From: Jeff Moyer Date: Fri, 14 Aug 2015 20:15:31 +0000 (-0400) Subject: dax: fix O_DIRECT I/O to the last block of a blockdev X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=e94f5a2285fc94202a9efb2c687481f29b64132c;p=openwrt%2Fstaging%2Fblogic.git 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: Signed-off-by: Jeff Moyer Tested-by: Linda Knippers Signed-off-by: Dan Williams --- 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;