[PATCH] proc: Rewrite the proc dentry flush on exit optimization

To keep the dcache from filling up with dead /proc entries we flush them on
process exit.  However over the years that code has gotten hairy with a
dentry_pointer and a lock in task_struct and misdocumented as a correctness
feature.

I have rewritten this code to look and see if we have a corresponding entry in
the dcache and if so flush it on process exit.  This removes the extra fields
in the task_struct and allows me to trivially handle the case of a
/proc/<tgid>/task/<pid> entry as well as the current /proc/<pid> entries.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 0 insertions, 10 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 0b88bf646143..8c5196087f31 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -666,8 +666,6 @@ static int de_thread(struct task_struct *tsk)
          * and to assume its PID:
          */
         if (!thread_group_leader(current)) {
-                struct dentry *proc_dentry1, *proc_dentry2;
-
                 /*
                  * Wait for the thread group leader to be a zombie.
                  * It should already be zombie at this point, most
@@ -689,10 +687,6 @@ static int de_thread(struct task_struct *tsk)
                  */
                 current->start_time = leader->start_time;
 
-                spin_lock(&leader->proc_lock);
-                spin_lock(&current->proc_lock);
-                proc_dentry1 = proc_pid_unhash(current);
-                proc_dentry2 = proc_pid_unhash(leader);
                 write_lock_irq(&tasklist_lock);
 
                 BUG_ON(leader->tgid != current->tgid);
@@ -729,10 +723,6 @@ static int de_thread(struct task_struct *tsk)
                 leader->exit_state = EXIT_DEAD;
 
                 write_unlock_irq(&tasklist_lock);
-                spin_unlock(&leader->proc_lock);
-                spin_unlock(&current->proc_lock);
-                proc_pid_flush(proc_dentry1);
-                proc_pid_flush(proc_dentry2);
         }
 
         /*