1 files changed, 58 insertions, 0 deletions

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 01bc36cec26e..71261b459863 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -5805,6 +5805,64 @@ static int changed_extent(struct send_ctx *sctx,
         int ret = 0;
 
         if (sctx->cur_ino != sctx->cmp_key->objectid) {
+
+                if (result == BTRFS_COMPARE_TREE_CHANGED) {
+                        struct extent_buffer *leaf_l;
+                        struct extent_buffer *leaf_r;
+                        struct btrfs_file_extent_item *ei_l;
+                        struct btrfs_file_extent_item *ei_r;
+
+                        leaf_l = sctx->left_path->nodes[0];
+                        leaf_r = sctx->right_path->nodes[0];
+                        ei_l = btrfs_item_ptr(leaf_l,
+                                              sctx->left_path->slots[0],
+                                              struct btrfs_file_extent_item);
+                        ei_r = btrfs_item_ptr(leaf_r,
+                                              sctx->right_path->slots[0],
+                                              struct btrfs_file_extent_item);
+
+                        /*
+                         * We may have found an extent item that has changed
+                         * only its disk_bytenr field and the corresponding
+                         * inode item was not updated. This case happens due to
+                         * very specific timings during relocation when a leaf
+                         * that contains file extent items is COWed while
+                         * relocation is ongoing and its in the stage where it
+                         * updates data pointers. So when this happens we can
+                         * safely ignore it since we know it's the same extent,
+                         * but just at different logical and physical locations
+                         * (when an extent is fully replaced with a new one, we
+                         * know the generation number must have changed too,
+                         * since snapshot creation implies committing the current
+                         * transaction, and the inode item must have been updated
+                         * as well).
+                         * This replacement of the disk_bytenr happens at
+                         * relocation.c:replace_file_extents() through
+                         * relocation.c:btrfs_reloc_cow_block().
+                         */
+                        if (btrfs_file_extent_generation(leaf_l, ei_l) ==
+                            btrfs_file_extent_generation(leaf_r, ei_r) &&
+                            btrfs_file_extent_ram_bytes(leaf_l, ei_l) ==
+                            btrfs_file_extent_ram_bytes(leaf_r, ei_r) &&
+                            btrfs_file_extent_compression(leaf_l, ei_l) ==
+                            btrfs_file_extent_compression(leaf_r, ei_r) &&
+                            btrfs_file_extent_encryption(leaf_l, ei_l) ==
+                            btrfs_file_extent_encryption(leaf_r, ei_r) &&
+                            btrfs_file_extent_other_encoding(leaf_l, ei_l) ==
+                            btrfs_file_extent_other_encoding(leaf_r, ei_r) &&
+                            btrfs_file_extent_type(leaf_l, ei_l) ==
+                            btrfs_file_extent_type(leaf_r, ei_r) &&
+                            btrfs_file_extent_disk_bytenr(leaf_l, ei_l) !=
+                            btrfs_file_extent_disk_bytenr(leaf_r, ei_r) &&
+                            btrfs_file_extent_disk_num_bytes(leaf_l, ei_l) ==
+                            btrfs_file_extent_disk_num_bytes(leaf_r, ei_r) &&
+                            btrfs_file_extent_offset(leaf_l, ei_l) ==
+                            btrfs_file_extent_offset(leaf_r, ei_r) &&
+                            btrfs_file_extent_num_bytes(leaf_l, ei_l) ==
+                            btrfs_file_extent_num_bytes(leaf_r, ei_r))
+                                return 0;
+                }
+
                 inconsistent_snapshot_error(sctx, result, "extent");
                 return -EIO;
         }