proc: introduce proc_mem_open()

Extract the mm_access() code from __mem_open() into the new helper,
proc_mem_open(), the next patch will add another caller.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index baf852b..4c542b9 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -632,29 +632,35 @@ static const struct file_operations proc_single_file_operations = {
        .release        = single_release,
 };
 
-static int __mem_open(struct inode *inode, struct file *file, unsigned int mode)
+
+struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode)
 {
-       struct task_struct *task = get_proc_task(file_inode(file));
-       struct mm_struct *mm;
+       struct task_struct *task = get_proc_task(inode);
+       struct mm_struct *mm = ERR_PTR(-ESRCH);
 
-       if (!task)
-               return -ESRCH;
+       if (task) {
+               mm = mm_access(task, mode);
+               put_task_struct(task);
 
-       mm = mm_access(task, mode);
-       put_task_struct(task);
+               if (!IS_ERR_OR_NULL(mm)) {
+                       /* ensure this mm_struct can't be freed */
+                       atomic_inc(&mm->mm_count);
+                       /* but do not pin its memory */
+                       mmput(mm);
+               }
+       }
+
+       return mm;
+}
+
+static int __mem_open(struct inode *inode, struct file *file, unsigned int mode)
+{
+       struct mm_struct *mm = proc_mem_open(inode, mode);
 
        if (IS_ERR(mm))
                return PTR_ERR(mm);
 
-       if (mm) {
-               /* ensure this mm_struct can't be freed */
-               atomic_inc(&mm->mm_count);
-               /* but do not pin its memory */
-               mmput(mm);
-       }
-
        file->private_data = mm;
-
        return 0;
 }
 

diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 7da13e4..3c68556 100644 (file)
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -278,6 +278,8 @@ struct proc_maps_private {
 #endif
 };
 
+struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode);
+
 extern const struct file_operations proc_pid_maps_operations;
 extern const struct file_operations proc_tid_maps_operations;
 extern const struct file_operations proc_pid_numa_maps_operations;