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authorAl Viro <viro@zeniv.linux.org.uk>2014-08-07 08:39:04 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2014-08-07 14:40:08 -0400
commitefb170c22867cdc6f770de441bdefecec6712199 (patch)
tree6427257fe101016ef07ba28903d65d8f8be8e2ca /kernel
parent1629d0eb3ead0e0c49e4402049ec7b5b31b81cd7 (diff)
take fs_pin stuff to fs/*
Add a new field to fs_pin - kill(pin). That's what umount and r/o remount will be calling for all pins attached to vfsmount and superblock resp. Called after bumping the refcount, so it won't go away under us. Dropping the refcount is responsibility of the instance. All generic stuff moved to fs/fs_pin.c; the next step will rip all the knowledge of kernel/acct.c from fs/super.c and fs/namespace.c. After that - death to mnt_pin(); it was intended to be usable as generic mechanism for code that wants to attach objects to vfsmount, so that they would not make the sucker busy and would get killed on umount. Never got it right; it remained acct.c-specific all along. Now it's very close to being killable. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/acct.c127
1 files changed, 32 insertions, 95 deletions
diff --git a/kernel/acct.c b/kernel/acct.c
index afeaaa6f49bf..a7993a6cb604 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -59,7 +59,7 @@
#include <asm/div64.h>
#include <linux/blkdev.h> /* sector_div */
#include <linux/pid_namespace.h>
-#include <../fs/mount.h> /* will go away when we refactor */
+#include <linux/fs_pin.h>
/*
* These constants control the amount of freespace that suspend and
@@ -78,17 +78,6 @@ int acct_parm[3] = {4, 2, 30};
*/
static void do_acct_process(struct bsd_acct_struct *acct);
-struct fs_pin {
- atomic_long_t count;
- union {
- struct {
- struct hlist_node s_list;
- struct hlist_node m_list;
- };
- struct rcu_head rcu;
- };
-};
-
struct bsd_acct_struct {
struct fs_pin pin;
struct mutex lock;
@@ -100,13 +89,6 @@ struct bsd_acct_struct {
struct completion done;
};
-static void pin_free_rcu(struct rcu_head *head)
-{
- kfree(container_of(head, struct fs_pin, rcu));
-}
-
-static DEFINE_SPINLOCK(acct_lock);
-
/*
* Check the amount of free space and suspend/resume accordingly.
*/
@@ -142,29 +124,6 @@ out:
return acct->active;
}
-static void pin_put(struct fs_pin *p)
-{
- if (atomic_long_dec_and_test(&p->count))
- call_rcu(&p->rcu, pin_free_rcu);
-}
-
-static struct bsd_acct_struct *__acct_get(struct bsd_acct_struct *res)
-{
- if (!atomic_long_inc_not_zero(&res->pin.count)) {
- rcu_read_unlock();
- cpu_relax();
- return NULL;
- }
- rcu_read_unlock();
- mutex_lock(&res->lock);
- if (!res->ns) {
- mutex_unlock(&res->lock);
- pin_put(&res->pin);
- return NULL;
- }
- return res;
-}
-
static struct bsd_acct_struct *acct_get(struct pid_namespace *ns)
{
struct bsd_acct_struct *res;
@@ -176,9 +135,18 @@ again:
rcu_read_unlock();
return NULL;
}
- res = __acct_get(res);
- if (!res)
+ if (!atomic_long_inc_not_zero(&res->pin.count)) {
+ rcu_read_unlock();
+ cpu_relax();
goto again;
+ }
+ rcu_read_unlock();
+ mutex_lock(&res->lock);
+ if (!res->ns) {
+ mutex_unlock(&res->lock);
+ pin_put(&res->pin);
+ goto again;
+ }
return res;
}
@@ -203,19 +171,8 @@ static void acct_kill(struct bsd_acct_struct *acct,
init_completion(&acct->done);
schedule_work(&acct->work);
wait_for_completion(&acct->done);
- spin_lock(&acct_lock);
- hlist_del(&acct->pin.m_list);
- hlist_del(&acct->pin.s_list);
- spin_unlock(&acct_lock);
+ pin_remove(&acct->pin);
ns->bacct = new;
- if (new) {
- struct vfsmount *m = new->file->f_path.mnt;
- spin_lock(&acct_lock);
- hlist_add_head(&new->pin.s_list, &m->mnt_sb->s_pins);
- hlist_add_head(&new->pin.m_list, &real_mount(m)->mnt_pins);
- spin_unlock(&acct_lock);
- mutex_unlock(&new->lock);
- }
acct->ns = NULL;
atomic_long_dec(&acct->pin.count);
mutex_unlock(&acct->lock);
@@ -223,6 +180,19 @@ static void acct_kill(struct bsd_acct_struct *acct,
}
}
+static void acct_pin_kill(struct fs_pin *pin)
+{
+ struct bsd_acct_struct *acct;
+ acct = container_of(pin, struct bsd_acct_struct, pin);
+ mutex_lock(&acct->lock);
+ if (!acct->ns) {
+ mutex_unlock(&acct->lock);
+ pin_put(pin);
+ acct = NULL;
+ }
+ acct_kill(acct, NULL);
+}
+
static int acct_on(struct filename *pathname)
{
struct file *file;
@@ -254,25 +224,22 @@ static int acct_on(struct filename *pathname)
}
atomic_long_set(&acct->pin.count, 1);
+ acct->pin.kill = acct_pin_kill;
acct->file = file;
acct->needcheck = jiffies;
acct->ns = ns;
mutex_init(&acct->lock);
mnt = file->f_path.mnt;
mnt_pin(mnt);
+ mutex_lock_nested(&acct->lock, 1); /* nobody has seen it yet */
+ pin_insert(&acct->pin, mnt);
old = acct_get(ns);
- mutex_lock_nested(&acct->lock, 1); /* nobody has seen it yet */
- if (old) {
+ if (old)
acct_kill(old, acct);
- } else {
+ else
ns->bacct = acct;
- spin_lock(&acct_lock);
- hlist_add_head(&acct->pin.s_list, &mnt->mnt_sb->s_pins);
- hlist_add_head(&acct->pin.m_list, &real_mount(mnt)->mnt_pins);
- spin_unlock(&acct_lock);
- mutex_unlock(&acct->lock);
- }
+ mutex_unlock(&acct->lock);
mntput(mnt); /* it's pinned, now give up active reference */
return 0;
}
@@ -312,36 +279,6 @@ SYSCALL_DEFINE1(acct, const char __user *, name)
return error;
}
-void acct_auto_close_mnt(struct hlist_head *list)
-{
- rcu_read_lock();
- while (1) {
- struct hlist_node *p = ACCESS_ONCE(list->first);
- if (!p)
- break;
- acct_kill(__acct_get(hlist_entry(p,
- struct bsd_acct_struct,
- pin.m_list)), NULL);
- rcu_read_lock();
- }
- rcu_read_unlock();
-}
-
-void acct_auto_close(struct hlist_head *list)
-{
- rcu_read_lock();
- while (1) {
- struct hlist_node *p = ACCESS_ONCE(list->first);
- if (!p)
- break;
- acct_kill(__acct_get(hlist_entry(p,
- struct bsd_acct_struct,
- pin.s_list)), NULL);
- rcu_read_lock();
- }
- rcu_read_unlock();
-}
-
void acct_exit_ns(struct pid_namespace *ns)
{
acct_kill(acct_get(ns), NULL);