perf trace: Support using -f to override perf.data file ownership

Enable perf trace to use perf.data when it is not owned by current user
or root.

Example:

# perf trace record ls
# chown Yunlong.Song:Yunlong.Song perf.data
# ls -al perf.data
-rw------- 1 Yunlong.Song Yunlong.Song 4153101 Apr 2 15:28 perf.data
# id
uid=0(root) gid=0(root) groups=0(root),64(pkcs11)

Before this patch:

# perf trace -i perf.data
File perf.data not owned by current user or root (use -f to override)
# perf trace -i perf.data -f
Error: unknown switch `f'

usage: perf trace [<options>] [<command>]
or: perf trace [<options>] -- <command> [<options>]
or: perf trace record [<options>] [<command>]
or: perf trace record [<options>] -- <command> [<options>]

--event <event> event selector. use 'perf list' to list
available events
--comm show the thread COMM next to its id
--tool_stats show tool stats
-e, --expr <expr> list of events to trace
-o, --output <file> output file name
-i, --input <file> Analyze events in file
-p, --pid <pid> trace events on existing process id
-t, --tid <tid> trace events on existing thread id
--filter-pids <float>
...

As shown above, the -f option does not work at all.

After this patch:

# perf trace -i perf.data
File perf.data not owned by current user or root (use -f to override)
# perf trace -i perf.data -f
0.056 ( 0.002 ms): ls/47325 brk( ...
0.108 ( 0.018 ms): ls/47325 mmap(len: 4096, prot: READ|WRITE, ...
0.145 ( 0.013 ms): ls/47325 access(filename: 0x7f31259a0eb0, ...
0.172 ( 0.008 ms): ls/47325 open(filename: 0x7fffeb9a0d00, ...
0.180 ( 0.004 ms): ls/47325 stat(filename: 0x7fffeb9a0d00, ...
0.185 ( 0.004 ms): ls/47325 open(filename: 0x7fffeb9a0d00, ...
0.189 ( 0.003 ms): ls/47325 stat(filename: 0x7fffeb9a0d00, ...
0.195 ( 0.004 ms): ls/47325 open(filename: 0x7fffeb9a0d00, ...
0.199 ( 0.002 ms): ls/47325 stat(filename: 0x7fffeb9a0d00, ...
0.205 ( 0.004 ms): ls/47325 open(filename: 0x7fffeb9a0d00, ...
0.211 ( 0.004 ms): ls/47325 stat(filename: 0x7fffeb9a0d00, ...
0.220 ( 0.007 ms): ls/47325 open(filename: 0x7f312599e8ff, ...
...
...

As shown above, the -f option really works now.

Signed-off-by: Yunlong Song <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-trace.c

···
 	bool			show_comm;
 	bool			show_tool_stats;
 	bool			trace_syscalls;
+	bool			force;
 	int			trace_pgfaults;
 };
 
···
 	struct perf_data_file file = {
 		.path  = input_name,
 		.mode  = PERF_DATA_MODE_READ,
+		.force = trace->force,
 	};
 	struct perf_session *session;
 	struct perf_evsel *evsel;
···
 	OPT_CALLBACK_DEFAULT('F', "pf", &trace.trace_pgfaults, "all|maj|min",
 		     "Trace pagefaults", parse_pagefaults, "maj"),
 	OPT_BOOLEAN(0, "syscalls", &trace.trace_syscalls, "Trace syscalls"),
+	OPT_BOOLEAN('f', "force", &trace.force, "don't complain, do it"),
 	OPT_END()
 	};
 	const char * const trace_subcommands[] = { "record", NULL };