Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit bbab37dd authored Jul 03, 2015 by Matthew Wilcox Committed by Al Viro Jul 04, 2015

block: Add support for DAX reads/writes to block devices



If a block device supports the ->direct_access methods, bypass the normal
DIO path and use DAX to go straight to memcpy() instead of allocating
a DIO and a BIO.

Includes support for the DIO_SKIP_DIO_COUNT flag in DAX, as is done in
do_blockdev_direct_IO().

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent 872eb127

fs/block_dev.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -151,6 +151,9 @@ blkdev_direct_IO(struct kiocb iocb, struct iov_iter iter, loff_t offset)
		struct file *file = iocb->ki_filp;
		struct inode *inode = file->f_mapping->host;

		if (IS_DAX(inode))
		return dax_do_io(iocb, inode, iter, offset, blkdev_get_block,
		NULL, DIO_SKIP_DIO_COUNT);
		return __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter, offset,
		blkdev_get_block, NULL, NULL,
		DIO_SKIP_DIO_COUNT);
		@@ -1173,6 +1176,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
		bdev->bd_disk = disk;
		bdev->bd_queue = disk->queue;
		bdev->bd_contains = bdev;
		bdev->bd_inode->i_flags = disk->fops->direct_access ? S_DAX : 0;
		if (!partno) {
		ret = -ENXIO;
		bdev->bd_part = disk_get_part(disk, partno);

fs/dax.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -209,6 +209,7 @@ ssize_t dax_do_io(struct kiocb iocb, struct inode inode,
		}

		/* Protects against truncate */
		if (!(flags & DIO_SKIP_DIO_COUNT))
		inode_dio_begin(inode);

		retval = dax_io(inode, iter, pos, end, get_block, &bh);
		@@ -219,6 +220,7 @@ ssize_t dax_do_io(struct kiocb iocb, struct inode inode,
		if ((retval > 0) && end_io)
		end_io(iocb, pos, retval, bh.b_private);

		if (!(flags & DIO_SKIP_DIO_COUNT))
		inode_dio_end(inode);
		out:
		return retval;