fs: expose frsize field in statfs

Expose `f_frsize` from libuv's `uv_statfs_t` as `statfs.frsize`.
Per POSIX, `f_blocks`, `f_bfree`, and `f_bavail` are expressed in
units of `f_frsize`, not `f_bsize`. On most filesystems the two
values are typically equal, but some filesystem drivers report a
different `f_bsize`, making it impossible to compute accurate disk
usage without `frsize`.
Refs: libuv/libuv#4983
PR-URL: #62277
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Gürgün Dayıoğlu <hey@gurgun.day>

Author: verycosy

doc/api/fs.md

@@ -7556,6 +7556,7 @@ numeric values will be `bigint` instead of `number`.
 StatFs {
  type:1397114950,
  bsize:4096,
+ frsize:4096,
  blocks:121938943,
  bfree:61058895,
  bavail:61058895,
@@ -7570,6 +7571,7 @@ StatFs {
 StatFs {
  type:1397114950n,
  bsize:4096n,
+ frsize:4096n,
  blocks:121938943n,
  bfree:61058895n,
  bavail:61058895n,
@@ -7626,6 +7628,16 @@ added:
 
 Optimal transfer block size.
 
+#### `statfs.frsize`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* Type: {number|bigint}
+
+Fundamental file system block size.
+
 #### `statfs.ffree`
 
 <!-- YAML

lib/internal/fs/utils.js

@@ -575,9 +575,10 @@ function getStatsFromBinding(stats, offset = 0) {
 }
 
 classStatFs{
-constructor(type,bsize,blocks,bfree,bavail,files,ffree){
+constructor(type,bsize,frsize,blocks,bfree,bavail,files,ffree){
 this.type=type;
 this.bsize=bsize;
+this.frsize=frsize;
 this.blocks=blocks;
 this.bfree=bfree;
 this.bavail=bavail;
@@ -588,7 +589,7 @@ class StatFs {
 
 functiongetStatFsFromBinding(stats){
 returnnewStatFs(
-stats[0],stats[1],stats[2],stats[3],stats[4],stats[5],stats[6],
+stats[0],stats[1],stats[2],stats[3],stats[4],stats[5],stats[6],stats[7],
 );
 }
 

src/node_file-inl.h

@@ -153,6 +153,7 @@ void FillStatFsArray(AliasedBufferBase<NativeT, V8T>* fields,
 
 SET_FIELD(kType, s->f_type);
 SET_FIELD(kBSize, s->f_bsize);
+SET_FIELD(kFrSize, s->f_frsize);
 SET_FIELD(kBlocks, s->f_blocks);
 SET_FIELD(kBFree, s->f_bfree);
 SET_FIELD(kBAvail, s->f_bavail);

src/node_file.h

@@ -44,6 +44,7 @@ constexpr size_t kFsStatsBufferLength =
 enumclassFsStatFsOffset {
 kType = 0,
 kBSize,
+kFrSize,
 kBlocks,
 kBFree,
 kBAvail,

test/parallel/test-fs-promises.js

@@ -89,6 +89,7 @@ function verifyStatFsObject(stat, isBigint = false) {
 assert.strictEqual(typeofstat,'object');
 assert.strictEqual(typeofstat.type,valueType);
 assert.strictEqual(typeofstat.bsize,valueType);
+assert.strictEqual(typeofstat.frsize,valueType);
 assert.strictEqual(typeofstat.blocks,valueType);
 assert.strictEqual(typeofstat.bfree,valueType);
 assert.strictEqual(typeofstat.bavail,valueType);

test/parallel/test-fs-statfs.js

@@ -7,7 +7,7 @@ function verifyStatFsObject(statfs, isBigint = false) {
 constvalueType=isBigint ? 'bigint' : 'number';
 
 [
-'type','bsize','blocks','bfree','bavail','files','ffree',
+'type','bsize','frsize','blocks','bfree','bavail','files','ffree',
 ].forEach((k)=>{
 assert.ok(Object.hasOwn(statfs,k));
 assert.strictEqual(typeofstatfs[k],valueType,