Hi,
On 2024/4/3 15:22, Sweet Tea Dorminy wrote:
For many years, various btrfs users have written programs to discover
the actual disk space used by files, using root-only interfaces.
However, this information is a great fit for fiemap: it is inherently
tied to extent information, all filesystems can use it, and the
capabilities required for FIEMAP make sense for this additional
information also.
Hence, this patchset adds various additional information to fiemap,
and extends filesystems (but not iomap) to return it. This uses some of
the reserved padding in the fiemap extent structure, so programs unaware
of the changes will be unaffected.
I'm not sure why here iomap was excluded technically or I'm missing some
previous comments?
This is based on next-20240403. I've tested the btrfs part of this with
the standard btrfs testing matrix locally and manually, and done minimal
testing of the non-btrfs parts.
I'm unsure whether btrfs should be returning the entire physical extent
referenced by a particular logical range, or just the part of the
physical extent referenced by that range. The v2 thread has a discussion
of this.
Could you also make iomap support new FIEMAP physical extent information?
since compressed EROFS uses iomap FIEMAP interface to report compressed
extents ("z_erofs_iomap_report_ops") but there is no way to return
correct compressed lengths, that is unexpected.
Thanks,
Gao Xiang
