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,
willy@infradead.org, axboe@kernel.dk, martin.petersen@oracle.com,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
tytso@mit.edu, jbongio@google.com, ojaswin@linux.ibm.com,
ritesh.list@gmail.com, mcgrof@kernel.org, p.raghav@samsung.com,
linux-xfs@vger.kernel.org, catherine.hoang@oracle.com
Subject: Re: [PATCH v3 15/21] fs: xfs: iomap: Sub-extent zeroing
Date: Wed, 1 May 2024 12:36:02 +0100 [thread overview]
Message-ID: <0eb8b5b6-1a59-445c-8ac1-1de2a1c0ce4a@oracle.com> (raw)
In-Reply-To: <ZjGbkAuGj0MhXAZ/@dread.disaster.area>
On 01/05/2024 02:32, Dave Chinner wrote:
> On Mon, Apr 29, 2024 at 05:47:40PM +0000, John Garry wrote:
>> Set iomap->extent_size when sub-extent zeroing is required.
>>
>> We treat a sub-extent write same as an unaligned write, so we can leverage
>> the existing sub-FSblock unaligned write support, i.e. try a shared lock
>> with IOMAP_DIO_OVERWRITE_ONLY flag, if this fails then try the exclusive
>> lock.
>>
>> In xfs_iomap_write_unwritten(), FSB calcs are now based on the extsize.
>
> If forcedalign is set, should we just reject unaligned DIOs?
Why would we? That's very restrictive. Indeed, we got to the point of
adding the sub-extent zeroing just for supporting that.
>
> .....
>> Signed-off-by: John Garry <john.g.garry@oracle.com>
>> ---
>> fs/xfs/xfs_file.c | 35 ++++++++++++++++++++++-------------
>> fs/xfs/xfs_iomap.c | 13 +++++++++++--
>> 2 files changed, 33 insertions(+), 15 deletions(-)
>>
>> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
>> index e81e01e6b22b..ee4f94cf6f4e 100644
>> --- a/fs/xfs/xfs_file.c
>> +++ b/fs/xfs/xfs_file.c
>> @@ -620,18 +620,19 @@ xfs_file_dio_write_aligned(
>> * Handle block unaligned direct I/O writes
>
> * Handle unaligned direct IO writes.
>
>> *
>> * In most cases direct I/O writes will be done holding IOLOCK_SHARED, allowing
>> - * them to be done in parallel with reads and other direct I/O writes. However,
>> - * if the I/O is not aligned to filesystem blocks, the direct I/O layer may need
>> - * to do sub-block zeroing and that requires serialisation against other direct
>> - * I/O to the same block. In this case we need to serialise the submission of
>> - * the unaligned I/O so that we don't get racing block zeroing in the dio layer.
>> - * In the case where sub-block zeroing is not required, we can do concurrent
>> - * sub-block dios to the same block successfully.
>> + * them to be done in parallel with reads and other direct I/O writes.
>> + * However if the I/O is not aligned to filesystem blocks/extent, the direct
>> + * I/O layer may need to do sub-block/extent zeroing and that requires
>> + * serialisation against other direct I/O to the same block/extent. In this
>> + * case we need to serialise the submission of the unaligned I/O so that we
>> + * don't get racing block/extent zeroing in the dio layer.
>> + * In the case where sub-block/extent zeroing is not required, we can do
>> + * concurrent sub-block/extent dios to the same block/extent successfully.
>> *
>> * Optimistically submit the I/O using the shared lock first, but use the
>> * IOMAP_DIO_OVERWRITE_ONLY flag to tell the lower layers to return -EAGAIN
>> - * if block allocation or partial block zeroing would be required. In that case
>> - * we try again with the exclusive lock.
>> + * if block/extent allocation or partial block/extent zeroing would be
>> + * required. In that case we try again with the exclusive lock.
>
> Rather than changing every "block" to "block/extent", leave the bulk
> of the comment unchanged and add another paragraph to it that says
> something like:
>
> * If forced extent alignment is turned on, then serialisation
> * constraints are extended from filesystem block alignment
> * to extent alignment boundaries. In this case, we treat any
> * non-extent-aligned DIO the same as a sub-block DIO.
ok, fine
>
>> */
>> static noinline ssize_t
>> xfs_file_dio_write_unaligned(
>> @@ -646,9 +647,9 @@ xfs_file_dio_write_unaligned(
>> ssize_t ret;
>>
>> /*
>> - * Extending writes need exclusivity because of the sub-block zeroing
>> - * that the DIO code always does for partial tail blocks beyond EOF, so
>> - * don't even bother trying the fast path in this case.
>> + * Extending writes need exclusivity because of the sub-block/extent
>> + * zeroing that the DIO code always does for partial tail blocks
>> + * beyond EOF, so don't even bother trying the fast path in this case.
>> */
>> if (iocb->ki_pos > isize || iocb->ki_pos + count >= isize) {
>> if (iocb->ki_flags & IOCB_NOWAIT)
>> @@ -714,11 +715,19 @@ xfs_file_dio_write(
>> struct xfs_inode *ip = XFS_I(file_inode(iocb->ki_filp));
>> struct xfs_buftarg *target = xfs_inode_buftarg(ip);
>> size_t count = iov_iter_count(from);
>> + struct xfs_mount *mp = ip->i_mount;
>> + unsigned int blockmask;
>>
>> /* direct I/O must be aligned to device logical sector size */
>> if ((iocb->ki_pos | count) & target->bt_logical_sectormask)
>> return -EINVAL;
>> - if ((iocb->ki_pos | count) & ip->i_mount->m_blockmask)
>> +
>> + if (xfs_inode_has_forcealign(ip) && ip->i_extsize > 1)
>> + blockmask = XFS_FSB_TO_B(mp, ip->i_extsize) - 1;
>> + else
>> + blockmask = mp->m_blockmask;
>
> alignmask = XFS_FSB_TO_B(mp, xfs_inode_alignment(ip)) - 1;
Do you mean xfs_extent_alignment() instead of xfs_inode_alignment()?
>
> Note that this would consider sub rt_extsize IO as unaligned,
> which
> may be undesirable. In that case, we should define a second helper
> such as xfs_inode_io_alignment() that doesn't take into account RT
> extent sizes because we can still do filesystem block sized
> unwritten extent conversion on those devices. The same IO-specific
> wrapper would be used for the other cases in this patch, too.
ok, fine
>
>> +
>> + if ((iocb->ki_pos | count) & blockmask)
>> return xfs_file_dio_write_unaligned(ip, iocb, from);
>> return xfs_file_dio_write_aligned(ip, iocb, from);
>> }
>> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
>> index 4087af7f3c9f..1a3692bbc84d 100644
>> --- a/fs/xfs/xfs_iomap.c
>> +++ b/fs/xfs/xfs_iomap.c
>> @@ -138,6 +138,8 @@ xfs_bmbt_to_iomap(
>>
>> iomap->validity_cookie = sequence_cookie;
>> iomap->folio_ops = &xfs_iomap_folio_ops;
>> + if (xfs_inode_has_forcealign(ip) && ip->i_extsize > 1)
>> + iomap->extent_size = XFS_FSB_TO_B(mp, ip->i_extsize);
>
> iomap->io_block_size = XFS_FSB_TO_B(mp, xfs_inode_alignment(ip));
>
>> return 0;
>> }
>>
>> @@ -570,8 +572,15 @@ xfs_iomap_write_unwritten(
>>
>> trace_xfs_unwritten_convert(ip, offset, count);
>>
>> - offset_fsb = XFS_B_TO_FSBT(mp, offset);
>> - count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
>> + if (xfs_inode_has_forcealign(ip) && ip->i_extsize > 1) {
>> + xfs_extlen_t extsize_bytes = mp->m_sb.sb_blocksize * ip->i_extsize;
>> +
>> + offset_fsb = XFS_B_TO_FSBT(mp, round_down(offset, extsize_bytes));
>> + count_fsb = XFS_B_TO_FSB(mp, round_up(offset + count, extsize_bytes));
>> + } else {
>> + offset_fsb = XFS_B_TO_FSBT(mp, offset);
>> + count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
>> + }
>
> More places we can use a xfs_inode_alignment() helper.
>
> offset_fsb = XFS_B_TO_FSBT(mp, offset);
> count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
> rounding = XFS_FSB_TO_B(mp, xfs_inode_alignment(ip));
> if (rounding > 1) {
> offset_fsb = rounddown_64(offset_fsb, rounding);
> count_fsb = roundup_64(count_fsb, rounding);
> }
ok, but again I assume you mean xfs_extent_alignment()
Thanks,
John
next prev parent reply other threads:[~2024-05-01 11:36 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-29 17:47 [PATCH v3 00/21] block atomic writes for XFS John Garry
2024-04-29 17:47 ` [PATCH v3 01/21] fs: Add generic_atomic_write_valid_size() John Garry
2024-04-29 17:47 ` [PATCH v3 02/21] xfs: only allow minlen allocations when near ENOSPC John Garry
2024-04-29 17:47 ` [PATCH v3 03/21] xfs: always tail align maxlen allocations John Garry
2024-04-29 17:47 ` [PATCH v3 04/21] xfs: simplify extent allocation alignment John Garry
2024-04-29 17:47 ` [PATCH v3 05/21] xfs: make EOF allocation simpler John Garry
2024-04-29 17:47 ` [PATCH v3 06/21] xfs: introduce forced allocation alignment John Garry
2024-04-29 17:47 ` [PATCH v3 07/21] fs: xfs: align args->minlen for " John Garry
2024-04-29 17:47 ` [PATCH v3 08/21] xfs: Introduce FORCEALIGN inode flag John Garry
2024-04-30 23:22 ` Dave Chinner
2024-05-01 10:03 ` John Garry
2024-05-02 0:50 ` Dave Chinner
2024-05-02 7:56 ` John Garry
2024-04-29 17:47 ` [PATCH v3 09/21] xfs: Do not free EOF blocks for forcealign John Garry
2024-04-30 22:54 ` Dave Chinner
2024-05-01 8:30 ` John Garry
2024-05-02 1:11 ` Dave Chinner
2024-05-02 8:55 ` John Garry
2024-04-29 17:47 ` [PATCH v3 10/21] xfs: Update xfs_is_falloc_aligned() mask " John Garry
2024-04-30 23:35 ` Dave Chinner
2024-05-01 10:48 ` John Garry
2024-05-01 23:45 ` Darrick J. Wong
2024-04-29 17:47 ` [PATCH RFC v3 11/21] xfs: Unmap blocks according to forcealign John Garry
2024-05-01 0:10 ` Dave Chinner
2024-05-01 10:54 ` John Garry
2024-04-29 17:47 ` [PATCH RFC v3 12/21] xfs: Only free full extents for forcealign John Garry
2024-05-01 0:53 ` Dave Chinner
2024-05-01 11:24 ` John Garry
2024-05-01 23:53 ` Darrick J. Wong
2024-05-02 3:12 ` Dave Chinner
2024-04-29 17:47 ` [PATCH v3 13/21] xfs: Enable file data forcealign feature John Garry
2024-04-29 17:47 ` [PATCH v3 14/21] iomap: Sub-extent zeroing John Garry
2024-05-01 1:07 ` Dave Chinner
2024-05-01 10:23 ` John Garry
2024-05-30 10:40 ` John Garry
2024-04-29 17:47 ` [PATCH v3 15/21] fs: xfs: " John Garry
2024-05-01 1:32 ` Dave Chinner
2024-05-01 11:36 ` John Garry [this message]
2024-05-02 1:26 ` Dave Chinner
2024-04-29 17:47 ` [PATCH v3 16/21] fs: Add FS_XFLAG_ATOMICWRITES flag John Garry
2024-04-29 17:47 ` [PATCH v3 17/21] iomap: Atomic write support John Garry
2024-05-01 1:47 ` Dave Chinner
2024-05-01 11:08 ` John Garry
2024-05-02 1:43 ` Dave Chinner
2024-05-02 9:12 ` John Garry
2024-04-29 17:47 ` [PATCH v3 18/21] xfs: Support FS_XFLAG_ATOMICWRITES for forcealign John Garry
2024-04-29 17:47 ` [PATCH v3 19/21] xfs: Support atomic write for statx John Garry
2024-04-29 17:47 ` [PATCH v3 20/21] xfs: Validate atomic writes John Garry
2024-04-29 17:47 ` [PATCH v3 21/21] xfs: Support setting FMODE_CAN_ATOMIC_WRITE John Garry
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