From: Christoph Hellwig <hch@infradead.org>
To: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: linux-nfs@vger.kernel.org
Subject: Re: [PATCH 10/12] NFS: Do not serialise O_DIRECT reads and writes
Date: Wed, 15 Jun 2016 00:13:43 -0700 [thread overview]
Message-ID: <20160615071343.GC4318@infradead.org> (raw)
In-Reply-To: <1465931115-30784-10-git-send-email-trond.myklebust@primarydata.com>
> +void
> +nfs_lock_bio(struct nfs_inode *nfsi)
bio stands for buffered I/O? This could really use a more descriptive
name and/or a comment..
> +{
> + /* Be an optimist! */
> + down_read(&nfsi->io_lock);
> + if (test_bit(NFS_INO_ODIRECT, &nfsi->flags) == 0)
> + return;
> + up_read(&nfsi->io_lock);
So if no direct I/O is going on this locks shared?
> + /* Slow path.... */
> + down_write(&nfsi->io_lock);
> + clear_bit(NFS_INO_ODIRECT, &nfsi->flags);
> + downgrade_write(&nfsi->io_lock);
The whole locking here seems rather confusing. Why not use the XFS
locking model:
buffered write: exclusive
buffered read: shared
direct write: shared (exclusive for pagecache invalidate)
direct read: shared (exclusive for pagecache invalidate)
The nice thing is than in 4.7-rc i_mutex has been replaced with a
rw_mutex so you can just use that in shared mode for direct I/O
as-is without needing any new lock.
next prev parent reply other threads:[~2016-06-15 7:13 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-14 19:05 [PATCH 01/12] NFS: Don't flush caches for a getattr that races with writeback Trond Myklebust
2016-06-14 19:05 ` [PATCH 02/12] NFS: Cache access checks more aggressively Trond Myklebust
2016-06-14 19:05 ` [PATCH 03/12] NFS: Cache aggressively when file is open for writing Trond Myklebust
2016-06-14 19:05 ` [PATCH 04/12] NFS: Kill NFS_INO_NFS_INO_FLUSHING: it is a performance killer Trond Myklebust
2016-06-14 19:05 ` [PATCH 05/12] NFS: writepage of a single page should not be synchronous Trond Myklebust
2016-06-14 19:05 ` [PATCH 06/12] NFS: Don't hold the inode lock across fsync() Trond Myklebust
2016-06-14 19:05 ` [PATCH 07/12] NFS: Don't enable deep stack recursion when doing memory reclaim Trond Myklebust
2016-06-14 19:05 ` [PATCH 08/12] NFS: Fix O_DIRECT verifier problems Trond Myklebust
2016-06-14 19:05 ` [PATCH 09/12] NFS: Ensure we reset the write verifier 'committed' value on resend Trond Myklebust
2016-06-14 19:05 ` [PATCH 10/12] NFS: Do not serialise O_DIRECT reads and writes Trond Myklebust
2016-06-14 19:05 ` [PATCH 11/12] NFS: Don't count O_DIRECT reads in the inode->i_dio_count Trond Myklebust
2016-06-14 19:05 ` [PATCH 12/12] NFS: Clean up nfs_direct_complete() Trond Myklebust
2016-06-15 7:16 ` [PATCH 11/12] NFS: Don't count O_DIRECT reads in the inode->i_dio_count Christoph Hellwig
2016-06-15 14:36 ` Trond Myklebust
2016-06-15 14:41 ` Christoph Hellwig
2016-06-15 14:50 ` Trond Myklebust
2016-06-15 14:53 ` Christoph Hellwig
2016-06-15 7:13 ` Christoph Hellwig [this message]
2016-06-15 14:29 ` [PATCH 10/12] NFS: Do not serialise O_DIRECT reads and writes Trond Myklebust
2016-06-15 14:48 ` Christoph Hellwig
2016-06-15 14:52 ` Trond Myklebust
2016-06-15 14:56 ` Christoph Hellwig
2016-06-15 15:09 ` Trond Myklebust
2016-06-15 15:14 ` Christoph Hellwig
2016-06-15 15:45 ` Trond Myklebust
2016-06-16 9:12 ` Christoph Hellwig
2016-06-15 7:09 ` [PATCH 07/12] NFS: Don't enable deep stack recursion when doing memory reclaim Christoph Hellwig
2016-06-15 7:08 ` [PATCH 06/12] NFS: Don't hold the inode lock across fsync() Christoph Hellwig
2016-06-15 14:47 ` Trond Myklebust
2016-06-15 14:54 ` Christoph Hellwig
2016-06-17 1:11 ` [PATCH 03/12] NFS: Cache aggressively when file is open for writing Oleg Drokin
2016-06-17 14:01 ` Trond Myklebust
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