[PATCH 04/12] bpf: use __anon_inode_getfd

[Christoph Hellwig <hch@lst.de>]

Use __anon_inode_getfd instead of opencoding the logic using
get_unused_fd_flags + anon_inode_getfile.  Also switch the
bpf_link_new_file calling conventions to match __anon_inode_getfd.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/bpf.h  |  2 +-
 kernel/bpf/cgroup.c  |  6 +++---
 kernel/bpf/syscall.c | 31 +++++++++----------------------
 3 files changed, 13 insertions(+), 26 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index fd2b2322412d7..539649fe8b885 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1103,7 +1103,7 @@ void bpf_link_cleanup(struct bpf_link *link, struct file *link_file,
 void bpf_link_inc(struct bpf_link *link);
 void bpf_link_put(struct bpf_link *link);
 int bpf_link_new_fd(struct bpf_link *link);
-struct file *bpf_link_new_file(struct bpf_link *link, int *reserved_fd);
+int bpf_link_new_file(struct bpf_link *link, struct file **link_file);
 struct bpf_link *bpf_link_get_from_fd(u32 ufd);
 
 int bpf_obj_pin_user(u32 ufd, const char __user *pathname);
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index cb305e71e7deb..8605287adcd9e 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -836,10 +836,10 @@ int cgroup_bpf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
 	link->cgroup = cgrp;
 	link->type = attr->link_create.attach_type;
 
-	link_file = bpf_link_new_file(&link->link, &link_fd);
-	if (IS_ERR(link_file)) {
+	link_fd = bpf_link_new_file(&link->link, &link_file);
+	if (link_fd < 0) {
 		kfree(link);
-		err = PTR_ERR(link_file);
+		err = link_fd;
 		goto out_put_cgroup;
 	}
 
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 64783da342020..cb2364e17423c 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2307,23 +2307,10 @@ int bpf_link_new_fd(struct bpf_link *link)
  * complicated and expensive operations and should be delayed until all the fd
  * reservation and anon_inode creation succeeds.
  */
-struct file *bpf_link_new_file(struct bpf_link *link, int *reserved_fd)
+int bpf_link_new_file(struct bpf_link *link, struct file **file)
 {
-	struct file *file;
-	int fd;
-
-	fd = get_unused_fd_flags(O_CLOEXEC);
-	if (fd < 0)
-		return ERR_PTR(fd);
-
-	file = anon_inode_getfile("bpf_link", &bpf_link_fops, link, O_CLOEXEC);
-	if (IS_ERR(file)) {
-		put_unused_fd(fd);
-		return file;
-	}
-
-	*reserved_fd = fd;
-	return file;
+	return __anon_inode_getfd("bpf_link", &bpf_link_fops, link, O_CLOEXEC,
+			file);
 }
 
 struct bpf_link *bpf_link_get_from_fd(u32 ufd)
@@ -2406,10 +2393,10 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog)
 	}
 	bpf_link_init(&link->link, &bpf_tracing_link_lops, prog);
 
-	link_file = bpf_link_new_file(&link->link, &link_fd);
-	if (IS_ERR(link_file)) {
+	link_fd = bpf_link_new_file(&link->link, &link_file);
+	if (link_fd < 0) {
 		kfree(link);
-		err = PTR_ERR(link_file);
+		err = link_fd;
 		goto out_put_prog;
 	}
 
@@ -2520,10 +2507,10 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
 	bpf_link_init(&link->link, &bpf_raw_tp_lops, prog);
 	link->btp = btp;
 
-	link_file = bpf_link_new_file(&link->link, &link_fd);
-	if (IS_ERR(link_file)) {
+	link_fd = bpf_link_new_file(&link->link, &link_file);
+	if (link_fd < 0) {
 		kfree(link);
-		err = PTR_ERR(link_file);
+		err = link_fd;
 		goto out_put_btp;
 	}
 
-- 
2.26.2