mm: rcu-protected get_mm_exe_file()
This patch removes mm->mmap_sem from mm->exe_file read side.
Also it kills dup_mm_exe_file() and moves exe_file duplication into
dup_mmap() where both mmap_sems are locked.
[akpm@linux-foundation.org: fix comment typo]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/file.c b/fs/file.c
index ee738ea..93c5f89 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -638,8 +638,7 @@
file = fcheck_files(files, fd);
if (file) {
/* File object ref couldn't be taken */
- if ((file->f_mode & mask) ||
- !atomic_long_inc_not_zero(&file->f_count))
+ if ((file->f_mode & mask) || !get_file_rcu(file))
file = NULL;
}
rcu_read_unlock();