From: Christoph Hellwig <hch@infradead.org>
To: Trond Myklebust <trondmy@primarydata.com>
Cc: Christoph Hellwig <hch@infradead.org>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v2 11/12] NFS: Remove inode->i_dio_count from the NFS O_DIRECT code
Date: Thu, 23 Jun 2016 03:19:56 -0700 [thread overview]
Message-ID: <20160623101956.GA2744@infradead.org> (raw)
In-Reply-To: <07829F3C-FCAA-42C0-8AFA-173370A55BDE@primarydata.com>
On Wed, Jun 22, 2016 at 04:58:05PM +0000, Trond Myklebust wrote:
> > For the AIO case that's not true, we can't hold i_rwsem until
> > aio completes. So for something that does block allocations we'll
> > need something like i_dio_count still. This probably includes the
> > block / scsi layout code.
>
> Why can?t we hold the i_rwsem until aio completes?
Because Linux rw_semaphores require have owner semantics, and require
the owner that acquired them to release them again. If we have
an AIO request we're not going to complete the request in the calling
context, though.
The same is true for regular mutexes, that's why we drop the inode lock
at the end of nfs_file_direct_read/write even if I/O might still be
pending.
next prev parent reply other threads:[~2016-06-23 10:19 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-21 21:34 [PATCH v2 01/12] NFS: Don't flush caches for a getattr that races with writeback Trond Myklebust
2016-06-21 21:34 ` [PATCH v2 02/12] NFS: Cache access checks more aggressively Trond Myklebust
2016-06-21 21:34 ` [PATCH v2 03/12] NFS: Cache aggressively when file is open for writing Trond Myklebust
2016-06-21 21:34 ` [PATCH v2 04/12] NFS: Kill NFS_INO_NFS_INO_FLUSHING: it is a performance killer Trond Myklebust
2016-06-21 21:34 ` [PATCH v2 05/12] NFS: writepage of a single page should not be synchronous Trond Myklebust
2016-06-21 21:34 ` [PATCH v2 06/12] NFS: Don't hold the inode lock across fsync() Trond Myklebust
2016-06-21 21:34 ` [PATCH v2 07/12] NFS: Don't call COMMIT in ->releasepage() Trond Myklebust
2016-06-21 21:34 ` [PATCH v2 08/12] NFS: Fix O_DIRECT verifier problems Trond Myklebust
2016-06-21 21:34 ` [PATCH v2 09/12] NFS: Ensure we reset the write verifier 'committed' value on resend Trond Myklebust
2016-06-21 21:34 ` [PATCH v2 10/12] NFS: Do not serialise O_DIRECT reads and writes Trond Myklebust
2016-06-21 21:34 ` [PATCH v2 11/12] NFS: Remove inode->i_dio_count from the NFS O_DIRECT code Trond Myklebust
2016-06-21 21:34 ` [PATCH v2 12/12] NFS: Clean up nfs_direct_complete() Trond Myklebust
2016-06-22 16:43 ` Christoph Hellwig
2016-06-22 16:42 ` [PATCH v2 11/12] NFS: Remove inode->i_dio_count from the NFS O_DIRECT code Christoph Hellwig
2016-06-22 16:58 ` Trond Myklebust
2016-06-23 10:19 ` Christoph Hellwig [this message]
2016-06-22 17:58 ` Anna Schumaker
2016-06-22 18:06 ` Trond Myklebust
2016-06-22 18:08 ` Anna Schumaker
2016-06-22 18:51 ` Anna Schumaker
2016-06-22 19:42 ` Trond Myklebust
2016-06-22 16:47 ` [PATCH v2 10/12] NFS: Do not serialise O_DIRECT reads and writes Christoph Hellwig
2016-06-22 17:24 ` Trond Myklebust
2016-06-23 11:00 ` Christoph Hellwig
2016-06-21 22:25 ` [PATCH v2 03/12] NFS: Cache aggressively when file is open for writing Oleg Drokin
2016-06-22 13:06 ` Trond Myklebust
2016-06-22 16:19 ` Oleg Drokin
2016-06-22 15:48 ` [PATCH v2 01/12] NFS: Don't flush caches for a getattr that races with writeback Christoph Hellwig
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