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dax: fix O_DIRECT I/O to the last block of a blockdev

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commit bbab37ddc2 (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>
This commit is contained in:
Jeff Moyer 2015-08-14 16:15:31 -04:00 committed by Dan Williams
parent 6ff33f3902
commit e94f5a2285
1 changed files with 2 additions and 1 deletions
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3
fs/dax.c
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@ -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;