lockfile: merge Seek+Read/Write into Pread/Pwrite

[giuseppe]

drop a call to Seek and use the Pread and Pwrite syscalls instead that
already accept an offset.

Signed-off-by: Giuseppe Scrivano [email protected]

[saschagrunert]

LGTM

[rhatdan]

Nice
LGTM

[rhatdan]

@giuseppe How did you find this?

[giuseppe]

@giuseppe How did you find this?

I was looking at strace and noticed way too many lseek calls:

# strace -q -f -c -e lseek podman run --rm fedora true
[pid 2842325] ????( <detached ...>
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
100.00    0.000471           3       120           lseek
------ ----------- ----------- --------- --------- ----------------
100.00    0.000471           3       120           total

with the fix:

# strace -q -f -c -e lseek bin/podman run --rm fedora true
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
100.00    0.000073           2        28           lseek
------ ----------- ----------- --------- --------- ----------------
100.00    0.000073           2        28           total

[vrothberg]

I adore such improvements. Great catch!