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From: Christoph Hellwig <hch@lst.de>
To: John Garry <john.g.garry@oracle.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>, Chris Mason <clm@fb.com>,
	Josef Bacik <josef@toxicpanda.com>,
	brauner@kernel.org, djwong@kernel.org, hch@lst.de,
	viro@zeniv.linux.org.uk, jack@suse.cz, cem@kernel.org,
	linux-fsdevel@vger.kernel.org, dchinner@redhat.com,
	linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org,
	ojaswin@linux.ibm.com, ritesh.list@gmail.com,
	martin.petersen@oracle.com, linux-ext4@vger.kernel.org,
	linux-block@vger.kernel.org, catherine.hoang@oracle.com,
	linux-api@vger.kernel.org, Pankaj Raghav <p.raghav@samsung.com>,
	Daniel Gomez <da.gomez@samsung.com>
Subject: Re: [PATCH v7 11/14] xfs: add xfs_file_dio_write_atomic()
Date: Wed, 23 Apr 2025 07:44:20 +0200	[thread overview]
Message-ID: <20250423054420.GB23087@lst.de> (raw)
In-Reply-To: <69302bf1-78b4-4b95-8e9b-df56dd1091c0@oracle.com>

On Tue, Apr 22, 2025 at 07:08:32AM +0100, John Garry wrote:
> So consider userspace wants to write something atomically and we fail as a 
> HW-based atomic write is not possible. What is userspace going to do next?

Exactly.

>
> I heard something like "if HW-based atomics are not possible, then 
> something has not been configured properly for the FS" - that something 
> would be extent granularity and alignment, but we don't have a method to 
> ensure this. That is the whole point of having a FS fallback.

We now have the opt limit, right? (I'll review the reposted series
ASAP, but for now I'll assume it)  They can just tune their applications
to it, and trigger on a trace point for the fallback to monitor it.


  parent reply	other threads:[~2025-04-23  5:44 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-15 12:14 [PATCH v7 00/14] large atomic writes for xfs John Garry
2025-04-15 12:14 ` [PATCH v7 01/14] fs: add atomic write unit max opt to statx John Garry
2025-04-15 12:14 ` [PATCH v7 02/14] xfs: add helpers to compute log item overhead John Garry
2025-04-15 12:14 ` [PATCH v7 03/14] xfs: add helpers to compute transaction reservation for finishing intent items John Garry
2025-04-15 12:14 ` [PATCH v7 04/14] xfs: rename xfs_inode_can_atomicwrite() -> xfs_inode_can_hw_atomicwrite() John Garry
2025-04-15 12:14 ` [PATCH v7 05/14] xfs: allow block allocator to take an alignment hint John Garry
2025-04-15 12:14 ` [PATCH v7 06/14] xfs: refactor xfs_reflink_end_cow_extent() John Garry
2025-04-15 12:14 ` [PATCH v7 07/14] xfs: refine atomic write size check in xfs_file_write_iter() John Garry
2025-04-15 12:14 ` [PATCH v7 08/14] xfs: add xfs_atomic_write_cow_iomap_begin() John Garry
2025-04-15 12:14 ` [PATCH v7 09/14] xfs: add large atomic writes checks in xfs_direct_write_iomap_begin() John Garry
2025-04-15 17:34   ` Darrick J. Wong
2025-04-15 17:46     ` John Garry
2025-04-15 12:14 ` [PATCH v7 10/14] xfs: commit CoW-based atomic writes atomically John Garry
2025-04-15 12:14 ` [PATCH v7 11/14] xfs: add xfs_file_dio_write_atomic() John Garry
2025-04-21  4:00   ` Darrick J. Wong
2025-04-21  5:47     ` John Garry
2025-04-21 16:42       ` Darrick J. Wong
2025-04-23  5:42         ` Christoph Hellwig
2025-04-23  8:19           ` Christoph Hellwig
2025-04-23 14:51             ` Darrick J. Wong
2025-04-23 14:53           ` Darrick J. Wong
2025-04-21 21:18   ` Luis Chamberlain
2025-04-22  6:08     ` John Garry
2025-04-23  5:18       ` Luis Chamberlain
2025-04-23  7:08         ` John Garry
2025-04-23  7:36           ` Luis Chamberlain
2025-04-23  5:44       ` Christoph Hellwig [this message]
2025-04-23  7:02         ` John Garry
2025-04-15 12:14 ` [PATCH v7 12/14] xfs: add xfs_compute_atomic_write_unit_max() John Garry
2025-04-15 16:25   ` Darrick J. Wong
2025-04-15 16:35     ` John Garry
2025-04-15 16:39       ` Darrick J. Wong
2025-04-15 12:14 ` [PATCH v7 13/14] xfs: update atomic write limits John Garry
2025-04-15 16:26   ` Darrick J. Wong
2025-04-15 12:14 ` [PATCH v7 14/14] xfs: allow sysadmins to specify a maximum atomic write limit at mount time John Garry
2025-04-15 15:35   ` Randy Dunlap
2025-04-15 16:55   ` Darrick J. Wong
2025-04-15 22:36   ` [PATCH v7.1 " Darrick J. Wong
2025-04-16 10:08     ` John Garry
2025-04-16 16:26       ` Darrick J. Wong

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