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    SubjectRe: [patch 05/27] fs: brlock vfsmount_lock
    On Sat, Apr 25, 2009 at 11:20:25AM +1000, npiggin@suse.de wrote:

    [overall: sane idea, but...]

    > +void vfsmount_read_lock(void)
    > +{
    > + spinlock_t *lock;
    > +
    > + lock = &get_cpu_var(vfsmount_lock);
    > + spin_lock(lock);
    > +}
    > +
    > +void vfsmount_read_unlock(void)
    > +{
    > + spinlock_t *lock;
    > +
    > + lock = &__get_cpu_var(vfsmount_lock);
    > + spin_unlock(lock);
    > + put_cpu_var(vfsmount_lock);
    > +}

    These might be hot enough to be worth inlining, at least in fs/namei.c
    users. Or not - really needs testing.

    > @@ -68,9 +113,9 @@ static int mnt_alloc_id(struct vfsmount
    >
    > retry:
    > ida_pre_get(&mnt_id_ida, GFP_KERNEL);
    > - spin_lock(&vfsmount_lock);
    > + vfsmount_write_lock();
    > res = ida_get_new(&mnt_id_ida, &mnt->mnt_id);
    > - spin_unlock(&vfsmount_lock);
    > + vfsmount_write_unlock();

    Yuck. _Really_ an overkill here.

    > static void mnt_free_id(struct vfsmount *mnt)
    > {
    > - spin_lock(&vfsmount_lock);
    > + vfsmount_write_lock();
    > ida_remove(&mnt_id_ida, mnt->mnt_id);
    > - spin_unlock(&vfsmount_lock);
    > + vfsmount_write_unlock();
    > }

    Ditto.

    Missing: description of when we need it for read/when we need it for write.


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      Last update: 2009-04-25 05:53    [W:0.034 / U:0.632 seconds]
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