[Devel] [PATCH 7/28] [PREP 7/14] Prepare proc_flust_task to flush entries from multiple proc trees

[Pavel Emelianov]

Since a task will appear in more than one proc tree we need to shrink many
trees. For this case we pass the struct pid to proc_flush_task() and shrink
the mounts of all the namespaces this pid belongs to.

The NULL passed to it means that only global mount is to be flushed.

Signed-off-by: Pavel Emelianov <xemul at openvz.org>

---

 fs/proc/base.c          |   25 ++++++++++++++++++++++---
 include/linux/proc_fs.h |    6 ++++--
 kernel/exit.c           |    2 +-
 3 files changed, 27 insertions(+), 6 deletions(-)

--- ./fs/proc/base.c.procflushtask	2007-06-15 15:02:29.000000000 +0400
+++ ./fs/proc/base.c	2007-06-15 15:04:18.000000000 +0400
@@ -2184,7 +2184,7 @@ static const struct inode_operations pro
  *       that no dcache entries will exist at process exit time it
  *       just makes it very unlikely that any will persist.
  */
-void proc_flush_task(struct task_struct *task)
+static void proc_flush_task_mnt(struct task_struct *task, struct vfsmount *mnt)
 {
 	struct dentry *dentry, *leader, *dir;
 	char buf[PROC_NUMBUF];
@@ -2192,7 +2192,7 @@ void proc_flush_task(struct task_struct 
 
 	name.name = buf;
 	name.len = snprintf(buf, sizeof(buf), "%d", task->pid);
-	dentry = d_hash_and_lookup(proc_mnt->mnt_root, &name);
+	dentry = d_hash_and_lookup(mnt->mnt_root, &name);
 	if (dentry) {
 		shrink_dcache_parent(dentry);
 		d_drop(dentry);
@@ -2204,7 +2204,7 @@ void proc_flush_task(struct task_struct 
 
 	name.name = buf;
 	name.len = snprintf(buf, sizeof(buf), "%d", task->tgid);
-	leader = d_hash_and_lookup(proc_mnt->mnt_root, &name);
+	leader = d_hash_and_lookup(mnt->mnt_root, &name);
 	if (!leader)
 		goto out;
 
@@ -2230,6 +2230,25 @@ out:
 	return;
 }
 
+/*
+ * when flushing dentries from proc one need to flush them from global
+ * proc (proc_mnt) and from all the namespaces' procs this task was seen
+ * in. this call is supposed to make all this job.
+ */
+#ifndef CONFIG_PID_NS
+static inline void proc_flush_task_ns(struct task_struct *tsk, struct pid *pid)
+{
+}
+#else
+#endif
+
+void proc_flush_task(struct task_struct *task, struct pid *pid)
+{
+	proc_flush_task_mnt(task, proc_mnt);
+	if (pid != NULL)
+		proc_flush_task_ns(task, pid);
+}
+
 static struct dentry *proc_pid_instantiate(struct inode *dir,
 					   struct dentry * dentry,
 					   struct task_struct *task, const void *ptr)
--- ./include/linux/proc_fs.h.procflushtask	2007-06-15 15:00:32.000000000 +0400
+++ ./include/linux/proc_fs.h	2007-06-15 15:03:10.000000000 +0400
@@ -111,7 +111,7 @@ extern void proc_misc_init(void);
 
 struct mm_struct;
 
-void proc_flush_task(struct task_struct *task);
+void proc_flush_task(struct task_struct *task, struct pid *pid);
 struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *);
 int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir);
 unsigned long task_vsize(struct mm_struct *);
@@ -223,7 +223,9 @@ static inline void proc_net_remove(const
 #define proc_net_create(name, mode, info)	({ (void)(mode), NULL; })
 static inline void proc_net_remove(const char *name) {}
 
-static inline void proc_flush_task(struct task_struct *task) { }
+static inline void proc_flush_task(struct task_struct *task, struct pid *pid)
+{
+}
 
 static inline struct proc_dir_entry *create_proc_entry(const char *name,
 	mode_t mode, struct proc_dir_entry *parent) { return NULL; }
--- ./kernel/exit.c.procflushtask	2007-06-15 15:02:29.000000000 +0400
+++ ./kernel/exit.c	2007-06-15 15:03:10.000000000 +0400
@@ -185,7 +185,7 @@ repeat:
 	}
 
 	write_unlock_irq(&tasklist_lock);
-	proc_flush_task(p);
+	proc_flush_task(p, NULL);
 	release_thread(p);
 	call_rcu(&p->rcu, delayed_put_task_struct);
 
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