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In-Reply-To: <20190921140731.GQ1131@ZenIV.linux.org.uk>
From:   Amir Goldstein <amir73il@gmail.com>
Date:   Wed, 25 Sep 2019 14:59:47 +0300
Message-ID: <CAOQ4uxh-FH7JZP9fVqHXYJkbLA+NK6fX7HQex-XwY0Sha-R_kw@mail.gmail.com>
Subject: Re: [PATCH] Re: Possible FS race condition between iterate_dir and d_alloc_parallel
To:     Al Viro <viro@zeniv.linux.org.uk>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        "zhengbin (A)" <zhengbin13@huawei.com>, Jan Kara <jack@suse.cz>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        "zhangyi (F)" <yi.zhang@huawei.com>, renxudong1@huawei.com,
        Hou Tao <houtao1@huawei.com>
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On Mon, Sep 23, 2019 at 5:34 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> FWIW, #next.dcache has the straight conversion to hlist.

Note that this:
@@ -108,8 +108,8 @@ struct dentry {
                struct list_head d_lru;         /* LRU list */
                wait_queue_head_t *d_wait;      /* in-lookup ones only */
        };
-       struct list_head d_child;       /* child of parent list */
-       struct list_head d_subdirs;     /* our children */
+       struct hlist_node d_sibling;    /* child of parent list */
+       struct hlist_head d_children;   /* our children */

Changes the 'standard' struct dentry size from 192 to 184.

Does that matter for cache line alignment?

Should struct dentry be ____cacheline_aligned?

Thanks,
Amir.