[PATCH 5/6] xfs: add DAX IO path support

Dave Chinner
2015-03-03T23:31:19Z

From: Dave Chinner <dchinner@redhat.com>

DAX does not do buffered IO (can't buffer direct access!) and hence
all read/write IO is vectored through the direct IO path. Hence we
need to add the DAX IO path callouts to the direct IO
infrastructure.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_aops.c | 35 +++++++++++++++++++++++++++--------
1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 22cb03a..28b79c5 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1558,6 +1558,30 @@ xfs_end_io_direct_write(
}
}

+static inline ssize_t
+xfs_vm_do_dio(
+ struct inode *inode,
+ int rw,
+ struct kiocb *iocb,
+ struct iov_iter *iter,
+ loff_t offset,
+ void (*endio)(struct kiocb *iocb,
+ loff_t offset,
+ ssize_t size,
+ void *private),
+ int flags)
+{
+ struct block_device *bdev;
+
+ if (IS_DAX(inode))
+ return dax_do_io(rw, iocb, inode, iter, offset,
+ xfs_get_blocks_direct, endio, 0);
+
+ bdev = xfs_find_bdev_for_inode(inode);
+ return __blockdev_direct_IO(rw, iocb, inode, bdev, iter, offset,
+ xfs_get_blocks_direct, endio, NULL, flags);
+}
+
STATIC ssize_t
xfs_vm_direct_IO(
int rw,
@@ -1566,17 +1590,12 @@ xfs_vm_direct_IO(
loff_t offset)
{
struct inode *inode = iocb->ki_filp->f_mapping->host;
- struct block_device *bdev = xfs_find_bdev_for_inode(inode);

if (rw & WRITE) {
- return __blockdev_direct_IO(rw, iocb, inode, bdev, iter,
- offset, xfs_get_blocks_direct,
- xfs_end_io_direct_write, NULL,
- DIO_ASYNC_EXTEND);
+ return xfs_vm_do_dio(inode, rw, iocb, iter, offset,
+ xfs_end_io_direct_write, DIO_ASYNC_EXTEND);
}
- return __blockdev_direct_IO(rw, iocb, inode, bdev, iter,
- offset, xfs_get_blocks_direct,
- NULL, NULL, 0);
+ return xfs_vm_do_dio(inode, rw, iocb, iter, offset, NULL, 0);
}

/*
--
2.0.0