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authorKeith Busch <kbusch@kernel.org>2022-06-10 22:58:29 +0300
committerJens Axboe <axboe@kernel.dk>2022-06-27 15:29:11 +0300
commitb1a000d3b8ec582da64bb644be633e5a0beffcbf (patch)
tree960fc00a20dbe8733f847f441205dae3be20b189
parent5debd9691c3ac64c3acd6867c264ad38bbe48cdc (diff)
downloadlinux-b1a000d3b8ec582da64bb644be633e5a0beffcbf.tar.xz
block: relax direct io memory alignment
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> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220610195830.3574005-11-kbusch@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--block/bio.c9
-rw-r--r--block/fops.c4
-rw-r--r--include/linux/blkdev.h5
3 files changed, 16 insertions, 2 deletions
diff --git a/block/bio.c b/block/bio.c
index ee5fe1bb015e..933ea3210954 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1220,7 +1220,16 @@ 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 9d32df6fc315..86d3cab9bf93 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) ||
+ !bdev_iter_is_aligned(bdev, iter);
}
#define DIO_INLINE_BIO_VECS 4
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 0b8bc1fe0b2c..886c44e97434 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -424,6 +424,11 @@ struct request_queue {
unsigned long nr_requests; /* Max # of requests */
unsigned int dma_pad_mask;
+ /*
+ * Drivers that set dma_alignment to less than 511 must be prepared to
+ * handle individual bvec's that are not a multiple of a SECTOR_SIZE
+ * due to possible offsets.
+ */
unsigned int dma_alignment;
#ifdef CONFIG_BLK_INLINE_ENCRYPTION