syscall, x/sys/unix: wrong order of arguments for SyncFileRange on linux/ppc64{,le}

[tklauser]

While investigating what was wrong with https://golang.org/cl/133015 (see #27475), I noticed that the order of the syscall arguments in the SyncFileRange implementation is wrong for ppc64 and ppc64le. They use the SYS_SYNC_FILE_RANGE2 syscall which is defined as:

https://github.com/torvalds/linux/blob/60c1f89241d49bacf71035470684a8d7b4bb46ea/fs/sync.c#L371-L375

while SYS_SYNC_FILE_RANGE used by all other GOARCHes is defined as:

https://github.com/torvalds/linux/blob/60c1f89241d49bacf71035470684a8d7b4bb46ea/fs/sync.c#L363-L367

Note the different position of the flags argument. This should be fixed by using appropriate wrappers on linux/ppc64{,le}.

/cc @bradfitz @ianlancetaylor

[tklauser]

Also see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=edd5cd4a9424f22b0fa08bef5e299d41befd5622 for the reasoning for there being two syscalls.

[tklauser]

The implementation on linux/arm64 is correct, SYS_SYNC_FILE_RANGE and SYS_SYNC_FILE_RANGE2 have the same value and call the sync_file_range syscall.

[gopherbot]

Change https://golang.org/cl/133195 mentions this issue: syscall: correct argument order for SyncFileRange syscall on linux/ppc64{,le

[gopherbot]

Change https://golang.org/cl/133215 mentions this issue: unix: correct argument order for SyncFileRange syscall on linux/ppc64{,le}