Re: [PATCH/RFC] VFS: don't keep disconnected dentries on d_anon

From: NeilBrown
Date: Wed Dec 20 2017 - 18:13:56 EST

On Wed, Dec 20 2017, Matthew Wilcox wrote:

> On Thu, Dec 21, 2017 at 09:45:40AM +1100, NeilBrown wrote:
>> -c/ Helper routines to allocate anonymous dentries, and to help attach
>> + prefix. If the refcount on a dentry with this flag set
>> + becomes zero, the dentry is immediately discarded, rather than being
>> + kept in the dcache. If a dentry that is not already in the dcache
>> + is repeatedly accessed by filehandle (as NFSD might do), an new dentry
>> + will be a allocated for each access, and discarded at the end of
> s/a //
>> + the access. As there is no parent, children, or name in the dentry
>> + is it unlikely that there will be any useful information to lose,
>> + and allocating a new dentry should normally be fast.
> How about:
> As the dentry is completely unattached, there is little information to
> lose, and allocating a new dentry is normally fast.

Yes, that is less verbose, and probably just as informative.
Every time I rehearse this argument I wonder about d_fsdata.
I don't think it is actually relevant, but I feel that by not mentioning
it, I'm being dishonest... Maybe I should think of it as being "less

Thanks - if this gets far enough to deserve a resent, I'll add those


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