| Message ID | 20200817220425.9389-13-ebiederm@xmission.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/17] exec: Move unshare_files to fix posix file locking during exec | expand |
On Mon, Aug 17, 2020 at 05:04:21PM -0500, Eric W. Biederman wrote: > 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> > --- Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
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;
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(-)