[PATCH 4/5] fs/proc/task_mmu.c: introduce the "stable" proc_maps_private->mm

[Oleg Nesterov]

A separate change to simplify the review of the next one.

Add the new "mm_struct *mm" member into struct proc_maps_private, it is
initialized by proc_maps_open() at "open" time.

This obviously means that proc_maps_open() users should additionally do
mmdrop() in fop->release(), add the new helper, proc_map_release().

Signed-off-by: Oleg Nesterov <o...@redhat.com>
---
 fs/proc/internal.h |    1 +
 fs/proc/task_mmu.c |   31 +++++++++++++++++++++++++------
 2 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index ba0c1c1..78784cd 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -267,6 +267,7 @@ extern int proc_remount(struct super_block *, int *, char 
*);
 struct proc_maps_private {
        struct pid *pid;
        struct task_struct *task;
+       struct mm_struct *mm;
 #ifdef CONFIG_MMU
        struct vm_area_struct *tail_vma;
 #endif
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 794aeb6..1cc623d 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -240,9 +240,28 @@ static int proc_maps_open(struct inode *inode, struct file 
*file,
                return -ENOMEM;
 
        priv->pid = proc_pid(inode);
+       priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
+       if (IS_ERR(priv->mm)) {
+               int err = PTR_ERR(priv->mm);
+               seq_release_private(inode, file);
+               return err;
+       }
+
        return 0;
 }
 
+static int proc_map_release(struct inode *inode, struct file *file)
+{
+       struct seq_file *seq = file->private_data;
+       struct proc_maps_private *priv = seq->private;
+
+       if (priv->mm)
+               mmdrop(priv->mm);
+
+       return seq_release_private(inode, file);
+}
+
+
 static int do_maps_open(struct inode *inode, struct file *file,
                        const struct seq_operations *ops)
 {
@@ -398,14 +417,14 @@ const struct file_operations proc_pid_maps_operations = {
        .open           = pid_maps_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
-       .release        = seq_release_private,
+       .release        = proc_map_release,
 };
 
 const struct file_operations proc_tid_maps_operations = {
        .open           = tid_maps_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
-       .release        = seq_release_private,
+       .release        = proc_map_release,
 };
 
 /*
@@ -680,14 +699,14 @@ const struct file_operations proc_pid_smaps_operations = {
        .open           = pid_smaps_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
-       .release        = seq_release_private,
+       .release        = proc_map_release,
 };
 
 const struct file_operations proc_tid_smaps_operations = {
        .open           = tid_smaps_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
-       .release        = seq_release_private,
+       .release        = proc_map_release,
 };
 
 /*
@@ -1520,13 +1539,13 @@ const struct file_operations 
proc_pid_numa_maps_operations = {
        .open           = pid_numa_maps_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
-       .release        = seq_release_private,
+       .release        = proc_map_release,
 };
 
 const struct file_operations proc_tid_numa_maps_operations = {
        .open           = tid_numa_maps_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
-       .release        = seq_release_private,
+       .release        = proc_map_release,
 };
 #endif /* CONFIG_NUMA */
-- 
1.5.5.1


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/