tools lib api fs: Add bpf_fs filesystem detector

Allow mounting of the BPF filesystem at /sys/fs/bpf.
Signed-off-by: Joe Stringer <joe@ovn.org>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/20170126212001.14103-6-joe@ovn.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/api/fs/fs.c

@@ -38,6 +38,10 @@
 #define HUGETLBFS_MAGIC        0x958458f6
 #endif
 
+#ifndef BPF_FS_MAGIC
+#define BPF_FS_MAGIC           0xcafe4a11
+#endif
+
 static const char * const sysfs__fs_known_mountpoints[] = {
 	"/sys",
 	0,
@@ -75,6 +79,11 @@ static const char * const hugetlbfs__known_mountpoints[] = {
 	0,
 };
 
+static const char * const bpf_fs__known_mountpoints[] = {
+	"/sys/fs/bpf",
+	0,
+};
+
 struct fs {
 	const char		*name;
 	const char * const	*mounts;
@@ -89,6 +98,7 @@ enum {
 	FS__DEBUGFS = 2,
 	FS__TRACEFS = 3,
 	FS__HUGETLBFS = 4,
+	FS__BPF_FS = 5,
 };
 
 #ifndef TRACEFS_MAGIC
@@ -121,6 +131,11 @@ static struct fs fs__entries[] = {
 		.mounts = hugetlbfs__known_mountpoints,
 		.magic	= HUGETLBFS_MAGIC,
 	},
+	[FS__BPF_FS] = {
+		.name	= "bpf",
+		.mounts = bpf_fs__known_mountpoints,
+		.magic	= BPF_FS_MAGIC,
+	},
 };
 
 static bool fs__read_mounts(struct fs *fs)
@@ -280,6 +295,7 @@ FS(procfs,  FS__PROCFS);
 FS(debugfs, FS__DEBUGFS);
 FS(tracefs, FS__TRACEFS);
 FS(hugetlbfs, FS__HUGETLBFS);
+FS(bpf_fs, FS__BPF_FS);
 
 int filename__read_int(const char *filename, int *value)
 {

tools/lib/api/fs/fs.h

@@ -22,6 +22,7 @@ FS(procfs)
 FS(debugfs)
 FS(tracefs)
 FS(hugetlbfs)
+FS(bpf_fs)
 
 #undef FS