From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jeff Moyer , Linda Knippers , Dan Williams Subject: [PATCH 4.2 051/258] dax: fix O_DIRECT I/O to the last block of a blockdev Date: Sat, 17 Oct 2015 18:56:04 -0700 Message-Id: <20151018014732.636086573@linuxfoundation.org> In-Reply-To: <20151018014729.976101177@linuxfoundation.org> References: <20151018014729.976101177@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jeff Moyer 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 Tested-by: Linda Knippers Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman --- 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;