This is a note to let you know that I've just added the patch titled
dax: fix O_DIRECT I/O to the last block of a blockdev
to the 4.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dax-fix-o_direct-i-o-to-the-last-block-of-a-blockdev.patch
and it can be found in the queue-4.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e94f5a2285fc94202a9efb2c687481f29b64132c Mon Sep 17 00:00:00 2001
From: Jeff Moyer <jmoyer@xxxxxxxxxx>
Date: Fri, 14 Aug 2015 16:15:31 -0400
Subject: dax: fix O_DIRECT I/O to the last block of a blockdev
From: Jeff Moyer <jmoyer@xxxxxxxxxx>
commit e94f5a2285fc94202a9efb2c687481f29b64132c upstream.
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.
Signed-off-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
Tested-by: Linda Knippers <linda.knippers@xxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/dax.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -116,7 +116,8 @@ static ssize_t dax_io(struct inode *inod
unsigned 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;
Patches currently in stable-queue which might be from jmoyer@xxxxxxxxxx are
queue-4.2/blockdev-don-t-set-s_dax-for-misaligned-partitions.patch
queue-4.2/dax-fix-o_direct-i-o-to-the-last-block-of-a-blockdev.patch
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