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From: John Ogness <>
To: Al Viro <>,
	Sebastian Andrzej Siewior <>
	Thomas Gleixner <>,
	Peter Zijlstra <>
Subject: Re: [RFC PATCH v2] fs/namespace: use percpu_rw_semaphore for writer holding
Date: Mon, 20 Jul 2020 17:41:01 +0206	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 2020-07-19, Al Viro <> wrote:
>> The MNT_WRITE_HOLD flag is used to manually implement a rwsem.
> Could you show me where does it currently sleep?  Your version does,
> unless I'm misreading it...

You are reading it correctly. This patch introduces new possible
sleeping for__mnt_want_write() when writers for a superblock are being

The RFCv1 [0] is a variant that does not introduce sleeping, but instead
reverts back to per-cpu spinlocks.

Sebastian and I are requesting comments on these two possible
solutions. Or perhaps you have an idea how to solve the potential live
lock situation.

John Ogness


      reply	other threads:[~2020-07-20 15:35 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-02 15:46 Sebastian Andrzej Siewior
2020-07-19  1:49 ` Al Viro
2020-07-20 15:35   ` John Ogness [this message]

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