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Subject[PATCH 8/10] Bsdacct: switch from global bsd_acct_struct instance to per-pidns one
Allocate the structure on the first call to sys_acct(). After
this each namespace, that ordered the accounting, will live
with this structure till its own death.

Two notes
- routines, that close the accounting on fs umount time use
the init_pid_ns's acct by now;
- accounting routine accounts to dying task's namespace
(also by now).

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
---
include/linux/acct.h | 3 ++
kernel/acct.c | 84 +++++++++++++++++++++++++++++++++++++----------
kernel/pid_namespace.c | 2 +
3 files changed, 71 insertions(+), 18 deletions(-)
diff --git a/include/linux/acct.h b/include/linux/acct.h
index e8cae54..882dc72 100644
--- a/include/linux/acct.h
+++ b/include/linux/acct.h
@@ -120,17 +120,20 @@ struct acct_v3
struct vfsmount;
struct super_block;
struct pacct_struct;
+struct pid_namespace;
extern void acct_auto_close_mnt(struct vfsmount *m);
extern void acct_auto_close(struct super_block *sb);
extern void acct_init_pacct(struct pacct_struct *pacct);
extern void acct_collect(long exitcode, int group_dead);
extern void acct_process(void);
+extern void acct_exit_ns(struct pid_namespace *);
#else
#define acct_auto_close_mnt(x) do { } while (0)
#define acct_auto_close(x) do { } while (0)
#define acct_init_pacct(x) do { } while (0)
#define acct_collect(x,y) do { } while (0)
#define acct_process() do { } while (0)
+#define acct_exit_ns(ns) do { } while (0)
#endif

/*
diff --git a/kernel/acct.c b/kernel/acct.c
index 72d4760..febbbc6 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -93,8 +93,6 @@ struct bsd_acct_struct {

static DEFINE_SPINLOCK(acct_lock);

-static struct bsd_acct_struct acct_globals __cacheline_aligned;
-
/*
* Called whenever the timer says to check the free space.
*/
@@ -176,7 +174,8 @@ out:
*
* NOTE: acct_lock MUST be held on entry and exit.
*/
-static void acct_file_reopen(struct bsd_acct_struct *acct, struct file *file)
+static void acct_file_reopen(struct bsd_acct_struct *acct, struct file *file,
+ struct pid_namespace *ns)
{
struct file *old_acct = NULL;
struct pid_namespace *old_ns = NULL;
@@ -188,10 +187,11 @@ static void acct_file_reopen(struct bsd_acct_struct *acct, struct file *file)
acct->active = 0;
acct->needcheck = 0;
acct->file = NULL;
+ acct->ns = NULL;
}
if (file) {
acct->file = file;
- acct->ns = get_pid_ns(task_active_pid_ns(current));
+ acct->ns = ns;
acct->needcheck = 0;
acct->active = 1;
/* It's been deleted if it was used before so this is safe */
@@ -204,7 +204,6 @@ static void acct_file_reopen(struct bsd_acct_struct *acct, struct file *file)
spin_unlock(&acct_lock);
do_acct_process(acct, old_ns, old_acct);
filp_close(old_acct, NULL);
- put_pid_ns(old_ns);
spin_lock(&acct_lock);
}
}
@@ -213,6 +212,8 @@ static int acct_on(char *name)
{
struct file *file;
int error;
+ struct pid_namespace *ns;
+ struct bsd_acct_struct *acct = NULL;

/* Difference from BSD - they don't do O_APPEND */
file = filp_open(name, O_WRONLY|O_APPEND|O_LARGEFILE, 0);
@@ -229,18 +230,34 @@ static int acct_on(char *name)
return -EIO;
}

+ ns = task_active_pid_ns(current);
+ if (ns->bacct == NULL) {
+ acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL);
+ if (acct == NULL) {
+ filp_close(file, NULL);
+ return -ENOMEM;
+ }
+ }
+
error = security_acct(file);
if (error) {
+ kfree(acct);
filp_close(file, NULL);
return error;
}

spin_lock(&acct_lock);
+ if (ns->bacct == NULL) {
+ ns->bacct = acct;
+ acct = NULL;
+ }
+
mnt_pin(file->f_path.mnt);
- acct_file_reopen(&acct_globals, file);
+ acct_file_reopen(ns->bacct, file, ns);
spin_unlock(&acct_lock);

mntput(file->f_path.mnt); /* it's pinned, now give up active reference */
+ kfree(acct);

return 0;
}
@@ -270,10 +287,16 @@ asmlinkage long sys_acct(const char __user *name)
error = acct_on(tmp);
putname(tmp);
} else {
+ struct bsd_acct_struct *acct;
+
+ acct = task_active_pid_ns(current)->bacct;
+ if (acct == NULL)
+ return 0;
+
error = security_acct(NULL);
if (!error) {
spin_lock(&acct_lock);
- acct_file_reopen(&acct_globals, NULL);
+ acct_file_reopen(acct, NULL, NULL);
spin_unlock(&acct_lock);
}
}
@@ -289,9 +312,15 @@ asmlinkage long sys_acct(const char __user *name)
*/
void acct_auto_close_mnt(struct vfsmount *m)
{
+ struct bsd_acct_struct *acct;
+
+ acct = init_pid_ns.bacct;
+ if (acct == NULL)
+ return;
+
spin_lock(&acct_lock);
- if (acct_globals.file && acct_globals.file->f_path.mnt == m)
- acct_file_reopen(&acct_globals, NULL);
+ if (acct->file && acct->file->f_path.mnt == m)
+ acct_file_reopen(acct, NULL, NULL);
spin_unlock(&acct_lock);
}

@@ -304,10 +333,29 @@ void acct_auto_close_mnt(struct vfsmount *m)
*/
void acct_auto_close(struct super_block *sb)
{
+ struct bsd_acct_struct *acct;
+
+ acct = init_pid_ns.bacct;
+ if (acct == NULL)
+ return;
+
spin_lock(&acct_lock);
- if (acct_globals.file &&
- acct_globals.file->f_path.mnt->mnt_sb == sb) {
- acct_file_reopen(&acct_globals, NULL);
+ if (acct->file && acct->file->f_path.mnt->mnt_sb == sb)
+ acct_file_reopen(acct, NULL, NULL);
+ spin_unlock(&acct_lock);
+}
+
+void acct_exit_ns(struct pid_namespace *ns)
+{
+ struct bsd_acct_struct *acct;
+
+ spin_lock(&acct_lock);
+ acct = ns->bacct;
+ if (acct != NULL) {
+ if (acct->file != NULL)
+ acct_file_reopen(acct, NULL, NULL);
+
+ kfree(acct);
}
spin_unlock(&acct_lock);
}
@@ -587,25 +635,25 @@ void acct_collect(long exitcode, int group_dead)
void acct_process(void)
{
struct file *file = NULL;
- struct pid_namespace *ns;
+ struct pid_namespace *ns = task_active_pid_ns(current);
+ struct bsd_acct_struct *acct;

+ acct = ns->bacct;
/*
* accelerate the common fastpath:
*/
- if (!acct_globals.file)
+ if (!acct || !acct->file)
return;

spin_lock(&acct_lock);
- file = acct_globals.file;
+ file = acct->file;
if (unlikely(!file)) {
spin_unlock(&acct_lock);
return;
}
get_file(file);
- ns = get_pid_ns(acct_globals.ns);
spin_unlock(&acct_lock);

- do_acct_process(&acct_globals, ns, file);
+ do_acct_process(acct, ns, file);
fput(file);
- put_pid_ns(ns);
}
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 06331cc..ea567b7 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -12,6 +12,7 @@
#include <linux/pid_namespace.h>
#include <linux/syscalls.h>
#include <linux/err.h>
+#include <linux/acct.h>

#define BITS_PER_PAGE (PAGE_SIZE*8)

@@ -181,6 +182,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)

/* Child reaper for the pid namespace is going away */
pid_ns->child_reaper = NULL;
+ acct_exit_ns(pid_ns);
return;
}

--
1.5.3.4

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