From 91ae02a63d25caccddd835fb201195fefe9d113b Mon Sep 17 00:00:00 2001
From: Ben Noordhuis <info@bnoordhuis.nl>
Date: Thu, 1 Jan 2026 22:33:44 +0100
Subject: [PATCH] unix,win: add f_frsize field to uv_statfs_t (#4984)

Fixes: https://github.com/libuv/libuv/issues/4983
---
 docs/src/fs.rst | 3 ++-
 include/uv.h    | 3 ++-
 src/unix/fs.c   | 5 +++++
 src/win/fs.c    | 1 +
 test/test-fs.c  | 1 +
 5 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/docs/src/fs.rst b/docs/src/fs.rst
index def767258..99524e702 100644
--- a/docs/src/fs.rst
+++ b/docs/src/fs.rst
@@ -129,7 +129,8 @@ Data types
             uint64_t f_bavail;
             uint64_t f_files;
             uint64_t f_ffree;
-            uint64_t f_spare[4];
+            uint64_t f_frsize;
+            uint64_t f_spare[3];
         } uv_statfs_t;
 
 .. c:enum:: uv_dirent_type_t
diff --git a/include/uv.h b/include/uv.h
index d1a77c749..41d7acc93 100644
--- a/include/uv.h
+++ b/include/uv.h
@@ -1262,7 +1262,8 @@ struct uv_statfs_s {
   uint64_t f_bavail;
   uint64_t f_files;
   uint64_t f_ffree;
-  uint64_t f_spare[4];
+  uint64_t f_frsize;
+  uint64_t f_spare[3];
 };
 
 typedef enum {
diff --git a/src/unix/fs.c b/src/unix/fs.c
index e66c9d299..fc0fe0a26 100644
--- a/src/unix/fs.c
+++ b/src/unix/fs.c
@@ -711,6 +711,11 @@ static int uv__fs_statfs(uv_fs_t* req) {
   stat_fs->f_bavail = buf.f_bavail;
   stat_fs->f_files = buf.f_files;
   stat_fs->f_ffree = buf.f_ffree;
+#if defined(__linux__)
+  stat_fs->f_frsize = buf.f_frsize;
+#else
+  stat_fs->f_frsize = buf.f_bsize;
+#endif
   req->ptr = stat_fs;
   return 0;
 }
diff --git a/src/win/fs.c b/src/win/fs.c
index 3bd610ba4..ca09ad46c 100644
--- a/src/win/fs.c
+++ b/src/win/fs.c
@@ -3154,6 +3154,7 @@ retry_get_full_path_name:
 
   stat_fs->f_type = 0;
   stat_fs->f_bsize = bytes_per_sector * sectors_per_cluster;
+  stat_fs->f_frsize = bytes_per_sector * sectors_per_cluster;
   stat_fs->f_blocks = total_clusters;
   stat_fs->f_bfree = free_clusters;
   stat_fs->f_bavail = free_clusters;
diff --git a/test/test-fs.c b/test/test-fs.c
index db4f6e841..44788dc26 100644
--- a/test/test-fs.c
+++ b/test/test-fs.c
@@ -363,6 +363,7 @@ static void statfs_cb(uv_fs_t* req) {
 #endif
 
   ASSERT_GT(stats->f_bsize, 0);
+  ASSERT_GT(stats->f_frsize, 0);
   ASSERT_GT(stats->f_blocks, 0);
   ASSERT_LE(stats->f_bfree, stats->f_blocks);
   ASSERT_LE(stats->f_bavail, stats->f_bfree);