From: John Garry <john.g.garry@oracle.com>
To: Dave Chinner <david@fromorbit.com>
Cc: djwong@kernel.org, hch@lst.de, viro@zeniv.linux.org.uk,
brauner@kernel.org, jack@suse.cz, chandan.babu@oracle.com,
axboe@kernel.dk, martin.petersen@oracle.com,
linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org, tytso@mit.edu, jbongio@google.com,
ojaswin@linux.ibm.com, ritesh.list@gmail.com,
linux-block@vger.kernel.org
Subject: Re: [PATCH v2 12/14] fs: xfs: Support atomic write for statx
Date: Thu, 7 Mar 2024 10:35:16 +0000 [thread overview]
Message-ID: <6430d813-cb30-4a66-94e1-ea89bdc921da@oracle.com> (raw)
In-Reply-To: <ZejgovFe/pWCQ4uM@dread.disaster.area>
On 06/03/2024 21:31, Dave Chinner wrote:
>> + xfs_extlen_t extsz = xfs_get_extsz(ip);
>> + struct xfs_buftarg *target = xfs_inode_buftarg(ip);
>> + struct block_device *bdev = target->bt_bdev;
>> + struct request_queue *q = bdev->bd_queue;
>> + struct xfs_mount *mp = ip->i_mount;
>> + struct xfs_sb *sbp = &mp->m_sb;
>> + unsigned int awu_min, awu_max;
>> + unsigned int extsz_bytes = XFS_FSB_TO_B(mp, extsz);
>> +
>> + awu_min = queue_atomic_write_unit_min_bytes(q);
>> + awu_max = queue_atomic_write_unit_max_bytes(q);
> We really should be storing these in the xfs_buftarg at mount time,
> like we do logical and physical sector sizes.
This has been mentioned previously, and Darrick thought that it was not
safe. Please see first response in:
https://lore.kernel.org/linux-xfs/20231003161029.GG21298@frogsfrogsfrogs/#t
So if this really is true, then I'll stick with something like what I
have here and add a comment on that.
However, in this series the block layer does check for out-of-range
atomic write BIOs in 1/14. So we could store the values in xfs_buftarg,
as you suggest for the lookup here. If the bdev geometry does really
change beneath us, worse thing that happens is that we may report
incorrect values for statx.
> Similar to sector
> sizes, they*must not change* once the filesystem has been created
> on the device, let alone during an active mount. The whole point of
> the xfs_buftarg is to store the information the filesystem
> needs to do IO to the underlying block device so we don't have to
> chase pointers deep into the block device whenever we need to use
> static geometry information.....
>
>> + if (sbp->sb_blocksize > awu_max || awu_min > sbp->sb_blocksize ||
>> + !xfs_inode_atomicwrites(ip)) {
>> + *unit_min = 0;
>> + *unit_max = 0;
>> + return;
>> + }
> Again, this is comparing static geometry - if the block size doesn't
> allow atomic writes, then the inode flag should never be set. i.e.
> geometry is checked when configuring atomic writes, not in every
> place we need to check if atomic writes are supported. Hence this
> should simply be:
>
> if (!xfs_inode_has_atomic_writes(ip)) {
> *unit_min = 0;
> *unit_max = 0;
> return;
> } >
> before we even look at the xfs_buftarg to get the supported min/max
> values for the given device.
Thanks,
John
next prev parent reply other threads:[~2024-03-07 10:35 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-04 13:04 [PATCH v2 00/14] block atomic writes for XFS John Garry
2024-03-04 13:04 ` [PATCH v2 01/14] block: Add blk_validate_atomic_write_op_size() John Garry
2024-03-04 13:04 ` [PATCH v2 02/14] fs: xfs: Don't use low-space allocator for alignment > 1 John Garry
2024-03-04 22:15 ` Dave Chinner
2024-03-05 13:36 ` John Garry
2024-03-04 13:04 ` [PATCH v2 03/14] fs: xfs: Introduce FORCEALIGN inode flag John Garry
2024-03-04 13:04 ` [PATCH v2 04/14] fs: xfs: Make file data allocations observe the 'forcealign' flag John Garry
2024-03-05 0:44 ` Dave Chinner
2024-03-05 15:22 ` John Garry
2024-03-05 22:18 ` Dave Chinner
2024-03-06 9:41 ` John Garry
2024-03-04 13:04 ` [PATCH v2 05/14] fs: xfs: Enable file data forcealign feature John Garry
2024-03-04 13:04 ` [PATCH v2 06/14] fs: xfs: Do not free EOF blocks for forcealign John Garry
2024-03-06 21:07 ` Dave Chinner
2024-03-07 11:38 ` John Garry
2024-03-04 13:04 ` [PATCH v2 07/14] fs: iomap: Sub-extent zeroing John Garry
2024-03-06 21:14 ` Dave Chinner
2024-03-07 11:51 ` John Garry
2024-03-04 13:04 ` [PATCH v2 08/14] fs: xfs: " John Garry
2024-03-06 22:00 ` Dave Chinner
2024-03-07 12:57 ` John Garry
2024-03-04 13:04 ` [PATCH v2 09/14] fs: Add FS_XFLAG_ATOMICWRITES flag John Garry
2024-03-04 13:04 ` [PATCH v2 10/14] fs: iomap: Atomic write support John Garry
2024-03-04 13:04 ` [PATCH v2 11/14] fs: xfs: Support FS_XFLAG_ATOMICWRITES for forcealign John Garry
2024-03-06 21:43 ` Dave Chinner
2024-03-07 12:42 ` John Garry
2024-03-04 13:04 ` [PATCH v2 12/14] fs: xfs: Support atomic write for statx John Garry
2024-03-06 21:31 ` Dave Chinner
2024-03-07 10:35 ` John Garry [this message]
2024-03-04 13:04 ` [PATCH v2 13/14] fs: xfs: Validate atomic writes John Garry
2024-03-06 21:22 ` Dave Chinner
2024-03-07 10:19 ` John Garry
2024-03-04 13:04 ` [PATCH v2 14/14] fs: xfs: Support setting FMODE_CAN_ATOMIC_WRITE John Garry
2024-03-06 21:33 ` Dave Chinner
2024-03-07 11:55 ` John Garry
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