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From: Greg KH <gregkh@linuxfoundation.org>
To: Shaohua Li <shli@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
	tj@kernel.org, hch@lst.de, axboe@fb.com, rostedt@goodmis.org,
	lizefan@huawei.com, Kernel-team@fb.com, Shaohua Li <shli@fb.com>
Subject: Re: [PATCH V4 02/12] kernfs: implement i_generation
Date: Thu, 29 Jun 2017 14:51:41 +0200	[thread overview]
Message-ID: <20170629125141.GG26046@kroah.com> (raw)
In-Reply-To: <327539f91326b971b9071d518a32435f41013550.1498666964.git.shli@fb.com>

On Wed, Jun 28, 2017 at 09:29:52AM -0700, Shaohua Li wrote:
> From: Shaohua Li <shli@fb.com>
> 
> Set i_generation for kernfs inode. This is required to implement
> exportfs operations. The generation is 32-bit, so it's possible the
> generation wraps up and we find stale files. To reduce the posssibility,
> we don't reuse inode numer immediately. When the inode number allocation
> wraps, we increase generation number. In this way generation/inode
> number consist of a 64-bit number which is unlikely duplicated. This
> does make the idr tree more sparse and waste some memory. Since idr
> manages 32-bit keys, idr uses a 6-level radix tree, each level covers 6
> bits of the key. In a 100k inode kernfs, the worst case will have around
> 300k radix tree node. Each node is 576bytes, so the tree will use about
> ~150M memory. Sounds not too bad, if this really is a problem, we should
> find better data structure.
> 
> Acked-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Shaohua Li <shli@fb.com>

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

  reply	other threads:[~2017-06-29 12:51 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-28 16:29 [PATCH V4 00/12] blktrace: output cgroup info Shaohua Li
2017-06-28 16:29 ` [PATCH V4 01/12] kernfs: use idr instead of ida to manage inode number Shaohua Li
2017-06-29 12:51   ` Greg KH
2017-06-28 16:29 ` [PATCH V4 02/12] kernfs: implement i_generation Shaohua Li
2017-06-29 12:51   ` Greg KH [this message]
2017-06-28 16:29 ` [PATCH V4 03/12] kernfs: add an API to get kernfs node from inode number Shaohua Li
2017-06-28 18:07   ` Tejun Heo
2017-06-29 12:50   ` Greg KH
2017-06-28 16:29 ` [PATCH V4 04/12] kernfs: don't set dentry->d_fsdata Shaohua Li
2017-06-29 12:51   ` Greg KH
2017-06-28 16:29 ` [PATCH V4 05/12] kernfs: introduce kernfs_node_id Shaohua Li
2017-06-29 12:51   ` Greg KH
2017-06-28 16:29 ` [PATCH V4 06/12] kernfs: add exportfs operations Shaohua Li
2017-06-29 12:50   ` Greg KH
2017-06-28 16:29 ` [PATCH V4 07/12] cgroup: export fhandle info for a cgroup Shaohua Li
2017-06-28 18:12   ` Tejun Heo
2017-06-28 16:29 ` [PATCH V4 08/12] blktrace: export cgroup info in trace Shaohua Li
2017-06-28 16:56   ` Steven Rostedt
2017-06-28 16:29 ` [PATCH V4 09/12] block: always attach cgroup info into bio Shaohua Li
2017-06-28 16:30 ` [PATCH V4 10/12] block: call __bio_free in bio_endio Shaohua Li
2017-06-28 21:29   ` Christoph Hellwig
2017-06-28 21:42     ` Shaohua Li
2017-06-29 17:15       ` Christoph Hellwig
2017-06-29 18:35         ` Shaohua Li
2017-06-29 20:22           ` Christoph Hellwig
2017-06-28 16:30 ` [PATCH V4 11/12] blktrace: add an option to allow displying cgroup path Shaohua Li
2017-06-28 16:41   ` Jens Axboe
2017-06-28 16:30 ` [PATCH V4 12/12] block: use standard blktrace API to output cgroup info for debug notes Shaohua Li
2017-06-28 16:43 ` [PATCH V4 00/12] blktrace: output cgroup info Jens Axboe
2017-06-28 16:53   ` Shaohua Li
2017-06-28 16:54     ` Jens Axboe
2017-06-28 18:11       ` Tejun Heo
2017-06-28 20:57         ` Jens Axboe
2017-06-28 21:25           ` Tejun Heo
2017-06-29 12:50             ` Greg KH
2017-06-29 18:39           ` Shaohua Li

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