diff options
| -rw-r--r-- | kernel/acct.c | 220 |
1 files changed, 114 insertions, 106 deletions
diff --git a/kernel/acct.c b/kernel/acct.c index 08963a2..f9ef9db 100644 --- a/kernel/acct.c +++ b/kernel/acct.c @@ -75,15 +75,11 @@ 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 pid_namespace *ns, struct file *); +static void do_acct_process(struct bsd_acct_struct *acct); -/* - * This structure is used so that all the data protected by lock - * can be placed in the same cache line as the lock. This primes - * the cache line to have the data after getting the lock. - */ struct bsd_acct_struct { + long count; + struct mutex lock; int active; unsigned long needcheck; struct file *file; @@ -157,39 +153,59 @@ out: return res; } -/* - * Close the old accounting file (if currently open) and then replace - * it with file (if non-NULL). - * - * NOTE: acct_lock MUST be held on entry and exit. - */ -static void acct_file_reopen(struct bsd_acct_struct *acct, struct file *file, - struct pid_namespace *ns) +static void acct_put(struct bsd_acct_struct *p) { - struct file *old_acct = NULL; - struct pid_namespace *old_ns = NULL; - - if (acct->file) { - old_acct = acct->file; - old_ns = acct->ns; - acct->active = 0; - acct->file = NULL; - acct->ns = NULL; - list_del(&acct->list); - } - if (file) { - acct->file = file; - acct->ns = ns; - acct->needcheck = jiffies; - acct->active = 0; - list_add(&acct->list, &acct_list); + spin_lock(&acct_lock); + if (!--p->count) + kfree(p); + spin_unlock(&acct_lock); +} + +static struct bsd_acct_struct *acct_get(struct bsd_acct_struct **p) +{ + struct bsd_acct_struct *res; + spin_lock(&acct_lock); +again: + res = *p; + if (res) + res->count++; + spin_unlock(&acct_lock); + if (res) { + mutex_lock(&res->lock); + if (!res->ns) { + mutex_unlock(&res->lock); + spin_lock(&acct_lock); + if (!--res->count) + kfree(res); + goto again; + } } - if (old_acct) { - mnt_unpin(old_acct->f_path.mnt); + return res; +} + +static void acct_kill(struct bsd_acct_struct *acct, + struct bsd_acct_struct *new) +{ + if (acct) { + struct file *file = acct->file; + struct pid_namespace *ns = acct->ns; + spin_lock(&acct_lock); + list_del(&acct->list); + mnt_unpin(file->f_path.mnt); spin_unlock(&acct_lock); - do_acct_process(acct, old_ns, old_acct); - filp_close(old_acct, NULL); + do_acct_process(acct); + filp_close(file, NULL); spin_lock(&acct_lock); + ns->bacct = new; + if (new) { + mnt_pin(new->file->f_path.mnt); + list_add(&new->list, &acct_list); + } + acct->ns = NULL; + mutex_unlock(&acct->lock); + if (!(acct->count -= 2)) + kfree(acct); + spin_unlock(&acct_lock); } } @@ -197,47 +213,50 @@ static int acct_on(struct filename *pathname) { struct file *file; struct vfsmount *mnt; - struct pid_namespace *ns; - struct bsd_acct_struct *acct = NULL; + struct pid_namespace *ns = task_active_pid_ns(current); + struct bsd_acct_struct *acct, *old; + + acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL); + if (!acct) + return -ENOMEM; /* Difference from BSD - they don't do O_APPEND */ file = file_open_name(pathname, O_WRONLY|O_APPEND|O_LARGEFILE, 0); - if (IS_ERR(file)) + if (IS_ERR(file)) { + kfree(acct); return PTR_ERR(file); + } if (!S_ISREG(file_inode(file)->i_mode)) { + kfree(acct); filp_close(file, NULL); return -EACCES; } if (!file->f_op->write) { + kfree(acct); filp_close(file, NULL); 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; - } - } + acct->count = 1; + acct->file = file; + acct->needcheck = jiffies; + acct->ns = ns; + mutex_init(&acct->lock); + mnt = file->f_path.mnt; - spin_lock(&acct_lock); - if (ns->bacct == NULL) { + old = acct_get(&ns->bacct); + if (old) { + acct_kill(old, acct); + } else { + spin_lock(&acct_lock); ns->bacct = acct; - acct = NULL; + mnt_pin(mnt); + list_add(&acct->list, &acct_list); + spin_unlock(&acct_lock); } - - mnt = file->f_path.mnt; - mnt_pin(mnt); - acct_file_reopen(ns->bacct, file, ns); - spin_unlock(&acct_lock); - mntput(mnt); /* it's pinned, now give up active reference */ - kfree(acct); - return 0; } @@ -270,15 +289,7 @@ SYSCALL_DEFINE1(acct, const char __user *, name) mutex_unlock(&acct_on_mutex); putname(tmp); } else { - struct bsd_acct_struct *acct; - - acct = task_active_pid_ns(current)->bacct; - if (acct == NULL) - return 0; - - spin_lock(&acct_lock); - acct_file_reopen(acct, NULL, NULL); - spin_unlock(&acct_lock); + acct_kill(acct_get(&task_active_pid_ns(current)->bacct), NULL); } return error; @@ -298,8 +309,19 @@ void acct_auto_close_mnt(struct vfsmount *m) spin_lock(&acct_lock); restart: list_for_each_entry(acct, &acct_list, list) - if (acct->file && acct->file->f_path.mnt == m) { - acct_file_reopen(acct, NULL, NULL); + if (acct->file->f_path.mnt == m) { + acct->count++; + spin_unlock(&acct_lock); + mutex_lock(&acct->lock); + if (!acct->ns) { + mutex_unlock(&acct->lock); + spin_lock(&acct_lock); + if (!--acct->count) + kfree(acct); + goto restart; + } + acct_kill(acct, NULL); + spin_lock(&acct_lock); goto restart; } spin_unlock(&acct_lock); @@ -319,8 +341,19 @@ void acct_auto_close(struct super_block *sb) spin_lock(&acct_lock); restart: list_for_each_entry(acct, &acct_list, list) - if (acct->file && acct->file->f_path.dentry->d_sb == sb) { - acct_file_reopen(acct, NULL, NULL); + if (acct->file->f_path.dentry->d_sb == sb) { + acct->count++; + spin_unlock(&acct_lock); + mutex_lock(&acct->lock); + if (!acct->ns) { + mutex_unlock(&acct->lock); + spin_lock(&acct_lock); + if (!--acct->count) + kfree(acct); + goto restart; + } + acct_kill(acct, NULL); + spin_lock(&acct_lock); goto restart; } spin_unlock(&acct_lock); @@ -328,17 +361,7 @@ restart: void acct_exit_ns(struct pid_namespace *ns) { - struct bsd_acct_struct *acct = ns->bacct; - - if (acct == NULL) - return; - - spin_lock(&acct_lock); - if (acct->file != NULL) - acct_file_reopen(acct, NULL, NULL); - spin_unlock(&acct_lock); - - kfree(acct); + acct_kill(acct_get(&ns->bacct), NULL); } /* @@ -507,12 +530,13 @@ static void fill_ac(acct_t *ac) /* * do_acct_process does all actual work. Caller holds the reference to file. */ -static void do_acct_process(struct bsd_acct_struct *acct, - struct pid_namespace *ns, struct file *file) +static void do_acct_process(struct bsd_acct_struct *acct) { acct_t ac; unsigned long flim; const struct cred *orig_cred; + struct pid_namespace *ns = acct->ns; + struct file *file = acct->file; /* * Accounting records are not subject to resource limits. @@ -606,27 +630,12 @@ void acct_collect(long exitcode, int group_dead) static void slow_acct_process(struct pid_namespace *ns) { for ( ; ns; ns = ns->parent) { - struct file *file = NULL; - struct bsd_acct_struct *acct; - - acct = ns->bacct; - /* - * accelerate the common fastpath: - */ - if (!acct || !acct->file) - continue; - - spin_lock(&acct_lock); - file = acct->file; - if (unlikely(!file)) { - spin_unlock(&acct_lock); - continue; + struct bsd_acct_struct *acct = acct_get(&ns->bacct); + if (acct) { + do_acct_process(acct); + mutex_unlock(&acct->lock); + acct_put(acct); } - get_file(file); - spin_unlock(&acct_lock); - - do_acct_process(acct, ns, file); - fput(file); } } @@ -645,8 +654,7 @@ void acct_process(void) * its parent. */ for (ns = task_active_pid_ns(current); ns != NULL; ns = ns->parent) { - struct bsd_acct_struct *acct = ns->bacct; - if (acct && acct->file) + if (ns->bacct) break; } if (unlikely(ns)) |
