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@xxxxxxxxx>
---
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
--
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