[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>
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 41ecbb8..e127ef7 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -119,7 +119,6 @@
.signal = {{0}}}, \
.blocked = {{0}}, \
.alloc_lock = SPIN_LOCK_UNLOCKED, \
- .proc_lock = SPIN_LOCK_UNLOCKED, \
.journal_info = NULL, \
.cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \
.fs_excl = ATOMIC_INIT(0), \
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 9dd8488..d4d2081 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -99,9 +99,8 @@
struct mm_struct;
+void proc_flush_task(struct task_struct *task);
struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *);
-struct dentry *proc_pid_unhash(struct task_struct *p);
-void proc_pid_flush(struct dentry *proc_dentry);
int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir);
unsigned long task_vsize(struct mm_struct *);
int task_statm(struct mm_struct *, int *, int *, int *, int *);
@@ -211,8 +210,7 @@
#define proc_net_create(name, mode, info) ({ (void)(mode), NULL; })
static inline void proc_net_remove(const char *name) {}
-static inline struct dentry *proc_pid_unhash(struct task_struct *p) { return NULL; }
-static inline void proc_pid_flush(struct dentry *proc_dentry) { }
+static inline void proc_flush_task(struct task_struct *task) { }
static inline struct proc_dir_entry *create_proc_entry(const char *name,
mode_t mode, struct proc_dir_entry *parent) { return NULL; }
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8d11d93..122a25c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -842,8 +842,6 @@
u32 self_exec_id;
/* Protection of (de-)allocation: mm, files, fs, tty, keyrings */
spinlock_t alloc_lock;
-/* Protection of proc_dentry: nesting proc_lock, dcache_lock, write_lock_irq(&tasklist_lock); */
- spinlock_t proc_lock;
#ifdef CONFIG_DEBUG_MUTEXES
/* mutex deadlock detection */
@@ -856,7 +854,6 @@
/* VM state */
struct reclaim_state *reclaim_state;
- struct dentry *proc_dentry;
struct backing_dev_info *backing_dev_info;
struct io_context *io_context;