&fs_info->unused_bgs_lock);
+                       if (list_empty(&cache->bg_list)) {
+                               btrfs_get_block_group(cache);
+                               list_add_tail(&cache->bg_list,
+                                             &fs_info->unused_bgs);
+                       }
+                       spin_unlock(&fs_info->unused_bgs_lock);
+               } else {
+                       spin_unlock(&cache->lock);
+               }
+
                btrfs_put_block_group(cache);
                if (ret)
                        break;