Btrfs: Fix allocation completions in tree log replay

After a crash, the tree log code uses btrfs_alloc_logged_extent to
record allocations of data extents that it finds in the log tree.  These
come in basically random order, which does not fit how
btrfs_remove_free_space() expects to be called.

btrfs_remove_free_space was changed to support recording an extent
allocation in the middle of a region of free space.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 01c26e8ae555..f1d9b6bc23ba 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -306,11 +306,45 @@ int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
 
                 ret = link_free_space(block_group, info);
                 BUG_ON(ret);
+        } else if (info && info->offset < offset &&
+                   info->offset + info->bytes >= offset + bytes) {
+                u64 old_start = info->offset;
+                /*
+                 * we're freeing space in the middle of the info,
+                 * this can happen during tree log replay
+                 *
+                 * first unlink the old info and then
+                 * insert it again after the hole we're creating
+                 */
+                unlink_free_space(block_group, info);
+                if (offset + bytes < info->offset + info->bytes) {
+                        u64 old_end = info->offset + info->bytes;
+
+                        info->offset = offset + bytes;
+                        info->bytes = old_end - info->offset;
+                        ret = link_free_space(block_group, info);
+                        BUG_ON(ret);
+                } else {
+                        /* the hole we're creating ends at the end
+                         * of the info struct, just free the info
+                         */
+                        kfree(info);
+                }
+
+                /* step two, insert a new info struct to cover anything
+                 * before the hole
+                 */
+                spin_unlock(&block_group->lock);
+                ret = btrfs_add_free_space(block_group, old_start,
+                                           offset - old_start);
+                BUG_ON(ret);
+                goto out_nolock;
         } else {
                 WARN_ON(1);
         }
 out:
         spin_unlock(&block_group->lock);
+out_nolock:
         return ret;
 }