Re: [PATCH V2 1/3] dcache: add a new enum type for 'dentry_d_lock_class'

["yukuai (C)" <yukuai3@huawei.com>]

On 2019/11/30 11:43, Matthew Wilcox wrote:
> On Sat, Nov 30, 2019 at 10:02:23AM +0800, yu kuai wrote:
>> However, a single 'DENTRY_D_LOCK_NESTED' may not be enough if more than
>> two dentry are involed. So, add in 'DENTRY_D_LOCK_NESTED_TWICE'.
> 
> No.  These need meaningful names.  Indeed, I think D_LOCK_NESTED is
> a terrible name.
> 
> Looking at the calls:
> 
> $ git grep -n nested.*d_lock fs
> fs/autofs/expire.c:82:          spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
> fs/dcache.c:619:                spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
> fs/dcache.c:1086:       spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
> fs/dcache.c:1303:               spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
> fs/dcache.c:2822:               spin_lock_nested(&old_parent->d_lock, DENTRY_D_LOCK_NESTED);
> fs/dcache.c:2827:                       spin_lock_nested(&target->d_parent->d_lock,
> fs/dcache.c:2830:       spin_lock_nested(&dentry->d_lock, 2);
> fs/dcache.c:2831:       spin_lock_nested(&target->d_lock, 3);
> fs/dcache.c:3121:       spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
> fs/libfs.c:112:                 spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
> fs/libfs.c:341:         spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
> fs/notify/fsnotify.c:129:                       spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
> 
> Most of these would be well-expressed by DENTRY_D_LOCK_CHILD.
> 
> The exception is __d_move() where I think we should actually name the
> different lock classes instead of using a bare '2' and '3'.  Something
> like this, perhaps:
> 
Thanks for looking into this, do you mind if I replace your patch with 
the first two patches in the patchset?

Yu Kuai