Summary:
fs_posix.cc GetFreeSpace() calculates free space based upon a call to statvfs(). However, there are two extremely different values in statvfs's returned structure: f_bfree which is free space for root and f_bavail which is free space for non-root users. The existing code uses f_bfree. Many disks have 5 to 10% of the total disk space reserved for root only. Therefore GetFreeSpace() does not realize that non-root users may not have storage available.
This PR detects whether the effective posix user is root or not, then selects the appropriate available space value.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8370
Reviewed By: mrambacher
Differential Revision: D29032710
Pulled By: jay-zhuang
fbshipit-source-id: 57feba34ed035615a479956d28f98d85735281c0
5a2b4ed671