Need copy_file_range() which uses FSCTL_DUPLICATE_EXTENTS_TO_FILE

[aureliencouderc]

MSYS2 file copy is EXTREMELY slow for big files on REFS on Windows 11.

Since Win10 is soon End-of-support MSYS2 more and more people use REFS, and there MSYS2 is slow.
It turns out that cmd.exe and powershell.exe cheat a bit when copying files on REFS: They do not copy data, they clone blocks via FSCTL_DUPLICATE_EXTENTS_TO_FILE.

coreutils cp and mv could do the same IF MSYS2 would implement copy_file_range() backed by FSCTL_DUPLICATE_EXTENTS_TO_FILE.

[ognevny]

just to clarify, is this exact for a code patched here, or it's a cygwin issue too? in the second case, you should send an email to cygwin devs

[aureliencouderc]

cygwin does not have a bug tracker. That is why I am posting it here.

[ognevny]

https://cygwin.com/problems.html

[sskras]

Also a https://cygwin.com/lists.html#available-lists quote:

• cygwin: This is the list for discussion of just about all things related to Cygwin. In general, you should send questions and bug reports here.

[jeremyd2019]

https://inbox.sourceware.org/cygwin/CALXu0Uee16dR-X812UpKNiE0CAVfBjQY_z1OBbyPdQgm_4zsZQ@mail.gmail.com/t/#u

[aureliencouderc]

https://inbox.sourceware.org/cygwin/CALXu0Uee16dR-X812UpKNiE0CAVfBjQY_z1OBbyPdQgm_4zsZQ@mail.gmail.com/t/#u

it looks that debate stalled at cygwin level, while powershell now has a performance advantage

[jeremyd2019]

no "debate", just waiting for the next step when somebody sends a patch rather than expecting somebody else to do it. SHTDI, PTC

[eabase]

@ognevny

https://cygwin.com/problems.html

Unbelievable that Cygwin still insist on using that ancient and 100% user unfriendly + 💩 UX, email list to report and track bugs. No wonder everything is moving so slow there...

[lazka]

@eabase Please provide feedback respectfully without dismissive language.

[eabase]

@lazka
My apologies, I will behave. Thx for feedback.