From: Christoph Hellwig <hch@lst.de>
To: John Garry <john.g.garry@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
Chandan Babu R <chandan.babu@oracle.com>,
"Darrick J. Wong" <djwong@kernel.org>,
Hongbo Li <lihongbo22@huawei.com>,
Ryusuke Konishi <konishi.ryusuke@gmail.com>,
linux-nilfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-xfs@vger.kernel.org
Subject: Re: [PATCH 4/4] xfs: report the correct read/write dio alignment for reflinked inodes
Date: Tue, 7 Jan 2025 07:10:12 +0100 [thread overview]
Message-ID: <20250107061012.GA13898@lst.de> (raw)
In-Reply-To: <dd525ca1-68ff-4f6d-87a9-b0c67e592f83@oracle.com>
On Mon, Jan 06, 2025 at 06:37:06PM +0000, John Garry wrote:
>> + /*
>> + * On COW inodes we are forced to always rewrite an entire file system
>> + * block or RT extent.
>> + *
>> + * Because applications assume they can do sector sized direct writes
>> + * on XFS we fall back to buffered I/O for sub-block direct I/O in that
>> + * case. Because that needs to copy the entire block into the buffer
>> + * cache it is highly inefficient and can easily lead to page cache
>> + * invalidation races.
>> + *
>> + * Tell applications to avoid this case by reporting the natively
>> + * supported direct I/O read alignment.
>
> Maybe I mis-read the complete comment, but did you really mean "natively
> supported direct I/O write alignment"? You have been talking about writes
> only, but then finally mention read alignment.
No, this is indeed intended to talk about the different (smaller) read
alignment we are now reporting. But I guess the wording is confusing
enough that I should improve it?
next prev parent reply other threads:[~2025-01-07 6:10 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-06 15:15 add STATX_DIO_READ_ALIGN Christoph Hellwig
2025-01-06 15:15 ` [PATCH 1/4] fs: reformat the statx definition Christoph Hellwig
2025-01-06 16:28 ` Jan Kara
2025-01-06 15:15 ` [PATCH 2/4] fs: add STATX_DIO_READ_ALIGN Christoph Hellwig
2025-01-06 16:32 ` Jan Kara
2025-01-06 16:40 ` Christoph Hellwig
2025-01-06 15:15 ` [PATCH 3/4] xfs: cleanup xfs_vn_getattr Christoph Hellwig
2025-01-06 17:07 ` John Garry
2025-01-06 15:15 ` [PATCH 4/4] xfs: report the correct read/write dio alignment for reflinked inodes Christoph Hellwig
2025-01-06 17:33 ` Darrick J. Wong
2025-01-06 18:37 ` John Garry
2025-01-07 6:10 ` Christoph Hellwig [this message]
2025-01-07 7:03 ` Darrick J. Wong
2025-01-07 9:00 ` John Garry
2025-01-06 15:19 ` [PATCH] statx.2: document STATX_DIO_READ_ALIGN Christoph Hellwig
2025-01-06 17:40 ` Darrick J. Wong
2025-01-06 18:09 ` Christoph Hellwig
2025-01-06 19:09 ` Darrick J. Wong
2025-01-06 22:01 ` Alejandro Colomar
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