D5784: Add support for FreeBSD in FSUtils::getDirectoryFileSystem().

[Stefan Brüns]

bruns added a comment.
Restricted Application added a project: Baloo.


  The whole function as currently used is pointless.
  
  Currently, it sets the NO_COW flag on BTRFS, but this is insufficient:
  
  - XFS - https://lwn.net/Articles/747633/
  - F2FS
  - Hammer2 ?
  
  At least on Linux, the correct thing is to *try* to set the no_cow flag, and silently ignore any `EOPNOTSUPP` errors.
  
  Thats what I get on Linux for:
  
  - File without permission to write: `ioctl(3, FS_IOC_SETFLAGS, 0x7ffee879084c) = -1 EPERM (Operation not permitted)`
  - On an old XFS: `ioctl(3, FS_IOC_SETFLAGS, 0x7fff8e52467c) = -1 EOPNOTSUPP (Operation not supported)`
  - BTRFS: `ioctl(3, FS_IOC_SETFLAGS, 0x7fff06817a2c) = 0`
  
  This way the code is future proof even when a new FS appears or an old one gains new features.

REPOSITORY
  R293 Baloo

REVISION DETAIL
  https://phabricator.kde.org/D5784

To: tcberner, #freebsd, kfunk, poboiko
Cc: bruns, adridg, kfunk, #frameworks, ashaposhnikov, michaelh, astippich, spoorun, ngraham, alexeymin
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