Merge branch 'for-linus-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/mason...

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

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 01bc36c..71261b4 100644 (file)
--- 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;
        }