From: "Eric W. Biederman" <ebiederm@xmission.com>
To: linux-kernel@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, criu@openvz.org,
bpf@vger.kernel.org,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Alexander Viro" <viro@zeniv.linux.org.uk>,
"Christian Brauner" <christian.brauner@ubuntu.com>,
"Oleg Nesterov" <oleg@redhat.com>,
"Cyrill Gorcunov" <gorcunov@gmail.com>,
"Jann Horn" <jann@thejh.net>, "Kees Cook" <keescook@chromium.org>,
"Daniel P. Berrangé" <berrange@redhat.com>,
"Jeff Layton" <jlayton@redhat.com>,
"Miklos Szeredi" <miklos@szeredi.hu>,
"Matthew Wilcox" <willy@debian.org>,
"J. Bruce Fields" <bfields@fieldses.org>,
"Matthew Wilcox" <matthew@wil.cx>,
"Trond Myklebust" <trond.myklebust@fys.uio.no>,
"Chris Wright" <chrisw@redhat.com>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Martin KaFai Lau" <kafai@fb.com>,
"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
"Andrii Nakryiko" <andriin@fb.com>,
"John Fastabend" <john.fastabend@gmail.com>,
"KP Singh" <kpsingh@chromium.org>,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: [PATCH 13/17] file: Remove get_files_struct
Date: Mon, 17 Aug 2020 17:04:21 -0500 [thread overview]
Message-ID: <20200817220425.9389-13-ebiederm@xmission.com> (raw)
In-Reply-To: <87ft8l6ic3.fsf@x220.int.ebiederm.org>
When discussing[1] exec and posix file locks it was realized that none
of the callers of get_files_struct fundamentally needed to call
get_files_struct, and that by switching them to helper functions
instead it will both simplify their code and remove unnecessary
increments of files_struct.count. Those unnecessary increments can
result in exec unnecessarily unsharing files_struct which breaking
posix locks, and it can result in fget_light having to fallback to
fget reducing system performance.
Now that get_files_struct has no more users and can not cause the
problems for posix file locking and fget_light remove get_files_struct
so that it does not gain any new users.
[1] https://lkml.kernel.org/r/20180915160423.GA31461@redhat.com
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/file.c | 13 -------------
include/linux/fdtable.h | 1 -
2 files changed, 14 deletions(-)
diff --git a/fs/file.c b/fs/file.c
index 88f9f78869f8..605e756f3c63 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -410,19 +410,6 @@ static struct fdtable *close_files(struct files_struct * files)
return fdt;
}
-struct files_struct *get_files_struct(struct task_struct *task)
-{
- struct files_struct *files;
-
- task_lock(task);
- files = task->files;
- if (files)
- atomic_inc(&files->count);
- task_unlock(task);
-
- return files;
-}
-
void put_files_struct(struct files_struct *files)
{
if (atomic_dec_and_test(&files->count)) {
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index a3a054084f49..8c4bc6aa19c9 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -108,7 +108,6 @@ struct file *fnext_task(struct task_struct *task, unsigned int *fd);
struct task_struct;
-struct files_struct *get_files_struct(struct task_struct *);
void put_files_struct(struct files_struct *fs);
int unshare_files(void);
struct files_struct *dup_fd(struct files_struct *, unsigned, int *) __latent_entropy;
--
2.25.0
next prev parent reply other threads:[~2020-08-17 22:12 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-17 22:03 exec: Move unshare_files and guarantee files_struct.count is correct Eric W. Biederman
2020-08-17 22:04 ` [PATCH 01/17] exec: Move unshare_files to fix posix file locking during exec Eric W. Biederman
2020-08-18 10:04 ` Christian Brauner
2020-08-17 22:04 ` [PATCH 02/17] exec: Simplify unshare_files Eric W. Biederman
2020-08-18 10:08 ` Christian Brauner
2020-08-17 22:04 ` [PATCH 03/17] exec: Remove reset_files_struct Eric W. Biederman
2020-08-18 10:09 ` Christian Brauner
2020-08-17 22:04 ` [PATCH 04/17] kcmp: In kcmp_epoll_target use fget_task Eric W. Biederman
2020-08-20 21:45 ` Cyrill Gorcunov
2020-08-17 22:04 ` [PATCH 05/17] bpf: In bpf_task_fd_query " Eric W. Biederman
2020-08-17 22:04 ` [PATCH 06/17] file: Implement fcheck_task Eric W. Biederman
2020-08-18 10:37 ` Christian Brauner
2020-08-17 22:04 ` [PATCH 07/17] proc/fd: In tid_fd_mode use fcheck_task Eric W. Biederman
2020-08-18 10:36 ` Christian Brauner
2020-08-17 22:04 ` [PATCH 08/17] proc/fd: In proc_fd_link " Eric W. Biederman
2020-08-18 10:36 ` Christian Brauner
2020-08-17 22:04 ` [PATCH 09/17] file: Implement fnext_task Eric W. Biederman
2020-08-17 23:54 ` Linus Torvalds
[not found] ` <875z9g7oln.fsf@x220.int.ebiederm.org>
2020-08-18 1:17 ` Linus Torvalds
2020-08-18 11:05 ` Christian Brauner
[not found] ` <87pn7m22kn.fsf@x220.int.ebiederm.org>
2020-08-19 15:54 ` Alexei Starovoitov
[not found] ` <871rk0t45v.fsf@x220.int.ebiederm.org>
2020-08-21 16:17 ` Alexei Starovoitov
2020-08-19 18:32 ` Linus Torvalds
2020-08-20 21:50 ` Cyrill Gorcunov
2020-08-17 22:04 ` [PATCH 10/17] proc/fd: In proc_readfd_common use fnext_task Eric W. Biederman
2020-08-18 2:22 ` Al Viro
[not found] ` <87sgck4o23.fsf@x220.int.ebiederm.org>
2020-08-18 4:59 ` Alexei Starovoitov
2020-08-17 22:04 ` [PATCH 11/17] bpf/task_iter: In task_file_seq_get_next " Eric W. Biederman
2020-08-18 5:39 ` kernel test robot
2020-08-18 12:54 ` Eric W. Biederman
2020-08-17 22:04 ` [PATCH 12/17] proc/fd: In fdinfo seq_show don't use get_files_struct Eric W. Biederman
2020-08-18 0:08 ` Linus Torvalds
[not found] ` <87v9hg69ph.fsf@x220.int.ebiederm.org>
2020-08-18 1:21 ` Linus Torvalds
2020-08-18 10:43 ` Christian Brauner
2020-08-17 22:04 ` Eric W. Biederman [this message]
2020-08-18 10:39 ` [PATCH 13/17] file: Remove get_files_struct Christian Brauner
2020-08-17 22:04 ` [PATCH 14/17] file: Merge __fd_install into fd_install Eric W. Biederman
2020-08-18 10:15 ` Christian Brauner
2020-08-17 22:04 ` [PATCH 15/17] file: In f_dupfd read RLIMIT_NOFILE once Eric W. Biederman
2020-08-18 10:12 ` Christian Brauner
2020-08-17 22:04 ` [PATCH 16/17] file: Merge __alloc_fd into alloc_fd Eric W. Biederman
2020-08-18 10:17 ` Christian Brauner
2020-08-17 22:04 ` [PATCH 17/17] file: Rename __close_fd to close_fd and remove the files parameter Eric W. Biederman
2020-08-18 10:19 ` Christian Brauner
2020-08-18 11:20 ` Christoph Hellwig
2020-08-18 12:48 ` Eric W. Biederman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200817220425.9389-13-ebiederm@xmission.com \
--to=ebiederm@xmission.com \
--cc=andriin@fb.com \
--cc=ast@kernel.org \
--cc=berrange@redhat.com \
--cc=bfields@fieldses.org \
--cc=bpf@vger.kernel.org \
--cc=christian.brauner@ubuntu.com \
--cc=chrisw@redhat.com \
--cc=criu@openvz.org \
--cc=daniel@iogearbox.net \
--cc=gorcunov@gmail.com \
--cc=jann@thejh.net \
--cc=jlayton@redhat.com \
--cc=john.fastabend@gmail.com \
--cc=kafai@fb.com \
--cc=keescook@chromium.org \
--cc=kpsingh@chromium.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=matthew@wil.cx \
--cc=miklos@szeredi.hu \
--cc=oleg@redhat.com \
--cc=songliubraving@fb.com \
--cc=torvalds@linux-foundation.org \
--cc=trond.myklebust@fys.uio.no \
--cc=viro@zeniv.linux.org.uk \
--cc=willy@debian.org \
--cc=yhs@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).