Re: [PATCHv2 3/3] block: relax direct io memory alignment
From: Eric Biggers <ebiggers@kernel.org>
Date: 2022-05-19 00:15:01
Also in:
linux-fsdevel
On Wed, May 18, 2022 at 10:11:31AM -0700, Keith Busch wrote:
quoted hunk ↗ jump to hunk
diff --git a/block/fops.c b/block/fops.c index b9b83030e0df..d8537c29602f 100644 --- a/block/fops.c +++ b/block/fops.c@@ -54,8 +54,9 @@ static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb, struct bio bio; ssize_t ret; - if ((pos | iov_iter_alignment(iter)) & - (bdev_logical_block_size(bdev) - 1)) + if ((pos | iov_iter_count(iter)) & (bdev_logical_block_size(bdev) - 1)) + return -EINVAL; + if (iov_iter_alignment(iter) & bdev_dma_alignment(bdev)) return -EINVAL;
The block layer makes a lot of assumptions that bios can be split at any bvec boundary. With this patch, bios whose length isn't a multiple of the logical block size can be generated by splitting, which isn't valid. Also some devices aren't compatible with logical blocks spanning bdevs at all. dm-crypt errors out in this case, for example. What am I missing? - Eric