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 <[email protected]> --- fs/block_dev.c | 4 ++++ fs/dax.c | 6 ++++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 4fe10f9..0bb2993 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -152,6 +152,9 @@ 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); @@ -1170,6 +1173,7 @@ 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); diff --git a/fs/dax.c b/fs/dax.c index eaa9e06..c3e21cc 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -209,7 +209,8 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode, } /* Protects against truncate */ - inode_dio_begin(inode); + if (!(flags & DIO_SKIP_DIO_COUNT)) + inode_dio_begin(inode); retval = dax_io(inode, iter, pos, end, get_block, &bh); @@ -219,7 +220,8 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode, if ((retval > 0) && end_io) end_io(iocb, pos, retval, bh.b_private); - inode_dio_end(inode); + if (!(flags & DIO_SKIP_DIO_COUNT)) + inode_dio_end(inode); out: return retval; } -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
