From d041e1e4c64f61664266fc10758cd9c5366fa6fa Mon Sep 17 00:00:00 2001
From: Adam Lesinski <adam@runloop.ai>
Date: Mon, 24 Aug 2026 16:21:20 -0700
Subject: [PATCH] fix(mkfs): reserve correct htree checksum tail

---
 .github/workflows/cmake.yml                      |  9 ++++++++-
 CMake/Finde2fs.cmake                             |  2 ++
 .../patches/e2fsprogs-fix-htree-root-limit.patch | 16 ++++++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 CMake/patches/e2fsprogs-fix-htree-root-limit.patch

diff --git a/.github/workflows/cmake.yml b/.github/workflows/cmake.yml
index d473ca7e..45cf75ef 100644
--- a/.github/workflows/cmake.yml
+++ b/.github/workflows/cmake.yml
@@ -87,6 +87,13 @@ jobs:
         ls obd_mp
         sudo diff -r --exclude "lost+found" test_data obd_mp
         sudo umount obd_mp
+        mkdir -p htree_data/crowded
+        for i in $(seq 1 1000); do touch "htree_data/crowded/file-${i}"; done
+        tar -cf htree.tar -C htree_data .
+        truncate -s 1g htree.img
+        /opt/overlaybd/bin/overlaybd-apply --mkfs --raw htree.tar htree.img
+        sudo e2fsck -fn htree.img 2>&1 | tee htree-e2fsck.log || true
+        ! grep -F "invalid limit (506)" htree-e2fsck.log
     - name: E2E Test turboOCIv1
       working-directory: ${{github.workspace}}/build
       shell: bash
@@ -124,4 +131,4 @@ jobs:
       uses: namespacelabs/breakpoint-action@v0
       with:
         duration: 30m
-        authorized-users: dines-rl
\ No newline at end of file
+        authorized-users: dines-rl
diff --git a/CMake/Finde2fs.cmake b/CMake/Finde2fs.cmake
index 15c58fda..a89cf8ba 100644
--- a/CMake/Finde2fs.cmake
+++ b/CMake/Finde2fs.cmake
@@ -1,10 +1,12 @@
 if(NOT ORIGIN_EXT2FS)
     message("Add and build standalone libext2fs")
     include(FetchContent)
+    set(_e2fsprogs_htree_patch "${CMAKE_CURRENT_LIST_DIR}/patches/e2fsprogs-fix-htree-root-limit.patch")
     FetchContent_Declare(
         e2fsprogs
         GIT_REPOSITORY https://github.com/data-accelerator/e2fsprogs.git
         GIT_TAG b4cf6c751196a12b1df9a269d8e0b516b99fe6a7
+        PATCH_COMMAND sh -c "git apply --reverse --check '${_e2fsprogs_htree_patch}' 2>/dev/null || git apply '${_e2fsprogs_htree_patch}'"
     )
     FetchContent_GetProperties(e2fsprogs)
 
diff --git a/CMake/patches/e2fsprogs-fix-htree-root-limit.patch b/CMake/patches/e2fsprogs-fix-htree-root-limit.patch
new file mode 100644
index 00000000..414ae855
--- /dev/null
+++ b/CMake/patches/e2fsprogs-fix-htree-root-limit.patch
@@ -0,0 +1,16 @@
+diff --git a/lib/ext2fs/expanddir.c b/lib/ext2fs/expanddir.c
+index 898a362c..d86d695e 100644
+--- a/lib/ext2fs/expanddir.c
++++ b/lib/ext2fs/expanddir.c
+@@ -185,7 +185,10 @@ static errcode_t make_indexed_dir(ext2_filsys fs, ext2_ino_t dir, struct ext2_i
+     entries = root->entries;
+     entries->block = ext2fs_cpu_to_le32(1);
+     ((struct ext2_dx_countlimit *) entries)->count = ext2fs_cpu_to_le16(1);
+-    ((struct ext2_dx_countlimit *) entries)->limit = ext2fs_cpu_to_le16((blocksize - (32 + csum_size)) / sizeof(struct ext2_dx_entry));
++    ((struct ext2_dx_countlimit *) entries)->limit = ext2fs_cpu_to_le16(
++        (blocksize - 32 -
++         (csum_size ? sizeof(struct ext2_dx_tail) : 0)) /
++        sizeof(struct ext2_dx_entry));
+ 
+     /* write out blocks */
+     for (int i = 0; i < dx_info.levels; i++)