bsdacct: turn the acct_lock from on-the-struct to global

Don't use per-bsd-acct-struct lock, but work with a global one.

This lock is taken for short periods, so it doesn't seem it'll become a
bottleneck, but it will allow us to easily avoid many locking difficulties
in the future.

So this is a mostly s/acct_globals.lock/acct_lock/ over the file.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/acct.c b/kernel/acct.c
index 05f8bc0..fc71c13 100644 (file)
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -83,7 +83,6 @@ static void do_acct_process(struct pid_namespace *ns, struct file *);
  * the cache line to have the data after getting the lock.
  */
 struct bsd_acct_struct {
-       spinlock_t              lock;
        volatile int            active;
        volatile int            needcheck;
        struct file             *file;
@@ -91,8 +90,9 @@ struct bsd_acct_struct {
        struct timer_list       timer;
 };
 
-static struct bsd_acct_struct acct_globals __cacheline_aligned =
-       {__SPIN_LOCK_UNLOCKED(acct_globals.lock)};
+static DEFINE_SPINLOCK(acct_lock);
+
+static struct bsd_acct_struct acct_globals __cacheline_aligned;
 
 /*
  * Called whenever the timer says to check the free space.
@@ -114,11 +114,11 @@ static int check_free_space(struct file *file)
        sector_t resume;
        sector_t suspend;
 
-       spin_lock(&acct_globals.lock);
+       spin_lock(&acct_lock);
        res = acct_globals.active;
        if (!file || !acct_globals.needcheck)
                goto out;
-       spin_unlock(&acct_globals.lock);
+       spin_unlock(&acct_lock);
 
        /* May block */
        if (vfs_statfs(file->f_path.dentry, &sbuf))
@@ -140,7 +140,7 @@ static int check_free_space(struct file *file)
         * If some joker switched acct_globals.file under us we'ld better be
         * silent and _not_ touch anything.
         */
-       spin_lock(&acct_globals.lock);
+       spin_lock(&acct_lock);
        if (file != acct_globals.file) {
                if (act)
                        res = act>0;
@@ -165,7 +165,7 @@ static int check_free_space(struct file *file)
        add_timer(&acct_globals.timer);
        res = acct_globals.active;
 out:
-       spin_unlock(&acct_globals.lock);
+       spin_unlock(&acct_lock);
        return res;
 }
 
@@ -173,7 +173,7 @@ out:
  * Close the old accounting file (if currently open) and then replace
  * it with file (if non-NULL).
  *
- * NOTE: acct_globals.lock MUST be held on entry and exit.
+ * NOTE: acct_lock MUST be held on entry and exit.
  */
 static void acct_file_reopen(struct file *file)
 {
@@ -201,11 +201,11 @@ static void acct_file_reopen(struct file *file)
        }
        if (old_acct) {
                mnt_unpin(old_acct->f_path.mnt);
-               spin_unlock(&acct_globals.lock);
+               spin_unlock(&acct_lock);
                do_acct_process(old_ns, old_acct);
                filp_close(old_acct, NULL);
                put_pid_ns(old_ns);
-               spin_lock(&acct_globals.lock);
+               spin_lock(&acct_lock);
        }
 }
 
@@ -235,10 +235,10 @@ static int acct_on(char *name)
                return error;
        }
 
-       spin_lock(&acct_globals.lock);
+       spin_lock(&acct_lock);
        mnt_pin(file->f_path.mnt);
        acct_file_reopen(file);
-       spin_unlock(&acct_globals.lock);
+       spin_unlock(&acct_lock);
 
        mntput(file->f_path.mnt); /* it's pinned, now give up active reference */
 
@@ -272,9 +272,9 @@ asmlinkage long sys_acct(const char __user *name)
        } else {
                error = security_acct(NULL);
                if (!error) {
-                       spin_lock(&acct_globals.lock);
+                       spin_lock(&acct_lock);
                        acct_file_reopen(NULL);
-                       spin_unlock(&acct_globals.lock);
+                       spin_unlock(&acct_lock);
                }
        }
        return error;
@@ -289,10 +289,10 @@ asmlinkage long sys_acct(const char __user *name)
  */
 void acct_auto_close_mnt(struct vfsmount *m)
 {
-       spin_lock(&acct_globals.lock);
+       spin_lock(&acct_lock);
        if (acct_globals.file && acct_globals.file->f_path.mnt == m)
                acct_file_reopen(NULL);
-       spin_unlock(&acct_globals.lock);
+       spin_unlock(&acct_lock);
 }
 
 /**
@@ -304,12 +304,12 @@ void acct_auto_close_mnt(struct vfsmount *m)
  */
 void acct_auto_close(struct super_block *sb)
 {
-       spin_lock(&acct_globals.lock);
+       spin_lock(&acct_lock);
        if (acct_globals.file &&
            acct_globals.file->f_path.mnt->mnt_sb == sb) {
                acct_file_reopen(NULL);
        }
-       spin_unlock(&acct_globals.lock);
+       spin_unlock(&acct_lock);
 }
 
 /*
@@ -594,15 +594,15 @@ void acct_process(void)
        if (!acct_globals.file)
                return;
 
-       spin_lock(&acct_globals.lock);
+       spin_lock(&acct_lock);
        file = acct_globals.file;
        if (unlikely(!file)) {
-               spin_unlock(&acct_globals.lock);
+               spin_unlock(&acct_lock);
                return;
        }
        get_file(file);
        ns = get_pid_ns(acct_globals.ns);
-       spin_unlock(&acct_globals.lock);
+       spin_unlock(&acct_lock);
 
        do_acct_process(ns, file);
        fput(file);