From: Keith Busch <kbusch@fb.com>
To: <linux-fsdevel@vger.kernel.org>, <linux-block@vger.kernel.org>,
<linux-nvme@lists.infradead.org>
Cc: <axboe@kernel.dk>, Kernel Team <Kernel-team@fb.com>, <hch@lst.de>,
<bvanassche@acm.org>, <damien.lemoal@opensource.wdc.com>,
<ebiggers@kernel.org>, <pankydev8@gmail.com>,
Keith Busch <kbusch@kernel.org>
Subject: [PATCHv5 10/11] block: relax direct io memory alignment
Date: Tue, 31 May 2022 12:11:36 -0700 [thread overview]
Message-ID: <20220531191137.2291467-11-kbusch@fb.com> (raw)
In-Reply-To: <20220531191137.2291467-1-kbusch@fb.com>
From: Keith Busch <kbusch@kernel.org>
Use the address alignment requirements from the block_device for direct
io instead of requiring addresses be aligned to the block size. User
space can discover the alignment requirements from the dma_alignment
queue attribute.
User space can specify any hardware compatible DMA offset for each
segment, but every segment length is still required to be a multiple of
the block size.
Signed-off-by: Keith Busch <kbusch@kernel.org>
---
block/bio.c | 9 +++++++++
block/fops.c | 4 ++--
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 55d2a9c4e312..44658aa57784 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1219,7 +1219,16 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2);
pages += entries_left * (PAGE_PTRS_PER_BVEC - 1);
+ /*
+ * Each segment in the iov is required to be a block size multiple.
+ * However, we may not be able to get the entire segment if it spans
+ * more pages than bi_max_vecs allows, so we have to ALIGN_DOWN the
+ * result to ensure the bio's total size is correct. The remainder of
+ * the iov data will be picked up in the next bio iteration.
+ */
size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset);
+ if (size > 0)
+ size = ALIGN_DOWN(size, bdev_logical_block_size(bio->bi_bdev));
if (unlikely(size <= 0))
return size ? size : -EFAULT;
diff --git a/block/fops.c b/block/fops.c
index 5aec9a130812..7a02b75009bb 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -45,8 +45,8 @@ static unsigned int dio_bio_write_op(struct kiocb *iocb)
static bool blkdev_dio_unaligned(struct block_device *bdev, loff_t pos,
struct iov_iter *iter)
{
- return ((pos | iov_iter_alignment(iter)) &
- (bdev_logical_block_size(bdev) - 1));
+ return pos & (bdev_logical_block_size(bdev) - 1) ||
+ !bvev_iter_is_aligned(bdev, iter);
}
#define DIO_INLINE_BIO_VECS 4
--
2.30.2
next prev parent reply other threads:[~2022-05-31 19:17 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-31 19:11 [PATCHv5 00/11] direct-io dma alignment Keith Busch
2022-05-31 19:11 ` [PATCHv5 01/11] block: fix infinite loop for invalid zone append Keith Busch
2022-06-01 8:03 ` Johannes Thumshirn
2022-05-31 19:11 ` [PATCHv5 02/11] block/bio: remove duplicate append pages code Keith Busch
2022-05-31 19:11 ` [PATCHv5 03/11] block: export dma_alignment attribute Keith Busch
2022-05-31 19:11 ` [PATCHv5 04/11] block: introduce bdev_dma_alignment helper Keith Busch
2022-05-31 19:11 ` [PATCHv5 05/11] block: add a helper function for dio alignment Keith Busch
2022-06-01 5:29 ` Christoph Hellwig
2022-06-01 8:04 ` Johannes Thumshirn
2022-05-31 19:11 ` [PATCHv5 06/11] block/merge: count bytes instead of sectors Keith Busch
2022-06-01 8:05 ` Johannes Thumshirn
2022-05-31 19:11 ` [PATCHv5 08/11] iov: introduce iov_iter_aligned Keith Busch
2022-06-01 5:30 ` Christoph Hellwig
2022-05-31 19:11 ` [PATCHv5 09/11] block: introduce bdev_iter_is_aligned helper Keith Busch
2022-05-31 21:46 ` Eric Biggers
2022-06-01 5:31 ` Christoph Hellwig
2022-05-31 19:11 ` Keith Busch [this message]
2022-06-01 5:31 ` [PATCHv5 10/11] block: relax direct io memory alignment Christoph Hellwig
2022-05-31 19:11 ` [PATCHv5 11/11] fs: add support for dma aligned direct-io Keith Busch
2022-06-01 5:32 ` Christoph Hellwig
[not found] ` <20220531191137.2291467-8-kbusch@fb.com>
2022-06-01 7:04 ` [PATCHv5 07/11] block/bounce: count bytes instead of sectors Eric Biggers
2022-06-01 7:11 ` [PATCHv5 00/11] direct-io dma alignment Eric Biggers
2022-06-01 14:28 ` Keith Busch
2022-06-01 16:12 ` Keith Busch
2022-06-06 16:24 ` Keith Busch
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