From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Moyer Subject: [PATCH 1/2] dax: fix O_DIRECT I/O to the last block of a blockdev Date: Fri, 14 Aug 2015 16:15:31 -0400 Message-ID: <1439583332-13754-2-git-send-email-jmoyer@redhat.com> References: <1439583332-13754-1-git-send-email-jmoyer@redhat.com> Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@ml01.01.org To: matthew.r.wilcox@intel.com Return-path: In-Reply-To: <1439583332-13754-1-git-send-email-jmoyer@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org 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 --- fs/dax.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/dax.c b/fs/dax.c index a7f77e1..ef35a20 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -116,7 +116,8 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, 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; -- 1.8.3.1