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authorMatthew Wilcox <matthew.r.wilcox@intel.com>2015-07-03 10:40:42 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2015-07-04 15:56:57 -0400
commitbbab37ddc20bae4709bca8745c128c4f46fe63c5 (patch)
tree8f0d8b16e1904ef668feb9b9df4f4041db557a20
parent872eb127e3a6cddcfca1410bb808d9b9bc773dc1 (diff)
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>
-rw-r--r--fs/block_dev.c4
-rw-r--r--fs/dax.c6
2 files changed, 8 insertions, 2 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index c7e4163ede87..5dde6dff4940 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -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);
diff --git a/fs/dax.c b/fs/dax.c
index 159f796afa85..37a0c4826c1a 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;
}

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