Line data    Source code

       1             : // Copyright 2020 The LevelDB-Go and Pebble Authors. All rights reserved. Use
       2             : // of this source code is governed by a BSD-style license that can be found in
       3             : // the LICENSE file.
       4             : 
       5             : //go:build linux
       6             : // +build linux
       7             : 
       8             : package vfs
       9             : 
      10             : import "golang.org/x/sys/unix"
      11             : 
      12           1 : func (defaultFS) GetDiskUsage(path string) (DiskUsage, error) {
      13           1 :         stat := unix.Statfs_t{}
      14           1 :         if err := unix.Statfs(path, &stat); err != nil {
      15           0 :                 return DiskUsage{}, err
      16           0 :         }
      17             : 
      18             :         // We use stat.Frsize here rather than stat.Bsize because on
      19             :         // Linux Bavail and Bfree are in Frsize units.
      20             :         //
      21             :         // On most filesystems Frsize and Bsize will be set to the
      22             :         // same value, but on some filesystems bsize returns the
      23             :         // "optimal transfer block size"[1] which may be different
      24             :         // (typically larger) than the actual block size.
      25             :         //
      26             :         // This confusion is cleared up in the statvfs[2] libc function,
      27             :         // but the statfs system call used above varies across
      28             :         // platforms.
      29             :         //
      30             :         // Frsize is used by GNU coreutils and other libraries, so
      31             :         // this also helps ensure that we get the same results as one
      32             :         // would get if they ran `df` on the given path.
      33             :         //
      34             :         // [1] https://man7.org/linux/man-pages/man2/statfs.2.html
      35             :         // [2] https://man7.org/linux/man-pages/man3/statvfs.3.html
      36           1 :         freeBytes := uint64(stat.Frsize) * uint64(stat.Bfree)
      37           1 :         availBytes := uint64(stat.Frsize) * uint64(stat.Bavail)
      38           1 :         totalBytes := uint64(stat.Frsize) * uint64(stat.Blocks)
      39           1 :         return DiskUsage{
      40           1 :                 AvailBytes: availBytes,
      41           1 :                 TotalBytes: totalBytes,
      42           1 :                 UsedBytes:  totalBytes - freeBytes,
      43           1 :         }, nil
      44             : }