1 files changed, 15 insertions, 62 deletions

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 69b59bf75882..c3c0c064c25d 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -6322,68 +6322,21 @@ 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;
-        }
+        /*
+         * We have found an extent item that changed without the inode item
+         * having changed. This can happen either after relocation (where the
+         * disk_bytenr of an extent item is replaced at
+         * relocation.c:replace_file_extents()) or after deduplication into a
+         * file in both the parent and send snapshots (where an extent item can
+         * get modified or replaced with a new one). Note that deduplication
+         * updates the inode item, but it only changes the iversion (sequence
+         * field in the inode item) of the inode, so if a file is deduplicated
+         * the same amount of times in both the parent and send snapshots, its
+         * iversion becames the same in both snapshots, whence the inode item is
+         * the same on both snapshots.
+         */
+        if (sctx->cur_ino != sctx->cmp_key->objectid)
+                return 0;
 
         if (!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted) {
                 if (result != BTRFS_COMPARE_TREE_DELETED)