[PATCH bpf-next] bpftool: Support bpffs mountpoint as pin path for prog loadall

[Pengcheng Yang <yangpc@xxxxxxxxxx>]

Currently, when using prog loadall, if the pin path is a bpffs
mountpoint, bpffs will be repeatedly mounted to the parent directory
of the bpffs mountpoint path.

For example,
    $ bpftool prog loadall test.o /sys/fs/bpf
currently bpffs will be repeatedly mounted to /sys/fs.

Signed-off-by: Pengcheng Yang <yangpc@xxxxxxxxxx>
---
 tools/bpf/bpftool/common.c | 9 ++++++---
 tools/bpf/bpftool/iter.c   | 2 +-
 tools/bpf/bpftool/main.h   | 2 +-
 tools/bpf/bpftool/prog.c   | 2 +-
 4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index 5a73ccf14332..880fcb45f89f 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -68,7 +68,7 @@ void p_info(const char *fmt, ...)
 	va_end(ap);
 }
 
-static bool is_bpffs(char *path)
+static bool is_bpffs(const char *path)
 {
 	struct statfs st_fs;
 
@@ -244,13 +244,16 @@ int open_obj_pinned_any(const char *path, enum bpf_obj_type exp_type)
 	return fd;
 }
 
-int mount_bpffs_for_pin(const char *name)
+int mount_bpffs_for_pin(const char *name, bool is_dir)
 {
 	char err_str[ERR_MAX_LEN];
 	char *file;
 	char *dir;
 	int err = 0;
 
+	if (is_dir && is_bpffs(name))
+		return err;
+
 	file = malloc(strlen(name) + 1);
 	if (!file) {
 		p_err("mem alloc failed");
@@ -286,7 +289,7 @@ int do_pin_fd(int fd, const char *name)
 {
 	int err;
 
-	err = mount_bpffs_for_pin(name);
+	err = mount_bpffs_for_pin(name, false);
 	if (err)
 		return err;
 
diff --git a/tools/bpf/bpftool/iter.c b/tools/bpf/bpftool/iter.c
index 9a1d2365a297..6b0e5202ca7a 100644
--- a/tools/bpf/bpftool/iter.c
+++ b/tools/bpf/bpftool/iter.c
@@ -76,7 +76,7 @@ static int do_pin(int argc, char **argv)
 		goto close_obj;
 	}
 
-	err = mount_bpffs_for_pin(path);
+	err = mount_bpffs_for_pin(path, false);
 	if (err)
 		goto close_link;
 
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 0ef373cef4c7..665f23f68066 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -142,7 +142,7 @@ const char *get_fd_type_name(enum bpf_obj_type type);
 char *get_fdinfo(int fd, const char *key);
 int open_obj_pinned(const char *path, bool quiet);
 int open_obj_pinned_any(const char *path, enum bpf_obj_type exp_type);
-int mount_bpffs_for_pin(const char *name);
+int mount_bpffs_for_pin(const char *name, bool is_dir);
 int do_pin_any(int argc, char **argv, int (*get_fd_by_id)(int *, char ***));
 int do_pin_fd(int fd, const char *name);
 
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index afbe3ec342c8..473ec01c00d6 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -1747,7 +1747,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 		goto err_close_obj;
 	}
 
-	err = mount_bpffs_for_pin(pinfile);
+	err = mount_bpffs_for_pin(pinfile, !first_prog_only);
 	if (err)
 		goto err_close_obj;
 
-- 
2.38.1