From e94f5a2285fc94202a9efb2c687481f29b64132c Mon Sep 17 00:00:00 2001
From: Jeff Moyer <jmoyer@redhat.com>
Date: Fri, 14 Aug 2015 16:15:31 -0400
Subject: [PATCH] dax: fix O_DIRECT I/O to the last block of a blockdev
commit bbab37ddc20b (block: Add support for DAX reads/writes to
block devices) caused a regression in mkfs.xfs. That utility
sets the block size of the device to the logical block size
using the BLKBSZSET ioctl, and then issues a single sector read
from the last sector of the device. This results in the dax_io
code trying to do a page-sized read from 512 bytes from the end
of the device. The result is -ERANGE being returned to userspace.
The fix is to align the block to the page size before calling
get_block.
Thanks to willy for simplifying my original patch.
Cc: <stable@vger.kernel.org>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Tested-by: Linda Knippers <linda.knippers@hp.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
fs/dax.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/dax.c b/fs/dax.c
index 93bf2f990ace..7ae6df7ea1d2 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -119,7 +119,8 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
size_t len;
if (pos == max) {
unsigned blkbits = inode->i_blkbits;
- sector_t block = pos >> blkbits;
+ long page = pos >> PAGE_SHIFT;
+ sector_t block = page << (PAGE_SHIFT - blkbits);
unsigned first = pos - (block << blkbits);
long size;