linux-kernel - [PATCH 17/17] file: Rename __close_fd to close

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Message-Id: <20200817220425.9389-17-ebiederm@xmission.com>
Date:   Mon, 17 Aug 2020 17:04:25 -0500
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-fsdevel@...r.kernel.org, criu@...nvz.org,
        bpf@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Oleg Nesterov <oleg@...hat.com>,
        Cyrill Gorcunov <gorcunov@...il.com>,
        Jann Horn <jann@...jh.net>, Kees Cook <keescook@...omium.org>,
        Daniel P. Berrangé <berrange@...hat.com>,
        Jeff Layton <jlayton@...hat.com>,
        Miklos Szeredi <miklos@...redi.hu>,
        Matthew Wilcox <willy@...ian.org>,
        "J. Bruce Fields" <bfields@...ldses.org>,
        Matthew Wilcox <matthew@....cx>,
        Trond Myklebust <trond.myklebust@....uio.no>,
        Chris Wright <chrisw@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH 17/17] file: Rename __close_fd to close_fd and remove the files parameter

The function __close_fd was added to support binder[1].  Now that
binder has been fixed to no longer need __close_fd[2] and
get_files_struct has been removed it is no longer possible to
correctly call __close_fd with anything current->files pass as it's
files parameter.

Therefore transform the files parameter into a local variable
initialized to current->files, and rename __close_fd to close_fd to
reflect this change, and keep it in sync with the similar changes to
__alloc_fd, and __fd_install.

This removes the need for callers to care about the extra care that
needs to be take if anything except current->files is passed, by
limiting the callers to only operation on current->files.

[1] 483ce1d4b8c3 ("take descriptor-related part of close() to file.c")
[2] 44d8047f1d87 ("binder: use standard functions to allocate fds")
Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 fs/file.c                | 10 ++++------
 fs/open.c                |  2 +-
 include/linux/fdtable.h  |  3 +--
 include/linux/syscalls.h |  6 +++---
 4 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/fs/file.c b/fs/file.c
index 221fc4f97f61..b06b04d65070 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -614,11 +614,9 @@ static struct file *pick_file(struct files_struct *files, unsigned fd)
 	return file;
 }
 
-/*
- * The same warnings as for __alloc_fd()/__fd_install() apply here...
- */
-int __close_fd(struct files_struct *files, unsigned fd)
+int close_fd(unsigned fd)
 {
+	struct files_struct *files = current->files;
 	struct file *file;
 
 	file = pick_file(files, fd);
@@ -627,7 +625,7 @@ int __close_fd(struct files_struct *files, unsigned fd)
 
 	return filp_close(file, files);
 }
-EXPORT_SYMBOL(__close_fd); /* for ksys_close() */
+EXPORT_SYMBOL(close_fd); /* for ksys_close() */
 
 /**
  * __close_range() - Close all file descriptors in a given range.
@@ -1010,7 +1008,7 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags)
 	struct files_struct *files = current->files;
 
 	if (!file)
-		return __close_fd(files, fd);
+		return close_fd(fd);
 
 	if (fd >= rlimit(RLIMIT_NOFILE))
 		return -EBADF;
diff --git a/fs/open.c b/fs/open.c
index 9af548fb841b..581a674d7eee 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1292,7 +1292,7 @@ EXPORT_SYMBOL(filp_close);
  */
 SYSCALL_DEFINE1(close, unsigned int, fd)
 {
-	int retval = __close_fd(current->files, fd);
+	int retval = close_fd(fd);
 
 	/* can't restart close syscall because file table entry was cleared */
 	if (unlikely(retval == -ERESTARTSYS ||
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index d8f6c4921d85..d1b8f3d85493 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -116,8 +116,7 @@ int iterate_fd(struct files_struct *, unsigned,
 		int (*)(const void *, struct file *, unsigned),
 		const void *);
 
-extern int __close_fd(struct files_struct *files,
-		      unsigned int fd);
+extern int close_fd(unsigned int fd);
 extern int __close_range(unsigned int fd, unsigned int max_fd, unsigned int flags);
 extern int __close_fd_get_file(unsigned int fd, struct file **res);
 extern int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 75ac7f8ae93c..a3f48cf49206 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1293,16 +1293,16 @@ static inline long ksys_ftruncate(unsigned int fd, loff_t length)
 	return do_sys_ftruncate(fd, length, 1);
 }
 
-extern int __close_fd(struct files_struct *files, unsigned int fd);
+extern int close_fd(unsigned int fd);
 
 /*
  * In contrast to sys_close(), this stub does not check whether the syscall
  * should or should not be restarted, but returns the raw error codes from
- * __close_fd().
+ * close_fd().
  */
 static inline int ksys_close(unsigned int fd)
 {
-	return __close_fd(current->files, fd);
+	return close_fd(fd);
 }
 
 extern long do_sys_truncate(const char __user *pathname, loff_t length);
-- 
2.25.0