diff options
author | Al Viro <viro@zeniv.linux.org.uk> | 2015-01-11 01:53:21 +0300 |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2015-01-26 07:17:28 +0300 |
commit | 59eda0e07f43c950d31756213b607af673e551f0 (patch) | |
tree | f40f7b67133576c36a65a4cba9aca5df68d00f34 /kernel/acct.c | |
parent | fdab684d7202774bfd8762d4a656a553b787c8ec (diff) |
new fs_pin killing logics
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'kernel/acct.c')
-rw-r--r-- | kernel/acct.c | 81 |
1 files changed, 34 insertions, 47 deletions
diff --git a/kernel/acct.c b/kernel/acct.c index cf6588ab517b..e6c10d1a4058 100644 --- a/kernel/acct.c +++ b/kernel/acct.c @@ -76,7 +76,6 @@ int acct_parm[3] = {4, 2, 30}; /* * External references and all of the globals. */ -static void do_acct_process(struct bsd_acct_struct *acct); struct bsd_acct_struct { struct fs_pin pin; @@ -91,6 +90,8 @@ struct bsd_acct_struct { struct completion done; }; +static void do_acct_process(struct bsd_acct_struct *acct); + /* * Check the amount of free space and suspend/resume accordingly. */ @@ -132,13 +133,18 @@ static void acct_put(struct bsd_acct_struct *p) kfree_rcu(p, rcu); } +static inline struct bsd_acct_struct *to_acct(struct fs_pin *p) +{ + return p ? container_of(p, struct bsd_acct_struct, pin) : NULL; +} + static struct bsd_acct_struct *acct_get(struct pid_namespace *ns) { struct bsd_acct_struct *res; again: smp_rmb(); rcu_read_lock(); - res = ACCESS_ONCE(ns->bacct); + res = to_acct(ACCESS_ONCE(ns->bacct)); if (!res) { rcu_read_unlock(); return NULL; @@ -150,7 +156,7 @@ again: } rcu_read_unlock(); mutex_lock(&res->lock); - if (!res->ns) { + if (res != to_acct(ACCESS_ONCE(ns->bacct))) { mutex_unlock(&res->lock); acct_put(res); goto again; @@ -158,6 +164,19 @@ again: return res; } +static void acct_pin_kill(struct fs_pin *pin) +{ + struct bsd_acct_struct *acct = to_acct(pin); + mutex_lock(&acct->lock); + do_acct_process(acct); + schedule_work(&acct->work); + wait_for_completion(&acct->done); + cmpxchg(&acct->ns->bacct, pin, NULL); + mutex_unlock(&acct->lock); + pin_remove(pin); + acct_put(acct); +} + static void close_work(struct work_struct *work) { struct bsd_acct_struct *acct = container_of(work, struct bsd_acct_struct, work); @@ -168,49 +187,13 @@ static void close_work(struct work_struct *work) complete(&acct->done); } -static void acct_kill(struct bsd_acct_struct *acct) -{ - if (acct) { - struct pid_namespace *ns = acct->ns; - do_acct_process(acct); - INIT_WORK(&acct->work, close_work); - init_completion(&acct->done); - schedule_work(&acct->work); - wait_for_completion(&acct->done); - pin_remove(&acct->pin); - cmpxchg(&ns->bacct, acct, NULL); - acct->ns = NULL; - atomic_long_dec(&acct->count); - mutex_unlock(&acct->lock); - acct_put(acct); - } -} - -static void acct_pin_kill(struct fs_pin *pin) -{ - struct bsd_acct_struct *acct; - acct = container_of(pin, struct bsd_acct_struct, pin); - if (!atomic_long_inc_not_zero(&acct->count)) { - rcu_read_unlock(); - cpu_relax(); - return; - } - rcu_read_unlock(); - mutex_lock(&acct->lock); - if (!acct->ns) { - mutex_unlock(&acct->lock); - acct_put(acct); - acct = NULL; - } - acct_kill(acct); -} - static int acct_on(struct filename *pathname) { struct file *file; struct vfsmount *mnt, *internal; struct pid_namespace *ns = task_active_pid_ns(current); - struct bsd_acct_struct *acct, *old; + struct bsd_acct_struct *acct; + struct fs_pin *old; int err; acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL); @@ -252,18 +235,20 @@ static int acct_on(struct filename *pathname) file->f_path.mnt = internal; atomic_long_set(&acct->count, 1); - acct->pin.kill = acct_pin_kill; + init_fs_pin(&acct->pin, acct_pin_kill); acct->file = file; acct->needcheck = jiffies; acct->ns = ns; mutex_init(&acct->lock); + INIT_WORK(&acct->work, close_work); + init_completion(&acct->done); mutex_lock_nested(&acct->lock, 1); /* nobody has seen it yet */ pin_insert(&acct->pin, mnt); - old = acct_get(ns); - ns->bacct = acct; - acct_kill(old); + rcu_read_lock(); + old = xchg(&ns->bacct, &acct->pin); mutex_unlock(&acct->lock); + pin_kill(old); mnt_drop_write(mnt); mntput(mnt); return 0; @@ -299,7 +284,8 @@ SYSCALL_DEFINE1(acct, const char __user *, name) mutex_unlock(&acct_on_mutex); putname(tmp); } else { - acct_kill(acct_get(task_active_pid_ns(current))); + rcu_read_lock(); + pin_kill(task_active_pid_ns(current)->bacct); } return error; @@ -307,7 +293,8 @@ SYSCALL_DEFINE1(acct, const char __user *, name) void acct_exit_ns(struct pid_namespace *ns) { - acct_kill(acct_get(ns)); + rcu_read_lock(); + pin_kill(ns->bacct); } /* |